Process for recovering a target metal

Abstract

The present invention relates to a process of recovering one or more target metals from a feedstock using a molten salt. The process comprises providing a first composition as a molten salt, said molten salt comprising a solubilising salt, a reductant and a target metal and processing the first composition to form a solid comprising the target metal.

Description

[0001] PROCESS FOR RECOVERING A TARGET METAL

[0002] BACKGROUND OF THE INVENTION

[0003] The present invention relates to a process of recovering one or more target metals from a feedstock using a molten salt. The target metal is preferably recovered as a metal hydroxide, metal carbonate, metal phosphate, metal oxide, metal oxyhydroxide, a metal, or combinations thereof, and typically derives from a feedstock, for example from a waste lithium-ion battery material and / or waste magnetic materials, such as AINiCo.

[0004] Industrial waste often comprises valuable metals, which it is advantageous to recover and recycle. Typically, however, industrial waste does not comprise only said valuable metals and may also comprise organic components such as carbon-based materials, polymers such as binders or plastics, and other metals that are less valuable.

[0005] It is therefore desirable to be able to separate valuable metals in industrial waste in order to recover said metals with high yield and sufficient purity for re-use.

[0006] Known processes for recovering valuable metals from industrial waste include pyro-and hydrometallurgy, both of which require high temperature steps. In addition, energy- and time-intensive pretreatments are often required in order to remove unwanted organic components. For example, known battery recycling processes such as pyrometallurgy require a heat pre-treatment step to remove electrolytes often comprise a pyrolysis step above 700 °C to remove plastic components.

[0007] Hydrometallurgical process also often requires a large number of reagents such that the chemical complexity of the system is high. This means that developing a hydrometallurgical process requires significant R&D investment, and recovery of a valuable metal may require multiple processing steps.

[0008] In addition, industrial waste often comprises mixtures of valuable metals, which are preferably recovered in isolation. Known processes provide poor selectivity and / or yield of metals from mixtures of metals.

[0009] Accordingly, it is desirable to provide an efficient process for recovering valuable metals from industrial waste that requires less energy than known processes.It is also desirable to provide a process that does not require time-consuming pretreatment steps to separate out unwanted components of the waste, and that provides good selectivity and separation of metals from amongst mixtures of similar metals. In particular, it is desirable to provide a process that is efficient for recovering lithium.

[0010] Finally, it is also desirable to provide a process that is scalable and can easily and safely be integrated into industrial facilities.

[0011] BRIEF DESCRIPTION OF THE INVENTION

[0012] The disclosure relates to a process for recovering of one or more target metals using a molten salt.

[0013] The process of the disclosure comprises:

[0014] i. Providing a first composition as a molten salt, said molten salt comprising a solubilising salt, a reductant and a target metal; and

[0015] ii. Processing the first composition to form a solid comprising the target metal;

[0016] and

[0017] iii. Recovering the target metal.

[0018] DETAILED DESCRIPTION OF THE INVENTION

[0019] The first composition is a molten salt, comprising a solubilising salt, a reductant and a target metal.

[0020] Molten salt

[0021] The process of the disclosure comprises a molten salt. The purpose of the molten salt is to dissolve the target metal in the first composition such that it can be recovered.

[0022] In the context of the disclosure, a molten salt composition (e.g. the first composition) or a composition comprising a molten salt may also be referred to as "a melt" or "the melt".

[0023] Molten salts are salts which are liquid. Typically, molten salts become liquid at temperatures above room temperature and at atmospheric pressure. Molten salts are useful process chemicals, enabling dissolution, reaction and separation of target species, such as target metals.An embodiment of the disclosure relates to the process as described herein wherein the molten salt is a solvent in step (i).

[0024] In the context of the disclosure, the term "solvent" refers to a liquid component, such as a molten salt, that can solvate or dissolve other substances, such as a target metal.

[0025] When the molten salt is a solvent, it is used in excess.

[0026] In the context of the disclosure, "excess" may be defined as a composition wherein the solvent is provided in an amount such as to completely cover the surface of the solid components in the first composition.

[0027] Preferably, the molten salt is provided in an amount sufficient to completely cover the surface of the target metal and / or reductant in the first composition.

[0028] Preferably, the first composition comprises a wt% molten salt of 20 wt% or more, such as from 30 wt% or more, 40wt% or more, 50wt% or more or 60wt% or more.

[0029] The weight ratio of molten salt:solid material before formation of the first composition may be 1:1 to 100:1. Preferably, the weight ratio molten salt:solid material before formation of the first composition is 2:1 to 100:1 of, for instance the weight ratio molten salt:solid material before formation of the first composition is from 3:1 to 75:1, from 5:1 to 50:1, from 10:1 to 40: 1 or from 15: 1 to 30:1 of molten salt : solid material.

[0030] In some embodiments, "solid material" refers to the materials that retain their solid structure in the molten salt. In other words, the solid material corresponds to the solids which do not fully dissociate into mobile (e.g. ionic) components in the molten salt. The solid material may correspond to the reductant, the target metal, or preferably to both. In some embodiments wherein the target metal and / or reductant are provided in the form of a feedstock, "solid material" may also refer to the feedstock. In some embodiments, the "solid material" is a feedstock according to the disclosure. Feedstocks according to the disclosure comprise a target metal in solid form, however once contacted with a molten salt, the target metal may dissolve.

[0031] Accordingly, as used herein, the term "feedstock" refers to a composition comprising one or more target metals intended for recovery. The feedstock may be a wastematerial, such as battery waste material, or it may be any other suitable source of target metals, such as a magnetic waste material.

[0032] In some embodiments, the waste material feedstock may be described as a low purity feedstock. In the context of the disclosure, a "low purity feedstock" refers to a feedstock wherein the target metal content is less than 50 wt% of the total feedstock, such as less than 40 wt%, less than 30 wt%, or less than 20 wt%. Low purity feedstocks may comprise significant amounts of non-target components such as carbon, plastics, binders, electrolyte residues, or other metallic or non-metallic species. Examples of low purity feedstocks include black mass derived from battery waste that has not undergone extensive purification or separation steps prior to processing.

[0033] Suitable black mass includes lithium-ion battery black mass or sodium-ion black mass.

[0034] The black mass may be Li-depleted black mass, i.e. lithium-ion battery black mass that has been processed to reduce or remove the lithium.

[0035] In some aspects, the feedstock may also comprise a reductant, for example when the feedstock is derived from battery waste comprising conductive carbon materials. The feedstock may comprise electrode materials such as cathode materials, and may include materials such as Lithium Nickel Manganese Cobalt Oxide, Lithium Nickel Cobalt Aluminium Oxide, Lithium Manganese Oxide, Lithium Iron Phosphate, Lithium Cobalt Oxide, Lithium-Manganese-Iron-Phosphate, or combinations thereof.

[0036] Accordingly, the feedstock may be a polymetallic compound, which may be defined as a chemical compound that contains two or more different metal elements within the same molecular or crystalline structure.

[0037] The feedstock may be a magnetic waste material, such as discarded permanent magnets, iron-based scrap, and magnetic components from discarded electronics, which pose environmental risks if not properly recycled.

[0038] The feedstock may comprise magnetic materials such as AINiCo. AINiCo is a family of iron alloys which, in addition to iron, are composed primarily of aluminium (Al), nickel (Ni), and cobalt (Co). They may also comprise copper and titanium. AINiCo alloys are ferromagnetic and are used to make permanent magnets.In some embodiments, the feedstock and a solubilising salt are first mixed, and the molten salt of the first composition is formed by heating said mixture. In some embodiments, the feedstock may be added to the solubilising salt. Alternatively, the solubilising salt may be added to the feedstock.

[0039] In such embodiments, the weight ratio of solubilising salt:feedstock before formation of the first composition is from 2: 1 to 100:1, for instance the weight ratio of solubilising salt: feedstock before formation of the first composition is from 3:1 to 75:1, from 5:1 to 50:1, from 10: 1 to 40: 1 or from 15:1 to 30:1.

[0040] Preferably, the first composition comprises a weight ratio of 1.2:1 to 50:1 of molten salt:target metal for instance from 1.5:1 to 35: 1, from 2.5:1 to 25: 1, from 5: 1 to 20: 1 or from 7.5:1 to 15:1 of molten salt:target metal.

[0041] In embodiments wherein the target metal is derived from a feedstock, the weight ratio of solubilising salt to feedstock may differ from the weight ratio of solubilising salt to target metal. This is because the feedstock may comprise components other than the target metal, such as oxygen, phosphorus, carbon, or other metallic or non-metallic species. Accordingly, the effective weight ratio of solubilising salt to target metal may be higher than the weight ratio of solubilising salt to feedstock.

[0042] For example, when the feedstock is a cathode active material derived from battery waste, the target metal content of the feedstock may vary depending on the cathode chemistry. See Table 1 of the present disclosure for example amounts of metals in common black mass compositions.

[0043] In some embodiments, a weight ratio of solubilising salt to feedstock of from 1:1 to 20:1, such as from 5:1 to 10:1 may provide an effective weight ratio of solubilising salt to target metal of from approximately 10:1 to approximately 200:1, depending on the concentration of the target metal in the feedstock. For instance, when the target metal is a transition metal such as cobalt, nickel, or iron, the effective weight ratio of solubilising salt to target metal may be from approximately 10:1 to approximately 30:1. When the target metal is lithium, the effective weight ratio of solubilising salt to target metal may be from approximately 100:1 to approximately 200:1 due to the lower concentration of lithium in typical cathode active materials.

[0044] In some embodiments, the weight ratio of solubilising salt to feedstock may be selected based on the target metal to be recovered. For instance, a lower weight ratio ofsolubilising salt to feedstock may be suitable when the target metal is present in low concentration in the feedstock, whereas a higher weight ratio may be preferred when the target metal is present in higher concentration. In some cases, a weight ratio of solubilising salt to feedstock of from 5:1 to 10:1 may be suitable for recovering both transition metals and lithium from a single feedstock comprising cathode active material.

[0045] Preferably, the weight ratio of solubilising salt to feedstock before formation of the first composition is from 2:1 to 100:1, for instance from 3:1 to 75:1, from 5:1 to 50:1, from 10:1 to 40:1 or from 15:1 to 30:1. Suitably, the weight ratio of solubilising salt to feedstock may be from 4:1 to 15:1, for instance from 5:1 to 12:1, or from 8:1 to 11:1. Suitably, the weight ratio of solubilising salt to feedstock may be approximately 5:1, approximately 10:1, or approximately 15:1. The selection of an appropriate weight ratio may depend on factors such as the composition of the feedstock, the concentration of target metal in the feedstock, the density of the solubilising salt and the desired degree of dissolution of the target metal in the molten salt.

[0046] Preferably, the mole ratio of solubilising salt to feedstock before formation of the first composition is from 5: 1 to 500:1, for instance from 10: 1 to 400:1, from 20:1 to 300:1, from 30:1 to 200:1 or from 40:1 to 150:1. Suitably, the mole ratio of solubilising salt to feedstock may be from 25:1 to 100:1, for instance from 30:1 to 80:1, or from 40:1 to 60: 1. Suitably, the mole ratio of solubilising salt to feedstock may be approximately 25:1, approximately 50:1, or approximately 75:1. The mole ratio may be calculated based on the molecular weight of the solubilising salt and the average molecular weight of the feedstock components. In embodiments wherein the feedstock comprises a cathode active material, the mole ratio of solubilising salt to feedstock may be higher than the weight ratio due to the relatively low molecular weight of typical solubilising salts such as alkali metal hydroxides compared to the molecular weight of cathode active materials.

[0047] Preferably, the volume ratio of the solubilising salt to feedstock is such that the solubilising salt completely covers the feedstock material. The purpose of selecting a volume ratio such that the feedstock material is completely covered is to limit the contact of target metal and / or reductant with any oxygen or reactive gases in the atmosphere.

[0048] In a particular embodiment, the volume of solubilising salt to black mass (or other waste feedstock) is from around 0.5 litres of solubilising salt to 1kg of black mass. Forinstance, 0.4 to 0.6 litres of solubilising salt to 1kg of black mass, such as from 0.4 to 0.8 litres of solubilising salt to 1kg of black mass or 0.4 to 1 litres of solubilising salt to 1kg of black mass.

[0049] Providing the molten salt as a solvent ensures a good interaction between it and the target metal such that a complete reaction can be obtained, often without significant mixing or agitation. Providing the molten salt as a solvent may therefore result in more complete dissolution of the target metal and / or result in more complete recovery and / or a shorter reaction time.

[0050] Most preferably, the molten salt is provided in an amount sufficient to limit the contact of target metal and / or reductant with any oxygen or reactive gases in the atmosphere.

[0051] Providing a first composition wherein the molten salt is a solvent that limits oxygen contact with the target metal and / or the reductant provides easier reduction and thus recovery of the target metal.

[0052] Without wishing to be bound by theory, when oxygen is in contact with the components of the first composition, the reductant may become oxidised. For instance, when the reductant is graphite, the graphite may react with oxygen to produce CO2 as opposed to the reductant reacting with the target metal.

[0053] Moreover, in such systems, even if the target metal is reduced by the reductant, it is likely to form a metal oxide rather than a metal, making recovery more difficult.

[0054] Providing a molten salt not only facilitates conversion of the target metal to a suitable species for recovery, the molten salt may also act as a barrier to oxygen which can allow for reduction of the target metal at a lower temperature or after a shorter period of time.

[0055] A system comprising oxygen reduces the efficiency of target metal reduction and is therefore associated with a less efficient and less economical process of target metal recovery.

[0056] Known process, such as hydroxide-assisted roasting typically fail to provide a sufficient barrier to oxygen and therefore also fail to provide these benefits.An alternative option for limiting the reactive gas (e.g. oxygen) in the environment is to actively adjust the gas environment, for instance by performing the process in an inert environment. However, control of the atmosphere limits the design and operation of the processing equipment, particularly for continuous production processes. Achieving a low oxygen via the molten salt of the first composition is therefore preferred, due to increased simplicity and an improved ability to scale up the process.

[0057] Molten salts comprising a metal hydroxide such as an alkali metal hydroxide are particularly effective at providing an oxygen barrier and are therefore particularly preferred in embodiments wherein contact with oxygen is detrimental to the recovery of a target metal.

[0058] To form the molten salt, the temperature may be held at a temperature above the salt's melting temperature for a set duration.

[0059] In some embodiments, preparing the molten salt may comprise ramping the temperature slowly, or in stages in order to allow the molten salt to equilibrize.

[0060] This heating may be performed in air, or the atmosphere may be controlled with the partial pressures of gases controlled at compositions which may adjust the acidity or redox potential of the molten salt. Solid or liquid additives (such as acids, bases, reducing agents or oxidising agents) may also be added to the salt during this heating step.

[0061] Preferably, the temperature of the first composition is in the range from 100°C to 1300°C, from 170°C to 1300°C, from 200°C to 1000°C, from 250°C to 800°C, from 300°C to 750°C, from 350°C to 700°C, from 400°C to 650°C, from 100°C to 650°C, from 170°C to 650°C, from 200°C to 650°C or from 400 to 650°C.

[0062] Preferably, the temperature of the first composition is maintained for from 1 to 20 hours, for instance from 1 to 6 hours, from about 1 to 3 hours, from 2 to 19 hours, from 2 to 18 hours, from 3 to 12 hours, from 4 to 17 hours, from 6 to 16 hours, from 7 to 15 hours, from 8 to 14 hours, from 9 to 13 hours or for around 12 hours.

[0063] In an embodiment, the temperature of the first composition is maintained for less than 6 hours.The temperature required to obtain the desired level of reduction may be higher in embodiments wherein the temperature of the first composition is maintained only for a short duration. Conversely, a lower temperature may be selected if a longer duration is used.

[0064] The heating source may or may not be in contact with the molten salt. It is preferred that the heating source is not in contact with the molten salt. Such means include heating coils or heating elements in contact with the external face of the vessel. Radiative heating methods may also be used.

[0065] The heating source may also be in contact with the molten salt. Such means include immersion heating elements or electrodes capable of forming an electric arc.

[0066] Heat may also be provided by mixing the solid salt with water.

[0067] It is preferred that a means of providing insulation to minimise heat losses is implemented.

[0068] The process of solubilising a target metal in a molten salt may change the properties of the salt. As materials dissolve within the molten salt, the composition will change and consequently the melting point will change. Depending on the species dissolved, the melting point may increase or decrease. For example, increasing the Li content is likely to decrease the melting point of the system up to a certain concentration, before increasing it again.

[0069] Accordingly, the temperature of the molten salt required for its function as a solvent (i.e. to dissolve the target metal) may vary throughout the process.

[0070] A target metal in a molten salt will have a thermodynamic tendency to form a preferred species depending on the properties of the salt and environment. Parameters such as temperature, pressure, acidity and redox potential can be adjusted to change the thermodynamically preferred state of the species. Accordingly, molten salts can be used to transform a target metal into a metal species such that the metal species can be recovered.

[0071] Formation of the molten salt may comprise agitation. For instance, the molten salt may be stirred, vibrated, shaken, inverted or churned during formation.The molten salt may be prepared in any suitable receptacle. The receptable itself may also incorporate a means of heating the salt and controlling the temperature, or heat may be supplied by an external device. For example, the receptacle could be a crucible which is placed inside a furnace, or the receptacle could be a reactor vessel equipped with a heating source.

[0072] The receptacle may have a lid or the receptacle or its container may be sealed or have a means of sealing. The composition of the gas phase in contact with the salt may be controlled prior to sealing. The receptacle or its container may have an inlet or outlet for gases. A controlled flow of cover gas with a controlled composition may be implemented. The temperature of the gas inlet may be controlled.

[0073] The receptacle may have a means to introduce solid material such as feedstock material, chemical additives, or additional salt. These means may incorporate an airlock to maintain the atmosphere in contact with the receptacle.

[0074] The receptacle may have a means of sampling material, for example to be used for measurement of the acidity of the molten salt or analysis of the salt composition. The receptacle / system may have monitoring means, such as:

[0075] • Methods of measuring temperature, such as thermocouples or infrared thermometer.

[0076] • Methods of measuring redox potential, such as a three-electrode system. • Methods of measuring acidity, such as an electrochemical measurement system configured to measure the concentration of water or oxide ions in the molten salt.

[0077] • Methods of measuring pressure.

[0078] These monitoring systems may be retractable and / or replaceable.

[0079] The receptacle may have a means for removing or transferring the molten salt. For example, the receptacle may have a tap with a valve at its bottom section, enabling salt to be drained from the receptacle by gravity. Alternatively, a tube may be inserted into the receptacle towards the bottom section of the receptacle enabling molten salt to be removed from the receptacle by reducing the pressure in the tube relative to the pressure of the molten salt.The receptacle may have a means for agitating the molten salt. This could be a retractable stirring device, for example with a propeller shaped end. Alternatively, a gas could be sparged into the salt, possibly with a means of dispersing the gas, or the molten salt could be circulated by natural or forced convection.

[0080] The receptacle / system may also have a means of cooling.

[0081] Solubilising salt

[0082] The first composition of the disclosure comprises a solubilising salt. In the context of the disclosure, a solubilising salt is a salt that dissolves the target metal. The solubilising salt forms part of the molten salt in step (i) of the process as defined herein.

[0083] Any suitable solubilising salt may be used.

[0084] An example of a solubilising salt is a metal hydroxide. Preferably the first composition comprises a metal hydroxide. Molten hydroxides are typically regarded as very corrosive and are therefore highly effective solvents.

[0085] The metal hydroxide may be any suitable metal hydroxide. Preferably the metal hydroxide is a hydroxide of an alkali metal, e.g. lithium, sodium, potassium, caesium or rubidium hydroxide, or mixtures thereof. The metal hydroxide may also be a hydroxide of an earth alkaline metal, e.g. calcium or magnesium. Likewise, the metal hydroxide may comprise hydroxides of different metals.

[0086] In one embodiment, the metal hydroxide is selected from the group comprising LiOH, NaOH, KOH, CsOH and RbOH, such as NaOH, such as NaOH-KOH, such as LiOH-KOH, such as LiOH-NaOH-KOH. In the context, the nomenclature "NaOH-KOH" is used to refer to a molten salt comprising a mixture of NaOH and KOH. In a preferred embodiment, the metal hydroxide comprises KOH.

[0087] Metal hydroxides are cheap and abundant chemicals, especially when compared to other typical components of molten salts such as alkali fluorides, alkali chlorides, alkali nitrates and alkali carbonates. Advantageously, when metal hydroxide is selected as the solubilising salt, challenging impurities, such as fluoride and chloride, in the recovered product can be avoided.An embodiment of the disclosure relates to a first composition comprising more than one solubilising salt species. That is, the first composition comprises a molten salt that is a mixture.

[0088] In one embodiment, the first comprises two solubilising salts in a mol% ratio such as 30-70:30-70, for instance 40-60:40-60, 45-55:45-55 or 51:49.

[0089] In one embodiment, the first composition comprises two solubilising salts in a mol% ratio such as 50-90: 10-50, for instance 65-75:25-35, or 70:30.

[0090] In one embodiment, the first composition comprises two solubilising salts in a mol% ratio such as 65-75:25-35, for instance 69:31.

[0091] In one embodiment, the first composition comprises three solubilising salts in a mol% ratio such as 1-99:1-99:1-99 mol%, or for instance 20-60:20-60:0-40.

[0092] Providing a mixture of molten salts, for instance, a mixture of two, three or more salts, may result in modification of the properties of the molten salt. For instance, mixtures of molten salts may have a lower melting point of the individual molten salts comprised in the mixture.

[0093] For example, the melting points of LiOH, NaOH, and KOH are often reported as 462°C, 318°C and 410°C respectively. When mixed, the melting point of the resultant metal hydroxide mixture is reduced compared to the pure individual salts.

[0094] When mixed in ratios that form their lowest melting eutectics, LiOH-NaOH has a melting point of 210°C, LiOH-KOH has a melting point of 226°C and NaOH-KOH has a melting point of 170°C. This enables these molten salts to be used as process chemicals at relatively low temperatures, minimising the energy required for carrying out these processes. In some embodiments, it may be preferred not to use a eutectic composition, due to e.g. differences in thermophysical properties such as heat capacity or cost of the components.

[0095] A preferred embodiment of the disclosure relates a process according to the disclosure wherein the first composition comprises a mixture of solubilising salts.Preparation of a first composition of a mixture of solubilising salts may require the mixture to be heated close to the melting point of at least one of the components to enable the other component to mix into the liquid phase.

[0096] Preferably the mixture comprises at least one alkali metal hydroxide.

[0097] Alkali hydroxides have relatively low melting points, decompose at higher temperature (than e.g. alkaline earth hydroxides such as Mg(OH)2 decompose to metal oxides and water before reaching their melting point), and have a low viscosity.

[0098] The mixture of salts may comprise more than one alkali metal hydroxide, or the mixture may comprise an alkali metal hydroxide and another salt species.

[0099] For instance, an embodiment of the disclosure relates to a first composition comprising a metal hydroxide and a metal carbonate.

[0100] Another embodiment of the disclosure relates to a first composition comprising more than one metal hydroxide.

[0101] Preferred mixtures of molten salts comprising an alkali metal hydroxide may therefore include an alkali metal hydroxide and at least one of M-OH, MOH-Mg(OH)2, MOH-M2CO3, MOH-MX, where M is an alkali metal and X is a halide.

[0102] Particularly preferred mixtures of molten salts comprising at least one alkali metal hydroxide comprises NaOH-KOH; NaOH-LiOH; LiOH-KOH; and NaOH-KOH-LiOH.

[0103] In one embodiment, the molten salt is comprised of NaOH and KOH in a mol% ratio such as 30-70:30-70, such as 40-60:40-60, such as 45-55:45-55, such as 51:49.

[0104] In one embodiment, the molten salt comprises NaOH and LiOH in a mol% ratio such as 50-90:10-50, 65-75:25-35, or 70:30.

[0105] In one embodiment, the molten salt is comprised of KOH and LiOH in a mol% ratio such as 65-75:25-35, or 69:31.

[0106] In one embodiment, the molten salt comprises NaOH, KOH and LiOH in a mol% ratio such as 1-99:1-99:1-99, or 20-60:20-60:0-40. Preferably, the mol% of LiOH of such a mixture of salts is 20% or less, such as 15% or less, such as around 10%.Preferably, the solubilising salt is water-soluble. That is, preferably, the solubilising salt preferably dissociates on contact with water.

[0107] Metal hydroxides, and in particular alkali metal hydroxides, are examples of solubilising salts that are highly water-soluble.

[0108] Reductant

[0109] The first composition of the disclosure also comprises a reductant. The purpose of the reductant is to reduce the target metal such that it can be recovered.

[0110] In some embodiments, the presence of the reductant may also drive dissolution of the target metal in the molten salt. That is, the proportion or speed of dissolution may be increased, or the temperature required to obtain dissolution may be reduced by the presence of the reductant.

[0111] In addition, in some embodiments, the reductant may also adjust the redox potential of the molten salt of the first composition further increasing dissolution of the target metal in the first composition. That is, the proportion or speed of dissolution may be increased, or the temperature required to obtain dissolution may be reduced by adjusting the molten salt's redox potential.

[0112] Species in contact with the melt may undergo reduction or oxidation reactions depending on parameters including the redox potential of the melt, the acidity of the melt, and the melt temperature. If a species contacted with the melt causes a reduction in the oxidation state of the species, it is referred to as a reductant.

[0113] Preferably, the reductant causes reduction of the target metal in the process of the disclosure. The reduction of the target metal may be such that the target metal undergoes full reduction (e.g., all the way to its metallic (zero-valent state)) or partial reduction (e.g., the metal-containing species is reduced to a lower oxidation state but not to the zero-valent state).

[0114] Typically, the interaction between the reductant and the target metal occurs between the reductant and a metal ion. That is, typically, the reductant reduces the target metal after dissolution into the molten salt.For instance, dissolution of cobalt may provide a positive Co species in the molten salt. The positive Co ion may then be reduced by the reductant to form solid Co metal. Such a reaction can be difficult if both components are in solid form as the kinetics are slow and an incomplete reaction is likely to arise.

[0115] Examples of reducing agents include metals, particularly alkali metals and alkaline earth metals, hydrogen gas, metal hydrides, and carbon, such as graphite or coke.

[0116] In an embodiment, the reducing agent is a metal, such as aluminium. Preferably, the reductant comprises aluminium. In a particular embodiment, the aluminium may be provided in the form of aluminium sheets, powder or as fine particles.

[0117] Surprisingly, it has been found that providing a first composition comprising a reductant improves the recovery of target metals from the first composition due to effective reduction of the target metal e.g. to form a metallic metal precipitate.

[0118] Preferably, the reductant is a solid. Solid reductants are safer that gas-phase reductants and are therefore highly suitable for large-scale applications.

[0119] In particularly preferred embodiments, the reductant comprises a carbon allotrope such as such as hard carbon, graphene, graphite, carbon nanotubes, carbon nanofibers, carbon black, acetylene black, Ketjenblack, Super P, or combination thereof. Preferably the reductant comprises graphite.

[0120] In particularly preferred embodiments, the carbon allotropes are solid carbon allotropes. The term "solid carbon allotrope" refers to a form of elemental carbon that exists in solid phase at room temperature and atmospheric pressure. Solid carbon allotropes include, but are not limited to, hard carbon, graphite, graphene, carbon nanotubes, carbon nanofibers, carbon black, acetylene black, Ketjenblack, Super P and combinations thereof. In some embodiments, the solid carbon allotrope may be provided in particulate form, such as a powder or granules. For the avoidance of doubt, the solid carbon allotrope is distinguished from organic carbon sources that require cracking or decomposition at elevated temperatures to release carbon atoms, in that the solid carbon allotrope directly participates in reduction reactions with the target metal without requiring a cracking step to generate atomic or monoatomic carbon.The process of the disclosure advantageously employs a solid reductant, such as a carbon allotrope, that directly reduces the target metal without requiring a cracking step. This provides a simpler and more controllable process.

[0121] In a particularly preferred embodiment, the carbon allotrope is an inorganic carbon source.

[0122] Surprisingly, carbon allotropes are particularly robust reductants in the context of the disclosure and can reduce target metal in a wide range of conditions. For example, carbon allotropes such as graphite can reduce target metals in highly acidic, basic and neutral melt conditions.

[0123] Processes of recovering target metals using reductants are known. For example, carbothermic reduction of a target metal is a known process of target metal reduction.

[0124] Providing a first composition comprising a molten salt and a reductant provides advantages over such known processes.

[0125] Firstly, recovering a target metal via carbothermic reduction requires high temperatures which may volatilize the target metal. Such forms are difficult to recover, particularly at scale.

[0126] In addition, carbothermic reduction may result in the target metal being converted to a metal carbonate, or a mixtures of metal carbonates when multiple target metals are present. Metal carbonates are typically insoluble in water and therefore achieving selective recovery via direct production of a metal carbonate is associated with poor selectivity.

[0127] In contrast, the process of the disclosure comprising a molten salt typically results in the conversion of the target metal to a metal hydroxide (when the molten salt comprises a hydroxide solubilising salt) as a first step. Molten hydroxides are typically water-soluble which provides greater flexibility in terms of the potential recovery techniques that can be used in step (iii).

[0128] In an example, when the target metal of the first composition comprises lithium and cobalt, lithium hydroxide and cobalt hydroxide may be formed in step (i). Lithium hydroxide can be separated easily from the cobalt hydroxide by an adjustment step (for instance acidity). After separation, the lithium hydroxide may then be convertedto solid form of the target metal such as lithium carbonate in order to facilitate easy separation. Such a process provides a lithium carbonate product that is not contaminated with, for example cobalt carbonate, and is therefore a more selective process compared to carbothermic reduction for the recovery of target metals.

[0129] Preferably, the first composition comprises at least a stoichiometric ratio of reductant to target metal.

[0130] Preferably, the first composition comprises a mole ratio of at least 1:1-1:100 of target meta I: reductant, for instance from 1:1.2-1:80, from 1:1.4-1:60, from 1:1.6-1:40, from 1:2-1:30 or from 1:3-1:20 of target metal: reductant.

[0131] In the context of the disclosure, a stoichiometric ratio of target metal to reductant may refer to the ratio of reductant to all target metals in the first composition, or it may refer to the ratio of reductant to one or more of the target metals in the first composition.

[0132] In some embodiments, sufficient reductant is provided to reduce one of the target metals in the first composition.

[0133] In some embodiments, sufficient reductant is provided to completely reduce the target metal(s) in the first composition.

[0134] In the context of the disclosure, a stoichiometric ratio of reductant to target metal refers to the minimum amount of reductant required to fully reduce the target metal from its oxidised state to a desired reduced state. The stoichiometric ratio may vary depending on the oxidation state of the target metal in the first composition and the nature of the reductant. For example, when the reductant is a carbon allotrope such as graphite and the target metal is cobalt present as Co3+(such as in LiCoCh), the stoichiometric ratio for complete reduction to metallic cobalt may be calculated based on the transfer of three electrons per cobalt atom. Similarly, when the target metal is nickel present as Ni2+(such as in NMC materials), the stoichiometric ratio for complete reduction to metallic nickel may be calculated based on the transfer of two electrons per nickel atom. In some aspects, when the first composition comprises more than one target metal, the stoichiometric ratio may be calculated with respect to the total electron transfer required to reduce all target metals, or it may be calculated with respect to a single target metal that is intended to be selectively reduced. In some cases, providing a reductant in excess of the stoichiometric ratio may be preferred inorder to ensure complete reduction of the target metal or to account for competing reactions such as oxidation of the reductant by oxygen or water present in the system.

[0135] Preferably, the temperature of the first composition is set such that the reductant can reduce the target metal efficiently.

[0136] For instance, in some embodiments, a minimum temperature is required in order to affect the reducing behaviour of the reductant.

[0137] Preferably, the temperature of the first composition is at least 100°C, such as at least 170°C, at least 200°C, at least 250°C, at least 300°C, preferably at least 350°C, even more preferably at least 400°C.

[0138] Target metal

[0139] The first composition comprises a target metal. The purpose of the process as described herein is to recover the target metal.

[0140] In the context of the disclosure, a target metal is a metal that can be recovered using the process described herein. The target metal may be comprised in any suitable form within the first composition.

[0141] Typically, the target metal is a valuable metal, or a metal for which there is high demand.

[0142] Preferably the target metal is a transition metal, d-block metal, alkali metal, alkali earth metal, or combinations thereof.

[0143] Examples of target metals include cobalt, nickel, manganese, copper, iron, titanium, aluminium, zinc, chromium, molybdenum, vanadium, tin, lead, cadmium, silver, gold, platinum, lithium, sodium, calcium, potassium, magnesium, or combinations thereof.

[0144] Preferably, the first composition comprises more than one target metal, that is, the first composition comprises a mixture of target metals.

[0145] Preferably, the first composition comprises more than one target metal, for instance at least two selected from the list comprising nickel, cobalt, manganese, iron, and lithium.Even more preferably, the first composition comprises at least one transition metal and lithium.

[0146] Preferably, the first composition comprises manganese and at least one of cobalt and nickel.

[0147] In such embodiments, the first composition may be referred to as comprising a first and a second target metal.

[0148] The process of the disclosure is particularly advantageous for recovering a target metal from a mixture of target metals.

[0149] For instance, the process of the disclosure is particularly useful for separating manganese from a mixture of cobalt and nickel, and the process of the disclosure is particularly useful for separating lithium from transition metals.

[0150] Accordingly, the process of the disclosure provides improved selectivity over known methods, optionally in addition to providing a less energy consuming process.

[0151] Feedstock

[0152] In some embodiments, the target metal and the reductant are derived from a feedstock.

[0153] Preferably, the target metal is derived from a feedstock. In the context of the disclosure, the term "feedstock" may be used to refer to a composition comprising a target metal for recovery. The feedstock is preferably a waste material, for example a battery waste material or a magnetic waste material.

[0154] In some embodiments, the target metal is derived from a battery waste material or a magnetic waste material.

[0155] In the context of the disclosure "waste" material refers to any material which is no longer useful and is set to be recycled or discarded.

[0156] Preferably, the target metal is derived from industrial waste, for instance from battery waste or magnetic waste.Battery waste accounts for a large proportion of industrial waste comprising high-value target metals, much of which is in the form of lithium-ion battery (LIB) waste. Battery waste typically comprises all the high-value materials that were present when the batteries were manufactured.

[0157] During use, the performance of a battery degrades due to chemical and structural changes within the battery components. Recovering these materials and using them to produce new battery components is an important area of development, both for sustainability and security reasons.

[0158] Most commonly, the cathode is of most interest to battery recyclers as it contains the majority of the high value materials. There are multiple cathode materials used in LIBs, including, but not limited to Lithium Nickel Manganese Cobalt Oxide (NMC, LiNi-xMnyCozO? (where x+y+z=l)), Lithium Nickel Cobalt Aluminium Oxide (NCA, LiNixCoyAlzO? (where x+y+z=l)), Lithium Manganese Oxide (LMO, LiMn?O4), Lithium Iron Phosphate (LFP, LiFePO4), and Lithium Cobalt Oxide (LCO, UCOO2), Lithium-Manganese-Iron-Phosphate (LMFP, LiMnxFeyPO4 (where x+y=l)).

[0159] In some embodiments, the target metal of the first composition is derived from a cathode material. In the context of the disclosure, a "cathode material" refers to a composition comprising one or more target metals that is suitable for use as, or derived from, a cathode in an electrochemical cell. A cathode material may comprise a cathode active material, which refers to the electrochemically active component of the cathode that participates in charge storage and release. Accordingly, when the target metal is derived from a cathode material, the target metal may be derived from a cathode active material comprised within the cathode material.

[0160] In some embodiments the target metal of the first composition is derived from a lithium-ion battery material, such as lithium-ion cathode active material.

[0161] That is, in some embodiments target metal is derived from a feedstock wherein the feedstock comprises an electrode material, such as a cathode material.

[0162] In some embodiments the feedstock comprises one or more lithium-ion cathode materials based on oxides, optionally selected from the group comprising of:

[0163] Lithium Nickel Manganese Cobalt Oxide (NMC, LiNixMnyCozO2(where x+y+z=l)),Lithium Nickel Cobalt Aluminium Oxide (NCA, LiNiCoAIO?),

[0164] Lithium Manganese Oxide (LMO, LiMn?O4),

[0165] Lithium Iron Phosphate (LFP, LiFePO4),

[0166] Lithium Cobalt Oxide (LCO, LiCoCh),

[0167] Lithium-Manganese-Iron-Phosphate (LMFP, LiMnxFeyPO4 (where x+y=l)).

[0168] That is, preferably the first composition comprises Lithium Nickel Manganese Cobalt Oxide (NMC, LiNixMnyCozO?), Lithium Nickel Cobalt Aluminium Oxide (NCA, LiNixCoyAlzO? (where x+y+z=l)), Lithium Manganese Oxide (LMO, LiMn?O4), Lithium Iron Phosphate (LFP, LiFePO4), Lithium Cobalt Oxide (LCO, LiCoCh), Lithium-Manganese-Iron-Phosphate (LMFP, LiMnxFeyPO4(where x+y=l)) or combinations thereof.

[0169] Some cathode active materials, such as LFP or LMFP, and magnetic materials, such as AINiCo, are particularly difficult to break down using known processes and therefore recovery of target metals from such materials is challenging.

[0170] In some embodiments, the target metal is derived from a sodium-ion battery material. Sodium-ion batteries may comprise cathode materials based on layered oxides, polyanionic compounds, or Prussian blue analogues, preferably layered oxides or polyanionic compounds .

[0171] Sodium-ion battery cathode materials may comprise one or more target metals selected from nickel, manganese, iron, cobalt, copper, titanium, vanadium, or combinations thereof. In some embodiments, the feedstock may comprise sodium-ion battery waste material, such as sodium-ion battery black mass.

[0172] In some embodiments, the feedstock comprises sodium-ion battery black mass. Sodium-ion battery black mass may comprise layered oxides of nickel, manganese and iron, and may further comprise hard carbon as an anode material. In such embodiments, the hard carbon present in the sodium-ion battery black mass may serve as the reductant according to the disclosure. Accordingly, in some embodiments, both the target metal and the reductant may be derived from a common feedstock comprising sodium-ion battery waste material.

[0173] In some embodiments, the reductant comprises hard carbon. Hard carbon is a non-graphitisable form of carbon that is commonly used as an anode material in sodium-ion batteries. Hard carbon may function as a reductant in the process of the disclosurein a similar manner to graphite or other carbon allotropes. In some embodiments, hard carbon derived from sodium-ion battery waste may be used as the reductant for recovering target metals from the same waste material.

[0174] In some embodiments, the feedstock comprises one or more sodium-ion cathode materials selected from the group comprising layered sodium transition metal oxides (such as NaNixMnyFezO2 (where x+y+z=l)), sodium iron phosphate (NaFePC ), sodium vanadium phosphate (Na3V2(PC>4)3), sodium manganese oxide (NaMnCh), Prussian blue analogues, or combinations thereof. In a preferred embodiment, the feedstock comprises one or more sodium-ion cathode materials selected from the group comprising layered sodium transition metal oxides (such as NaNixMnyFezO2 (where x+y+z=l)), sodium iron phosphate (NaFePC ), sodium vanadium phosphate (Na3V2(PO4)3), sodium manganese oxide (NaMnCh), or combinations thereof.

[0175] The process of the disclosure is therefore applicable to both lithium-ion battery waste and sodium-ion battery waste, providing a versatile method for recovering target metals from a range of battery chemistries.

[0176] It is advantageous to provide a method wherein a battery waste and / or magnetic waste can be treated directly, and comprising minimal pre-treatment steps to separate out the various different components.

[0177] This can however be challenging as the composition of the waste will vary depending on the chemistry of the batteries and / or magnets from which is derived. For instance, examples of the variation in black mass composition are provided in Table 1, estimated from known amounts of materials in waste LIBs.

[0178]

[0179] Table 1.

[0180] The process of the disclosure which provides improved selectivity of mixed target metals, may be advantageously used to recover target metals from battery waste and / or magnetic waste.

[0181] Another complication of recycling battery waste and / or magnetic waste is the presence of other, non-metal components such as conductive materials. Conductive materials are often added to battery components in order to improve the electronic properties. Typically, the conductive material is a carbon material.

[0182] Advantageously, the conductive material may be a reductant according to the disclosure, for instance when the conductive material is a conductive carbon material.

[0183] In preferred embodiments, the feedstock from which the target metal is derived also comprises a reductant. That is, the target metal and the reductant may be derived from the same source.

[0184] In some embodiments, the feedstock comprises a conductive material, wherein the reductant comprises a carbon allotrope such as hard carbon, graphene, graphite, carbon nanotubes, carbon nanofibers, carbon black, acetylene black, Ketjenblack, Super P, or combination thereof.

[0185] In preferred embodiments, the feedstock comprises graphite.In some embodiments, the target metal is derived from a feedstock comprising battery waste material and / or magnetic waste material, optionally wherein the feedstock comprises one or more lithium-ion cathode materials selected from Lithium Nickel Manganese Cobalt Oxide (NMC), Lithium Nickel Cobalt Aluminium Oxide (NCA), Lithium Manganese Oxide (LMO), Lithium Iron Phosphate (LFP), Lithium Cobalt Oxide (LCO), Lithium-Manganese-Iron-Phosphate (LMFP), AINiCo, or combinations thereof.

[0186] In some embodiments, the feedstock comprises one or more selected from the list of AINiCo.

[0187] Processing the molten salt

[0188] Step (ii) comprises processing the first composition to form a solid comprising the target metal.

[0189] The solid may comprise the target metal in any suitable form. For example, the solid composition may comprise the target metal as a metal hydroxide, metal carbonate, metal phosphate, metal oxide, metal oxyhydroxide, a metal, or combinations thereof.

[0190] Preferably, forming a solid comprising the target metal is not achieved by electrodissolution directly from the first composition. Electrodissolution requires applying an electric potential directly to the molten salt which increases process complexity and may cause counter-reactions in the first composition that affect the balance of the system.

[0191] Preferably, step (ii) is carried out for a time sufficient to produce a form of the target metal suitable for recovery. This may include both dissolution of the target metal and formation of the solid comprising the target metal.

[0192] The exact time required may depend on the temperature. For instance, if the process is carried out using a high temperature first composition, the duration of step (ii) may be shorter. Conversely, if the process is carried out using a low temperature first composition, the duration of step (ii) may be longer.

[0193] Preferably, step (ii) is carried out for at least 1 hour.In some embodiments, step (ii) is carried out for a duration of from 1 to 20 hours, for instance from 2 to 19 hours, from 2 to 18 hours, from 4 to 17 hours, from 6 to 16 hours, from 7 to 15 hours, from 8 to 14 hours, from 9 to 13 hours or for around 12 hours.

[0194] In some embodiments, "processing the first composition" comprises cooling the first composition below its melting point in order for it to solidify. Solidification of the first composition may be achieved by any suitable method. For instance, the solid composition may be obtained by actively or passively cooling the first composition.

[0195] In such embodiments, the composition of the solid composition may be the same as the composition of the molten salt. Accordingly, in such embodiments, "processing" refers simply to changing the state of matter of the molten salt from liquid to solid.

[0196] In some embodiments, "processing the first composition" comprises forming an enriched solid.

[0197] As used herein, the term "enriched solid" refers to a solid composition that contains a higher concentration of a target metal relative to another composition from which it was derived or separated. The enriched solid may comprise the target metal in any suitable form, for example as a metal hydroxide, metal carbonate, metal phosphate, metal oxide, metal oxyhydroxide, or as a metallic metal.

[0198] In some aspects, the enriched solid may be formed by precipitation from a molten salt, and in such cases the enriched solid contains the target metal in enriched form compared to the residual molten salt from which it was separated.

[0199] In a preferred embodiment, the process of the disclosure increases the metal mole percentage of the target metal in the solid comprising the target metal relative to the metal mole percentage of the target metal in the feedstock. That is, the metal mole percentage of the target metal is higher in the solid comprising the target metal than in the feedstock from which the target metal was derived.

[0200] By "metal mole percentage" is meant the mole percentage of a metal in a composition expressed as a percentage relative to all of the metals in the composition. An alloy with 50 mol% nickel and 50 mol% cobalt would have 50 metal mole percent nickel and 50 metal mole percent cobalt. Likewise, the corresponding oxide Ni0.5Co0.5O2 also has 50 metal mole percent nickel and 50 metal mole percent cobalt, even though theabsolute mole percent of nickel and cobalt in the oxide is lower when taking account of the oxygen that is also present.

[0201] For example, when the feedstock is a battery waste material comprising a mixture of target metals such as lithium, nickel, cobalt, and manganese, the process may produce an enriched solid in which the metal mole percentage of one or more of these target metals is increased in the enriched solid compared to the feedstock.

[0202] In some embodiments, the enriched solid may comprise a metal mole percentage of the target metal that is at least 1.5 times, at least 2 times, at least 3 times, at least 5 times, or at least 10 times higher than the metal mole percentage of the target metal in the feedstock.

[0203] In some embodiments, the process may selectively enrich one target metal relative to another target metal. For example, when the feedstock comprises nickel, cobalt, and manganese, the process may produce an enriched solid in which the mole percentage of nickel and cobalt is increased while the mole percentage of manganese is decreased, relative to the total metal content. In some aspects, the process may produce an enriched solid that is substantially free of one or more metals that were present in the feedstock. As used herein, "substantially free" means that the metal is present at less than 5 mol%, less than 2 mol%, less than 1 mol%, or less than 0.5 mol% of the total metal content in the enriched solid.

[0204] Accordingly, the process of the present disclosure comprises the steps of:

[0205] i. Providing a first composition as a molten salt, said molten salt comprising a solubilising salt, a reductant and a target metal; and

[0206] ii. Processing the first composition to form an enriched solid comprising the target metal, wherein the enriched solid has a higher metal mole percentage of the target metal than the metal mole percentage of the target metal in a feedstock from which the target metal was derived; and

[0207] iii. Recovering the enriched solid.

[0208] Such processes may be viewed as a process for enriching the metal mole percentage of a target metal in a feedstock.

[0209] In some embodiments, the enriched solid may comprise the target metal in the form of an alloy. For example, when the first composition comprises more than one target metal, such as nickel and cobalt, the enriched solid may comprise a nickel-cobalt alloy.In some embodiments, the alloy may further comprise copper, iron, or other metals present in the first composition. The alloy may be magnetic, which may facilitate recovery of the enriched solid from the first composition or from an aqueous composition by magnetic separation. In some embodiments, the enriched solid may comprise a mixture of metallic target metals and alloys of target metals.

[0210] In some embodiments, the target metal is a maximum of 99 metal mol.% of the enriched solid. For instance, the target metal is a maximum of 98 metal mol.%, such as 95 metal mol.%, 90 metal mol.% or 85 metal mol.% of the enriched solid.

[0211] In some embodiments, when the target metal is derived from a feedstock comprising a polymetallic compound or alloy, the process may produce an enriched solid in which the target metals are present as a different alloy composition than the feedstock. For example, when the feedstock is an AINiCo magnet comprising aluminium, nickel, cobalt, copper, and iron, the process may produce an enriched solid comprising a nickel-cobalt-copper alloy that is substantially free of aluminium. In such embodiments, the metal mole percentage of nickel, cobalt, and copper in the enriched solid may be higher than the metal mole percentage of these metals in the feedstock.

[0212] Any suitable method of forming an enriched solid may be used.

[0213] For example, the first composition may be adjusted in order to form an enriched solid, wherein the enriched solid is in the form of a precipitate comprising the target metal.

[0214] An embodiment of the disclosure therefore relates to a process wherein step (ii) comprises processing the first composition to provide an enriched solid and a residual composition (said residual composition being a molten salt), wherein the enriched solid contains the target metal in enriched form compared to the residual composition.

[0215] As used herein, the term "residual composition" refers to the composition that remains after a target metal has been at least partially removed or separated therefrom. The residual composition may be a molten salt that has been depleted of one or more target metals, or it may be an aqueous composition from which a target metal has been recovered. In some aspects, the residual composition may itself comprise one or more target metals that differ from the target metal that was removed, and such remaining target metals may be subsequently recovered in further processing steps.In some embodiments, processing the molten salt in step (ii) comprises adjusting the first composition to provide an enriched solid.

[0216] In some embodiments, processing the molten salt in step (ii) comprises adjusting the first composition in order to increase the yield of enriched solid.

[0217] For example, the acidity, redox potential, temperature, chemical composition and / or pressure of the first composition may be adjusted.

[0218] Accordingly, step (ii) may comprise the steps(s) of;

[0219] - adjusting the acidity / basicity of the first composition;

[0220] - adjusting the redox potential of the first composition;

[0221] - adjusting the temperature of the first composition;

[0222] adjusting the chemical composition of the first composition;

[0223] - adjusting the pressure of the first composition; and

[0224] any combination thereof.

[0225] For instance, step (ii) may comprise processing the molten salt by adjusting the first composition in order to precipitate a target metal.

[0226] The enriched solid may comprise the target metal in any suitable form, for example the enriched solid may comprise a target metal as a metal hydroxide, metal carbonate, metal phosphate, metal oxide, a metal oxyhydroxide, or a metal.

[0227] In preferred embodiments, the enriched solid comprises a metallic target metal.

[0228] In preferred embodiments, the enriched solid consists of a metallic target metal.

[0229] In preferred embodiments the residual composition contains no target metal. That is, in preferred embodiments, the total precipitation of the target metal is achieved by processing the molten salt.

[0230] In some embodiments, "processing the first composition" comprises:

[0231] processing the first composition to provide an enriched solid and a residual composition (said residual composition being a molten salt), wherein the enriched solid contains the target metal in enriched form compared to the residual composition; andcooling the residual composition (molten salt) to form a solid residual composition, optionally wherein

[0232] - the solid residual composition comprises a target metal.

[0233] In such embodiments, preferably the solid residual composition comprises a target metal.

[0234] Even more preferably, the target metal of the solid residual composition is different from the target metal of the enriched solid.

[0235] Step (ii) may comprise processing of the first composition in more than one way.

[0236] For instance, step (ii) may comprise:

[0237] processing a first part of the first composition to provide an enriched solid and a residual composition (said residual composition being a molten salt), wherein the enriched solid contains the target metal in enriched form compared to the residual composition; and

[0238] cooling a second part of the first composition to form a solid comprising the target metal.

[0239] Step (ii) may comprise processing of the whole first composition, or it may comprise processing the at least part of the first composition.

[0240] Recovering the target metal

[0241] The process of the disclosure comprises recovering a target metal.

[0242] In the context of the disclosure, "recovering a target metal" refers to any step in which a target metal in the first composition is separated or isolated from at least one other component of the first composition.

[0243] Preferably, "recovery of a target metal" refers to a step in which a target metal in the first composition is separated from another target metal also comprised in the first composition.

[0244] The target metal may be recovered in any suitable form. Typically, the target metal is recovered in the form of a metal hydroxide, metal carbonate, metal phosphate, metal oxide, a metal oxyhydroxide, a metal, or combinations thereof.In some embodiments, the target metal in the first composition is the same metal species as the target metal recovered. In other embodiments, the target metal is transformed from one species to another in the process of the disclosure in order to facilitate easier recovery.

[0245] Preferably, the process of the disclosure comprises recovering 10wt% or more of the target metal, for instance 20wt% or more, 30wt% or more, 40wt% or more, 50wt% or more, or 60wt% or more, 70wt% or more, 80wt% or more, 90wt% or more or 95 wt% or more.

[0246] The process of the disclosure may comprise repeating the step of recovering a target metal in order to increase the yield of recovery.

[0247] The process of the disclosure may comprise repeating the step of recovering a target metal in order to provide an efficient, semi-continuous process. In such embodiments, the first composition may be replenished of target metal in order to provide more target metal for recovery.

[0248] The multiple recovery steps may be carried out using the same processing conditions and / or processing parameters, or different conditio ns / para meters may be used for each of the recovery steps.

[0249] Preferably, in embodiments comprising multiple recovery steps, the target metal is recovered, and the components of the composition from which it is recovered are reused in the second recovery step. For instance, preferably recovery of the target metal results in retention of the solubilising salt that can be re-used to form more first composition.

[0250] The re-used components may require processing in order to provide more first composition. For example, additional heating, stirring, agitating, mixing and / or chemical adjustment may be required.

[0251] Step (iii) may comprise partial or total recovery of a target metal from the first composition.

[0252] Preferably, step (iii) comprises recovery of 10 mol% or more of the metal species from the first composition, for instance recovery of 15 mol% or more, 20 mol% or more, 30mol% or more, 40 mol% or more or 50 mol% or more of the metal species from the first composition.

[0253] Even more preferably, step (iii) comprises recovery of 20 mol% or more of the target metal from the first composition, for instance recovery of 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more or 70 mol% or more of the target metal from the first composition.

[0254] The skilled person understands that the recovery of the target metal in step (iii) may be carried out using standard techniques known in the art. In some embodiments, the enriched solid comprising the target metal may be subjected to a downstream hydrometallurgical process to further purify or separate the target metal. Downstream hydrometallurgical processes include, but are not limited to, ammoniacal leaching, acidic sulphate oxidative leaching, chloride leaching, and pressure oxidative leaching. In some embodiments, the target metal may be recovered from an aqueous composition using one or more techniques selected from cementation, steam stripping, solvent extraction, ion exchange, and electrowinning.

[0255] In some embodiments, the enriched solid produced by the process of the disclosure may be provided as a feedstock for downstream hydrometallurgical processing. Advantageously, the enriched solid may have a higher concentration of target metal than the original feedstock, which may improve the efficiency of downstream recovery processes. In some embodiments, the enriched solid may be substantially free of certain impurities, such as carbon, plastics, or binders, that were present in the original feedstock, which may simplify downstream processing.

[0256] In some embodiments, the process of the disclosure may be combined with one or more downstream recovery techniques to provide a complete process for recovering purified target metal from a feedstock such as battery waste material or magnetic waste material.

[0257] In some embodiments, step (iii) comprises recovering the target metal via a physical separation technique, for instance filtration.

[0258] For example, precipitated species formed in step (ii) can be separated from the residual composition by filtering processed composition (comprising precipitate and molten salt).Physical separation techniques are particularly preferred when the solid composition is an enriched solid according to the disclosure.

[0259] In some embodiments the enriched solid is magnetic. In such embodiments, the enriched solid may be recovered from the first composition magnetically, such as by using a magnetic rod.

[0260] In order to recover the target metal from the solid composition, step (iii) may comprise contacting the solid comprising target metal with an aqueous solution.

[0261] Preferably, said solid composition comprises both target metal and a solubilising salt. The first composition comprises solubilising salt, therefore its contact with an aqueous solution causes the formation of an aqueous composition comprising the target metal.

[0262] An embodiment of the disclosure therefore relates to a process wherein step (iii) comprises:

[0263] a. contacting the solid comprising the target metal with an aqueous solution to form an aqueous composition and recovering the target metal from the aqueous composition.

[0264] The solid comprising target metal of step (a) may or may not be an enriched solid. The target metal may be present in soluble or insoluble form in the aqueous composition.

[0265] Preferably, the aqueous composition comprises from 10 wt% or more water, such as from 20wt% or more, 30wt% or more, 40wt% or more, 50wt% or more, 60wt% or more or 70 wt% or more water.

[0266] When the target metal is present in insoluble form, step (a) may comprise recovery of the target metal via a physical separation step such as filtration.

[0267] When the target metal is present in soluble form, step (a) may alternatively or additionally comprise adjusting the aqueous solution comprising the target metal in order to provide the target metal in insoluble form.

[0268] For instance, the aqueous solution comprising the target metal may be adjusted in order to induce precipitation of the target metal.A physical separation step may then be used to recover the precipitate from the aqueous solution.

[0269] Preferably the target metal is precipitated as a metal hydroxide. Even more preferably, the target metal is precipitated as metal hydroxide when the target metal is a transition metal.

[0270] In some embodiments, step (a) comprises the steps(s) of;

[0271] - adjusting the acidity / basicity of the aqueous composition comprising the target metal;

[0272] - adjusting the redox potential of the aqueous composition comprising the target metal);

[0273] - adjusting the temperature of the aqueous composition comprising the target metal;

[0274] adjusting the chemical composition of the composition solution comprising the target metal;

[0275] - adjusting the pressure of the aqueous composition comprising the target metal;

[0276] and

[0277] any combination thereof.

[0278] For instance, step (a) may comprise adjusting the pH of the aqueous composition comprising target metal in order to precipitate the target metal i.e. to form an insoluble metal species from a soluble metal species.

[0279] Alternatively or additionally, step (a) may comprise adding a reagent to the aqueous composition comprising the target metal in order to precipitate the target metal. For instance, a carbonate-forming species may be added to the aqueous composition comprising the target metal in order to precipitate the target metal, wherein the precipitated target metal is a metal carbonate.

[0280] In one embodiment, the carbonate-forming species is a metal carbonate, such as Na?CO3 or K2CO3.

[0281] In one embodiment, the carbonate-forming species is CO2 gas.

[0282] In one embodiment, CO2 gas may be sparged or bubbled into the aqueous composition.Precipitation using a carbonate-forming species is particularly beneficial for recovering lithium as lithium carbonate.

[0283] Multiple precipitation steps may be used to selectively recover target metals from a first composition comprising a mixture of target metals.

[0284] For instance, in embodiments wherein the first composition comprises lithium and at least one transition metal, step (a) may comprise:

[0285] (x) Recovering a transition metal from the aqueous composition in the form of a transition metal hydroxide to form a residual aqueous composition;

[0286] Optionally wherein the transition metal hydroxide is formed by adjusting the pH of the aqueous composition;

[0287] (y) Adding a carbonate-forming species to the residual aqueous composition to form a lithium carbonate precipitate; and

[0288] (z) Recovering the lithium carbonate precipitate from the aqueous composition; wherein

[0289] a residual aqueous composition is the aqueous composition depleted of the transition metal recovered in step (x).

[0290] Target metals may also be present in the aqueous composition in the form of an unstable metal species. In the context of the disclosure, an "unstable" species refers to a species that, when in aqueous solution, will react to form other species. The driving force for said reactions is thermodynamic, and the rate is determined by kinetic factors such as temperature and concentration.

[0291] The presence of the target metal in the aqueous composition as a combination of soluble, insoluble and / or unstable metal species may advantageously allow for selective recovery of target metals.

[0292] Selective recovery processes are particularly useful for recovering metal species from a first composition comprising more than one target metals.

[0293] For example, this may allow for selective separation of one or more transition metals from a combination of transition metals. For instance, selective separation may be used to recover manganese from a mixture of cobalt, nickel and manganese, as is often found in battery waste.Advantageously, a combination of different recovery steps may also be used in order to provide selective recovery.

[0294] In some embodiments, the process of the disclosure comprises the additional step of recovering a target metal directly from the molten salt before processing the molten salt in step (ii). Such embodiments are particularly preferred when the first composition comprises more than one target metal. That is, a first and a second target metal.

[0295] For example, a target metal may be recovered directly from the molten salt using electrodeposition. This is particularly suitable where the target metal is present in the first composition in soluble form.

[0296] Here, for example, an electrochemical system comprising at least two electrodes can be used to apply a potential difference to the melt and plate species from the melt onto one of the electrodes. By controlling the potential difference between the two electrodes, species can be selectively deposited from the first composition. The electrode where the material has deposited can then be separated from the molten salt to recover the species.

[0297] Some target metals are difficult or impossible to recover directly from a molten salt. For instance, it is challenging to recover lithium or manganese directly from a molten salt by electrodeposition. This is because the reduction potential of lithium and manganese is below that of other alkali metals and reduction of water to hydrogen. As such, the entire solvent would have to be reduced to recover lithium or manganese by this means, leading to a low efficiency, high consumption and high-cost process.

[0298] Other target metals, such as cobalt or nickel for example, are far easier to recover directly from the molten salt by electrodeposition, however.

[0299] Accordingly, when the first composition comprises a mixture of target metals, for instance when the first composition comprises lithium and at least one transition metal, performing an electrodeposition step following processing the molten salt can be used to selectively separate the mixture of target metals.

[0300] In an embodiment, the process of the disclosure comprises:

[0301] i. Providing a first composition as a molten salt, said molten salt comprising a solubilising salt, a reductant, a first target metal and a second target metal;1. Recovering the first target metal from the molten salt by electrodeposition to form a depleted molten salt;

[0302] ii. Processing the depleted molten salt to form a solid comprising the second target metal; and

[0303] iii. Recovering the second target metal,

[0304] a. Wherein preferably recovering the second target metal comprises contacting the solid comprising the target metal with an aqueous solution to form an aqueous composition, and recovering the target metal from the aqueous composition.

[0305] As used herein, the term "depleted molten salt" refers to a molten salt from which at least a portion of one or more target metals has been removed. The depleted molten salt may be formed, for example, by electrodeposition of a target metal from the molten salt, or by precipitation and physical separation of an enriched solid comprising the target metal. In some aspects, the depleted molten salt may retain one or more other target metals that were not removed, and such retained target metals may be recovered in subsequent processing steps.

[0306] Such embodiments may be used to selectively recover a target metal when the first composition comprises a battery waste material.

[0307] For example, in the processing of an NMC cathode material, nickel and cobalt metal species can be easily recovered from the first composition by electrodeposition, to form a depleted molten salt comprising manganese. Recovering manganese from the depleted molten salt is difficult and therefore it is preferable to process the depleted molten salt to form a solid composition comprising manganese. The solid composition comprising manganese, but now depleted of nickel and cobalt, may be processed and contacted with an aqueous composition in step (iii). Manganese is water-soluble and thus step (iii) would provide manganese in solution.

[0308] The manganese may then be recovered from solid composition via any suitable method, for instance via an aqueous pH precipitation step, or in some instances, the manganese may spontaneously precipitate.

[0309] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.All embodiments of the invention and particular features mentioned herein may be taken in isolation or in combination with any other embodiments and / or particular features mentioned herein (hence describing more particular embodiments and particular features as disclosed herein) without departing from the disclosure of the invention.

[0310] As used herein, the term 'comprises' will take its usual meaning in the art, namely indicating that the component includes but is not limited to the relevant features (i.e. including, among other things). As such, the term 'comprises' will include references to the component consisting essentially of the relevant substance(s).

[0311] Wherever the word 'about' is employed herein in the context of amounts, for example absolute amounts, weights, volumes, sizes, diameters etc., or relative amounts (e.g. percentages) of individual constituents in a composition or a component of a composition (including concentrations and ratios), timeframes, and parameters such as temperatures etc., it will be appreciated that such variables are approximate and as such may vary by ±10%, for example ±5% and preferably ±2% (e.g. ±1%) from the actual numbers specified herein. This is the case even if such numbers are presented as percentages in the first place (for example 'about 10%' may mean ±10% about the number 10, which is anything between 9% and 11%).'ITEMS

[0312] 1. A process for recovering a target metal comprising the steps of:

[0313] i. Providing a first composition as a molten salt, said molten salt comprising a solubilising salt, a reductant and a target metal; and

[0314] ii. Processing the first composition to form a solid comprising the target metal;

[0315] and

[0316] iii. Recovering the target metal.

[0317] 2. The process of item 1, wherein the first composition comprises a wt% molten salt of 20 wt% or more, such as from 30 wt% or more, 40wt% or more, 50wt% or more or 60wt% or more.

[0318] 3. The process of items 1-2 wherein the first composition comprises a weight ratio of 1:1 to 100:1 of molten salt:target metal for instance from 2:1 to 100:1, 3:1 to 75:1, from 5: 1 to 50:1, from 10:1 to 40:1 or from 15:1 to 30:1 of molten salt:target metal.

[0319] 4. The process of items 1-3 wherein the first composition has a temperature is in the range from 100°C to 1300°C, from 170°C to 1300°C, from 200°C to 1000°C, from 250°C to 800°C, from 300°C to 750°C, from 350°C to 700°C from 400°C to 650°C, from 100°C to 650°C, from 170°C to 650°C, from 200°C to 650°C or from 400 to 650°C .

[0320] 5. The process of item 1-4 wherein the solubilising salt is a metal hydroxide.

[0321] 6. The process of item 1-5, wherein the metal hydroxide is a hydroxide of an alkali metal or an alkaline earth metal, for instance lithium, sodium, potassium, caesium, rubidium, calcium or magnesium hydroxide, or mixtures thereof.

[0322] 7. The process of item 6 wherein the metal hydroxide is selected from LiOH, NaOH, KOH, CsOH, RbOH, NaOH-KOH, LiOH-KOH, LiOH-NaOH-KOH, and combinations thereof, preferably wherein the solubilising salt is KOH.

[0323] 8. The process of items 1-7, wherein the first composition comprises more than one solubilising salt species.9. The process of item 8, wherein the first composition comprises at least one alkali metal hydroxide, preferably wherein the first composition comprises at least two alkali metal hydroxides.

[0324] 10. The process of item 8 or 9 wherein the first composition comprises a metal hydroxide and a metal carbonate.

[0325] 11. The process of items 8-10, wherein the first composition comprises two solubilising salts in a mol% ratio such as 30-70:30-70, for instance 40-60:40-60, 45-55:45-55 or 51:49, preferably wherein the solubilising salts are NaOH and KOH respectively.

[0326] 12. The process of items 8-11 wherein the first composition comprises two solubilising salts in a mol% ratio such as 50-90: 10-50, for instance 65-75:25-35, or 70:30, preferably wherein the solubilising salts are NaOH and LiOH respectively.

[0327] 13. The process of items 8-12 wherein the first composition comprises two solubilising salts in a mol% ratio such as 65-75:25-35, for instance 69:31, preferably wherein the solubilising salts are KOH and LiOH respectively.

[0328] 14. The process of items 8-13 wherein the first composition comprises three solubilising salts in a mol% ratio such as 1-99:1-99:1-99 mol%, or for instance 20-60:20-60:0-40, preferably wherein the solubilising salts are NaOH, KOH and LiOH respectively.

[0329] 15. The process of items 1-14, wherein the reductant comprises a metal, alkali metal, alkaline earth metal, metal hydrides, carbon allotrope, or mixtures thereof.

[0330] 16. The process of items 1-15, wherein the reductant comprises a carbon allotrope such as hard carbon, graphene, graphite, carbon nanotubes, carbon nanofibers, carbon black, acetylene black, Ketjenblack, Super P, or combination thereof, preferably wherein the reductant comprises graphite.

[0331] 17. The process of items 1-16, wherein the reductant is a carbon allotrope, preferably a solid carbon allotrope.

[0332] 18. The process of items 1-17, wherein the reductant is a carbon allotrope from an inorganic carbon source.19. The process of items 1-18, wherein the target metal is a transition metal, d-block metal, alkali metal, alkali earth metal, and / or combinations thereof.

[0333] 20. The process of items 1-19, wherein the target metal is selected from the list comprising cobalt, nickel, manganese, copper, iron, titanium, aluminium, zinc, chromium, molybdenum, vanadium, tin, lead, cadmium, silver, gold, platinum, lithium, sodium, calcium, potassium, magnesium, or combinations thereof.

[0334] 21. The process of items 1-20, wherein the target metal is derived from a feedstock comprising a cathode material.

[0335] 22. The process of items 1-20, wherein the target metal is a magnetic material.

[0336] 23. The process of items 1-22 wherein the first composition comprises more than one target metal, for instance, the first composition comprises a first and a second target metal.

[0337] 24. The process of items 1-23 wherein the first composition comprises a mole ratio of at least 1: 1-1: 100 of target metal: reductant, for instance from 1: 1.2-1:80, from 1:1.4-1:60, from 1:1.6-1:40, from 1:2-1:30 or from 1:3-1:20 of target metal: reductant.

[0338] 25. The process of items 1-24 wherein the reductant and the target metal are derived from a feedstock, optionally wherein the feedstock comprises battery waste material and / or a magnetic waste material.

[0339] 26. The process of items 1-25 wherein processing the first composition comprising cooling the first composition to below the melting point of the molten salt.

[0340] 27. The process of items 1-26 wherein the solid comprising the target metal is an enriched solid having a higher metal mole percentage of the target metal than the metal mole percentage of the target metal in a feedstock from which the target metal was derived.

[0341] 28. The process of item 27, wherein the enriched solid comprises a metal mole percentage of the target metal that is at least 1.5 times, at least 2 times, at least 3 times, at least 5 times, or at least 10 times higher than the metal mole percentage of the target metal in the feedstock, calculated with respect to the total amount of metal in each composition.29. The process of items 1-28 wherein step (ii) comprises:

[0342] processing the molten salt to provide an enriched solid and a residual composition (said residual composition being a molten salt), wherein the enriched solid contains the target metal in enriched form compared to the residual composition.

[0343] 30. The process of item 29 wherein processing the molten salt comprises adjusting the first composition to provide an enriched solid.

[0344] 31. The process of items 1-30 wherein step (ii) comprises:

[0345] processing the first composition to provide an enriched solid and a residual composition (said residual composition being a molten salt), wherein the enriched solid contains the target metal in enriched form compared to the residual composition; and

[0346] cooling the residual composition (molten salt) to form a solid residual composition, optionally wherein

[0347] - the solid residual composition comprises a target metal.

[0348] 32. The process of items 1-31 wherein step (ii) comprises:

[0349] processing a first part of the first composition to provide an enriched solid and a residual composition (said residual composition being a molten salt), wherein the enriched solid contains the target metal in enriched form compared to the residual composition; and

[0350] cooling a second part of the first composition to form a solid comprising the target metal.

[0351] 33. The process of items 1-32 wherein step (iii) comprises;

[0352] a. contacting the solid comprising the target metal with an aqueous solution to form an aqueous composition comprising the target metal, and recovering the target metal from the aqueous composition.

[0353] 34. The process of item 33, wherein the aqueous composition comprises from 10 wt% or more water, such as from 20wt% or more, 30wt% or more, 40wt% or more, 50wt% or more, 60wt% or more or 70 wt% or more water.35. The process of item 1-34 wherein the first composition comprises a first and a second target metal.

[0354] 36. The process of item 35 wherein the first target metal is a transition metal, and the second target metal is lithium, and step (iii) comprises:

[0355] (x) Recovering a transition metal from the aqueous composition in the form of a transition metal hydroxide to form a residual aqueous composition;

[0356] Optionally wherein the transition metal hydroxide is formed by adjusting the pH of the aqueous composition;

[0357] (y) Adding a carbonate-forming species to the residual aqueous composition to form a lithium carbonate precipitate; and

[0358] (z) Recovering the lithium carbonate precipitate from the aqueous composition; wherein

[0359] a residual aqueous composition is the aqueous composition depleted of the transition metal recovered in step (x).

[0360] 37. The process of item 35 comprising:

[0361] i. Providing a first composition as a molten salt, said molten salt comprising a solubilising salt, a reductant, a first target metal and a second target metal;

[0362] 1. Recovering the first target metal from the molten salt by electrodeposition to form a depleted molten salt;

[0363] ii. Processing the depleted molten salt to form a solid comprising the second target metal; and

[0364] iii. Recovering the second target metal,

[0365] a. Wherein preferably recovering the second target metal comprises contacting the solid comprising the target metal with an aqueous solution to form an aqueous composition and recovering the target metal from the aqueous composition.

[0366] 38. The process of item 37 wherein:

[0367] - the first target metal is at least one of cobalt and nickel; and

[0368] - the second target metal is manganese.

[0369] 39. In step (ii) is carried out for a time sufficient to produce a form of the target metal suitable for recovery.40. The process of items 39 wherein "time sufficient to produce a form of the target metal suitable for recovery" include dissolution of the target metal and formation of the solid comprising the target metal.

[0370] 41. The process of items 1-40 wherein step (ii) is carried out for a duration of from 1 to 20 hours, for instance from 2 to 19 hours, from 2 to 18 hours, from 4 to 17 hours, from 6 to 16 hours, from 7 to 15 hours, from 8 to 14 hours, from 9 to 13 hours or for around 12 hours.Examples

[0371] Example 1

[0372] Target metal recovery from a range of cathode active materials was carried out using the process of the disclosure, with conditions according to Table 2.

[0373] In each case, the molten salt of the first composition was used as a solvent according to the disclosure.

[0374] The samples were prepared in alumina containers and therefore aluminium detected in the samples is likely to derive from the containers.

[0375]

[0376] Table 2.

[0377] Observations

[0378] Sample 1

[0379] Upon cooling of the first composition of sample 1, a white salt with metallic flakes visible on the surface was obtained. The salt being white is indicative of no dissolved transition metals. This solidified salt was dissolved in water with stirring to produce a loaded aqueous solution.

[0380] The solution was filtered, giving an alkaline filtrate with a blue colour and a magnetic solid.

[0381] The magnetic material indicates the presence of Co metal, and the blue colour in the filtrate indicates the presence of dissolved Co, likely [Co(OH)4]2-. Over time, the blue colour disappeared and the filtrate turned a green / brown colour, which is indicative of Co3+species (Co(II) - Co(III)).Elemental analysis detected the presence of lithium, aluminium and cobalt in the filtrate.

[0382] Sample 2

[0383] The first composition was blue in colour and comprised a metallic species.

[0384] Based on the thermodynamic data, it is unexpected that Mn is fully reduced to a metal because H2O in the molten hydroxide would be reduced to hydrogen first. Accordingly, the results indicate that Ni and Co have been removed from the molten hydroxide, leaving behind Mn dissolved in the salt.

[0385] Upon cooling and dissolving in water, a green filtrate and a metallic precipitate was obtained. The metallic precipitate was magnetic, indicating the presence of Co and / or Ni.

[0386] Upon standing, a brown precipitate formed in the filtrate, while the solution became colourless. This behaviour is a result of the soluble manganate ion (MnC2) converting to insoluble MnCh.

[0387] Elemental analysis detected the presence of lithium and aluminium in the filtrate. Sample 3

[0388] Upon cooling the first composition of sample 3, a non-homogeneous mixture of materials was obtained: a white and yellow salt was present, as well as a red / orange solid, and a metallic species.

[0389] The white material indicates the presence of NaOH, LiOH and alkali metal phosphate species; the yellow salt is likely due to the presence of salt soluble Fe species; the red material is Fe oxide; the metal species present is Fe metal.

[0390] The presence of Fe metal and absence of the typically black colour of graphite indicates that the graphite acted as a reductant in the process.

[0391] Elemental analysis detected the presence of lithium, phosphorus and aluminium in the filtrate.Sample 4

[0392] The first composition of sample 4 comprised 10wt% water, which results in an acidic melt.

[0393] Upon cooling the first composition of sample 4, the salt was cooled to room temperature, with a black material on the surface and a white bulk salt throughout. The solidified composition was dissolved in water and filtered which gave a clear, blue filtrate and a solid that was a mixture of black and grey material.

[0394] The blue filtrate corresponds to the soluble tetra hydroxocobaltate ion. There was no evidence of magnetic material related to metallic Co or Ni on the stirrer bar.

[0395] This experiment did not show the characteristic blue salt seen for Mn containing cathodes, suggesting that the Mn speciation here is different. This is due to the melt being acidic, not basic. Mn is likely present as an oxide such as MnO.

[0396] Upon standing, the blue filtrate lost its colour, consistent with oxidation of Co(II) to Co(III). The presence of tetra hydroxocobaltate, containing Co(II), followed by subsequent oxidation to Co(III) indicates that Co from NMC was reduced from +3 to +2 (or potentially to a metallic Co) during heating in the molten salt in the presence of graphite, despite the acidic conditions of the first composition.

[0397] Sample 5

[0398] Upon cooling the first composition of sample 5, a white salt solid with black material on the surface was obtained.

[0399] The solidified composition was dissolved in water and filtered which gave a clear, blue filtrate and a solid that appeared a mixture of black and grey material.

[0400] The blue filtrate corresponds to the soluble tetra hydroxocobaltate ion. There was no evidence of magnetic material related to metallic Co or Ni on the stirrer bar.

[0401] There was no observation of the characteristic blue salt seen for Mn containing cathodes, suggesting that the Mn speciation here is different. This is due to the melt being acidic, not basic. Mn is likely present as an oxide such as MnO.

[0402] Upon standing, the blue filtrate lost its colour, consistent with oxidation of Co(II) to Co(III). The presence of tetra hydroxocobaltate, containing Co(II), followed bysubsequent oxidation to Co(III) indicates that Co from NMC was reduced from +3 to +2 during heating in the molten salt in the presence of graphite, despite the acidic conditions of the first composition.

[0403] Example 2

[0404] Target metal recovery from a commercial black mass (622 black mass provided by Company A) was carried out using the process of the disclosure. These further experiments were carried out to investigate the impact of the solubilising salt on the magnetic material recovery. The experiments are shown below in Table 3.

[0405] The samples were prepared in both AI2O3 and nickel crucibles.

[0406] The reductant used in each of the experiments was graphite.

[0407] The composition of the solubilising salt was varied for each sample, and in each case the solubilising salt comprised of alkali hydroxides.

[0408] In each case, magnetic material comprising Ni, Co and Cu metal was recovered. The amount of magnetic material was weighed.

[0409]

[0410] Table 3.Across all comparable experiments, magnetic recovery was consistently higher when KOH was used instead of NaOH, and higher when KOH was added to NaOH mixtures. However, NaOH does still provide a viable option as magnetic material is still produced.

[0411] Example 3

[0412] Target metal recovery from a range of NMC black mass grades was carried out using the process of the disclosure, with conditions according Table 4.

[0413] In each case, the molten salt of the first composition was used as a solvent according to the disclosure. The salt mass was 5000g in each study.

[0414] The salt was mixed with the black mass in the desired ratio in a reactor constructed from stainless steel. The mixture was heated above the melting point of the salt and stirring was initiated with a mechanical agitator. The mixture was then heated to the desired temperature and held for the desired time.

[0415] Heating was then stopped and the salt was allowed to cool forming a solid frozen salt at the bottom of the reactor. Once solidified, 20 L of water was added to the mixture and stirred to aid dissolution. This liquid was then pumped out of the reactor, and a magnetic separation was then conducted to recover a metallic NiCoCu product. Further steps were then carried out to separate and filter the non-magnetic particles, with the Li retained in the aqueous filtrate as Li-ions which were later recovered through methods such as precipitation.

[0416]

[0417] Table 4.Compositions of Company A (1) and Company B (2) black mass (analysis by AGM Analytical) are shown in Table 5.

[0418]

[0419] Table 5.

[0420] Overall, this example shows that a range of NMC black mass grades, ratios of black mass to salt, hold durations, hold temperatures and ramp rates can be used in the process of the present disclosure in order to obtain target metal recovery.

[0421] It further shows that greater yields can be obtained with a greater fraction of KOH vs NaOH and higher ramp rates. Higher hold temperatures also seem to improve yields. Longer hold durations at the target temperature also appear to improve yields, rather than simply time above the minimum reaction temperature.

[0422] All runs (but for comparison 1, 2, 4, and 7) indicate lower ratios of black mass to salt can have the same effectiveness.

[0423] Run 2, relative to all other runs, demonstrates that the process is effective for black mass from different suppliers, and further demonstrates that the process is also effective for lower quality black mass.

[0424] Example 4

[0425] Target metal recovery from an AINiCo magnet was carried out using the process of the disclosure. The AINiCo 5 magnet had the composition shown in Table 6. 12.2 gof AINiCo was exposed to a solubilising salt consisting of KOH in an AI2O3 crucible at 600°C for 100 h to ensure full breakdown of the material.

[0426] The mixture was then allowed to cool until it solidified, and 5 g of graphite (99+ %) was added to the mixture. The mixture was then heated to 600°C and held for 12 h. The mixture was then allowed to cool until it solidified, following which an equivalent mass of water was used to dissolve the salt.

[0427]

[0428] Table 6- Approximate composition of commercially procured AINiCo 5 magnet A metallic powder (2.53 g) was then separated from the mixture using an electromagnet. This material was washed and dried, following which the elemental composition was determined by analysis with the results shown in Table 7. The composition consisted of 55.52 % Ni-Co I 59.98 % Ni-Co-Cu, and the yield was approximately 55%.

[0429]

[0430] Table 7 - Analysis data for recovered metallic powder.

[0431] This example demonstrates that the process can be applied to feedstocks other than Li-ion batteries. The data indicates that aluminium has been almost completely removed from the sample, and iron has been significantly reduced.

[0432] Example 5

[0433] Experiments with aluminium.

[0434] Lab grade LCO feedstock, with no graphite or other impurities present, was exposed to aluminium metal reductant in molten NaOH-KOH (80g) eutectic solubilising salt at 250°C and 420°C. The hydroxide salts were weighed and mixed in the required ratioand transferred to a nickel crucible, along with 20g LCO material. This was placed in a vertical tube furnace and heated to the target temperature while open to atmosphere. Once the target temperature was reached, a roll of aluminium foil (>98%) was placed in the crucible and left to stand for a period of 2 hours. The roll of aluminium foil was then removed and left to cool.

[0435] This example shows that various reductants can be used to obtain the metallic product, in this case aluminium. In both cases, a black, magnetic layer had deposited on the aluminium foil, indicating dissolution and reduction of cobalt to a metallic species. It further shows that reduction can occur under a wide range of temperatures in the molten salt, with demonstration of the process at a reduced temperature of 250°C. From thermodynamic calculations, it is expected that this reaction would occur at any temperature above the melting point of the molten salt. The use of a static reductant further indicates that the molten salt acts as a solubilising salt, enabling diffusion of ionic species to the reductant.

[0436] Example 6

[0437] Experiment with Na-ion black mass.

[0438] Na-ion battery black mass was produced from Na-ion batteries comprising hard carbon and layered oxides of Ni, Mn and Fe. 30 g of this black mass was mixed with 150 g of KOH and heated to 600°C for 12 h in a nickel crucible. The mixture was cooled and solidified then dissolved in water, whereupon it formed a dark green solution. A metallic product was magnetically recovered from the solution. This product is expected to be nickel metal, as this is the only species present which is capable of forming a magnetic metal.

[0439] This example shows that the process can also be applied to Na-ion battery black mass and that hard carbon can be used as a reductant.

[0440] Na-ion battery black mass was sourced from batteries procured commercially with stated composition containing Ni, Mn and Fe oxides, but the composition has not been verified.

Claims

CLAIMS1. A process for recovering a target metal comprising the steps of:i. Providing a first composition as a molten salt, said molten salt comprising a solubilising salt, a reductant and a target metal; andii. Processing the first composition to form a solid comprising the target metal;andiii. Recovering the target metal.

2. The process of claim 1, wherein the first composition comprises a wt% molten salt of 20 wt% or more, such as from 30 wt% or more, 40wt% or more, 50wt% or more or 60wt% or more.

3. The process of claims 1-2 wherein the solubilising salt is a metal hydroxide, preferably the first composition comprises at least one alkali metal hydroxide, optionally wherein the metal hydroxide is selected from the group comprising LiOH, NaOH, KOH, CsOH, RbOH, NaOH-KOH, LiOH-KOH, LiOH-NaOH-KOH, and combinations thereof.

4. The process of claims 1-3 wherein the temperature of the first composition is in the range of from is in the range from 100°C to 1300°C, from 170°C to 1300°C, from 200°C to 1000°C, from 250°C to 800°C, from 300°C to 750°C, from 350°C to 700°C or from 400°C to 650°C.

5. The process of claim 1-4 wherein the reductant comprises a carbon allotrope such as such as graphene, graphite, carbon nanotubes, carbon nanofibers, carbon black, acetylene black, Ketjenblack, Super P, or combination thereof, preferably wherein the reductant comprises graphite.

6. The process of claims 1-5 wherein the target metal is a transition metal, d-block metal, alkali metal, alkali earth metal, and / or combinations thereof, preferably wherein the target metal is selected from the group comprising nickel, manganese, copper, iron, titanium, aluminium, zinc, chromium, molybdenum, vanadium, tin, lead, cadmium, silver, gold, platinum, lithium, sodium, calcium, potassium, magnesium, or combinations thereof.

7. The process of claims 1-6, wherein the target metal is derived from a feedstock comprising a battery waste material and / or a magnetic material.

8. The process of claims 1-7, wherein the reductant and the target metal are derived from a feedstock, optionally wherein the feedstock comprises battery waste material and / or a magnetic waste material.

9. The process of claims 1-8 wherein the first composition comprises at least a stoichiometric ratio of reductant to target metal.

10. The process of claims 1-9 wherein the solid comprising the target metal is an enriched solid having a higher metal mole percentage of the target metal than the metal mole percentage of the target metal in a feedstock from which the target metal was derived.

11. The process of claim 10, wherein the enriched solid comprises a metal mole percentage of the target metal that is at least 1.5 times, at least 2 times, at least 3 times, at least 5 times, or at least 10 times higher than the metal mole percentage of the target metal in the feedstock.

12. The process of claim 1-13 wherein step (ii) comprises:processing the first composition to provide an enriched solid and a residual composition (said residual composition being a molten salt), wherein the enriched solid contains the target metal in enriched form compared to the residual composition; andcooling the residual composition (molten salt) to form a solid residual composition, optionally wherein- the solid residual composition comprises a target metal.

13. The process of any one of claims 10-12, wherein in step (iii) the enriched solid is subjected to a downstream hydrometallurgical process to further purify or separate the target metal.

14. The process of claim 13, wherein the hydrometallurgical process is selected from ammoniacal leaching, acidic sulphate oxidative leaching, chloride leaching, or pressure oxidative leaching.

15. The process of claims 1-12 wherein step (iii) comprises:a. contacting the solid comprising the target metal with an aqueous solution to form an aqueous composition comprising the target metal, and recovering the target metal from the aqueous composition.

16. The process of claims 1-12 wherein the first composition comprises a first target metal and a second target metal, wherein the first target metal is a transition metal, and the second target metal is lithium, and step (iii) comprises:(x) Recovering a transition metal from the aqueous composition in the form of a transition metal hydroxide to form a residual aqueous composition;(y) Adding a carbonate-forming species to the residual aqueous composition to form a lithium carbonate precipitate; and(z) Recovering the lithium carbonate precipitate from the aqueous composition; whereina residual aqueous composition is the aqueous composition depleted of the transition metal recovered in step (x).

17. A process for recovering a target metal comprising the steps of:i. Providing a first composition as a molten salt, said molten salt comprising a solubilising salt, a reductant and a target metal;wherein the solubilising salt is metal hydroxide,wherein the first composition has a temperature in the range of from 100°C to 650°C; andwherein the reductant comprises a carbon allotropeii. Processing the first composition to form a solid comprising the target metal;andiii. Recovering the target metal.

18. The process of claim 17, wherein the target metal is derived from a feedstock and wherein the comprises battery waste material and / or a magnetic waste material.

19. The process of claim 17 or 18, wherein the reductant and the target metal are derived from a feedstock.

20. The process of claims 17-19, wherein the reductant comprises a solid carbon allotrope.

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