The invention relates to a process for extraction of mined material including the use of metal-binding particles. The process of the invention has wide application including for example, leaching metal from an ore heap or extracting water from fine wastes derived from mined material BACKGROUND OFTHE INVENTION

In this specification where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge; or known to be relevant to an attempt to solve any problem with which this specification is concerned.

While the present invention will be described principally with reference to extraction of nickel from laterites, particularly 'heap leaching' of nickel, it will be readily apparent to those skilled in the art that the invention is not so limited but can be applied to leaching of other metals such as copper, zinc, gold, cobalt and manganese from othermined materials including mineral sands, rock, carboniferous material or laterites that have been appropriately pre-processed. Furthermore, the present invention is not limited to extraction of metals in the form of solutions, but can be extended. to the extraction of solutions of other species or chemicals or even water.

Leaching is a technique widely used in the mining industry to extract metals from their native form of mineralisation such as rock, or laterite. It is based on the premise that most metals can form soluble salts in aqueous media. The rock or laterite is contacted with a liquid (leachant) that converts the metal to a metal salt that dissolves in the leachant to create a solution 'pregnant' with the metal. There are many different types or techniques for leaching, including in-situ leaching, heap leaching and vat leaching, ϊn some cases, special leaching processes may be required, for example if material ^' ore is refractory in nature of the material. These techniques include pressure or autoclave leaching and- concentrate leaching. Typically, techniques such as pressure leaching shorten treatment time by increasing the solubility of metals in the leaching solution. In situ leaching

In situ leaching typically involves drilling or blasting holes in an ore deposit to create open pathways. Leaching solution is pumped along the pathways so that it contacts the ore. The solution is then collected and processed. Heap leaching

Minerals are often leached from ore using the simple technique of crushing it into small chunks and creating a 'heap' of the ore chunks on a clay lined leach pad. The heap is then irrigated with a leachant so that it percolates through the heap, often over several weeks. The pregnant solution containing the desired mineral is collected at the base of the heap, typically in ponds. The pregnant solution is then processed to remove the metal - the remaining liquor is either returned to the heap for re-use as leachant, or subjected to chemical treatment processes to. remove hazards, then ejected as waste.

To collect pregnant solution, heaps must be under laid by substantial drainage infrastructure leading to storage ponds. The infrastructure and storage ponds must be specially designed to withstand the aggressive chemicals in the leachant/pregnant solution and the significant weight of the heap.

The heap leaching process has been used for many years for leaching metals such as nickel, copper and gold. For heap leaching of gold, crushed ore is leached with a dilute cyanide solution. For heap leaching of copper and nickel, crushed ore is leached with sulphuric acid.

One of the disadvantages of current heap leaching processes is that the heaps are large, and they use large quantities of leaching solution. The _. leaching solution is commonly an acid such as sulphuric acid, or cyanic acid. Leaching solutions are ^" generally expensive. ^'

Highly acidic leaching solution can pose an occupational health and environmental risk if it escapes from the heaps or storage ponds. Accordingly, it is necessary for heaps to be separated from the surrounding environment by barriers such as plastic sheeting and bunding. Dump leaching

Dump leaching combines characteristics of heap leaching and in-situ leaching. , Ore is dumped to allow processing similar to heap leaching, but the physical characteristics of the location allow for a valley or pit to act as the sump. Vat leaching

Vat leaching involves contacting crushed ore with leaching solution in large vats. Often the vats are equipped with agitators to maximise the solid to liquid contact. After vat leaching, the leached solids and pregnant solution are usually separated prior to- further processing. Metal recovery

Metal can subsequently be extracted from the pregnant leaching solution by various methods including electrolysis (electrowinning or electro-refining) or precipitation. Electrowinning and electro-refining respectively involve the recovery and purification of metals using electro-deposition of metals at a cathode, and either metal dissolution or a competing oxidation reaction at an anode. Precipitation involves the chemical precipitation of metals and their compounds or the contaminants from aqueous solutions.

One of the major problems associated with electrowinning is co-deposition or competing deposition of two or more metals at the cathode. Also, low value metals may be preferentially deposited as a result of their higher electrical activity as compared with the desired metal product. This can cause a significant drop in efficiency of the electrowinning process. Copper hydrometaUurgy

Copper is typically won from ores by heap leaching or dump leaching. Heap leaching is typically carried . out by placing ore on specially prepared lined leach pads Covering hundreds of hectares, and then spraying a weak acid solution on the surface of the heap. The acid solution percolates down through the pile of ore, becoming pregnant with copper. The pregnant copper solutions are collected from the base of the heap and pumped to a plant where the copper is removed from the aqueous acidic solution by organic solvent extraction. The extracted electrolyte solution is transferred to an electrowinning process where copper is plated out at a cathode.

In dump leaching, low-grade ores are piled directly onto hundreds of acres of native ground and subjected to percolation leaching over many years. The pregnant leach solution is typically collected in unlined natural drainage basins. Leaching of copper from dumps of sulphide ore principally relies on bacterial activity - the bacteria generating acid in situ for acid-consuming reactions, including oxygen reduction of the sulphide minerals and dissolution of the copper. Often the only solvent added is makeup water. Gold hydrometallurgy

Gold ores are also extracted by leaching. Dilute alkaline cyanide solutions are the most common leachants used, for gold dissolution, although chlorine media has been use in the past. Currently, chlorination is used in the treatment of matte, leach residues to recover the platinum group metals with gold as a by-product. Thiourea, thiosulphate, bromide and iodide solutions are potential alternatives to cyanide leaching, but none has yet been used commercially.

Cyanide leaching of gold forms part of the process of agitated leaching, heap or dump leaching, vat leaching, and intensive leaching. . Agitated leaching is used for ground slurries or reclaimed tailings and to recover the gold, the product is either subjected to solid-liquid separation or ^' treated in pulp with carbon or resin. The in pulp processes are sometimes incorporated into the leaching of mildly carbonaceous ores (the so-called carbon in leach and resin in leach).

Heap or dump leaching is used for run-of-mine or crushed gold ores from which the gold can be at least partially liberated without grinding.

Vat leaching is not commonly used because heap and agitated leaching provides better economies of scale. Vat leaching essentially consists of flooding a heap of ore contained within a vessel. It is used for leaching ores such as low grade oxide/free milling ores that do not respond well to heap or dump leaching and do not require grinding for gold liberation.

Intensive cyartidation leaching is often used commercially for treating gravity concentrates containing coarse gold, the leaching kinetics being optimised by careful control of cyanide and oxygen concentrations, temperature and pressure. Nickel hydrometaliurgy

One type of metal that is commonly won by leaching is nickel. Most nickel is mined from two types of deposits; (i) laterites consisting principally of Umonite (Fe, Ni)O(OH) and gamierite (a hydrous nickel silicate) (Ni, Mg) ₃ Si ₂ O ₅ (OH)/ and (ii) magmatic sulfide deposits consisting principally of pentlandite (Ni, Fe^Ss. The world's major nickel deposits are located in Russia, New Caledonia, Australia, Cuba and Indonesia. The deposits in Australia, Indonesia and New Caledonia are mainly laterites. Although the majority of the world's nickel deposits consist of laterite, the majority of nickel produced is derived from sulphide ore bodies. Laterites are surface geological formations that are formed by intensive and long lasting weathering of an underlying parent rock. Typically, weathering by rain water causes dissolution of primary rock minerals, including easily soluble metals such as sodium, potassium, calcium and magnesium. Less soluble elements such as iron and aluminium remain. Lateritisation of ultramafic igneous rocks (such as serpentinite, dυnite or peridotite) results in laterites that comprise a significant amount of nickel.

Laterites can range in consistency from soft and friable to firm and sufficiently physically resistant to be cut into blocks to be used as road or building blocks.

In the past, nickel has typically been removed from ores using pyrometallurgical techniques to produced matte for further refining. Recently, hydrometallurgical processing has been increasing, including acid leaching of nickel laterites.

Leaching laterite heaps differs from leaching of copper and gold heaps because the laterite heaps are constructed by creating agglomerates of the laterite soil. For copper and . gold, agglomerate formation is not always necessary because the minerals are incorporated in rocks and rock heaps are relatively stable. When copper and gold are leached only a small percentage of the heap mass is dissolved. For nickel laterite however, approximately 30 wt% of the heap mass dissolves. This means that nickel laterite heaps are more difficult to manage. Specifically, they are difficult to manage because agglomerates are structurally unstable and can form layers or regions of relatively impermeable material which controls the flow rate of the'leachant. Application of the leachant by surface irrigation often results in formation of preferential flow pathways. The leachant will continue to seek the path of least resistance and continues to flow along the same pathways. This makes it difficult to get a homogeneous spread of leachant through the heap and therefore nickel dissolution tends to be uneven, and ultimately incomplete or extremely slow.

As a result of the agglomeration process and possibly preferential flow contributions, laterite heaps leached with acid produce an initial high concentration flush of nickel followed by a long period of very low concentration output. Heaps are often run for as long as 2 years with the initial peak in output concentration lasting only weeks. Furthermore, preferential flow, heterogeneous flow, reprecipitation and agglomerate structural collapse all combine to create the potential for heap instability. Heap failure is also a safety concern, an environmental threat as well as a source of production inefficiency. Nickel is typically extracted from pregnant leaching solutions by an electrowinning process in which the nickel is electroplated onto a cathode. Electrowinning can also be used to process the "matte" extracted from the primary smelting treatment of nickel sulphide ores , World demand

The world has an insatiable desire for mined material to feed industrialisation and modernisation particularly in fast-developing nations such as China and India. Supply of metals, particularly base metals such as copper, nickel, zinc, lead and aluminium is barely keeping up with demand. The majority of raw metals are derived by mining as recycling rates for most metals are still very low. Mining is very capital and time-intensive and it is taking years to increase output sufficiently to satisfy market demand.

The demand for copper has been driven by growing consumption in China. In 2003 Chinese demand for copper was so high that it virtually exhausted the national stockpile, In 2005 its continued consumption caused remaining global stockpiles, to plummet to alarming levels.

In recent times there has also been an enormous world-wide acceleration in the exploitation of nickel laterite ores in anticipation of continued strong growth in primary nickel consumption. The current output of nickel derived from sulphide deposits is not expected to be sufficient to meet world demand in the future mainly because the sulphide deposits are being used up at a faster rate than they are being discovered. Accordingly, to guarantee the future supply of nickel, there needs to be greater emphasis on processing of laterite.

Even noble metals have experienced increasing demand with concomitant increased in value. However along with this, costs have risen precipitously and the failure of production to keep pace has led to diminution of world stockpiles of these metals. Bringing new mines into production is a capital and time-intensive process. For example, bringing a new large gold mine into production can take a decade or more and costs billions of dollars. It is more important than ever for producers to make more of their existing processes as this is the quickest way to increase production volumes and improve the economics of production.

There is, therefore, a need for a process of extraction of mined material that maximises the recovery of desired metal and its purity. In particular, there is a need for an extraction process that facilitates more, economical downstream processing. SUMMARY OF THE INVENTION

It has now been found that extraction of mined material can be significantly improved by the use of metal-binding particles to bind metals, particularly heavy metals, in liquid extracted from the mined material.

This includes extraction of fluid from mined material such as ores, sands, agglomerates and carboniferous deposits. The fluid extracted may be native or added to the mined material as part of the process.

Specifically, the present invention provides a process for extraction of mined material using the steps of: (a) draining liquid from the mined material, and (b) adding metal-binding particles to the drained liquid.

As used herein the term "particle" or "particulate" refers to a body having finite mass and internal structure but negligible dimensions. Typically a particle is an aggregation of sufficiently many atoms or molecules that it can be assigned macroscopic properties such as volume, density, pressure, and temperature. A particle may be in the form of a film, latex or sheet, The metal-binding particles may be are small, typically micro- or nano-sized.

The metal-binding affinity of specific types of particles can be used to target one or more metals. For example, the metal-binding particles can be used to selectively extract a target metal from the drained liquid. Alternatively, or in addition, metal-binding particles can be used to selectively remove problematic or low value contaminants. Removal of contaminants may significantly improve downstream processes such as electrowinning.

Affinity of metal-binding particles for specific metals can be optimised by adjusting parameters such as pH and temperature of the drained liquid. The metals targeted by the metal-binding particles may be any suitable metal, typically a transition metal. In a preferred embodiment the metal is a base metal, such as nickel, copper or zinc, Ih a further preferred embodiment the metal is a noble metal, such as gold.

In a particularly preferred embodiment the present invention provides a process for extraction of mined material using the steps of: (a) forming aheap of mined material, (b) applying a zero or negative fluid potential to the mined material, (c) draining liquid from the mined material, and (d) adding metal-binding particles to the drained liquid.

The 'heap' of mined material may take any convenient form. For example, the heap may consist of a collection of mined material confined in a mine pit or a man-made reservoir. Alternatively the mined material may be in the form of an unconfmed pile or beach.

The heap may consist entirely of mined material taken directly from the earth. Alternatively, the mined material in the heap may have been subjected to an initial process, such as an agglomeration step. The mined material in the heap may also have been physically or chemically separated from a larger quantity of mined material.

As the person skilled in the art will readily appreciate, the process of the present invention is suitable for removing fluid of various types from mined materials. The liquid drained from the mined material may be native fluid (typically water), or a fluid such as water or leachant solution that has been introduced to the mined material. The liquid may be drained by any convenient technique such as suction or gravity or combinations thereof.

The extracted fluid may contain a valuable metal such as gold or copper or nickel. It may also contain low value or problematic metals. Accordingly, in one embodiment, the present invention provides a process for extraction of metal from ore using the steps of: (a) forming an ore heap, (b) applying a zero or negative fluid potential to the ore heap, (c) drawing a leachant into the heap to wet the ore, (d) leaving the leachant in contact with the ore to create a solution pregnant ■ with metal, (e) draining the pregnant solution by applying suction to the ore, and (f) adding metal-binding particles to the drained pregnant solution. Preferably the leachant is drawn into the heap (and the pregnant solution is drawn out of the heap) in a manner that minimises or avoids creating of preferential flow pathways. In a particularly preferred embodiment of the invention the leachant is applied spatially through the heap to ensure even distribution.

Although the process of the present invention may be applied to any mined material, it is preferred that the mined material is an ore heap, particularly an ore heap comprising laterite, either agglomerated, or non-agglomerated. In a particularly preferred embodiment of the present invention the mined material is laterite. Specifically, in this embodiment the present invention provides a process for leaching metal from a laterite heap using the steps of: (a) forming a laterite heap, (b) applying a zero or negative fluid potential to the laterite heap, (c) drawing a leachant into the heap to wet the laterite, (d) leaving the leachant in contact with the laterite to create a solution pregnant with metal, (e) draining the pregnant solution by applying suction to the laterite, and (f) adding metal-binding particles to the drained pregnant solution.

When the process of the present invention includes the use of a leachant, the leachant may have any chemical composition suitable for dissolving the desired metal from the mined material. For example, in the case of nickel leaching the leachant will be a sulphuric acid solution, while in the case of gold leaching it will typically be a cyanide solution, The use of a zero or negative fluid potential overcomes many of the problems associated with leaching processes of the prior art by ensuring that leachant residence time is controlled as a function of dissolution time instead of heap geometry and fluid flow. Specifically, in other known processes, metal dissolution is affected by the time of contact between dissolvable minerals (assumed to be randomly distributed in the case of nickel leaching) and the leachant. Specifically, in the conventional approach, the leachant is added to the top of the heap and contact time is largely controlled by the residence time of the acid as it moves through the heap. This is, in turn, controlled by gravity and the permeability properties of the laterite.

By contrast the residence time can be controlled as a function of dissolution time by drawing the leachant into the mined material using the capillary suction of, which is achieved by applying a zero or negative fluid potential to the heap. Once the mined material has absorbed as much leachant as it can no more leachant is drawn into the heap, thus minimising the amount of acid used.

A significant advantage of using zero or negative fluid potential is that the mined material in the heap is evenly wet, avoiding the formation of preferential pathways of acid flow. Furthermore, the leachant remains in place until the extraction step is commenced. This means that the leachant can be left in contact with the ore as long as is required for the metal/leachant reaction thus maximising dissolution of the metal of interest from the mined material. This control avoids problems associated with reprecipitation of free flowing liquid with no remaining dissolution capacity. Furthermore, the concentration of dissolved metal in the pregnant solution is high and generally consistent over time, depending on the ore,

Extraction of the pregnant solution can be achieved by applying suction (tension) to the heap. The pregnant solution is thus drawn out of the pores inside the mined material.

The magnitude of the suction controls the minimum diameter of pores from which a liquid (such as the pregnant solution) can be extracted. The greater the suction, the smaller the pores from which the liquid will drain and without wishing to be bound by theory, it is believed that this can be expressed mathematically as follows: s = (2?vQS(ή/(pgr) =(l x 10 ^"5 )/r metres where s is tension and r is the equivalent circular pore radius.

Typically the smallest pores will not be emptied.

With reference to the leaching process, when fresh leachant is subsequently introduced the average distance between pores with fresh leachant and small pores with pregnant solution will be very short. Therefore, diffusion of metal and leachant in opposite directions will occur quickly. Also, over time the pores will gradually increase in diameter as the dissolution process progresses,

When the mined material used in the process of the present invention is laterite, the laterite may be agglomerated, or not agglomerated.. Unlike the processes of the prior art, the laterite does not need to be agglomerated because there is no need for large pore space to facilitate gravity flow of leachant. Indeed, with clever sizing of ore particles it is possible to enhance the process of the present invention by creating pores between micro- aggregates which will draw in acid. 'Advantages of the use of zero or negative fluid potential'

One of the advantages of using zero or negative fluid potential in the process of the present invention is that it reduces the quantity of leachant that needs to be used. For example, with reference to extraction of nickel from iaterite, the volume of acid consumed is dramatically reduced as compared to conventional processes and therefore provides considerable economic savings. Conventional acid leaching requires a large amount of acid to be passed down the heap under gravity, the quantity of acid passed through the π heap over time depending mostly on the ore permeability, heap height and rate of acid application. This results in consumption of large volumes of acid, low concentration of metals in the out flowing leachant, but a significant concentration of unreacted acid. However, if the process uses zero or negative fluid potential the acid added is only that which the heap takes up under suction. This volume is much small than the total pore volume in the heap (per unit volume of the heap) because the large pores between agglomerates are not filled with leachant. Secondly, the leachant is left in place to incubate until it has dissolved all the metal that it can before it is extracted. Thus the leachant is in a static state rather than flowing dynamically most of the time. Ideally, the pregnant solution will have little or no acid content.

By eliminating the free flow and free draining of acid, the present invention has a far lower risk of leachant escaping into the surrounding environment and a much reduced need for infrastructure under the heaps.

The use of zero or negative fluid potential also reduces the problems of heap instability. In the conventional process, the rapid addition of leachant to the top of an agglomerate heap combined with significant overburden pressure and liquid weight result in disaggregation of the agglomerates. This collapse creates low permeability zones or layers particularly at the bottom of the heap. Low permeability which is not matched to the leachant irrigation rate results in saturation excess at the base of the heap. Saturation excess greatly increases the risk of heap geotechnical failure. By contrast, the use of zero or negative fluid potential does not wet the agglomerates rapidly and therefore does not ^: cause their structural collapse. This avoids one cause of potential heap failure. Also, by avoiding the use of flowing acid, saturation excess cannot occur inside the heap. Thus risk of heap failure is much reduced as a result. ^' • .

The use of zero or negative fluid potential avoids problems of reprecipitation of unwanted and recalcitrant minerals. Few heaps match the flow path residence time with . the amount of time required to consume all the leachant. Therefore, in many cases leachant is recirculated because it is not all consumed, in the initial leaching run; This consumes energy. With specific reference to laterite heaps, this leads to secondary problems because of reprecipitation of secondary minerals as the solution is carried through the heap but there is no dissolution capacity. Reprecipitation can cause local cementation within the heap resulting in local internal ponding (saturation) which further enhances preferential pathways, inefficient acid distribution, and potentially regions of instability that possibly lead to heap collapse. Preferred composition of the particles

Preferably the particles for use in the process of the present invention are hydrogel particles, more preferably crosslinked hydrogel particles, which are capable of irreversible metal sequestering. They typically also have a capability for water storage or release. ^• The hydrogel material incorporates metal-binding ligands. Hydrogels are polymeric materials having a distinct three-dimensional structure and a high binding affinity for water. Traditional methods of synthesis include crosslinking copolymerization; crosslinking of reactive polymer precursors, and crosslinking via polymer-polymer reaction.

For example, the particles may comprise amide monomers (such as dimethyl acrylamide and bisacrylamide monomers or polydimethylacrylamide) copolymerised to from a polyacrylamide chains; the chain crosslinking may be carried put using any . suitable reaction such as emulsion polymerization. In particular, methods such as Reversible Addition Fragment chain Transfer polymerisation (RAFT) can be used to tailor the properties of the polymer. The RAFT process comprises performing polymerization in the presence of certain dithio agents such as xanthates or dithioesters. Tetra-thiols could also be used. The RAFT agent can be hydrolysed to form thiol ligands which are known to bind irreversibly to a wide range of metals.

The metal binding properties of these types of particles can be controlled by manipulation of the emulsion process: (i) particle size can be predetermined by changing the method of preparation (Mathur et al., 1996), (ii) water retention and mechanical properties can be manipulated by the incorporation of other less hydrophilic monomers (e.g. styrene, methyl acrylate, methyl methacrylate) or through changing the amount or identity of the crosslinker, and (iii) the metal binding capacity can be controlled by the incorporation of RAFT-agent (Bell et al., 2006), followed by hydrolysis to thiol end- group ligands. Cage ligands can be attached to bind to specific metals (Say et al., 2002a ₅ b; Bell et al., 2006).

The physical size of the particles may be controlled by their method of synthesis. Alternatively, the physical size of the particles can be reduced, for example to micro or nano size, by physical means such as a ball-mill. In a particularly preferred embodiment, the particles of the present invention are comprised of a polymer having a surface that comprises pendant sulphur-containing moieties Ml that are capable of binding a metal, particularly a heavy metal, to form a complex comprising the polymer and the metal. Typically the pendant moieties Ml may be selected from thioketones, thiocarbonates, dithiocarbonates, trithiocarbonates, thioesters, dithioates, thioates, oxythiocarbonyl and- thiocarbonyloxy derivatives, thiocarbamates, dithiocarbamates, sulphides, thiols, thioethers, disulphides, hydrogendisulphides, mono-or di-thioace ^' tals, mono- or dithiόhemiacetals, thioamides, thioimides, imidothioates, thioguanidines, dithioguanidines, thiocyanates, isothiocyanates, sulphur containing macrocycles and optionally substituted sulphur containing heterocycles.

The pendant moieties Ml may be present as part of a heterocyclic or carbocyclic ring. Suitable sulphur functional groups that are part of a cyclic system include cyclic thioketones, cyclic thiocarbonates, cyclic dithiocarbonates, cyclic trithiocarbonates, cyclic thiolacetone, cyclic dithiolacetones, cyclic thioates, cyclic sulphides, cyclic thioethers, cyclic disulphides, cyclic mono- or di-thioacetals, cyclic thioamides, cyclic thioimides, cyclic imidothioates, cyclic thioguanidines and cyclic dithioguanidines.

Suitably, the sulphur-containing moiety Ml may be present as a substiruent of a carbocyclic or heterocyclic ring.

In some embodiments, the sulphur-containing surface-pendant heavy metal binding moiety Ml is selected from Formula I:

wherein:

Ll is a linking group to the polymer;

U is absent or present and is oxygen, sulphur or - NR ^4' ;

V is absent or present and is selected from H, oxygen, sulphur or - NR ^4" ; and

C is absent or present and represents a carbon atom, provided that C is only absent when both U and V are sulphur or when V is hydrogen; R ^! and R ² are independently selected from hydrogen, cyano, halo, hydroxy, Ci-

6alkoxy, mercapto, amino, nitrile, nitro, nitroso, optionally substituted Ci-salkyl, optionally substituted Ci.galkenyl, optionally substituted C ₁ . galkynyl, optionally substituted Ci ₄ alkylaryl, and optionally substituted aryl; R ¹ and R ² combine with C to form C=S, C=N-RN, or C=O, wherein RN is hydrogen, hydroxy, amino, optionally substituted C _1-8 alkyl, optionally substituted Cμgalkenyl, optionally substituted C _1-8 alkynyl, optionally substituted C]. 4alkylaryl, and optionally substituted aryl; or R ^] and R ² combine to form an optionally substituted 1,3-dithiane or 1,3 dithiolane; R ³ is absent when V is. a hydrogen atom and is selected from hydrogen, optionally . substituted Cι. _% aϊkyl, optionally substituted C _2-8 alkenyl, optionally substituted C ₂ - 8alkynyl, optionally substituted C _M alkylaryl, optionally substituted heterocycloalkyl, optionally substituted heteroaryl and optionally substituted aryl; and R ⁴ is selected from hydrogen, hydroxy, amino, optionally substituted Chalky!, optionally substituted C _1-8 alkenyl, optionally substituted C _1-8 alkynyl, optionally substituted Cι- ₄ alkylaryl, and optionally substituted aryl; provided that at least one of U, V or the combination of R ¹ and R ² contains a sulphur atom. . • ^•

In some embodiments, the linking group Ll is of Formula II:

wherein:

W is absent or present and is selected from >NR ^G , -NHC(O)-, -C(O)NH-, -S-, or - 0-, wherein R ^G is hydrogen, optionally substituted Q-galkyl, optionally substituted arylCMalkyl, optionally substituted aryl or optionally substituted heteroaryl,-

AIk ¹ is absent or present and is selected from an optionally substituted divalent Cwalkyl, optionally substituted divalent C ₂ -salkenyl and optionally substituted divalent C _2- salkvnyl chain, optionally substituted divalent aryl, optionally substituted divalent heteroaryl, optionally substituted divalent Ci ^alkylaryl, and optionally substituted divalent arylC _M alkyl, with the proviso that both W and Q are not simultaneously present when AIk ¹ is absent;

AIk ² is absent or present and is selected from optionally substituted divalent C _1-6 alkyl, optionally substituted divalent C ₂ . ₅ alker.yl, optionally substituted divalent Ca^alkynyl chain, optionally substituted divalent aryl, optionally substituted divalent heteroaryl, optionally substituted divalent C _M alkylaryl, and optionally substituted divalent arylCwalkyl; Q is absent or present and is selected from -NH-, -0-, -S-, -NHC(O)-, -C(O)NH-, NHSO ₂ -, - C(R ^G )=N-N-, -NHC(O)NH-, -NHC(S)NH-, - C(R ^G )=N-, and - N=C(R ^G )-; and when all of Alk ¹ , Alk ² , W, and Q are absent, L ¹ is a covalent linkage.

In some embodiments, the pendant sulphur-containing moiety M ¹ is selected from:

R R wherein R ³ , R ⁴ , and R ^N are defined as above; R ⁵ is the same as R ³ ; and R ⁶ is selected from hydrogen, cyano, halo, hydroxy, C _1-6 alkoxy, C _1-6 acyloxy, mercapto, amino, nitrite, nitro, nitroso, optionally substituted C _1-8 alkyl, optionally substituted C _1-8 alkenyl, optionally substituted C _1-8 alkynyl, optionally substituted C _1-6 alkylaryl, and optionally substituted aryl

In specific embodiments, the sulphur-containing surface-pendant heavy metal binding moieties M ¹ are of formula IIa:

wherein:

L ¹ is as defined above;

S represent a sulphur atom; R ⁷ is selected from halo, C _1-6 alkyl, C _1-6 alkoxy, optionally substituted aryl, and optionally substituted Ci- ₄ alkylaryl.

In some embodiments, the polymer surface further comprises a carbonyl- containing moiety M ² .

The carbonyl-containing moiety M ² may be selected from ketones, di and tri- ketones, hydroxy-ketones, vinyl ketones, esters, keto-esters including β-ketoesters, aldehydes, carbonates, anhydrides, carbamates, amides, . imides (diacylamines), triacylamides, hydrazides, isocyanates and ureas.

The moiety M ² may be present in the form of a heterocyclic or carbocyclic ring system. Suitable, carbonyl functional groups that are part of a cyclic system include cyclic ketones, lactones, β-diketones, cyclic carbonates, cyclic carbamates, cyclic amides, cyclic diacyl amines, cyclic anhydrides,

Suitably, the carbonyl-containing moiety M ² may be present as a substituent of a carbocyclic or heterocyclic ring. ^•

In some embodiments the polymer surface comprises a sulphur-containing moiety M ¹ selected from a xanthate and a carbonyl-containing moiety M ² selected from a keto functionality.

In specific embodiments, the polymer surface comprises a sulphur containing M ¹ selected from a xanthate and a carbonyl-containing moiety M ² selected from a beta-keto ester.

In some embodiments, the polymer surface comprises one or more heavy metal- binding moieties M ¹ wherein at least one heavy metal binding moiety is selected from Formula III:

wherein:

X ₁ to Xe are independently selected from sulphur or - NH- provided that at ^" least one of Xi to X ₆ is a sulphur atom; and

L ¹ is defined as above.

In some embodiments, the polymer surface comprises a xanthate moiety, a keto functionality, and a moiety of formula III.

In further embodiments, the polymer surface comprises a xanthate moiety, a beta- keto ester functionality, and a moiety of formula III.

In still further embodiments, the polymer surface comprises a xanthate moiety, a beta-keto ester functionality, and a moiety of formula III wherein Xi, X ₃ and X5 are -NH- and X ₂ , X ₄ and Xg are sulphur, and L ¹ is an imine.

In some embodiments, the polymer surface comprises a xanthate functionality and a moiety of formula III.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, preferred methods and materials are described. For the purposes of the present invention, the following terms are defined below.

There is a diverse range of synthetic polymers known to those skilled in the art. The kind and structure of polymer synthesised depends on many factors including the kind and- number of monomers used, the polymerisation method, polymerisation conditions, and the various co-factors used at the beginning, during and at the end of the polymerisation process. Illustrative examples of types of polymers include: "homo- polymers" which refers to polymers comprised of macromolecules constructed of identical monomers; "chain polymers" a kind of homo-polymer which the repetition of units is linear- a chain polymer consists of macromolecular chains with identical bonding linkages to each monomer unit which may be represented as: -[A-A-A-A-A-A]-, wherein "A" represents a monomelic unit; "branched polymers" which are polymers comprised of macromolecules with one or more chemical side chains extending from the main backbone or chain of the macromolecule; "star-branching polymers" which are polymers comprised of branch macromolecules wherein the branches ultimately emanate from a single point; "dendrimers" which are branched macromolecules with a high degree of branching - typically the branches of these molecules have branches themselves; "block polymers" which are polymers comprised of macromolecules composed of two or more connected blocks - ^' in the simplest case, the XY diblock consists of two blocks, X and Y, joined together; "copolymers" which are polymers comprised of macromolecules derived from more than one species of monomer ~ polymers comprised of macromolecules having monomelic units differing in constitutional or configurational features ^' but derived from a single monomer, are not regarded as copolymers; "graft copolymers" which are polymer comprised of macromolecules with one or more species of block connected to the main chain as side chains. These side chains have constitutional or configurational features that differ from those in the main chain. In a graft copolymer, the distinguishing feature of the macromolecular side chains is constitutional, Le,, the side chains comprise units derived from at least one species of monomer different from those which supply the units of the main chain; "statistical copolymers" which are copolymers comprised of macromolecules in which the sequential distribution of the monomelic units obeys known statistical laws; e.g., the monomer sequence distribution may follow Markovian statistics of zeroth (Bernoullian), first, second, or a higher order; "random copolymers" which are special case of a statistical copolymers - it is a statistical copolymer comprised of macromolecules in which the probability of finding a given monomelic unit at any given site in the chain is independent of the nature of the neighbouring units at that position (Bernoullian distribution); "alternating copolymers" which are copolymers comprised of macromolecules further comprising two species of monomelic units distributed in alternating sequence, for example the arrangement -ABABABAB- or (AB) represents an alternating macromolecule; "periodic copolymers" which are copolymers comprising macromolecules where the monomelic units appear in an ordered sequence, for example - [ABC-ABC-ABC]-, wherein "A", "B" and "C" represent different monomelic units.

A "block copolymer" refers to a polymer comprised of macromolecules which are further comprised of at least two constitutional sequences; having any one of a number of different architectures, where the monomers are not incorporated into the macromolecule architecture in a solely statistical or uncontrolled manner. Although there may be three, four or more monomers in a single block-type macromolecule architecture, the polymer will still be referred to herein as a block copolymer. In some embodiments, the constitutional sequences of the block copolymer will have an A-B architecture (with "A" and "B" representing the). Other architectures included within the definition of block copolymer include A-B-A, A-B-A-B ₅ A-B-C, A-B-C-A, A- B-C-A-B ₅ A-B-C-B, A-B-A- C (with "C" representing a third monomer), and other combinations that will be obvious to those of skill in the art.

In addition, it is possible to prepare polymer blends. Polymer blends span the entire range from fully miscible to completely immiscible, The thermodynamic drive towards phase separation increases with increasing inherent incompatibility and as with increasing average molecular weights of polymer chains. Unlike, for example, block copolymers where highly ordered morphologies are found, one does not normally find ordered arrangements of regularly-shaped domains in a blend since the polymer chains of different blend components are not bonded to each other. The blend morphology can be affected significantly by many factors known to those skilled in the art.

Of particular importance is the surface functionalised nature of the polymers of the present invention. As used herein the term "surface functionalised" in relation to polymers, refers to a polymer, the surface of which has pendant functional groups, or has been functionalised to have pendant functional groups. As used herein the term "surface" when applied to a polymer, for example referring to the "polymer, surface" or "surface of a polymer", refers to the surface area of a polymeric material including any pores and channels that form a continuous part of the surface area, As used herein the term "functional group" refers to a chemical moiety, such as an atom or group of atoms, in an organic compound that gives the compound some of its characteristic properties. As used herein the term "surface functional groups" refers to the functional groups that are pendant from the polymer surface. As used herein a "pendant group", refers to a chemical offshoot, such as a functional group, that is neither oligomeric nor polymeric from a chain or backbone. As used herein the term "backbone" refers to the main structure of a polymer onto which substituents are attached. As used herein a "substituent" refers to a functional group on a molecule, As used herein a "substituent" when used in relation- to polymers, refers to a functional group such as a linker or a surface functional group on a macromolecule. Typically, a substituent, such as a functional group or linker, is substituted in place of a hydrogen atom on a parent chain. Surface functionalised polymers can be prepared in a variety of ways. By way of illustration, a polymer may have an appropriately functionalised surface resulting from the polymerisation process employed. For example, preparation of a styrene based polymer by the RAFT process using a xanthate control agent and styrene may provide a resulting ^' surface functionalised polymer (Y) by virtue of the xanthate end groups on individual macromolecules. As used herein the term "end group", refers to the chain-terminating functional group of a macromolecule. Further, reaction of the styrene polymer so formed with another monomer under the appropriate polymerisation conditions to form a block copolymer, can introduce a second functional group to the polymer. For example, use of 2-(acetoacetoxy)ethyl methacrylate (AAEMA) as the second monomer, will introduce a carbonyl functional groups to afford a di-functionalised polymer (Z) having both carbonyl and xanthate functions on its surface.

Alternatively, a prepared polymer such as polymer (Z) may have its surface suitably functionalised after the polymer has been synthesised. For example, the carbonyl functions can be reacted with primary amines derivatives to form imines (Schift base formation) thereby introducing further functionalisation to the polymer through a post , polymerisation surface modification. The amine derivative may be further desirably functionalised with heavy metal binding groups. As used herein the term "heavy metal binding group" refers to a functional group that binds heavy metals. According to the methods of the present invention, the heavy metal binding group is a sulphur-containing heavy metal binding group. By way of another illustrative example, polymer (Z) as described above can be hydrolysed in the presence of a secondary amine such as piperidine, to afford a polymer with thiol surface functionalisation. As used herein the term "surface functionalisation" when used in relation to a polymer surface, may variously refer to the functionalised surface of the polymer, the process of adding functional groups to the polymer surface, or modifying, functional groups present on the polymer surface, in order to obtain desired functional groups on the polymer surface.

Similarly, a polymer with halogen surface functionalisation such as bromo- functionalisation, can be reacted with a di- or tri-thiocarbonyl salt, to form a xanthate or trithiocarbonatesurface functionalised polymer. .

As used herein, the term as used alone or as part of a group such as "di(C _1-6 alkyl)amino", refers to straight chain, branched or cyclic alkyl groups having from 1 to 6 carbon atoms. Examples of such alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, cyclopentyl and cyclohexyl Similarly, CM, CJ _-8 and CM ₀ alkyl, for example, refer to groups having 1 to 4, 1 to 8, and 1 to 10 carbon atoms, respectively.

As used herein, the term "halo", as used alone or as part of a group such as "C _3- ehalo alkenyl", refers to fluoro, chloro, bromo and iodo groups.

The terms "C _1-6 alkoxy" and "C _1-6 alkyloxy" as used herein, refer to straight chain or branched alkoxy groups having from 1 to 6 carbon atoms. Examples of C _1-6 alkoxy include methoxy, ethoxy, n-propoxy, isopropoxy, cyclohexyloxy, and the different butoxy isomers. Similarly, Ci _-4 , Ci _-8 and CMO alkoxy refer to groups having 1 to 4, 1 to 8, and 1 to 10 carbon atoms, respectively. As used herein, the term "aryloxy" refers to an "aryl" group attached through an oxygen bridge. Examples of aryloxy substituents include phenoxy, biphenyloxy, naphthyloxy and the like.

The term "arylCwalkyloxy" as used herein, refers to an "arylCnalkyl" group attached through an oxygen bridge. Examples of "arylCmalkyloxy" groups are benzyloxy, phenethyloxy, naphthylmethyleneoxy, biphenylmethyleneoxy and the like.

The term "Ci.ioacyl" as used herein, refers to straight chain or branched, aromatic or aliphatic, saturated or unsaturated acyl groups having from 1 to 10 carbon atoms. Examples of Q-ioacyl include formyl, acetyl, propionyl, butanoyl, pentanoyl, pivaloyl, benzoyl and 2-phenylacetyl, Similarly, C _1-4 , Ci- ₆ and C _\ . _% acyl refer to groups having 1 to 4, 1 to 6, and 1 to 8 carbon atoms, respectively.

As used herein, the term group attached through a carbonyl group. Examples of "C _1-6 alkyloxycarbonyl" groups include methylformate, ethylformate, cyclopentylformate and the like.

The term "C _1-6 alkenyl" as used herein, refers to groups formed from C _2- g straight chain, branched or cyclic alkenes. Examples of Cϊ.salkenyl include allyl, 1-methylvinyl, butenyl, iso-butenyl, 3-methyl-2-butenyl, 1-pentenyl, cyclopentenyl, 1-methyl- cyclppentenyl, 1-hexenyl, 3-hexenyl, cyclohexenyl, 1,3-butadienyl, l -4,ρentadienyl, 1,3- cyclopentadienyl, 1,3-hexadienyl, .1,4-hexadienyl, 1,3-cyclohexadienyl and 1,4- cyclohexadienyl. Similarly, C _2-4 , C ₂ - ₆ and C ₂ - ₁₀ alkenyl, for example, refer to groups having 2 to 4, 2 to 6, and 2 to 10 carbon atoms, respectively.

As used herein, the term "Cj-βalkynyl" refers to groups formed from C ₂ - ₈ straight chain or branched groups as previously defined which contain a triple bond. Examples of .C ₂ -galkynyl include 2,3-propynyl and 2,3- or 3,4-butynyl. Similarly, C ₂ - ₄ , C _2-6 and C ₂ . ₁ 0 alkynyl, for example, refer to groups having 2 to 4, 2 to 6, and 2 to 10 carbon atoms, respectively.

As used herein, the term "arylCi-ialkyl" refers to. groups formed from CM straight chain, branched alkanes substituted with an aromatic ring. Examples of aryld. 4alkyl include methylphenyl (benzyl), ethylphenyl, propylphenyl and isopropylphenyl.

By "optionally substituted" it is meant that a group may include one or more

^' substituents that do not interfere with the heavy metal binding activity of the. compound of formula L In particular, they do not bind to metals that are not heavy metals such as sodium, potassium and calcium. In some instances, the substituent may be selected to improve certain physico-chemical properties of the polymer such as solubility in organic and aqueous media. Examples of optional substituents include halo, ^" Cmalkyl, C ₂ . ₄ alkenyl, C ₂ - ₄ alkyήyl, C ₁ . ₄ a.koxy, haloCi- ₄ alkyl, hydroxyC _1-6 alkyl, C]_ ₄ alkoxy. Cμγacyl, Ci _-7 acyloxy, hydroxy, aryl, amino, azido, nitro, nitroso, cyano, carbamoyl, trifluoromethyl, mercapto, C _M alkylamino, C _1-6 dialkylamino, aryloxy, formyl, carbamoyl, Ci- ₆ alkylsulphonyl, Ci-βarylsulphonyl, C _1-8 alkylsulphonamido, Ci- ₆ arylsulphonamido, C _{1- 4} alkylamino, di(Ci4alkyl)amino, - NR ¹⁰ R ¹¹ and C _1-6 alkoxycarbonyl.

As used herein, the term "arylthio" refers to an "aryl" group attached through a sulfur bridge, Examples of arylthio include phenylthio, naphthylthio and the like.

As used herein, the term "Ci-ioalkylthio" refers to straight chain or branched alkyl groups having from 1 to 10 carbon atoms attached through a sulfur bridge. Examples of Ci ₄ oalkoxy include methylthio ethylthio, n-propylthio, isopropylthio, cyclohexylthio, different butylthio isomers and the like. Similarly, CM, CW and C ₁ - _S alkylthio refer to groups having 1 to 4, 1 to 6, and 1 to 8 carbon atoms, respectively.

By the term "ionised" is meant completely or partially converted into ions.

As used herein, "carbocycle", "carbocyclic residue" or "carbocyclic group" refers to cycloalkyl, cycloalkenyl, or aryl groups as described herein, Examples of carbocycles include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, adamantyl, cyclooctyl, [3.3.0]bicyclooctane, [4.3.0]bicyelononane, [4.4.0]bicyclodecane (decalin), [2.2,2]bicyclooctane, fluorenyl, phenyl, naphthyl, indanyl, adamantyl, or tetrahydronaphthyl (tetralin). The carbocycle is optionally substituted with one or more substituents which may be the same or different, and are as defined herein.

The term "cycloalkyl" as used herein, refers to a non-aromatic mono- or multicyclic ring system of about 3 to about 10 carbon atoms, preferably of about 5 to about 10 carbon atoms. Preferred ring sizes of monocyclic ring systems include about 5 to about 6 ring atoms. The cycloalkyl is optionally substituted with one or more substituents which may be the same or different, and are as defined herein. Exemplary monocyclic cycloalkyl include cyclopentyl, cyclohexyl, cycloheptyl, and the like. Exemplary multicyclic cycloalkyl include 1 -decalin, norbornyl, adamant-(l - or 2-)yl, and the like.

As used herein "cycloalkenyl" refers to a non-aromatic mono- or multicyclic ring system of about 3 to about 10 carbon atoms, preferably of about 5 to about 10 carbon atoms, and which contains at least one carbon-carbon double bond. Preferred ring sizes monocyclic ring systems include about 5 to about 6 ring atoms. The cycloalkenyl is optionally substituted with one or more substituents which may be" the same or different, and are as defined herein. Exemplary monocyclic cycloalkenyl include cyclopentenyl, cyclohexenyl, cycloheptenyl, and the like.

. The term "heterocycle" or "heterocyclic system" as used herein, refers to a heterocyclyl, heterocyclenyl, or heteroaryl groups as described herein, which consists of carbon atoms and at least one heteroatoms independently selected from the group consisting of N, O and S and including any bicyclic group in which any of the above- defined heterocyclic rings is fused to a benzene ring. The heterocyclic ring may be attached to its pendant group at any heteroatom or carbon atom which results in a stable structure. The heterocyclic rings described herein may be substituted on carbon or on a nitrogen atom if the resulting compound is stable. If specifically noted, a nitrogen in the heterocycle may optionally be quaternized. Examples of heterocycles include, but are not limited to, lH-indazole, 2-pyrrolidonyl, 2H,6H-l ,5,2-dithiazinyl,.2H-pyrrolyl, 3H-indolyl, . 4-piperidonyl, 4aH-carbazole, 4H-quinolizinyl, 6H-l ,2,5-thiadiazinyl, acridinyl, azocinyl, benzimidazolyl, benzofuranyl, benzothioruranyl, benzothiophenyl, benzoxazolyl, benzthiazolyl, benztriazolyl, benztetrazolyl, benzisoxazolyl, benzisothiazolyl, benzimidazalonyl, carbazolyl, 4aH-carbazolyl, b-carbolinyl, chromanyl, chromenyl, cinnolinyl, decahydroquinolinyl,. 2H,6H-l ,5,2-dithiazinyl, dihydrofuro

[2,3~b]tetrahydrofuran, furanyl, furazanyl, imidazolidinyl, imidazolinyl, imidazolyl, l H-indazolyl, indolenyl, indolinyl, indolizinyl, indolyl, isobenzofuranyl, isochromanyl, isoindazolyl, isoindolinyl, isoindolyl, isoquinolinyl, isothiazolyl, isoxazolyl, morpholinyl, naphthyridinyl, octahydroisoquinolinyl, oxadiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, oxazolidinyl., oxazolyl, oxazolidinylperimidinyl, phenanthridinyl, phenanthroHnyl, phenarsazinyl, phenazinyl, phenothiazinyl, phenoxathiinyl, phenoxazinyl, phthalazinyl, piperazinyl, piperidinyl, pteridinyl, piperidonyl, 4-piperidonyl, pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolidinyl, pyrazolinyl, pyrazolyl, pyridazinylj pyridooxazole, pyridoimidazole, pyridothiazole, • pyridinyl, pyridyl, pyrimidinyl, pyrrolidinyl, pyrrolinyl, pyrrolyl, quinazolinyl, quinolinyl, 4H-quinolizinyl, quinoxaliήyl, quinuclidinyl, carbolinyl, tetrahydrofuranyl, tetrahydroisoquinolinyl, tetrahydroquinolinyl, 6H-l ,2,5-thiadiazinyl, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, 1,3,4-thiadiazolyl, thianthrenyl, thiazolyl, thienyl, thienothiazolyl, thienooxazolyl, thienoimidazolyl, thiophenyl, triazinyl, 1,2,3-triazolyl, 1,2,4-triazolyl, 1,2,5-triazolyl, 1,3,4-triazolyl, xanthenyl. Preferred heterocycles include, but are not limited to, pyridinyl, furanyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, indolyl, benzimidazolyl, l H-indazolyl, oxazolidinyl, benzotriazolyl, benzisoxazolyl, oxindolyl, benzoxazolinyl, or isatinoyl. Also included are fused ring and spiro compounds containing, for example, the above heterocycles.

As used herein "heterocycloalkyl" refers to a non-aromatic saturated monocyclic or multicyclic ring system of about 3 to about 10 carbon atoms, preferably about 4 to about 8 carbon atoms, in which one or more of the carbon atoms in the ring system is/are hetero element(s) other than carbon, for example nitrogen, oxygen or sulfur. Preferred ring sizes of rings of the ring system include about 5 to about 6 ring atoms. The designation of the aza, oxa or thia as a prefix before heterocyclyl define that at least a nitrogen, oxygen or sulfur atom is present respectively as a ring atom. The h,eterocyclyl may be optionally substituted by one or more substituents which may be the same or different, and are as defined herein.

As used herein, the term "aryl" refers to optionally substituted monocyclic, bicyclic, and biaryl cafbocycltc aromatic groups, of 6 to 14 carbon atoms, covalently attached at any ring position capable of forming a stable covalent bond, certain preferred points of attachment being apparent to those skilled in the art. Examples of monocyclic aromatic groups include phenyl, toluyl, xylyl and the like, each of which may be optionally substituted with Cμ6acyl, Ct-βalkyl, Ci-βalkoxy, C ₂ - ₆ alkenyl, C _∑ ^alkynyl, Ci.galkylsulphonyl, arylsulphonyl, C _1-6 alkylsulphonamido, arylsulphonamido, halo, hydroxy, mercapto, trifiuoromethyl, carbamoyl, amino, azido, nitro, cyano, Ci- ealkylamino or di(C].§alkyl)amino. Examples of bicyclic aromatic groups include 1- naphthyl, 2-naphthyl, indenyl and the like, each of which may be optionally substituted with Cj-sacyl, Cj-ealkyl, Ci-βalkoxy, C ₂ -6alkenyl, Cϊ-ealkynyl, C _1-6 alkylsulphonyl, arylsulphonyl, C _1-6 alkylsulphonamido, arylsulphonamido, halo, hydroxy, mercapto, trifluoromethyl, carbamoyl, amino, azido, nitro, cyano, G^alkylamino or di(Ci, ealkyl)amino. Examples of biaryl aromatic groups include biphenyl, fluorenyl and the like, each of which may be optionally substituted with C _1-8 alkyl, C ₂ . βalkenyl, Q2.6alkynyl, Ci-βalkylsulphonyl, arylsulphonyl, Ci-βalkylsulphonamido, arylsulphonamido, halo, hydroxy, mercapto, trifluoromethyl, carbamoyl, amino, azido, nitro, cyano, Ci-ealkylamino or di(C _1-6 alkyl)amino. By the term "heteroaryl" is meant a monocyclic aromatic hydrocarbon group having 5 to 6 ring atoms, or a bi cyclic aromatic group having 8 to 10 atoms, containing at least one nitrogen, sulphur or oxygen atom, in which a carbon or nitrogen atom is the point of attachment. The designation of the aza, oxa or thia as a prefix before heteroaryl define that at least a nitrogen, oxygen or sulfur atom is present respectively as a ring atom. The rings or ring systems generally include 1 to 9 carbon atoms in addition to the heteroatom(s) and may be aromatic or pseudoaromatic. Examples of 5-membered "heteroaryl" groups include pyrrolyl, furyl, thienyl, pyrόlidinyl, imidazolyl, oxazolyl, triazolyl, tetrazolyl, thiazolyl, isoxazolyl, isothiazolyl, pyrazolyl, oxadiazolyl, thiadiazolyl and examples of 6-membered monocyclic nitrogen containing heterocycles include pyridinyl, pyrimidinyl, pyridazinyl, pyrazinyl and triazinyl, piperadinyl, piperazinyl, . morpholinyl, each of which may be optionally substituted with Cj-gacyl, C ₁ , (salkoxy, Ca^alkenyl, Ca-βalkynyl, d-galkylsulphonyl, arylsulphonyl, C ₁ . δalkylsulphonamido, arylsulphonamido, halo, hydroxy, mercapto, triflupromethyl, carbamoyl, amino, azido, nitro, cyano, Q-galkylamino or di(Ci. ₆ alkyl)amino. Examples of 9- and 10-membered nitrogen containing bicyclic heterocycles include indolyl, benzoxazolyl, benzothiazolyl, benzisoxazolyl, benzisothiazolyl, indazolyl, benzimidazolyl, purinyl, pteridinyl, indolizinyl, isoquinolyl, isoquinolinyl, quinolinyl, quinoxalinyl, cimiolinyl, phthalazinyl, quinazolinyl, benzotriazinyl and the like, each of which may. be optionally substituted with one or more Ci-βacyl, C _h alky., Ci-βalkoxy, C ₂ . βalkenyl, C ₂ - ₆ alkynyl, C _1-8 alkylsulphonyl, Ci-sarylsulphonyl, Ci-βalkylsulphonamido, Ci- . earylsulphonamido, halo, hydroxy, mercapto, trifluoromethyl, carbamoyl, amino, azido, nitro, cyano, or di(C _1-6 alkyl)amino. Examples of preferred heteroaryl groups include (optionally substituted) imidazoles, isoxazoles, isothiazoles, 1,3,4-oxadiazoles, 1,3,4-thiadiazoles, 1,2,4-oxadiazoles, 1,2,4-thiadiazoles, oxazoles, thiazoles, pyridines, pyridazines, pyrimidines, pyrazines, 1,2,4-triazines, 1,3,5-triazines, benzoxazoles, benzothiazoles, benzisoxazoles,. benzisothiazoles, quinolines and quinoxalines.

As used herein, the term "heteroarylC _1-6 alkyl", refers to a heteroaryl ring as described hereinabove, bonded through a "Ci- ₄ alkyl" group.

The term "sulphur-containing heterocycle" as used herein refers to mono or bicyclic rings or ring systems which include at least one sulphur atom and optionally one or more further heteroatoms selected from N, S and O. The rings or ring systems generally include 1 to 9 carbon atoms in addition to the heteroatom(s) and may be saturated, unsaturated, aromatic or pseudoaromatic,

Examples of 5-membered monocyclic sulphur containing heterocycles include thiophenes, thiazoles, tetrahydrothiophenes, thiazolidines, thiazolines, isothiazoles, thiadiazoles, oxathiolanes, and dithiolanes each of which may be optionally substituted with Cμealkyl, halo, hydroxy, mercapto, trifluoromethyl, amino, cyano or mono or di(C _1-6 alkyl) amino, Examples of 6-membered monocyclic sulphur containing heterocycles include optionally substituted dithianes, thiadiazines, dithiazines, and tetrahydrothiopyrans, each of which may be optionally substituted with Q^alkyl, Q^alkoxy, C ₃ .$alkynyl, C ₃ ^alkynyl, halo, hydroxy, mercapto, trifluoromethyl, amino, cyano or mono or di(Ci. ₆ alkyl) amino. Examples of 9- and 10- membered monocyclic sulphur containing heterocycles include benzothiazoles, benzisothiazoles, benzothiophenes, thiophthalans, benzooxathianes, thioisochromans, thiochromenes, thiochromans each of which may be optionally substituted with C _1-6 alkyl, d^alkoxy, Ca^alkynyl, Cs-βalkynyl, halo, hydroxy, mercapto, trifluoromethyl, amino, cyano or mono or di(Ci.6alkyl) amino. Other examples of sulphur containing heterocyclic, rings include thieno heterocycles, thienopyrimidines, thienopyridines, thienotriazines, thienoimidazotriazines, thienothiophenes, tetrahydrothioenothiophenes, ^' dithiophenes, thienofurans, thiaheterocycleny rings, including dihydrothiophenyl and dihydrothiopyrans, thiomorpholines, thiazolidines, and [2,1-bjthiazolines.

The term group attached through an amine bridge. Examples of "Ci-ealkylamino" include methylamino, ethylamino, butylamino and the like.

As used herein, the term "d.(C _1-6 alkyl)amino" refers to two "C _h alky." groups having the indicated number of carbon atoms attached through an amine bridge. Examples of "diζCi-βalkylJamino" include diethylamino, N-propyl-N-hexylamino, N- cyclopentyl-N-propylamino and the like.

The term "Cuoacylamino" as. used herein, refers to a "Cj.joacyl" group wherein the. "Ci.ioacyl" group is in turn attached through the nitrogen atom of an amino group. The nitrogen atom may itself be. substituted with a or "aryl" group. Examples of a "Cj-ioacylamino" include hexykarbonylamino, cyclopentylcarbonyl-amino(methyl), benzamido, 4-chlorobenzamido acetamido, propylcarbonylamino, 2-chloroacetamidb, methylcarbonylamino(phenyl), biphenylcarbonylamino, naphthylcarbonylamino and the like..

The term "- 1SR ¹⁰ R ¹¹ " as used herein, refers to a substituted amino function wherein R ¹⁰ and R ^u are independently selected from hydrogen, optionally substituted C _1- loacyl, optionally substituted Cμioacyloxy, optionally substituted heterocycloalkyl, optionally substituted heteroaryl, optionally substituted aryl, optionally substituted arylC _1-6 alkyl, and optionally substituted Ci-ioalkyl,

By "saturated" is meant a lack of double and triple bonds between atoms of a radical group such as ethyl, cyclohexyl, pyrrolidinyl, and the like.

By "unsaturated" is meant the presence one or more double and triple bonds between atoms of a radical group such as vinyl, acetylenyl, oxazolinyl, cyclohexenyl, acetyl and the like.

Conventionally, the word "polymer" used as a noun is ambiguous; it is commonly employed to refer to both polymer substances and polymer molecules. As used herein, "macromolecule" is used for individual molecules and "polymer" is used to denote a substance composed of macromolecules. The term "polymer" may also be employed unambiguously as an adjective, according to accepted usage, e.g. "polymer blend", "polymer molecule". As used herein a "macromolecule", is a molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of relatively low molecular mass. As used herein a "constitutional unit", refers to an atom or group of atoms (with pendant atoms or groups of atoms, if any) comprising a part of the essential structure of a macromolecule, a block or a chain, As used herein a "block", refers to a portion of a macromolecule, comprising many constitutional units, which has at least one feature that is not present in the adjacent portions. As used herein a "chain", refers to the whole or part of a macromolecule or block comprising a linear or branched sequence of constitutional units between two boundary constitutional units, each of which may be either an end-group or a branch point or an otherwise-designated characteristic feature of the macromolecule. As used herein a "constitutional sequence", refers to the whole or part of a chain comprising one or more species of the constitutional unit(s) in a defined sequence.

As used herein the terms such as "bind," "binding," "interact," "interacting" and the like refer to a physical association between two or more molecules, wherein the association may involve the formation of an induced magnetic field or paramagnetic field, covalent bond formation, an ionic interaction such as occurs in an ionic lattice, a hydrogen bond or alternatively, a van der Waals interaction such as a dipole-dipole interaction, dipole-induced dipole interaction, induced dipole-induced dipole interaction or a repulsive interaction or any combination of the above forces of attraction.. In some embodiments, these terms refer to the capacity to attract and hold something. In illustrative examples, the methods of the present invention have application in metal catalysed organic reactions from solid supports, or metal binding of antibodies or proteins to nanoparticle surfaces. In other embodiments, the methods of the present invention have application in the selective remediation of heavy metals from the human blood system, which has the potential to reduce symptoms caused by the deleterious effects of such heavy metals.

As used herein the term "solid support" refers to an insoluble, functionalised, polymeric material. A suitably derivatised solid support can be "surface functionalised" to contain functional groups to which metal ions can bind, often via a linker,. allowing them to be readily separated from solvents.

As used herein the term "linker" refers to a bifunctional chemical moiety attaching a functional group, such as a ligand, to a solid support.

It is evident to those skilled in the art that selected functional groups of the present invention may exist as resonance hybrids such as the following for the xanthate group: There are a diverse range of methods for the preparation of polymers known to those

skilled in the art. The following descriptions of polymerisation methods and mechanisms are intended to illustrate specific embodiments, and they are not intended to preclude any other polymerisation mechanism recognised by those skilled in the art. Illustrative examples of polymerisation methods include: "addition polymerisation" which refers to a process whereby the monomer molecules bond to each other without the loss of any other atoms - alkene monomers are the biggest groups of polymers in this class; "chain polymerisation" which refers to a chain reaction in which the growth of a polymer chain proceeds exclusively by reaction(s) between monomer(s) and reactive site(s) on the polymer chain, with regeneration of the reactive site(s) at the end of each growth step; "free radical polymerisation" which refers to refers to the synthesis of a polymer involving the chain reaction of free radicals with monomers; "condensation polymerisation" which refers to a process whereby usually two different, monomer combine with the loss of a small molecule, usually water; and "star-branching" which refers to a type of polymerisation in which a branched polymer is formed as branches emanating from a single point.

As defined herein,, the term "living polymerisation." refers to chain growth polymerisations proceeding in the absence of negligible chain breaking terminations.

As used herein a "monodisperse system" refers to a polymer system in which there is a relatively low distribution of molecular weights present. As used herein a "polydisperse polymer system" refers to a polymer system in which there is a relatively high distribution of molecular weights present.

Unless otherwise specified, polydispersity index or PDl refers to the ratio of mean/median for a distribution, or more specifically for the case of molecular weight measurements, polydispersity index is known in the art as Mw/Mn, where Mw is the weight average molecular weight and Mn is the number average molecular weight of a polymer sample. Values of PDI in this specification range from 1.0 and higher, with values near 1.0 representing relatively monodisperse samples.

The term "living polymerisation" was first coined in 1956 (Szwarc) to describe anionic polymerisation that proceeds without the occurrence of irreversible chain- breaking processes, such as chain transfer and termination. Such polymerisation provides strict control of the polymer end groups and allows synthesis of block co-polymers via sequential polymerisation of two or more monomers. Living polymerisation may include: slow initiation, reversible formation of species with various activities and lifetimes, reversible formation of inactive (dormant) species (reversible deactivation), and in some cases reversible transfer.

To distinguish between these processes and "living" polymerisation as defined by Szwarc, terms such as "controlled", "pseudo-living", "quasi-living" and "controlled/living" polymerisation have been introduced. As used herein, the term "controlled" describes all polymerisation processes ^' from which polymers with predetermined molar masses and low polydispersities can be obtained. The main criterion for living free-radical polymerisation behaviour is that experimental conditions must be selected to ensure that radical-radical termination and other side reactions (e.g, transfer to monomer, polymer, solvent etc) is negligible. Controlled polymerisation is a synthetic method to prepare polymers which are well-defined with respect to: topology (e.g., linear, star-shaped, comb-shaped, dendritic, cyclic), terminal functionality, composition and arrangement of co-monomers (e.g., statistical, periodic, block, graft, gradient), and have molecular weights predetermined by the ratio of concentrations of reacted monomer to introduced initiator. Controlled polymerisation may include transfer and termination but at a proportion low enough not to significantly affect the control of molecular properties as stated above. This means the • rate of these side reactions should be low enough in comparison with propagation rate to reach a given synthetic goal, hi addition: the time of mixing reagents should be short compared to the half-life of the polymerisation, the rate of initiation should be at least comparable to that of propagation, the rate of exchange between various active species should be faster than that of propagation of the fastest species, and the rate of de- propagation should be low in comparison to that of propagation. Controlled polymerisations are living if irreversible transfer and termination is below the detection limit using currently available instrumentation.

The following descriptions of polymerisation methods and mechanisms are intended to illustrate specific embodiments, and they are not intended to preclude any other polymerisation mechanism recognised by those skilled in the art.

Controlled radical polymerisation includes techniques such as atom transfer radical polymerisation (ATRP), nitroxide-mediated radical polymerisation (NMP),. degenerative transfer (DT) and reversible addition-fragmentation chain transfer polymerisation (RAFT).

In degenerative transfer, controlled polymerisation occurs via direct exchange of an atom or group between propagating macroradical chains. The control agent, which typically is an organyl halide with labile C-X bonds provides the atom or group necessary for DT.

In polymerisation by reversible addition-fragmentation transfer, an initiator produces a free radical that subsequently reacts with a polymerisable monomer. Polymerisation occurs via rapid chain transfer between growing polymer radicals and dormant polymer chains. The monomer radical reacts with other monomers and propagates to form a chain, which can react with a control agent, such as a dithioester. After initiation, the control agent becomes part of the dormant polymer chain. The control , agent can fragment, either forming R*, which will react with another monomer that will form a new chain or which will continue to propagate. In theory, propagation will continue until no more monomer is left and a termination step occurs. After the first polymerisation has finished, in particular circumstances, a second monomer can be added to the system to form a block copolymer. Such a technique can also be used to synthesise multiblock, graft, star, and end-functional polymers. nitiation

_R / gation

Atom transfer radical polymerisation (ATRP) is a catalysed, reversible redox process that achieves controlled polymerisation via facile transfer of labile radicals between growing polymer chains and a control agent. Normally, the labile radical is a halogen atom and the control agent is a metal/ligand combination that is stable in two different oxidation states. Chain polymerisation can be initiated in two ways, "direct ATRP" and "reverse ATRP".

Controlled polymerisation requires the presence of an agent to control the course of polymerisation while minimising undesirable side reactions, such as chain termination. These agents are called "control agents", and their characteristics depend greatly on the details of the polymerisation, including the mechanism for polymerisation, the types of monomers being used, the type of initiation, the solvent system, and the reaction, conditions. Many different types of control agents have been investigated.

A common feature of controlled free radical polymerisations is the use of a control agent to introduce reaction pathways for reversible formation of dormant polymer chains from growing macroradicals. Under typical conditions, the equilibrium position of the reversible reaction is shifted strongly toward the dormant species, which lowers the concentration of macroradicals to the point where the rate of termination by bimolecular reactions (for example, radical combination) is negligible compared to the rate of propagation. Controlled polymerisation by ATRP, RAFT, NMP and DT. have been studied extensively, and detailed mechanisms have been proposed for these systems. In other cases, reaction mechanisms are not well established, but it is clear that addition of specific reagents facilitates reversible formation of stable free radicals and leads to behaviour characteristic of controlled free radical polymerisation.

AU polymerisation reactions must be initiated. For some monomers, such as styrene, for example, thermal self-initiation can occur without the need for additional reagents. For many other monomers, initiation may be accomplished by adding an agent to trigger one or more chemical reactions that ultimately produces an intermediate capable of propagating polymerisation. These agents often are referred to as "initiators". The type of initiators suitable for the present invention depend greatly on the details of the polymerisation, including the mechanism for polymerisation, the types of monomers being used, the type of control agent, the solvent system and the reaction conditions. Many different types of initiators have been investigated. As defined herein "initiation reaction" refers to the first step in chain polymerisation. Initiation involves the formation of a free radical. As defined herein a "free radical" is a molecule with . an unpaired electron, making it highly reactive. As defined herein an "initiator" is a molecule that decomposes into a free radical and used to "initiate" a polymer growth reaction.

The initiator may be an initiator for polymerisation by a free radical mechanism, such as ATRP • and RAFT or a related mechanism involving stable free radicals. Typically, suitable initiators for free radical polymerisation are reagents or combinations of reagents that are capable of producing free radicals. Other methods for producing free radicals, including exposure to ionising radiation (electron beam, X-ray radiation, gamma- ray radiation, and the like), photochemical reactions, and sonication, will be evident to those of skill in the art as suitable methods for initiating free radical polymerisation.

The addition of optional promoters or inhibitors may provide practical, advantages, including for example better control over initiation, more favourable reaction times, extended catalyst lifetimes and enhanced selectivity. The addition of other optional substances, including for example buffering ingredients, co-surfactants and antifreeze, may offer further advantages. As used herein the term "promoter" refers to a substance that, when added in relatively small amounts to a polymerisation system, imparts greater activity, improved selectivity or better stability. As used herein the term "inhibitor" refers to a substance that, when added in relatively small amounts to a polymerisation system, leads to decreased activity. Surfactants may be essential for preparation of polymers. Suitable surfactants include any compound or mixture of compounds capable of stabilising colloidal aqueous emulsions. Generally, surfactants are amphiphilic molecules that reduce the surface tension of liquids, or reduce interfacial tension between two liquids or a liquid and a solid. Surfactants may be small molecules or polymers, micelle-forming or non-micelle- forming, and may be anionic, cationic, zwitterionic or non-ionic.

Monomers that may be polymerised using the foregoing methods include at least one monomer selected from the group consisting of styrene, substituted styrene, alkyl acrylate, substituted alkyl acrylate, alkyl methacrylate, substituted alkyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacryl amide, N-alkylacrylamide, N-alkylmethacrylamide, N ₅ N-dialkylacrylamide, N, N-dialkylrnethacrylamide, isoprene, 1,3 -butadiene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, oxidants, lactones, lactams, cyclic anhydrides, cyclic siloxanes and combinations thereof. Functionalized versions of these monomers may also be used. Specific monomers or comonomers that may be used in this invention include methyl methacrylate, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers), 2-ethylhexyl methacrylate, isobornyl methacrylate, methacrylic acid, benzyl methacrylate, phenyl methacrylate, methacrylonitrile, a-methylstyrene, methyl acrylate, ethyl acrylate, propyl acrylate (all isomers), butyl acrylate (all isomers), 2-ethylhexyl acrylate, isobornyl acrylate, acrylic acid, benzyl acrylate, phenyl acrylate, acrylonitrile, styrene, glycidyl methacrylate, 2- hydroxyethyl methacrylate, hydroxypropyl methacrylate (all isomers), hydroxybutyl methacrylate (all isomers), N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, triethyleneglycol methacrylate, itaconic anhydride, itaconic acid, glycidyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate (all isomers), hydroxybutyl acrylate (all isomers), N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, triethyleneglycol acrylate, methacryl amide, N-methylacrylamide, N, N-dimethylacrylamide, N-tert-butylmethacrylamide, N-n-butylmethacrylamide, N-methylolmethacrylamide, N-ethylolmethacrylamide, N-tert-butylacrylamide, N-n-butylacrylamide, N-methylolacrylamide, N- ethylolacrylamide, vinyl benzoic acid (all isomers), diethylaminostyrene (all isomers), a-methylvinyl benzoic acid (all isomers), diethylamino alpha-methylstyrene (all isomers), p- inylbenzene sulfonic acid, p-vinylbenzene sulfonic sodium salt, trimethoxysilylpropyl methacrylate, triethoxysilylpropyl methacrylate, tributoxysilylpropyl methacrylate, dimethoxymethylsilylpropyl methacrylate, diethoxymethylsilylpropyl methacrylate, dibutoxymethylsilylpropyl methacrylate, diisopropoxymethylsilylpropyl methacrylate, dimethoxysilylpropyl methacrylate, diethoxysilylpropyl methacrylate, dibutoxysilylpropyl methacrylate, diisopropoxysilylpropyl methacrylate, trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, tributoxysilylpropyl acrylate, dimethoxymethylsilylpropyl acrylate, diethoxymethylsilylpropyl acrylate, dibutoxymethylsilylpropyl acrylate, diisopropoxymethylsilylpropyl acrylate, dimethoxysilylpropyl acrylate, diethoxysilylpropyl acrylate, dibutoxysilylpropyl acrylate, diisopropoxysilylpropyl acrylate, maleic anhydride, N-phenylmaleimide, N- butylmaleirύide, chloroprene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, 2- (2-oxo-l-imidazolidinyl) ethyl 2-methyI-2~propenoate, l -[2-[2~hydroxy-3- (2- propyl) propyl] amino] ethyl] - 2-imidazolidinone, N-vinyl pyrrolidone, N-vinyl imidazole, crotonic acid, vinyl sulfonic acid, and combinations thereof.

One group of polymer precursors are acrylate monomers, which are esters which contain vinyl groups. An example of a acrylate monomer is 2-(acetoacetoxy)ethyl methacrylate. Acrylate monomers are use to synthesise acrylates which are a type of vinyl polymer. Some acrylates have an extra methyl group attached to the alpha carbon, and these are called methacrylates. One of the most common methacrylate polymers is poly(methyl methacrylate).

The polymerisation systems described in this invention are combinations or mixtures of components, which include water, surfactant, control agent and at least one monomer.

In the preparation of polymers for uses in the methods of the present invention, control agent, initiator, promoter and inhibitor may be present in either or both solutions before mixing, or they may be generated in-situ during emulsificatioα, or they may be added after emulsification. The polymerisation system is subjected to polymerisation conditions to effect polymerisation of at least one monomer. For random copolymers or higher order inter-polymers, two or more monomers may be added to the polymerisation system at the same time. For block copolymers, the monomers are typically added in a desired sequence in order to grow the desired block. For the emulsion polymerisation systems, the polymerisation system is considered to be the starting components, which are subjected to the polymerisation conditions. The products of such polymerisation systems are the emulsions themselves or the polymers, after isolation or drying. The ratios of components (e.g., initiators, surfactants, monomers, control agents, etc. ) in the polymerisation system may be important and can vary widely depending on the particular embodiment being practiced. The ratio of monomer to control agent can beused to determine the molecular weight of polymers produced using the controlled emulsion polymerisation processes of this invention. According to these processes, the number average molecular weight of the resulting polymers depends linearly on the number of polymer chains in the polymerisation and the mass of monomer. Assuming every growing chain contains one residue derived from the control agent, the selection of a monomer to control agent ratio provides an opportunity to control in advance the polymer molecular weight (or degree of polymerisation). Typically, however, the actual molecular weight differs from the predicted molecular weight by a relatively constant percentage, and this difference should be taken into account when targeting a product with a desired molecular weight.

Another ratio that may be important is the ratio of equivalents of initiator to control agent. For many controlled polymerisations, including for example ROMP, NMP, cationic and anionic polymerisation, the number of polymer chains initiated should equal, in principle, the number of control agent molecules. For controlled polymerisation via transfer mechanisms, including for example RAFT, DT and ATRP, only catalytic amounts of initiator are required, in principle, to achieve complete conversion. In practice, initiator efficiencies vary greatly and it often may be desirable to adjust the initiator to control agent ratio to achieve desirable results.

The surfactant to monomer ratio may be controlled. Suitable ratios of surfactants to monomers are well known in the art. Once emulsions are formed by in-situ surfactant synthesis, the surfactant to monomer ratio may be adjusted further by adding additional surfactant, which may be the same surfactant or a different surfactant that is not necessarily synthesised in-situ.

Polymerisation conditions include the ratio of components, system temperatures, pressure, type of atmosphere, reaction time and other conditions generally known to those ofskill in the art,

In the broadest sense, an emulsion polymerisation is any heterogeneous polymerisation in an aqueous environment. Typically, these systems produce particles of polymer as product. Those skilled in the art recognise many variants of these polymerisations, with typical classifications distinguishing between polymerisations occurring in true emulsions, micro emulsions, mini emulsions, suspensions and dispersions. These processes are generally distinguished by differences in process, components or results, with specific factors including the presence, amount and type of surfactant required; presence, amount and type of initiator; type and amount of monomer, including ^' monomer solubility; polymerisation kinetics; temperature; order of addition of the components, including the timing of addition of the components (e.g., monomer); solubility of the polymeric product; agitation; presence of co-solvents or hydrophobes; resulting particle size; particle stability in the polymerisation system toward coagulation or sedimentation; and other factors known to those skilled in the art.

The "living" nature of the polymerisation processes provide those of skill in the art the ability to create virtually any type of polymer architecture desired, as well as selection from a wide variety of monomers. Thus, this invention includes block copolymers derived from controlled copolymerisation of two or more monomers.

According to Scheme- 1, a multifunctional RAFT 6 arm core (21) can be prepared from hexakis(bromomethyl)benzene (20) by reaction with sodium dithiobenzoate, in an inert solvent such as THF, at about 5O ⁰ C, for about 3 hours. The core (21) can then be reacted with a monomer, such as tert-bv&yl acrylate ( ¹ BA) under standard conditions (AIBN, toluene, 6O ⁰ C), to afford the star branched polymer (22). Polymer (22) can then be reacted with a further monomer under standard conditions (AIBN, toluene, 60 ⁰ C), to afford the copolymer (23). The dithiobenzoate function of polymer (23) can then be cleaved in the presence of a base such as hexyl amine, in an ether such as THF, or other such inert solvent, at about room temperature, for about 12 to 24 hours (overnight), to afford the thiol derivatised polymer (24).

According to Scheme 2, 1,1,1-trihydroxymethyl propane (1) can be reacted with α-bromoρhenyl acetic acid by refluxing 12 - 18 hours (overnight) in toluene to afford derivative (25) which can be subsequently reacted with sodium methyl trithiocarbonate in ethylacetate at room temperature for 4 hours, to afford multifunctional RAFT 3 arm core (26). Core (25) can then be reacted with a monomer such as styrene (under standard conditions: toluene, AIBN ₅ 6O ⁰ C) to afford star polymer (27). Styrene based polymer (27) can be further reacted with another monomer (such as AAEA or 2-(acetoacetoxy)ethyl methacrylate (AAEMA)) under standard conditions (AIBN, toluene, 6O ⁰ C), to afford copolymer (28). The trithiocarbamate can be cleaved with piperidine under standard conditions to afford the thiol derivative (29). According to Scheme 3, derivative (26) as shown in Scheme 2, can be treated with a nitrogenous base, such as piperidine, to afford a thiol derivative (30).

According to Scheme 4, derivative (25) can be used as a multifunctional ATRP 2 arm core. Derivative (25) is reacted with styrene in the presence of CuBr, 2,2'-bipyridyl (BiPy), in toluene at 9O ⁰ C to afford the three-arm styrene star polymer (31). Star polymer (31) is then reacted with the monomer methyl acrylate, in toluene, in the presence of CuBr, BiPy, at 90 ⁰ C, to afford block copolymer (32). The bromo-end groups of star polymer derivative (32), can then be reacted overnight with thiodimethyl formamide at 60 ⁰ C to afford the thiol end group derivative (34). Alternatively, the bromo-end group derivative (32), can be reacted with bis(thiobenzoyl) disulphide in the presence of CuBr and BiPy to afford the dithioester-end group derivative (33). The dithioester derivative (33) can subsequently be treated with a nitrogenous base such as hexylamine, in an inert solvent such as THF, for at about 12 - 18 hours at about room temperature, in order to afford thiol derivative (34),

The word 'comprising' and forms of the word 'comprising' as used in this description does not limit the invention claimed to exclude any variants or additions.

Modifications and improvements to the invention will be readily apparent to those skilled in the art. Such modifications and improvements are intended to be within the scope of this invention. Examples

Various embodiments/aspects of the invention will now be described with reference to the following non-limiting examples. Example 1 Synthesis of metal binding hydrogel micro- and nanoslzed particles

Designer particles suitable for both irreversible metal sequestering were synthesized from 'living' radical polymerization. Dimethyl acrylamide and bisacrylamide monomers were copolymerized via RAFT-mediated emulsion polymerization (Jurardcova et al., 1998) to produce crosslinked hydrogel particles (NPl ). A macromeric RAFT agent was used in the synthesis, namely P (DMA)-RAFT (5CNUR69, M»=4000, PDI=LI l ). The RAFT agent was hydrolysed to thiols (NP2), which are known to bind irreversibly to a wide range of heavy metals (e.g. Hg, Cd, Cu, Pb). In _, cases, where selectivity is required, the dithioester (NPl ) could also be utilized (Bell et al, 2006). These hydrogels (polyacryl amide) exhibit .a high water retaining capacity (greater than 90% of its mass), good mechanical strength and their decomposition products have been shown to pose no environmental threat (Barvenik, 1994). The heavy metal binding properties of these particles could be controlled by manipulation of the emulsion process: (i) particle size can be predetermined by simply changing the method of preparation (Mathur et al., 1996), (ii) water retention and mechanioal properties can be manipulated by the incorporation of other less hydrophilic monomers (e,g, styrene, methylacrylate, methyl methacrylate) or through changing the amount or identity of the crosslinker, and (iii) the metal binding capacity can be firstly controlled by the incorporation of RAFT-agent (Bell et al., 2006) (NPl ), and then hydrolysed to thiol end-groups (NP2), and cage ligands can be attached to NPi to bind to many other metals (Say et al., 2002a, b; Bell et al., 2006). Example 2 Capacity of particles to sequester heavy metals in solution

Experiments were conducted using four different types of particles, (i) control (polymer without xanthate), (ii) xanthate and (iii) thiol (after hydrolysis of xanthate) microsized particles, and (iv) PDMA-RAFT-trithiocarbamate nanosized particles. Particles were added to 10 mL of heavy metal solutions and mixed overnight. A ratio of 1 mole of RAFT to 2 moles of heavy metals was used. Four different metals/metalloid (arsenate, lead, copper and zinc) were selected for the study and only one concentration per metal was tested {i.e. 667 μM As, 9650 μM Pb, 4000 μM Cu and 10000 μM Zh). After centrifugation of the mixing solutions, supernatants containing the fraction of free soluble metals that were not sequestered by the particles (metals bound to the particles were in the pellets) were collected and total metal concentrations analysed via ICP-OES (Inductively Coupled Plasma - Optical Emission Spectroscopy). Capacity of the different types of particles to sequester heavy metals and to ^° reduce their soluble concentrations in the supernatant is presented in Table 1.

Table 1: ^' Capacity of different types of particles to sequester heavy metals in solution. Reduction in soluble metal concentrations in the supernatant is given as the mean ± SE for «=3. Negative values indicate an increase of . metal concentration in the supernatant after particle action.

*Only a limited amount of nanosized particles was available at the time of experimentation and it was possible to test its metal binding capacities with copper only. Results showed that the addition of microsized thiol particles reduced soluble metal concentrations of Cu, Pb and Zn by 75,5, 86.4 and 63.8% respectively (Table 1), Reducing the size of the RAFT functional particles from micro to nanosize resulted in an increase of the percentage of Cu sequestration from 27.1 to 71.8%. This suggests that efficiency _Λ of metal sequestration could be improved by using thiol nanosized, particles. Addition of particles to arsenate solution resulted in an increased arsenic concentration (up to +13%, Table 1 ) in the supernatant.

The result with As was unexpected. An additional mixing experiment was therefore performed using the ratio 10 mole's of xanthate (microsize xanthate particles) to 1 mole of arsenate so as to investigate further. Arsenate concentration in the supernatant was then increased by +66.4% ± 1.2. It was found that this increase of As in the supernatant resulted from the capacity of the particles to exclude As and absorb water instead (same number of moles of free As in a reduced volume of water). This suggests that the particles could be used to exclude As. Synthesis of Preferred Polymeric Particles Example 3:

Preparation of Starting Materials

3.1 Preparation of l-methyl-8-ammine~3, 13 ,16-trithia-6, 10, 19-triazabkyclo [6.6.6βcosane (35). NH ₂ capten (35) was synthesised according to the method described by Gahan ei al,. The macrobicyclic ligand (NH^capten, 35, Figure 7) contains both secondary amine (σ donor) and thioether (π acceptor) metal coordination sites as well as a suitably positioned amine functionality for attachment to the nanoparticle (Figure ■ . 7).

3.2 Preparation of O-ethylxanthyl etfiyl benzene (MADIX) (36).

Synthesis was achieved following a literature procedure (Charmot, D., et at). Potassium 0-ethyldithiocarbonate (3 g, 0,019 mol, Aldrich, 99%) was added to a stirred mixture of (i-bromoethyl) benzene (2.712g, 0.015 mol, Aldrich, 98%) in absolute ethanol (50 mL). The mixture was stirred for 4 h at room temperature under a N ₂ atmosphere. Water (50 mL) was added, and the organic phase was extracted with diethyl ether/pentane (1:2, 3 x 50 mL). These fractions were collected and the solvent was removed under vacuum to obtain 36. Purity was obtained at >99% according to ' H and ' ³ C NMR.

Example 4

Preparation of Functional Nanoparticles (Figure. 2)

4.1 Ab initio emulsion polymerisation of styrene (37).

To a 250 mL three-neck round bottom flask was added water (90 g), STY (40.5 g, 0.389 mol), SDS- (0.4806 g, 0.0017 mol) and 36 (0.3049 g, 0.0013 mol). The solution was stirred and heated at 7O ⁰ C while being degassed with nitrogen sparging for 30 minutes. APS (0.1551 g, 0.679 mmol) was added and the reaction was allowed to proceed under N ₂ for 24 hours. Samples were taken at regular intervals to determine conversion by gravimetry and Molecular Weight Distribution by Size Exclusion Chromatography. The final reaction mixture was dialysed for 3 days with Snakeskin Dialysis Tubing™ to remove low molecular . weight impurities to afford PSTY latex 37. The average particle size was determined by dynamic light scattering. Table 2 gives all experimental conditions to make PSTY nanoparticles, including number-average molecular weights (M _n ), polydispersity index (PDI), particle sizes and number of particles/unit volume (No).

Table 2; List of all experimental conditions in the ab inito and seeded polymerisation of all three emulsions ⁸

a Data of number-average diameter, which was used to calculate number of particles per unit volume (N _c ). All concentrations were calculated from the total reaction volume. b Calculated from Dynamic Light Scattering.

⁰ Aggregation of this sample of nanoparticles prevented accurate analysis for this experiment. . . .

4.2 Seeded emulsion polymerisation of AAEMA onto the PSTY core (38).

The resulting PSTY latex 37 from the above example was used in a second stage emulsion polymerization. The latex 37 was degassed by bubbling N2 with stirring for 30 mm. The reaction temperature was raised to 70° C, and APS (0.1551 g, 0.679 mmol) was added to start polymerization. After 15 min, AAEMA (1.0037 g _? 0.005 mol) was added drop-wise to the vessel via a pressure equalizing side-arm drop funnel over the period of 1 h, and the polymerization stopped after a further 2 h (approximately full conversion). The final latex was quenched by cooling, and then dialysed against MiIIiQ water for 3 days to remove low molecular weight impurities affording latex 38. XPS was used to confirm the presence of AAEMA on the surface of the nanoparticle.

4.3 Coupling of 35 to nanoparticles (39).

The resulting latex 38 from above was used to couple 35 to the particle surface. To ^' a 10 mL stirred solution of the nanoparticles was added dropwise 10 mL of MiUiQ water containing 35 (0.7284 g, 2 mmol) at room temperature. The amount of 35 was in excess of the moles of AAEMA monomer units in latex 38. The reaction mixture was stirred overnight and the resulting coupled nanoparticles were dialysed in Snakeskin Pleated Dialysis Tubing for 2 days to remove any uncoupled ligand 35, thus providing the cage derivatised nanoparticles 39.

Coupling was confirmed by XPS that showed peaks characteristic of sulphur and nitrogen. Example 5 Metal Binding Studies Using Radioisotopes

5.1 Binding studies to capten derivative (35).

Typically radiometal ion solutions were prepared by spiking an accurately know solution of a metal ion (e.g Hg ²⁺ , Pb ²⁺ and Co ²⁺ ) with the respective radiotracers (e.g.Hg-197/Hg-203, Pb-201 and Co-57). The final concentration of Co ²⁺ , Hg ²⁺ and Pb ²⁺ was 0.0261 μM, 0.1466 mM) and 1.8859 μM in a 0.1 M HCl solution. Complexation study typically involved an incubation with accurately known varying concentration of the metal ion (in 20 μL) with accurately known concentration of 35 (0.392 g, 0.001 mol) in 500 μL of sodium acetate buffer (pH = 7) solution. Complexation of metal to 35 was determined by Instant Thin Layer Chromatography (ITLC), by loading 2 μL of the final solution onto an ITLC silica strip and placing it into a running buffer consisting of sodium acetate (pH 4.5, 0.1 M) and ethanol in a 9:1 ratio. Each ITLC strip was dried and cut into ten equal portions. Radioactivity associate with each portion was determined using a Perkin-Elmer Wizard 3" 1480 Automatic Gamma Counter. The free metal ion moved with the solvent front and had a R _f of 1.0. The metal complex remained at the origin with an R _f of 0.0. The percent complexation was determined by the ratio of activity at the origin divided by total radioactivity on ITLC multipled by 100.

5.2 Binding studies to latex 38 and 39.

Metal binding experiments with Co ²⁺ and Hg ²⁺ metal ion solution doped with Co- 57 and Hg-197/Hg-203, respectively, in the presence of 38 and 39 were undertaken (10 minutes, RT; 1 hour 40° C ₅ respectively). The competitive binding experiments were carried out using equal to higher molar ratios of each metal ion. The radioactive emissions characteristic for each radioisotope was used to correlate radioactivity in solution to the concentration of respective metal ion (natural isotope) in solution. This. approach allows accurate detection of metal ions in solution and thus quantitative information on binding efficiencies of each metal to the nanoparticle. The results (Figure 8) under these conditions show the selective binding of 38 (>70%) with Hg-203, 5.5 The effects of temperature, time andpH on binding.

The effect of temperature, time and pH were investigated for each metal ion with the respective ligands system. Optimum conditions for each metal ion is given in

Table 3 below. Table 3:

A typical assay involved incubating 20 μL metal ion solution (e.g Co-57/Co ²⁺ ion) and 20 μL nanoparticles in 500 μL of sodium acetate buffer (0.1 M, pH 7). Each sample was incubated for its optimum time (in the case of Co ²⁺ , at 10 min at room temperature), and then centrifuged on an Eppendorf centrifuge to free the supernatant of nanoparticles (typically 10 min at 13900 rpm). The supernatant was then divided into three equal aliqupts (150 μL each) and associated radioactivity counted using a Perkin-Elmer Wizard 3" 1480 Automatic Gamma Counter for 10s. Where nanoparticles where incubated with mixed radiotracers solution, appropriate gamma emissions for isolated and counted on the gamma counter. Samples were prepared in triplicate, and the amount of metal bound was calculated from these readings by taking the average counts for the supernatant, calculating for the total reaction volume, dividing by the standard counts for the same volume (% free) and subtracting from 100 (% bound). The binding efficiency was also determined over a range of pHs. It should be noted that in the pH range studied there was no coagulation of the polymer nanoparticles.

5.4 Competitive binding assays against Co-57.

To determine the effectiveness and or selectivity of nanoparticle 39 at metal complexation, a series of metal coπψlexation assays were conducted in the presence of four carrier metal ions. The competition metal ions used in this study were Cd ²⁺ , Hg ²⁺ * Pb ²⁺ and Co ²⁴ as nitrate salts. Concentration of each competing metal ion ranged ^" from Ix, 10x, 10Ox and 100Ox higher than the Co ²⁺ concentration (0.0261 μM) in final solution. Co-57 was used to correlate concentration Of Co ²⁺ to radioactivity in solution, Typically 20 μL aliquots of each competing metal ion was added to a 20 μL of Co-57/Co ²⁺ solution, followed by the addition of 20 μt of nanoparticles in 500 μL of bis-tris propane buffer (pH 8). The final reaction mixtures were rotated on rotor for fixed time period then centrifuged and the supernatant samples for radioactivity. Percentage of Co-57 bound to nanoparticles can be correlated to the concentration of Co ²⁺ in solution. The results are displayed in Figure 9.

Example 6

Analytical Methodologies

6.1 ¹ H and ¹³ C Nuclear Magnetic Resonance (NftϊR)

All NMR spectra were recorded on a Broker DRX 500 MHz spectrometer using an external lock (D ₂ O, CDCI ₃ ) and utilizing a standard internal reference (1,4- dioxane, solvent reference), ¹³ C NMR spectra were recorded by decoupling the protons and all chemical shifts are given as positive downfield relative to these internal references.

6.2 Dynamic Light Scattering (DhS)

The average diameters of the nanoparticles were measured using a Malvern Zetasizer 3000HS. The sample refractive index (RI) was set at 1.59 for PSTY. The dispersant RI and viscosity were set to 1.33 and 0.89 Ns/m ² respectively. The number average particle diameter was measured for each sample to determine each diameter and from this the number of particles per unit volume in solution (Nc) were calculated.

6.3 Size Exclusion Chromatography (SEC)

The molecular weight distributions of nanoparticles were measured by SEC. All polymer samples were dried prior to analysis in a vacuum oven for two days at 40° C. The dried polymer was dissolved in tetrahydrofuran (THF) (Labscan, 99%) to a concentration of 1 mg/mL. This solution was then filtered through a 0.45 μm PTFE syringe filter. Analysis of the molecular weight distributions of the polymer nanoparticles was accomplished by using a Waters 2690 Separations Module, fitted with two Ultrastyragel linear columns (7.8 x 300 mm) kept in series. These columns were held at a constant temperature of 35° C for all analyses. The columns used separate polymers in the molecular weight range of 500 ~ 2 million g/mol with high resolution. THF was the eluent used at a flow rate of 1.0 mL/min. Calibration was carried out using narrow molecular weight PSTY standards (PDI < 1.1) ranging from 500 - 2 million g/mol. Data acquisition was performed using Waters Millennium software (ver. 3.05,01) and molecular weights were calculated by using a 5 ^til order polynomial calibration curve,

6.4 X-ray Photoelectron Spectroscopy (XPS)

XPS was used to determine whether 1 was covalently attached to the surface of the nanoparticles. The latex consisting of the nanoparticles was cast onto a glass plate, and dried under vacuum for 2 days at room temperature. Data was acquired using a Kratos Axis ULTRA X-ray Photoelectron Spectrometer incorporating a 165 mm hemispherical electron energy analyser. The incident radiation was Monochromatic Al X-rays (1486.6 eV) at 150W (15 kV, 10 mA). Survey (wide) scans were taken at analyser pass energy of 160 eV and multiplex (narrow) high resolution scans at 20 eV. These scans were carried out over 1200 - 0 eV binding energy range with 1.0 eV steps and a dwell time of 100 ms. Narrow high- resolution scans were run with 0.1 eV steps and 250 ms dwell time. All samples were dried in a vacuum oven prior to insertion into the instrument and, once inside, remained in a vacuum overnight to ensure that no water or solvent molecules remained. SEM showed that the film consisted of a coagulation of polymer particles, in which there was little or no polymer mixing between particles. This shows that the XPS measures the surface atoms and not the bulk of the nanoparticles. See Figure 10.

6.5 Scanning Electron Microscopy (SEM)

^• The films from above were also characterised by SEM on a Jeol 6300 and the Jeol 890 SEM instruments. All samples (unless stated otherwise), were sputter coated with Pt(s) at a thickness of 15 nm. The 6300 was used to look at polymer nanoparticles using an electron beam at 5 kV and 8 mm aperture, while the 890 was used for observing the thin film packing of the polymer nanoparticles using an electron beam a 2 kV. See Figure 11.

Examples 7 & 8

Examples 7 & 8 were conducted using the set ups depicted in Figure 1 and Figure

2. Preparation of the ore

Laterite ore was initially crushed to pass a 63 μm diameter sieve. Example 7 and Example 8(a) were carried out using agglomerated laterite. Example 8(b) was carried out using non-agglomerated material .

Agglomerates were formed in a rolling drum and were gradually wetting as they rolled in the drum using 5M sulphuric acid, A range of agglomerate sizes were thus produced. Agglomerates size distributions were measured. For Example 7 and Example 8, ore was placed in acid-resistant plastic cores of 100 mm diameter and height 150 mm. Each core was packed using a random selection of agglomerates but with the same size distribution with a weighting towards the large agglomerates as this better matches the sizes used in industry in conventional positive fluid potential leaching processes of the prior art. Example 7 Conventional treatment

The conventional treatment was configured according to Figure 1, optimised to simulate ideal conditions by minimising constraints associated with preferential flow, reprecipitation, acid recirculation and overburden pressure.. The treatment was not optimised in terms of acid dissolution. The conventional approach was simulated experimentally by applying 2M sulphuric acid through hypodermic needles at an approximately constant rate. All out flowing solution was collected and analysed fox a range of metals including nickel. The concentration of out flowing solution could have been higher if the columns had been longer. Equally the acid consumption would have increased from the top to bottom of the core reducing the dissolution potential at the bottom. Therefore, a linear increase in concentration with core length would not necessarily be expected. Example 8 Extraction using zero/negative fluid potential

One embodiment of the extraction according to the present invention was configured according to Figure 2. When the dust treatment was first wet up, micro- aggregates (~1 to 2 mm diameter) spontaneously formed. This phenomenon has been previously described experimentally in the study of agricultural soil stability to wetting. Figures 3 and 4 depict the results for the nickel recovery on a mass basis. Figure 3 shows the results plotted against the cumulative acid input to the conventional treatment (Example 1). Approximately 17.5 litres of 2M sulphuric acid leachant were added over a period of several months, Sampling times were regular at the outset but became more controlled by time and accumulation of acid later in the experiment. The results are plotted in terms of nickel outflow per unit mass of ore in each core to account for the different mass of ore in each core. Ultimately all treatments should finish at the same value which is the nickel content of the ore. Agglomerate and non-agglomerated laterite

The present invention works effectively with both agglomerated and non- agglomerated laterite. This is because the need for large pore space for gravity flow of acid has been eliminated. With clever sizing of heap particles it is possible to enhance the process of the present invention by creating pores between the particles that will draw in acid. ^■

The agglomerated and non-agglomerated heaps of Examples 8(a) and 8(b) had similar total acid uptake. However the non-agglomerated heap had more pore space, that is, the pores in the particles were larger than those inside agglomerates but not as large as , those between the agglomerates. The pores were formed as a result of spontaneous micro-agglomerate formation upon initial wetting - an effect that has been previously described in soil science, Elimination of an agglomeration step in mineral processing represents a considerable economic advantage in terms of capital and operating costs.

Figure 3 shows that far more acid is required to extract nickel using the conventional treatment (Example 7) as compared with the process of the present invention (Examples 8(a) and 8(b)).

Figure 4 shows the difference between the conventional treatment and the process of the present invention for the first 1 litre of acid added. In general, Example 8(a) again out performed the conventional process of Example 7.

The process of Example 8(b) (no aggregates) out performed both the agglomerate treatment of Example 8(a) and the conventional treatment of Example 7.

Extrapolation of the rate of nickel production provided by Example 8(b) indicates that extraction of non-agglomerated and agglomerated laterite according to the present invention would consume 2.2% and 5% respectively, of the acid required for the conventional treatment

Figures 5 and 6 show the outflow pregnant solution concentrations from Examples 7, 8(a) and 8(b). The treatments of the present invention (Examples 8(a) and 8(b)) outperform the conventional treatment (Example 7) to a significant degree in concentration terms. The conventional treatment of Example 7 shows an initial peak of relatively high concentration followed by a long tail of low concentration. This is consistent with expected behaviour of conventional heaps. Drawings

Various embodiments/aspects of the invention will now be described with reference to the following drawings in which,

• Figure l is a schematic drawing of the conventional approach to mineral leaching;

• Figure 2 is a schematic drawing of the approach to mineral leaching according to the present invention;

• Figure 3 is a plot comparing the results of Example 7 (using the approach depicted in Figure 1) with the results of Example 8 (using the approach depicted in Figure 2);

• Figure 4 is a plot showing the first 1000 ml of the results shown in Figure 3 ;

• Figure 5 is a plot comparing the outflow pregnant leachant concentrations from Example 7 with the results of Example 8; and

• Figure 6 is a plot comparing the outflow pregnant leachant concentrations from Example 7 with the results of Example 8.

• Figure 7 is a depiction of a synthetic procedure for the preparation of core-shell nanopolymer particles suitable for use in the process of the present invention.

• ^" Figure 8 is a plot depicting the uptake of Co-57 and Hg-197/Hg-203 in -the presence of 38 and 39.

• Figure 9 is a plot depicting the results of competitive binding experiments for Co- 57 with increasing concentrations

• Figure 10 is an X-ray photoelectron spectroscopy (XPS) analysis of polymeric nanoparticles; 38 (top) and 39 (bottom).

• Figure 11 is a scanning electron microscopy (SEM) image of nanoparticles 39 dried on a glass plate.

Figure 1

Figure 1 depicts schematically the conventional prior art approach to heap leaching of nickel laterite agglomerate using positive fluid pressure. Leachant (1) comprising sulphuric acid is irrigated onto the top of the laterite heap (2) and low concentration pregnant solution (3) drains under gravity and is collected at the base of the laterite heap. In this approach, contact time is largely controlled by the residence time of the leachant as it moves through the laterite heap. This is in turn controlled by gravity and the permeability properties of the laterite. There is little evidence in practice that the pore size distribution (and therefore permeability properties) is easily controlled during the process of agglomerate formati on.

In this conventional system of the prior art, the quantity of acid passed through the heap over time is principally a function of the ore permeability, heap height and rate of acid application. This results in consumption of large volumes of acid, low concentration of metals in the out flowing pregnant solution, but a significant concentration of unreacted acid. The leachant flow concentrations are inconsistent over time in different parts of the laterite heap. The conventional process also contributes to heap instability and potentially, the eventual geotechm'cai failure of the heap. A great deal of leachant also passes between the laterite agglomerates, the amount depending on permeability properties and rate of acid application. Leachant passing between the agglomerates has little effect in terms of mineral dissolution because the external surface of agglomerates is relatively small compared to the internal surface area, Figure 2

Figure 2 is a schematic drawing of a mineral leaching process employing zero- or negative fluid potential. Figure 2 represents only one embodiment by which the porous plate (or membrane) can be arranged with respect to the ore and the person skilled in the art will appreciate that many other arrangements could be used to carry out the process of the present invention.

Figure 2(a) depicts addition of the leachant (11) comprising sulphuric acid to the laterite heap (12). This is achieved by applying a zero fluid potential at the interface (13) between the ore and a controlling porous plate (or membrane). Once the ore has absorbed as much acid as it can, no more acid enters the heap. A significant advantage of this wetting approach is that the ore is evenly wet and preferential leachant flow pathways do not form. The leachant remains in contact with the ore as long as required to consume all the acid and therefore maximise dissolution of the mineral ' from the ore before the extraction phase is commenced.

Figure 2(b) depicts collection of pregnant leachant (21) before extraction is complete, that is, the pores in lower agglomerates (22) still contain pregnant leachant. Extraction of the pregnant leachant is achieved by applying suction (negative head or tension) to the interface (13) between the heap and at the porous plate (or membrane). The pregnant leachant is drawn from the pores inside the ore by the porous plate which is held under tension by dropping the free liquid surface to some distance below the interface (and this is called the suction or negative head). The magnitude of the suction controls the minimum diameter of pores from which the pregnant solution can be extracted. Larger suction drains or extracts pregnant leachant from smaller pores. Suction is simply achieved by lowering the liquid in the receiving reservoir. Greater suction can be achieved using various means such as a vacuum pump.

The volume of acid consumed from the leachant according to the process depicted in Figure 1 is dramatically reduced as compared to the. conventional process depicted in Figure 1. Firstly, in the process of Figure 1 the leachant added is only that which the heap takes up under suction, This volume is much small than the total pore volume in the heap (per unit volume of the heap) because the large pores between agglomerates are not filled with leachant. Secondly, the leachant is left in place to incubate until most, if not all of the acid has been reacted. Ideally, the pregnant solution will have little or no acid content, because all of it-has reacted with mineral. Figures 3 and 4

Figure 3 and Figure 4 are plots comparing the results of Example 7 (using the approach depicted in Figure 1) with the results of Example 8 {using the approach depicted in Figure 2 for agglomerated and non-agglomerated laterite) in terms of Ni outflow per unit mass of laterite. The same data is depicted in both figures but the scale has been changed to more clearly show the differences. Figures S and 6

Figures 5 and 6 are plots comparing the outflow pregnant leachant concentrations (in terms of nickel output per unit of acid applied) from Example 7 (using the approach depicted in Figure 1) with the results of Example 8 (using the approach depicted in Figure 2 for agglomerated and non-agglomerated laterite). Figure 7

Figure 7 depicts a synthetic procedure for the preparation of core-shell nanopolymer particles suitable for use as metal-binding particles in the process of the present invention with surface functionality made by the RAFT process, (i) Ab initio emulsion polymerisation of styrene in the presence of xanthate, 36, (iϊ) block copolymerization of AAEMA to form a core-shell nanoparticle (38), and (iii) coupling of the macrobicyclic ligand, 35, onto the nanoparticles (39). The transmission electron microscopy (cryo-TEM) image provides strong evidence that this method does produce core-shell morphologies. Figure 8

Figure 8 is a plot depicting the uptake of Co-57 and Hg-197/Hg-203 in the presence of 38 and 39 (10 minutes, RT; 1 hour, 40 ⁰ C, respectively; [Co] = 0,967 nM, [Hg] = 5.423 μM). Figure 9

Figure 9 is a plot depicting the results of competitive binding experiments for Co- 57 with increasing concentrations (1, 10, 100, 1000 fold excess) of non-radioisotope carrier metals (Cd(II), Pb(II) and Hg(II)) (10 min, RT; Ix, [Co, Cd, Pb, Hg] = 0.9321 nM; 10x, [Co] = 0.9321 nM, [Cd ₅ Pb, Hg] = 9.321 nM; 10Ox, [Co] = 0.9321 nM, [Cd, Pb, Hg] = 93.21 nM; 100Ox, [Co] = 0.9321 nM, [Cd, Pb, Hg] = 932.1 nM). Figure 10

Figure 10 is a X-ray photoelectron spectroscopy (XPS) analysis of polymeric nanoparticles; 38 (top) and 39 (bottom). Figure 11

Figure 11 is an SEM image of nanoparticles 39 dried on a glass plate.

The word 'comprising' and forms of the word 'comprising' as used in this description and in the claims does not limit the invention claimed to exclude any variants or additions.

Modifications and improvements to the invention will be readily apparent to those skilled in the art. Such modifications and improvements are intended to be within the scope of this invention.

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