process

Abstract

Disclosed herein is a method of extracting metal from a metal sulfide containing material comprising the steps of: a) providing an aqueous acidic oxidant mixture comprising water, an acid, an oxidising means, and a halide ion source, wherein the aqueous acidic oxidant mixture has a pH of less than 7; wherein the oxidising means comprises hydrogen peroxide, ozone, oxygen, chlorine, bromine, iodine, hypochlorous acid, hypobromous acid, hypoiodous acid, a hypochlorite salt, a hypobromite salt, a hypoiodite salt, a percarbonate salt, a persulfate salt, a permanganate salt, an anode connected to a power source, or combinations thereof; b) contacting the aqueous acidic oxidant mixture with the metal sulfide containing material to extract the metal from the metal sulfide containing material and form a metal halide solution; wherein the metal comprises copper, nickel, lead, zinc, or combinations thereof.

Description

FIELD OF THE INVENTION The present disclosure concerns methods of extracting metal from a metal sulfide containing material, wherein the metal comprises copper, nickel, lead, zinc. BACKGROUND Copper, nickel, lead and zinc have a variety of different uses and applications. In recent years, there has been a significant increase in the demand for such metals and their salts, creating a desire to efficiently extract these metals from the associated metal-containing materials. Extraction processes for other metals are known in the art. For example, methods of extracting precious metals (such as gold or silver) are known. Generally, such methods involve extracting precious metal from the precious metal containing material (usually referred to as the “leaching” of precious metal from the precious metal containing material) and then capturing the leached precious metal from the solution. For example, some methods use highly poisonous inorganic cyanides to extract the precious metal from the precious metal containing material. Such processes are associated with considerable environmental concerns (where accidental leakages can result in environmental contamination) as well as considerable health and safety concerns (where inadvertent cyanide exposure can cause notable human health concerns). Other methods for extracting precious metals are disclosed in WO 2017 / 158561. However, these methods have been used only for extracting what are generally referred to as precious metals (such as gold and / or silver, amongst others such as platinum and palladium). Also in the prior art is WO2023 / 057754, which concerns methods for extracting lithium, and WO2023 / 026041, which primarily assess extraction of gold and / or silver. Methods often involve flotation of the different metals followed by treatment in a smelter. Meanwhile, copper, nickel, lead and zinc are metals of a different nature, evident from their contrasting location in the periodic table. Furthermore, copper, nickel, lead and zinc are often found in the associated metal-containing materials as sulfide salts, which has historically led to challenges in achieving efficient extraction due to the propensity for the sulfide to interfere with the leaching process, for example due to poor selectivity for the metal, and the reaction with sulfur prior to metal extraction. It is also thought that further challenges exist due to the formation of a passivation layer, where the passivation layer blocks the leaching mixtures from reaching the metals to be extracted. As a result, challenges exist for extracting copper, nickel, lead and / or zinc, particularly from materials that comprise these metals as one or more sulfide salts. Existing methods for extraction from sulfide-containing materials lack favourable kinetics or have poor environmental credentials. Accordingly, there remains a need for new methods of extracting copper, nickel, lead and / or zinc, particularly from materials that comprise these metals as one or more sulfide salts. SUMMARY OF INVENTION Disclosed herein, there is a method of extracting metal from a metal sulfide containing material comprising the steps of: a) providing an aqueous acidic oxidant mixture comprising water, an acid, an oxidising means, and a halide ion source, wherein the aqueous acidic oxidant mixture has a pH of less than 7; wherein the oxidising means comprises hydrogen peroxide, ozone, oxygen, chlorine, bromine, iodine, hypochlorous acid, hypobromous acid, hypoiodous acid, a hypochlorite salt, a hypobromite salt, a hypoiodite salt, a percarbonate salt, a persulfate salt, a permanganate salt, an anode connected to a power source, or combinations thereof; b) contacting the aqueous acidic oxidant mixture with the metal sulfide containing material to extract the metal from the metal sulfide containing material and form a metal halide solution; wherein the metal comprises copper, nickel, lead, zinc, or combinations thereof. It has surprisingly been found that the aqueous acidic oxidant mixture achieves particularly successful extraction of copper, nickel, lead and / or zinc, from materials that comprise one or more sulfide salts of copper, nickel, lead and / or zinc. It is thought that the combination of water, an acid, an oxidising means, and a halide ion source, overcomes the challenges associated with extraction in the presence of sulfide salts, addresses the challenges associated with any potential passivation layer formation, and provides improved kinetics for metal extraction. Moreover, it was surprisingly found that the improved extraction can be achieved using more environmentally friendly components, rather than resorting to less environmentally friendly components, such as cyanide, pyrotechnic technologies, or ferric oxidants, for example. Furthermore, extracting the copper, nickel, lead and / or zinc as a halide provides significant advantages due to the increased solubility in water of the halide salt, allowing less water to be used, and so further reducing the environmental impact and carbon footprint. DETAILED DESCRIPTION Used throughout, the language “up to” means “up to an including”. Used throughout, it will be understood that the phrase “in the range of’ is inclusive of the end points of that range. The present disclosure concerns a method of extracting metal from a metal sulfide containing material, wherein the metal comprises copper, nickel, lead, zinc, or combinations thereof. It will be understood from this that the method disclosed herein is a method of extracting copper, nickel, lead, zinc, or combinations thereof, and the metal sulfide containing material includes one or more sulfide salts of copper, nickel, lead, zinc, or combinations thereof. In some scenarios, the metal comprises copper, nickel and / or zinc, and the metal sulfide containing material is a copper sulfide, nickel sulfide and / or zinc sulfide containing material (i.e. a material including one or more sulfide salts of copper, nickel and / or zinc). Preferably, the metal comprises copper and / or zinc, and the metal sulfide containing material is a copper sulfide and / or zinc sulfide containing material (i.e. a material including one or more sulfide salts of copper and / or zinc). More preferably, the metal comprises copper, and the metal sulfide containing material is a copper sulfide containing material (i.e. a material including one or more sulfide salts of copper). The method disclosed herein is concerned with extracting from a metal sulfide containing material, i.e. a material that contains one or more sulfide salts of copper, nickel, lead, zinc, or combinations thereof. It will be appreciated that there are various possible sulfide salts that may be present in the metal sulfide containing material, even for a given metal. It will also be appreciated that other components may be present in a given metal sulfide salt, where the metal sulfide salt need not be exclusively composed of sulfide plus copper, nickel, lead and / or zinc. For example, the metal sulfide containing material may include sulfide salts such as CuFeS2, Cu2S, Cu5FeS4, (FeNi)9Sa, PbS, (Zn,Fe)S, or combinations thereof. Preferably, the metal sulfide containing material includes CuFeS2, Cu2S, Cu5FeS4, (Zn,Fe)S, or combinations thereof. More preferably, the metal sulfide containing material includes CuFeS2, Cu2S, Cu5FeS4, or combinations thereof. Various examples of metal sulfide containing material are disclosed herein. In some instances, the metal sulfide containing material may fall into a generic class of materials - in such instances, it will be appreciated that the stated metals (i.e. copper, nickel, lead, zinc, or combinations thereof) may not be contained in all materials in the generic class. For example, the metal sulfide containing material can, for example, be an ore (a naturally occurring rock or sediment) - however not all ores contain one or more sulfide salts of copper, nickel, lead, zinc, or combinations thereof. The skilled person will appreciate and be able to determine whether and when a particular material constitutes a metal sulfide containing material, namely a material including one or more sulfide salts of copper, nickel, lead, zinc, or combinations thereof. The metal sulfide containing material can take various forms, as will be appreciated by the skilled person. It will be appreciated that the metal sulfide containing material may comprise additional non-sulfide metal salts. The metal sulfide containing material can, for example, be selected from an ore (a naturally occurring rock or sediment), including a concentrate of such ore, sea water, subsurface brines, waste material, a metal mixture, a human body component, a medical device, or a consumer product. Examples of an ore include mineral deposits (such as mineral veins) and the like obtained from waterways, causeways, mines, and other Earth-bound sources known in the art. Preferred examples of an ore include an ore of Chalcopyrite (CuFeS2), Chalcocite (Cu2S), Bornite (CusFeS^, Pentlandite ((FeNi)9Ss), Galena (PbS), Sphalerite ((Zn,Fe)S), or a combination thereof. Examples of a human body component include teeth, bones, heart, muscle, joints, legs, arms, hands, fingers, knees, feet, among others. Examples of medical devices include life support systems and devices, such as a diagnostic machine, a dialysis machine, a medical implant (for example, a pacemaker), a tooth filling, tooth enamel, tooth inlay, dentures, an artificial joint, an artificial limb or other artificial appendage, or materials removed after diagnostic, radiodiagnostic or therapeutic administration that comprise e.g. metalcontaining nanoparticles. Examples of consumer products include a jewellery item, an electronics item, and other metal products such as an ingot, bar or currency coin. Examples of a jewellery item include a ring, a bracelet and a necklace, among others. Examples of an electronics item include a computer, a monitor, a power supply, an amplifier, a preamplifier, a digital to analog converter, an analog to digital converter, a battery (for example a lead acid battery), and a phone, among others. Examples of waste material includes tailings from previous mining efforts, bio-waste, and waste derived from sewer plants. The skilled person will appreciate that the metal sulfide containing material may contain various levels of copper, nickel, lead and / or zinc, depending on the type of metal sulfide containing material. The methods disclosed herein are effective at a variety of levels. For example, the metal sulfide containing material may comprise copper, nickel, lead and / or zinc in an amount ranging from 0.001 to 15% by weight. The metal sulfide containing material may comprise copper, nickel, lead and / or zinc in levels of at least 0.001% by weight, at least 0.01% by weight, or at least 0.05% by weight. The metal sulfide containing material may comprise copper, nickel, lead and / or zinc in levels of up to 15% by weight, up to 12% by weight, or up to 10% by weight. The metal sulfide containing material may comprise copper in levels in the range of of 0.05-7% by weight. The metal sulfide containing material may comprise nickel in levels in the range of 35% by weight. Preferably, the metal sulfide containing material is an ore (i.e. an ore that contains one or more sulfide salts of copper, nickel, lead and / or zinc) a subsurface brine, a battery, or a combination thereof. More preferably, the metal sulfide containing material is an ore of Chalcopyrite (CuFeS2), Chalcocite (Cu2S), Bornite (Cu5FeS4), Pentlandite ((FeNi)9Sa), Galena (PbS), Sphalerite ((Zn,Fe)S), a subsurface brine, a battery, or a combination thereof. Most preferably, the metal sulfide containing material is an ore of Chalcopyrite (CuFeS2), Chalcocite (Cu2S), Bornite (CusFeS^, or a combination thereof. Preferably, the metal sulfide containing material is a battery, in particular a spent or partially spent battery. In such scenarios, the method disclosed herein provides an effective means of recycling spent or partially spent batteries. As such, the method disclosed herein provides a surprising new means to recycle batteries. By applying the method disclosed herein to a battery, in particular a spent or partially spent battery, metal halide can be extracted and used for a variety of different industrial purposes. It will be appreciated that “spent or partially spent” is used to refer to batteries that have been fully or partially used for a particular purpose. Preferably, the metal sulfide containing material is an ore (i.e. an ore that includes one or more sulfide salts of copper, nickel, lead, zinc, or combinations thereof). More preferably, the the metal sulfide containing material is an ore containing copper, nickel, lead and / or zinc at a level of 0.001 to 15% by weight, preferably 0.05 to 10% by weight. As will be appreciated by the skilled person, an ore may be subjected to preliminary steps such as reducing the size of its particles and / or agglomerating particles to provide controlled size agglomerates. The ore may be reduced in size so as to be processable as fluid slurry, and brought into contact with the oxidant mixture in vats. Preferably, the ore is crushed with crush sizes in the range of 11000 micron, more preferably in the range of 5-200 microns. The ore may also be subjected to pre-treatment in a pressure oxidative system which can involve heating to a temperature from 200°C to 2000°C, but more typically to a temperature from 600°C to 1300°C. Separately or in combination with the above, the ore can also be concentrated by gravity concentration or by flotation. Disclosed herein, there is the step of providing an aqueous acidic oxidant mixture comprising water, an acid, an oxidising means, and a halide ion source (also referred to as “a source of halide ion”), wherein the aqueous acidic oxidant mixture has a pH of less than 7. This is denoted herein as step a). In step a), without wishing to be bound by theory, it is thought that the oxidising means interacts with the halide ion to form halide species such as [Hal]OH (where [Hal] is a halide), but it is also theorised that other such species may form, such as Hal2, Hal3‘. Disclosed herein, the “aqueous acidic oxidant mixture” refers to the mixture formed when combining the water, acid, oxidising means, and a halide ion source. The water present may be tap water, well water distilled water, recycled water, or sea water. Disclosed herein, the oxidising means comprises hydrogen peroxide, ozone, oxygen, chlorine, bromine, iodine, hypochlorous acid, hypobromous acid, hypoiodous acid, a hypochlorite salt, a hypobromite salt, a hypoiodite salt, a percarbonate salt, a persulfate salt, a permanganate salt, an anode connected to a power source, or combinations thereof. It will be understood that the term “oxidising means” takes its usual definition in the art, and so refers to a component capable of acting as an oxidant, and can for example be a chemical reagent (usually referred to as an oxidising agent), or a component of a system suitable for achieving oxidation by electrolysis, for example an anode connected to a power source. Preferably, the oxidising means comprises hydrogen peroxide, ozone, oxygen, chlorine, bromine, iodine, hypochlorous acid, hypobromous acid, hypoiodous acid, a hypochlorite salt, a hypobromite salt, a hypoiodite salt, a percarbonate salt, a persulfate salt, a permanganate salt, or combinations thereof. More preferably, the oxidising means comprises hydrogen peroxide, ozone, chlorine, bromine, iodine, hypochlorous acid, hypobromous acid, hypoiodous acid, a hypochlorite salt, a hypobromite salt, a hypoiodite salt, a percarbonate salt, a persulfate salt, a permanganate salt, or combinations thereof. Even more preferably, the oxidising means comprises hydrogen peroxide, ozone, a percarbonate salt, a persulfate salt, a permanganate salt, or combinations thereof. Most preferably, the oxidising means comprises hydrogen peroxide. When the oxidising means is a chemical reagent (such as hydrogen peroxide, ozone, oxygen, chlorine, bromine, iodine, hypochlorous acid, hypobromous acid, hypoiodous acid, a hypochlorite salt, a hypobromite salt, a hypoiodite salt, a percarbonate salt, a persulfate salt, a permanganate salt, or combinations thereof) the chemical reagent can be used in various amounts to form the aqueous acidic oxidant mixture. Preferably, when the oxidising means is a chemical reagent (such as such as hydrogen peroxide, ozone, oxygen, chlorine, bromine, iodine, hypochlorous acid, hypobromous acid, hypoiodous acid, a hypochlorite salt, a hypobromite salt, a hypoiodite salt, a percarbonate salt, a persulfate salt, a permanganate salt, or combinations thereof), the amount of oxidising means added to form the aqueous acidic oxidant mixture relative to the amount of the halide ion source added to form the aqueous acidic oxidant mixture is in the range of 0.1:1 to 10:1 by weight, more preferably in the range of 1:1 to 10:1 by weight. The skilled person will appreciate that the oxidising means may be generated in situ where appropriate. The skilled person will appreciate that “ozone” refers to O3. Ozone can be introduced as a gas by bubbling through the remaining components to form the aqueous acidic oxidant mixture. Ozone can be generated in situ by a variety of possible methods, as will be appreciated by the skilled person The skilled person will appreciate that “chlorine” refers to CI2. Chlorine can be introduced as a gas by bubbling through the remaining components to form the aqueous acidic oxidant mixture. Chlorine can be generated in situ by a variety of possible methods, as will be appreciated by the skilled person. In situ generation is preferred due to reduced toxicity. The skilled person will appreciate that “oxygen” refers to O2. Oxygen can be introduced as a gas by bubbling through the remaining components to form the aqueous acidic oxidant mixture, including dissolved oxygen. Oxygen can be generated in situ by a variety of possible methods, as will be appreciated by the skilled person. The skilled person will appreciate that “bromine” refers to Br2. Bromine can be introduced as a liquid or a gas. For example, bromide may be provided for use in the method as part of an aqueous solution which can vary in concentration, possible concentrations being 5-100 wt.%, 5-70 wt.%, 20-70 wt.%, 30-70 wt.%, or 30-60 wt.%. Bromide can be introduced as a gas by bubbling through the remaining components to form the aqueous acidic oxidant mixture, and / or the bromide can be generated in situ by a variety of possible methods, as will be appreciated by the skilled person. The skilled person will appreciate that “iodine” refers to l2. Iodine may be added directly as a solid to form the aqueous acidic oxidant mixture, or, it may be provided for use in the method as part of an aqueous solution which can vary in concentration, possible concentrations being 5-100 wt.%, 5-70 wt.%, 20-70 wt.%, 30-70 wt.%, or 30-60 wt.%. The skilled person will appreciate that “hypochlorous acid” refers to HOCI. This may be provided for use in the method as part of an aqueous solution which can vary in concentration, possible concentrations being 5-100 wt.%, 5-70 wt.%, 20-70 wt.%, 30-70 wt.%, or 30-60 wt.%. The skilled person will appreciate that “hypobromous acid” refers to HOBr. This may be provided for use in the method as part of an aqueous solution which can vary in concentration, possible concentrations being 5-100 wt.%, 5-70 wt.%, 20-70 wt.%, 30-70 wt.%, or 30-60 wt.%. The skilled person will appreciate that “hypoiodous acid” refers to HIO. This may be provided for use in the method as part of an aqueous solution which can vary in concentration, possible concentrations being 5-100 wt.%, 5-70 wt.%, 20-70 wt.%, 30-70 wt.%, or 30-60 wt.%. The skilled person will appreciate that “hypochlorite salt” refers to any salt capable of generating the hypochlorite anion (CIO-) in solution. Preferably, the hypochlorite salt is an alkali metal hypochlorite salt e.g. lithium hypochlorite, potassium hypochlorite, calcium hypochlorite, and / or sodium hypochlorite. Preferably, the hypochlorite salt is sodium hypochlorite. The skilled person will appreciate that “hypobromite salt” refers to any salt capable of generating the hypobromite anion (BrO-) in solution. Preferably, the hypobromite salt is an alkali metal hypobromite salt e.g. lithium hypobromite, potassium hypobromite, and / or sodium hypobromite. Preferably, the hypobromite salt is sodium hypobromite. The skilled person will appreciate that hypoiodite salt refers to any salt capable of generating the hypoiodite anion (IO-) in solution. Preferably, the hypoiodite salt is an alkali metal hypoiodite salt e.g. lithium hypoiodite, potassium hypoiodite, and / or sodium hypoiodite. Preferably, the hypoiodite salt is sodium hypoiodite. The skilled person will appreciate that percarbonate salt refers to any salt of the formula X2H3CO6, wherein X is a cation such as lithium, potassium, or sodium. Preferably, the percarbonate salt is an alkali metal percarbonate salt e.g. lithium percarbonate, potassium percarbonate, and / or sodium percarbonate. Preferably, the percarbonate salt is sodium percarbonate. The skilled person will appreciate that persulfate salt refers to any salt capable of generating persulfate anions SO52’ and / or S2O82’ in solution and this includes caro’s acid. Preferably, the persulfate salt is lithium persulfate, potassium persulfate, calcium persulfate and / or sodium persulfate. Preferably, the persulfate salt is sodium persulfate. The skilled person will appreciate that “permanganate salt” refers to any salt capable of generating the permanganate anion (MnCV) in solution. Preferably, the permanganate salt is an alkali metal permanganate salt e.g. lithium permanganate, potassium permanganate, and / or sodium permanganate. Preferably, the permanganate salt is potassium permanganate. The skilled person will appreciate that an anode is an electrode at which oxidation occurs. Generally, the anode is at least partially (or, fully) submerged in the aqueous acidic oxidant mixture. The anode is connected to a power source which is capable of applying an electrical current such that the electrons flow away from the anode, thereby allowing oxidation (i.e. loss of electrons) to occur at the anode. This is generally referred to as oxidation by electrolysis, and so the skilled person will appreciate that the power source will in turn usually be connected to a cathode. The skilled person will appreciate that “hydrogen peroxide” refers to H2O2. The use of hydrogen peroxide provides an economic, commercial and environmental preference to other oxidants. The use of hydrogen peroxide is particularly preferred. More specifically, hydrogen peroxide is available commercially at very large scale and the breakdown products are water and oxygen, resulting in environmentally friendly credentials. Various amounts of hydrogen peroxide may be used to form the aqueous acidic oxidant mixture. Preferably, the amount of hydrogen peroxide added to form the aqueous acidic oxidant mixture relative to the amount of the halide ion source added to form the aqueous acidic oxidant mixture is in the range of 0.1:1 to 10:1 by weight, more preferably in the range of 1:1 to 10:1 by weight. Hydrogen peroxide may be provided for use in the method as part of an aqueous solution which can vary in concentration, possible concentrations being 5-100 wt.%, 5-70 wt.%, 20-70 wt.%, 30-70 wt.%, or 30-60 wt.%. Hydrogen peroxide is available from many companies on a commercial basis and can be supplied at large scale by road or rail. These companies include but are not limited to Evonik, Solvay GmbH, Kemira, Arkema. Some companies offer the concept of on site generation, which may be compatible with the method disclosed herein. The inventors of the present application have found that the halide ion source can take a variety of different possible forms and still result in successful extraction of copper, nickel, lead and / or zinc. The halide ion source may be supplied as a liquid (such as an aqueous solution or dispersion), a solid, or a gas. The halide ion source can for example be generated from a halide gas (e.g. when generating a source of chloride ion), a halide gas / liquid (e.g. when generating a source of bromide ion) or a halide solid / liquid (e.g. when generating a source of iodide ion). The inventors of the present application have found that the halide ion source can include a variety of different possible halides and still result in successful extraction of copper, nickel, lead and / or zinc. Preferably however, the halide ion source comprises a bromide ion source, a chloride ion source, an iodide ion source, or combinations thereof. More preferably, the halide ion source comprises a bromide ion source, a chloride ion source, or combinations thereof, as such scenarios result in particularly good extraction. In some scenarios, the halide ion source may be at least one bromide ion source. The halide ion source can be a halide salt. Preferably, the halide ion source is at least one metal halide. When the halide ion source is at least one 13 metal halide, the metal can be lithium, potassium, sodium, calcium, magnesium or combinations thereof. More preferably, the halide ion source is at least one alkali metal halide. When the halide ion source is at least one alkali metal halide, said alkali metal can be lithium, potassium, sodium, or combinations thereof. In a preferred scenario, the halide ion source is sodium halide and / or potassium halide, particularly when the halide is chloride. Various amounts of the halide ion source may be used to form the aqueous acidic oxidant mixture. The amount of the halide ion source added to form the aqueous acidic oxidant mixture can for example range from 1 to 20 wt.% based on the total weight of the aqueous acidic oxidant mixture. The amount of the halide ion source added to form the aqueous acidic oxidant mixture can be at least 1 wt.%, preferably at least 5 wt.% based on the total weight of the aqueous acidic oxidant mixture. The amount of the halide ion source added to form the aqueous acidic oxidant mixture can be up to 20 wt.%, preferably up to 15 wt.% based on the total weight of the aqueous acidic oxidant mixture. Disclosed herein, the aqueous acidic oxidant mixture comprises an acid. Various acids are compatible with the present disclosure. However preferably, the acid comprises formic acid , acetic acid, citric acid, carbonic acid, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, or combinations thereof. More preferably the acid comprises sulfuric acid, hydrochloric acid, nitric acid or combinations thereof, as good results have been achieved using these acids, as can be seen from the examples. Preferably, the acid comprises sulfuric acid, hydrochloric acid or combinations thereof. Most preferably the acid comprises sulfuric acid, as this provides particularly good results, as can be seen from the examples. The acid may be added as a concentrated acid or as a dilute solution. The skilled person will also appreciate that carbonic acid, for example, may be added directly to the aqueous acidic oxidant mixture, or, it may be formed in-situ by the addition of carbon dioxide. The preferred order of addition to form the aqueous acidic oxidant mixture is to add the acid after the remaining components. In other words, the preferred order of addition is to first combine the water, the oxidising means and the halide ion source to form an aqueous oxidant-halide mixture, and then add the acid to the aqueous oxidant-halide mixture to form the aqueous acidic oxidant mixture. The term “aqueous oxidant-halide mixture” refers to the mixture formed from combining the water, oxidant and the halide ion source. It is also preferred to stir the reaction until homogeneous, monitoring the increase in oxidation reduction potential and to form the leach before the addition of any source of metal. The leach can be regenerated after the first extraction by adding the required chemicals. Disclosed herein, the aqueous acidic oxidant mixture has a pH of less than 7. It will be understood that a pH of less than 7 refers to a pH of <7, i.e. an acidic pH. It has been found that the aqueous acidic oxidant mixture can take a variety of different acidic pH values and still provide successful extraction. For example, the aqueous acidic oxidant mixture can have a pH of greater than or equal to 0.1, greater than or equal to 0.4, or greater than or equal to 0.8. The aqueous acidic oxidant mixture can have a pH of less than or equal to 6.9, less than or equal to 6, less than or equal to 5, or less than or equal to 4. Preferably, the aqueous acidic oxidant mixture has a pH of less than or equal to 3, more preferably less than or equal to 2. As can be seen from the examples, when the aqueous acidic oxidant mixture has a pH in the range of 0.1-1.5, particularly good extraction is achieved. The skilled person will appreciate how to tailor the aqueous acidic oxidant mixture so as to achieve a particular pH. The pH is measured by standard methods known in the art, for example using a standard electronic pH meter or colour coded test strip, across temperatures ranging from 5°C to 75°C. The skilled person will appreciate that the oxidising means and the halide ion source are not necessarily mutually exclusive terms, and so may be the same or different species. For example, the oxidising means and the source of the halide ion may both be hypobromous acid (thereby providing a direct source of BrOH to the aqueous acidic oxidant mixture), and / or dissolved bromine. However preferably, the oxidising means and the halide ion source are different species. The skilled person will appreciate that the acid and the halide ion source are not necessarily mutually exclusive terms, and so may be the same or different species. For example, the source of the halide ion and the acid may both be hypobromous or hypochlorous acid. However preferably, the halide ion source and the acid are different species. The skilled person will appreciate that the acid and the oxidising means are not necessarily mutually exclusive terms, and so may be the same or different species. For example, the acid and the oxidising means may both be hypobromous or hypochlorous acid. However preferably, the acid and the oxidising means are different species. More preferably, all three of the oxidising means, the halide ion source, and the acid, are different species. The amount of metal sulfide containing material that contacts the aqueous acidic oxidant mixture can be tailored depending on e.g. the type of metal sulfide containing material, but can for example be added in amounts of 1 g to 1000 g, preferably 10 g to 800 g, more preferably 30 g to 600 g. The ratio, by weight, of metal sulfide containing material : aqueous acidic oxidant mixture can be tailored depending on e.g. the type of metal sulfide containing material, and the scale at which the method is being conducted, and can for example range from 1:0.2 to 1:10000. The ratio, by weight, of metal sulfide containing material: aqueous acidic oxidant mixture can be at least 1:0.2, preferably at least 1:1, more preferably at least 1:2. The ratio, by weight, of metal sulfide containing material : aqueous acidic oxidant mixture can be up to 1:10000, up to 1:1000, up to 1:10, preferably up to 1:8, more preferably up to 1:7. Preferably, the aqueous acidic oxidant mixture is stirred for at least 5 minutes before the aqueous acidic oxidant mixture is contacted with the metal sulfide containing material. In some embodiments, steps a) and b) occur sequentially. That is, the aqueous acidic oxidant mixture is provided and subsequently contacted with the metal sulfide containing material. In other embodiments, steps a) and b) occur simultaneously. For example, the metal sulfide containing material may be contacted with an intermediate mixture with one or more (but not all) of the aqueous acidic oxidant mixture ingredients, then the remaining ingredients of the aqueous acidic oxidant mixture are subsequently added. It will be understood that in this scenario, the aqueous acidic oxidant mixture is immediately in contact with the metal sulfide containing material upon its formation. Hence, the provision of the acidic aqueous oxidant mixture of step a), and the contacting of this mixture with the metal sulfide containing material of step b) occurs at the same time. Disclosed herein, there is the step contacting the aqueous acidic oxidant mixture with the metal sulfide containing material to extract the metal from the metal sulfide containing material and form a metal halide solution. Optionally following this, the same metal sulfide containing material may be separated from the metal halide solution and washed, preferably with a fresh mixture of the aqueous acidic oxidant mixture disclosed herein. In the instance that the metal sulfide containing material is washed with a fresh mixture of the aqueous acidic oxidant mixture disclosed herein, this will form additional metal halide solution. Disclosed herein, the method herein can be a method of extracting nickel from a nickel sulfide containing material, to extract the nickel from the nickel sulfide containing material and form a nickel halide solution. Disclosed herein, the method herein can be a method of extracting lead from a lead sulfide containing material, to extract the lead from the lead sulfide containing material and form a lead halide solution. Disclosed herein, the method herein can be a method of extracting zinc from a zinc sulfide containing material, to extract the zinc from the zinc sulfide containing material and form a zinc halide solution. The method disclosed herein has particular applicability to copper, nickel and / or zinc extraction. Therefore preferably, the method herein is a method of extracting copper, nickel and / or zinc from a copper sulfide, nickel sulfide and / or zinc sulfide containing material, to extract the copper, nickel and / or zinc from the copper sulfide, nickel sulfide and / or zinc sulfide containing material and form a copper halide, nickel halide and / or zinc halide solution. The method disclosed herein has particular applicability to copper and / or zinc extraction. Therefore preferably, the method herein is a method of extracting copper and / or zinc from a copper sulfide and / or zinc sulfide containing material, to extract the copper and / or zinc from the copper sulfide and / or zinc sulfide containing material and form a copper halide and / or zinc halide solution. As can be seen from the examples, particularly good results have been obtained for copper extraction. Therefore more preferably, the method herein is a method of extracting copper from a copper sulfide containing material, to extract the copper from the copper sulfide containing material and form a copper halide solution. Disclosed herein, there is the step of contacting the aqueous acidic oxidant mixture with the metal sulfide containing material to extract the metal from the metal sulfide containing material and form a metal halide solution. As used herein, the extraction of the metal from the metal sulfide containing material can be referred to as the leaching of the metal from the metal sulfide containing material, and the term “leach” can be used to refer to the mixture / solution used to extract the metal. The metal is extracted from the metal sulfide containing material to form a metal halide, which may then be isolated, or it may be converted into other forms of the metal in question. For example, the metal halide may be converted to another metal salt (such as metal carbonate, and / or metal hydroxide), and / or metal0. It will be understood that metal0 refers to the metal in question in an oxidation state of zero, for example copper0, nickel0, lead0 and / or zinc0, as opposed to referring to the metal in question in cation or salt form. Accordingly, the method may further comprise the step of converting the metal halide (extracted from the metal sulfide containing material) to another metal salt and / or metal0. The step of converting the metal halide to another metal salt and / or metal0 is denoted herein as step c). The skilled person will appreciate that there are various ways in which to convert the metal halide to another metal salt and / or metal0 and will be familiar with appropriate reagents and conditions. The skilled person will appreciate that there are various ways in which to convert the metal halide to metal0, metal carbonate, and / or metal hydroxide and will be familiarwith appropriate reagents and conditions. However, preferably step c) comprises the step of contacting the metal halide solution with carbon dioxide, carbon monoxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, carbonic acid, a reducing means, sodium hydroxide, potassium hydroxide, oxygen, ozone, or a combination thereof. A further benefit is provided when the method comprises the step of converting the metal halide (extracted from the metal sulfide containing material) to another metal salt (such as metal carbonate, and / or metal hydroxide), and / or metal0. Doing so allows the halide to effectively be recycled. This therefore allows for an efficient method at least in terms of use of reactants. It will be understood from this that the method disclosed herein encompasses scenarios where recycled leach is present. When step c) comprises the step of contacting the metal halide solution with carbon dioxide, carbon monoxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, carbonic acid, or a combination thereof, the metal halide is thereby converted to metal carbonate. When step c) comprises the step of contacting the metal halide solution with a reducing means, the metal halide is thereby converted to metal0. Preferably, step c) is carried out by electrowinning, thereby converting the metal halide to metal0. Electrowinning takes its usual definition in the art, and so refers to passing of an electrical current through the metal halide solution such that the metal is deposited onto a cathode via an electroplating process. Electrowinning is preferred due to reduced biproduct formation. When step c) comprises the step of contacting the metal halide solution with sodium hydroxide, potassium hydroxide, oxygen, ozone, or a combination thereof, the metal halide is converted to metal hydroxide. The skilled person will appreciate that a reducing means is a component capable of acting as an reductant, and can for example be a chemical reagent (usually referred to as an reducing agent), or a component of a system suitable for achieving reduction by electrolysis, for example a cathode connected to a power source. Preferably, the reducing means is a chemical reagent. Preferably, the reducing means is zinc, sodium metabisulfite, hydrogen gas, and / or a cathode connected to a power source. The skilled person will appreciate that a cathode is an electrode at which reduction occurs. Generally, the cathode is at least partially (or, fully) submerged in the metal halide solution. The cathode is connected to a power source which is capable of applying an electrical current such that the electrons flow towards the cathode, thereby allowing reduction (i.e. gain of electrons) to occur at the cathode. This is generally referred to as reduction by electrolysis, and so the skilled person will appreciate that the power source will in turn usually be connected to an anode. More preferably, the reducing means is zinc, sodium metabisulfite, and / or hydrogen gas. Preferably, the metal halide is converted to metal carbonate, as in this scenario the overall reaction results in consumption of carbon dioxide, resulting in yet further improved environmental credentials. Disclosed herein, the method herein can be a method of extracting nickel from a nickel sulfide containing material, to extract the nickel from the nickel sulfide containing material and form a nickel halide solution, optionally further comprising the step of converting the nickel halide to nickel0, nickel carbonate, and / or nickel hydroxide. Disclosed herein, the method herein can be a method of extracting lead from a lead sulfide containing material, to extract the lead from the lead sulfide containing material and form a lead halide solution, optionally further comprising the step of converting the lead halide to lead0, lead carbonate, and / or lead hydroxide. Disclosed herein, the method herein can be a method of extracting zinc from a zinc sulfide containing material, to extract the zinc from the zinc sulfide containing material and form a zinc halide solution, optionally further comprising the step of converting the zinc halide to zinc0, zinc carbonate, and / or zinc hydroxide. The method disclosed herein has particular applicability to copper and / or zinc extraction. Therefore preferably, the method herein is a method of extracting copper and / or zinc from a copper sulfide and / or zinc sulfide containing material, to extract the copper and / or zinc from the copper sulfide and / or zinc sulfide containing material and form a copper halide and / or zinc halide solution, optionally further comprising the step of converting the copper halide and / or zinc halide to copper0 and / or zinc0, copper carbonate and / or zinc carbonate, copper hydroxide and / or zinc hydroxide, or combinations thereof. As can be seen from the examples, particularly good results have been obtained for copper extraction. Therefore more preferably, the method herein is a method of extracting copper from a copper sulfide containing material, to extract the copper from the copper sulfide containing material and form a copper halide solution, optionally further comprising the step of converting the copper halide to copper, copper carbonate, and / or copper hydroxide. Disclosed herein, metal is extracted from the metal sulfide containing material to form a metal halide, which may be recovered and so isolated from the remaining reactants, and / or it may be converted into other forms of metal, which may then in turn be recovered and so isolated from the remaining reactants. Accordingly, the methods disclosed herein may further comprise the step of recovering the metal halide and / or may further comprise the step of recovering the other form(s) of metal to which the metal halide has been converted. It will be understood that by “recovering” it is meant that the metal species in question (i.e. the metal halide, and / or the other form(s) of metal to which the metal halide has been converted) is collected, removed, or isolated, from the reactant mix. This may be achieved by appropriate solid-liquid separation techniques (such as sieving, for example) when the metal species in question is solid (such as metal carbonate), by solvent extraction process which may or may not contain various chelates, by reverse osmosis, by the use of activated carbon, by electrowinning, or by use of one or more ion exchange resins. It will be understood that the “other form(s) of metal to which the metal halide has been converted” refers to those detailed elsewhere in the present disclosure and so can include another metal salt (such as metal carbonate, and / or metal hydroxide), metal0, or a combination thereof, and are subject to the same degrees of preference to those detailed herein. The use of ion exchange resins is a preferred means by which to recover the metal species i.e. the metal halide, and / or the other form(s) of metal to which the metal halide has been converted. As detailed elsewhere in this disclosure, such other form(s) of metal can include another metal salt (such as metal carbonate, and / or metal hydroxide), metal0, ora combination thereof. Accordingly, step b) and (when present) step c) may feature the use of resins. Ion exchange resins capture the metal species so as to isolate the metal species from the solution, allowing good recovery of the metal species from the reactant mix. The ion exchange resins may be used in the method disclosed herein together with metal sulfide containing materials that contain metal at varying levels, but are effective even when the level of metal in the metal sulfide containing material is low. When used in the method disclosed herein, the ion exchange resins are preferably comprised of an organic polymer backbone to which a series of functional groups are attached, said functional groups containing at least one heteroatom. In this preferred scenario, the resins provide improved capture of the metal species compared with capturing using activated carbon. Without wishing to be bound by theory, it is thought that the improved capture of the metal species is due to the at least one heteroatom within the series of functional groups. It is thought that the at least one heteroatom coordinates with the metal species in question, facilitating the formation of a complex between the metal species and the resin. Such resins may therefore be referred to as chelating resins. Step b) may further comprise contacting the aqueous acidic oxidant mixture with a resin, said resin preferably being an ion exchange resin comprised of an organic polymer backbone to which a series of functional groups are attached, said functional groups containing at least one heteroatom. It is thought that the use of a resin in step b) allows for the formation of a metal halide resin complex. It will be understood that the term “metal halide resin complex” refers to the species formed from the interaction between the metal halide (i.e. the metal that has been extracted from the metal sulfide containing material) and the resin. It will be understood from this that the metal halide resin complex refers to the resin with the metal halide complexed thereon or therein. In step b, the resin and the metal sulfide containing material may be added simultaneously, or sequentially. “Sequentially” meaning one after the other. For example, when the resin and the metal sulfide containing material are added to the aqueous acidic oxidant mixture sequentially, the resin can be added before (i.e. prior to), or after, the addition of the metal sulfide containing material. Accordingly, the resin can be added simultaneously with, prior to, or after, the addition of the metal sulfide containing material. The timing of these steps can be tailored at the convenience of the processing facilities. It will be appreciated that, when the resin and metal sulfide containing material are added either simultaneously or in immediate succession, the metal halide may form and then immediately react to result in the formation of the metal halide resin complex. This scenario is referred to as a “Resin in leach” process. As such, in step b, the resin and the metal sulfide containing material may be added simultaneously to the aqueous acidic oxidant mixture. Or, in step b, the resin may be added to the aqueous acidic oxidant mixture prior to the addition of the metal sulfide containing material. Or, in step b, the resin may be added to the aqueous acidic oxidant mixture after the addition of the metal sulfide containing material. The amount of resin used in step b) can vary depending on the application in question, but can for example range from 0.1 -100g per 100ml of aqueous acidic oxidant mixture. The amount of resin used in step b) can be at least 0.1g, at least 1 g, at least 2g, preferably at least 5g, per 100ml of aqueous acidic oxidant mixture. The amount of resin used in step b) can be up to 100g, up to 80g, up to 50g, preferably up to 20g, per 100ml of aqueous acidic oxidant mixture. Step c may further comprise contacting the metal halide solution with a resin, said resin preferably being an ion exchange resin comprised of an organic polymer backbone to which a series of functional groups are attached, said functional groups containing at least one heteroatom. It is thought that the use of a resin in step c) allows for the formation of a complex between the resin and the form(s) of metal to which the metal halide has been converted. As detailed elsewhere in this disclosure, such other form(s) of metal can include another metal salt (such as metal carbonate, and / or metal hydroxide), metal0, or a combination thereof. For example, when the metal halide has been converted to metal0, metal carbonate, and / or metal hydroxide, it is thought that the use of a resin in step c) allows for the formation of a metal0 resin complex, a metal carbonate resin complex, and / or metal hydroxide resin complex. It will be understood that the terms “metal0 resin complex”, “metal carbonate resin complex”, and “metal hydroxide resin complex” each refer to the species formed from the interaction between the respective metal species in question and the resin. It will be understood from this that the “metal0 resin complex”, “metal carbonate resin complex”, and “metal hydroxide resin complex” refers to the resin with the respective metal species complexed thereon or therein. In step c), the resin may be added prior to, simultaneously with, or after the conversion of the metal halide to other form(s) of metal. As detailed elsewhere in this disclosure, such other form(s) of metal can include another metal salt (such as metal carbonate, and / or metal hydroxide), metal0, or a combination thereof. The timing of these steps can be tailored at the convenience of the processing facilities. It will be appreciated that, when the addition of the resin and the conversion of the metal halide to other form(s) of metal occurs either 24 simultaneously or in immediate succession, the other form(s) of metal may form and then immediately react to result in the formation of a complex between the resin and the metal species in question (such as, for example, a metal0 resin complex, a metal carbonate resin complex, and / or metal hydroxide resin complex). In step c), the resin is preferably added simultaneously with, or after, the conversion of the metal halide to other form(s) of metal. As detailed elsewhere in this disclosure, such other form(s) of metal can include another metal salt (such as metal carbonate, and / or metal hydroxide), metal0, or a combination thereof. More preferably, the resin is added after the conversion of the metal halide to other form(s) of metal - in which case, step c may further comprise contacting the mixture of other metal form(s) of metal with a resin, said resin preferably being an ion exchange resin comprised of an organic polymer backbone to which a series of functional groups are attached, said functional groups containing at least one heteroatom, to thereby form a complex between the resin and the metal species in question. The amount of resin used in step c) can vary depending on the application in question, but can for example range from 0.1-100g per 100ml of metal halide solution, or mixture of other form(s) of metal to which the metal halide has been converted. As detailed elsewhere in this disclosure, such other form(s) of metal can include another metal salt (such as metal carbonate, and / or metal hydroxide), metal0, or a combination thereof. The amount of resin used in step c) can be at least 0.1g, at least 1g, at least 2g, preferably at least 5g, per 100ml of metal halide solution, or mixture of other form(s) of metal to which the metal halide has been converted. The amount of resin used in step c) can be up to 100g, up to 80g, up to 50g, preferably up to 20g, per 100ml of metal halide solution, or mixture of other form(s) of metal to which the metal halide has been converted. The term “ion exchange resin” takes its usual definition in the art, and so refers to a material that acts as a medium for ion exchange that is generally insoluble in aqueous mediums. It will be understood from this that the ion exchange resin is substantially insoluble in the aqueous solutions and mixtures disclosed herein, e.g. the aqueous acidic oxidant mixture, metal halide solution or mixture of other form(s) of metal to which the metal halide has been converted. By “substantially insoluble”, it is meant that less than 0.1 mg / ml of the resin dissolves in the aqueous solutions and mixtures disclosed herein (e.g. the aqueous acidic oxidant mixture, metal halide solution or mixture of other form(s) of metal to which the metal halide has been converted) at 25 °C. As used herein, definitions relating to the ion exchange resin generally refer to the features of the ion exchange resin per se, i.e. prior to its addition to the aqueous solutions and mixtures disclosed herein. After its addition, it will be understood that, depending on the pH of the medium in question, protonation or deprotonation of certain groups of the ion exchange resin may occur. The ion exchange resin is preferably a porous material. The porosity of the ion exchange resin increases the surface area available for ion exchange. Consistent with what will be understood from the term “ion exchange resin”, the ion exchange resin, when used in the method disclosed herein, is comprised of a polymer backbone (sometimes referred to as a polymer matrix), to which a series of functional groups are attached. Specifically, the ion exchange resin, when used, is comprised of an organic polymer backbone to which a series of functional groups are attached. The ion exchange resin may essentially consist of an organic polymer backbone to which a series of functional groups are attached. The ion exchange resins, when used in the method disclosed herein, are commercially available from a variety of sources, with commercially available resins including but not limited to the following, which are all ion exchange resins with polystyrene backbones functionalised with the following groups: - SEPLITE® LSC660: functionalised with guanidine groups - SEPLITE® LSC740: functionalised with thiol groups - SEPLITE® LSC710: functionalised with iminodiacetic acid groups - AMBERSEP® 21K XLT Mesh Anion Exchange Resin (CI-): functionalised with quaternary ammonium groups - Purogold™ MTA5015SO4: functionalised with quaternary ammonium groups - LEWATIT® MonoPlus TP 214: functionalised with thiourea groups - Puromet™ MTS9140: functionalised with thiourea groups - LEWATIT MP 62 WS: functionalised with tertiary amine groups - LEWATIT TP 106: functionalised with quaternary ammonium groups As used herein, the term “polymer” takes its usual definition the art and so refers to a homopolymer or copolymer formed from the polymerisation of one or more monomers. As such, this term covers e.g. linear polymers, branched polymers, and cyclic polymers. As used herein, the term “homopolymer” takes its usual definition in the art, and so refers to a polymer whose polymer chains comprise one type of monomer. As used herein, the term “co-polymer” takes its usual definition in the art, and so refers to a polymer whose polymer chains comprise two or more different types of monomers. The skilled person will appreciate therefore that the term “co-polymer” encompasses polymers that include three different types of monomers (which can at times be referred to in the art specifically as “terpolymers”). The term “block co-polymer” takes its usual definition in the art and so refers to a copolymer whose polymer chains include two or more blocks of monomers. Each block is comprised of a particular monomer type, where at least two of the blocks present comprise a different monomer type to one another. A diblock co-polymer, a tri-block copolymer, and a tetra-block copolymer, each refer to copolymers with two, three, and four monomer blocks respectively. As used herein, the term “monomer” takes its usual definition in the art and so refers to a molecular compound that may chemically bind to another monomer to form a polymer. Unless expressly stated to the contrary, any monomer referred to herein should be understood to include all enantiomers, diastereomers, racemates and mixtures thereof of the monomers in question. It will be understood that the term “polymer backbone” refers to the series of covalently bonded atoms that create a continuous molecular chain which acts as a scaffold to which the functional groups are attached. In line with the usual definition in the art, the polymer backbone is generally the longest continuous molecular chain, to which other chains and functional groups may be regarded as being pendant. It will be understood that the term “organic polymer backbone” refers to a polymer backbone that includes carbon-carbon covalent bonds. The organic polymer backbone may be crosslinked or uncrosslinked. Preferably, the organic polymer backbone is crosslinked with a crosslinking agent such as divinylbenzene, hexamethylenetetramine, a functionalized silane, isocyanate, peroxide, or combinations thereof. More preferably, the organic polymer backbone is crosslinked with divinylbenzene. The amount of crosslinker can vary, but can be for example 1 % to 50% by weight, based on the total weight of the polymer backbone and crosslinker. The organic polymer backbone can for example be polystyrene, polyvinyl toluene, poly(vinylbenzyl chloride), polyvinyl acetate, polyvinyl butyral, polyvinyl ether, polyethylene, polyurethane, or acrylonitrile butadiene styrene. Preferably, the organic polymer backbone is a vinyl polymer backbone, which will be understood as referring to a polymer backbone formed from vinyl monomers (i.e. those monomers including in their structure the formula -CH=CH2). For example, the organic polymer backbone can be polystyrene, polyvinyl toluene, poly(vinylbenzyl chloride), polyvinyl acetate, polyvinyl butyral and polyvinyl ether. More preferably, the organic polymer backbone is polystyrene. In a particularly preferred embodiment, the organic polymer backbone is polystyrene crosslinked with divinylbenzene. Disclosed herein, a series of functional groups are attached to the organic polymer backbone. It will be understood that this attachment is generally by covalent bonding to the organic polymer backbone. This attachment may be achieved by standard procedures known in the art. By “series” it is meant that there are a plurality of functional groups attached to the polymer backbone. For a given ion exchange resin, the functional groups may be the same or different. The functional groups contain at least one heteroatom. The term “heteroatom” takes its usual definition in the art, and so refers to an atom that is not carbon or hydrogen. Preferably, the heteroatom is one or more of N (nitrogen), S (sulphur), O (oxygen), and P (phosphorus). More preferably, the heteroatom is one or more of N, S, and O, more preferably one or more of N and S. It will be appreciated that, when the heteroatom is one or more of the listed options, additional heteroatoms other than those recited in this list may also be present in the functional groups. Unless expressly stated to the contrary, the atomic species given for the heteroatom are to be understood as encompassing that species irrespective of whether or not it is in a neutral state. In particular, when the series of functional groups contain N, this encompasses scenarios where the N is positively charged, for example as part of a quaternary ammonium group. Particularly preferred is when the series of functional groups includes one or more of an iminodiacetic acid group, a thiourea group, a quaternary ammonium group, a guanidine group, an amine group, and a thiol group. The skilled person will be familiar with the molecular structure implied by these groups. Within this embodiment, the functional groups of the series can be iminodiacetic acid groups, thiourea groups, quaternary ammonium groups, guanidine groups, amine groups, or thiol groups. Even more preferably, the series of functional groups includes one or more of a thiourea group, a quaternary ammonium group, and a guanidine group. Within this embodiment, the functional groups of the series can be thiourea groups, quaternary ammonium groups or guanidine groups. The functional groups disclosed herein can be attached to the polymer backbone by standard reaction procedures known in the art, with the attachment between the functional group and the backbone being located at an appropriate point of the molecular framework of the functional group, as will be appreciated by the skilled person. The term “iminodiacetic acid” refers to the formula HN(CH2CO2H)2. When the series of functional groups includes an iminodiacetic acid group, the functional groups comprise one or more of the following moieties: The term “thiourea” refers to the formula S=C(NR1R2)(NR3R4), where R1, R2, R3 and R4 may be the same or different and are each independently selected from H or an alkyl group. Preferably, R1, R2, R3 and R4 are the same or different and are each independently selected from H or a Ci-Ce alkyl group. Within this embodiment, R1, R2, R3 and R4 are the same or different and can each be independently selected from H or a C1-C3 alkyl group. More preferably, R3 and R4 are both H. When the series of functional groups includes a thiourea group, the functional groups comprise one or more of the following moieties, with R1, R2, R3 and R4 taking the same meaning and preferences as those stated above: 5           The term “quaternary ammonium” refers to the formula [NR5R6R7R8]+, where R5, R6, R7 and R8 may be the same or different and are each independently selected from H or an alkyl group. Preferably, R5, R6, R7 and R8 are the same or different and are each independently selected from H or a Ci-Ce alkyl group. More preferably, R5, R6, R7 and R8 are each an alkyl group, preferably a Ci-Ce alkyl 10 group, and may be the same or different. Preferably, R5, R6, R7 and R8 are each a C1-C3 alkyl group, and may be the same or different. When the series of functional groups includes a quaternary ammonium group, the functional groups comprise one or more of the following moieties, with R5, R6 and R7 taking the same meaning and preferences as those stated above: 15 vAAAP R7---N+---R5 The term “guanidine” refers to the formula (R9R10N)(R11R12N)C=N-R13 where R9, R10, R11, R12 and R13 may be the same or different and are each independently selected from H or an alkyl group. Preferably, the alkyl group is a Ci-Ce alkyl group, more preferably a C1-C3 alkyl group. More preferably, the term 5 “guanidine” refers to the formula HN=C(NH2)2, which the skilled person will appreciate is non-derivatised guanidine, where R9, R10, R11, R12 and R13are each H. When the series of functional groups includes a guanidine group, the functional groups comprise one or more of the following moieties, with R9, R10, 10   R11, R12 and R13 taking the same meaning and preferences as those stated above: 15 The term “thiol” refers to the formula R14-SH where R14 is an alkyl group, preferably a Ci-Ce alkyl group, more preferably a C1-C3 alkyl group. When the series of functional groups includes a thiol group, the functional groups comprise one or more of the following moieties: SH I WW' The term “amine” refers to the formula NR15R16R17, where R15, R16 and R17 may be the same or different and are each independently selected from H or an alkyl group. Preferably, R15, R16 and R17 are the same or different and are each independently selected from H or a Ci-Ce alkyl group. More preferably, R15, R16 and R17 are the same or different and are each an alkyl group, preferably a Ci-Ce alkyl group. Preferably, R15, R16 and R17are each a C1-C3 alkyl group, and may be the same or different. When the series of functional groups includes an amine group, the functional groups comprise one or more of the following moieties, with R15 and R16 taking the same meaning and preferences as those stated above: WWC R15   ^R16 As used throughout, it will be understood that the symbol “      ” denotes the end of the molecular fragment and so refers to the point at which the moieties are attached to the polymer backbone. The moieties may be attached directly to the polymer backbone e.g. by way of a direct bond, or, they may be attached via an alkyl group, such as a C1-C10 alkyl group, preferably a Ci-Ce alkyl group, more preferably a C1-C3 alkyl group. As used herein, the term “alkyl” refers to a straight or branched saturated or unsaturated alkyl group. Preferably, the alkyl group is a saturated alkyl group. More preferably, the alkyl group is a straight alkyl group. As used herein, the term "(Ca-Cb)alkyl" wherein a and b are integers refers to a straight or branched chain alkyl having from a to b carbon atoms. Thus, by way of example, a C1-C10 alkyl group refers to a group having from 1 to 10 carbon atoms, and so includes methyl, ethyl, n-propyl, isopropyl, n- butyl, isobutyl, sec-butyl, t-butyl, n-pentyl, n-hexyl, heptyl, octyl, nonyl and decyl. Meanwhile, a Ci-Ce alkyl group refers to a group having from 1 to 6 carbon atoms, and so includes methyl, ethyl, n-propyl, isopropyl, n- butyl, isobutyl, sec-butyl, t-butyl, n-pentyl, n-hexyl. The resin may be provided as a plurality of beads with a particle size distribution such that more than 95% of the particles have a diameter of 0.1 to 10mm, 0.2 to 5mm, 0.1 to 2.5mm or 0.2 to 1.5mm. The bulk density can vary, for example from 100 g / l to 2000 g / l, preferably from 200 to 900 g / l, more preferably from 500 g / l to 900 g / l, or from 600 g / l to 850 g / l. The absolute density can vary, for example from 100 to 2000 g / l, preferably from 200 to 1500, more preferably from 500 to 1200 g / l. When resins feature in the method disclosed herein, the method may further comprise the step of recovering the metal species (i.e. the metal halide, and / or the other form(s) of metal to which the metal halide has been converted) from the metal species resin complex. The skilled person will appreciate that this can be carried out by a variety of possible means. For example, the resin, complete with the complexed metal species (the metal species resin complex) can be removed from the remaining components of the method disclosed herein by appropriate solid-liquid separation techniques (such as sieving, for example), before subjecting the resin to a suitable method to separate the metal species from the resin. For example, the metal species can be recovered from the metal species resin complex by stripping, incineration, ashing or burning of the resin. The method disclosed herein may comprise the additional step of subjecting the material from which the metal has been extracted to a decontamination step, said decontamination step comprising the step of contacting the material with one or more ion exchange resins with specifics and preferred features disclosed herein. It has been found that certain functional groups, such as thiol groups, have selectivity for impurities such as arsenic, and mercury. Therefore, not only can certain resins disclosed herein be used to selectively extract metal in preference to impurities, but certain resins disclosed herein can then be used to decontaminate the material leftover from the method 5 (sometimes referred to as “tailings”), providing a “clean up” operation for the tailings leftover from the method. The method disclosed herein may be carried out at a variety of different temperatures, for example from 5-100 degrees C. The method disclosed herein may be carried out at a range if different pressures, and can for example be carried 10 out at elevated pressures in a sealed system, but more typically is carried out at atmospheric pressure. The following non-limiting Examples illustrate the invention. EXAMPLES 1-8 Examples 1-8 report results of copper extraction from a copper sulfide containing ore. The results are shown in Table 1 below, with Example 1 corresponding to “Text 1”, Example 2 corresponding to “Test 2”, and so on. The % copper extraction was assessed using fire assay and ICP (inductively coupled plasma) as follows. The amount of copper in the head ore (i.e. the ore prior to the extraction process) was measured using an industry standard fire assay, as was the amount of copper in the tails (i.e. spent ore material left over after the extraction process). The level of copper in the head ore was compared to the level of copper remaining in the tails. The bigger the difference between the level of copper in the head ore and the level of copper remaining in the tails, the better the copper extraction. Table 1 reports the difference between the level of copper in the head ore and the level of copper remaining in the tails as a % of the level of copper in the head ore (i.e. heads-tails / heads*100). Test# Cu         Ux Dre 1 §2%  ; H25O4 / H^ 50 2 8» H2SWI» SO 3 80%   ; HBr SO 4 77%   H(W SO 5 92% 25 a 88%  ; H2SO4 / S^ 25 7 88%       HBr 25 8 87%    HCWCI 25 Table 1 The full methodology of Examples 1-8 is as follows. EXAMPLE 1 Water (156) was placed into a circular bottle and sodium bromide solution in water (46%, 20.6ml), hydrogen peroxide (34%, 24.4ml) was stirred and sufficient sulfuric acid added to reduce the pH to 0.5 and the mixture stirred for 30 min until the ORP (oxidation reduction potential) reached above 650. Copper sulfide containing ore which had previously been crushed to 50 micron (50gm) was added and the reaction was stirred using a bottle roll for 60 min with samples taken at 15, 30 and 60 min. The solution was filtered and the tails were washed with 20 ml of fresh lixiviant after the initial solution had been placed to one side for analysis. The tails were then washed with water, dried and submitted for a fire assay. The solution were analyzed for copper using a calibrated ICP The results are shown in Table 1 as “Test 1”. EXAMPLE 2 Water (176ml) was placed into a circular bottle and sodium bromide solution in water (46%, 0.4ml), hydrogen peroxide (34%, 24.4ml) was stirred and sufficient sulfuric acid added to reduce the pH to 0.5 and the mixture stirred for 30 min until the ORP (oxidation reduction potential) reached above 650. Copper sulfide containing ore which had previously been crushed to 50 micron (50gm) was added and the reaction was stirred using a bottle roll for 60 min with samples taken at 15, 30 and 60 min. The solution was filtered and the tails were washed with 20 ml of fresh lixiviant after the initial solution had been placed to one side for analysis. The tails were then washed with water, dried and submitted for a fire assay. The solution were analyzed for copper using a calibrated ICP. The results are shown in Table 1 as “Test 2”. EXAMPLE 3 Water (164ml) was placed into a circular bottle and hydrobromic acid in water (48%, 13.8ml), hydrogen peroxide (34%, 24.4ml) was stirred and sufficient sulfuric acid added to reduce the pH to 0.5 and the mixture stirred for 30 min until the ORP (oxidation reduction potential) reached above 650. Copper sulfide containing ore which had previously been crushed to 50 micron (50gm) was added and the reaction was stirred using a bottle roll for 60 min with samples taken at 15, 30 and 60 min. The solution was filtered and the tails were washed with 20 ml of fresh lixiviant after the initial solution had been placed to one side for analysis. The tails were then washed with water, dried and submitted for a fire assay. The solution were analyzed for copper using a calibrated ICP The results are shown in Table 1 as “Test 3”. EXAMPLE 4 Water (177ml) was placed into a circular bottle and sodium chloride (7.4gm), hydrogen peroxide (34%, 24.4ml) was stirred and sufficient hydrochloric acid added to reduce the pH to 0.5 and the mixture stirred for 30 min until the ORP (oxidation reduction potential) reached above 650. Copper sulfide containing ore which had previously been crushed to 50 micron (50gm) was added and the reaction was stirred using a bottle roll for 60 min with samples taken at 15, 30 and 60 min. The solution was filtered and the tails were washed with 20 ml of fresh lixiviant after the initial solution had been placed to one side for analysis. The tails were then washed with water, dried and submitted for a fire assay. The solution were analyzed for copper using a calibrated ICP. The results are shown in Table 1 as “Test 4”. EXAMPLE 5 Water (156ml) was placed into a circular bottle and sodium bromide solution in water (46%, 20.6ml), hydrogen peroxide (34%, 24.4ml) was stirred and sufficient sulfuric acid added to reduce the pH to 0.5 and the mixture stirred for 30 min until the ORP (oxidation reduction potential) reached above 650. Copper sulfide containing ore which had previously been crushed to 50 micron (25gm) was added and the reaction was stirred using a bottle roll for 60 min with samples taken at 15, 30 and 60 min. The solution was filtered and the tails were washed with 20 ml of fresh lixiviant after the initial solution had been placed to one side for analysis. The tails were then washed with water, dried and submitted for a fire assay. The solution were analyzed for copper using a calibrated ICP. The results are shown in Table 1 as “Test 5”. EXAMPLE 6 Water (176ml) was placed into a circular bottle and sodium bromide solution in water (46%, 0.4ml), hydrogen peroxide (34%, 24.4ml) was stirred and sufficient sulfuric acid added to reduce the pH to 0.5 and the mixture stirred for 30 min until the ORP (oxidation reduction potential) reached above 650. Copper sulfide containing ore which had previously been crushed to 50 micron (25gm) was added and the reaction was stirred using a bottle roll for 60 min with samples taken at 15, 30 and 60 min. The solution was filtered and the tails were washed with 20 ml of fresh lixiviant after the initial solution had been placed to one side for analysis. The tails were then washed with water, dried and submitted for a fire assay. The solution were analyzed for copper using a calibrated ICP. The results are shown in Table 1 as “Test 6”. EXAMPLE 7 Water (164ml) was placed into a circular bottle and hydrobromic acid in water (48%, 13.8ml), hydrogen peroxide (34%, 24.4ml) was stirred and sufficient sulfuric acid added to reduce the pH to 0.5 and the mixture stirred for 30 min until the ORP (oxidation reduction potential) reached above 650. Copper sulfide containing ore which had previously been crushed to 50 micron (25gm) was added and the reaction was stirred using a bottle roll for 60 min with samples taken at 15, 30 and 60 min. The solution was filtered and the tails were washed with 20 ml of fresh lixiviant after the initial solution had been placed to one side for analysis. The tails were then washed with water, dried and submitted for a fire assay. The solution were analyzed for copper using a calibrated ICP The results are shown in Table 1 as “Test 7”. EXAMPLE 8 Water (177ml) was placed into a circular bottle and sodium chloride (7.4gm), hydrogen peroxide (34%, 24.4ml) was stirred and sufficient hydrochloric acid added to reduce the pH to 0.5 and the mixture stirred for 30 min until the ORP (oxidation reduction potential) reached above 650. Copper sulfide containing ore which had previously been crushed to 50 micron (25gm) was added and the reaction was stirred using a bottle roll for 60 min with samples taken at 15, 30 and 60 min. The solution was filtered and the tails were washed with 20 ml of fresh lixiviant after the initial solution had been placed to one side for analysis. The tails were then washed with water, dried and submitted for a fire assay. The solution were analyzed for copper using a calibrated ICP. The results are shown in Table 1 as “Test 8”. EXAMPLE 9 An aqueous acidic oxidant mixture was provided, and was contacted with 4 different ore samples. The samples were desiccated to dryness (friable) and pulverized to -150 mesh (105 micron). Samples were analyzed in triplicate with pyro-metallurgical methods and acid digestion to determine the quantity of metals per sample. Quantity of gold was analyzed utilizing fire assay methods with spectrometry instrument finish (ICP-OES). Quantity of other metals and sulfur content utilized acid digestion methods with ICP-OES instrument analysis. All samples were analyzed prior to testing to determine base line readings for the various elements as described above. Portions of each sample were then subjected to various conditions utilizing the aqueous acidic oxidant mixture to determine the extractive quality of the leach on the elements in the samples. Samples were leached at 23° C (room temperature) for a period up to 60 minutes with sampling at 20 minute intervals. Agitation was accomplished during the leach cycle using horizontal rolling containers with baffles. Several variations of the aqueous acidic oxidant mixture were utilized to optimize results on the various samples. Aliquots of the aqueous acidic oxidant mixture were tested at each interval for economic values and leach conditions of pH, ORP, and temperature. Aqueous samples were then analyzed with spectrophotometry (ICP) and reported below. Tailings from the process disclosed herein were then re-assayed for remaining values. Quality control measures were monitored and met minimum guidelines for the process disclosed herein. The results are shown in tables 2 and 3 below: Sample ID Sample as received (PPM) #2 Raw ere overflow of cyclone (feed to lead flotation) Sufur       Lead        Zinc        Gold 51,443       1,061       31,582       0.218 Sample after Cycladex leach (PPM) Sufur        Lead         Zinc         Gold 23,869         523       20.,225     0.194 Net Loss from 60 min leach cycle 53.6% 50.7% 36.0% 11.0% Sample ID Sample as received (PPM) #3 Tailings of Lead (Feed of zinc flotation) Sufur ; Lead ; Zinc ; Gold 53,954 s        650 ;     31,615 <   0.143 Sample after Cycladex leach (PPM) Sufur 32,803 Lead 192 Zinc 19,199 Gold 0.096 Net Loss from 60 min leach cycle 39.2%   ?   70.5% s 39.3% s 32.8% Sample ID Sample as received (PPM) Sufur Lead Zinc Gold 30Jio 296 1,581 0146 #4 Tailings of Zinc Sample after Cycladex leach (PPM) Sufur Lead Zinc Gold 24,767 125 638 0.102 Net Loss from 60 mtn leach cycle 19.4% 57.8% 59.6% 30.1% Sample ID Sample as received (PPM) Sufur Lead Zinc Gold 53,769 429 1,614 0.262 Sample after Cycladex leach (PPM) #5 Tailings from the Dam in 2022 Sufur Lead Zinc Gold 47,506 196 469 0.262 Net Loss from 60 mtn leach cycle 11.6% 54.3% 70.9% 0.0% Table 3 As shown by Tables 2 and 3, the results are favorable for both time expended and the quantity of elements that were extracted from the four ore samples that were 5 tested. Accordingly, tables 2 and 3 demonstrate the beneficial results provided by the method disclosed herein for lead and zinc. EXAMPLE 10 A series of aqueous acidic oxidant mixtures were provided and were contacted with a copper ore. The results are shown in Figure 1. As can be seen, all mixtures gave beneficially high Cu % extraction, with best extraction achieved using sulfuric 5 acid, lower pHs, and higher halide concentrations. EXAMPLE 11 A series of aqueous acidic oxidant mixtures with a pH of 0.5 were formulated and contacted with a copper ore. The NaCI concentrations were varied from 2-6.5 wt.%, the temperature of the mixture was varied from 30-80°C, and the contact 10 time was varied from 15-45 minutes. The copper extraction was determined using ICP analysis of the solutions, and the results are shown in Table 4 below. Extraction levels above 70% were observed for all of the tested mixtures. Test Concentration of NaCI (wt.%) Temperature (°C) Time (min) Extraction (%) 1 6.5 30 15 92.7 2 2 80 15 81.3 3 6.5 80 15 82.8 4 6.5 30 45 91.6 5 2 80 45 84.3 6 6.5 80 45 85 7 4.25 55 30 98.9 8 4.25 55 30 92.3 9 2 55 30 87.2 10 4.25 30 30 74.6 11 4.25 80 30 98 12 4.25 55 15 99.2 13 4.25 55 45 97.8 14 4.25 55 30 98.1 15 4.25 55 30 91 Table 4 EXAMPLE 12 A series of aqueous acidic oxidant mixtures with varying acid type, temperature, 5 halide mix and pH were formulated and contacted with a copper ore with varying run times. The halide concentration was kept constant. The copper extraction was determined using ICP analysis of the solutions, and the results are shown in Table 5 below. Extraction levels above 70% were observed for all of the tested mixtures. Test PH Temp (°C) Cl Frac1 Acid2 Time (min) Extraction3, (%) 1 0.5 40 0.5 H 60 89.1 2 0.5 40 1.0 H 30 86.9 3 1.0 40 0.5 S 60 88.8 4 1.0 40 1.0 S 30 94.8 5 0.5 80 1.0 S 60 100.7 6 0.5 80 0.5 S 30 100.6 Table 5 10 1 Cl Frac = fraction of total halide in the form of Cl (1.0 = 100% Cl, 0.5 = 50% Cl + 50% Br) 15   2 Acid: H = HCI, S = H2SO4 3 Extraction calculated based on average head assay

Claims

1. A method of extracting metal from a metal sulfide containing material comprising the steps of:a) providing an aqueous acidic oxidant mixture comprising water, an acid, an oxidising means, and a halide ion source, wherein the aqueous acidic oxidant mixture has a pH of less than 7;wherein the oxidising means comprises hydrogen peroxide, ozone, oxygen, chlorine, bromine, iodine, hypochlorous acid, hypobromous acid, hypoiodous acid, a hypochlorite salt, a hypobromite salt, a hypoiodite salt, a percarbonate salt, a persulfate salt, a permanganate salt, an anode connected to a power source, or combinations thereof;b) contacting the aqueous acidic oxidant mixture with the metal sulfide containing material to extract the metal from the metal sulfide containing material and form a metal halide solution;wherein the metal comprises copper, nickel, lead, zinc, or combinations thereof.

2. The method of claim 1, wherein the acid comprises, acetic acid, citric acid, carbonic acid, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, or combinations thereof.

3. The method of claim 1, wherein the acid comprises sulfuric acid, hydrochloric acid, nitric acid or combinations thereof.

4. The method of claim 1, wherein the acid comprises sulfuric acid.

5. The method of any preceding claim, wherein the aqueous acidic oxidant mixture has a pH in the range of 0.1-6.9.

6. The method of any preceding claim, wherein the aqueous acidic oxidant mixture has a pH in the range of 0.8-6.9.

7. The method of any preceding claim, wherein the aqueous acidic oxidant mixture has a pH less than or equal to 6, preferably less than or equal to 5, more preferably less than or equal to 4.

8. The method of any preceding claim, wherein the oxidising means comprises hydrogen peroxide, ozone, a percarbonate salt, a persulfate salt, a permanganate salt, or combinations thereof.

9. The method of any preceding claim, wherein the oxidising means comprises hydrogen peroxide.

10. The method of any preceding claim, wherein the halide ion source comprises a bromide ion source, a chloride ion source, an iodide ion source, or combinations thereof.

11. The method of any preceding claim, wherein the halide ion source comprises a bromide ion source, a chloride ion source, or combinations thereof.

12. The method of any preceding claim, wherein the halide ion source comprises a bromide ion source.

13. The method of any preceding claim, wherein the halide ion source is at least one metal halide, said metal being lithium, potassium, sodium, calcium, or combinations thereof.

14. The method of any preceding claim, wherein the halide ion source is at least one alkali metal halide, said alkali metal being lithium, potassium, sodium, or combinations thereof.

15. The method of any preceding claim, further comprising the step of:c) converting the metal halide to metal0, metal carbonate, and / or metal hydroxide.

16. The method of claim 15, wherein the halide is subsequently recycled for further use.

17. The method of any one of claims 15-16, wherein step c) comprises the step of contacting the metal halide solution with carbon dioxide, carbon monoxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, carbonic acid, a reducing means (such as zinc, sodium metabisulfite, hydrogen gas, and / or a cathode connected to a power source), sodium hydroxide, potassium hydroxide, oxygen, ozone, or combinations thereof.

18. The method of any one of claims 15-17, wherein step c) comprises the step of contacting the metal halide solution with carbon dioxide, carbon monoxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, carbonic acid, or combinations thereof, thereby converting the metal halide to metal carbonate.

19. The method of any one of claims 15-18, wherein step c) comprises the step of contacting the metal halide solution with a reducing means (such as zinc, sodium metabisulfite, hydrogen gas, and / or a cathode connected to a power source), thereby converting the metal halide to metal0.

20. The method of any one of claims 15-19, wherein step c) is carried out by electrowinning, thereby converting the metal halide to metal0.

21. The method of any one of claims 15-20, wherein step c) comprises the step of contacting the metal halide solution with sodium hydroxide, potassium hydroxide, oxygen, ozone, or combinations thereof, thereby converting the metal halide to metal hydroxide.

22. The method of any one of claims 1-14, further comprising the step of recovering the metal halide.

23. The method of any one of claims 15-21, further comprising the step of recovering the metal0, metal carbonate, and / or metal hydroxide.

24. The method of any preceding claim, wherein step b further comprises contacting the aqueous acidic oxidant mixture with a resin, said resin being an ion exchange resin comprised of an organic polymer backbone to which a series offunctional groups are attached, said functional groups containing at least one heteroatom.

25. The method of any one of claims 15-21, wherein step c further comprises contacting the metal halide solution with a resin, said resin being an ion exchange resin comprised of an organic polymer backbone to which a series of functional groups are attached, said functional groups containing at least one heteroatom.

26. The method of any one of claims 15-21, wherein step c further comprises contacting the metal0, metal carbonate, and / or metal hydroxide with a resin, said resin being an ion exchange resin comprised of an organic polymer backbone to which a series of functional groups are attached, said functional groups containing at least one heteroatom.

27. The method of any preceding claim, wherein the metal sulfide containing material comprises an ore, a subsurface brine, a battery, or combinations thereof.

28. The method of any preceding claim, wherein the metal sulfide containing material comprises an ore.

29. The method of any preceding claim, wherein the metal comprises copper, such that said method is a method of extracting copper from a copper sulfide containing material, to extract the copper from the copper sulfide containing material and form a copper halide solution.

30. The method of any preceding claim, wherein steps a) and b) occur sequentially or simultaneously.