Method for extracting a metal from a precursor material

Abstract

There is provided a method (100) for extracting a metal from a precursor material containing an oxide of said metal. The method comprises a solubilizing step of reacting the precursor material with an aqueous reducing agent to form a solution comprising a soluble species containing the metal. The aqueous reducing agent comprises at least one of Ti, Sn, V, Zr, Y, Nb, and Hf. The precursor material is a lithium-ion battery cathode material comprising at least one of Li, Ni or Co.

Description

[0001] RUB-9458-22-3105 (P / 87659.WO01)

[0002] 1

[0003] METHOD FOR EXTRACTING A METAL FROM A PRECURSOR MATERIAL

[0004] The present invention relates to metal extraction from a precursor material.

[0005] In particular, the invention relates to a method for extracting a metal from a precursor material containing an oxide of said metal. The method comprises a solubilizing step of reacting the precursor material with an aqueous reducing agent to form a solution comprising a soluble species containing the metal. The aqueous reducing agent comprises at least one of Ti, Sn, V, Zr, Y, Nb, and Hf.

[0006] It is predicted that in the coming years a greater proportion of automotive vehicle market will consist of full battery electric vehicles, hybrid electric vehicles and plug-in hybrid electric relying on lithium- ion batteries (LIBs). This will result in a significant increase in production of such batteries. In particular, a significant increase in the production of cathodic metals. Such a significant increase in demand of geographically compromised raw materials will result in considerable stress on the existing chain of supply. The recycling of spent lithium-ion batteries involving the recovery of relevant species which are listed as critical raw materials, has been proposed as a suitable approach to alleviate those resource availability issues.

[0007] The isolation of valuable species from spent lithium-ion batteries is a multi-step process that needs to be designed to minimize hazards such as electrical shocks from high energy density electrochemical devices or the existence of toxic and flammable species, for instance the organic electrolyte or the perfluorinated polymer binder. Besides that, whereas elements such as Ni and particularly Co present highest economic value in the lithium-ion battery, they are carcinogenic and mutagenic materials that should be carefully manipulated. As a result, before the extraction of valuable materials, the lithium-ion battery should go through a series of pre-treatments including sorting, stabilization (safe discharging), dismantling, crushing and sieving. The outcome of this process is a solid known as the “black mass”.

[0008] Currently, the two industrial technologies most widely used for the recovery of metals from the black mass are the hydrometallurgical and pyrometallurgical methods. The pyrometallurgical approach involves a high temperature treatment between 1200°C and 1600°C. This has widely been implemented for recycling different battery technologies namely lead-acid batteries or Ni metal-hydride batteries.

[0009] However, in the context of Ni and Co recovery from spent lithium-ion batteries, the pyrometallurgical approach leads to poor yield (below 50%). In contrast, the hydrometallurgical utilises milder conditions and permits the recovery of metal with high purity and yield (>90%).

[0010] The hydrometallurgical process normally involves two independent steps (or a combination of them): i) metal leaching (e.g., solvent extraction or chemical reaction) and ii) purification process (e.g., precipitation or electrolytic processing). The metal leaching step has extensively been RUB-9458-22-3105 (P / 87659.WO01)

[0011] 2 studied and it usually involves batch processing to gradually solubilize the black mass into an aqueous phase. The driving force for the process is the reaction with strong inorganic acids (e.g., hydrochloric acid and / or sulfuric acid).

[0012] However, in order to accelerate the kinetics of the “black mass” solubilization reaction, there is a need for sacrificial agents like organic acids (e.g., acetic acid, citric acid; or malic acid). These species are consumed during the process leading to the formation of CO2 and enabling the undesired formation of carbonate species which might precipitate out if pH is not carefully adjusted.

[0013] More recently, the concept of solvometallurgy was introduced, in which the aqueous phase is replaced by a non-aqueous phase. This promotes selective metal extraction with relatively high solid-to-liquid ratio. However, the purification step requires either the evaporation and condensation of the organic phase or the addition of fresh water. This leads to higher operational cost as well as to undesired by-products and waste management concerns. To this date, the complexity of the purification step has precluded the scaling of solvomethallurgy methods for lithium-ion battery metal recovery up to industrial scale.

[0014] In conclusion, a wide range of different aqueous hydrometallurgical methods are currently employed industrially. However, the existing methods necessitate lengthy batch processes above room temperature due to slow reaction kinetics. This, in conjunction with the imperative consumption of organic and / or inorganic species, leads to a cost that can be a significant proportion of the total lithium-ion battery processing cost.

[0015] It would therefore be beneficial to provide a method for extracting a metal from a precursor material, such as a lithium-ion battery, which is fast, inexpensive, and permits the recovery of metal with high purity and yield.

[0016] Furthermore, it would be beneficial for said method to be suitable for extracting a metal from other precursor materials different from a lithium-ion battery, such as metal-bearing ores. Such metalbearing ores comprising lithium include spodumene, lepidolite, and petalite. As an example, spodumene (LiAISi2Oe) comprises lithium oxide (IJ2O).

[0017] According to the present disclosure, there is provided a method for extracting a metal from a precursor material containing an oxide of said metal, the method comprising a solubilizing step of reacting the precursor material with an aqueous reducing agent to form a solution comprising a soluble species containing the metal; wherein the aqueous reducing agent comprises at least one of Ti, Sn, V, Zr, Y, Nb, and Hf.

[0018] The solubilizing step of reacting the precursor material with an aqueous reducing agent relies on a redox-mediated reaction between the metal oxide and the aqueous reducing agent. To achieve such a reaction, the aqueous reducing agent comprises species with a tendency to form oxides via abstraction of oxygen atoms. This property is referred to as “oxophilicity”. As an example, RUB-9458-22-3105 (P / 87659.WO01)

[0019] 3

[0020] Cobalt and Nickel oxophilicities have been reported as 0.4 and 0.2 respectively. As a result, they will react with species presenting oxophilicity above that value. For example, the oxophilic characteristics of Ti has been reported as 1.0 which would be in alignment with a chemical reaction in which Ti will be able to capture oxygen atoms from the Co or Ni surface, for instance from the metal oxide. Ti, Sn, V, Zr, Y, Nb, and Hf have all been found to be such suitable species for such a reaction. As used herein “Ti, Sn, V, Zr, Y, Nb, and Hf’ may refer to any suitable oxidation states thereof of these species.

[0021] Advantageously, such a method may be carried out at room temperature, and the metal oxide is rapidly dissolved. Furthermore, such a method does not necessitate any sacrificial agent. The solubilizing step may therefore not include use of any sacrificial agent, such as an organic acid (e.g., acetic acid, citric acid; or malic acid).

[0022] The aqueous reducing agent may comprise an aqueous-metal-complex. For example, the aqueous reducing agent may comprise a sulphate, and the soluble species containing the metal may be a metal sulphate. Advantageously, such a reaction with a lithium-ion battery cathode material would generate soluble metal sulphates such as C0SO4, IJ2SO4, LiHSC or NiSC .

[0023] The aqueous reducing agent may comprise Ti. For example, the aqueous reducing agent may comprise Ti(lll). For example, the aqueous reducing agent may comprise Ti(ll). The aqueous reducing agent may comprise Ti2(SO4)3. The solution may comprise 10 % to 20 % by weight Ti2(SO4)3. Advantageously, Ti is widely available and inexpensive in comparison to V, Zr, Y, Nb, and Hf for example.

[0024] The aqueous reducing agent may comprise Sn. For example, the aqueous reducing agent may comprise Sn(ll). The aqueous reducing agent may comprise V. For example, the aqueous reducing agent may comprise V(l I) . The aqueous reducing agent may comprise one or more of the metallic species Zr, Y, Nb, and Hf. The aqueous reducing agent may comprise at least one of Ti, Sn, Zr, Y, Nb, and Hf. The aqueous reducing agent may comprise at least one of Sn, Zr, Y, Nb, and Hf.

[0025] The aqueous reducing agent may be contained within a solution comprising an acid. The acid may be sulphuric acid. The solution may comprise 1 % to 4 % by weight sulphuric acid. The solution may comprise an acid concentration of less than 0.2 Molar. Advantageously, such a solution may reduce the the polymerization of TiOSC and the unwanted precipitation of TiC>2 during the reaction when Ti2(SO4)3is used as a reducing agent.

[0026] The solubilizing step of reacting the precursor material with the aqueous reducing agent may result in the at least one of Ti, Sn, V, Zr, Y, Nb, and Hf remaining in solution after the aqueous reducing agent has reacted with the precursor material. The at least one of Ti, Sn, V, Zr, Y, Nb, and Hf remaining in solution may be the at least one of Ti, Sn, V, Zr, Y, Nb, and Hf species used as a reducing agent in the solubilizing step. The at least one of Ti, Sn, V, Zr, Y, Nb, and Hf remaining in solution may therefore have a greater oxidation state compared to the at least one of Ti, Sn, V, Zr, RUB-9458-22-3105 (P / 87659.WO01)

[0027] 4

[0028] Y, Nb, and Hf of the aqueous reducing agent. As used herein “remaining in solution" means that the at least one of Ti, Sn, V, Zr, Y, Nb, and Hf is dissolved in the solution after the aqueous reducing agent has reacted with the precursor material, and has not precipitated out of the solution. In other words, the solubilizing step of reacting the precursor material with the aqueous reducing agent may result in the formation of a compound, comprising the at least one of Ti, Sn, V, Zr, Y, Nb, and Hf, which is soluble in the solution. The solubilizing step of reacting the precursor material with the aqueous reducing agent may therefore not result in the formation of a compound comprising the at least one of Ti, Sn, V, Zr, Y, Nb, and Hf which is insoluble in the solution. The at least one of Ti, Sn, V, Zr, Y, Nb, and Hf remaining in solution may comprise species of the at least one of Ti, Sn, V, Zr, Y, Nb, and Hf having a higher oxidation state than the at least one of Ti, Sn, V, Zr, Y, Nb, and Hf in the aqueous reducing agent.

[0029] In embodiments in which the aqueous reducing agent comprises Ti, the solubilizing step of reacting the precursor material with the aqueous reducing agent may result in Ti remaining in solution after the aqueous reducing agent has reacted with the precursor material. The Ti remaining in solution may be the Ti species used as a reducing agent in the solubilizing step. The Ti remaining in solution may therefore have a greater oxidation state compared to the Ti of the aqueous reducing agent. For example, in embodiments in which the aqueous reducing agent comprises Ti, the solubilizing step of reacting the precursor material with the aqueous reducing agent may result in the formation of a compound comprising Ti which is soluble in the solution. For example, in embodiments in which the aqueous reducing agent comprises Ti2(SO4)s, the solubilizing step of reacting the precursor material with the aqueous reducing agent may result in the formation of TiOSC . TiOSO4may be soluble in the solution. In embodiments in which the aqueous reducing agent comprises Ti2(SO4)3, the solubilizing step of reacting the precursor material with the aqueous reducing agent may result in the formation of Ti(SO4)2. Ti(SO4)2 may be soluble in the solution. The Ti remaining in solution may therefore comprise Ti(IV). The Ti remaining in solution may therefore comprise Ti having a higher oxidation state, such as Ti(IV), than the Ti in the aqueous reducing agent, such as Ti(lll).

[0030] Advantageously, by ensuring that the at least one of Ti, Sn, V, Zr, Y, Nb, and Hf remains in solution after the aqueous reducing agent has reacted with the precursor material, the aqueous reducing agent may be easily regenerated in a subsequent regeneration step, as outlined below.

[0031] The at least one of Ti, Sn, V, Zr, Y, Nb, and Hf may remain in solution throughout the method disclosed herein. For example, the at least one of Ti, Sn, V, Zr, Y, Nb, and Hf may remain in solution following the solubilizing step. The at least one of Ti, Sn, V, Zr, Y, Nb, and Hf may remain in solution following the step of reacting the soluble species containing the metal to precipitate an insoluble species containing the metal. The at least one of Ti, Sn, V, Zr, Y, Nb, and Hf may remain in solution following the step of extracting the insoluble species. The at least one of Ti, Sn, V, Zr, Y, Nb, and Hf may remain in solution following the step of regenerating the aqueous reducing agent. RUB-9458-22-3105 (P / 87659.WO01)

[0032] 5

[0033] The solubilizing step of reacting the precursor material with an aqueous reducing agent may be performed at a temperature between 273 K and 310 K. The solubilizing step of reacting the precursor material with an aqueous reducing agent may be performed at a temperature substantially equal to 298 K. The solubilizing step of reacting the precursor material with an aqueous reducing agent may be performed at a pressure substantially equal to atmospheric pressure. Advantageously, such a reaction has been found to be fast and result in a high yield even at room temperature and atmospheric pressure.

[0034] The precursor material may be a mixed-metal oxide. For example, the mixed-metal oxide may comprise a plurality of metal species in addition to oxygen. In this case, the method may comprise a solubilizing step of reacting the mixed-metal oxide with an aqueous reducing agent to form a solution comprising one or more soluble species, each soluble species containing the one or more of the metals from the mixed-metal oxide.

[0035] The precursor material may be a lithium-ion battery cathode material. As used herein, a lithium-ion battery cathode material may refer to a material which has been extracted from a lithium-ion battery, in particular from a cathode of a lithium-ion battery. The extraction from a lithium-ion battery may occur during recycling of the lithium-ion battery. The lithium-ion battery cathode material may comprise at least one of Li, Ni or Co. Advantageously, such a method may be particularly economically beneficial, due to the high cost of Li, Ni and Co. The precursor material may be a component of a black mass. The black mass may be in the form of a powder or powdery residue. The precursor material may therefore be in the form of a powder or powdery residue. The precursor material may therefore be dispersed within the rest of the black mass. The black mass may be the result of processing of at least one lithium-ion battery. The black mass may comprise lithium-ion battery cathode material and lithium-ion battery anode material. The black mass may comprise at least one other component of a lithium-ion battery. The processing of the at least one lithium-ion battery may comprise one or more pre-treatments including sorting, stabilization (safe discharging), dismantling, crushing and / or sieving.

[0036] For example, the precursor material may comprise lithium cobalt oxide. The precursor material may comprise UACOB02, wherein 0.1 < A < 1 and 0.8 < B < 1 . A may be substantially equal to 1 . B may be substantially equal to 1 . A + B may be substantially equal to 2. The precursor material may comprise UC0O2.

[0037] Alternatively or additionally, the precursor material may comprise lithium nickel manganese cobalt oxide. The precursor material may comprise LicNiDCoEMnF02, wherein 0.1 < C <1 , 0.01 < D < 1 , 0.01 < E < 1 , and 0.01 < F < 1 . C may be substantially equal to 1 . D + E + F may be substantially equal to 1. C + D + E + F may be substantially equal to 2. The precursor material may comprise LiNio.8Coo.1Mno.1O2. RUB-9458-22-3105 (P / 87659.WO01)

[0038] 6

[0039] Alternatively or additionally, the precursor material may comprise lithium nickel cobalt aluminium oxide. The precursor material may comprise LicNinCojAI^, wherein 0.1 < G <1 , 0.01 < H < 1 , 0.01 < J < 1 , and 0.01 < K < 1 . G may be substantially equal to 1 . H + J + K may be substantially equal to 1 . G + H + J + K may be substantially equal to 2. The precursor material may comprise LiNi0.8Co0.15AI0.05O2.

[0040] The metal from the precursor material may comprise one or more of Cobalt, Manganese, Aluminium, Nickel, or Lithium.

[0041] The method may further comprise the step of reacting the soluble species containing the metal to precipitate an insoluble species containing the metal. Formation of an insoluble species containing the metal allows for the metal to be easily extracted from the solution, where the insoluble species can undergo further processing steps to recycle the metal.

[0042] The step of reacting the soluble species containing the metal may comprise reacting the soluble species with a hydroxide to form an insoluble metal hydroxide, the insoluble metal hydroxide comprising the metal from the precursor material. The hydroxide may be NaOH or KOH for example. When the metal from the precursor material is Cobalt, the metal hydroxide may be CO(OH)2. Advantageously, this method of reacting the soluble species is straightforward and inexpensive. However, this method of reacting the soluble species requires careful control of pH to selectively precipitate valuable species such as Co(OH)2 while avoiding contamination by other metal such as Ni(OH)2. Furthermore such a step would result in the formation of TiO2 when Ti is used in the reducing agent. TiO2 is a highly stable metal oxide, and the regeneration of a soluble Ti-species would then require reaction of the TiO2with hot and concentrated sulfuric acid, and this would significantly increase the operational cost.

[0043] It would therefore be further beneficial to provide an alternative step of reacting the soluble species containing the metal which does not include such drawbacks. As an example of such an alternative, the step of reacting the soluble species containing the metal may comprise reacting the soluble species with oxalic acid ((COOH)2) to form an insoluble oxalate, the insoluble oxalate comprising the metal from the precursor material. When the metal from the precursor material is Cobalt, the insoluble oxalate may be C0C2O4 (co-oxalate). Advantageously, Ti-oxalate (^2(6204)3) will remain in solution whereas Co-oxalate is an insoluble precipitate. This means that Co may be easily extracted from the solution without also extracting the Ti. Similarly, when the metal from the precursor material is Manganese, Aluminium, or Nickel, the insoluble oxalate may be MnC2O4, Al2(C2O4)3, or NiC2O4 respectively. Advantageously, MnC2O4, Al2(C2O4)s, or NiC2O4 are insoluble precipitates. This means that Mn, Al, or Ni may be easily extracted from the solution without also extracting the Ti.

[0044] The step of reacting the soluble species containing the metal may comprise reacting the soluble species with a carbonate to form an insoluble metal carbonate, the insoluble metal carbonate RUB-9458-22-3105 (P / 87659.WO01)

[0045] 7 comprising the metal from the precursor material. For example, the step of reacting the soluble species containing the metal may comprise reacting U2SO4 or UHSO4 with a carbonate such as K2CO3 to form IJ2CO3. As Ti (III) would again remain in solution, this means that any of Li may be easily extracted from the solution without also extracting the Ti(l 11). The step may be performed in addition to reacting further soluble species containing other metals to precipitate further insoluble species containing said other metals, as outlined above for Cobalt, Manganese, Aluminium, or Nickel for example.

[0046] The step of reacting the soluble species containing the metal may be performed at a temperature between 273 K and 310 K. The step of reacting the soluble species containing the metal may be performed at a temperature substantially equal to 298 K. The step of reacting the soluble species containing the metal may be performed at a pressure substantially equal to atmospheric pressure. Advantageously, such a reaction has been found to be fast and result in a high yield even at room temperature and atmospheric pressure.

[0047] The method further may further comprise the step of extracting the insoluble species. For example, filtering the insoluble species from the solution. The insoluble species can then undergo further processing steps to recycle the metal. When the insoluble species comprises an oxalate, such as Co-oxalate, the step of extracting the insoluble species may comprise calcination of the insoluble species to generate a metal oxide. The metal oxide may be Cobalt oxide.

[0048] When the metal from the precursor material comprises Li, the method may further comprise the step of extracting Li from the soluble species. The step of extracting Li from the soluble species may comprise using a lithium-ion selective membrane configured to selectively transport Li ions. This step may comprise Li ions from a solution containing the soluble species pass from a first volume, through the lithium-ion selective membrane, to a second volume. Such lithium-ion selective membranes are known in the art, and disclosed in WO 2012 / 058684 A2. Again, Ti (III) would remain in solution in the first volume, and would not be transported across the lithium-ion selective membrane. This means that Li may be easily extracted from the solution without also extracting the Ti. The Ti may then be regenerated into the aqueous reducing agent, as outlined below.

[0049] The method may further comprise the step of regenerating the aqueous reducing agent. The implementation of solid-to-liquid reaction between the aqueous reducing agent and the precursor material might be a valuable approach for metal recovery by itself. However, the chemistry here proposed is compatible with other technology embodiments with a series of advantages. For example a continuous or semi-continuous extraction process. Such a step may advantageously further reduce the cost of the method due to the aqueous reducing agent being reused. For example, the method may further comprise repeating the solubilizing step of reacting the precursor material with aqueous reducing agent using the regenerated aqueous reducing agent. RUB-9458-22-3105 (P / 87659.WO01)

[0050] 8

[0051] The step of regenerating the aqueous reducing agent may comprise reacting a metal oxide species formed from the aqueous reducing agent with a chemical. Such chemicals may have a lower redox potential than Ti(IV) / Ti(lll). The chemical may comprise metals such as Zn, Fe, Sn or Al. The chemical may comprise soluble species such as V(ll), quinone derivatives and other organic molecules or redox active polymers. The chemical may comprise Lithium Aluminium hydride LiAl H4, a metal borohydride MBH4 (in which M is an alkali metal; Li, Na, K, Rb or Cs), or hydrazine.

[0052] The step of regenerating the aqueous reducing agent may comprise introducing the solution into an electrochemical cell, the electrochemical cell comprising a cathode and an anode. The step of regenerating the aqueous reducing agent may comprise performing the solubilizing step in an electrochemical cell, the electrochemical cell comprising a cathode and an anode. Performing the solubilizing step in an electrochemical cell may comprise performing the solubilizing step in fluid communication with the cathode. The step of regenerating the aqueous reducing agent may comprise regenerating the aqueous reducing agent at the cathode.

[0053] Regenerating the aqueous reducing agent using the electrochemical cell may comprise reducing Ti(IV) to Ti(lll) at the cathode. In the extraction of lithium-ion battery cathode material (for example LiCoC>2), the solubilizing step of reacting the precursor material with an aqueous reducing agent would therefore occur with the transformation of Ti2(SC>4)3 into TiOSC which represents a change in oxidation state from Ti(lll) to Ti(IV). The redox potential associated the Ti(IV) / Ti(l 11) transformation is E°= 0.1V compared to the standard hydrogen electrode (SHE). This potential is significantly higher than that required to further reduce other by-products from the solubilizing step such as Ni2+(E°= -0.25V vs SHE), Co2+(E°= -0.28V vs SHE) , Al3+(E°= -1 ,66V vs SHE) or Mn2+(E°= -1 ,18V vs SHE). This means that an electrochemical flow reactor can be engineered to selectively regenerate Ti(lll) from Ti(IV) in the form of Ti2(SC>4)3 in a selective manner. As a result, less aqueous reducing agent may be used and the solution may be cycled to re generate the aqueous reducing agent.

[0054] Regenerating the aqueous reducing agent using the electrochemical cell may comprise oxidising hydrogen at the anode. The operation of this system would be analogous to that of a fuel cell therefore leading to the generation of power at 0.1V.

[0055] Regenerating the aqueous reducing agent using the electrochemical cell may comprise oxidising water at the anode. It can however be understood that any other suitable oxidising reaction may take place at the anode. For example, regenerating the aqueous reducing agent using the electrochemical cell may comprise oxidising an organic compound such as ethanol, methanol, propanol, glucose, a sacrificial agent such as V(l I) , quinone derivatives and redox active polymers, or another metal at the anode. The other metals may comprise Zn, Fe, Sn, Al, or any other metals with a redox potential lowerthan that of the Ti(IV) / Ti(l 11) transformation. . Regenerating the aqueous reducing agent using the electrochemical cell may comprise oxidising hydrogen or hydrogen peroxide at the anode. RUB-9458-22-3105 (P / 87659.WO01)

[0056] 9

[0057] The Invention will be described, by way of example only, in the following Figures in which:

[0058] Figure 1 shows a schematic of a method for extracting a metal from a precursor material containing an oxide of said metal according to the present disclosure;

[0059] Figures 2a and 2b show the results of the solubilizing step of the method of Figure 1 when the precursor powder is LiCo02;

[0060] Figures 3a and 3b show the results of the solubilizing step of the method of Figure 1 when the precursor powder is LiNio.8Coo.1Mno.1O2;

[0061] Figures 4a and 4b show the results of the solubilizing step of the method of Figure 1 when the precursor powder is LiNi0.8Co0.15AI0.05O2;

[0062] Figure 5 shows a schematic of a first alternative method for extracting a metal from a precursor material containing an oxide of said metal according to the present disclosure;

[0063] Figure 6 shows a schematic of an electrochemical cell for use with the method illustrated in Figure 5; and

[0064] Figure 7 shows a schematic of a second alternative method for extracting a metal from a precursor material containing an oxide of said metal according to the present disclosure.

[0065] Figure 1 shows a schematic of a method 100 for extracting a metal from a precursor material containing an oxide of said metal according to the present disclosure.

[0066] The method 100 comprises a solubilizing step 101 of reacting the precursor material with an aqueous reducing agent to form a solution comprising a soluble species containing the metal.

[0067] In the illustrated example, the solubilizing step 101 comprises a solution of an aqueous reducing agent to a reaction vessel and maintaining under magnetic stirring at ambient conditions (both pressure and temperature). In the present example, 50 milliliters of a solution of Ti2(SO4)3 was added to a reaction vessel and maintaining under magnetic stirring at ambient conditions (both pressure and temperature). The solution of Ti2(SO4)s in the present example comprises 15 % by weight Ti2(SC>4)3, and 1 % to 4 % sulfuric acid.

[0068] The solubilizing step 101 further comprises adding a precursor material (such as lithium-ion battery cathode material) to the solution. The present example, between 2.50 and 3.25 grams of LiCoC>2, LiNio.8Coo.1Mno.1O2, or LiNi0.8Co0.15AI0.05O2 powder was added to the reaction vessel while the solution was stirred leading to a solid-to-liquid ratio between 50 and 65 grams per liter. The precursor material may also be a component of a black mass resulting from of processing of at least one lithium-ion battery. The black mass may therefore comprise lithium-ion battery cathode material (the precursor material) and other materials such as lithium-ion battery anode material. RUB-9458-22-3105 (P / 87659.WO01)

[0069] 10

[0070] During the solubilizing step 101 the aqueous reducing agent reacts with the precursor material. An example of a reaction which takes place during the solubilizing step 101 according to the present example is Ti2(SC>4)3 + LiCoC>2 = 2TiOSC>4 + C0SO4. In this example, Li is solubilized as Li2SC>4 or LiHSC , with H2SO4 consumed in the reaction. It can be understood that other inorganic acids such as HCI may be used instead, which would lead to the solubilization of Li as LiCI instead. C0SO4 is soluble, so the Co from the precursor material is successfully solubilized. This reaction includes the oxidation of Ti(lll) to Ti(IV).

[0071] Figures 2a and 2b show the results of the solubilizing step 101 of the method of Figure 1 when the precursor material is UC0O2. Figure 2a shows an example comprising a solid-to-liquid ratio of 50 grams of precursor material per liter. Figure 2b shows an example comprising a solid-to-liquid ratio of 65 grams of precursor material per liter. To confirm that the precursor material is solubilized during the solubilizing step 101 , aliquots were taken at defined intervals of time for metal solubilization quantification (at 0, 3, 7, 15, 30 and 60 minutes). The magnetic stirring was stopped 30 seconds before the aliquot was taken to avoid removing suspended solids. Each aliquot was diluted 105times with 0.1 M ultra-pure HNO3 (70%, purified >99.999%), and inductively coupled plasma mass spectrometry was used to determine the quantity of metal in each aliquot. A calibration curve was conducted for each element employing standardized solutions. The results illustrated in Figures 2a and 2b show that Co and Li are substantially entirely solubilized after 60 minutes.

[0072] Figures 3a and 3b show the results of the solubilizing step of the method of Figure 1 when the precursor powder is LiNio.8Coo.1Mno.1O2. A reaction which takes place during the solubilizing step 101 according to this example is Ti2(SO4)3 + LiNio.8Coo.1Mno.1O2 = 2TiOSO4 + O.IC0SO4 + 0.1 MnSO4 + 0.8NiSO4. Similarly to as described above, Li is solubilized as U2SO4 or UHSO4, with H2SO4 consumed in the reaction. C0SO4, MnSO4, and NiSO4, are soluble, so the Co, Mn and Ni from the precursor material is successfully solubilized. Figure 3a shows an example comprising a solid-to-liquid ratio of 50 grams of precursor material per liter. Figure 3b shows an example comprising a solid-to-liquid ratio of 65 grams of precursor material per liter. The method used to obtain such data is substantially identical to that outlined above with respect to Figure 2a and 2b. Again, the results illustrated in Figures 3a and 3b show that Co, Li, Ni and Mn are solubilized, and reach a plateau in solubilization after less than 30 minutes.

[0073] Figures 4a and 4b show the results of the solubilizing step of the method of Figure 1 when the precursor powder is LiNi0.sCo0.15AI0.05O2. A reaction which takes place during the solubilizing step 101 according to this example is Ti2(SO4)3 + LiNi0.8Co0.15AI0.05O2 = 2TiOSO4 + O.I 5C0SO4 + 0.025Al2(S04)3 + 0.8NiSO4. Similarly to as described above, Li is solubilized as U2SO4 or UHSO4, with H2SO4 consumed in the reaction. C0SO4, AISO4, and NiSO4, are soluble, so the Co, Al and Ni from the precursor material is successfully solubilized. Figure 4a shows an example comprising a solid-to-liquid ratio of 50 grams of precursor material per liter. Figure 4b shows an example RUB-9458-22-3105 (P / 87659.WO01)

[0074] 11 comprising a solid-to-liquid ratio of 60 grams of precursor material per liter. The method used to obtain such data is substantially identical to that outlined above with respect to Figure 2a and 2b. Again, the results illustrated in Figures 4a and 4b show that Co, Li, Ni and Al are solubilized, and reach a plateau in solubilization after approximately 30 minutes.

[0075] The method 100 illustrated in Figure 1 further comprises a step 102 of reacting the soluble species of NiSC , AISO4, MnSC , Li2SC>4, UHSO4, orCoSC to precipitate an insoluble species containing the metal. This step 102 allows for the metal to be easily extracted from the solution, where the insoluble species can undergo further processing steps to recycle the metal. The step 102 of reacting the soluble species containing the metal may comprise a number of different chemical reactions depending on which metal is to be extracted. For example, step 102 may comprise reacting the soluble species with a hydroxide to form an insoluble metal hydroxide. In the present example however, when the metal is Co, Ni, Mn or Al, the step 102 comprises reacting the soluble species of C0SO4 NiSO4, AISO4 or MnSO4with oxalic acid ((COOH)2) to form an insoluble oxalate of C0C2O4, NiC2O4, Al2(C2O4)s, or MnC2O4 respectively. When the oxalic acid is added to the solution, the precipitation of the insoluble oxalate is rapid.

[0076] In the present example, when the metal is Li, the step 102 comprises reacting the soluble species of U2SO4 or LiHSO4with a carbonate such as K2CO3 to form an insoluble metal carbonate such as Li2COs.

[0077] The step 102 may comprise multiple reactions as outlined herein be performed for reacting soluble species containing multiple different metals to precipitate different insoluble species containing said different metals, as outlined above for Cobalt, Manganese, Aluminium, or Nickel for example. For example, the step 102 may comprise reacting two or more of the soluble species of NiSO4, AISO4, MnSO4, U2SO4, UHSO4, or CoS04 to precipitate two or more insoluble species containing the corresponding metals. For example, the mix of soluble species resulting from the solubilization step 101 may be reacted first with oxalic acid and subsequently with a carbonate such as K2CO3 to form multiple insoluble species as outlined above.

[0078] Again, this step 102 is performed at ambient conditions (both pressure and temperature). The method 100 further comprise the step 103 of extracting the insoluble species. In the present example, the step 103 of extracting the insoluble species comprises filtering the insoluble Cooxalate from the solution. The step 103 then comprises calcination of the Co-oxalate to form Cobalt oxide and carbon dioxide. The Cobalt oxide can then be reused, for example in the manufacture of lithium-ion batteries. Similar extraction may be carried out for the insoluble species of NiC2O4, Al2(C2O4)3, or MnC2O4, and for U2CO3.

[0079] Figure 5 shows a schematic of a first alternative method 500 for extracting a metal from a precursor material containing an oxide of said metal according to the present disclosure. The first alternative RUB-9458-22-3105 (P / 87659.WO01)

[0080] 12 method 500 is substantially identical to the method 100 described in Figure 1 , so will be described with respect to its differences only.

[0081] The first alternative method 500 comprises a step 504 of regenerating the aqueous reducing agent. The step of regenerating the aqueous reducing agent comprises introducing the solution from the solubilizing step 101 into an electrochemical cell, the electrochemical cell comprising a cathode and an anode; and regenerating the aqueous reducing agent at the cathode. In the present example where Ti2(SC>4)3 is used as the aqueous reducing agent, Ti(IV) is reduced to Ti(lll) at the cathode. Following the step 500 of regenerating the Ti(lll), the solution from the electrochemical cell is reintroduced into the reaction vessel for the solubilizing step 101 , after which further precursor material is added. This allows for the maximisation of the concentration of Cobalt, and other soluble metals, in solution as the aqueous reducing agent is regenerated and reused. The first alternative method 500 may therefore be referred to as a semi-continuous extraction process.

[0082] Figure 6 shows a schematic of an electrochemical cell 600 for use with the method illustrated in Figure 5. The electrochemical cell 600 comprises an anode 610 and a cathode 612. The anode 610 is separated from the cathode 612 by an electrolyte membrane 614 which allows the passage of ions. The anode 610 is also electrically connected to the cathode 612 via a wire and electrical device, e.g. a resistor 628.

[0083] In use, a standard hydrogen electrode is set up at the anode 610. A supply of hydrogen 616 is provided to a portion 620 of the electrochemical cell 600 adjacent to the anode 610. The hydrogen is oxidised at the anode 610 to form hydrogen ions. Excess hydrogen ions 624 are removed from the portion 620 of the electrochemical cell 600.

[0084] Simultaneously, the solution 618 from the solubilizing step 101 is supplied to a portion 622 of the electrochemical cell 600 adjacent to the cathode 612. The solution 618 from the solubilizing step 101 contains Ti(IV) ions from the used reducing agent. Ti(IV) ions are reduced at the cathode 612 to regenerate Ti(lll) ions. Excess Ti(lll) ions 626 are removed from the portion 622 of the electrochemical cell 600.

[0085] The redox potential associated the Ti(IV) / Ti(lll transformation is E°= 0.1 V compared to the standard hydrogen electrode (SHE). The operation of this electrochemical cell 600 is therefore analogous to that of a fuel cell, leading to the generation of power at 0.1 V in the resistor 628. It can be understood that the power may be harnessed and used for other purposes. Additionally, it can be understood that any other suitable oxidising reaction may instead take place at the anode. For example, regenerating the aqueous reducing agent using the electrochemical cell may comprise oxidising water, an organic compound such as ethanol, methanol, propanol, glucose, a sacrificial agents such as V(l I), quinone derivatives and redox active polymers, or another metal at the anode. The other metals may comprise Zn, Fe, Sn, Al, or any other metals with a redox potential lower than that of the Ti(IV) / Ti(lll) transformation. RUB-9458-22-3105 (P / 87659.WO01)

[0086] 13

[0087] Figure 7 shows a schematic of a second alternative method 700 for extracting a metal from a precursor material containing an oxide of said metal according to the present disclosure. The first alternative method 500 is substantially identical to the first alternative method 500 described in Figure 5, so will be described with respect to its differences only. The second alternative method 700 comprises carrying out the solubilizing step 701 in the electrochemical cell 600. Specifically, the solubilizing step 701 is carried out in a reaction vessel in fluid communication with the portion 622 of the electrochemical cell 600 adjacent to the cathode 612. The solution 618 from the solubilizing step 701 is continuously supplied to the portion 622 of the electrochemical cell 600 adjacent to the cathode 612, and the regenerated aqueous reducing agent in the form of Ti(lll) ions 626 is continuously reintroduced into the reaction vessel. The step 704 of regenerating the aqueous reducing agent therefore occurs simultaneously and concurrently with the solubilizing step 701 , as the aqueous reducing agent in the form of Ti2(SO4)s is continuously regenerated during the solubilizing step 701 . The second alternative method 700 may therefore be referred to as a semi-continuous extraction process.

Claims

RUB-9458-22-3105 (P / 87659.WO01)14Claims1 . A method (100, 500, 700) for extracting a metal from a precursor material containing an oxide of said metal, the method comprising a solubilizing step (101 , 701) of reacting the precursor material with an aqueous reducing agent to form a solution comprising a soluble species containing the metal; wherein the aqueous reducing agent comprises at least one of Ti, Sn, V, Zr, Y, Nb, andHf, and wherein the precursor material is a lithium-ion battery cathode material comprising at least one of Li, Ni or Co.

2. The method (100, 500, 700) according to claim 1 , wherein the aqueous reducing agent comprises an aqueous-metal-complex.

3. The method (100, 500, 700) according to claim 1 or 2, wherein the aqueous reducing agent comprises a sulphate, and wherein the soluble species containing the metal is a metal sulphate.

4. The method (100, 500, 700) according to any preceding claim wherein the aqueous reducing agent comprises Ti(lll).

5. The method (100, 500, 700) according to claim 4, wherein the aqueous reducing agent comprises Ti2(SC>4)3.

6. The method (100, 500, 700) according to any preceding claim, wherein the precursor material comprises UACOBC^, wherein 0.1 < A < 1 and 0.8 < B < 1.

7. The method (100, 500, 700) according to any preceding claim, wherein the precursor material comprises LicNiDCoEMnF02, wherein 0.1 < C <1 , 0.01 < D < 1 , 0.01 < E < 1 , and 0.01 < F < 1.

8. The method (100, 500, 700) according to any preceding claim, wherein the precursor material comprises LicNinCojAI^, wherein 0.1 < G <1 , 0.01 < H < 1 , 0.01 < J < 1 , and 0.01 < K < 1.

9. The method (100, 500, 700) according to any preceding claim, wherein the at least one of Ti, Sn, V, Zr, Y, Nb, and Hf remains in solution following the solubilizing step (101 , 701).

10. The method (100, 500, 700) according to any preceding claim, wherein the method further comprises a step (102) of reacting the soluble species containing the metal to precipitate an insoluble species containing the metal.RUB-9458-22-3105 (P / 87659.WO01)1511 . A method (100, 500, 700) according to claim 10, wherein the step (102) of reacting the soluble species containing the metal comprises reacting the soluble species with oxalic acid to form an insoluble oxalate, the insoluble oxalate comprising the metal from the precursor material.

12. The method (100, 500, 700) according to claim 11 , wherein the metal from the precursor material is Cobalt, and wherein the insoluble oxalate is C0C2O4.

13. The method (100, 500, 700) according to any one of claims 10 to 12, wherein the step (102) of reacting the soluble species containing the metal is performed at a temperature substantially equal to 298 K, and wherein the step (102) of reacting the soluble species containing the metal is performed at a pressure substantially equal to atmospheric pressure.

14. The method (100, 500, 700) according to any one of claims 10 to 13, wherein the method further comprises the step (103) of extracting the insoluble species.

15. The method (100, 500, 700) according to any preceding claim, wherein the aqueous reducing agent is contained within a reducing solution comprising an acid.

16. The method (100, 500, 700) according to claim 15, wherein the acid is sulphuric acid, and wherein the reducing solution comprises 1 % to 4 % by weight sulphuric acid.

17. The method (100, 500, 700) according to claim 15 or 16, wherein the reducing solution comprises 10 % to 20 % by weight Ti2(SC>4)3.

18. The method (100, 500, 700) according to any preceding claim, wherein the solubilizing step (101 , 701) of reacting the precursor material with an aqueous reducing agent is performed at a temperature between 273 K and 310 K, and wherein the solubilizing step (101 , 701) of reacting the precursor material with an aqueous reducing agent is performed at a pressure substantially equal to atmospheric pressure.

19. The method (500, 700) according to any preceding claim, wherein the method further comprises the step (504, 704) of regenerating the aqueous reducing agent.

20. The method (500, 700) according to claim 19, wherein the method further comprises repeating the solubilizing step (101 , 701) of reacting the precursor material with aqueous reducing agent using the regenerated aqueous reducing agent.

21. The method (500) according to claim 19 or 20, wherein the step (504) of regenerating the aqueous reducing agent comprises: introducing the solution into an electrochemical cell (600), the electrochemical cell (600) comprising a cathode (612) and an anode (610); andRUB-9458-22-3105 (P / 87659.WO01)16 regenerating the aqueous reducing agent at the cathode (612).

22. The method (700) according to claim 19 or 20, wherein the step (704) of regenerating the aqueous reducing agent comprises: performing the solubilizing step (701) in an electrochemical cell (600), the electrochemical cell (600) comprising a cathode (612) and an anode (610); and regenerating the aqueous reducing agent at the cathode (612).

23. The method (500, 700) according to claim 21 or 22, wherein regenerating the aqueous reducing agent using the electrochemical cell (600) comprises reducing Ti(IV) to Ti(lll) at the cathode (612).

24. The method (500, 700) according to any one of claims 21 to 23, wherein regenerating the aqueous reducing agent using the electrochemical cell (600) comprises oxidising hydrogen at the anode (610).

25. The method (500, 700) according to any one of claims 21 to 23, wherein regenerating the aqueous reducing agent using the electrochemical cell (600) comprises oxidising water at the anode (610).

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