FEDERAL COURT OF AUSTRALIA

SNF (Australia) Pty Limited v BASF Australia Ltd [2019] FCA 425

ORDERS

THE COURT ORDERS THAT:

1.    The appellant’s appeal be dismissed.

2.    Australian patent application no. AU 2004203785 (as amended) proceed to grant.

3.    The appellant pay the respondent’s costs of and incidental to the appeal.

4.    There be a stay on the operation of orders 2 and 3 for 21 days subject to further order.

5.    The respondent’s cross-appeal be dismissed with no order as to costs.

6.    Any previous orders made under ss 37AF and 37AG of the Federal Court of Australia Act 1976 (Cth) be varied, if necessary, so as to permit publication of the Court’s reasons.

7.    Liberty to apply.

Note:    Entry of orders is dealt with in Rule 39.32 of the Federal Court Rules 2011.

ORDERS

THE COURT ORDERS THAT:

1.    The appellant’s appeal be dismissed.

2.    Australian patent application no. AU 2013204568 (as amended) proceed to grant.

3.    The appellant pay the respondent’s costs of and incidental to the appeal.

4.    There be a stay on the operation of orders 2 and 3 for 21 days subject to further order.

5.    The respondent’s cross-appeal be dismissed with no order as to costs.

6.    Any previous orders made under ss 37AF and 37AG of the Federal Court of Australia Act 1976 (Cth) be varied, if necessary, so as to permit publication of the Court’s reasons.

7.    Liberty to apply.

Note:    Entry of orders is dealt with in Rule 39.32 of the Federal Court Rules 2011.

REASONS FOR JUDGMENT

BEACH J:

1    The appellant (SNF) has appealed two decisions of a delegate of the Commissioner of Patents made in respect of Australian patent applications no. AU 2004203785 (the 785 application) and no. AU 2013204568 (the 568 application); I will refer to both as the opposed applications. The appeals have been brought under s 60(4) of the Patents Act 1990 (Cth) (the Act), with each appeal by way of a rehearing de novo.

2    Each of the opposed applications now stands in the name of BASF Australia Limited (BASF), having previously been assigned by Ciba Specialty Chemicals Water Treatments Limited (Ciba) to BASF.

3    Each of the opposed applications seeks the grant of a standard patent for an invention(s) entitled “Treatment of aqueous suspensions”. The opposed applications are derived from an international patent application filed on 7 January 2004 no. PCT/EP2004/000042; this application was published on 22 July 2004 as international publication no. WO/2004/060819 (the PCT application). The opposed applications each claim priority from a UK patent GB 0310419.7 filed on 7 May 2003 (the priority date).

4    The decisions which are the subject of the appeals before me are:

(a)    a decision of the delegate Dr Steven Barker made on 16 February 2016 (the 785 decision); see SNF (Australia) Pty Ltd v Ciba Specialty Chemicals Water Treatments Limited [2016] APO 8; and

(b)    a decision of that delegate made on 18 October 2016 (the 568 decision); see SNF (Australia) Pty Ltd v Ciba Specialty Chemicals Water Treatments Limited [2016] APO 72.

5    The opposed applications are governed by the provisions of the Act as they stood before the “Raising the Bar” amendments (Intellectual Property Laws Amendment (Raising the Bar) Act 2012 (Cth)). Accordingly, the pre-amendment versions of provisions such as s 7 concerning novelty and inventive step continue to apply.

6    In the 785 decision, the delegate:

(a)    decided that the invention defined in each of claims (as accepted) 1 to 11, 14, 16, 17, 19, 21 to 27, 29 and 30 of the 785 application lacked an inventive step solely in light of international publication no. WO 01/92167 (the Gallagher patent) filed by Ciba and the inventors for which were inter-alia Mr Michael Gallagher and Mr Stephen Adkins, and were therefore invalid;

(b)    decided that the invention defined in each of claims (as accepted) 12, 13, 15, 18, 20 and 28 of the 785 application had not been shown to lack an inventive step and were not invalid; and

(c)    allowed the patent applicant a period of 60 days within which to propose amendments to the 785 application, indicating that the deficiency in relation to claims 1 to 11, 14, 16, 17, 19, 21 to 27, 29 and 30 could be overcome by amendment to include a co-disposal integer.

7    Pursuant to s 105(1A) of the Act and under orders made by me on 21 July 2016, the claims of the 785 application were so amended. The effect of the amendment was to limit the scope of all of the amended claims to a co-disposal process by including the requirement that the “process comprises co-disposal of coarse and fine solids as a homogenous mixture”. That amendment was sufficient to address the delegate’s concerns.

8    In the 568 decision, the delegate:

(a)    decided that the invention defined in claims 2 and 3 (as accepted) and the claims appended to claims 2 and 3 lacked an inventive step in light of the Gallagher patent;

(b)    decided that the invention defined in claim 1 (as accepted) had not been shown to lack an inventive step; and

(c)    allowed the patent applicant a period of 60 days within which to propose amendments to the 568 application to overcome the deficiency in relation to claims 2 and 3 concerning the Gallagher patent.

9    Again, pursuant to s 105(1A) of the Act and under the orders made by me on 21 December 2016, the claims of the 568 application were amended. The effect of the amendment was to limit the scope of all of the amended claims to a co-disposal process by making a similar amendment as for the 785 application.

10    As noted, the opposed applications are derived from the PCT application filed on 7 January 2004. Ciba had previously also divided out five innovation patents from the PCT application, which were the subject of proceedings before Kenny J discussed below. It had also divided out various standard patent applications from the PCT application. Two of those applications are the opposed applications which are the subject of the present appeals. Another application (AU 2012216282) has been the subject of an opposition proceeding in which a decision was handed down by the delegate on 18 April 2018. SNF has filed a notice of appeal in respect of that decision which appeal I am also presently case managing. There have also been other applications for standard patents derived from the PCT application that have been withdrawn, lapsed or refused; there is yet a further application awaiting examination. For present purposes I need say nothing more about them.

11    As I have said, the parties were involved in Federal Court proceedings which concerned, inter-alia, the validity of five innovation patents which were filed as divisional applications of the 785 application.

12    In 2008, SNF commenced revocation proceedings in Federal Court proceedings number VID 447 of 2008 (the 2008 proceedings) concerning the validity of innovation patents nos. 2006100744, 2006100944, 2007100377, 2007100834 and 2008100396 (the innovation patents). Ciba cross-claimed for infringement.

13    The innovation patents were held to be valid by Kenny J and Ciba succeeded in its cross-claim for infringement (SNF (Australia) Pty Ltd v Ciba Speciality Chemicals Water Treatments Ltd (2011) 92 IPR 46).

14    SNF appealed that decision to the Full Federal Court, where a majority dismissed the appeal (SNF (Australia) Pty Ltd v Ciba Speciality Chemicals Water Treatments Ltd (2012) 204 FCR 325). SNF then sought special leave to appeal, which leave was refused.

15    Subsequently, in April 2014 SNF filed an interlocutory application seeking to re-open the 2008 proceedings and her Honour’s judgment therein. That application was dismissed (SNF (Australia) Pty Ltd v Ciba Specialty Chemicals Water Treatments Limited (2015) 114 IPR 231). SNF then sought leave to appeal that decision, but the Full Federal Court refused such leave (SNF (Australia) Pty Ltd v Ciba Speciality Chemicals Water Treatments Ltd [2016] FCAFC 88).

16    Further, in November 2011 a related entity of SNF, SNF Inc., commenced proceedings against Ciba in the Canadian Federal Court seeking a declaration that a patent related to the opposed applications (the Canadian patent), which claimed essentially the same process as the opposed applications, was invalid. The Canadian patent was also derived from the PCT application. On 24 August 2015, Phelan J determined that the Canadian patent was invalid (SNF Inc. v Ciba Specialty Chemicals Water Treatments Limited (2015) 133 CPR (4th) 259; [2015] FC 997).

17    I would note at this point that many of the witnesses who gave evidence before me on these appeals have previously given evidence in these other proceedings. Moreover, some aspects of Kenny J’s reasoning discusses issues that I am also concerned with. Nevertheless, I must deal with the issues on the evidence before me. Further, some of Kenny J’s analysis must be understood in light of the fact that she was dealing with innovation patents whereas I am concerned with applications for standard patents.

18    In general, SNF contends before me that:

(a)    the invention so far as claimed in any claim of the opposed applications does not involve an inventive step;

(b)    the invention so far as claimed in any claim of the opposed applications was secretly used in the patent area before the priority date of that claim by or on behalf of or with the authority of the patent applicant or nominated person or the patent applicant’s or nominated person’s predecessor in title to the invention; and

(c)    all of the claims of the opposed applications are not novel except for:

(i)    claims 5, 18, 21 and 23 for the 785 application; and

(ii)    claims 15, 27 and 30 of the 568 application.

19    BASF has cross-appealed those parts of the 785 decision and 568 decision in which the delegate held that certain claims of the 785 application being claims 1 to 11, 14, 16, 17, 19, 21 to 27, 29 and 30 and certain claims of the 568 application being claims 2 and 3 and the appended claims lacked an inventive step in light of the Gallagher patent. That was the only ground upon which the delegate held any claims of the opposed applications to be invalid. But notwithstanding its cross-appeal, BASF has amended the claims of the 785 application and the 568 application to overcome the findings of the delegate by narrowing the relevant claims of the opposed applications to include a “co-disposal” integer. In the 785 decision the delegate concluded that “it has not been shown that the claims relating to co-disposal lack inventive step” (at [325]). In the 568 decision the delegate held that claim 1 of the 568 application features the “significant new step” of co-disposal (at [21]), held that the Gallagher patent suggested “a preference for disposal of tailings that are substantially composed of fine particles” (at [39]), and said that “I am satisfied that the evidence shows that it was known to combine fine and coarse particles. However, the evidence does not show that it would have been a matter of routine to do this in the context of the problem” (at [56]). Given the amendments ordered by me and my decision on SNF’s appeals, it is not necessary to say anything further on BASF’s cross appeals.

20    BASF also contends by its notices of contention that the delegate erred in finding that the person skilled in the art could as at the priority date have been reasonably expected to have ascertained the relevant prior art relied on by SNF. I will deal with this later when I discuss the s 7(3) question.

21    Now SNF bears the onus in relation to establishing each ground of opposition and corresponding ground of appeal before me. The authorities establish that for the opposition to be upheld it must be clear that the patent, if granted, would not be valid (Meat & Livestock Australia Limited v Cargill, Inc (2018) 354 ALR 95; (2018) 129 IPR 278; [2018] FCA 51 at [11] (MLA (No 1))).

22    Further, in MLA (No 1) at [11], I agreed with the views expressed by Bennett J in Austal Ships Pty Ltd v Stena Rederi Aktiebolag (2005) 66 IPR 420 (Austal Ships), that where there are conflicting sets of expert opinions on a principal question such as lack of inventive step, unless one set of views can be rejected on proper grounds, the opponent will not have discharged its legal burden to the requisite degree. But the higher standard of satisfaction does not apply to findings of underlying primary facts. As Bennett J explained in Austal Ships at [12]:

I can accept that a lower standard may apply to proof of evidence such as whether a document has been published or, indeed, whether a prior art vessel was well-known. I do not accept that it properly applies to the factual question that itself is the test for obviousness or lack of inventive step. Where the factual question is itself the legal test, as set out in s 7(3) of the Act, it seems to me that it should be determined at the higher standard. That means that where there are two opposing expert views that are conclusive on obviousness, both presented bona fide by witnesses of accepted expertise, unless one set of views can be rejected on proper grounds, the legal burden to establish a ground of opposition is not discharged; the court cannot be practically certain that obviousness or lack of inventive step is established.

23    Further, in Aspirating IP Ltd v Vision Systems Ltd (2010) 88 IPR 52, Besanko J cited the above passage in Austal Ships and said at [35] that:

The primary facts are to be established on the balance of probabilities, but the ultimate facts – the facts leading directly to a conclusion of a lack of novelty or a conclusion of obviousness – must be proved to the level of practical certainty.

24    Now there has been limited judicial consideration of particular matters which must be proved to a level of being “clear” as opposed to those that can be established on the balance of probabilities. But decisions of various delegates of the Commissioner of Patents provide some guidance on where the division between the two standards has been drawn in practice.

25    For example, delegates have found that the lower standard of proof is applicable as to whether a matter formed part of the common general knowledge, whether a document has been published and whether in the context of secret use an invalidating sale occurred before the priority date. Contrastingly, delegates have found that the higher standard of proof is applicable as to whether a person skilled in the art would achieve the same results as the invention so far as claimed using slightly different techniques and altered conditions, whether the claims of the invention so far as claimed lack utility and whether the claims of the invention lack novelty.

26    In my view, the following matters are required to be established by SNF at the lower standard of on the balance of probabilities:

(a)    the materials routinely referred to by a person skilled in the art;

(b)    whether various matters formed part of the common general knowledge at the priority date and what about them and their use was common general knowledge at the priority date including, in the present context, the use of co-disposal processes, the use of belt presses and centrifuges, the use of processes involving the addition of flocculant to thickener underflow in the outlet pipe from the thickener (secondary dosing), the use of flocculants in treating tailings, and the variables routinely adjusted in their use, whether a treatment process which worked effectively on one mineral type would also work effectively on other mineral types, and the use of processes involving the deposition of thickener underflow onto a slope, wall or floor in order to allow tailings to become beached and water to flow out to a lower point for re-use (tailings beaching); I note that it is not now asserted that the use of secondary dosing in tailings beaching (SDITB) was part of common general knowledge at the priority date;

(c)    whether relevant prior art being the Backer & Busch papers, the Condolios patent, the Gallagher patent and the Pearson patent (I will precisely identify these later) would have been ascertained, understood and regarded as relevant by a person skilled in the art at the priority date, although there is an argument for saying that the higher standard should apply;

(d)    what is disclosed in the Backer & Busch papers, the Condolios patent, the Gallagher patent and the Pearson patent, although there is an argument for saying that the higher standard should apply;

(e)    what use was made of the claimed invention by Ciba at Yarraman, Sandalwood and Ardlethan (I will identify these locations later) before the priority date and what was the nature of that use; and

(f)    whether the Cable Sands documents (I will describe these later) would have been treated by a person skilled in the art as a single source of information, although there is an argument for saying that the higher standard should apply.

27    On questions of construction, I am also prepared to apply and have applied the lower standard albeit that there is some force in BASF’s submissions that the higher standard should apply.

28    But in my view the following matters are required to be established to the higher standard:

(a)    whether any of the claims of the opposed applications were obvious in light of common general knowledge alone;

(b)    whether any of the claims of the opposed applications were obvious in light of common general knowledge combined with any of the prior art relied on by SNF;

(c)    whether the claimed invention was secretly used by Ciba prior to the priority date; and

(d)    whether any of the claims of the opposed applications lacked novelty in light of the disclosures in the Cable Sands documents.

29    In summary and for the reasons that follow, I have determined to dismiss each of SNF’s appeals.

30    For convenience, I have divided my reasons into the following sections:

(a)    Technical background ([32] to [141]);

(b)    The opposed applications ([142] to [220]);

(c)    The witnesses ([221] to [261]);

(d)    The person skilled in the art ([262] to [279]);

(e)    Construction of the claims ([280] to [372]);

(f)    Common general knowledge ([373] to [501]);

(g)    Obviousness – legal principles ([502] to [536]);

(h)    Obviousness in light of common general knowledge alone ([537] to [1080]);

(i)    Common general knowledge plus s 7(3) documents ([1081] to [1410]);

(j)    Secret use ([1411] to [1720]);

(k)    Lack of novelty ([1721] to [1782]); and

(l)    Conclusion ([1783] to [1784]).

31    In these reasons, in terms of the respondent to the appeals I will generally refer to BASF, save for when I need to refer to Ciba directly in discussing contemporaneous conduct and dealings before the priority date.

TECHNICAL BACKGROUND

32    For the most part, the following matters that I have described in this section were common general knowledge as at the priority date and do not appear to be in dispute. It is useful to set these out in order to appreciate the later discussion of the relevant technical issues. In part, I have drawn upon the helpful discussion of some of these matters given by Dr Ross de Kretser, an expert witness called by SNF. Before getting into the detail, let me set out a mini glossary.

33    Terms or expressions used in the relevant field include the following:

(a)    “beach angle” refers to the slope or angle of a deposit (relative to underlying material) which forms a stack or heaped geometry;

(b)    “beneficiation” is a process of concentrating the value(s) in an ore by separation from waste material;

(c)    “bimodal distribution of particle sizes” means there are two distinct sizes of particles within the solid material. Often these are referred to as “fines” and “coarse” fractions;

(d)    “co-disposal” means, in simple terms, the disposal of a combination of both coarse and fine tailings particles. In some cases this will involve a clearly bi-modal size distribution which has both coarse and fine particles;

(e)    “flocculants” are high molecular weight polymers that induce aggregation of solid particles. This occurs by individual flocculant molecules co-adsorbing on two or more solid particles and binding them together. Due to the increase in their size, the bound solids (often called “aggregates”, “floccules” or “flocs”) have a faster settling rate, but a much lower density, than the individual solids particles;

(f)    “intrinsic viscosity” is a measure of the capability of a polymer in solution to enhance the viscosity of the solution. It is related to the volume per unit mass occupied by flocculant molecules in solution and is measured in the unit “dL/g”, which is decilitres per gram;

(g)    “rheology” is the study of deformation and flow of fluid matter;

(h)    “spirals” are equipment used in mineral processing industry to beneficiate an ore by means of the forces imposed on particles as they flow under gravity in a spiralling motion;

(i)    a “stack” or a “heaped geometry” is a deposit of material which is characterised by being larger at the bottom than at the top;

(j)    “tailings” are the end product of a mineral processing operation. Tailings are what remain of an ore after the value(s) (e.g. alumina, coal, copper, diamond, gold, nickel, uranium, zinc) have been extracted during the processing operation; and

(k)    “yield stress” means, in simple terms, a measure of the minimum force required to be applied to an object to make it deform (i.e. begin to behave as a fluid).

34    Mineral processing is the processing of mined materials to separate the valuable component of the ore such as alumina, coal, copper, diamond, gold, nickel, uranium, zinc from the waste material i.e. the tailings. Such processing usually produces tailings that have the following characteristics:

(a)    First, they are in slurry form, comprising process water and particulate matter.

(b)    Second, the particulate matter is comprised of large amounts of quartz/silica, various types of clays, and other minerals depending on the host rock for the ore.

(c)    Third, the particle size of the particulate matter depends on the level of grinding required for mineral extraction which in many cases is related to the type of mineral and nature of the deposit.

(d)    Fourth, in many operations, multiple tailings streams are generated with different characteristic particle size distributions. For example, in mineral sands processing, slimes (fine) and sand (coarse) streams are generated from different parts of the processing circuit. Sand streams are also generated in alumina refining in addition to the fine red mud tailings. In coal processing a coarse reject stream is commonly generated in addition to the fine tailings.

35    Tailings slurries vary in their consistency from having a low solids concentration, and accordingly, being very liquid, to having a higher solids concentration and being more viscous. The solids in the tailings may consist of fine particles, coarse particles or a mixture of both. The fine particles are often referred to as “clay” or “fines”, and the coarse particles are often referred to as “sand”.

36    The particle size of the particulate matter strongly depends on the level of grinding required for mineral extraction which in many cases is related to the type of mineral and nature of the deposit. For example, typical tailings particle sizes can be as follows:

(a)    lead zinc: top size 80 to 500 microns, 80% passing 30 to 150 microns;

(b)    gold-silver-platinum: top size 80 to 500 microns, 80% passing 30 to 150 microns;

(c)    coal: top size 100 to 1500 microns; 80% passing 10 to 900 microns;

(d)    bauxite (red mud): top size 100 microns, 80% passing 5 to 10 microns;

(e)    mineral sands – slimes: top size 75 microns, 80% passing 10 to 50 microns; and

(f)    mineral sands – sand: top size 1000 microns.

37    Mineral tailings typically have a range of particle sizes, generally within the range of 0.5-400 microns, depending on the ore mineralogy and processing regime.

38    Coal, mineral sands, copper, gold, lead, zinc, red mud, silver, uranium and platinum tailings often comprise a mixture of coarse and fine particles. Phosphate and uranium tailings usually only comprise fine particles.

39    Tailings with a bimodal distribution of particle sizes were common at the priority date. The bimodal size distribution of tailings could arise due to either the nature of the treatment process and the mineral being mined, or by deliberate addition of coarser material to a finer tailings stream. Tailings with a bimodal distribution of coarse and fine particle sizes is typical in the mineral sands industry. In contrast, in other industries such as coal tailings, the size distribution is more gradual across a scale of sizes between coarse and fine particles.

40    Let me now address the question of thickeners. A thickener is essentially a large tank which is continuously fed with tailings slurry, typically through a central feeding arrangement called a feedwell, and which has sufficient volume to allow solid particles to settle to the bottom of the thickener and produce a clear overflow of suspending fluid. That overflow is typically recycled to the plant for re-use, or in some cases may contain the valuable product which is processed elsewhere in the plant.

41    The settled tailings or what is referred to as “thickener underflow” are then pumped at relatively low solids concentrations to the deposition area in pipelines or less commonly in open launders or channels.

42    A schematic of a thickener, illustrating key features is set out below:

43    As at the priority date, two of the types of thickeners being used were conventional thickeners and paste thickeners. Conventional and paste thickeners are similar pieces of equipment that are designed and operated to produce underflows of different consistencies. The aim of paste thickeners is to increase water recovery and produce a denser underflow compared to conventional thickeners. Paste thickeners are typically used in relation to alumina tailings which contain caustic soda. However, the underflow from both thickeners is generally transported to a deposition area via a tailings pipeline or launder.

44    Thickener underflow is typically disposed of by pumping the underflow through a conduit to a disposal area where the material is allowed to stand, with a view to land reclamation and water recycling. Typically thickener underflow has a solids concentration of between 15% to 80% by weight, being the percentage of solids in the tailings, the rest being water.

45    Let me now turn to discuss flocculants. Water soluble flocculants are used to increase the yield stress of tailings thereby thickening the tailings in order to improve the dewatering and disposal of tailings, irrespective of the mineral type.

46    Flocculants cause tailings to aggregate into flocs which on deposition under certain conditions start to stick together to form a structure that is permeable and allows for further dewatering. With dewatering, the yield stress of the material increases. The addition of the flocculants co-immobilizes the coarse and fine particles in the tailings on deposition. Typically, the higher the flocculant dose, the greater the flocculation of the tailings.

47    Commercially available flocculants including polyacrylamide which are commonly used in the treatment of tailings are either positively charged (cationic), negatively charged (anionic) or uncharged (non-ionic). The choice of charge of the flocculant is governed by the qualities of the tailings to be treated.

48    Flocculant manufacturers make flocculants with different molecular weights which react differently depending on the characteristics of the tailings. The higher the molecular weight, the longer the flocculant chain. The molecular weight of a flocculant is related to its intrinsic viscosity. The higher the molecular weight of the flocculant, the higher its intrinsic viscosity. Almost all commercially available flocculants have an intrinsic viscosity of greater than 5dl/G.

49    Flocculants with a high molecular weight are more effective for “bridging” or “connecting” the particles in the tailings as part of the flocculation process. Flocculants with a higher molecular weight have longer and more cross-linked arms which make them more effective at connecting with more particles in the tailings.

50    Flocculants formed from ethylenically unsaturated water-soluble monomer or a blend of monomers were well known as at the priority date.

51    Commercially available flocculants as at the priority date could be formed from:

(a)    monomer(s) selected from the group consisting of (meth)acrylic acid, allyl sulphonic acid and 2-acrylamido-2-methyl propane sulphonic acid as the free acids or salts thereof, optionally in combination with non-ionic co-monomers, selected from the group consisting of (meth)acrylamide, hydroxy alkyl esters of (meth)acrylic acid and N-vinyl pyrrolidone;

(b)    monomer(s) selected from the group consisting of (meth) acrylamide, hydroxy alkyl esters of (meth) acrylic acid and N-vinyl pyrrolidone; and

(c)    monomer(s) selected from the group consisting of dimethyl amino ethyl (meth) acrylate methyl chloride, (DMAEA.MeCI) quat, diallyl dimethyl ammonium chloride (DADMAC), trimethyl amino propyl (meth) acrylamide chloride (ATPAC) optionally in combination with non-ionic co-monomers, selected from the group consisting of (meth) acrylamide, hydroxy alkyl esters of (meth) acrylic acid and N-vinyl pyrrolidone.

52    Dr de Kretser gave evidence that flocculants added to tailings in aqueous solution achieve the peak level of flocculation within 10 to 20 seconds after addition to tailings, or in even shorter time periods. After 1.5 minutes after addition, depending on the level of agitation, the level of flocculation (yield stress) would be significantly lower than that peak level. Other evidence was to the effect that an aqueous solution will typically take a few seconds to mix and flocculate the slurry.

53    As I have said, a flocculant (or polymer) is a substance, most commonly synthetic, which is added to slurries to produce flocculation. Flocculation is the aggregation of suspended particles into larger clumps called floccs which are then able to more readily separate from the suspension or slurry. Let me at this point distinguish between a coagulant and a flocculant.

54    Coagulation facilitates the destabilisation and then elimination of colloidal particles, which are insoluble particles suspended in water. In other words, it facilitates the aggregation of insoluble particles suspended in a solution, where they would otherwise be evenly distributed. Coagulants do so by neutralising or “screening” the like charges of suspended particles, preventing repulsion between the particles, and facilitating either attractive forces (for example van der Waals forces) or bonding between the particles. Coagulation can form bonded flocs of particles, however, these flocs are less dense and less extensive than flocs created by flocculation.

55    Flocculation tends to be used where colloidal particles are already destabilised (i.e. the particles are not evenly dispersed in a solution, whether by coagulation or otherwise). Flocculants assemble the destabilised colloidal particles into aggregates. Flocculants, being long polymer chains, fix the destabilised particles and aggregates along the polymer chain, generally via ionic or hydrogen bonding. Properties of the flocculant used will depend on the nature of the solution. Anionic (negatively charged) flocculants “donate” negative charges to the suspended particles and cationic (positively charged) flocculants “donate” positive charges to the suspended particles.

56    The following discussion with Dr de Krester is also relevant:

MR SHAVIN: His Honour asked a question of me when we were opening the case as to the difference between a coagulant and a flocculant. Could you perhaps explain to his Honour what the difference is?---Typically a coagulant is a reagent which is – has the purpose of creating small flocs. So it would – I mean, probably the best thing is to consider it in contrast to a flocculant, which is a large, long chain polymer, which has the objective of grabbing particles and pulling them together into a more open floc. A coagulant is typically creates flocs, but they’re denser, less extensive. So there’s – so coagulation versus flocculation is typically characterised by the extent and size of the particle or the floc that you form, but also the types of reagents differ in the ones that are used to coagulate versus flocculate. So coagulation could be via changing the charge between particles, so they just – so simply the particles attract each other.

HIS HONOUR: So if you’ve got particles that have the same charge and would otherwise repel if you added a mineral salt or something - - -?---That’s – that’s correct.

- - - you would neutralise the charge, which will allow them to aggregate and create the small flocs?---Yes. And so some cases coagulation can be induced just by the concentration of sale in a suspending fluid.

Yes?---And what that actually does – you can still have like charge particles, but the repulsion between them is screened out because you have a lot of other ions.

Yes?---And they get sufficiently close that there’s – I’m not sure if you’re familiar with Van der Waals forces.

Yes, I am. Yes?---So that attractive force can actually – they can approach close enough that they – they reach what – what’s called an attractive minimum. So that’s one method of coagulation. There are also more, I guess, physical coagulants, in the sense that a reagent is added which precipitates and actually sticks, essentially, particles together. And there’s also the case of organic coagulants, which are polymers, but they’re smaller, shorter chain polymers, so they typically act maybe of around 100,000 molecular weight, compared to bridging polymers, which might be upwards of a million molecular weight.

So for a coagulant in some cases it can bond with the particles, but with all flocculants there is that bonding with the interaction of the polymer?---Yes. Yes. With flocculants there’s typically a physical absorption component to it.

Yes?---Coagulants can - - -

May be?---Can be electrostatic or physical.

Yes?---And typically coagulants – or coagulants are commonly used in conjunction with flocculants, but they can also be used in isolation as well.

57    Let me return to flocculants and elaborate further. As I have said, flocculants are composed of long chains of monomers that have been chemically bonded. When activated, flocculants have an elongated chain-like structure containing sites which can bind to solid particles when added to a suspension of particles in fluid. When a flocculant in aqueous solution mixes with a suspension, the flocculant chains adsorb or bind to the particles, aggregating them into flocs. Due to their increase in effective size, the flocs settle faster under gravity than the primary particles alone, increasing dewatering rates.

58    Flocculants have a wide range of chemistries and characteristics and the choice of the particular chemistry and characteristic of the flocculant is made on the basis of achieving the desired aggregation of particles in the system in question.

59    Conventional flocculants available before the priority date were typically a combination of polyacrylamide and polyacrylate monomers in a range of molecular weights. As I have said, molecular weight is determined by the length of the flocculant chain and affects the solids capture ability of the flocculant. Longer flocculant chains (having a higher molecular weight) have more active sites with which to trap solid particles. Higher molecular weight flocculants were also more viscous. Polyacrylamide was a well known form of flocculant that had a high molecular weight.

60    Further, as I have said, flocculants can be anionic, cationic or non-ionic, but the majority of flocculants used in mineral processes before the priority date were either anionic or non-ionic.

61    Flocculant was most commonly delivered to site in dry powder or emulsion form due to the lower transport cost and its more stable storage characteristics. Flocculants were rarely delivered to site in liquid (aqueous) form.

62    Irrespective of the physical form in which a flocculant was delivered, its use in practice in many cases required the flocculant to be converted into aqueous solution.

63    In dry powder and (to a lesser extent) emulsion form, the chains in a flocculant will be tightly coiled. In order for a flocculant to perform effectively, the flocculant chains must be dissolved in water and fully uncoiled so as to maximise the available binding sites. The preconditioning to achieve this state depended on the physical form of the flocculant. In particular the following may be observed:

(a)    Powder flocculant was added, sometimes with a wetting agent, to process water in a mixing device before storage in conditioning tanks to allow time for the powder to dissolve and for the flocculant chains to uncoil.

(b)    Emulsion flocculant was supplied as a water-in-oil emulsion i.e. droplets of concentrated flocculant solution in an oil carrier. Prior to use, the emulsion was inverted in a mixing device to release the concentrated flocculant solution into process water. The inverted flocculant solution was then transferred to conditioning tanks, again to allow time for the flocculant chains to uncoil.

(c)    Liquid (aqueous) flocculant could be supplied in a fully dissolved state such that it could be used directly from the source tanks on delivery. This avoided the need for a flocculant preparation plant, but increased transport cost per unit weight of flocculant, effectively limiting its economic viability to low tonnage / low dosage operations. The supplied flocculant could be more concentrated than required by the application to reduce transport costs, and could be diluted before addition as required.

64    In most cases, the activated flocculant was then added to the tailings from the conditioning tanks with a level of dilution dictated by the application. Typically, for thickening applications, this dilution was by a factor of 10.

65    Further, different forms of water soluble flocculant required different activation times in water. In particular, dry powder flocculant required the longest activation time, flocculant in an emulsion required a shorter activation time and flocculant added in aqueous solution required no activation time at all.

66    If flocculant was added to tailings in a fully activated solution, it would begin flocculating within a few seconds.

67    As I say, when the flocculant was supplied in dry powder form it was mixed and aged in a mixing tank prior to addition to the thickener or thickener underflow to allow the flocculant to unravel and convert to an aqueous solution.

68    And as I say, when the flocculant was supplied in emulsified form, the normal practice would be to invert or “flip” the emulsion and turn it into an aqueous solution prior to addition to the thickener or thickener underflow.

69    The expertise and equipment necessary to convert flocculant from either dry powder or emulsified form to aqueous solution were present at most mine sites. Flocculant was commonly added in aqueous solution to thickeners, belt presses, and centrifuges. After preparation of the flocculant into aqueous form, the prepared flocculant was generally diluted prior to addition to thickeners, belt presses, and centrifuges. Dilution was required to reduce flocculant viscosity and enhance dispersion or mixing of the flocculant solution into the tailings. This facilitated efficient flocculant-particle interaction.

70    Let me now say something about dose point. A key factor to consider in the operation of thickeners, belt press filters and centrifuges is the location at which the flocculant was added. It was important to take the dose point into account to enhance the performance of the equipment and therefore to improve the characteristics of the tailings when discharged in the deposition area.

71    It was necessary to determine the appropriate point at which there was sufficient time after the flocculant was added for it to fully mix and react with the tailings, but not so much time as to allow shear forces to break down the flocs that were formed prior to the point where the material reaches deposition.

72    As to dosage, the following may be noted. The dose used to treat a mineral suspension in a thickener would have a significant influence on the strength of the tailings material in that it would have a higher yield strength.

73    Generally speaking, provided there was adequate mixing, the greater the dose of flocculant the greater the flocculation.

74    The size of flocs formed after flocculant addition was affected by the dosage. It was known that if larger flocs were desired, with a concomitant increase in dewatering rate, a larger dosage of flocculant would typically be required.

75    The addition of flocculants to tailings slurries can significantly change their rheology and dewatering properties. This can result in a slurry that has a higher viscosity, higher yield stress, higher compressive strength and increased permeability due to an increase in the effective particle size caused by the aggregation of fine particles in the slurry. The resultant change in rheology and dewaterability was a function of the dose of the flocculant. Larger doses of flocculant could result in a larger improvement in permeability, but with a stiffer particle network (i.e. increased yield stress at a fixed solids concentration).

76    The appropriate flocculant dosage for a particular application varied significantly based on the following factors which were idiosyncratic to each mine site:

(a)    desired performance e.g. settling rate, settled density, shear sensitivity / robustness;

(b)    flocculant type and process water chemistry;

(c)    combination with other conditioning reagents e.g. inorganic coagulants, dewatering aids;

(d)    solids particle size distribution;

(e)    solids particle composition / mineralogy;

(f)    solids concentration at point of addition;

(g)    shear conditions at and after point of addition; and

(h)    number of different points of floc addition.

77    At this point it is useful to say something about a number of fundamental material properties which govern the flow and dewatering of tailings irrespective of the method of treatment or transport of the tailings, again drawing from some of the evidence given by Dr de Krester.

78    Let me begin with rheology. The rheology of the slurry refers to its viscosity and flow characteristics.

79    The viscosity is a measure of the consistency of a slurry which governs the amount of energy required to make the slurry flow from one point to another. A low viscosity material such as water will flow readily whereas a more viscous material such as mud (or honey) requires more energy to make it flow.

80    In the case of suspensions of particles in liquid, in addition to having elevated viscosities, the slurries can exhibit a yield stress. Yield stress describes a stress level which must be exceeded before flow can be initiated. For example, toothpaste will not flow unless a sufficient force is applied to it - that amount of force is the yield stress of the toothpaste. Yield stress is measured in pascals (Pa) (i.e. force, in newtons, per square metre). The presence of a yield stress is an indication that an interconnected network exists between the particles within a material. This interconnection could be via attractive forces sticking particles together in the slurry, or simply due to the interlocking of particles as the solids concentration increases to the point where they can no longer move freely relative to one another.

81    Let me now turn to dewatering. The primary physical properties that govern the dewatering of any slurry are its permeability and its compressive behaviour.

82    The permeability of a slurry is governed by the friction generated when solid and liquid particles move relative to each other within the slurry. At low solids concentration (i.e. settling), the solid particles can be considered as moving within a liquid continuum. At high solids concentrations, the liquid can be considered as moving within a solid continuum, such as would be the case in filtration or consolidation within a tailings storage facility (TSF). Therefore, permeability governs the rate at which liquid can be expressed or separated from the solid particles in a dewatering operation.

83    A schematic illustrating the range of solids concentrations and inter-particle structures over which the concept of permeability relates to is set out below:

84    The top section of this diagram shows flocculant acting on colloidal particles to form a floc, and ultimately a network of flocs within the material. Once the network has been formed, the application of a stress (for example by the weight of overburden generated by the addition of further material above) compresses the network causing the release of fluid (i.e. further dewatering of the deposited material). Permeability affects the rate of dewatering of the material across the entire spectrum of states depicted.

85    In simple terms, a highly permeable slurry will release water faster than a less permeable slurry; this is the case in thickeners, filters or on TSF deposition.

86    Let me elaborate on compressive behaviour. As the solids concentration of a slurry is increased, a point is reached where the solid particles within the slurry become interconnected. At this point, a solid particle network exists which has an integral strength which can withstand application of an external force (the yield stress). This condition could be generated either through dewatering of a slurry (e.g. sedimentation) or through the modification of inter-particle forces and structure within the slurry, or the addition of more solid particles to the slurry.

87    The compressive behaviour of a slurry refers to the ability of this network of particles to rearrange under the influence of an external force, thereby expressing liquid from between the particles. To facilitate compressive yielding of this network of particles at a particular solids concentration, an external force must be applied that exceeds the integral strength of the network (this is sometimes termed the “compressive yield stress”). At this point, the network will compress to a higher solids concentration with a higher integral strength. Ultimately, the compressive behaviour of a solid-liquid mixture governs the ultimate amount of liquid which can be expressed or removed from the mixture in a dewatering operation.

88    The diagram below illustrates the typical trend in network strength (compressive yield stress or shear yield stress) with increasing solids concentration. This shows that as the solids concentration increases, a point is reached where the strength of the material rapidly increases due to the interaction between the particles within the mixture.

89    There are various factors which significantly affect the rheology and dewatering characteristics of tailings slurry, both within dewatering equipment in a mineral processing plant (i.e. thickeners, filters, centrifuges) as well as within the TSF (i.e. water release upon deposition and long term consolidation after placement).

90    First, a higher solids concentration will usually result in a slurry with a higher viscosity, higher yield stress and a higher compressive strength. This is related to an increase in the number of collisions or interactions between particles under flow or in dewatering.

91    In terms of permeability, a higher solids concentration will result in a lower permeability. This is because the more solid particles in the slurry, the less available space for liquid to flow between those particles.

92    Viscosity, yield stress, compressive strength and permeability are all strong functions of slurry solids concentration.

93    Second, for the same material, a finer particle size distribution will generally have a higher viscosity, higher yield stress, higher compressive strength but lower permeability than a coarser particle size distribution. The lower permeability is due to the more tortuous flow path between or by the particles in the finer suspension. However, the finer particles increase the strength of the network (more particle interactions per unit volume) which in turn produces a higher yield stress.

94    In addition, the relative amounts of coarser and finer material within a size distribution can affect the packing of the particles in the slurry, and therefore affect the viscosity, yield stress, compressive strength and permeability of the slurry.

95    Third, the composition of dissolved ions within the process water influences the interaction between fine particles in the slurry and can result in attractive or repulsive forces between them. This can result in a slurry with a higher viscosity, yield stress and compressive strength due to a stronger inter-particle network (attractive forces). Conversely, a slurry with lower viscosity, no yield stress or compressive strength can be generated with repulsive forces between the particles. In terms of permeability, attractive forces typically promote fine particle aggregation, with a resultant increase in permeability at a given solids concentration.

96    Fourth, the type of minerals present within the tailings particles can have a strong influence on slurry rheology and dewatering. In particular, clay minerals were well known sources of increased viscosity in tailings slurries due to their plate-like structure and high surface area to particle volume ratio. Shear yield stress varies for a range of mineral tailings slurries with varying mineralogy, water chemistry, particle size and shape.

97    Fifth, the addition of chemical modifiers to tailings slurries can significantly change their rheology and dewatering properties, largely based on whether they promote attraction or repulsion between the particles.

98    This can either result in a slurry that has a higher viscosity, higher yield stress, higher compressive strength (with attraction), or is less viscous, has a lower yield stress and a lower compressive strength (in the case of repulsion). In terms of permeability, higher levels of attraction between particles typically results in increased permeability due to an increase in the effective particle size caused by the aggregation of fine particles in the slurry. This effect was the primary objective of the use of polymer flocculants in slurry dewatering (either within a thickener, filter, centrifuge or on deposition in a TSF). In the case of flocculant addition in particular, the resultant change in rheology and dewaterability was a strong function of the dose of polymer. It was known that larger doses of flocculant could result in a larger improvement in permeability, but with a stiffer particle network (i.e., increased yield stress at a fixed solids concentration).

99    The changes in both permeability and network strength with increasing levels of flocculation are illustrated in the graphs set out below. In these graphs, permeability and network strength behaviour for three states of flocculation are conceptually depicted. State A represents a material that is unflocculated. State B represents a material that is moderately flocculated. And State C represents a material that is heavily flocculated. As can be seen in the graph on the left, the more flocculated that a material is, the higher its shear or compressive strength at a fixed solids concentration. As can be seen in the graph on the right, the more flocculated the material is, the higher the permeability for a given solids concentration. Typically, a permeability graph as depicted on the right is logarithmic, such that the changes induced by flocculation as illustrated can result in improvements of factors of 10 (or greater) over unflocculated material.

100    Sixth, slurries can exhibit changes in their rheology and de-watering behaviour as a function of the level of shearing they experience. The presence of shear dependency in a slurry can be related to the chemistry, mineralogy, particle shape or presence of additives in the slurry.

101    In particular, for slurries subject to polymer flocculation, the flocculated network generated by the flocculant, is highly shear sensitive such that exposing the slurry to shear can degrade the flocculated network. This degradation is irreversible (without the addition of further flocculant) and would typically lead to reductions in viscosity, yield stress, compressive strength and a significant reduction in permeability.

102    Let me say something further about yield stress at this point. Flocculants increase the yield stress of a mineral slurry. Yield stress is a measure of the strength of the slurry. That is, the ability of the slurry to withstand the application of applied force such as shear.

103    The yield stress of the slurry is critical to both the pumping of the slurry to a deposition area (such as a tailings dam) and the behaviour of the slurry on deposition.

104    Typically, the greater the amount of flocculant used, the greater the yield stress of the slurry at a given concentration, as demonstrated in the diagram set out below. As the concentration of solids in the slurry is increased the slurry becomes less fluid-like and starts to become paste-like (like toothpaste or peanut butter) and ultimately, at high concentration, becomes solid-like (a cake).

105    Pumping a slurry with a higher yield stress will require more energy to pump than a slurry with a lower yield stress. However, as discussed below, pumping the slurry also exposes the slurry to shear forces, which causes flocs to break down and for the yield stress to decrease.

106    Let me now say something about pumpability and shear thinning. The distance between the thickener or treatment plant and the deposition area could vary from tens of metres to many kilometres depending on the particular mine. Therefore the time the thickened tailings were in transit from the thickener or treatment plant to the deposition area could vary from seconds to hours.

107    A common speed at which slurries were pumped was between 1 to 2 metres per second, depending on the material being pumped. Therefore, if the material was being pumped 300 metres the transit time was between 2.5 and 5 minutes. Whereas if the material was being pumped 10 kilometres, the transit time could be in excess of 2.5 hours.

108    However, the pumping of the tailings, particularly over long distances, could cause flocs formed in the tailings to break up and for the tailings to become more fluid with a decreased viscosity (often referred to as “shear thinning”). This shear thinning was a function of the mineralogy of the tailings, turbulence in the outlet pipe, the time that the floc structure was subjected to that turbulence and/or the sensitivity of the floc structure to such shear forces.

109    The distance the slurry is pumped (and therefore transit time) will also influence the amount of shear thinning that occurs. The distance (and therefore transit time) from the mine site to the point of deposition varied according to the mine and mineralogy involved. The distances involved can be measured in kilometres. The transit time from the thickener to the point of deposition could be very short and take only a few minutes or 60 minutes or longer depending on the setup of the mine site.

110    Shear thinning would typically lead to reductions in viscosity, yield stress, compressive strength and a significant reduction in permeability of the tailings on deposition in the deposition area.

111    Consequently, even if the slurry had a yield stress that was suitable for stacking on deposition when it exited the thickener, that yield stress would inevitably be significantly reduced when the slurry was pumped to the deposition area by virtue of the flocs being broken down by shear thinning.

112    Let me say something about holding vessels. One practice undertaken prior to the priority date was to temporarily divert some of the flocculated tailings to a holding vessel before pumping the diverted tailings to the deposition area.

113    Diverting some tailings to a holding vessel was undertaken for a variety of operational and logistical reasons including generation of sufficient material to achieve the required coarse/fine blending requirements or for the addition and conditioning of chemicals or other additives to the tailings which required time. Furthermore, plant logistics may have required a certain volume of tailings to be deposited at a particular time or over a particular timeframe requiring storage or accumulation of tailings in the interim.

114    Further, one could subject liquor released from deposited tailings to further processing to reclaim or re-use any valuable dissolved materials.

115    At this point let me elaborate further on the question of dewatering and various devices.

116    Dewatering screens were a class of dewatering device where solids were retained on a perforated screen, whilst liquid drained through the apertures, enabling dewatering. The aperture size was selected based on the size of the particles in the feed slurry. The drainage was either driven by gravity (a gravity drainage screen) or an acceleration force provided by a vibrating screen (a vibrating dewatering screen).

117    If the feed slurry contained free solids that were smaller than the screen aperture size, the water released from the screen was dirty and would typically require further treatment. A dewatering screen required rapidly dewatering, free-draining solids and as such was typically employed in coarse tailings dewatering.

118    Alternatively, fine particle systems were treated on gravity drainage screens after application of dosages of polymer flocculant. This created a strong, granular, freely draining floc structure that released water rapidly on the screen (typically similar to the structure developed for in line flocculation and belt press filtration). Inclination of the screen resulted in solids movement down the screen, and ploughs were often employed to gently shear/densify the flocs and enhance water release. Alternatively, a screen could be in the form of an inclined rotating cylinder, whereby a gentle tumbling action promoted floc densification and water release. Gravity drainage also formed the critical initial dewatering phase of operation of a belt press filter.

119    Adoption of dewatering screens was characterised by:

(a)    low technical complexity and capital cost, although vibrating screens would often only be one component of the full tailings management system;

(b)    consideration of additional filtration for fines present in water released;

(c)    potential requirements for conveying and trucking to the TSF;

(d)    reducing costs for TSF development and management with increasing ultimate placed solids concentration; and

(e)    improving water efficiency and environmental credentials proportional with the ultimate placed solids concentration.

120    Further, cyclones were commonly used in mineral processing to fractionate particles in a slurry into a coarse and fine fraction. Use of dewatering cyclones was commonly employed at operations where predominantly sand-sized tailings were generated e.g. in the mineral sands industry. A cyclone essentially was a cylindrical vessel with a tapered conical base in which a slurry was tangentially injected such that a swirling flow was generated. Due to ‘centrifugal force’, coarser particles would migrate faster to the outside of the vessel such that they moved downwards and were collected in an underflow stream at the base of the vessel. Fine particles moved in a flow pattern upwards and out of the centre of the cyclone in an overflow stream. Of course, anyone who has a modicum of physics education would know that the concept of “centrifugal force” is a fictitious outward force which is only apparent to observers in a rotating reference frame (e.g. a child on a playground roundabout). Rather, from an inertial reference frame, as materials enter the cyclone, the cyclone wall exerts a centripetal force towards the inside of the cyclone, which forces the slurry to undergo circular motion. Any object moving in circular motion is the subject of a centripetal force towards the centre. Think of it this way. An object in circular motion is accelerating. That is because its velocity is changing. Now its speed may be constant but its direction is changing. As velocity, a vector, is a function of speed and direction, an object in circular motion is changing velocity i.e. accelerating. And that acceleration, also a vector, is towards the centre. Force, also a vector, is a product of mass times acceleration. As the acceleration component (a vector) is towards the centre, with mass as a scalar concept, the force (centripetal force) is towards the centre. Now in the present context as the centripetal force applied is insufficient to keep the larger particles in circular motion, the radius of circular motion for such particles will increase until they migrate towards the outside of the vessel.

121    The natural behaviour of a cyclone was such that the water preferentially reported to the overflow with the fines, and the underflow contained coarse particles at a significantly higher solids concentration than in the feed. This natural dewatering effect could be enhanced by either the operating parameters or cyclone design, to promote enhanced dewatering of the cyclone underflow, such that a stackable, coarse output could be achieved.

122    Some ancillary treatment approach was required to deal with the dilute cyclone overflow stream containing fine material e.g. subsequent thickening or settling pond impoundment.

123    Adoption of cyclones was characterised by:

(a)    low technical complexity and capital cost, however they would typically only be one component of the full tailings management system;

(b)    the requirement of additional thickening / clarification for fines present in overflow;

(c)    reducing costs for TSF development and management with increasing ultimate placed solids concentration; and

(d)    improving water efficiency and environmental credentials proportional with the ultimate placed solids concentration.

124    Further, centrifuges were a dewatering technique whereby a slurry was placed within a rotating vessel which could be either solid (a solid bowl centrifuge) or with some kind of filter medium or screen at the base (basket or screen bowl centrifuge).

125    A wide range of centrifuge designs existed with differing rotational speeds, mechanical methods for solids discharge (e.g. via a helical scroll, scraping blade or plunger) and sometimes with additional vibration to enhance solids dewatering.

126    In general, centrifuges were less commonly used for tailings dewatering than other technologies. Vibrating basket centrifuges were most commonly used in fine coal dewatering, and solid bowl centrifuges were relatively commonly used in dewatering of industrial and municipal water and wastewater sludges, typically after heavy polymer flocculant dosage.

127    Adoption of centrifuges was characterised by:

(a)    moderate technical complexity and capital cost;

(b)    reducing costs for TSF development and management with increasing solids concentration; and

(c)    improving water efficiency and environmental credentials proportional with the dewatered solids concentration.

128    Further, filtration was a dewatering technique where slurry was forced against a semi-permeable filter medium which resulted in retention of slurry solids on the medium as a filter cake, with passage clarified liquid (filtrate) through the medium.

129    A large number of different filtration technologies existed at the priority date such that it is impractical to provide an exhaustive list, but the broadest classification of filter types can be made based on the driving force for separation, which can be as a positive pressure or via application of a vacuum.

130    Pressure filters typically used for tailings dewatering at the priority date were most commonly recessed plate-type pressure filters, although pressure variants of disc and drum filters were also available.

131    The belt press filter was also used for tailings dewatering and involved conditioning of thickener underflow with large doses of flocculant to produce freely dewatering slurry, with a “cottage cheese” structure. This then went through a gravity drainage phase followed by filtration under high pressure between two belts.

132    Successful operation of a belt press filter required the use of sufficiently high doses of flocculant to feed to produce the necessary freely dewatering “cottage cheese” like structure. This was necessary so that the material could be squeezed between the belts rather than being displaced by them.

133    Let me now say something about tailings beaching.

134    Conceptually, beaches can form in two ways. For a homogenous slurry, where solid particles do not rapidly settle out, a beach forms as the slurry stops moving at some point after deposition due to its viscous nature overcoming the level of energy driving the spreading of the slurry. Alternatively, a beach could form due to material settling out from the slurry as it travelled outwards from the deposition point. In some cases, where a wide range of particle sizes were present within a slurry, differential settling rates could exist, with coarser particle settling faster than the finer ones. This could then result in coarser particles being deposited closer to the deposition point, with finer material travelling progressively further down the beach. In extreme cases, the beach may be formed predominantly of coarse material with fines migrating to the decant pond. In situations where separation of the particles from the deposited slurry was the driving force for beach formation, the rate of separation was driven by the particle settling rate (i.e. a measure of permeability), which in turn controlled the beach angle.

135    A schematic illustrating the impact of particle size on separation/settling of solids during deposition is set out below. This illustrates how larger, or denser particles or flocs will tend to be deposited closer to the exit of a discharge pipe than finer particles.

136    A flocculated structure at the point of deposition could enhance beach formation by either:

(a)    binding fines to coarse particles to prevent segregation on the beach; or

(b)    promoting more rapid separation of solids from the carrier fluid.

137    In the case of thickened or paste thickened tailings discharged into a deposition area, it was desirable for the deposited tailings to form a sloped beach in the deposition area.

138    For tailings deposited with perimeter discharge, development of a beach was desirable as it promoted run off of liquid expressed from the tailings into a decant pond for easy recycling. In addition, the integrity of the TSF embankment was also enhanced through the migration of liquid away from the area adjacent to the embankment. TSF embankments were typically not constructed as water retaining facilities due to a higher cost of construction (except in circumstances where a water cover over deposited tailings was required) and as such, the presence of large volumes of water against these structures could lead to structural failure.

139    A further advantage of the development of a beach is that it allows the construction of further embankment walls on top of the beached material when the mine operator wishes to raise the dam wall. This method of construction is termed an “upstream raise”. Adopting this construction approach significantly reduces the cost of raising the dam wall, as the amount of construction material required is significantly reduced. For this to occur, the beached material needs a sufficient level of strength to support the overlying dam wall structure. As can be seen from the diagram below, the relative amount of material required for an “upstream raise” is significantly less than for a “downstream raise” or a “centreline raise”.

140    For the tailings deposited with central discharge, it was also desirable for the development of a sloped beach, which in this case would be a conical shape. The advantages of a sloped beach in such a case are to promote run off of rainfall to maintain the tailings in a dry state, and to allow storage of the maximum amount of tailings within the conical shape without either having to build a high confining embankment or to occupy a large area.

141    Generally, beaching of the tailings allowed for the storage of a greater volume of tailings for a given area of TSF, which was one of the goals of tailings management processes.

THE OPPOSED APPLICATIONS

(a)    Background

142    Let me address some background concerning the disposal of tailings.

143    Generally speaking, until about the mid to late 1950s water was not scarce and there were no restrictions on the dumping of wastes or use of tailings dams. Therefore a mine operator could usually obtain water from any easily available source and dump the tailings whenever convenient. This often meant using water from a river and dumping the wastes back into the river. Typically, mine operators simply deposited the tailings into pits, dams or rivers without further treatment or consideration of the environmental impact of the tailings, and without concern for recovering water from the tailings.

144    Prior to the 1980’s the most commonly used technique for dewatering of tailings involved the use of thickeners to recover some of the water from the tailings. To enhance the separation rate of the solid and liquid within a thickener, the generally accepted practice was to add a flocculant to the feed entering the thickener which aggregated the particles in the thickener and increased their settling rate. As the solids separated from the water in the thickener, clear water was taken from the top of the thickener. The solids removed from the bottom of the thickener were usually pumped in a slurried form to a deposition area. The deposition area could have been an existing mined-out pit, or a purpose built tailings storage facility.

145    A common method for disposing of thickener underflow was to deposit it onto a slope, wall or floor of a deposition area in order to beach the tailings, so that released water flowed to a lower point and could be pumped back to the plant for re-use (tailings beaching). A typical approach to tailings beaching was to deposit thickener underflow onto a slightly sloping surface, which enabled the material to build up on the slope with released water flowing to a lower point where it could be recovered for re-use in the mining process.

146    In the 1980s and 1990s in Australia, mine operators were faced with challenges in relation to environmental issues, water efficiency and limited land availability, and increased regulatory controls. Those factors and good economic reasons forced mine operators to look at ways to improve their tailings disposal processes.

147    As a result of these pressures, in the period leading up to the priority date, the mineral processing industry was focused on improving ways of disposing of tailings. Some objectives in the management of the treatment of tailings were to:

(a)    minimise the amount of land that was taken up by the storage of tailings to create as small a footprint as possible;

(b)    obtain a stable and trafficable deposit;

(c)    maximise recovery of relatively clean water so that the water could be re-used in the plant; and

(d)    rehabilitate the deposited tailings within an acceptable timeframe.

148    Further and in this context, the particular choice of tailings dewatering technique employed for a given operation was strongly influenced by the particular circumstances existing at any mine including:

(a)    land availability and topography;

(b)    water availability;

(c)    environmental restrictions;

(d)    access to power;

(e)    distance to deposition area from plant; and

(f)    available manpower.

149    At the priority date the most commonly used tailings dewatering techniques which involved the use of mechanical dewatering equipment included the use of thickeners/clarifiers, dewatering screens, cyclones, centrifuges, and filtration methods such as belt press filters, all of which involved the use of flocculants.

150    Co-disposal was also a technique used in some cases both to dispose of coarse waste materials and to assist in obtaining a stable deposit of tailings in the deposition area, including in tailings beaching. However, there were well known difficulties involved with co-disposal.

(b)    The invention described in the 785 application

151    The field of the invention is described in the 785 application (p 1 lines 5 to 10) in the following terms:

The present invention relates to the treatment of mineral material, especially waste mineral slurries. The invention is particularly suitable for the disposal of tailings and other waste material resulting from mineral processing and beneficiation processes, including the co-disposal of coarse and fine solids, as a homogenous mixture.

152    The 785 application notes that in some cases the tailings could be back filled into mines. In cases where it was not possible to dispose of the waste in an emptied mine, it was common practice to dispose of the waste material by pumping the aqueous slurry to lagoons, heaps or stacks and allowing it to dewater gradually through the actions of sedimentation, drainage and evaporation. Page 1 lines 26 to 30 states:

For other applications it may not be possible to dispose of the waste in a mine. In these instances, it is common practice to dispose of this material by pumping the aqueous slurry to lagoons, heaps or stacks and allowing it to dewater gradually through the actions of sedimentation, drainage and evaporation.

153    The 785 application notes the environmental pressures to minimise the allocation of new land for disposal and to more effectively use the existing waste areas. A related environmental pressure was the efficient re-use of water in the mining process. Page 2 lines 1 to 4 states:

There is a great deal of environmental pressure to minimise the allocation of new land for disposal purposes and to more effectively use the existing waste areas. One method is to load multiple layers of waste onto an area to thus form higher stacks of waste.

154    The 785 application notes that it is desirable to have a treatment which provides a more rapid release of water from the deposited material and that the concentrated solids are held in a manner that prevents both segregation of any coarse and fine fractions and contamination of the released water, whilst minimizing the impact on the environment. Page 3 line 29 to page 4 line 2 states:

It would therefore be desirable to provide treatment which provides more rapid release of water from the suspension of solids. In addition it will be desirable to enable the concentrated solids to be held in a convenient manner that prevents both segregation of any coarse and fine fractions, and prevents contamination of the released water whilst at the same time minimises the impact on the environment.

155    The 785 application recognises that one method of reducing the area of deposition was to form stacks of “rigidified waste”. One “difficulty” identified in the 785 application was to ensure that the new waste flowed over previously “rigidified” waste, remained within the waste area boundaries, formed a stack and consolidated to support multiple layers without collapsing or overflowing. Page 2 lines 3 to 8 states:

One method is to load multiple layers of waste onto an area to thus form higher stacks of waste. However, this presents a difficulty of ensuring that the waste material can only flow over the surface of previously rigidified waste within acceptable boundaries, is allowed to rigidify to form a stack, and that the waste is sufficiently consolidated to support multiple layers of rigidified material, without the risk of collapse or slip.

156    The 785 application describes the common use of flocculants to assist in the disposal of tailings through the process of flocculation in a thickener so as to give higher density to the underflow and assist in the recovery of water. Page 2 lines 16 to 18 states:

These solids are often concentrated by a flocculation process in a thickener to give a higher density underflow and to recover some of the process water.

157    The 785 application also recognises that SDITB had been used to improve the compaction of the fine waste material and clarity of the recovered water. But the 785 application asserts that such processes applying flocculants at “conventional doses” had produced little or no benefit. Page 3, lines 21 to 27 states:

Attempts have been made to overcome all the above problems by treating the feed to the tailings dam using a coagulant or a flocculant to enhance the rate of sedimentation and/or improve the clarity of the released water. However, this has been unsuccessful as these treatments have been applied at conventional doses and this has brought about little or no benefit in either rate of compaction of the fine waste material or clarity of the recovered water.

158    Dr Farrow acknowledged that the reference to “feed to the tailings dam” in the 785 application encompassed thickener underflow. As he said, the most common way of feeding materials to a tailings dam was where the material had previously gone through a thickener.

159    The 785 application refers to EP-O-388-108 (the Moody patent). This is a patent with G Moody as the inventor filed by Allied Colloids Ltd (subsequently acquired by Ciba) on 12 March 1990, although asserting an earlier priority date. The Moody patent discloses a process of secondary dosing involving the addition of a water insoluble flocculant and “allowing the material to stand and then allowing it to rigidify and become a stackable solid”. The 785 application notes that this prior art process disadvantageously requires high doses of flocculant “in order to achieve a sufficiently rigidified material”. Page 5 lines 5 to 14 states:

EP-A-388108 [sic] describes adding a water-absorbent, water-insoluble polymer to a material comprising an aqueous liquid with dispersed particulate solids, such as red mud, prior to pumping and then pumping the material, allowing the material to stand and then allowing it to rigidify and become a stackable solid. The polymer absorbs the aqueous liquid of the slurry which aids the binding of the particulate solids and thus solidification of the material. However this process has the disadvantage that it requires high doses of absorbent polymer in order to achieve adequate solidification. In order to achieve a sufficiently rigidified material it is often necessary to use doses as high as 10 to 20 kilograms per tonne of mud.

160    The 785 application (p 5 line 23) also refers to a prior art process which is described as WO-A-96/05146 (the Pearson patent). This is a patent filed by Cytec in 1995. Cytec was then a major flocculant supplier. The Pearson patent discloses a process of SDITB which involved the addition of a water soluble flocculant “dispersed in a continuous oil phase with the slurry” (p 5 line 25). This is a reference to a water-in-oil emulsion. The 785 application asserts that it is a requirement of the Pearson patent that the flocculant is not inverted and added to the slurry as an aqueous solution. At page 5 lines 25 to 29 it is stated:

Preference is given to diluting the emulsion polymer with a diluent, and which is preferably in a hydrocarbon liquid or gas and which will not invert the emulsion. Therefore it is a requirement of the process that the polymer is not added in to the slurry as an aqueous solution.

161    The 785 application also refers to the Gallagher patent that I mentioned in my introduction filed by Ciba in 2001. The Gallagher patent discloses a process of SDITB in which the treated tailings are pumped as a fluid and then allowed to stand and rigidify. The rigidification is achieved by introducing into the tailings a water soluble flocculant in the form of a dry powder (particles) which has an intrinsic viscosity of at least 3 dl/g into the suspension.

162    The 785 application describes the importance of using a water soluble flocculant in a powder form in the Gallagher patent as follows (p 6 lines 9 to 11):

The importance of using particles of water soluble polymer is emphasised and it is stated that the use of aqueous solutions of the dissolved polymer would be ineffective.

163    Now the Gallagher patent states (pages 3 and 14) that:

We have surprisingly found that the presence of water soluble polymers applied in the form of particles actually enables the material to remain fluid and pumpable during the pumping stage but results in rapid loss of fluidity and rigidification on standing.

…

It is surprising that the process according to the invention forms a product which rigidifies far better than alternative treatments, for instance the use of water swellable, water swellable polymers or pre-formed solutions of water soluble polymers.

164    Contrastingly, the 785 application states (p 7 lines 26 to 29):

We have unexpectedly found that the addition of the aqueous solution of polymer to the material does not cause instant rigidification or substantially any settling of the solids prior to standing.

165    It is well apparent that the form in which the flocculant is added to the tailings, namely, a water soluble flocculant in aqueous solution, is an essential feature of the claimed invention.

166    The 785 application (p 6 lines 19 to 23) describes an objective of the claimed invention as finding a more suitable method of treating coarse and/or fine particulate waste material from mineral sands, alumina or other mineral processing operations in order to provide a better release of fluids and a more effective means of disposing of the concentrated solids. The 785 application notes that the claimed invention may be used on tailings slurries that consist of only fine particles or a mixture of fine and course particles (p 8 lines 6 and 7).

167    The 785 application discloses that the claimed invention may be performed in relation to a wide range of materials and mineralogies, including gold slimes, mineral sands, coal, red mud, nickel, silver and iron ore. Further, the only mineral type which is the subject of a specific claim is mineral sands. Further, the only field trials in the Examples are in relation to mineral sands. Page 8 lines 22 to 27 states:

The material particles are usually inorganic and/or usually a mineral. Typically the material may be derived from or contain filter cake, tailings, thickener underflows, or unthickened plant waste streams, for instance other mineral tailings or slimes, including phosphate, diamond, gold slimes, mineral sands, tails from zinc, lead, copper, silver, uranium, nickel, iron ore processing, coal, or red mud.

168    The 785 application states that the most effective point of addition of the flocculant depends upon the substrate and the distance from the thickener to the deposition area. If the outlet pipe is relatively short, with the transit time being correspondingly short, then it may be advantageous to add the flocculant close to the thickener. Conversely, if the deposition area is remote from the thickener, with the transit time being correspondingly long, then it is desirable to add the flocculant closer to or at the discharge point. Page 14 lines 10 to 17 states:

The most effective point of addition will depend upon the substrate and the distance from the thickener to the deposition area. If the conduit is relatively short any may be advantageous to dose the polymer solution close to where the material flows from the thickener. On the other hand, where the deposition area is significantly remote from the thickener in may be desirable to introduce the polymer solution closer to the outlet. In some instances in may be convenient to introduce the polymer solution into the material as it exits the outlet.

169    The 785 application states (p 14 lines 5 to 10) that:

A suitable and effective rigidifying amount of the water-soluble polymer solution can be mixed with the material prior to a pumping stage … Alternatively, the polymer solution can be introduced and mixed with the material during a pumping stage or subsequently.

170    The 785 application also states that, in one form of the claimed invention, the treated material is transferred to a settling area, such as a tailings dam or a lagoon (p 16 line 32 to p 17 line 1).

171    The 785 application states that (p 13 lines 19 to 22):

The aqueous polymer solution may be added in any suitable concentration. It may be desirable to employ a relatively concentrated solution, for instance up to 10% or more based on weight of polymer in order to minimise the amount of water introduced into the material.

172    The 785 application then indicates that it will usually be desirable to add the flocculant solutions at lower concentrations to facilitate the distribution of the flocculant throughout the material (p 13 lines 22 to 25).

173    Suitable dose ranges for performing the claimed invention are identified as ranging from 10 grams to 10,000 grams per tonne (g/t) of material solids with preferred ranges of 30 to 3,000 g/t and more preferred ranges from 60 to 200 or 400 g/t (p 8 lines 16 to 20).

174    The release of liquor is a preferred feature of the claimed invention, such liquor containing “significantly less solids” and being suitable for recycling in the process (p 16 lines 9 to 18). The 785 application therefore makes clear that it is not necessary for the effective working of the claimed invention that all solids in the treated tailings be captured in the stacked material.

175    The 785 application contains 13 examples. Examples 1 to 8 involve slump tests on various different selections of flocculants on different mineral slurries. Examples 9 to 11 are laboratory evaluations of various flocculants. Examples 12 and 13 include a plant evaluation using tails from a mineral sands process.

176    Example 1 involves slump tests using a tailings slurry obtained from a mineral sands operation. The results of the slump tests are provided in Table 3. The 785 application then notes that: “The increased rigidification of the mineral tailings through the addition of the water soluble polymer is evident by the reduced slump radius and increased stacking height compared to the untreated material” (p 21 lines 2 to 6).

177    Examples 1 to 11 involve a comparison with thickener underflow that was not treated in any way to assess the increased rigidification achieved by the addition of water soluble flocculant in aqueous solution (see the results reported in Tables 2 to 19).

178    In Example 12, laboratory slump tests were conducted on a combined fine and coarse tailings from a mineral sands operation. Following these tests, a plant evaluation was carried out. The 785 application states that “[b]ased on the above laboratory evaluation, a dosing point close (20 metres or 11 seconds) to the discharge point was chosen to minimize shearing…” (p 35 lines 15 to 17). Figure 5 (untreated) and Figure 6 (treated) show the discharge of the mineral sands tailings the subject of the plant evaluation.

179    Example 13 also involves laboratory and plant evaluations on a combined fine and coarse tailings from a mineral sands operation. The 785 application states that “[t]he combined waste material is pumped to a series of pits that are filled sequentially and re-vegetated afterwards” (p 38 lines 8 to 10).

180    In Example 13, in one case product was added before the small centrifugal pump. The result was an improved slump angle and much greater release of water from the slurry (p 38 lines 18 to 21). The dosing point was then modified to be added directly after the centrifugal pump. The dosage was reduced, with this alternative position achieving similar results to the first dosing point (p 39 lines 2 to 4).

(c)    The claims of the 785 application

181    The 785 application (as amended) makes 29 claims. These claims are expressed as follows:

1.    A process of improving rigidification of a material whilst retaining the fluidity of the material during transfer in which the material comprises an aqueous liquid with dispersed particulate solids that is transferred as a fluid to a deposition area, then allowed to stand and rigidify, by combining with the material during transfer an effective rigidifying amount of an aqueous solution of a water-soluble polymer having an intrinsic viscosity of at least 5 dl/g (measured in IM NaCI at 25℃), in which the process comprises co-disposal of coarse and fine solids as a homogenous mixture.

2.    A process according to claim 1 in which the water soluble polymer has an intrinsic viscosity of at least 5 dl/g and is formed from ethylenically unsaturated water-soluble monomer or blend of monomers.

3.    A process according to claim 1 or claim 2 in which the water soluble polymer is anionic.

4.    A process according to claim 3 in which the polymer is formed from monomer(s) selected from the group consisting of (meth)acrylic acid, allyl sulphonic acid and 2-acrylamido-2-methyl propane sulphonic acid as the free acids or salts thereof, optionally in combination with non-ionic co-monomers, selected from the group consisting of (meth)acrylamide, hydroxy alkyl esters of (meth)acrylic acid and N-vinyl pyrrolidone.

5.    A process according to claim 1 or claim 2 in which the water soluble polymer is non-ionic.

6.    A process according to claim 5 in which the polymer is formed from monomer(s) selected from the group consisting of (meth) acrylamide, hydroxyl alkyl esters of (meth) acrylic acid and N-vinyl pyrrolidone.

7.    A process according to claim 1 or claim 2 in which the water soluble polymer is cationic.

8.    A process according to claim 7 in which the polymer is formed from monomer(s) selected from the group consisting of dimethyl amino ethyl (meth) acrylate-methyl chloride, (DMAEA.MeCI) quat, diallyl dimethyl ammonium chloride (DADMAC), trimethyl amino propyl (meth) acrylamide chloride (ATPAC) optionally in combination with non-ionic co-monomers, selected from the group consisting of (meth) acrylamide, hydroxy alkyl esters of (meth) acrylic acid and N-vinyl pyrrolidone.

9.    A process according to any one of claims 1 to 8 in which the dispersed particulate solids are mineral.

10.    A process according to any one of claims 1 to 9 in which the process comprises the disposal of mineral slurry residues from a mineral processing operation.

11.    A process according to any one of claims 1 to 10 in which the process provides a heaped geometry.

12.    A process according to any one of claims 1 to 11, in which the material is derived from the tailings from a mineral sands process.

13.    A process according to any one of claims 1 to 12 in which the dispersed particulate solids have particle sizes less than 100 microns, in which preferably at least 80% of the particles have sizes less than 25 microns.

14.    A process according to any one of claims 1 to 13 in which the dispersed particulate solids has a bimodal distribution of particle sizes comprising a fine fraction and a coarse fraction, in which the fine fraction peak is substantially less than 25 microns and the coarse fraction peak is substantially greater than 75 microns.

15.    A process according to any one of claims 1 to 14 in which the material has a solids content in the range 15% to 80% by weight, preferably in the range 40% or 50% to 70% by weight.

16.    A process according to any one of claims 1 to 15 comprising flocculating an aqueous suspension of solids in a vessel to form a supernatant layer comprising an aqueous liquor and an underflow layer comprising thickened solids forming the material, separating the supernatant layer from the underflow, wherein the underflow containing the particulate material flows from the vessel and, in which the material is then pumped to a deposition area where it is allowed to stand and rigidify, and wherein the effective rigidifying amount of the aqueous solution of the water-soluble polymer is mixed with the material after flocculating the suspension and before the material is allowed to stand.

17.    A process according to claim 16 in which wet or dry coarse particles are added to the underflow from the vessel either before or during the addition of an effective rigidifying amount of the water soluble polymer.

18.    A process according to claim 16 or 17 in which the material is transferred to a holding vessel prior to being pumped to the deposition area.

19.    A process according to any of claims 1 to 18 in which the process provides a heaped geometry and co-immobilises the fine and coarse fractions of the solids in the material and water released has a higher driving force to separate it from the material by virtue of hydraulic gravity drainage.

20.    A process according to any of claims 1 to 19 in which the material is pumped to an outlet, where it is allowed to flow over the surface of previously rigidified material, wherein the material is allowed to stand and rigidify to form a stack.

21.    A process according to any one of claims 1 to 20 in which the effective rigidifying amount of the aqueous solution of the water-soluble polymer is mixed with the material prior to a pumping stage.

22.    A process according to any of claims 1 to 20 in which the effective rigidifying amount of the aqueous solution of the water-soluble polymer is mixed with the material during or subsequent to a pumping stage.

23.    A process according to any claims 1 to 21 in which the effective rigidifying amount of the aqueous solution of the water-soluble polymer is mixed with the material as it exits the outlet.

24.    A process according to any of claims 1 to 23 in which the material is dewatered during rigidification, releasing liquor.

25.    A process according to claim 24 in which the liquor is recycled to a mineral processing operation.

26.    A process according to claim 24 or 25 in which the clarity of the liquor is improved by the addition of an aqueous solution of water-soluble polymer.

27.    A process according to any of claims 24 to 26 in which the liquor contains dissolved valuable materials and, in which the liquor is subjected to further processing to reclaim or re-use the valuable materials.

28.    Use of an aqueous solution of a water-soluble polymer having an intrinsic viscosity of at least 5 dl/g (measured in 1 M NaCI at 25℃), in a process in which material comprising aqueous liquid with dispersed particulate solids is transferred as a fluid to a deposition area, then allowed to rigidify, for the purpose of improving rigidification whilst retaining fluidity of the material during transfer, in which the process comprises co-disposal of coarse and fine solids as a homogenous mixture.

29.    A process of improving rigidification of a material whilst retaining the fluidity of the material during transfer according to claim 1 substantially as hereinbefore described with reference to the examples.

182    A number of observations may be made in relation to the scope of claim 1 of the 785 application which contains the following integers:

A process of improving rigidification of a material whilst retaining the fluidity of the material during transfer

in which the material comprises an aqueous liquid with dispersed particulate solids that is transferred as a fluid to a deposition area, then allowed to stand and rigidify,

by combining with the material during transfer

an effective rigidifying amount of

an aqueous solution of a water-soluble polymer having an intrinsic viscosity of at least 5 dl/g (measured in IM NaCI at 25℃),

in which the process comprises co-disposal of coarse and fine solids as a homogenous mixture.

183    First, the process of claim 1 is not limited by the material having any particular solids content. The only limitation as to the solids content of the material is introduced in claim 15 which limits the process to materials having a solids content of 15 to 80%.

184    Second, the process of claim 1 is not limited by reference to a dose range for the flocculant. The claim requires an “effective rigidifying amount”. This refers to the amount of high molecular weight flocculant solution needed to cause the material to “rigidify”. Although the claim does not specify what this amount might be, the 785 application states that a “suitable” dose will range from 10 grams to 10,000 g/t of material solids.

185    Third, claim 1 requires that the aqueous solution of a water-soluble flocculant be added “during transfer”. It does not appear to be in dispute that this term refers to the addition of flocculant to the thickener underflow and encompasses the flocculant being added at any point between the point at which the underflow is discharged from the thickener to the point at which the treated material is discharged into the deposition area.

186    Fourth, claim 1 requires the deliberate combining of coarse and fine materials.

187    Fifth, claim 1 encompasses the flocculant being added either before, during or after the coarse and fine materials are combined in the thickener underflow.

188    Finally, the process of claim 1 requires that the treated material be allowed to “stand and rigidify” in the deposition area. It does not exclude subsequent removal of the rigidified material or the material standing and rigidifying on a physical structure in the deposition area.

189    Claims 2 to 8 depend on claim 1 and introduce limitations concerning the chemistry of the water soluble flocculant.

190    Claims 9 and 10 limit the material being treated to minerals.

191    Claim 11 refers to a process which provides a heaped geometry.

192    Claims 12 to 15 limit the material being treated by reference to mineralogy (mineral sands), particle size, bimodal distribution of particle size and solids content.

193    Claim 16 is a dependent claim which requires that the tailings being treated are underflow from a thickener.

194    Claim 17 introduces the limitation of adding wet or dry coarse particles to the underflow before or after the addition of the water soluble flocculant.

195    Claim 18 introduces the limitation of the material being transferred to a “holding vessel” before being pumped to the deposition area.

196    Claim 19 limits the process of claim 1 by further requiring that the process provide a “heaped geometry” and co-immobilisation of the fine and coarse fractions of the solid material, with the water released having a higher driving force to separate it from the material by virtue of hydraulic gravity drainage.

197    Claim 20 requires that the material when deposited is allowed to flow over the surface of previously rigidified material and is allowed to stand and rigidify to form a stack.

198    Claims 21 to 23 introduce limitations concerning the mixing of the flocculant with the material prior to, during or subsequent to pumping or as the material exits the outlet.

199    Claim 24 requires the material to be dewatered during rigidification, releasing liquor.

200    Claims 25 to 27 introduce limitations concerning the liquor which is released from the material being treated.

201    Claim 28 is an independent claim which is not relevantly different in scope to claim 1. It claims the use of an aqueous solution of a water soluble flocculant having an intrinsic viscosity of at least 5 dl/g (measured in 1M NaCL at 25℃), in a process in which material comprising aqueous liquid with dispersed particulate solids is transferred as a fluid to a deposition area, then allowed to rigidify, for the purpose of improving rigidification whilst retaining fluidity of the material during transfer, in which the process comprises co-disposal of coarse and fine solids as a homogenous mixture.

202    Claim 29 is an omnibus claim for the process according to claim 1, limited to the examples in the 785 application.

(d)    The claims of the 568 application

203    The body of the 568 application is substantially similar to the body of the 785 application and contains no significant differences of relevance to the present discussion. Accordingly, it is not necessary to set it out. The 568 application (as amended) makes 35 claims. It is not necessary to set them out save for claim 1 which stipulates:

1.    A process of improving rigidification of a material whilst retaining the fluidity of the material during transfer, in which the material comprises an aqueous liquid with dispersed particulate solids that is transferred as a fluid to a deposition area, then allowed to stand and rigidify, the process comprising:

combining aqueous suspensions of fine and coarse particulates for the purpose of co-disposal to form the material;

mixing of the aqueous suspensions into a homogeneous slurry; and

during or after mixing of the aqueous suspensions, combining with the material during transfer an effective rigidifying amount of an aqueous solution of a water-soluble polymer having an intrinsic viscosity of at least 5 dl/g (measured in 1 M NaCl at 25°C).

204    Claim 1 accordingly contains the following integers:

a process of improving rigidification of a material whilst retaining the fluidity of the material during transfer;

in which the material comprises an aqueous liquid with disbursed particulate solids that is transferred as a fluid to a deposition area, then allowed to stand and rigidify,

the process comprising:

combining aqueous suspensions of fine and course particulates for the purpose of co-disposal to form the material;

mixing of the aqueous suspensions into a homogeneous slurry; and

during or after mixing of the aqueous suspensions, combining with the material during transfer an effective rigidifying amount of an aqueous solution of a water-soluble polymer having an intrinsic viscosity of at least 5 dl/g (measured in 1M NaCl at 25℃).

205    Claim 2 describes a process which involves treating material which is the “underflow from a thickener”. A flocculant is combined with that material and transferred to a deposition area. The process comprises the co-disposal of coarse and fine solids as a homogenous mixture.

206    Claim 3 describes a process which involves treating material which is the “underflow from a thickener”. A flocculant is combined with that material at a “selected dosing point” and transferred to a deposition area. The process comprises the co-disposal of coarse and fine solids as a homogenous mixture.

207    Claim 4 is dependent on claim 3 and adds the requirement that the dosing point to be “near an outlet where the material is discharged in the deposition area”.

208    Claim 5 is dependent on claim 3 and adds the requirement that the water-soluble flocculant is added “to a conduit containing a flow of the material”. Page 7a of the 568 application discloses that “[t]he conduit is any convenient means for transferring the material to the deposition area and may for instance be a pipe or a trench”.

209    Claim 6 is dependent on claim 3 and adds the requirement that the flocculant has an intrinsic viscosity of at least 5 dl/G.

210    Claims 7 to 11 introduce limitations concerning the solids content of the material being treated.

211    Claims 12 to 18 introduce limitations concerning the properties of the flocculant.

212    Claims 19 to 21 introduce limitations on the source of the material being treated.

213    Claims 22 to 24 limits the material being treated by particle size and particle size distribution.

214    Claim 25 is a dependent claim which is expressed in similar terms to claim 1, given that the words “during transfer” in claim 1 of the 785 application means that the material being treated is thickener underflow.

215    Claim 26 is dependent on claim 25 and adds the requirement that coarse particles (wet or dry) are added to the underflow before or during the addition of the flocculant.

216    Claim 27 is dependent on claim 25 or claim 26 and adds the requirement that the material is transferred to a “holding vessel” before being pumped to the deposition area.

217    Claim 28 is dependent on any of the preceding claims and adds the requirement that the material is discharged from an outlet and allowed to flow over the surface of previously rigidified material then stand and rigidify to form a stack.

218    Claims 29 and 30 are dependent on any of the preceding claims and add the requirement that the mixing of the flocculant with the material being treated occurs “during or subsequent” to pumping (claim 29) or as the material “exits the outlet” (claim 30).

219    Claims 31 to 33 introduce limitations concerning recycling the water/liquor released from the material being treated recovering valuable materials contained in the water/liquor.

220    Claim 34 is an omnibus claim.

WITNESSES

(a)    SNF’s witnesses

221    Dr de Kretser is a technical engineering consultant in the areas of tailings and waste sludge management, solid-liquid separation, chemical conditioning, heap leach hydrodynamics, suspension rheology and the development and execution of laboratory and site based testing programs in these areas. He has a blend of specialised theoretical and practical experience gained across a range of industries including mining and waste water management in the period 1990 to date.

222    His doctoral thesis at the University of Melbourne completed in 1995 was in respect of “the compression dewatering and rheology of slurried coal mining tailings”. His area of research speciality was the “characterisation of the permeability and compressibility properties of materials” and developing techniques for understanding the behaviour of materials including how flocculation or particle size changes that behaviour. The focus of his research was on filtration methods, sedimentation methods, gravity permeation methods, all of which were methods which probed the permeability and compressibility of flocculated sediments over a range of solids concentrations. Dr de Kretser used that information in the context of optimising any one of those solid/liquid separation processes, ranging from settling through to consolidation in a tailings dam or filtration. I will return to discuss his thesis later as it has relevance to some of his evidence.

223    In the period 1996 to 2003, Dr de Kretser worked at the University of Melbourne, where he worked on numerous collaborative projects with industry, including various Australian Minerals Research Association (AMIRA) projects. His numerous collaborative projects involved site work and practical application in the field of research and development. He worked on many of the projects undertaken by AMIRA in the period 1996 to 2003, including:

(a)    AMIRA project 527 which was concerned with flocculating tailings in the context of the Bayer Process. This work involved laboratory, pilot scale and large scale field work at alumina sites in Western Australia and Queensland, including working on thickeners and examining the properties of the thickener underflow “going into a tailings deposition area”.

(b)    AMIRA project 266 which was concerned with improving thickener technologies.

224    Before the priority date, Dr de Kretser was involved in a number of projects which concerned the disposal of coarse and fine materials in mineral tailings, and in particular was aware:

(a)    through his work in the alumina industries of issues with coarse and fine materials through the thickening process;

(b)    of the coarse and fine tailings disposal and co-disposal work that was being undertaken in the oil sands industry in Canada; and

(c)    of the problems that arise when coarse and fines segregate during deposition and also during transport.

225    Following the priority date, Dr de Kretser continued to work at the University of Melbourne where he continued to collaborate on research based projects with industry. As part of his work for the University both before and after the priority date Dr de Kretser visited a number of mineral processing plants, including alumina refineries, copper, uranium, lead, zinc and coal processing plants. In 2011 Dr de Kretser left the University and was employed by Rio Tinto as a principal advisor in waste water and tailings for 4.5 years. As a result of that work, Dr de Kretser managed laboratory and field testing programs including in relation to dewatering technologies, dry and semi-dry tailings disposal, and inline flocculation.

226    Mr Russell Schroeter has been the Managing Director of SNF since 2002. Mr Schroeter holds a bachelor degree in Applied Science from the Gordon Institute of Technology. Mr Schroeter has worked in the field of mine tailings disposal since 1978 including for Nalco Chemical Company (Nalco). Between 1978 and the priority date, Mr Schroeter regularly visited mine sites to observe their tailings disposal processes and identify potential uses for flocculant in those processes. In particular, Mr Schroeter visited numerous mines around Australia which used thickeners in the treatment of tailings comprising a range of mineral types including coal, alumina, gold, nickel, mineral sands, copper, lead, zinc and uranium. Mr Schroeter has listed 29 mine sites around Australia which he personally visited before the priority date. Between 1994 to April 2002, Mr Schroeter worked for Nalco in New Zealand and then in Singapore. Although Mr Schroeter’s primary role concerned the sale of flocculants in the pulp and paper industry, he regularly attended internal meetings and remained aware of Nalco’s work in the mining industry during that time. He also continued to have some direct involvement in the mining industry. For example, Mr Schroeter became aware of the Pearson patent in around 1996, in the context of trying to sell flocculants to the Waihi gold mine in New Zealand.

227    Dr Nicholas Clarke is currently the Manager Metallurgy in the international division at AngloGold Ashanti Australia and has a PhD in mineral processing from Leeds University. Dr Clarke has over 40 years’ experience in the mineral processing industry, which included working for Iluka Resources Ltd (Iluka), which had been the majority shareholder of Consolidated Rutile Limited (CRL), between 2002 and 2006 as a principal process engineer within the R&D group at Iluka.

228    Mr Carl Buckland is the Operation Manager for Boral’s South-East Queensland Quarries and in the period 1999 to 2002, was the Assistant Quarry Manager at Boral’s Stapylton Quarry in Queensland.

229    Mr Peter Holtzman was employed during the period 1992 until May 2015 by Cable Sands (WA) Pty Ltd (Cable Sands) as a metallurgical technician. He is now retired.

230    Mr Michael Schmidt is self-employed. Mr Schmidt has a Diploma in Applied Science from North-West TAFE, Tasmania. From 1997 to 2009 Mr Schmidt was employed by Nalco as a Technical Sales Representative. Between 2010 and March 2016, he was employed by SNF as an account manager. In both of his roles he promoted and sold flocculants for use in treatment processes including the OreBind process, which I will describe and elaborate on later.

231    Mr Ronald Coleman has a Bachelor of Science (Tech) in Chemical Engineering and has been involved in the mining industry for over 30 years. His specific expertise is in the field of waste treatment and water recovery including advising on and developing processes for dealing with and recovering water from waste materials including at the Londonderry Mine in around 1984.

232    Mr Peter Woolley is an account manager employed by Integrated Water Management Pty Ltd. He has a Bachelor of Science degree from the University of New South Wales. Mr Woolley was employed by Nalco (and its predecessor) for 28 years. He was involved in sales and marketing for various applications including applications in the treatment of wastes in the mining industry. This involved regularly visiting mining sites, including the Londonderry Mine in New South Wales, and observing the processes used to treat and dispose of mining waste.

233    Mr Jim Cigulev has been a Technical Services Superintendent at Doral Mineral Sands for around 14 years, and has more than 32 years’ experience in the mining industry. Mr Cigulev has a Bachelor of Science degree with a major in chemistry from the University of Western Australia. In the period 1996 to 1999, Mr Cigulev was a metallurgist working for BHP at its Beenup Mine in Western Australia. In 1999 to March 2002, Mr Cigulev was a contract process engineer working for Iluka.

234    Mr Daniel Bembrick worked for Allied Colloids (which became Ciba) as a laboratory analyst for a number of years assisting with trials and laboratory work, which included analysing the effectiveness of flocculants and performing quality control tests on flocculants. Mr Bembrick has a Bachelor of Science majoring in Chemistry from Charles Sturt University. Mr Bembrick worked for Ciba from 1997 until April 2003, and then for SNF from November 2003 to January 2012 as an account manager. Mr Bembrick now works as a process consultant / sales manager for the BTX Group, which is a distributor of water treatment chemicals. His experience also included visiting mines on a regular basis for the purposes of attempting to sell flocculants to mine operators.

235    Ms Janine Herzig graduated from the University of Queensland in 1992 with a Bachelor of Engineering (Honours) in metal processing. She has approximately 25 years’ experience in the Field, including as a Plant Metallurgist at CRL’s mineral sand mine at Yarraman on North Stradbroke Island in Queensland for most of the time between August 1995 and February 2003. From February 2003 until April 2005, Ms Herzig was the principal metallurgist for Iluka.

236    All of these witnesses were cross-examined. SNF also tendered evidence from Dr John Ralston and Mr Brett Wroth but they were not cross-examined.

237    In general, many of the witnesses called by SNF gave their oral evidence truthfully, and to the best of their ability in circumstances where the events in question had often occurred decades earlier. But there were significant parts of their oral evidence that departed from their affidavit evidence, and reconstruction was manifest. Let me give some examples.

238    Each of Mr Holtzman, Mr Buckland, Mr Schroeter and Mr Cigulev sought to give truthful evidence when cross-examined, but in many instances their oral evidence significantly departed from their affidavit evidence.

239    The affidavit of Mr Buckland asserted that “[t]he process we implemented was to dewater the tailings in the impoundment area and there was definitely no further mechanical dewatering step. This material was dewatered on deposition and clear water was captured in the impoundment area. The excavator was subsequently used after the material had dewatered to move it to another location for ultimate disposal. … The material which was excavated out of the pit had very little water in it”. In contrast, his oral evidence was that “an essential component” of the process was the use of a digger, which would invariably “collect some water because … there was nowhere for the water to go out of the silt pond” (Mr Buckland qualified that although “[t]he pond was not full of water … there was always water left in the pond”), and that consideration was given to the use of a screw classifier instead of a digger and it is safe to assume that this is because the treated material was not sufficiently or adequately dewatered.

240    Mr Holtzman asserted in his affidavit evidence in the context of SNF’s allegations of anticipation that he had considered “collectively” four documents sent between Nalco and Cable Sands in 2002 that were said to disclose the process described in the opposed applications and that he recalled the precise details of conversation/s he had with a Nalco representative around the same time that the documents were created. But when cross-examined, there was doubt about him seeing one document. Further, he did not have any recollection of reading the documents together, although the three documents he read were “linked” in his mind, and that he did not have a recollection of the specific conversation(s) alluded to in his affidavit. Mr Holtzman was nevertheless an honest witness.

241    The affidavit of Mr Schroeter asserted immediately under the heading “secondary flocculation” and without any reference to mechanical dewatering, that people in the field knew, at the priority date, “that it was advantageous to add flocculant at more than one point in the tailings disposal process”. But when cross-examined, Mr Schroeter clarified that in his personal experience he had “only added it [flocculant] upstream of belt presses and high-speed centrifuges” and that, as at the priority date, people reporting to him within SNF only had experience with secondary dosing “upstream of some form of mechanical dewatering device”. But generally speaking I found Mr Schroeter to be very frank and commercial.

242    The affidavit of Mr Cigulev asserted that “The process used at Beenup was a co-disposal process”. Contrastingly, when cross-examined his evidence was “we were trying to remove the sand. So there was no conscious – you know, decision to add sand”. Earlier he had said “the process was inefficient and sand was in there due to that inefficiency”. I thought that Mr Cigulev was fudging some aspects of his evidence.

243    Mr Woolley and Mr Coleman sought to give truthful evidence when cross-examined regarding their recollections of events at the Londonderry mine. But for the reasons I have discussed elsewhere, there are some difficulties with their evidence.

244    Mr Woolley and Mr Coleman previously gave evidence in the 2008 proceedings regarding their work in 1980 and 1984 at the Londonderry mine. But their evidence before me conflicted in various respects with the evidence they had given earlier in the 2008 proceedings.

245    Both Mr Woolley and Mr Coleman confirmed that they gave their new evidence before me without obtaining any further materials to the materials relied upon to prepare their affidavits in the 2008 proceedings to assist them to recall events occurring more than 30 years earlier. Moreover, they had visited numerous mine sites in the decades after their work at Londonderry. Cross-examination revealed that their evidence was in some respects unreliable, and involved an attempt to reconstruct what they thought might have happened at Londonderry, by reference to photographs, videos, and documents they had subsequently reviewed over the ensuing decades, as well as conversations with one another. I agree with BASF that the best evidence of what occurred at Londonderry is not the reconstructions of Mr Woolley and Mr Coleman, but the three photographs adduced in evidence. These photographs, taken in 1981, were of the “super flocculation” process working at Londonderry installed by Mr Woolley. They were attached to an affidavit of Mr Woolley filed in the 2008 proceedings.

246    Further, Mr Schmidt sought to give truthful evidence regarding his experience with the OreBind process and the trial work he undertook at Ernest Henry. But some aspects were reconstruction. Other aspects I thought were beyond his expertise.

247    As with many of SNF’s witnesses, it became clear during cross-examination that his affidavit did not in many respects accurately reflect his evidence. Further, he gave his evidence after he had watched a promotional video made by Nalco in 2011 regarding the OreBind process, which he assumed to be the same as the process he had promoted in 1999 and which he relied upon to assist him to describe the OreBind process. But this placed the reliability of his evidence on an uncertain footing, particularly given his concession that he had not witnessed the implementation of the process depicted in the 2011 video as at the priority date. Moreover, the description given of the Ernest Henry testwork in his affidavit had some problematic aspects exposed during his cross-examination.

248    Further, I have rejected various aspects of the evidence of Ms Herzig. In cross-examination she adopted an argumentative and apparently partisan approach. Further, her evidence was on some occasions contradicted by the contemporaneous documents and the evidence given by other witnesses. In these circumstances, I am cautious about accepting some of the contested aspects of her evidence.

249    Further, I have adopted a cautious approach to aspects of the evidence given by Mr Bembrick, particularly his affidavit evidence concerning the work he undertook whilst employed by Ciba. It became apparent at trial that his affidavit evidence bore significant differences to his oral evidence and that his affidavit had involved reconstruction, undertaken many years after the relevant events had occurred, and in circumstances where Mr Bembrick had reviewed the opposed applications.

250    Further, Dr Clarke was a clever and honest witness. The oral evidence of Dr Clarke was that the secondary dosing process trialled at Yarraman (and subsequently Yoganup) was “a new process that had not been applied at full scale”, that he attended the Yarraman trials to see for himself how the process worked, that he was impressed with the results, and that he considered the trial work to involve new techniques confidential to Iluka and Ciba. As BASF submitted, Dr Clarke had extensive experience in the field such that weight should be placed on his evidence that he had never before his visit to Yarraman observed a process involving secondary dosing of flocculant close to the discharge point at any mine site.

251    Finally, I will discuss aspects of Dr de Kretser’s evidence in a moment.

(b)    BASF’s witnesses

252    Dr John Farrow holds a doctorate in physical chemistry and since 1984 has been employed by the CSIRO.

253    Since 1984, his main research interests have been in surface chemistry and solid-liquid separation in the mining industry, focusing on flocculation, thickener technology and filtration. The primary focus of Dr Farrow’s work was on thickener technology. Dr Farrow had less knowledge in the use of belt press filters or centrifuges.

254    There is a contrast between the backgrounds of Dr Farrow and Dr de Kretser. Dr Farrow had more extensive industry experience and had extensively worked in the field at the priority date. Further, Dr Farrow gave evidence on secondary dosing and common general knowledge which accorded more with the evidence of the fact witnesses than did the evidence of Dr de Kretser. In these circumstances, I have preferred the evidence of Dr Farrow on various aspects that I will discuss later.

255    Mr Stephen Scammell was a sales account manager employed by Ciba in the period from 1991 to 2007. Prior to 1991, Mr Scammell had worked for Catoleum (Nalco) as a sales representative. Mr Scammell was the Ciba sales representative responsible for the CRL account for CRL’s mineral sands mine on North Stradbroke Island in 2002 and 2003. He is one of the named inventors of the claimed invention.

256    Mr Scammell has not been employed by Ciba/BASF for over a decade and is now employed by Sibelco, which was formerly CRL. Mr Scammell gave his evidence carefully and reliably. Mr Scammell made concessions where appropriate and without suggesting that he had a precise recollection of all events occurring years ago. Where there is a conflict between the evidence of Mr Scammell and Ms Herzig, I have accepted his evidence.

257    Mr John Bellwood is Head of Mining Technology Asia Pacific for BASF and has had management roles with Ciba/BASF and its predecessors since 1996.

258    Ms Angela Beveridge is a Senior Technical Specialist with BASF and has performed this role with Ciba/BASF and its predecessors since 1995.

259    Mr Bellwood and Ms Beveridge both gave evidence regarding the Project Zenith / Son of Zenith project, including those aspects of the project they were involved with. Both witnesses were cross-examined regarding the contents of documents they had authored in 2002 to 2003. Their evidence was generally coherent and consistent with other evidence including the contemporaneous documents tendered. They were not cross-examined on large parts of their evidence. I did though consider that some of Ms Beveridge’s evidence was vague and that her memory on occasion was imperfect. I found Mr Bellwood to be an honest, technically skilled and impressive witness although at times overly careful.

260    Mr Martin Edgar is the Regional Sales Manager Asia for BASF. He was only cross-examined briefly.

261    Mr John Lee is a partner at Gilbert & Tobin, BASF’s solicitors. He was not cross-examined.

THE PERSON SKILLED IN THE ART

262    Let me at this point say something about the person skilled in the art.

(a)    Who is the person skilled in the art?

263    Now it is trite to observe that a patent application should be construed through the eyes of the hypothetical person (or team of persons) who is likely to have a practical interest in the subject matter of the claimed invention and may often work in the field of technology to which the claimed invention relates.

264    In the present case, the person skilled in the art is a team of people who had a practical knowledge of, and experience in, the treatment and disposal of mining wastes (including mine tailings) at the priority date including people working for flocculant suppliers, who typically have some tertiary or TAFE qualification in chemistry, consultants who have specialised knowledge and expertise in matters such as rheology and chemistry, and people working for mine operators, who typically have some tertiary or TAFE qualification in chemistry or metallurgy. The relevant field, to use Dr Farrow’s language, was “the art of dealing with tailings in mines”, albeit adopting a description used in the 2008 proceedings. The relevant field was mine tailings disposal which of course included the dewatering of slurries, slimes and tailings generally and as part thereof encompassed tailings beaching and the deposit of tailings.

265    It is apparent from the evidence that flocculant suppliers had important knowledge and experience concerning the treatment and disposal of mining wastes (including mine tailings). Flocculant suppliers would regularly attend mine sites to assist and advise the mine operators on the use of their flocculants including the use in thickeners, belt press filters and centrifuges. Flocculant suppliers regularly attended mine sites to promote the use of their flocculants and undertake trials and tests for that purpose. Further, if a miner encountered an issue which involved the use of flocculants, their first port of call would have been to a flocculant supplier, such as Ciba, Nalco, Cytec or SNF. For example, a decision to add a second dose of flocculant was something that a mine operator might undertake after discussions between the flocculant supplier and the mine processing manager if confronted by a problem in the treatment of its tailings. A mine operator could look to the experience offered by flocculant suppliers to assist in dealing with that problem and the knowledge of in-house metallurgists and chemists employed by flocculant suppliers. Further, when more complex issues were confronted, mine operators could seek assistance from consultants with specialised knowledge and expertise. Those consultants could be sourced from the CSIRO or universities and could include consultants experienced or qualified in a broad range of different disciplines including metallurgists, chemists and chemical engineers.

266    In my view, all of SNF’s witnesses who gave oral evidence were persons skilled in the art at the priority date. All of those witnesses had relevant experience and knowledge of the use of flocculants, flow properties of mine waste/tailings and performance and interpretation of flocculation tests, although some were clearly more experienced than others.

267    Further, BASF’s witnesses were all persons skilled in the art at the priority date.

(b)    Information persons skilled in the art had regard to

268    The accumulated knowledge of the person skilled in the art was derived from a variety of sources which I will briefly summarise at this point.

269    Dr de Kretser said that people working in industry routinely refer to papers, patents, and others industry projects such as the AMIRA 266 project in order to keep abreast of developments in the field. Indeed, it was part of their job description to stay on top of those developments.

270    His experience at Rio Tinto was that there was an extensive internal library of relevant journals which people within that organisation would have referred to. Rio Tinto also had a specific knowledge management practitioner who assisted people in making searches if they needed to find information in relation to a certain task or topic.

271    Dr de Kretser accepted that there was a spectrum of levels of sophistication in terms of searching in the industry depending upon the size and sophistication of the particular operation or operator. He said that any mid-tier miner would necessarily have people in a technology development and deployment role, and that those people would necessarily keep on top of technological developments of interest and relevance to their operations.

272    Further, he said that if a person’s role within the organisation involved technology development and protection of that technology, they would be focused on patent literature. If a company was developing technologies for the mining industry, it would consult patent literature in order to ascertain what its competitors were patenting, so as to understand the focus of their work and to avoid any infringement risk. Whilst working at Rio Tinto, Dr de Kretser regularly observed colleagues with patents on their desk.

273    Further, flocculant suppliers undertook patent searches, both for the purposes of assessing the patentability of their own processes and for freedom to operate.

274    Further, Dr de Kretser’s evidence is supported by Dr Clarke’s evidence regarding the paper presented by Mr Brian Dymond and Mr Don Luke entitled ‘Beyond Conventional Flocculation’ at the High Density & Paste seminar at the Paste and Thickened Tailings conference (the PTT conference) in Pilanesberg, South Africa, on 10 and 11 May 2001 (Dymond paper). Although Dr Clarke did not attend the conference at which the Dymond paper was presented, he became aware of it when he was undertaking research for Iluka in around 2002. I will return to the Dymond paper later.

275    Further, the Paste and Thickened Tailings Guide (PTT Guide) was another source of information to which persons skilled in the art had regard at the priority date; I will return to the PTT Guide later. However, the PTT Guide was one of many available sources of information and was not a complete set of the information available in the field at the priority date. Product technical literature and brochures prepared by flocculant manufacturers were also an important source of information.

276    Further, another source of information which was widely recognised in the water treatment industry was the Nalco Water Handbook. The first edition was published in 1979 and the second edition was published in 1988. Now flocculant suppliers were actively involved in both the water treatment and mineral tailings industries and personnel such as Mr Schroeter and Mr Scammell had experience in both industries. Mr Schroeter said that the Nalco Water Handbook was given to new sales staff when they commenced working at Nalco to use as a reference source. Mr Schroeter said that the Nalco Water Handbook was a widely recognised text within the water treatment industry.

277    Further, the sources of information referred to by a person skilled in the art also included the Minerals Engineering International (MEI) website, which was an aggregation source of information providing summaries of papers and recent advances in technology across all of mineral processing. The MEI website was free to access and an easy place to get a quick overview of work that was done in the field. The MEI website included information concerning mining industry news and developments and recent industry specific publications. Further, The MEI website also included a “new patents” section. Historical pages from that section of the MEI website include extracts of patents relating to the treatment of mineral tailings, including a Ciba patent for a mineral solids separation process in the name of Mr Don Luke, one of the co-presenters of the Dymond paper. Other patents extracted on the MEI website include “apparatus for treating fine ore”, “process for reducing the quantity of water contained in pulps of nickel-bearing oxide ores” and an application filed by Nalco for “Rheology modification of settled solids in mineral processing”.

278    Further, the sources of information referred to by persons skilled in the art included magazines published by industry bodies, promotional information and research updates published by industry bodies and research organisations, and commercial subscription based publications.

279    Let me now turn to questions of construction.

CONSTRUCTION OF THE CLAIMS

280    In MLA (No 1) I set out the relevant principles and it is convenient to repeat what I said at [213] to [220].

281    The principles governing the construction of patent specifications including claims are well established. A claim is construed from the perspective of a person skilled in the relevant art as to how such a person would have understood the patentee to be using the words of the claim in the context of the specification as a whole. Further, a claim is to be construed in the light of the common general knowledge including the art before the priority date.

282    A measure of common sense should be used. And ordinary words should be given their ordinary meaning unless a person skilled in the art would give them a technical meaning or the specification ascribes a special meaning.

283    In terms of how the body of the specification may be used in construing a claim, the claim should be construed in the context of the specification as a whole even if there is no apparent ambiguity in the claim. Nevertheless, it is not legitimate to narrow or expand the boundaries of the monopoly as fixed by the words of a claim by adding to these words glosses drawn from other parts of the specification. More particularly, if a claim is clear and unambiguous, to say that it is to be read in the context of the specification as a whole does not justify it being varied or made obscure by statements found in other parts of the specification.

284    Now the specification may stipulate the problem in the art before the priority date and the objects of the invention that are designed to address or ameliorate this. Accordingly, the specified objects may be useful in construing a claim in context. Nevertheless, the specified objects are not controlling in terms of construing a claim; glosses cannot be drawn from the objects.

285    A claim should be given a purposive construction (Product Management Group Pty Ltd v Blue Gentian LLC (2015) 240 FCR 85 at [39] per Kenny and Beach JJ). Words should be read in their proper context and a too technical or narrow construction should be avoided. Further, the integers of a claim should not be considered individually and in isolation. Further, a construction according to which the invention will work is to be preferred to one in which it may not. But to give a claim a purposive construction “does not involve extending or going beyond the definition of the technical matter for which the patentee seeks protection in the claims” (Sachtler GmbH and Co KG (formerly Sachtler AG) v RE Miller Pty Ltd (2005) 221 ALR 373; [2005] FCA 788 at [42] per Bennett J). To apply a purposive construction does not justify extending the patentee’s monopoly to the ideas disclosed in the specification. I also adopt what was said in Artcraft Urban Group Pty Ltd v Streetworx Pty Ltd (2016) 245 FCR 485 at [72] to [78] per Greenwood J (agreed to by Rares J at [142], [145] and [146]). Further, I would also refer to Lord Hoffmann’s observations in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd (2004) 64 IPR 444; [2004] UKHL 46 at [27] to [34] concerning a purposive approach to construction.

286    As I have said, a claim is to be construed from the perspective of how a person skilled in the art would have understood the patentee to be using the words, informed by the notional skilled addressee’s relevant general knowledge and what has been disclosed in the specification. But to consider such a perspective does not entail that the Court necessarily requires expert evidence to assist on construction. If it is clear that the claims are to be read according to their ordinary meaning with no special meaning given to any word or phrase, if the science or technical issues are easily comprehensible and if, more generally, the Court does not require expert assistance in understanding the context of the claims, then expert evidence on construction may not only be unnecessary, but unhelpful and distracting. The nature and complexity of the patent in suit and the issues raised will determine the utility or necessity for expert evidence on construction. In the present case, I have to some extent been assisted on questions of construction by the expert evidence adduced by the parties, but the significance and weight of such evidence should not be over-stated. After all, the proper construction of a claim is ultimately a question of law for me, albeit that I must adopt the perspective that I have just described.

287    In terms of the skilled addressee, one is using a hypothetical construct. The following principles are applicable:

(a)    First, to identify the characteristics of the skilled addressee, the field to which the invention relates must be identified.

(b)    Second, the skilled addressee is taken to be a person of ordinary skill (as opposed to a leading expert) in that field and equipped with the relevant common general knowledge including the art before the priority date.

(c)    Third, the qualifications and experience of the skilled addressee will depend on the particular case, having regard to the nature of the invention and the relevant industry. Formal qualifications are not essential. Practical skill and experience in the field may suffice. A patent specification is addressed to those having a practical interest in the subject matter of the invention; such persons are those with practical knowledge and experience of the kind of work in which the invention is intended to be used.

(d)    Fourth, the hypothetical person skilled in the art may possess an amalgam of attributes drawn from a team of persons whose combined skills, even if disparate, would normally be employed in interpreting and carrying into effect instructions such as those contained in the specification.

(e)    Fifth, as the skilled addressee comes to a reading of the specification with the common general knowledge of persons skilled in the relevant art, they read it knowing that its purpose is to describe and demarcate an invention. But the person skilled in the art is not particularly imaginative or inventive.

(f)    Sixth, the skilled addressee does not come to reading the specification seeking failure.

288    As I have said, the legal construct may not be a single person but may be a team of persons whose combined skills would normally be employed in that art in interpreting and carrying into effect instructions such as those contained in the relevant instrument.

289    In the appeals before me the language of the claims which falls to be determined in the present case is as follows:

(a)    “rigidify”, “rigidification” and “improving rigidification”;

(b)    an “effective rigidifying amount”; and

(c)    “co-disposal”.

290    Otherwise, the meanings of the following terms and expressions in the opposed applications do not appear to be in doubt.

291    First, “tailings” or “tails” refers to waste material produced during the process of extracting minerals from mined material. They are the end product of a mineral processing operation.

292    Second, the reference to bimodal distribution of particle sizes refers to tailings having a particle size distribution with two characteristic populous sizes.

293    Third, the reference to bimodal distribution of particle sizes comprising a fine fraction and a coarse fraction refers to the material having two characteristic populous sizes of particles, one being fine and one being coarse, in which the:

(a)    coarse particles have a size distribution peak (most common size) of greater than 75 microns,

(b)    fine particles have a size distribution peak (most common size) of less than 25 microns.

294    Fourth, a “coarse solid” is a particle greater than 75 microns and up to 10,000 microns. A “fine solid” is a particle smaller than 25 microns.

295    Fifth, the expression “during transfer” refers to the transfer of thickener underflow between the thickener and the deposition area.

296    Sixth, as I have already touched on, the expression “intrinsic viscosity” refers to a physical property of an aqueous flocculant solution which can be used to quantify the molecular weight of the dissolved flocculant species (size/length of the flocculant chain). The higher the molecular weight, the higher the intrinsic viscosity.

297    Seventh, the reference to wet or dry coarse particles being added to the underflow refers to coarse particles being added to a thickener underflow stream as:

(a)    a slurry comprised of coarse particles and water;

(b)    de-watered solids, such as the discharge from a vibrating dewatering screen; or

(c)    dry material;

and then mixed with the thickener underflow by some means appropriate to the specific application.

298    Eighth, the term “homogenous mixture” refers to a mixture where coarse and fine particles are evenly dispersed with no appreciable segregation. Relatedly, the reference to co-disposal of coarse and fine solids as a homogenous mixture refers to a co-disposal process by which the coarse and fine particles are disposed together such that no appreciable segregation is evident in the finally deposited material, although I would note that the opposed applications do not exclude the possibility of some segregation on deposition.

299    Ninth, the term “heaped geometry” refers to a beach with a relatively steep beach angle, with the material having a sufficient slope such that the rate of drainage from the deposited material prevents the build-up of free water over the top of the deposited material.

300    Let me now discuss in more detail the construction of the relevant terms and expressions which were the subject of more detailed focus before me.

(a)    Rigidification and improving rigidification

301    Now “rigidify” and “rigidification” are ordinary English words. “Rigidify” means “[t]o become rigid, set, or inflexible”; and “rigid” means, in relation to material, “stiff; not pliant or flexible; firm; hard” (Oxford English Dictionary (2nd ed, 1989)). The noun “rigidification” has a cognate meaning. No one doubted that in terms of the construction of the relevant claims these meanings should be applied.

302    Now I am prepared to accept that:

(a)    the underflow from a conventional thickener was material that had been rigidified;

(b)    the discharge from a paste thickener was material that had been rigidified;

(c)    the material which is discharged from a belt press filter is rigidified;

(d)    a specific measure of rigidification is the yield strength of the material which could be quantified and measured; and

(e)    stacking angle is an indicium of rigidification, with steeper stacking angles being consistent with extra structure having been introduced into that material.

303    I am further prepared to accept that persons skilled in the art:

(a)    were familiar with the concept of rigidifying tailings material that was subsequently deposited in a deposition area;

(b)    were familiar with using flocculant to treat tailings material to rigidify that material in thickeners, belt presses and centrifuges;

(c)    knew there were different degrees of rigidification;

(d)    were accustomed to examining the rigidification of material that had been treated with flocculant, and forming a view as to whether, after treatment, the rigidification of the material had improved; and

(e)    could conduct routine tests to determine if the material that had been treated with flocculant had achieved an improvement in rigidification and could improve the rigidification of the material being treated if desired.

304    In terms of “rigidification” I largely accept the evidence of Dr de Kretser.

305    The meaning of the term “rigidification” refers to the process of changing an initially fluid mixture of solid particles and liquid into one where the solid particles are held within a networked deposit with some level of mechanical strength by the following processes:

(a)    First, flocculation at some point prior to deposition, such that large and strong flocs are formed. Depending on the system, operating conditions and flocculant dosages, these flocs could range from centimetres in size up to an interconnected mass of order of the size of the outlet pipe.

(b)    Second, at the point of deposition, the permeability of the slurry at its transfer solids concentration is significantly increased as a result of the well-developed, almost granular floc structure. This means that the flocs settle/separate rapidly from the slurry stream as it slows on exit from the discharge point.

(c)    Third, the rapid settling/separation leads to release of a significant amount of free water and a corresponding solids concentration increase. As a result of both the solids concentration increase and the strength of the flocs themselves, the yield stress of the material increases to the point where the solids cease moving and form a well developed beach, with a relatively steep beach angle. Due to the over-flocculated structure, inter-floc water can almost freely drain down the beach governed by the increased permeability. But initially the over-flocculated material will have an open, porous, and relatively low-density, compressible structure.

(d)    Fourth, due to the rapid deposition of the flocs from slurry, material accumulates more rapidly over previously deposited solids. Thus compressive dewatering of the initially low-density flocs is promoted resulting in expression of water from the beach with a further increase in the solids concentration of deposited solids. The compressive dewatering would typically be at an enhanced rate due to the enhanced permeability.

306    The process of “rigidification” involves exploitation of increased permeability via settling/separation, drainage and consolidation rate to more rapidly reach a solids concentration exhibiting a desired level of mechanical strength. Additionally, the high flocculant dosage results in increased inter-particle forces meaning this strength is achieved at a lower solids concentration, requiring less water removal for its development.

307    I also agree that successful implementation of rigidification would result in the following behaviour after discharge of slurry into a deposition area:

(a)    Rapid attainment of a solids concentration at which the mechanical strength of the inter-particle network results in accumulation of a deposit with solid-like properties. Such a deposit has a strength sufficient to resist re-mobilisation by subsequently deposited material.

(b)    This solids concentration would be typically achieved through rapid settling and separation of clarified water immediately after deposition.

(c)    Formation of a relatively steep beach of deposited solids as a result of the processes in (a).

(d)    Retention of coarse particles present in the initial slurry within the flocculated fine particle matrix such that segregation within the deposited material is prevented.

308    Let me now turn to the more difficult question of the construction of the expression “improving rigidification”. The claims of the opposed applications are directed to a process of “improving rigidification”. But it is apparent from the opposed applications and the evidence that improving rigidification is a qualitative and relative concept.

309    The description of the process of “improving rigidification” appears in the body of the specifications of the opposed applications. What is taught is that:

(a)    the treated material is to stand and rigidify and therefore forming a stack of rigidified material;

(b)    the formation of stacks has the advantage that less area is required for disposal;

(c)    the rheological characteristics of the material are important since once the material is allowed to stand it is important that flow is minimised and that solidification of the material proceeds rapidly;

(d)    the rigidified material must be sufficiently strong to remain intact and withstand the weight of subsequent layers of rigidified material;

(e)    the process will preferably achieve a heaped disposal geometry and will co-immobilise the fine and course fractions of the solids and will allow released water to have a higher driving force to separate it from the material by virtue of hydraulic gravity drainage;

(f)    the heaped geometry will give a higher downward compaction pressure on underlying solids which seems to be responsible for enhancing the rate of dewatering;

(g)    as a result, the process will achieve a higher volume of waste per surface area;

(h)    it is not possible to achieve the objectives by adapting the flocculation step in the thickener and that it is essential to treat the material that has been formed as an underflow in the thickener; and

(i)    it is important that the liquor released as part of this process is clear and substantially free of contaminants, especially migrating particulate fines.

310    Further, to achieve improved rigidification, the opposed applications teach that the material must be treated with “[a] suitable and effective rigidifying amount of the water-soluble polymer solution”, at an effective point. The examples in the opposed applications then provide slump test results for a range of doses of various polymers in various forms on a variety of slurries as follows: mineral sands – tables 3 and 18; lateritic nickel, acid leach process – table 9; red mud – table 11; gold processing – table 13; lead/zinc – table 15; and coal – table 17.

311    The examples in the opposed applications are important in giving meaning to the phrase “improving rigidification” and how it is to be achieved.

312    By way of illustration, Example 12 in the opposed applications teaches that in a plant evaluation at a mineral sands process, where dosages of 100g/t of dry solids were used at a dosing point 20 metres (11 seconds) prior to discharge, the process achieved: (a) stacking angles of 8 – 10 degrees; (b) “clean water release”; and (c) “a retention of the fine material within the heap disposal”. Figure 6 then provides a visual illustration of material treated with the claimed process. This plant evaluation was undertaken following the laboratory results reported in table 19, which records different slump results achieved at different mixing times and different dose rates.

313    Similarly, table 20 in the opposed applications teaches, when read in the context of the opposed applications in their entirety but particularly page 15 of the opposed applications, that the process seeks to achieve “a significantly high-yield-stress material… so that when it discharges, it stands and does not move very far from the discharge point”. For example, table 20 teaches that a dose rate of 160 g/t and 10 seconds mixing time increased the yield stress of the material from 65 to 356 Pa. This teaches that yield stress increases significantly and that the treated material is to have the type of yield stress that would come from paste thickener and have all the beneficial properties of a paste-thickened material.

314    So in summary, the specifications of the opposed applications including the examples, tables and figures give meaning to the phrase “improving rigidification”.

315    Now Dr Farrow identified six qualitative characteristics of improved rigidification. The treated tailings would:

(a)    be less likely to spread laterally after deposition, enabling more efficient land use;

(b)    more rapidly form a solid structure in the form of a beach or stack;

(c)    have a greater yield stress when deposited;

(d)    have an increased uniformity or homogeneity of fine and coarse particles;

(e)    have a heaped geometry which would result in downward compression forces in the deposited material, forcing water out of the stack; and

(f)    have more rapid and improved clarity of water release in the disposal area.

316    In his evidence Dr Farrow accepted that the comparator using these indicia was thickener underflow which had not been treated with a second dose of flocculant (untreated tailings). That is, the “improvement” in rigidification required by the claims is to be assessed by comparing the rigidity of the deposited material, which has been treated with a second dose of flocculant, with the rigidity of material which has only been treated with flocculant in the thickener. I agree.

317    But as a matter of plain language, it follows that any improvement on the results achieved by depositing untreated tailings, even if small, would constitute improving rigidification.

318    Now Dr Farrow accepted in cross-examination that feed material which has been flocculated downstream of a conventional thickener and placed on a belt press filter is material that exhibits “improved rigidification”.

319    In his evidence, Dr Farrow explained his understanding of the process of “improving rigidification” as described and claimed in the opposed applications to the effect that:

(a)    it is a qualitative term not defined in the opposed applications in a quantitative way;

(b)    rigidification is caused in the pipe through the addition of flocculant to the tailings in the pipe;

(c)    when the material is discharged, all the material will stand at the discharge point forming a beach;

(d)    depending on the yield stress, the deposited material will only be pushed forward when extra deposited material provides enough force to exceed the yield strength of the deposited material;

(e)    there will be some flow of the deposited tailings depending on the level of yield stress in the material, but an important feature of the claimed invention is that the flow of material is minimised;

(f)    the extent to which the material flows on deposition will depend upon the amount of flocculant that is added and where it is added;

(g)    as the water leaves the deposited tailings, the solids concentration will increase;

(h)    there will be a rapid rise in the yield strength as the water is released and the material will be further rigidified or solidified; and

(i)    the steeper beach angles formed by the deposited material will increase the volume of tailings which can be stored in a given surface area.

320    Now Dr de Kretser’s understanding of the qualitative indicators of improved rigidification was largely consistent with that of Dr Farrow. In this respect he identified the following qualitative indicators of “improved rigidification”:

(a)    the tailings have been strongly flocculated such that large flocs of solids are present after deposition; he said that the large flocs possess an interconnected network between the particles such that the material has an integral strength which can withstand application of an external force (a yield stress);

(b)    the tailings have greatly enhanced permeability, reducing the time taken to dewater to the point where a beach develops;

(c)    the tailings achieve sufficient yield stress to promote beach development at a lower solids concentration than untreated tailings;

(d)    the tailings exhibit improved water release and recovery after deposition when compared with untreated tailings;

(e)    the tailings occupy a smaller surface area than untreated tailings; and

(f)    the tailings are more quickly rehabilitated than untreated tailings.

321    Dr Farrow agreed that improved rigidification results in the rapid formation of a solid structure in the form of a beach or stack. And Dr de Kretser accepted that the speed of creation of a stable deposit was relevant in determining whether there was an improvement in rigidification, but the actual time taken to achieve a stable deposit depended on the type of material that was being treated. For him, for certain types of material such as phosphate tailings, obtaining a stable deposit within weeks would be considered to be rapid. I am not sure that I completely agree with that characterisation.

322    Let me turn to the aspect of network structure and chemical bonding.

323    As I have indicated earlier in my reasons, flocculants cause solids in a slurry to aggregate into flocs that under certain conditions will start to stick together to form a structure that is permeable and allows for further dewatering. This causes an increase in the yield stress of the material.

324    Once the flocculant is added, the solid particles in the slurry attach to the flocculant forming aggregates, and the liquid between these growing solid aggregates carries them to the deposition area. The treated material is then deposited in the deposition area.

325    When particles or aggregates (flocs) are in close physical proximity there is an opportunity for flocculant bridging between the particles or aggregates. If there is exposed flocculant on the outside of an aggregate, there is an opportunity for flocs to then attach to neighbouring aggregates. This mechanism provides an opportunity for additional bonding to take place.

326    Now there was a dispute between the experts concerned the precise nature of the underlying chemical-physical nature of the deposited material that arises when improved rigidification is achieved. More particularly, the dispute between the Dr de Kretser and Dr Farrow was whether there were molecular bonds between individual flocs when improved rigidification is achieved.

327    Dr Farrow’s evidence was that in order to achieve “improved rigidification” a sufficiently high solids concentration was required to enable particles to be in sufficiently close proximity so that when a sufficient dose of flocculant was added those particles joined together and formed a single unified network structure. Dr Farrow’s evidence was that it would be feasible to achieve improved rigidification if the solids content was in a range of 15 to 80%.

328    His evidence in relation to the nature of the structure or bond created when improved rigidification is achieved was to the following effect. A flocculant induces aggregation of the solid mineral particles by the flocculant molecules co-adsorbing on two or more solid particles and binding them together through a molecular bond. Adsorption refers to the adhesion of the flocculants onto the surface of the solid particles in the tailings. This can be either physical or chemical and the specific nature of chemical bonding can vary. And in addition to the molecular bonds between the particles, there are also molecular bonds between individual flocs when improved rigidification is achieved.

329    Contrastingly, Dr de Kretser did not accept that when improved rigidification is achieved, there are molecular bonds formed between individual flocs. Dr de Kretser’s evidence was that the process of the claimed invention does not require that the treated material as deposited is fully interconnected in a chemically bonded sense. Dr de Kretser’s evidence was that after a sufficient dose of flocculant has been added to thickener underflow an interconnected network of large flocs will form. Those large flocs will consist of particles that have been molecularly bonded together to form the larger floc. But the large flocs may not themselves be bonded to other flocs.

330    Let me elaborate a little further on networking.

331    Neither of the opposed applications explicitly refers to “networking”. Nevertheless, the concept of networking is important in understanding how improved rigidification, as taught and claimed in the opposed applications, is achieved. Both Dr Farrow and Dr de Kretser agreed that networking was required to improve rigidification. But at trial, it became apparent that the extent of their disagreement was limited to the degree of networking required and the precise bonding mechanism for and explaining the networking.

332    The evidence of Dr Farrow was that the process claimed in the opposed applications requires the flocculant “to bridge all the particles together to form a network, not just form a multitude of individual aggregates”. Dr Farrow explained that this is a “dynamic process where small “sub networks” will initially form and then in the presence of the remaining flocculant these smaller “sub-networks” will progressively join to form an overall network”. The overall network is the result of “the flocculant forming molecular bonds between all of the particles i.e. the structure does not consist of a collection of discrete aggregates”.

333    Dr Farrow explained that this networked structure “has very different properties and characteristics, including in relation to dewatering, compared to a conventional settled deposit of a dry stacked deposit” and is the reason why “a rigidified deposit formed by the process described in the opposed applications has the characteristics” of improved rigidification, namely:

(a)    it is less likely to spread laterally after deposition enabling more efficient land use;

(b)    it will more rapidly form a solid structure in the form of a beach or stack;

(c)    it will have a greater yield stress when deposited;

(d)    it will have an increased uniformity or homogeneity of fine and coarse particles;

(e)    the heaped geometry results in downward compression forces in the deposited material forcing water out of the stack; and

(f)    more rapid and improved clarity of water released in the disposal area.

334    The evidence of Dr de Kretser on improved rigidification accorded in many material respects with the evidence of Dr Farrow. Dr de Kretser gave evidence that improved rigidification as claimed in the opposed applications would be achieved where the tailings had been “strongly flocculated such that large flocs of solids are present” and that the “large flocs possess an interconnected network between the particles such that the material has an integral strength which can withstand application of an external force (a yield stress)”.

335    Dr de Kretser gave evidence that “rigidification” requires that “extremely large and strong flocs are formed” and that, depending on the system, “these flocs could range from centimetres in size up to an interconnected mass of order of the size of the outlet pipe”. Dr de Kretser further explained that “improved rigidification” requires the building of “a more extensive, stronger flocculated network”.

336    As I say, there was really only one substantive point of disagreement, namely, the extent and nature of the networking required. Whereas Dr Farrow considered that in order for improved rigidification to be achieved the deposited material needed to form part of an overall network created by molecular bonds, Dr de Kretser asserted that improved rigidification could be achieved in a tailings slurry consisting of a series of discrete aggregates each constituting its own molecularly bonded network, which became “networked” as a result of an increasing solids concentration.

337    In his affidavit, Dr de Kretser set out a schematic illustrating “the range of solids concentrations and inter-particle structures”. The schematic, which I have set out earlier, is again set out for convenience:

338    Focusing on the teachings of the opposed applications, Dr de Kretser gave the following evidence when cross-examined, in respect of the top right stage of the schematic:

Mr Caine, in opening at transcript 85, line 16, suggested that those dotted lines were molecular bonds; you would accept that - - -?---They – they could - - -

- - - in the process described in the patent that’s what’s contemplated?---That is what is contemplated.

339    But he later clarified in the context of improved rigidification:

HIS HONOUR: Can I just ask you, the reference in 176 to inter-particle forces; are you referring there to the network of flocs that you had in your earlier diagram?---Yes. I mean - - -

Yes?---In the context of talking about a high flocculant dosage resulting in increased inter-particle forces, I am talking about the molecular bonds between them.

The polymer and the - - -?---Yes. And – so the rigidity of the flocs themselves.

Yes. Thank you. Rather than the diagram that you’ve got of a network of flocs it might - - -?---Yes. Yes.

Have physical forces that keep them together?---Because – well, I guess, ultimately, irrespective of the dotted lines, which I’ve drawn in that diagram which we could say are not necessarily molecular bonds, the underlying – as material deposits into a sediment, the overall strength of that sediment is largely governed by the molecular bonds within the flocs that formed that sediment.

340    Further, the evidence of Dr de Kretser was that for “extremely large flocculated masses”, the second stage of dewatering is “effectively instantaneous”, and that “time is important” when assessing improved rigidification and the opposed applications are concerned with rapid beaching and rapid separation of clarified water.

341    Nevertheless, Dr de Kretser maintained that there was no requirement for an overall networked structure to achieve improved rigidification because “you will see that my evidence in relation to the patented process suggests that it – that they’re exemplars of the patented process in which discrete aggregates are being deposited and in no way can be inferred as an extensive completely network[ed] material where all of the particles are connected together”.

342    In other words, the evidence of Dr de Kretser was that an overall networked structure was not required to improve rigidification because this was not present in some of the exemplars.

343    Further, when Dr de Kretser was cross-examined on his evidence concerning networking, he ultimately agreed that what was required was the formation of “large flocs” from smaller flocs:

What you’re suggesting, if I’ve understood it correctly – and let me replay it to see that I’m not misrepresenting what you’re saying. In the process of adding a significant dose of flocculant close to the discharge point in the tailings pipe, you have a process where particles are bonded with the molecular bonds to form a floc. Some of those flocs will form together to form larger flocs?---Yes.

What you’re saying is that, ultimately, there might be a number of the large agglomerated flocs, but they won’t necessarily themselves be bonded?---Between them, yes.

Yes?---Yes.

344    In my view, there is little substantive difference that I need concern myself with between the evidence of Dr Farrow and Dr de Kretser on networking. Both agree that flocculants work by creating molecular bonds between particles and both agree that to achieve improved rigidification, sufficient flocculant must be added so that “small flocs” or “discrete aggregates” or “sub networks” are in some sense “bonded” together to form “large flocs” or an “overall network”. So much was subsequently affirmed by Dr de Kretser during his cross-examination:

So you have a sufficient dose of flocculant so that large flocs of solids are present, an[d] the large flocs can either be a whole pile of particulate matter all bound together or groups of those smaller aggregates that have been bonded together to form a large floc?---Yes.

And the effect of that is that ... those large flocs possess an interconnected network between the particles. And when you say an interconnected network between the particles, that encompasses, also, the smaller aggregates that might be within that large floc?---Yes. It encompasses the physical interactions between flocs as well as any chemical interactions.

Yes. And there might be both?---Yes.

Yes. And such that the large flocs has an integral strength which can withstand an application of yield stress?---Yes.

And the consequence is that when you have these large flocs discharged you get what you’ve described in paragraph 177?---Yes.

345    Further, Dr de Kretser affirmed that the process claimed in the opposed applications “will generally develop a strong network and, potentially, a more extensive network” and that when he was talking about an “extensive network” this included “individual aggregates of particles themselves flocculated in a network being joined with other aggregates to form a larger floc”. Dr de Kretser also clarified that he did not wish to draw any distinction between a network of particulates bound by flocculants and a network between flocs:

MR SHAVIN: Now, can I break that down a little bit: there’s no dispute between you and Dr Farrow that in the context that we’ve discussed there are molecular bonds in the network?---Within a floc, yes.

Yes. And there’s no distinction – there’s no disagreement, is there, that when one is looking at what comes out of the thickener, we’re looking at the relative size, structure and extent of the network?---When you’re saying – comparing that to the patented process?

Yes?---The patented process, because of the conditions under which polymer is added and the generally higher dosage required to obtain a flocculated network will generally develop a stronger network and, potentially, a more expensive network depending largely on the conditions within the deposition area and the share conditions.

Yes. And by - - -?---But in all cases – they are molecularly bonded networks in both cases – in thickener underflow, and secondary flocculated thickener underflow.

Yes. And when you talk about an extended network, this includes but is not limited to individual aggregates of particles themselves flocculated in a network being joined with other aggregates to form a larger floc?---Yes.

Yes.

HIS HONOUR: Although, I just want to be clear about that. Your last sentence says “within a floc, a molecularly bonded network”, and counsel is now putting to you a different type of network, which is a network of flocs. Not a network of particulates bound by flocs. So there seem to be two concepts of network here. So in relation to not a network of particulates bound by flocculant, which produces a floc – but let’s talk about a network between flocs. What’s your evidence?---I prefer to, again, make no distinctions between a network formed of flocs of flocs, and simply just consider that it’s the extent of the network because, as I’ve said, in feed to a thickener, it is completely – it – the feedwell of a thickener is also designed to create flocs of flocs, so I cannot make a distinction between – on that basis between thickener underflow and secondary treated .....

There is one distinction, though, isn’t there? The thickener is normally physically proximate to the processing plant?---Yes.

The discharge point – the TSF I think it has been referred to by - - -?---Yes.

- - - in the literature, is often not physically proximate to the thickener?---That’s correct.

346    Moreover, Dr de Kretser accepted that the process claimed in the opposed applications would require flocs that are “stronger and potentially more extensive in size”, that a “consequence” of the process would be “large flocs”, and that flocs would “be allowed to grow to a higher size, larger size”. Dr de Kretser explained, in this respect, that “if a sufficiently high dosage of flocculant is added, a gelatinous blob…might just come straight out of the pipe and deposit with no movement”. That, of course, accords with the teaching in the opposed applications that “once the [deposited] material is allowed to stand it is important the flow is minimised”.

347    What is the effect of all this evidence? In my view, it establishes that whether the treated material is characterised as forming part of an “overall network” (as Dr Farrow prefers) or “large” and “strong” flocs which are themselves networks of smaller flocs (as Dr de Kretser prefers), the end result is the same.

348    Now SNF submits that the precise chemical and/or physical structure of the treated material deposited is not relevant to the construction of “improved rigidification” as such. Ultimately the way in which the structure of the deposited material is formed is largely irrelevant. What is important is that the deposited material has the requisite strength and permeability to exhibit improved rigidification on deposition. I tend to agree. In my view the person skilled in the art would not understand the terms “rigidification” or “improved rigidification” by reference to the underlying physical or chemical structure of the deposited material, but rather by reference to its qualitative characteristics which are visually discernible. Persons skilled in the art are unlikely to care about the details of the type of bond, just that each flocculant molecule adsorbs strongly two or more particles and binds them together. The assessment of the rigidified nature of deposited material is made through visual observation of the nature of the deposited material rather than any consideration of the underlying chemical or physical forces present in the material. In my view, persons skilled in the art were concerned with the functional outcome of the deposition strategy such as the formation of a beach which promotes drainage, stability and an increased rate of rehabilitation. Indeed, the person skilled in the art had no ready way of determining whether deposited material consisted of physical or molecular bonds within the flocs or between the flocs.

349    Let me elaborate further on the functionality of material standing until it is pushed forward by other material. Dr Farrow’s evidence was that a further feature of improved rigidification is that the material stands until it is pushed forward by other material. But Dr Farrow also accepted that there must be some flow of the deposited tailings. The deposited tailings must spread out in order to make efficient use of the impoundment space. But in any event the underlying mechanism for the formation of the deposited material, including the precise manner in which the material spreads, is not directly relevant to the assessment of the validity of the claimed invention. The assessment of the extent and nature of rigidification is to be made by reference to relevant qualitative indicators.

350    Let me also deal with the concept of improved rigidification as distinct from settling/sedimentation.

351    Dr Farrow sought to distinguish some prior art relied on by SNF on the basis that it disclosed “settling” or “sedimentation” as opposed to “improved rigidification” because:

(a)    the prior art used the word “settle”;

(b)    the process involved sub aqueous deposition; and/or

(c)    the process involved the use of containment walls or engineered structures.

352    But SNF says that Dr Farrow adopted a varying and inconsistent approach to his assessment of the prior art, which allowed for prior art to be “conveniently and semantically distinguished”. For example, Dr Farrow sought to distinguish the Backer & Busch 1981 paper by referring to disclosures of “immediate separation of water and solids” and “the flocculated solids readily settled and relatively clear water was liberated” as “exactly what would be expected from a flocculation/settling process”. But SNF says that the observations in the Baker & Busch 1981 paper are precisely those identified in the opposed applications as being the desired result of rigidification. Similarly, SNF says that Dr Farrow distinguished prior art as not disclosing rigidification merely because of references to the “settling” of the flocs or use of the word “sedimentation”. But SNF says that this is notwithstanding that the 785 application on page 16 lines 20 to 26 refers to the claimed invention involving the transfer of treated material to a “settling area” where the material is allowed to dewater to release liquor. Further, SNF says that Dr Farrow attempted to distinguish prior art on the basis that the material is deposited into a dam or other containment area and therefore cannot have achieved “improved rigidification”.

353    Now in my view there is a conceptual distinction between “improved rigidification” and the concepts of “settling” or “sedimentation” and I will come back later to discuss the s 7(3) prior art. But I do agree with SNF that “settling” or “sedimentation” concepts are not foreign to and may be part of the process(es) of the claimed invention.

354    First, the 785 application itself provides for the deposition of material into a “tailings dam or a lagoon”. The final paragraph of page 16 of the 785 application states:

In this form of the invention the aqueous polymer solution is applied to the material in a similar manner as described above. In this case, the polymer solution is applied in an effective dewatering amount and in the same way as a first aspect of the invention it is important that the fluidity of the material is retained during transfer. The material is transferred to a settling area, which can for instance be a tailings dam or a lagoon.

(Emphasis added.)

355    Second, in example 13 on page 38 of the 785 application it is noted that in this working of the claimed invention, the material was discharged into a series of pits that were filled sequentially.

356    Third, in evidence before me was a brochure produced by Ciba which refers to Ciba’s Rheomax ETD program. Rheomax ETD is the trade name for Ciba’s flocculants used in relation to the claimed invention and other applications. Pages 4 and 5 show a working of the claimed invention where the tailings are deposited into impoundment cells.

357    In my view, there is no reason why rigidification of material cannot also occur if the material is deposited into a dam, pond or lagoon. Under such circumstances, the deposited tailings could first settle with development of a sedimentary delta, but would eventually accumulate and form a beach above the water level. The material in such a beach would be subject to hydraulic gravity drainage.

358    Finally on the topics of “rigidification” and “improving rigidification”, let me deal with some other matters.

359    First, it is important to note that the opposed applications do not claim to have invented “rigidification” of tailings. The claims are concerned with “[a] process of improving rigidification of a material...”. Thus, the opposed applications are teaching and claiming “a process” which improves upon rigidification previously known.

360    Second, the meanings of “rigidification” and “improving rigidification” were debated at length in the 2008 proceedings before Kenny J who held that they were not terms of art (SNF (Australia) Pty Ltd v Ciba Speciality Chemicals Water Treatments Ltd (2011) 92 IPR 46 at [47]). Her Honour had regard to the competing evidence of the experts in the 2008 proceedings and ultimately adopted the evidence of BASF’s expert, Dr Farrow, as to meaning (at [69] to [75]). Her Honour then said at [267], which was upheld on appeal (SNF (Australia) Pty Ltd v Ciba Speciality Chemicals Water Treatments Ltd (2012) 204 FCR 325):

I accept Dr Farrow’s evidence that “rigidification” is a qualitative term, although one that Patent 944 explains clearly as “a networked structure”. Further, for the reasons already stated, I conclude that Dr Farrow’s evidence supports the Ciba respondents’ basic contention that, read within the context of Patent 944 (and the other patents in suit), compared with settling and sedimentation processes, rigidification is faster; produces more recovered water; and results in chemically-bonded tailings that occupy a smaller surface area, which are more quickly rehabilitated. I also accept that, as Dr Farrow said, rigidified tailings material would be less likely to spread laterally after deposition, enabling more efficient land use; and would more rapidly form a solid structure in the form of a beach or stack; and have a greater yield stress when deposited, with increased uniformity or homogeneity of fine and coarse particles. Further, by reason of its heaped geometry as a beach or stack, such rigidified material would result in downward compression forces driving water out of the stack and more rapid release of water, with better clarity.

361    Mr David Shavin QC for BASF submits that I should adopt the same construction in these appeals by simply following her Honour’s conclusions. Now it has been held that as a matter of judicial comity an earlier decision on the construction of a patent should usually be followed (see Neurizon Pty Ltd v Jupiters Ltd (2004) 62 IPR 569 at [32] and [35] per Kiefel J). But in the present case of course I am not dealing with the innovation patents dealt with by Kenny J and so have discussed and decided the matter for myself.

(b)    Effective rigidifying amount

362    The opposed applications refer to suitable doses ranging from 10 to 10,000 g/t of material solids, and preferred doses in the range of 30 to 3,000 g/t, with more preferred doses ranging from 60 to 200 or 400 g/t.

363    The opposed applications disclose that SDITB had been used to treat thickener underflow to improve the compaction of the fine waste material and clarity of the recovered water applying flocculants at “conventional doses”, but that this had produced little benefit.

364    It is well apparent that the opposed applications disclose that when flocculant had been added at conventional doses, the following problems described in the opposed applications had not been solved:

(a)    the coarse and fine particles were not being deposited together in a homogenous deposit;

(b)    consequently, the coarse material settled much faster than the fine material, causing banding or segregation; and

(c)    the run off water contained high proportions of fine particles that contaminated the recovered water.

365    There is little doubt that as at the priority date, a person skilled in the art would understand what conventional doses of flocculant would be required for specific purposes and would know that conventional dosages would vary depending on the type of tailings and how the tailings were to be treated.

(c)    Co-disposal

366    As I have already said, tailings are often produced in two size fractions: a coarse fraction and a fine fraction. The coarse tailings are made up of sand sized particles. Fine tailings or slimes are generally made up of silt or clay-size particles. For example, in mineral sands mining, two streams of waste material are typically produced, one being predominantly fine particles and one being predominantly coarse particles.

367    Now the coarse and fine particles in the tailings may have originally been part of the same tailings stream but may have been recombined after a prior upstream separation step. Alternatively there may have been tailings streams generated from different parts of the process employed at a mine. Alternatively, the coarse particles may have been sourced from elsewhere on site such as sources of waste rock or off site such as sand, and then added to the fine tailings stream.

368    It is not in doubt and both of the experts accept that “co-disposal”, as that term was used in the opposed applications, was the deliberate combining of a separate stream of coarse material to the thickener underflow.

369    In my view, the use of the term “co-disposal” in the opposed applications would be understood by a person skilled in the art at the priority date as referring to a process whereby there is a step of combining coarse and fine process streams to create a combined co-disposal stream.

370    I should also say for completeness at this point that a number of the claims of the opposed applications contain specific requirements as to when in the process of improving rigidification the co-disposal step is to occur. For example, claim 17 of the 785 application explicitly requires that the “wet or dry coarse particles are added to the underflow…before or during the addition of an effective rigidifying amount of the water soluble polymer”. Claim 1 of the 568 application explicitly requires that:

(a)    aqueous suspensions of fine and coarse particulates be combined for the purpose of co-disposal to form a material;

(b)    the aqueous suspensions be mixed into a homogenous slurry; and

(c)    during or after mixing of the aqueous suspensions, an effective rigidifying amount of an aqueous solution of a water-soluble polymer be combined.

371    The opposed applications also teach that the effective rigidifying amount of the water-soluble polymer solution will normally be added during or after the mixing of the different waste streams into a homogenous slurry.

372    I need not say anything further at the moment on this aspect.

COMMON GENERAL KNOWLEDGE

373    I have already dealt with matters of common general knowledge that are essentially not in dispute earlier in my reasons. Let me now elaborate and address some additional matters and also turn to more contentious areas.

(a)    Tailings beaching

374    First, let me deal with yield strength in the context of tailings beaching. In the context of tailings beaching the following was well known at the priority date. Mine operators could produce thickener underflow with a very high yield strength which would assist in tailings beaching. But often thickener underflow had to be pumped long distances to a deposition area. However, shear forces in the pipeline would cause the yield strength of the slurry to break down as it was pumped to the deposition area. The effect of shear degradation during transit was that the deposited material would have reduced yield strength (viscosity) and permeability and compressive strength. This would adversely affect the ability to obtain a stable deposit and clear water run-off. Now a person skilled in the art knew that flocculation in the thickener could be used to increase the yield stress of the material being deposited. But if the thickener underflow had a high yield strength, this would put strain on pumps and cost more in terms of power than a less viscous underflow. Additionally, if the yield strength of the tailings within the thickener was too high, the rakes in the thickener could be damaged. Therefore, there was a trade-off between obtaining a higher yield strength underflow to assist in tailings beaching, and having a less viscous underflow which was easier and less expensive to pump.