Field of the Invention

The present invention concerns a process of heap leaching metal from a metal bearing ore in which the ore is agglomerated using an agglomeration agent thus forming an agglomerated ore which is formed into a heap. A leaching solution is then percolated through the agglomerated ore which extracts the metal for subsequent recovery. The solution containing the leaching solution with the extracted metal is often referred to as a pregnant leaching solution. In the present invention the agglomeration agent comprises a hydrophobically associating copolymer.

Background of the Invention

Heap leaching is a process used in the mining industry to extract copper, uranium, gold, silver and other compounds from ores. Ores used for this operation tend to be low grade ores. Such leaching operations are typically carried out in large heaps. The mineral or metal bearing ore may suitably be crushed to reduce the ore to a smaller particle size which expose more of the metal values at the surface. It is then necessary to form the crushed ore into agglomerates which can more easily be stacked into a heap. Once formed into a heap a leaching solution would be applied and allowed to percolate through the agglomerated ore to enable metal values to react and dissolve into the leaching solution from which the metal can be extracted. Typically, the leaching solution may be a strong mineral acid, such as sulfuric acid, or a caustic cyanide solution, such as aqueous sodium cyanide.

Many heap leaching operations involve ore crushing, agglomeration, stacking system, heap leaching area and reclaim the system for the final leach residue. This reclaimer system includes, a racetrack, bucket wheel excavator, belt conveyors and a radial spreader to deposit the residue in a leach residue dump.

It is known to use agglomeration agents to form metal ore into agglomerates and such agglomeration agents may for instance be natural or synthetic polymers. US Patent 4875935 relates to a method for extracting copper from copper minerals by heap leaching with dilute sulfuric acid which comprises agglomerating the copper mineral fines prior to their being formed into a heap. The agglomeration is effected with an agglomerating agent comprising an anionic acrylamide copolymer containing at least 5 mol % of carboxylate or sulfonate groups and having a molecular weight of at least 100,000.

US Patents 4898611 and 5100631 describe a heap leaching process in which low grade gold and silver ores are leached by spraying cyanide solution onto a large heap of ore. This document discusses the problem associated with segregation of fines in building the heap and migration of fines during percolation which can result in channelling and/or blinding. Reference is given to a development by the US Bureau of Mines in which the ore is agglomerated with 5-20 Ibs/ton cement binder and about 12% water. It is noted in US 4898611 that this does not totally solve the problem leading to long leach cycles and/or slow percolation rates. The reference also acknowledged that the Bureau of Mines also employed a high molecular weight polyethylene oxide (PEO). However, it was noted that PEO does not achieve as high a flow rate and the agglomerates break down more rapidly than vinyl addition polymers. US 4898611 seeks to overcome this problem by using a high molecular weight soluble vinyl addition polymer added to the agglomerating liquid. The agglomerating agent is a water-soluble vinyl polymer having a molecular weight of at least 500,000. Various vinyl addition polymers are proposed including polymers of acrylamide and water-soluble polymers of acrylic acid, methacrylic acid. Anionic and cationic polymers are also described. It is claimed that the polymer helps tie up the fines in the agglomerating step enabling the cement when it is used as a coagglomerating agent to better contact and bind the fines.

US patents 5077022, 5112582, 5186915 and 5211920 reveal an agglomerating agent and method for use in heap leaching of mineral bearing ores. Moderate to high molecular weight anionic polymer either alone or in combination with cement are said to provide a highly efficient agglomerating agent. The anionic polymer said to be preferably a copolymer of acrylamide and acrylic acid and preferably having a molecular weight of from about 1 to 8 million or higher. US patents 5512636 and US 5668219 each describe an agglomerating agent and method of using it in heap leaching of mineral bearing ores. Cationic polymers alone or in combination with cement and lime are proposed and claimed to be highly effective agglomerating agent in acidic or alkaline leaching operations. The cationic polymers are said to be preferably graft copolymers, block copolymers or linear copolymers of acrylamide and diallyl dimethyl ammonium chloride. The cationic polymers may include graft polymers having a grafted segment preferably an ethylenically unsaturated carboxylic acid, amide, C-i-Cs alkyl ester or hydroxy related Ci-C ₈ alkyl ester and block polymers carrying a polymeric segment obtained from polymerisation of hydrophobic or water insoluble monomers.

International application WO 99/63123 teaches heap leach agglomeration/ percolation extraction aids for enhanced gold and silver recovery. The disclosure describes adding polypropylene glycol and alkylphenol ethoxylate in a paraffin oil solvent with the cyanide lixiviant to the ore heap. The publication does not reveal which if any agglomerating agent is used form the heaps, however in the description of the background reference is given to cement as an agglomerating agent.

International application WO 99/20803 concerns a method for extracting a precious metal from mineral fines by heap leaching with dilute sulfuric acid and comprises agglomerating the mineral fines prior to the formation into a heap with an agglomeration agent. The agglomerating agent is said to be a composition comprising sequential addition of a first polymer and then a second polymer to the fines. Preferred first polymers are said to be polyacrylamide and 70/30 mol % polyacrylamide/sodium acrylate and preferred second polymers are said to be poly diallyl dimethyl ammonium chloride, 90/10 mol % poly acrylamide/diallyl dimethyl ammonium chloride and 99/1 mol % poly diallyl dimethyl ammonium chloride/vinyl trimethoxysilane.

An article entitled, Review of agglomeration practice and fundamentals in heap leaching by Sylvie C Bouffard (2005), Mineral Processing and Extractive Metallic a Review, ISSN 0882-7508 (Print) reviews agglomeration practices for precious metal and copper heap leaching. According to this article these industries preferred drum to convey agglomeration, particularly for clayey ore or ore having a high fines content. Further, it appears that precious metal heap leaching operation opt for cement while copper ores are agglomerated with water and up to 40 kg sulfuric acid/t of ore without binder.

A report entitled, Novel Binders and Methods for Agglomeration of Ore by S.K. Kawatra et al. issued October 2006, Department of Chemical Engineering, Michigan Technological University reviews heap leaching methods being used to recover metal from low-grade ore deposits. The document identifies problems faced during heap leaching relating to the migration of fine-grained particles through the heap, forming impermeable beds which result in poor solution flow.

A problem that can occur is in handling leach residues from the leaching process for certain ores. This may occur due to the higher moisture and clay content in the leach residue when clayey ore is being processed. In some cases, it may be difficult to transport the leach residue by a belt conveyor system. This may be due to the transference points of the material which clog the system and may result in stopping the operation in order to clean the lines. This can reduce the availability of the reclaimer system which can in turn limit the intake of fresh ore and ultimately the production of metal from the leachate. A further problem which can occur is the final disposal of the leach residue when processing clayey ores. In this case there may be difficulty distributing the leach residue into the leach residue dump. This can lead to a reduction in the angle of repose of this waste material which indirectly is related to the clay and high moisture content. In such situations such a reduction in the angle of repose may reduce stability of the heap.

The objective of the present invention was to overcome the problem related to the heap leaching of such high moisture containing and clayey ores. It would be desirable to provide a system that overcomes all the aforementioned problems. In particular, it would be desirable to develop an agglomeration process which can be applied to a range of different metal containing ores including the clayey ores especially highly clayey ores that have a high moisture content. Desirably such a development should improve the agglomeration process by the addition of a suitable agglomeration agent which facilitates the formation of suitable agglomerates which can more easily be formed into stable heaps and permit efficient extraction of the metal values when percolating the leaching solution through the heap. Preferably the solution to the objective should be applicable for wide range of metal bearing ores and not just the clayey ores or clayey ores with high moisture content.

Summary of the Invention

According to the present invention we provide a process of heap leaching metal from a metal bearing ore comprising the steps: a) agglomerating the ore with an agglomeration agent to form an agglomerated ore, b) forming the agglomerated ore into a heap; and c) then leaching the agglomerated ore by percolating a leaching solution through the heap which extracts the metal from the agglomerated ore for subsequent recovery, wherein the agglomeration agent comprises a hydrophobically associating copolymer.

The invention further includes the use of a copolymer as an agglomeration agent in the process of heap leaching, wherein the agglomeration agent comprises a hydrophobically associating copolymer.

The inventors have found that employing an agglomeration agent that comprises a hydrophobically associating copolymer in the heap leaching process the physical properties of the agglomerated ore can be improved. In this respect the ore agglomerates incorporated the fines and held together more strongly even when percolating the leaching solution through the agglomerates in the heap. Furthermore, the inventors discovered that the aforementioned problems when using metal ores that contain high clay content and exhibit high moisture levels could be overcome.

Description of Drawings

Figure 1 is a graphical representation showing the migration of fines results from the soak tests of Example 1 employing different doses of inventive agglomeration agent. Figure 2 is an image of the agglomerated ore in a heap from agglomeration test work of Example 2 using only raffinate for the agglomerates and no inventive agglomeration agent.

Figure 3 is an image of the agglomerated ore in a heap from agglomeration test work of Example 2 using 50 g/tonne inventive agglomeration agent form the agglomerates.

Figure 4 is an image of the agglomerated ore in a heap from agglomeration test work of Example 2 using 100 g/tonne inventive agglomeration agent form the agglomerates.

Figure 5 is an image of the agglomerated ore in a heap from agglomeration test work of Example 2 using 500 g/tonne inventive agglomeration agent form the agglomerates.

Figure 6 is a representation of the soak test procedure in which the metal bearing ore is agglomerated in a rotating drum with raffinate and a chosen agglomeration agent. As the drum is rotated the agglomeration agent binds the fine particles to the more coarse particles. In the second step the agglomerates are placed onto a Tyler 10 mesh screen and left to air dry or cure for 24 hours. The screen is then lowered into a sulfuric acid or other leaching solution, simulating the acidic conditions which would be found in a heap. After 30 minutes, the acid solution is decanted and the fine material which has passed through the screen collected, dried and weighed. Detailed Description of the Invention

The present invention relates to a heap leaching process in which a copolymer is employed as an agglomeration agent, herein also called a hydrophobically associating copolymer. A hydrophobically associating copolymer comprises monomer units which impart hydrophobically associating properties.

The hydrophobically associating copolymer suitably comprises monomer units derived from at least one ethylenically unsaturated hydrophobically associating monomer C. Preferably the hydrophobically associating copolymer comprises monomer units derived from at least one anionic monoethylenically unsaturated, hydrophilic monomer A, at least one uncharged, monoethylenically unsaturated hydrophilic monomer B, and at least one unsaturated, hydrophobically associating monomer C.

The hydrophobically associating monomers C preferably comprise, as well as an ethylenically unsaturated group, a hydrophobic group which, after the polymerisation, is responsible for the hydrophobic association of the copolymer formed. They preferably further comprise hydrophilic molecular components which impart a certain water solubility to the monomer.

In a particularly preferred embodiment, the at least one of the hydrophobically associating monomer C is a monomer of general formula (I)

H ₂ C=C( R ¹ )-R ² -O-(-C H ₂ -C H ₂ -O-) _k -(-C H ( R ⁵ )-C H ( R ³ )-O-)i-(-C H ₂ -C H ₂ -O-) _m -R ⁴ (I) wherein k: is a number from 10 to 150, preferably from 20 to 30;

I: is a number from 5 to 20; m: is a number from 0 to 30;

R ¹ : is H or methyl;

R ² : is independently a single bond or a divalent linking group selected from the group consisting of -(CH ₂ ) _n - and -O-(CH ₂ ) _n ’ -, where n is a natural number from 1 to 6 and n’ is a natural number from 2 to 6;

R ³ and R ⁵ : are each independently hydrogen or a hydrocarbyl radical having 1 to 6 carbon atoms or an ether group of the general formula -CH ₂ -O-R ³ ’ where R ³ ’ is a hydrocarbyl radical having at least 2 carbon atoms; with the proviso that the sum total of the carbon atoms in all hydrocarbyl radicals R ³ or R ³ ‘ and R ⁵ is in the range from 10 to 50 and preferably in the range from 20 to 40; and

R ⁴ : is independently H or a hydrocarbyl radical having 1 to 4 carbon atoms.

In a preferred embodiment, R ¹ is H. The - (CH2) _n - and -(CH2) _n ’ groups of R ² may be straight-chained or branched. In a preferred embodiment, the -(CH2) _n - and -(CH2) _n ’ groups are straight-chained.

In a preferred embodiment, the R ² group is -(C enin a preferred embodiment, n is 1 , 2 or 3. In a more preferred embodiment, n is 1 .

In another preferred embodiment, each R ² group is a -O-(CH2)n’ group.

In another preferred embodiment, n’ is 2, 3, or 4. In a more preferred embodiment, n’ is 4.

In a particularly preferred embodiment, each R ² is independently selected from - CH ₂ - and -O-CH2-CH2-CH2-CH2-, and preferably is -O-CH2-CH2-CH2-CH2-.

Suitably the monomers C of formula (I) additionally have a polyalkyleneoxy radical consisting of -(-CH ₂ -CH ₂ -O-)k , -(-CH(R ⁵ )-CH(R ³ )-O-)i and optionally -(-CH ₂ - CH2- O- ) _m units, the units being arranged in block structure in the sequence shown in formula (I). The transition between the blocks may be abrupt or else continuous.

In a preferred embodiment, the number of ethyleneoxy units k is a number from 12 to 100, more preferably 15 to 80, even more preferably 20 to 30 and even more preferably from 22 to 26 and even more preferably from 23 to 26. It will be apparent to the person skilled in the art in the field of polyalkylene oxides that the numbers mentioned are mean values of distributions.

In a preferred embodiment, R ³ is independently a hydrocarbyl radical having at least 2 carbon atoms and preferably is a hydrocarbyl having 2 to 14 carbon atoms, more preferably 2 to 4, and even more preferably having 2 or 3 carbon atoms. The hydrocarboyl radical may be an aliphatic and/or aromatic, linear or branched carbon radical. In a preferred embodiment, R ³ is selected from ethyl, n-propyl, n-butyl, n-pentyl, n- hexyl, n-heptyl, n-octyl, n-nonyl or n-decyl and phenyl. In a more preferred embodiment, R ³ is selected from n-propyl, n-butyl, n-pentyl.

In a particularly preferred embodiment, R ³ is selected from ethyl or n-propyl. Thus, in a preferred embodiment, the -(-CH2-CH(R ³ )-O-)I block in formula (I) is a polybutyleneoxy block or a polypentyleneoxy block.

In another preferred embodiment, R ³ may is an ether group of the general formula - CH2-O-R ³ ’. In a preferred embodiment, R ³ ’ is an aliphatic and/or aromatic, linear or branched hydrocarbyl radical having at least 2 carbon atoms. In a preferred embodiment, R ³ ’ comprises from 2 to 10 carbon atoms and more preferably at least 3 carbon atoms. In another preferred embodiment, R3’ is selected from n-propyl, n- butyl, n-pentyl, n-hexyl, 2-ethylhexyl, n-heptyl, n-octyl, n-nonyl, n-decyl or phenyl.

It will be apparent to the person skilled in the art in the field of polyalkylene oxides that the orientation of the hydrocarbyl radicals R ³ may depend on the conditions in the alkoxylation, for example on the catalyst selected for the alkoxylation in the polymerisation reaction of the copolymer of the present invention. The alkyleneoxy groups can thus be incorporated into the monomer C in the orientation -(-CH2- CH(R ³ )-O-)- or else the inverse orientation -(-CH(R ³ )-CH2-O-)I- The representation in formula (I) shall therefore not be regarded as being restricted to a particular orientation of the R ³ group.

The number of alkyleneoxy units I is a number from 5 to 20 and preferably from 8.5 to 17.25, with the proviso that the sum total of the carbon atoms in all hydrocarbyl radicals R ³ or R ³ ‘ is in the range from 20 to 40 and preferably from 25.5 to 34.5. If the R ³ radicals are an ether group -CH2-O-R ³ ‘, the proviso applies that the sum total of the hydrocarbyl radicals R ³ ‘ is in the range from 20 to 40 and preferably from 25.5 to 34.5, not including the carbon atom in the linking -CH2-O- group in -CH2-O-R ³ ‘.

A preferred embodiment relates to an above-described copolymer comprising a monomer C wherein R ³ is ethyl and I is a number from 12.75 to 17.25, preferably 13 to 17, and more preferably 14 or 16. A further preferred embodiment relates to an above-described copolymer comprising a monomer C where R ³ is n-propyl and I is a number from 8.5 to 11 .5, preferably 9 to 11 , for example 10 or 11 . It will be apparent to the person skilled in the art in the field of polyalkyleneoxides that the numbers mentioned are mean values of distributions.

The optional block -(-CH2-CH2-O-) _m is a polyethyleneoxy block. The number of ethyleneoxy units m is a number from 0 to 15, preferably from 0 to 10, more preferably from about 0.1 to about 10, more preferably from 0.1 to about 5, even more preferably from about 0.5 to about 5 and most preferably from about 0.5 to about 2.5. It will be apparent to the person skilled in the art in the field of polyalkylene oxides that the numbers mentioned are mean values of distributions.

In a preferred embodiment, R ⁴ is selected from H, methyl and ethyl. In a more preferred embodiment, R ⁴ is selected from H or methyl. In a particularly preferred embodiment, R ⁴ is H.

In another preferred embodiment, R ⁵ is hydrogen.

In the monomers C of the formula (I), a terminal, monoethylenic group is joined to a polyalkyleneoxy group with block structure, more specifically first to a hydrophilic block having polyethyleneoxy units and the latter in turn to a second hydrophobic block formed from alkyleneoxy units, preferably at least butyleneoxy units or units of higher alkylene oxides and more preferably from butyleneoxy or pentyleneoxy units. The second block may have a terminal -OR ⁴ group, especially an OH group. The end group need not be etherified with a hydrocarbyl radical for hydrophobic association; instead, the second block -(-CH2-CH(R ³ )-O-)I itself having the R ³ or R ³ ‘ radicals may be responsible for the hydrophobic association of the copolymers prepared using the monomers C. Etherification is just one option which can be selected by the person skilled in the art according to the desired properties of the copolymer.

It will be apparent to the person skilled in the art in the field of polyalkyleneoxy block copolymers that the transition between the two blocks, according to the method of preparation, may be abrupt or else continuous. In the case of a continuous transition, there is a transition zone comprising monomers of both blocks between the blocks. If the block boundary is fixed in the middle of the transition zone, the first block - (- CH2-CH2-O-)k may correspondingly still have small amounts of -(-CH2-CH(R ³ )-O- )- units and the second block -(-CH(R ⁵ )-CH(R ³ )-O-)i small amounts of -(-CH2- CH2-O-)- units, in which case these units, however, are not distributed randomly over the block but are arranged within the transition zone mentioned. More particularly, the optional third block (-CH2-CH2-O-) _m may have small amounts of units -(-CH ₂ -CH(R ³ )-O-)-.

Thus, monomer C of formula (I) comprises (-CH2-CH2-O-)k, (-CH(R ⁵ )-CH(R ³ )-O-)i and optionally -(-CH2-CH2-O-) _m units which are arranged in block structure in the sequence shown in formula (I). "Block structure" in the context of the present invention means that the blocks are formed from the corresponding units to an extent of at least 85 mol%, preferably to an extent of at least 90 mol%, more preferably to an extent of at least 95 mol%, based on the total amount of the respective block.

This means that the blocks, as well as the corresponding units, may have small amounts of other units (especially other polyalkyleneoxy units). More particularly, the optional polyethyleneoxy block -(-CH2-CH2-O-) _m comprises at least 85 mol%, preferably at least 90 mol%, based on the total amount of the block, the unit (-CH2-CH2-O-). More particularly, the optional polyethyleneoxy block -(-CH2-CH2- O-) _m consists of 85 to 95 mol% of the unit (-CH2-CH2-O-) and of 5 to 15 mol% of the unit (-CH(R ⁵ )-CH(R ³ )-O-).

In a preferred embodiment, k, I and m are selected as follows: k: is a number from 23 to 26;

I: is a number from 8.5 to 17.25; and m: is a number from 0 to 15.

In a particularly preferred embodiment of formula (I), k: is a number from 23 to 26;

I: is a number from 12.75 to 17.25; m: is a number from 0 to 15, preferably 0 or preferably 0.5 to 10;

R ¹ : is H; R ² : is a divalent linking group -O-(CH2) n* - where n' is 4;

R ³ : is independently a hydrocarbyl radical having 2 carbon atoms; and

R ⁴ : is H; and

R ⁵ : is H.

In another particularly preferred embodiment of formula (I), k: is a number from 23 to 26;

I: is a number from 8.5 to 11 .5; m: is a number from 0 to 15;

R ¹ : is H;

R ² : is a divalent linking group -O-(CH2)n‘ - where n' is 4;

R ³ : is a hydrocarbyl radical having 3 carbon atoms; and

R ⁴ : is H; and

R ⁵ : is H.

In another embodiment, the monomer C of formula (I) in the copolymer is a mixture of a monomer C of formula (I) wherein m is 0 and a monomer C of the formula (I) wherein m is 1 to 15, preferably 1 to 10. In a preferred embodiment, the weight ratio of the monomer C of the formula(l) wherein m is 0 and the monomer C of the formula (I) wherein m is 1 to 15, preferably 1 to 10, is in the range from 19 : 1 to 1 : 19, preferably in the range from 9 : 1 to 1 : 9. This mixture of monomer C of the formula (I) wherein m is 0 and monomer C of the formula (I) wherein m is 1 to 15, more preferably gives rise to a mean value (averaged over all monomers C in the copolymer) for m from about 0.1 to about 10, preferably from about 0.1 to about 5, more preferably from about 0.5 to about 5 and even more preferably from about 0.5 to about 2.5.

Methods for preparing monomers C of formula (I) are for example described in WO 2014/095608, which is incorporated herein by reference.

In another preferred embodiment, the monoethylenically unsaturated water-soluble monomer C is selected from the group of H ₂ C=C( R ¹ )-R ² -O-(-C H ₂ -C H ( R ⁵ ')-O-)k-(-C H (R ⁵ )-C H ( R ³ )-O-)i-R ⁴ ( I A)

H ₂ C=C(R ¹ )-O-(-CH ₂ -CH(R ⁵ ’)-O-) _k -R ⁶ (H)

H ₂ C=C(R ¹ )-(C=O)-O-(-CH ₂ -CH(R ⁵ ’)-O-)k-R ⁶ (HI)

H ₂ C=C(R ¹ )-(C=O)-O-R ⁶ (IV)

(V)

(VI) wherein

R ¹ , R ² , R ³ , R ⁴ , k and I of formula (IA), (II), and (III) may be selected as defined above for formula (I).

In the -(-CH ₂ -CH(R ⁵ ’)-O-)k block of formula (IA), (II) and (III), each R ⁵ ’ is independently H, methyl or ethyl, preferably H or methyl. In a preferred embodiment at least 50 mol% of the R ⁵ ’ radicals are H. Preferably at least 75 mol% of the R ⁵ ’ radicals are H, more preferably at least 90 mol%, and they are most preferably exclusively H. The block mentioned is thus a polyoxyethylene block which may optionally also have certain proportions of propylene oxide and/or butylene oxide units, preferably a pure polyoxyethylene block.

R ⁶ in formula (II) or (III) or (IV) is an aliphatic and/or aromatic, straight-chain or branched hydrocarbyl radical having 8 to 40 carbon atoms, preferably 12 to 32 carbon atoms. In a preferred embodiment, R ⁶ may comprise n-alkyl groups such as n-octyl, n-decyl or n-dodecyl groups, phenyl groups, and especially substituted phenyl groups. Substituents on the phenyl groups may be alkyl groups, for example Ci-Ce-alkyl groups, preferably styryl groups. Particular preference is given to a tristyrylphenyl group.

The hydrophobically associating monomers of the formulae (II) and (III) and the preparation thereof are known in principle to those skilled in the art, for example from EP 705 854 A1 .

RA, RB, RC, RD, RE, RF in formula (V) are each independently hydrogen or a hydrocarbylene radical containing 1 to 4 carbon atoms;

Q is a hydrocarbylene radical containing 1 to 8 carbon atoms; and

RG is an hydrocarbyl radical containing 8 to 30 atoms;

X is a counterion with a negative charge.

In a preferred embodiment, X is a halide selected from the group including bromide, or chloride, iodide, fluoride. However, X may also be any other suitable counterion. R _a , Rb and R _c in formula (VI) are each independently selected as hydrogen or a hydrocarbyl radical containing 1 to 4 carbon atoms.

Rd in formula (VI) may be selected as a saturated or unsaturated alkyl containing 4 to 18 carbon atoms.

G in formula (VI) is -O- or -NH-.

In a preferred embodiment, at least 50% by weight, preferably at least 80% by weight, of the hydrophobically associating monomers are monomers C of the general formula (I), (IA), (II), (III), (IV), (V) and (VI), and particular preference is given to using only monomers C of the general formula (I), (II), (III), (IV), (V) and/or (VI) as hydrophobically associating monomers in the inventive copolymer. Particular preference is given to using only monomers C of the general formula (I) as the hydrophobically associating monomers to prepare the copolymers used according to the present invention.

In a preferred embodiment, the amount of the monoethylenically unsaturated, hydrophobically associating monomers C is from about 0.1 to about 15% by weight, based on the total amount of all monomers in the copolymer, preferably from about 0.1 to about 10% by weight, more preferably from about 0.2 to about 5% by weight and even more preferably from about 0.5 to about 2% by weight.

In another preferred embodiment, the copolymer used according to the present invention comprises from about 0.1 to about 15% by wt. and preferably from about 0.5 to about 4 % by wt. at least one monomer C, wherein the % by wt. is based on the total weight of all monomers in the copolymer.

In another preferred embodiment, the hydrophobically associating copolymer used according to the present invention further comprises monomer units derived from at least one anionic monoethylenically unsaturated, hydrophilic monomer A. In a preferred embodiment, the at least one monomer A comprises at least one group selected from the group consisting of -COOH, -SO3H, -PO3H2, salts thereof and mixtures of any of the foregoing.

Examples of Monomer A comprising -COOH groups include, but are not limited to, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid or fumaric acid. In one embodiment, the Monomer A comprising -COOH groups comprises crotonic acid, itaconic acid maleic acid or fumaric acid.

Examples of monomers A comprising sulfonic acid groups include vinylsulfonic acid, allylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2- methylpropanesulfonic acid, 2-acrylamidobutanesulfonic acid, 3-acrylamido-3- methylbutanesulfonic acid or 2-acrylamido-2,4,4-trimethylpentanesulfonic acid.

Preference is given to vinylsulfonic acid, allylsulfonic acid or 2-acrylamido-2- methylpropanesulfonic acid. In a preferred embodiment, the at least one monomer A is 2-acrylamido-2-methyl- propane sulfonic acid (AMPS or ATBS).

Examples of monomers A comprising phosphonic acid groups comprise vinylphosphonic acid, allylphosphonic acid, N-acrylamidoalkylphosphonic acids, N- methacrylamidoalkylphosphonic acids acryloyloxyalkylphosphonic acids, methacryloyloxyalkylphosphonic acids, preference being given to vinylphosphonic acid.

In one preferred embodiment, the copolymer used according to the present invention comprises monomer units derived from at least one unsaturated, hydrophobically associating monomer C and at least one anionic monoethylenically unsaturated, hydrophilic monomer A.

In another preferred embodiment, the hydrophobically associating copolymer used according to the present invention further comprises monomer units derived from at least one uncharged, monoethylenically unsaturated hydrophilic monomer B. It is even more preferred that the copolymer comprises monomer units derived from at least one unsaturated, hydrophobically associating monomer C and at least one uncharged, monoethylenically unsaturated hydrophilic monomer B.

In a preferred embodiment, the monoethylenically unsaturated, hydrophilic monomer B is selected from the group consisting of acrylamide, methacrylamide, N-methyl acrylamide, N-methyl methacrylamide, N,N’-dimethyl acrylamide, N,N’-dimethyl methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, uncharged vinylamides such as vinylformamide or N-vinylpyrrolidone; and mixtures thereof. Preference is given to acrylamide or methacrylamide, especially acrylamide. In a preferred embodiment, when mixtures of different monomers B are used, at least 50 mol% of the monomers B should be acrylamide or methacrylamide, and preferably acrylamide.

In a preferred embodiment, the hydrophobically associating copolymer comprises monomer units derived from i. at least one anionic monoethylenically unsaturated, hydrophilic monomer A, ii. at least one uncharged, monoethylenically unsaturated hydrophilic monomer B, and iii. at least one unsaturated, hydrophobically associating monomer C.

The monomers may of course also be the salts of the anionic acidic monomers. Suitable counterions comprise especially alkali metal ions such as Li ⁺ , Na ⁺ or K ⁺ , and ammonium ions such as NH4 ⁺ or ammonium ions with organic radicals.

It is preferred that in a copolymer comprising monomer units derived from Monomers A and B, Monomer A and B are miscible with water in any ratio, but it is sufficient for execution of the invention that the inventive copolymer possesses the water solubility mentioned at the outset. In a preferred embodiment, the solubility of the monomers A and B in water at room temperature should be at least 50 g/l, preferably at least 150 g/l and more preferably at least 250 g/l.

In a preferred embodiment, monomer A is AMPS and/or monomer B is acrylamide.

In yet another preferred embodiment, the copolymer comprises about 2 % by wt. at least one monomer C, about 48 % by wt. at least one monomer A and about 50 % by wt. at least one monomer B, wherein monomer A is preferably AMPS and/or monomer B is preferably acrylamide. The % by weight is in each case based on the total weight of monomers in the copolymer.

In one embodiment, the copolymer used according to the present invention has been made by polymerisation of the monomer blend in the presence of at least one branching agent. The branching agent may cause covalent or ionic cross linking through pendant groups, (e.g., by use of a glycidyl ether or multivalent metal salt) but preferably the branching agent is a diethylenically unsaturated monomeric branching agent. The amount of branching agent is preferably in the range of from about 2 to about 200 ppm and more preferably from about 10 to about 100 ppm. The ppm values are based on the total weight of the copolymer. In a preferred embodiment, the at least one branching agent is selected from methylene bis acrylamide (MBA) and tetra allyl ammonium chloride (TAAC) or combinations thereof. In one embodiment, the copolymer does not comprise monomers derived from monomers C of formula (V) or (VI).

In another preferred embodiment, the copolymer does not comprise monomers derived from Rosin or derivatives thereof. Rosin is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene components. It essentially consists of abietic acid. Common derivatives of Rosin are, for example, esters of Rosin compounds. Examples of Rosin and derivatives thereof are CAS No. 8050-08-7, CAS No. 65997- 06-0, CAS No. 68425-08-1 , CAS No. 61790-50-9, CAS No. 61790-10 51-0 and CAS No. 68783-82-4.

In another preferred embodiment, the copolymer according to the present invention does not comprise a polyamide polyamine chain as a side chain.

In another preferred embodiment, the copolymer according to the present invention does not comprise a COOH or COO’ residue as a side chain. Thus, in this embodiment, the copolymer according to the present invention is not derived from monomers of acrylic acid and/or methacrylic acid.

In a preferred embodiment, the molecular weight of the copolymer is at least 300,000 Da, preferably at least 500,000 Da and even more preferably at least 1 ,000,000 Da. The person skilled in the art will be aware how to determine the molecular weight of a copolymer, which is typically determined as an average, preferably as the mass average molecular weight (Mw) or as a number-average molecular weight (Mn). The molecular weight of the copolymer may be determined for example by permeation chromatography which is particularly suitable for the determination of the molecular weight for copolymers having a molecular weight up to about 1 million Da.

In the ideal case, the copolymers used in accordance with the invention should be miscible with water in any ratio or water soluble. According to the invention, however, it is sufficient when the copolymers are water-soluble for instance at least at the desired use concentration and at the desired pH. In general, the solubility of the copolymer in water at room temperature (e.g. 25°C) under the use conditions should be at least about 10 g/l or at least 25 g/l.

It may be desirable to employ a solubility aid with the hydrophobically associating copolymer in order to facilitate the dissolution of the copolymer. Such a solubility aid may be combined during the step of dissolving the copolymer but usually, where employed, such solubility aid may be incorporated with the hydrophobically associating copolymer prior to dissolving and/or prior to application. Generally, the solubility aid would be combined as a dry particulate powder with dry particulate powder hydrophobically associative copolymer. Desirably the solubility aid may be any basic monovalent cation containing compound, such as alkali metal oxides, alkali metal hydroxides, alkali metal carbonates or alkali metal bicarbonates. Desirably, the alkali metal will be selected from sodium or potassium. A particularly preferred solubility aid is sodium carbonate.

The metal bearing ore may be any such ore typically treated in a heap leaching process. Suitably, the ore may be selected from the group consisting of copper ores, nickel ores, uranium ores, molybdenum ore, vanadium ore, zinc ore, gold ores and silver ores. For the purposes of the present invention other metal bearing ore may be or contain residues from ores or from mined materials that have been processed. For instance, the metal bearing ore may be lignite powerplant residues, for instance fly ash. Such lignite powerplant residues may contain metal values, particularly vanadium as the main metal value component and may also contain alkali metals and rare metals.

Typically, copper ore may be copper oxide ore, mixed and secondary sulfide ores. Copper containing ores are often classified into two categories: oxidic and sulfidic ores. Oxidic ores, such as cuprite, malachite, and azurite, are often found near the surface as they are oxidation products of the deeper secondary and primary sulfidic ores. Sulfidic ores include for instance chalcopyrite, bornite and chalcocite. Due to the chemical nature of copper oxides and secondary sulfides, mines typically treat the ore with hydrometallurgical processes, including heap leaching, solvent extraction and electrowinning. The metal bearing ore may comprise a significant level of very small sized particles known as fines. This is particularly so with low grade ores including those clayey ores that contain high levels of clay. Typically, the fine particles are present predominantly in the clay component of the metal bearing ore. During the crushing process more of the clay component may be exposed which in turn releases the fine particles associated with the clay. The level of freely available or unassociated fines in such clayey ores tends to increase during crushing of the ore. The ores may comprise freely available or unassociated fines 10 Tyler mesh size (1680 pm or below) content of from 10% by weight to 40%, for instance from 20% by weight to 30% by weight, based on total weight of ore. In some cases the fines contained in the initial ore may be of a significantly smaller size, for instance 100 Tyler mesh (150 pm or below) being present in an amount of up to 40%, for instance from 10% by weight to 40% by weight, in particular from 20% by weight to 30% by weight, based on the total weight of the ore.

The metal bearing ore may contain significant levels of clay. Such ores are often referred to as clayish ores. In the heap leaching industry, it is generally understood that particles with sizes below 100 Tyler mesh are considered clays. These small particles are often bound to larger particles in the mined ore before processing. In cases where the ore is crushed resulting in the breaking up of the larger particles a distribution of particle sizes is often created. In the case of copper ore the particle size distribution includes fine particles, below 100 Tyler mesh. Nevertheless, these fine particles typically become bound to the larger particles during the agglomeration step. It is also possible that such small particles may even become bound to the larger particles by the action of water in acid to form liquid bridges. Nevertheless, in order to ensure that these fine particles remain bound in the agglomerates that are formed in the agglomeration step it is important that the so formed agglomerates have sufficient strength. In cases where the agglomerates are bound together insufficiently the action of the heap leaching with the leaching solution can break up the agglomerates releasing fine particles which can be washed to the bottom of the heap. Such a release of fine particles could then block the pores in the heap leach pads or other filter membranes upon which the heap sits. This could obstruct or restrict the flow of the pregnant leaching solution. The hydrophobically associating agglomeration agent of the present invention improves the strength of the agglomerates facilitates the fines being more strongly bound to the agglomerates thereby avoiding any significant blocking of the pores in the heap leach pads or other filter membranes. As such, the pregnant leaching solution would easily flow from the heap.

The metal bearing ore may contain oversized particles and in some cases quite large sized chunks which may not be so easy to agglomerate and the leaching step may then not be quite so effective. In such cases it would be desirable to reduce the size by breaking the ore into smaller sized particles. Thus, the metal bearing ore may suitably be crushed to reduce the ore to a smaller particle size which exposes more of the metal values at the surface. Desirably the metal bearing ore is crushed prior to the agglomeration step (a). Crushing may be achieved by any conventional crushing apparatus used for achieving the desired size reduction for a heap leaching process. Generally, crushers normally employed for the size reduction of the metal bearing ore include for instance gyratory, rotary, jaw and cone crushers. The crushing apparatus may for instance be gyratory crushers and/or cone crushers. Frequently, crushing plants may employ a primary crusher, which could be either a rotary or jaw crusher, and 2 or 3 stages of cone crusher with different openings in the second or third stages. In some cases, screens may be employed to limit the maximum particle size of the ore leaving the crushing plant. Typically, this may be a series of crushing devices, for instance a gyratory primary crusher followed by a standard secondary cone crusher from which the crushed ore may be classified using a screen through which adequately sized ore particles would pass and then be sent to the agglomeration step and particles that did not pass through the screen returned to the standard secondary cone crusher and/or optionally passed to a short head tertiary cone crusher after which the crushed ore would be classified through a screen through which adequately sized or particles would pass and be sent to the agglomeration step and particles that did not pass through the screen returned to the short head tertiary cone crusher.

The agglomeration agent hydrophobically associating copolymer of the invention may be added as a powder or as an aqueous solution. The aqueous solution of the agglomeration agent copolymer may be formed by dissolving the copolymer in water or in raffinate. The raffinate may be described as the liquid resulting from the pregnant leaching solution following the metal extraction process and thus substantially depleted of the metal values. The agglomeration agent copolymer may be added to the metal bearing ore prior to the agglomeration step but usually is added into or during the agglomeration step. The agglomeration copolymer should desirably be mixed into the metal bearing ore to allow integration of the agglomeration agent throughout the ore particles. Generally, the movement of the ore in the agglomeration step often achieves sufficient integration. When the copolymer agglomeration agent is added as an aqueous solution it may be sprayed onto the metal bearing ore during the agglomeration step which may facilitate distribution of the agglomeration agent and hence achieve integration throughout the ore.

In a preferred embodiment, the amount of hydrophobically associating copolymer used as the agglomeration agent for forming the agglomerates of the metal bearing ore in the heap leaching process is generally from about 0.005% wt. to about 0.15 % wt., preferably from about 0.01 % wt. to about 0.1 % wt., and more preferably from 0.025% wt. to 0.075% wt., based on the weight of the metal bearing ore,. By weight of metal bearing ore we mean the total weight of the ore material excavated being processed, which would include the metal containing components, clay material and moisture. The moisture includes moisture already present in the metal bearing ore, and moisture added to the metal bearing ore, for instance prior to or during the agglomeration step and moisture contained with the hydrophobically associating copolymer when it is added as an aqueous solution.

The amount of moisture will vary according to the ore and the process but is typically in the range of from about 7 to about 15%, or from about 8 to about 12% by weight based on the weight of the intimate mixture. Some or all of this moisture may be introduced with the agglomeration agent copolymer, for instance if added as an aqueous solution, and/or an optional treatment polymer, for instance if added as an aqueous solution, and/or by a deliberate addition of water, but often all the moisture is present in the ore and all the additives, such as the agglomeration agent copolymer, would be added dry. In some situations, it may be desirable to include other additives in the agglomeration step with the hydrophobically associating copolymer agglomeration agent of the present invention. Such additives may include other polymers that may act as co-agglomeration agents. Typical polymeric co-agglomeration agent as coadditives may for instance be conventional anionic polyacrylamides, for instance copolymers of sodium acrylate and acrylamide. In other situations, it may be desirable to use inorganic binding agents in conjunction with the hydrophobically associating copolymer, for instance cement. Typically, the use of cement as a coadditive may be employed in the agglomeration of gold ore.

However, it is preferred that no other binder additive is employed. Thus, preferably the hydrophobically associating copolymer is the sole agglomeration agent employed for the agglomeration of the metal bearing ore.

The agglomeration step (a) may be carried out in a rotary drum or on at least one belt conveyor. The agglomerated ore formed during the agglomeration step (a) should ideally be formed as agglomerates. By agglomerates we mean that the particles of metal bearing ore become fused together into a multiplicity of multiparticle entities. These agglomerates should ideally be formed into approximately spherical objects which in the mining and mineral industry are often referred to as pellets. Ideally the agglomeration step should integrate the fines into the so formed agglomerates in order to minimise fines migration during the leaching step. Suitably the fines may be distributed throughout the matrix of the agglomerates.

Typically, the at least one belt conveyor may be arranged at a gradient with one end in an elevated orientation which may facilitate the agglomeration process as the agglomerating ore particles tumble on the belt in the direction of the lower end of the belt conveyor. Another kind of belt conveyor may use point transfers in the belt conveyor system used to transport the ore to the heap. In copper ore leaching acid, water or raffinate may be optionally added with the binder to cure and agglomerate the ore.

Preferably, however, the agglomeration step (a) will be conducted in a drum. The rotary drum may typically consist of a cylinder with one end elevated higher than the other end. The ore would be fed into the rotary drum at the elevated end and the rotary drum would be rotated about its axis. Agglomeration of the ore would take place in the presence of the agglomeration agent copolymer as the drum is rotated and the agglomerating ore progresses towards the lower end. As the rotary drum rotates the ore would tumble and the particles would bind together by the action of the agglomeration agent and form agglomerates. The formed ore agglomerates would then be removed from the drum at the lower end.

In the process of the invention the heap may be formed by any conventional techniques. Usually the heap will sit on heap leach pads which may comprise a single, geo-membrane liner for each pad, often having a minimum thickness of 1.5 mm, but usually thicker. There are different types of heap pads which may be employed depending upon the terrain and location. These include conventional pads of a simple design, dump leach pads, Valley Fills and on/off pads.

Typically, the stacking equipment employed form that heap include conveyors where the agglomerated ore is transported to the location of the heap. Suitably, the conveyors contain moving belts which convey the agglomerated ore onto the heap pad at the start of heap formation and above the heap as the heap is being stacked. Two types of conveyor systems are often employed which include mobile conveyor units which may be combined with radial stacker and a spreader conveyor which may be used for dynamic pads having constant width and height.

Instead of conveyors the heap may be formed using trucks which transport the agglomerated ore to the heap pad and the heap as the ore is being stacked to form the heap. This type of heap stacking may be suitable for run off mine ores.

The leaching step is achieved by percolating a leaching solution through the heap. This can be achieved by applying the leaching solution onto the heap, for instance by the use of sprinklers or drip irrigation. The leaching solution then percolates through the heap extracting the metal values from the ore. The leaching solution may be any of the conventionally used leaching solutions employed for the particular ore being treated. Suitably, the leaching solution may be a strong mineral acid, such as sulfuric acid, or a caustic cyanide solution, such as aqueous sodium cyanide. The leaching solution having percolated through the heap and containing the metal values is often referred to as the pregnant leaching solution.

In one embodiment of the invention the metal bearing ore is selected from any of the group consisting of copper ore, nickel ore and uranium ore, and the leaching solution is sulfuric acid. Typically, the sulfuric acid would be a dilute aqueous solution, for instance having a concentration of from 1 g/L to 15 g/L, suitably 3 g/L to 10 g/L, typically 4 g/L to 8 g/L.

In another embodiment of the invention the metal bearing ore is selected from gold ore or silver ore and the leaching solution is alkaline cyanide, preferably an aqueous solution of sodium cyanide.

The leaching solution containing the extracted metal values, pregnant leaching solution, is typically collected and treated in a process plant to recover the metal. This may typically be by electrowinning. The depleted leaching solution resulting therefrom, often referred to as raffinate, may then be recycled for further use in the heap leaching process. Often, the raffinate may be combined with fresh leaching solution for subsequently percolating through the heap. The raffinate may also be applied during the agglomeration step in order to facilitate agglomeration.

The following examples are intended to illustrate the invention.

Examples

Example 1 - Soak Test - Migration of fines

The Soak Test was carried out following the procedure described in “Novel binders and Methods for agglomeration of ore”, S.K. Kawatra et al. 2006, pages 24-26.

This procedure was employed to establish how well the copper ore agglomerates held together after being agglomerated with raffinate and/or various agglomeration agents while being subjected to acidic conditions which would be found in a heap.

For the soak test procedure, clayish copper ore was agglomerated in a rotating drum with raffinate and a chosen agglomeration agent. The addition of the agglomeration agent helped to bond the fine particles to the coarser ones. It was then placed onto a Tyler 10 mesh screen and left to air dry or cure, 24 hours. Then the screen was lowered into a sulfuric acid and water solution 6 g/L, simulating the acidic conditions which would be found in a heap. After 30 minutes, the acid solution was decanted and the fine material which had passed through the screen was collected, dried, and weighed. This is illustrated in Figure 6.

The agglomeration agents were judged according to the percent of material which has passed through the 10-mesh screen and is termed the amount of fines migrated. Fines migration is the only quantitative measure which is able to be recorded from a Soak test. The fines migration can be calculated by the following equation:

Fines migration = (weight of ore migrated I (weight of particles -10 mesh in ore) x 100

The mesh size could be changed according the ore size distribution to be evaluated

Migration test results with agglomeration agent. As described in the general experimental description above, the ore was agglomerated, after a resting time, was submerged in acid and the fines were measures in the ore before and after the agglomeration when the agglomerated ore was submerged in acid.

Migration tests were conducted with a clayish copper ore, extracted from a copper deposit in North America and being a porphyory copper deposit from the zones of supergene enrichment, having copper oxides, secondary sulfides and also a low proportion of chalcopyrite, crushed to an approximate diameter of 1 inch (2.54 cm). The ore was agglomerated with different dosage of agglomeration agents (0, 50, 100, 200, 300 and 500 g/t). For the blank value without agglomeration agent only the raffinate was used (sulfuric acid in water 6 g/L). Product 1 is the inventive agglomeration agent and is a hydrophobically associating copolymer.

Product 1 : Description and Synthesis

Hydrophobically associating copolymer synthesised according to the preparation of as described in US2017/0101576.

Copolymer of 50% by weight of acrylamide, 48% by weight of Na-ATBS (sodium salt of 2-acrylamido-2methylpropanesulfonic acid) and 2% of macromonomer 1

Macromonomer 1 :

H ₂ C=CH— O— (CH ₂ ) ₄ -O — (EO) ₂₄ .5(BUO)I5.8[(BUO)O.3(EO)5. ₈ ]— H (B1 ) approx. 60 mol %

H ₂ C=CH— O— (CH ₂ ) ₄ — O— (EO) ₂₄ .5(BuO)i5.8— H (B2) approx. 40 mol %

Preparation Method:

A plastic bucket with magnetic stirrer, pH meter and thermometer was initially charged with 146.5 g of a 50% aqueous solution of Na-ATBS, and then the following were added successively: 105.8 g of distilled water, 0.4 g of a commercial silicone-based defoamer (Dow Coming® Antifoam Emulsion RD), 2.8 g of macromonomers 2, 138.2 g of acrylamide (50% solution in water), 1 .2 g of a 5% aqueous solution of diethylenetriaminepentaacetic acid, pentasodium salt and 3.0 g of the nonionic surfactant iCi3-(EO)isH. After adjustment to pH 6 with a 20% or 2% sulfuric acid solution and addition of the rest of the water to attain the desired monomer concentration of 37% by weight (total amount of water minus the amount of water already added, minus the amount of acid required), the monomer solution was adjusted to the initiation temperature of 4° C. The solution was transferred to a thermos flask, the temperature sensor for the temperature recording was inserted, the flask was purged with nitrogen for 30 minutes, and the polymerization was initiated with 1 .6 ml of a 10% aqueous solution of the water-soluble azo initiator 2, 2'-azobis(2-methylpropionamidine) dihydrochloride (Wako V-50), 0.12 ml of a 1 % t-BHPO solution and 0.24 ml of a 1 % sodium sulfite solution. With the onset of the polymerization, the temperature rose to 80° C to 90° C within about 25 min. A solid polymer gel was obtained.

After the polymerization, the gel was allowed to cool down to about 50° C and the gel block was comminuted with the aid of a meat grinder. The gel granules obtained were dried in a fluidized bed drier at 55° C for two hours. This gave hard white granules which were converted to a pulverulent state by means of a centrifugal mill. The weight-average molecular weight M _w was 8 million to 14 million g/mol. The ground polymer was mixed with sodium carbonate in a ratio of 40 : 60 (wt.-%) to give a fine, white to off-white powder with a particle size of 95% < 1 mm and a bulk density of app. 0.7 g/cm ³

Table 1 Migration test results

The fines migration results for each dosage are plotted in the graph presented in Figure 1 .

The experiments show a significant reduction of migrated fines, i.e. in comparison to the blank value without agglomeration agent a significant amount of fines were retained in the agglomerates and not washed out.

Example 2 - Angle of repose and bulk density of the formed heap

Further agglomeration tests were carried out on the clayish copper ore described in Example 1 , to compare the angle of repose using the agglomeration agent by comparison to no agglomeration agent.

The clayish copper ore was crushed to an approximate diameter of 0.75 inches (1 .9 cm). The clayish copper ore was agglomerated in a rotating drum using applying Product 1 agglomeration agent, as defined in Example 1 , dissolved in water as an aqueous solution. The dosage of Product 1 agglomeration agent was 0 g/tonne, 50 g/tonne, 100 g/tonne and 500 g/tonne. The dosages are based on weight of dry Product 1 agglomeration agent on dry weight of clayish ore. A heap was formed from the so formed agglomerated ore. The angle of repose and bulk density of the formed heaps for each dose of agglomeration agent are presented in Table 2. Images of the respective heaps for each dose are given in Figures 2-5. Table 2

It can be seen that with the addition of the agglomeration agent Product 1 there was an increase in the angle of repose and an increase in the bulk density.