WO2025193108A1

WO2025193108A1 - Metal recovery process

Info

Publication number: WO2025193108A1
Application number: PCT/NZ2025/050025
Authority: WO
Inventors: Caitlin RYAN; Shereez ALI; Folaranmi AKOGUN; Ian Hsu; David Young
Original assignee: Mint Innovation Ltd
Current assignee: Mint Innovation Ltd
Priority date: 2024-03-13
Filing date: 2025-03-13
Publication date: 2025-09-18
Anticipated expiration: 2026-09-13

Abstract

The invention relates to methods for selectively recovering valuable metals including lithium, nickel, and/or cobalt from feedstock, such as a waste feedstock such as end-of-life lithium-ion batteries, and in particular from waste streams such as black mass derived in whole or in part from NMC type cathode material from such batteries.

Description

METAL RECOVERY PROCESS

TECHNICAL FIELD

The invention relates to methods for selectively recovering valuable metals including lithium, nickel or cobalt from feedstock, such as waste including waste or end-of-life lithium-ion batteries, and in particular from waste streams such as black mass derived in whole or in part from NMC type cathode material from such batteries.

BACKGROUND OF THE INVENTION

The following includes information that may be useful in understanding the present inventions. It is not an admission that any of the information provided herein is prior art, or relevant, to the presently described or claimed inventions, or that any publication or document that is specifically or implicitly referenced is prior art. Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.

There is an abundance of materials containing desirable metals, often in trace amounts, but due to the relative scarcity of the desired metal(s) relative to the non-metals or contaminating undesired metals present, recovering these desirable metals in efficient, environmentally safe ways is extremely challenging. For example, the removal of toxic metal ions from aqueous liquid waste streams is a significant challenge for a wide range of industries.

Recovering metals from feedstocks such as waste streams is, however, often economically prohibitive. Factors that influence the viability of any recovery process include the metal concentration of a feedstock (and hence the amount of feedstock required for processing); the presence of impurities such as other metals or refractory materials; the reagents and/or energy required; and the volume of effluent or other waste that is generated. There is therefore a place for alternative solutions that aim to mitigate at least some of these problems, thereby improving the economics for the recovery of metals from low-grade or recalcitrant feedstocks.

Traditional techniques for refining or recovering metals include pyrometallurgy and hydrometallurgy. In pyrometallurgy, a feedstock is smelted at high temperature (typically in the presence of a suitable reductant and/or catalyst). This requires a non-trivial energy input and associated emissions, and therefore there is a practical minimum metal concentration required in a feedstock. In hydrometallurgy, the feedstock is treated with a lixiviant solution that leaches the desired metal (specifically or otherwise) into an ionic or complexed soluble form. Subsequent steps are required to recover the target metal(s) from solution (e.g. electrowinning). Depending on the temperature and pressure requirements for leaching, this approach may allow for lower grade feedstocks to be processed in comparison to pyrometallurgy. Consideration needs to be made for the possible use of corrosive (e.g. acidic) or toxic (e.g. cyanide) solutions; any consumption of solution components during feedstock treatment; and dealing suitably with waste effluent. Pyrometallurgy and hydrometallurgy techniques are not mutually exclusive, and may be used sequentially over multiple steps to refine specific metals.

Hydrometallurgical techniques have been explored in an effort to recover traces of lithium from waste streams such as black mass. Existing hydrometallurgical methods of recovering lithium have a number of issues, including the use of acidic leaching solutions that cannot be readily reused, and the production of large amounts of salt and wastewater byproducts. The present invention seeks to provide a method of recovering one or more target metals from a feedstock, such as waste lithium-ion batteries (LIB) or a waste stream derived therefrom such as black mass, using selective recovery techniques, for example to complement or replace existing approaches, or at least provide the public with a useful choice in this regard.

The invention relates to a process for the recovery of lithium, optionally together with one or more other target metals, from a feedstock, such as a waste stream including, for example, black mass from waste or end-of-life lithium-ion batteries.

It is anticipated that the present invention and this disclosure will lead to the capture of value from low-grade or waste streams of metal that are currently neglected, and/or provide for low cost, economically viable, energy efficient, and/or environmentally sound alternatives to existing approaches.

SUMMARY OF THE INVENTION

The present invention relates to methods for recovering one or more desirable metals (referred to herein as "target metals") from metal-containing feedstocks, such as but not limited to waste material such as electronic waste or waste streams. More particularly, the invention relates to methods for recovering lithium, optionally together with one or more other target metals, from waste lithium-ion batteries or a waste stream derived from lithium-ion batteries, such as black mass.

The invention accordingly generally relates to methods of recovering one or more target metals from a leachate containing target metal or target metals (usually referred to herein as a target metalpregnant solution) selectively over other metals that may be or are present in solution. This leaves a target metal-barren solution containing lower, and in particularly contemplated examples essentially no target metal(s), or indeed no target metal(s).

Particularly contemplated examples of the invention comprise subjecting the waste material to an ammonia/ammonium salt leach in the presence of a metallic reductant, such as for example iron, copper, or aluminium, followed by oxidation of the solution. This approach uses an ammonia solution in combination with this metallic reductant to impose value selectivity in the leach. Additionally due to the meta -stability of iron and aluminium in ammonia solutions, the reductant does not build up in the solution. As no soluble by-products are left in solution, the leaching solution can be reused repeatedly with no adverse effects.

Representative examples of this method result in a solution that contains only the valuable components of black mass predominantly in the form of I ithium(I), hexaamminenickel(II), and hexaamminecobalt(III).

In certain examples, the methods target the recovery of lithium, cobalt, and/or nickel from black mass.

In one aspect, the invention relates to a method of recovering one or more target metal(s) from electronic waste, the method comprising subjecting the waste material to an ammonia/ammonium salt leach in the presence of a metallic reductant, such as metallic iron, metallic copper, or metallic aluminium, followed by oxidation of the solution.

In another aspect, the invention relates to a method of recovering one or more target metals from a feedstock, the method comprising: a) providing a feedstock, said feedstock comprising at least one target metal and one or more non-target metals; b) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises: i) ammonia; and ii) one or more ammonium salts; and ill) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) separating the target metal-pregnant solution from the one or more precipitated non-target metals; and e) recovering the at least one target metal from the target metal-pregnant solution.

In one example, the method of recovering one or more target metals from a feedstock comprises: a) providing a feedstock, said feedstock comprising at least one target metal and one or more non-target metals; b) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises: i) ammonia; and ii) one or more ammonium salts; and ill) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) contacting the target metal-pregnant solution with one or more oxidants; e) separating the target metal-pregnant solution from the one or more precipitated non-target metals; and f) recovering the at least one target metal from the target metal-pregnant solution.

In one example, the method of recovering one or more target metals from a feedstock comprises: a) providing a feedstock, said feedstock comprising at least one target metal and one or more non-target metals; b) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises: i) ammonia; and ii) one or more ammonium salts; and ill) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and e) separating the target metal-pregnant solution from the one or more precipitated non-target metals; and f) recovering the at least one target metal from the target metal-pregnant solution.

In one example, the method of recovering one or more target metals from a feedstock comprises: a) providing a feedstock, said feedstock comprising at least one target metal and one or more non-target metals; b) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises:

I) ammonia; and ii) one or more ammonium salts; and iii) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) contacting the target metal-pregnant solution with one or more oxidants; e) maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and f) separating the target metal-pregnant solution from the one or more precipitated non-target metals; and g) recovering the at least one target metal from the target metal-pregnant solution.

In one example, the method of recovering one or more target metals from a feedstock comprises: a) providing a feedstock, said feedstock comprising at least one target metal and one or more non-target metals; b) contacting the feedstock with a first leach solution in the presence of one or more metallic metal reductants in a reductive leach step, wherein the first leach solution comprises:

I) ammonia; and

II) one or more ammonium salts; and iii) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) optionally contacting the target metal-pregnant solution with one or more oxidants and/or maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and e) separating the target metal-pregnant solution from the one or more precipitated non-target metals; and f) recovering the at least one target metal from the target metal-pregnant solution.

In another aspect, the invention relates to a method of recovering one or more target metals from a feedstock, the method comprising: a) providing a feedstock, said feedstock comprising at least one target metal and one or more non-target metals, wherein: i) the at least one target metal is selected from the group consisting of lithium, nickel, and cobalt; and/or ii) the one or more non-target metals are selected from the group consisting of aluminium, copper, iron, and manganese; and/or iii) both I) and ii) above; b) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises: i) ammonia; and ii) one or more ammonium salts; and iii) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) separating the solution from the one or more precipitated non-target metals; and e) recovering the at least one target metal from the target metal-pregnant solution.

In one example, the method of recovering one or more target metals from a feedstock comprises: a) providing a feedstock, said feedstock comprising at least one target metal and one or more non-target metals, wherein: i) the at least one target metal is selected from the group consisting of lithium, nickel, and cobalt; and/or ii) the one or more non-target metals are selected from the group consisting of aluminium, copper, iron, and manganese; and/or iii) both I) and ii) above; b) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises:

I) ammonia; and ii) one or more ammonium salts; and iii) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) contacting the target metal-pregnant solution with one or more oxidants; e) separating the solution from the one or more precipitated non-target metals; and f) recovering the at least one target metal from the target metal-pregnant solution.

I) ammonia; and ii) one or more ammonium salts; and iii) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and e) separating the solution from the one or more precipitated non-target metals; and f) recovering the at least one target metal from the target metal-pregnant solution.

In one example, the method of recovering one or more target metals from a feedstock comprises: a) providing a feedstock, said feedstock comprising at least one target metal and one or more non-target metals, wherein:

I) the at least one target metal is selected from the group consisting of lithium, nickel, and cobalt; and/or

II) the one or more non-target metals are selected from the group consisting of aluminium, copper, iron, and manganese; and/or ill) both i) and II) above; b) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises: i) ammonia; and ii) one or more ammonium salts; and ill) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) contacting the target metal-pregnant solution with one or more oxidants; e) maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and f) separating the solution from the one or more precipitated non-target metals; and g) recovering the at least one target metal from the target metal-pregnant solution.

II) the one or more non-target metals are selected from the group consisting of aluminium, copper, iron, and manganese; and/or ill) both i) and II) above; b) contacting the feedstock with a first leach solution in the presence of one or more metallic metal reductants in a reductive leach step, wherein the first leach solution comprises: i) ammonia; and ii) one or more ammonium salts; and ill) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) optionally contacting the target metal-pregnant solution with one or more oxidants and/or maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and e) separating the solution from the one or more precipitated non-target metals; and f) recovering the at least one target metal from the target metal-pregnant solution.

In another aspect, the invention relates to a method of recovering one or more target metals from a solution, wherein the solution comprises dissolved metal ions of at least one target metal, the method comprising: a) providing a solution comprising dissolved metal ions of at least one target metal, wherein one of the at least one target metals is lithium, and the solution has been prepared in a method comprising: i) contacting a feedstock comprising or consisting of black mass, said black mass comprising lithium and optionally one or more other target metals, and one or more non-target metals; ii) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises:

(a) ammonia; and

(b) one or more ammonium salts; and

(c) optionally one or more additional reductants; iii) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metalpregnant solution; b) separating the solution from the one or more precipitated non-target metals; and c) recovering the at least one target metal from the target metal-pregnant solution.

In one example, the method of recovering one or more target metals from a solution wherein the solution comprises dissolved metal ions of at least one target metal comprises: a) providing a solution comprising dissolved metal ions of at least one target metal, wherein one of the at least one target metals is lithium, and the solution has been prepared in a method comprising: i) contacting a feedstock comprising or consisting of black mass, said black mass comprising lithium and optionally one or more other target metals, and one or more non-target metals; ii) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises:

(a) ammonia; and

(b) one or more ammonium salts; and

(c) optionally one or more additional reductants; iii) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metalpregnant solution; b) contacting the target metal-pregnant solution with one or more oxidants; c) separating the solution from the one or more precipitated non-target metals; and d) recovering the at least one target metal from the target metal-pregnant solution. In one example, the method of recovering one or more target metals from a solution wherein the solution comprises dissolved metal ions of at least one target metal comprises: a) providing a solution comprising dissolved metal ions of at least one target metal, wherein one of the at least one target metals is lithium, and the solution has been prepared in a method comprising: i) contacting a feedstock comprising or consisting of black mass, said black mass comprising lithium and optionally one or more other target metals, and one or more non-target metals; ii) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises:

(a) ammonia; and

(b) one or more ammonium salts; and

(c) optionally one or more additional reductants; iii) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metalpregnant solution; b) maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and c) separating the solution from the one or more precipitated non-target metals; and d) recovering the at least one target metal from the target metal-pregnant solution.

(a) ammonia; and

(b) one or more ammonium salts; and

(c) optionally one or more additional reductants; iii) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metalpregnant solution; b) contacting the target metal-pregnant solution with one or more oxidants; c) maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and d) separating the solution from the one or more precipitated non-target metals; and e) recovering the at least one target metal from the target metal-pregnant solution.

In one example, the method of recovering one or more target metals from a solution wherein the solution comprises dissolved metal ions of at least one target metal comprises: a) providing a solution comprising dissolved metal ions of at least one target metal, wherein one of the at least one target metals is lithium, and the solution has been prepared in a method comprising: i) contacting a feedstock comprising or consisting of black mass, said black mass comprising lithium and optionally one or more other target metals, and one or more non-target metals; ii) contacting the feedstock with a first leach solution in the presence of one or more metallic metal reductants in a reductive leach step, wherein the first leach solution comprises:

(a) ammonia; and

(b) one or more ammonium salts; and

(c) optionally one or more additional reductants; ill) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metalpregnant solution; b) optionally contacting the target metal-pregnant solution with one or more oxidants and/or maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and c) separating the solution from the one or more precipitated non-target metals; and d) recovering the at least one target metal from the target metal-pregnant solution.

In one example, the conditions in the reductive leach step suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution are not suitable for the dissolution of copper present in the feedstock.

In one example, the reductive leach step does not dissolve copper present in the feedstock.

In one example, contacting the target metal-pregnant solution with one or more oxidants comprises exposing the target metal-pregnant solution to an oxidising condition(s).

In one example, contacting the target metal-pregnant solution with one or more oxidants comprises aerial oxidation, for example by air or oxygen sparging, exposure of the solution to high partial pressure of oxygen, or extended exposure to oxygen, including oxygen present in air.

In one example, contacting the target metal-pregnant solution with one or more oxidants comprises addition of one or more oxidants, such as hydrogen peroxide.

In one example, maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals comprises maintaining the targett metal-pregnant solution under oxidising conditions, such as in the presence of an oxidant, for at least about 30 minutes.

In one example, for example when the target metal is Nickel, recovering the at least one target metal from the target metal-pregnant solution comprises at least one of: a) addition of a pH raising agent; or b) addition of a Nickel precipitating agent; or c) solvent extraction; or d) removal of ammonia; or e) any combination of any two or more of a) to d) above. In one example, the pH raising agent is a hydroxide salt. In one example, the hydroxide salt is

LiOH.

In one example, the Nickel precipitating agent is dimethylglyoxime (C4H8N2O2).

In one example, solvent extraction comprises extraction with, for example, Acorga M5640 or equivalents thereof.

In one example, removal of ammonia comprises removal of sufficient ammonia so as to elicit a pH change to approximately 8 and/or to elicit precipitation of Nickel as Nickel hydroxide.

In one example, removal of ammonia comprises removal of ammonia by evaporation, for example evaporation by thermal means or under reduced pressure or a combination thereof.

In one example, at least some of the ammonia removed, for example, by evaporation, is recovered. In one example, at least some of the ammonia removed is recovered for reuse, for example, for use in a subsequent reductant leach step.

In one example, substantially all of the ammonia removed at any step of the method is recovered, for example for reuse.

In one example, for example when the target metal is Cobalt, recovering the at least one target metal from the target metal-pregnant solution comprises at least one of: a) addition of a reducing agent; or b) heating, for example to at least about 80 °C; or c) electrolysis; or d) thermally induced base hydrolysis; or e) any combination of any two or more of a) to d) above.

In one example, recovery of Cobalt comprising the addition of a reducing agent comprises addition of sodium bisulfite or hydrogen gas.

In one example, recovery of Cobalt comprising heating in the presence of a reducing agent comprises heating in the presence of a hydrazine reducing agent, such as hydrazine hydrate. In one example, heating in the presence of a reducing agent comprises heating to reduce coba It(III) ions (Co³⁺) to cobalt(II) ions (Co²⁺) or metallic cobalt (Co⁰) and/or to precipitate cobalt as cobalt hydroxide (CO(OH)2) or as cobalt metal.

In one example, recovery of Cobalt comprising thermally induced base hydrolysis comprises heating to a high temperature (e.g., 80-200°C) in the presence of a strong base. In one example, thermally induced base hydrolysis comprises the addition of a strong base and heating to a high temperature (e.g., 80-200°C). In one example, thermally induced base hydrolysis comprises heating to a temperature of from about 80 °C to about 200 °C in the presence of sodium hydroxide (NaOH) or potassium hydroxide (KOH).

In one example, for example when the target metal is Lithium, recovering the at least one target metal from the target metal-pregnant solution comprises addition of a pH raising agent together with a carbonate salt, optionally together with one or more of: a) evaporation of the target metal-pregnant solution; or b) membrane-based concentration; or c) each of a) and b) above.

In one example, recovery of lithium comprising the addition of a pH raising agent comprises addition of a hydroxide salt, such as CaOH. In one example, recovery of lithium comprising the addition of a pH raising agent comprises addition of a carbonate salt. In one example, recovery of lithium comprising the addition of a pH raising agent and a carbonate salt comprises addition of sodium carbonate.

In one example, recovery of lithium comprising membrane-based concentration comprises reverse osmosis.

In one example, recovery of the at least one target metal from the target metal-pregnant solution comprises at least one of: a) addition of a pH raising agent; or b) addition of a Nickel precipitating agent; or c) solvent extraction; or d) removal of ammonia; or e) any combination of any two or more of a) to d) above; followed by at least one of: f) addition of a reducing agent; or g) heating, for example to at least about 80 °C; or h) electrolysis; or i) thermally induced base hydrolysis; or j) any combination of any two or more of f) to i) above; followed by addition of a pH raising agent together with a carbonate salt optionally together with one or more of: k) evaporation of the target metal-pregnant solution; or l) membrane-based concentration; or m) each of k) and I) above.

In one example, wherein when the feedstock is black mass, recovery of the at least one target metal from the target metal-pregnant solution comprises at least one of: a) addition of a pH raising agent; or b) addition of a Nickel precipitating agent; or c) solvent extraction; or d) removal of ammonia; or e) any combination of any two or more of a) to d) above; followed by at least one of: f) addition of a reducing agent; or g) heating, for example to at least about 80 °C; or h) electrolysis; or i) thermally induced base hydrolysis; or j) any combination of any two or more of f) to i) above.

In one example, wherein when the feedstock is black mass, recovery of the at least one target metal from the target metal-pregnant solution comprises at least one of: a) addition of a pH raising agent; or b) addition of a Nickel precipitating agent; or c) solvent extraction; or d) removal of ammonia; or e) any combination of any two or more of a) to d) above; followed by addition of a pH raising agent together with a carbonate salt optionally together with one or more of: f) evaporation of the target metal-pregnant solution; or g) membrane-based concentration; or h) each of f) and g) above.

In one example, wherein when the feedstock is black mass, recovery of the at least one target metal from the target metal-pregnant solution comprises at least one of: a) addition of a reducing agent; or b) heating, for example to at least about 80 °C; or c) electrolysis; or d) thermally induced base hydrolysis; or e) any combination of any two or more of a) to d) above; followed by addition of a pH raising agent together with a carbonate salt optionally together with one or more of: f) evaporation of the target metal-pregnant solution; or g) membrane-based concentration; or h) each of f) and g) above.

In one example, wherein when the feedstock is black mass such as black mass comprising lithium, nickel, and cobalt, recovery of the at least one target metal from the target metal-pregnant solution comprises at least one of: a) addition of a pH raising agent; or b) addition of a Nickel precipitating agent; or c) solvent extraction; or d) removal of ammonia; or e) any combination of any two or more of a) to d) above; followed by at least one of: f) addition of a reducing agent; or g) heating, for example to at least about 80 °C; or h) electrolysis; or i) thermally induced base hydrolysis; or j) any combination of any two or more of f) to i) above; followed by addition of a pH raising agent together with a carbonate salt optionally together with one or more of: k) evaporation of the target metal-pregnant solution; or l) membrane-based concentration; or m) each of k) and I) above.

In one example, at least some of the solid feedstock residue present in or formed during the reductive leach step is removed after formation of the target meta I -pregnant solution. In one example, at least some of the solid feedstock residue present in or formed during the reductive leach step is removed after formation of the target metal-pregnant solution and before an oxidation step and/or the precipitation of the one or more non-target metal(s).

In one example, including for example when the feedstock is black mass and when the method comprises contacting the target metal-pregnant solution with one or more oxidants and/or maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals, the method comprises removing at least some of the solid black mass residue from the target metal pregnant solution prior to contacting the target metalpregnant solution with one or more oxidants and/or maintaining the target meta I -pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals.

For example, the method comprises: a) providing a feedstock comprising black mass, said black mass comprising at least one target metal and one or more non-target metals; b) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises: i) ammonia; and ii) one or more ammonium salts; and ill) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) removing at least some of the solid black mass residue from the target metal-pregnant solution; e) contacting the target metal-pregnant solution with one or more oxidants; f) maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and g) separating the target metal-pregnant solution from the one or more precipitated non-target metals; and h) recovering the at least one target metal from the target metal-pregnant solution.

In one example, substantially all of the solid feedstock residue, such as substantially all of the solid black mass residue, is removed.

Any of the examples described herein can relate to any of the aspects presented herein.

In one example, the target metal is selected from the group consisting of lithium, nickel, and cobalt.

In one example, the target metal is lithium.

In one example, the feedstock material is selected from the group consisting of e-waste, one or more lithium ion batteries or a derivative or waste stream therefrom such as black mass, and a combination of any two or more thereof.

In one example, the feedstock material is black mass.

In one example, the feedstock comprises one or more non-target metals. In one example, the feedstock comprises one or more non-target metals selected from the group consisting of aluminium, copper, iron, manganese, and zinc.

In one example, the feedstock is black mass comprising copper. In one example, the black mass comprises at least about 2% w/w copper.

In one example, the feedstock is black mass comprising aluminium. In one example, the black mass comprises at least about 2% w/w aluminium.

In one example, the one or more ammonium salts is selected from the group consisting of ammonium chloride, ammonium sulphate, ammonium carbonate, and ammonium acetate. In one example, the one or more reductants is a metal.

In one example, the one or more reductants is a non-target metal.

In one example, the one or more reductants is a metal selected from the group consisting of iron, aluminium, manganese, copper, or zinc.

In one example, the one or more reductants is a target metal selected from nickel or cobalt.

In one example, the one or more reductants is a metal in its metallic (M(0)) oxidation state, wherein said metal is the same element as a metal or metal ion already present in the feedstock.

In one example, the one or more reductants is a metal in its metallic (M(0)) oxidation state, wherein said metal when in an oxidised state is not soluble in a basic ammonia solution.

In one example, the one or more reductants is a metal in its metallic (M(0)) oxidation state, wherein said metal when in an oxidised state is not soluble in a basic ammonia solution and is present as a metal or metal ion in the feedstock.

In one example, the one or more reductants is a metal in its metallic (M(0)) oxidation state, and is added to the first leach solution in an amount sufficient to provide a concentration of at least about 1% w/w.

In one example, the one or more reductants is a metal in its metallic (M(0)) oxidation state, and is added to the first leach solution in an amount sufficient to provide a concentration of about 1% w/w to about 20% w/w.

In one example, the one or more reductants is a metal in its metallic (M(0)) oxidation state, and is added to the first leach solution in an amount sufficient to provide a concentration of about 2% w/w to about 20% w/w, of about 2% w/w to about 15% w/w, of about 2% w/w to about 10% w/w, of about 5% w/w to about 20% w/w, of about 5% w/w to about 15% w/w, or about 5% w/w to about 10% w/w.

In one example, the one or more reductants is a metal with a particle size with at least one dimension in a range of 0.01 to 1mm. Such particles may be regularly or irregularly shaped or elongated particles.

In one example, the one or more reductants is a metal with a particle mesh sizes of from about 100 mesh to about 250 mesh.

In one example, the reductant comprises iron filings, iron shavings, or scrap iron.

In one example, the reductant comprises, consists essentially of, or consists of, iron powder.

In some examples, the reductive leach step further comprises addition of one or more additional reductants.

In one example, the one or more additional reductants is a non-metallic reductant.

In one example, one or more of the one or more additional reductants is selected from the group consisting of organic acids, urea, ferrous salts such as ferrous sulfate, activated carbon, organic acids, hydrazines, hydrides, borohydrides, inorganic acids, or combinations of any one or more thereof.

In one example, the one or more additional reductants is selected from the group consisting of iron (ferrous) sulfate, urea, and hydrazine. In one example, one or more of the one or more additional reductants is selected from the group consisting of ascorbic acid or a salt thereof, citric acid or a salt thereof, formic acid or a salt thereof, lactic acid or a salt thereof, malic acid or a salt thereof, oxalic acid or a salt thereof, tartaric acid or a salt thereof, and uric acid or a salt thereof. In one example, the reductive leach step is at a temperature of between about 20 °C to about 85 °C. For example, the reductive leach step is at a temperature of between about 20 °C to about 80 °C, between about 20 °C to about 75 °C, between about 20 °C to about 70 °C, between about 20 °C to about 65 °C, between about 20 °C to about 60 °C, between about 20 °C to about 55 °C, or between about 20 °C to about 50 °C.

In one example, the reductive leach step is at a temperature of about 50 °C or below.

In one example, the reductive leach step is at or about room temperature.

In one example, the target metal-pregnant solution is an aqueous solution containing more than lOppm of a or the target metal.

In one example, at least about 90% of a or the target metal is recovered. In one example, at least about 90% of each target metal is recovered.

In one example, at least about 95%, or at least about 99%, of a or the target metal is recovered. In one example, at least about 95%, or at least about 99%, of each target metal is recovered.

In one example the maintaining step in which the oxidant is in contact with the target metalpregnant solution or the oxidising conditions are maintained is maintained for between about 0.5 and 48 hours.

In one example, the maintaining step in which the oxidant is in contact with the target metalpregnant solution or the oxidising conditions are maintained is maintained at a temperature of between about 20 °C to about 85 °C. For example, the maintaining step in which the oxidant is in contact with the target metal-pregnant solution or the oxidising conditions are maintained is maintained at a temperature of between about 20 °C to about 80 °C, between about 20 °C to about 75 °C, between about 20 °C to about 70 °C, between about 20 °C to about 65 °C, between about 20 °C to about 60 °C, between about 20 °C to about 55 °C, or between about 20 °C to about 50 °C.

In one example, the maintaining step in which the oxidant is in contact with the target metalpregnant solution or the oxidising conditions are maintained is maintained is maintained for a time and under conditions suitable to form a non-target metal-barren solution - that is, a solution substantially devoid of non-target metal.

In various examples, the methods contemplated herein are carried out at basic pH. For example, the leach step is carried out at basic pH, and when performed the oxidation step is carried out at basic pH, and the non-target metal precipitation step(s) is carried out at basic pH, and the one or more target metal recovery steps are each carried out at basic pH.

In various examples, the methods contemplated herein do not involve a solvent extraction step.

In various examples, the methods contemplated herein do not involve electrowinning.

In one example, the method comprises a non-target material recovery step.

In one example, the method comprises a graphite recovery step.

In one example, the graphite recovery step comprises admixing the material remaining after the leach with an aqueous solution or water.

In one example, the graphite recovery step comprises admixing the material remaining after the separation of the one or more target metals with an aqueous solution or water.

In one example, the graphite recovery step comprises physical separation, for example, physical floatation, such as for example froth floatation reliant on graphite's hydrophobicity compared to one or more other components of the non-target material, such as the one or more non-target metals or non-target metal salts.

In one example, the method is a method substantially as exemplified herein in the Examples.

In one example, after the target metal-pregnant solution has been contacted with one or more oxidants, the method comprises: a) a Nickel recovery step to yield a low-Nickel solution; b) subjecting the low-Nickel solution to a Cobalt recovery step to yield a low-Cobalt solution; c) subjecting the low-Cobalt solution to a Lithium recovery step to yield a Lithium precipitate.

In one example, the Nickel recovery step comprises addition of a pH raising agent, such as a hydroxide salt.

In one example, the Nickel recovery step comprises addition of a pH raising agent sufficient to raise the pH to about 11 or above.

In one example, the Nickel recovery step comprises adding lithium hydroxide.

In one example, the low-Nickel solution comprises a Ni concentration less than about 15% of the Nickel concentration of the target metal-pregnant solution.

In one example, the Cobalt recovery step comprises addition of a reductant.

In one example, the Cobalt recovery step comprises addition of a metallic reductant.

In one example, the Cobalt recovery step comprises addition of metallic Cobalt.

In one example, the low-Cobalt solution comprises a Co concentration less than about <15%% of the Co concentration of the low Ni solution.

In one example, at least some of the ammonia removed is collected, for example for reuse.

In one example, the method comprises: a) subjecting the target metal-pregnant solution to a Nickel recovery step to yield a low- Nickel solution; b) subjecting the low-Nickel solution to a Cobalt recovery step to yield a low-Cobalt solution; c) subjecting the low-Cobalt solution to a Lithium recover step to yield a Lithium precipitate.

In one example, the Cobalt recovery step comprises addition of metallic Cobalt.

In one example, the Cobalt recovery step comprises electrowinning.

In one example, the method comprises: a) subjecting the target metal-pregnant solution to a Nickel recovery step comprising addition of a pH raising agent to yield a low-Nickel solution; b) subjecting the low-Nickel solution to a Cobalt recovery step comprising additionl of metallic Cobalt to yield a low-Cobalt solution; c) subjecting the low-Cobalt solution to a Lithium recovery step to yield a Lithium precipitate. In various examples, the method comprises the preliminary step of pre-processing the feedstock.

In various examples, the method comprises a preliminary pre-processing step, such as

• removal of contaminants and/or non-metallic components, such as binders (e.g. Polyvinylidene Fluoride (PVDF);

• one or more carbothermal reactions to reduce metal oxides and/or oxidise graphite;

• milling, such as ball milling, with Aluminium (Al) powder and/or Iron (Fe) powder to reduce Li metal oxide; while additive is oxidised iii) Separation or removal of PVDF

In various examples, the pre-processing step provides a target metal-containing composition comprising Lithium and Cobalt, and at least one metal selected from the group consisting of Aluminium (Al), Copper (Cu), Manganese (Mn), Nickel (Ni), and Iron (Fe).

In one example, the feedstock is a solid material. In one example, the feedstock is particulate solid feedstock, such as particulate lithium-ion batteries.

In one example, wherein when the feedstock is a solid material, the reductant leach is preceded by one or more pre-processing steps selected from the group consisting of: chip removal; grinding, milling, or comminuting electronic waste, for example to a preselected size; removal of certain density fractions; removal of certain size particles or fractions; removal of one or more magnetic materials; removal of at least a portion of non-target material; and any combination of two or more thereof.

Other aspects, features and advantages of the present invention will become apparent from the following description. It should be understood, however, that the detailed description and the specific examples, while indicating preferred examples of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

The invention is exemplified in the following non limiting examples and with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a flowchart depicting: A - a typical hydro-met method used in BMS refining; B - An example of the process of the invention illustrating its simplicity (low number of steps) and recyclability; and C. a schematic comparison between A. and B.

Figure 2 presents a flowchart depicting one example of the methods contemplated herein, as described in Example 1 herein.

Figure 3 presents a graph depicting the recovery of Cobalt and Nickel in an exemplary method as described herein in Example 10 herein.

Figure 4 presents a flowchart depicting one example of a single stage leach method as contemplated herein.

Figure 5 presents a flowchart depicting one example of a double stage leach method as contemplated herein, as described in Example 1 herein.

Figure 6 presents a flowchart depicting one example of a method as contemplated herein, as described in Example 1 herein.

Figure 7 presents a flowchart depicting one example of a method as contemplated herein. Figure 8 presents a flowchart depicting one example of a single stage leach method as contemplated herein, as described in Example 16 herein.

DETAILED DESCRIPTION

The present invention relates to methods for the recovery of lithium, optionally together with one or more other target metals, from waste such as waste lithium-ion batteries (LIB) and waste streams derived therefrom, such as black mass.

In order to overcome the downsides of current hydrometallurgical approaches, the inventors have devised an alternative method based on the selective extraction of only lithium, cobalt, and nickel from black mass (BMS) in a single process stream (see Figure IB). These three metals account for >98% of the metallic value in black mass. The method operates at the theoretical minimum number of processing steps, greatly simplifying the process. By not having to incorporate aluminium, copper, iron, and manganese removal steps the method is simpler, faster, and cheaper (see Figure 1C) whilst not significantly sacrificing the value created or total mass of material recycled (undesirable metals are in low, but meaningful, concentrations). The operating costs of removing the low value aluminium, copper, iron and manganese are avoided (which have net negative returns based on commodity prices for these elements) and negative environmental impact of recovery of these metals relative to other sources (due to low volumes in waste) is also avoided.

Advantageously, and in contrast to existing acid-based solutions, the methods disclosed herein produce a very low quantity of by-products, all of which can be repurposed in the construction industry, instead of producing hazardous chemical waste. The methods disclosed herein furthermore enable the recycling of the chemical reagents used, allowing each batch of chemicals to be reused multiple times for new feedstock, thereby reducing OPEX and associated carbon emissions.

The selectivity enabled by the methods disclosed herein is due at least in part to performing the leach in a basic solution rather than acidic sulfuric acid. The addition of a reducing agent with a metastable solubility in this solution allows for a 'traceless' reductant to be used so, after valuable metal recovery, the solution can be directly reused saving on water use and preventing any bulk salt outputs. As the leaching step and each of the metal recovery steps are performed in basic conditions, there is no need to neutralise the solution to recover lithium, both eliminating salt output and meaning the majority of the solution can be recycled (<600L wastewater/tonne BMS).

The methods contemplated here do not produce significant amounts of wastewater or salt byproducts.

The methods disclosed herein thus overcome one or more of the downsides of other hydrometallurgical approaches for metal recovery from black mass.

In certain examples, in addition to the valuable target metals, the methods contemplated herein can also recover battery-grade graphite in a single additional step.

The methods described herein recognise that in certain lithium waste streams such as black mass from lithium batteries, certain of the metals present, notably aluminium, iron, and manganese, do not currently contribute to the value of black mass. Notably, unlike the desirable target metals present in black mass, in particular the target metals lithium, cobalt, and nickel, these non-target metals (e.g., aluminium, iron, and manganese) are not soluble in ammonia - see Table 1 below. Table 1. Solubility of metals contained in BMS in ammonia solutions.

Leaching in ammonia solution therefore substantially simplifies further metal recovery procedures, by both (a) limiting the potential number of metals in solution (four of the seven metals present) and (b) ensuring the solution is already in the appropriate pH range for recovery of the most valuable target metal - lithium.

Advantageously, the methods disclosed herein de-risk the processing of waste material, as contamination of the black mass feedstock with non-LIB material (e.g., nickel-cadmium batteries) does not affect processing.

Selected definitions

It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7). These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

Those skilled in the art will appreciate the meaning of various terms of degree used herein. For example, as used herein in the context of referring to an amount (e.g., "about 9%"), the term "about" represents an amount close to and including the stated amount that still performs a desired function or achieves a desired result, e.g. "about 9%" can include 9% and amounts close to 9% that still perform a desired function or achieve a desired result. For example, the term "about" can refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, or within less than 0.01% of the stated amount. It is also intended that where the term "about" is used, for example with reference to a figure, concentration, amount, integer or value, the exact figure, concentration, amount, integer or value is also specifically contemplated.

The term "and/or" can mean "and" or "or".

The term "comprising" as used in this specification means "consisting at least in part of". When interpreting each statement in this specification that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises", and the terms "including", "include" and "includes" are to be interpreted in the same manner.

The term "consisting essentially of" when used in this specification refers to the features stated and allows for the presence of other features that do not materially alter the basic characteristics of the features specified.

The term "consisting of" as used herein means the specified materials or steps of the claimed invention, excluding any element, step, or ingredient not specified in the claim.

The term "contacting" refers to the bringing together, frequently by the mixing of and/or interaction between, two or more entities, such as two or more solutions or substances. One example of this is the contact between a target metal-pregnant solution and a support material. A further example of this is the contact between a lixiviant and a solid feedstock material.

The terms "leachate" or "leach solution" when used herein refers to an aqueous solution in which one or more metals, such as one or more target metal(s), are dissolved. In certain examples of the methods contemplated herein, a leachate or leach solution is formed by addition of a solution to a feedstock. In certain examples, a leachate or leach solution will be a target metal-pregnant solution comprising one or more target metals or target metal ions.

The term "ligand" as used herein refers to a moiety, molecule, compound or macromolecule capable of binding to a target. In the context of this disclosure, the term ligand will typically mean a moiety, molecule, compound or macromolecule capable of binding to a target metal, for example to form a target metal complex, such as a target metal complex suitable for binding.

The term "ppm" refers to parts per million and relates to the concentration of an entity (such as a metal or metal ion, a compound, moiety, support material, or the like) in comparison to another entity - that is, the weight:weight ratio of the respective entities. In specific examples contemplated herein, ppm is used in reference to a target or non-target metal in comparison to a solution in which it occurs.

The term "barren solution" refers to an aqueous solution containing a depleted amount of dissolved metal, for example a depleted amount compared to the feedstock, to the first leach solution, or to a pregnant solution. It is recognised that in extreme cases the referred-to metal(s) or class of metals (e.g., target or non-target metal(s)) may be completely absent in the barren solution.

The term "pregnant solution" refers to a solution, such as an aqueous solution, containing one or more species of dissolved metal. For example, a target metal-pregnant solution contains dissolved target metal(s). In some instances a target metal-pregnant solution also contains at least some undissolved target metal(s) and/or non-target metal(s).

The terms "reducing agent" and "reductant" and grammatical equivalents thereof refer to an agent or combination of agents capable of reducing a target species, for example, capable of reducing a species of metal ion to elemental metal.

The terms "selectivity", "selectively", and grammatical equivalents when used in reference to an agent, such as a solution, a leachate, a reducing agent or reductant, refers to the ability of the agent to preferentially interact, such as to interact with a specified metal ion or species thereof. For example, when used in reference to a reductant, selectivity or selectively refers to the ability of the reductant to favourably reduce the one or more specified metal ion species over one or more other metal ion species present (for example one or more non-target metal ion species in a sample and/or solution).

The term "metal" includes both elemental metal and ions of a metal.

The term "target metal" includes both elemental metal and ions of a target metal or a plurality of metals, and is used herein in reference to a metal that is, in the context of this disclosure, desired, for example, a metal the recovery of which is desirable. It is recognised that a particular target metal may exist in different ionic states (including elemental form) or a plurality of ionic states in different steps of the methods or parts of the systems disclosed herein. In specifically contemplated examples, the target metal is dissolved or partially dissolved in the solutions employed herein, either as an ion (or ions), a salt or salts, a complex, or in an elemental form, or a combination thereof. Similarly, the target metal may exist in solid form either as an ion (or ions), a salt or salts, a complex, or in an elemental form, or a combination thereof as the context dictates.

The term "non-target metal" refers to metal(s) in similar states of matter as per the term "target metal" above, but that in the context of this disclosure are not desired metals and/or the recovery of which is not desired. A non-exhaustive list of examples of non-target metals in the context of this disclosure includes copper, tin, aluminium, lead, iron, and zinc.

The term "non-target metal-barren solution" refers to a solution, including an aqueous solution, containing a depleted amount of dissolved non-target metal, for example depleted compared to the feedstock, to the first leach solution, or to a pregnant solution. It is recognised that in specifically contemplated examples, one or more non-target metal(s) is substantially or completely absent from the non-target metal-barren solution.

In one example the target metal-pregnant solution contains at least about 500ppm target metal. In one example the target metal-pregnant solution contains at least about lOOOppm target metal, for example, at least about 1500ppm, or at least about 2000ppm target metal.

In one example the target metal-pregnant solution contains at least about 500ppm lithium, for example, at least about lOOOppm lithium, at least about 1500ppm lithium, or at least about 2000ppm lithium.

In one example the target metal-pregnant solution contains between about lOOppm to about 2000ppm, or between about lOOppm to about lOOOppm, or between about lOOppm to about 500ppm, or between about lOOppm to about 200ppm, or about lOOppm of the target metal.

In one example, the target metal-pregnant solution contains less than about lOOppm non- target metal(s).

In one example, immediately prior to the separation of the target metal-pregnant solution from the one or more precipitated non-target metals, the target metal-pregnant solution contains less than about lOOppm non-target metal(s).

In one example the target metal-pregnant solution contains between about O.lppm to about lOOppm, or between about 0.5ppm to lOOppm, or between about 0.5ppm to 50ppm, or between about 0.5ppm to 20ppm, or between about 0.5ppm to lOppm, or between about 0.5ppm to 5ppm, or between about 0.5ppm to 2ppm of non-target metal(s).

In one example the target metal-pregnant solution contains between about lppm to lOOppm, or between about lppm to 90ppm, or between about lppm to 80ppm, or between about lppm to 70ppm, or between about lppm to 60ppm, or between about lppm to 50ppm, or between about lppm to 40ppm, or between about lppm to 30ppm, or between about lppm to 20ppm, or between about lppm to lOppm of the non-target metal(s).

In one example, immediately prior to the separation of the target metal-pregnant solution from the one or more precipitated non-target metals, the target metal-pregnant solution contains between about lppm to lOOppm, or between about lppm to 90ppm, or between about lppm to 80ppm, or between about lppm to 70ppm, or between about lppm to 60ppm, or between about lppm to 50ppm, or between about lppm to 40ppm, or between about lppm to 30ppm, or between about lppm to 20ppm, or between about lppm to lOppm of the non-target metal(s).

In one example the target metal-pregnant solution contains at least 10-fold more target metal than non-target metal. In one example the target metal-pregnant solution contains at least 20-fold, or at least 30-fold, or at least 40-fold, or at least 50-fold, or at least 60-fold, or at least 70-fold, or at least 80-fold, or at least 90-fold, or at leaset 100-fold more target metal than non-target metal. In one example, the target meta I -pregnant solution contains more than 100-fold more target metal than non-target metal.

In one example the target metal-pregnant solution contains at least 150-fold more target metal than non-target metal. In one example the target metal-pregnant solution contains at least 200-fold, or at least 300-fold, or at least 400-fold, or at least 500-fold, or at least 600-fold, or at least 700-fold, or at least 800-fold, or at least 900-fold, or at least 1000-fold more target metal than non-target metal. In one example, the target metal-pregnant solution contains more than 1000-fold more target metal than non-target metal.

In certain examples, the target meta I -pregnant solution contains at least about 1500-fold more target metal than non-target metal. In certain examples, the target meta I -pregnant solution contains at least about 2000-fold more target metal than non-target metal.

In certain examples, the target metal-pregnant solution contains from about 500-fold to about 2000-fold more target metal than non-target metal.

In one example the non-target metal-barren solution contains less than O.lppm, or less than lppm, or less than 2ppm, or less than 5ppm, or less than lOppm, or less than 20ppm, or less than 50ppm, or less than lOOppm of the non-target metal. In one example the non-target metal-barren solution contains between about 0.001 and lOOppm, or between about 0.001 and 50ppm, or between about 0.001 and 50ppm, or between about 0.01 and 50ppm of the non-target metal(s).

As described herein, in one aspect, the invention relates to a method of recovering one or more target metal(s) from a feedstock (including a waste material such as black mass), the method comprising subjecting the feedstock to an ammonia/ammonium salt leach in the presence of a metallic reductant, such as metallic iron, metallic copper, or metallic aluminium, followed by oxidation of the solution.

In another aspect, the invention relates to a method of recovering one or more target metals from a feedstock, the method comprising: a) providing a feedstock, said feedstock comprising at least one target metal and one or more non-target metals; b) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises:

I) ammonia; and

II) one or more ammonium salts; and ill) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) separating the target metal-pregnant solution from the one or more precipitated non-target metals; and e) recovering the at least one target metal from the target metal-pregnant solution.

In certain particularly contemplated examples, the one or more reductants is metallic iron. Notably, the use of iron as a reductant for the first leaching step provides three important benefits. It is suitable for the reduction of cobalt(III) in the cathode to cobalt(II) thereby allowing extraction, while also limiting buildup of copper in solution through a displacement reaction, and it removes itself from solution and further process requirements. In addition, iron is a very economical metallic reductant - even scrap iron filings can be used.

The methods disclosed herein utilise an ammonia solution in combination with a metallic reductant, which due to its solubility in ammonia solutions does not build up in the solution. As no soluble by-products are left in solution, the leaching solution can be reused repeatedly with no adverse effects. The applicant believes it is the first to achieve such simple recyclability.

In the trimetallic leach solution created in at least some of the methods disclosed herein, the three dominant species are Li⁺, [N i (N H₃)₆]²⁺, and [Co(NH₃)₆]³⁺. Notably, all three species have very different chemical properties arising from their nature (alkali earth metal) and oxidation state (divalent and trivalent transition metals for nickel and cobalt, respectively). These different properties, which are not present in acid solutions (in which the dominant species are mostly divalent: Al³⁺, Co²⁺, Cu²⁺, Fe²⁺, Li⁺, Mn²⁺, Ni²⁺), greatly facilitate their separation.

It has been reported that nickel and cobalt derived from ore can be separated from ammonia solutions using various processes, the most well-known being the commercial Sherrit process used for laterite ores. This involves oxidative sulfuric acid leaching of ore to convert sulfide to sulfate, followed by basification with ammonia to selectively solubilise copper, cobalt and nickel from an appropriate feedstock. High pressure reduction by hydrogen gas is then used to precipitate cobalt metal as a fine power (kinetically favourable), followed by nickel (thermodynamically favourable). The Caron process is also used for nickel and cobalt containing laterite ores, which are first treated by a reductive roast (>650 °C) with added fuel/coal followed by an ammoniacal extraction. Nickel is first removed by solvent extraction with selectivity enforced by the high lability of nickel over cobalt in ammoniacal solution. After nickel removal, cobalt can either be recovered by direct electrolysis to the metallic state, or partially reduced to Co(II) by electrolysis or comproportionation with cobalt shot followed by solvent extraction or precipitation.

Another process for the recovery of nickel and cobalt from ammoniacal solutions involves the precipitation of the triple salt NH₄[Co(NH₃)₆] [Ni(NH₃)₆] (SO4)₃.6H₂O by careful control of the nickel:cobalt:ammonia:sulfate ratio. This is beneficial for ores with a high nickel concentration (e.g. 20: 1 Ni:Co) which due to the required 1: 1 Ni:Co stoichiometry, effectively creates a cobalt-free solution in addition to the mixed cobalt-nickel solid. This triple salt is then re-pulped with water to selectively dissolve the nickel hexaammine leaving hexaamminecoablt(III) sulfate as a crystalline solid. However, due to the Ni:Co requirements this is generally unsuitable for recovery of these metals from lithium ion battery waste.

In examples of the methods disclosed herein, the residual graphite can be separated from the material remaining after the leach by physical froth floatation which relies on graphite's hydrophobicity compared to contaminating metal salts. After purification, the recovered graphite can be used in any relevant industry. Indeed, graphite produced in methods herein disclosed has been validated in new battery cells at the University of New South Wales, Sydney Australia and shows sufficient performance.

Advantageously, in the methods disclosed herein the metals may be leached at low temperature (<50 °C). Although glass can be used, for example at pilot scale, the low temperatures employed will allow plastic tanks and plant to be used at increased scale, leading to a substantial CAPEX saving over more costly materials and plant. A representative example of the recovery of the target metals from the trimetallic leach solution proceeds as follows. As the only labile transition metal, nickel is selectively removed from solution by direct precipitation using a ligand (for example one chosen from DMG, salycilaldoxime, 2- hydroxyacetophenoxime, or 8-hydroxyquinlone). This is highly selective for nickel and proceeds in an exceptionally high yield. The precipitated nickel complex is simply filtered from solution and is then transformed into a precursor for battery manufacture by re-pulping this solid in a small quantity of sulfuric acid which dissolves the nickel as its sulfate salt and precipitates the ligand which can be collected for re-use. The nickel is then crystallised in sufficient purity for battery applications.

Subsequently, the post-nickel removal leach solution only contains the monovalent lithium, and trivalent cobalt. The cobalt may be recovered in its metallic state though direct electrolysis (it is only redox active species in solution) to form pure cobalt metal. If required this can be converted to the desirable sulfate salt. At this stage the solution can be directly re-used to leach more BMS. No drop in leach efficiency is observed when re-used (and appropriately regenerated by ammonia top-up). A volume (nominally set to 30% in some examples) may be diverted into a lithium recovery circuit where it is recovered first as a phosphate salt, then further refined into commodity grade lithium carbonate.

One example of the invention for BMS refining is described in Example 1 and Figure 2 specifying exemplary parameters for one or more leaches, oxidation by contacting with an oxidant, Ni-recovery, Co-recovery and Li-recovery.

In a further example, Figure 4 shows a method of the invention in which a single stage leach is used for BMS refining. In a further example, Figure 5 shows a method of the invention in which a double stage leach is used for BMS refining.

In a further example, Figure 6 shows a method of the invention in which Nickel is recovered by DMG addition, cobalt recovery by electrowinning and lithium carbonate recovery by addition of sodium carbonate.

In a further example, Figure 7 shows a method of the invention in which Nickel is recovered by lithium hydroxide addition, cobalt recovery by reduction of hexaamminecobalt(III) with Co(0), and lithium carbonate recovery by addition of sodium carbonate.

In a further example, Figure 8 shows a method of the invention in which co-recovery of Nickel and Cobalt is achieved by combined nickel and cobalt hydroxide precipitation and lithium carbonate/hydroxide is recovered by evaporation.

In various examples, the process comprises a leach step followed by a metal recovery step. In one example, the leach step is performed according to the example shown in Figure 4 or the example shown in Figure 5. In one example, the metal recovery step is performed according to any of the examples shown in Figures 6, 7, or 8. Accordingly, the following process combinations provide specific examples of the invention:

• The leach step of Figure 4, followed by the metal recovery step of Figure 6.

• The leach step of Figure 4, followed by the metal recovery step of Figure 7.

• The leach step of Figure 4, followed by the metal recovery step of Figure 8.

• The leach step of Figure 5, followed by the metal recovery step of Figure 6.

• The leach step of Figure 5, followed by the metal recovery step of Figure 7.

• The leach step of Figure 5, followed by the metal recovery step of Figure 8. Each of these combinations provides a distinct example of the process and variations within each step may be employed without departing from the scope of the invention.

The invention is further described with reference to the following examples. It will be appreciated that the invention as claimed is not intended to be limited in any way by these examples.

EXAMPLES

The following General Procedure was used for leaching valuable metals from black mass with a metallic reductant

General Procedure:

1. A known quantity of black mass and metal powder were mixed with a prepared ammoniaammonium salt leach solution at the specified temperature. Any additional additives were added to this slurry.

2. The reaction was maintained under controlled agitation conditions for the reaction duration.

3. Post-leaching, samples were filtered to separate the leachate from the residual solid.

4. The metal concentrations in the leachate were analysed to determine the efficiency of target metal extraction.

Example 1 - Extraction of target metals from black mass

A pilot case study (2L scale), summarised in Figure 2 and Table 2 below presents an example of the process described herein. This example combines the method shown in Figure 5 with the metal recovery example shown in Figure 6.

Table 2. Extraction and recovery yields of metals from black mass

As shown above, the leaching process can recover >90% of the lithium, cobalt and nickel. The European Commission has set recycling targets of 90% for cobalt and nickel and 50% for lithium by end of 2027 rising to 95% and 80% by 2031. The method exemplified herein already meets or exceeds this target. The strict and effective removal of non-valuable metals enabled by the methods disclosed and exemplified herein limits their inclusion in the target metal outputs, making purity levels of >98% readily achieveable. Purity levels suitable for re-use in battery manufacture can be readily attained by the single additional purification steps disclosed herein, allowing for a circular metal economy.

Representative examples of the methods disclosed herein which employ iron as the additional metallic reductant recognise that iron is meta-stable enough to not dissolve in the leaching solution. Target metal recovery steps from this leach solution do not rely on solvent extraction, but rather direct solidliquid extractions which maintain the simplicity of the methods disclosed herein. The methods described herein allow a low carbon footprint, low cost and economically viable target metal recovery process that is significantly different to other hydrometallurgical processes currently being used or developed. In summary, the highly selective processes described and exemplified herein utilise inexpensive reagents (e.g., scrap iron), a reusable lixiviant (recyclable ammonia), and are capable of operating at moderate temperatures (~50 °C) to provide high yielding recovery of pure critical metals (lithium, cobalt and nickel) and material (graphite). This culminates in a low capital cost, scalable and efficient recycling process.

Example 2 - Analysis of black mass samples

Black mass contains a mixture of LIB electrode materials alongside residual particles of current collectors (metallic copper and aluminium). The cathode material contains a lithiated metal salt, including lithium metal oxide (metal being a combination of nickel, manganese, cobalt or aluminium) or lithium iron phosphate. The anode material is predominantly graphite and constitutes the balance of mass.

Four examples of black mass were analysed. Metal composition was determined by digestion of black mass in 60°C aqua regia and analysis by MP-AES, carbon determined by microanalysis.

Example 3 - Use of different metals as reductants

Different metals can be used as reductants to leach valuable metals from black mass. Without wishing to be bound by any theory, the inventors believe it is favourable if the metallic reductant(s) is selected based on the criteria it/they do not introduce a new solution phase species to the system upon their oxidation. Examples of contemplated metallic reductants for use herein include:

• Iron - oxidized to ferrous hydroxide and ferric oxide in basic conditions, both of which are insoluble species so are not significantly present in solution.

• Manganese - predominantly oxidized to manganese dioxide at high pH. Trace levels may be removed in a subsequent oxidation step.

• Cobalt - oxidized to divalent or trivalent ammine complexes. This metal is present in black mass in a highly oxidized state and does not represent a new metal being added to the system.

• Nickel - oxidized to divalent nickel ammine complex. This metal is present in most black mass systems in a highly oxidized state and does not typically represent a new metal being added to the system.

• Aluminium - oxidized to aluminium hydroxide or alumina which are both insoluble under basic conditions.

• Copper - oxidized to divalent copper ammine complex. This metal is present in most black mass in a metallic state and does not represent a new metal being added to the system. It does however add a fourth metal to solution that needs to be removed.

The general procedure outlined above was followed with the following specifications. Where relevant yields include amount of added metal.

The table below shows leaching black mass with different metal reductants in an ammonia/ammonia chloride system.

Discussion

When additional cobalt or nickel metal powder is added, precipitation of target metal salts was observed to occur during filtration which may artificially lower observed extractive yields. Lithium (which does not precipitate) yield is therefore the best measure of metal effectiveness and iron displays the best reductive properties. With this in mind, iron metal is the preferred metallic reductant. It has the additional benefit of preventing copper dissolution in the leach, limiting a low value metal from leaching and therefore increasing selectivity of the leach. Example 4 - Ammonia Leaching of Target Metals from Black Mass

Different acids can be utilised in conjunction with a metal and ammonia to facilitate the leaching of target metals from black mass.

Materials and Methods

The General Procedure was followed with the following specifications.

In some cases ammonium salts were introduced by dissolution of salts, in other cases by introduction of additional ammonia and an acid.

Results

The leaching efficiency of each acid system for cobalt (Co), nickel (N I), iron (Fe), aluminium (Al), manganese (Mn), lithium (Li), and copper (Cu) was evaluated using iron metal as a reductant. The percentage yields of extracted metals from black mass into solution for each anion system are detailed in the table below:

Discussion

The results indicate that there is only a slight difference in valuable metal extraction yields and selectivity when using different ammonium salts in the presence of iron as a reductant. Generally the yields of cobalt, nickel and lithium are between 40-55%. Copper is co-extracted in the presence of ammonium phosphate and ammonium chloride. Cobalt and lithium yields are suppressed in the presence of phosphoric acid. These findings support the feasibility of ammonia-based leaching strategies for targeted metal recovery in battery recycling applications.

Example 5 - Ammonia leach at varying temperatures

The effect of temperature was evaluated by performing identical experiments at different temperatures.

Materials and methods

The black mass used in this study was composed of Sample 2 as described in Example 1. The leaching solution contained 7.5M ammonia combined with 2M HCI acid. Iron was introduced at a concentration of 0.1M. The solid loading was maintained at 5%. The leaching reaction was carried out for a total duration of 270 minutes.

Three leaches were carried out at different temperatures - room temp, 50°C, and 85°C according to the General Procedure described above.

Results

The yield of valuable cobalt, nickel and lithium increased as the temperature increased. Undesirable manganese and copper leaching increased as the temperature increased from room temperature to 50 °C, but decreased when 85°C was reached. Discussion

The results demonstrate that increasing the reaction temperature increases the extraction of cobalt, nickel and lithium while simultaneously lowering the amount of undesirable co-extracted iron, aluminum, manganese and copper.

Example 6 - Effect of additional reductants Leach yields can be improved by addition of an additional reductant, for example, a co-reductant. Coreductants include reagents capable of reducing lithium metal oxide and do not introduce a new solution phase species.

The leaching efficacy of a control sample (urea only) was compared to the effect of iron powder or combined iron powder and urea on extraction of metals from black mass in ammonium carbonate system. The following parameters were used:

Effect of iron powder, and combined iron power ferrous sulfate and iron powder hydrazine hydrate on extraction of metals from black mass in ammonium sulfate system.

Yields of target metals are increased with additional reductants, but selectivity drops. Example 7 - effect of solid loading 2-20%

The effect of solid loading was evaluated by performing identical experiments at different loadings following the General Procedure. The amount of iron and ferrous sulfate was scaled to the amount of black mass added. Equivalent to 0.1M Fe at 10% loading.

Discussion

Yield remained substantially consistent from 2% to 15% solid loading after which yields dropped in all target metals. Copper remained substantially undissolved in all cases. Stirring with magnetic stirrer became difficult in greater than 10% loading which may contribute to low yields which could be overcome through choice of alternative stirring mechanisms at larger scale (e.g. overhead stirring). The ideal solid loading is therefore 10% or less.

Example 8 - Effect of multiple leaches

Multiple leaches were performed on samples that used slightly different amounts of additional reductant iron sulfate in combination with iron metal.

Discussion

Most of the valuable metals were leached in the first leach. Further value metals were extracted with a subsequent leach. Example 9 - Oxidation of leach solution to enhance target metal selectivity

Standard leach conditions to produce a target metal-pregnant solution as described above are selective for lithium, cobalt and nickel over iron, manganese and copper. However, the inventors have found that some iron and manganese may remain in the solution after the leach. This example describes an additional step of subjecting the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more of the non-target metals. This example describes the introduction of an oxidant to the leach solution. The inventors believe, without wishing to be bound by any theory, that it is preferable to carry out this oxidizing step after the solid black mass residue has been removed from solution, as action of an oxidant will bring copper metal into solution.

The table below shows oxidation by air bubbling from copper/ammonium chloride/ammonia solution leach solution. Note that very little iron and aluminium were present within the leach solution, and were reduced below detection limits. Manganese dropped over 2.5 hours to 1 % of the leached concentration, while target nickel, cobalt and lithium concentrations remained substantially constant. This clearly indicates the selectivity of the process described herein.

The table below shows metal composition in ppm following oxidation by air sparging from iron/iron sulfate leach of black mass.

Discussion

Treatment of the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals achieved selective precipitation of the non-target metals thus facilitating downstream extraction of target metals.

Example 10 - Separation of nickel and cobalt from ammonia/ammonium sulfate solution

To a 60ml target-metal pregnant solution derived from an ammonia/ammonium sulfate leach containing cobalt, nickel and lithium at pH=9.53, lithium hydroxide monohydrate was added in two portions until the pH remained above 11 (4g then an additional 2g). This was sufficient to remove the nickel from solution as nickel hydroxide but did not remove cobalt from solution in significant amounts. Subsequently, when a reductant, in this case cobalt metal, was added to solution, it is believed that the inert trivalent cobalt ammine species were reduced to labile divalent species which undergo ligand exchange and were converted to insoluble hydroxide species, thus removing them from solution. Figure 3 shows nickel and cobalt concentrations following the steps of the recovery process described in this example.

The inventors believe, without wishing to be bound by any theory, that if a reductant, for example iron, was not used, copper would be present in the ammonia solution. Then, if both nickel and copper are present, and the solution pH increased to the levels demonstrated, both nickel and copper hydroxides would precipitate - yielding an impure nickel product. Therefore, and again without wishing to be bound by any theory, the inventors believe that methods using reductants that suppress copper dissolution in the leach stage facilitate the advantageous recovery of high purity nickel and cobalt.

Example 11 - Recovery of Nickel using dimethylglyoxime (DMG)

DMG can be used to recover nickel selectively from a solution containing nickel, cobalt and lithium. Two equivalents of DMG are required to remove nickel.

In this experiment, to a non-target metal free leach solution (previously subject to ammonia/ammonium sulfate/iron leach and then oxidation), was added DMG in a 2: 1 molar ratio to nickel as a solid at 40C. The solution was stirred for 4 hours then filtered and washed with water.

DMG was shown to selectively remove nickel in the presence of cobalt and lithium from the ammonia solution.

Example 12 - DMG used to recover nickel

A target metal pregnant leach solution containing nickel is prepared by leaching BMS using an ammoniacal leach solution. The leaching process is carried out using an iron metal reductant followed by an oxidation step using an oxidising agent such as air or hydrogen peroxide. Ni is recovered from the target metal pregnant leach solution (PLS) containing Ni, Co and Li using a dimethylglyoxime (DMG) precipitation method. DMG is then introduced into the PLS as a powder, slurry in water or solution in ethanol under continuous stirring.

Upon addition of the DMG reagent, a pink Ni-DMG complex precipitates, signifying selective nickel chelation. The reaction is maintained under agitation for approximately 30 minutes to ensure complete precipitation of Ni-DMG. The resulting precipitate is then separated from the solution via vacuum filtration and washed with deionised water to remove residual impurities.

The recovered DMG complex can then be transformed to familiar nickel products by thermal decomposition at >400°C to yield NiO, or subjected to concentrated sulfuric acid followed by crystallization to yield nickel sulfate.

Chemical analysis via microwave-plasma atomic emission spectrometry (MP-AES) showing that the recovered Ni exhibits a purity greater than 99.5%, with minimal contamination from Fe, Cu, Co, Mn, and Mg supports the capability of this process to recover high purity Nickel. This process demonstrates an efficient and selective approach for Ni recovery from an ammonia/ammonium-based leach solution using the DMG method. The inventors believe, without wishing to be bound by any theory, that in circumstances in which a reductant is omitted in the leach step, Cu (at least) would be carried through and contaminate the Ni product.

Example 13 - Recovery of Nickel as Ammonium Nickel Sulfate

After an ammonia/ammonium sulfate leach solution containing lithium, nickel and cobalt has been subjected to an oxidation stage to remove trace non-target metal impurities, nickel can be recovered selectively as the double salt ammonium nickel sulfate by removal of excess ammonia.

In this experiment an ammonia/ammonium sulfate/iron metal leach solution was subjected to oxidation to significantly remove non-target metals. It was then heated to 80°C to reduce the volume to approximately 25% of its initial volume. When crystals began to appear in solution heating was stopped and the solution was cooled to room temperature.

The green crystalline solid, identified by PXRD to be the double salt, was filtered from solution and washed with cold water. More than 70% of the nickel was removed from solution, with no concurrent removal of cobalt or lithium. The final pH of the solution remained above pH 9.

Example 14 - Evaporation Method for Nickel Recovery

A target metal pregnant leach solution containing nickel is prepared by leaching BMS using an ammoniacal leach solution. The leaching process is carried out using an iron metal reductant followed by an oxidation step using an oxidising agent such as air or hydrogen peroxide. The resulting pregnant leach solution (PLS) contains Li and Ni and Co in stabilised ammoniacal complexes.

Nickel is recovered from the PLS using an evaporation method. The PLS is transferred to an evaporation vessel and heated to a temperature between 50-90°C, sufficient to drive off excess ammonia. Reduced pressure may be used to promote selective evaporation of ammonia while concentrating the dissolved metal species. As evaporation proceeds, the ammonia concentration decreases, leading to the precipitation of ammonium nickel sulfate - (NH4)2Ni(SO4)2. The lability of nickel(II) ammine complex versus inertness of coba It(III) ammine complexes in initial solution is predominantly responsible for the selectivity of precipitation. The relative insolubility of the ammonium nickel sulfate salt versus its ammonium cobalt sulfate analogue may also contribute to purity.

The evaporation is controlled to maintain a final pH of approximately 7.5-9.5, optimising Ni precipitation while minimising co-precipitation of other metals. This is particularly efficient for black mass that contains a high proportion of nickel.

The double salt is separated from the solution via vacuum filtration and washed with cold water.

Chemical analysis via microwave-plasma atomic emission spectrometry (MP-AES) showing that the recovered Ni exhibits a purity greater than 99.5%, with minimal contamination from Fe, Cu, Co, Mn, and Mg supports the capability of this process to recover high purity Nickel. This process demonstrates an efficient and selective approach for Ni recovery from an ammonia/ammonium sulfate-based leach solution using the evaporation method. The inventors believe, without wishing to be bound by any theory, that in circumstances in which non-target metals are dissolved in the leach step but not removed in a subsequent step, they may be carried through and contaminate this nickel product.

Example 15 - Electrowinning to recover cobalt

Once non-target metals and nickel have been removed from solution, cobalt may be recovered selectively over lithium by electrowinning.

A stainless steel cathode and lead anode was set up with a fixed current of 0.4 Amp in a solution containing cobalt derived from an ammonia/ammonium sulfate leach. The reaction was continued until the solution turned colourless, which indicated there were no transition metals left in solution.

The cathode was then removed from solution and plated cobalt metal peeled off. The inventors believe, without wishing to be bound by any theory, that if copper had been left in solution it would have plated preferentially to cobalt, and further, had nickel been present it may also have contaminated the cobalt product. Example 16 - Mixed metal hydroxide recovery of Ni and Co

Nickel and cobalt can be recovered together to reduce processing steps as shown in Figure 8. A leach using iron metal was performed as outlined in the table below.

The leach was effective and 95% of the cobalt, 97% of the nickel and 74% of the lithium was brought into solution, but only 14% of the iron and 12% of the manganese. Following the leach the solution was subject to oxidation by bubbling air through the solution at 45°C. After two hours all remaining trace non-target metals iron and manganese were filtered off as their insoluble oxides leaving only nickel, cobalt and lithium in solution. The oxidation solids did not contain any nickel or lithium, but did contain 1% of the cobalt.

The pH of the subsequent solution was then increased to 13 by addition of lithium hydroxide and the solution heated to 85 C. After 4 hours, the volume of the solution had reduced by approximately 20% and become colourless indicating no nickel or cobalt remained dissolved. The mixed metal hydroxide precipitate contained 89% of the cobalt and 94% of the nickel leached from the black mass. 27% of the total lithium (from black mass and lithium hydroxide) remained on the solids as lithium carbonate which was removed from the hydroxides in a polishing step through introduction of CO2 gas providing a sufficiently pure Co/Ni mixed hydroxide precipitate.

The remaining lithium solution was combined with the lithium containing CO2 polishing solution, and was further reduced in volume to yield more lithium carbonate precipitate, and a solution of lithium hydroxide which can be re-used as the lithium hydroxide source for nickel and cobalt removal in subsequent processes.

The mass flow table below shows the step-by-step mass and percentage of initial metal transferred to each step of this example of the process for leaching and metal recovery.

The entire disclosures of all applications, patents and publications cited above are herein incorporated by reference in their entirety.

Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

It should be noted that various changes and modifications to the presently preferred examples described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention. The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

Aspects of the invention have been described by way of example only, and it should be appreciated that variations, modifications and additions may be made without departing from the scope of the invention, for example when present the invention as defined in the claims. Furthermore, where known equivalents exist to specific features, such equivalents are incorporated as if specifically referred in this specification.

Claims

1. A method of recovering one or more target metals from a feedstock, the method comprising: a) providing a feedstock, said feedstock comprising at least one target metal and one or more non-target metals; b) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises:

I) ammonia; and ii) one or more ammonium salts; and iii) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) optionally contacting the target metal-pregnant solution with one or more oxidants and/or maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and e) separating the solution from the one or more precipitated non-target metals; and f) recovering the at least one target metal from the target metal-pregnant solution.

2. A method of recovering one or more target metals from a feedstock, the method comprising: a) providing a feedstock, said feedstock comprising at least one target metal and one or more non-target metals, wherein: i) the at least one target metal is selected from the group consisting of lithium, nickel, and cobalt; and/or ii) the one or more non-target metals are selected from the group consisting of aluminium, copper, iron, and manganese; and/or iii) both I) and ii) above; b) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises:

I) ammonia; and ii) one or more ammonium salts; and iii) optionally one or more additional reductants; c) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metal-pregnant solution; d) optionally contacting the target metal-pregnant solution with one or more oxidants, and/or maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and e) separating the solution from the one or more precipitated non-target metals; and f) recovering the at least one target metal from the target metal-pregnant solution.

3. A method of recovering one or more target metals from a solution, wherein the solution comprises dissolved metal ions of at least one target metal, the method comprising: a) providing a solution comprising dissolved metal ions of at least one target metal, wherein one of the at least one target metals is lithium, and the solution has been prepared in a method comprising: i) contacting a feedstock comprising or consisting of black mass, said black mass comprising lithium and optionally one or more other target metals, and one or more non-target metals;

II) contacting the feedstock with a first leach solution in the presence of one or more reductants in a reductive leach step, wherein the first leach solution comprises:

(a) ammonia; and

(b) one or more ammonium salts; and

(c) optionally one or more additional reductants; iii) maintaining the reductive leach step for a time and under conditions suitable for dissolution of at least some of the one or more target metals to form a target metalpregnant solution; b) optionally contacting the target metal-pregnant solution with one or more oxidants, and/or maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals; and c) separating the solution from the one or more precipitated non-target metals; and d) recovering the at least one target metal from the target metal-pregnant solution.

4. The method according to any one of claims 1 to 3, wherein after the formation of the target metal-pregnant solution, the method comprises contacting the target meta I -pregnant solution with one or more oxidants and/or maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals.

5. The method according to any one of claims 1 to 4 wherein at least some of the solid feedstock residue present in or formed during the reductive leach step is removed during or after formation of the target meta I -pregnant solution.

6. The method according to claim 4 or 5 wherein at least some of the solid feedstock residue present in or formed during the reductive leach step is removed after formation of the target metal-pregnant solution and before contacting the target metal-pregnant solution with one or more oxidants and/or maintaining the target metal-pregnant solution for a time and under oxidising conditions suitable for precipitation of one or more non-target metals.

7. The method according to any one of claims 1 to 6 wherein the target metal is selected from the group consisting of lithium, nickel, and cobalt.

8. The method according to any one of the preceding claims wherein the target metal is lithium.

9. The method according to any one of the preceding claims wherein the feedstock material is selected from the group consisting of e-waste, one or more lithium ion batteries or a derivative or waste stream therefrom such as black mass, and a combination of any two or more thereof.

10. The method according to any one of the preceding claims wherein the feedstock material is black mass.

11. The method according to any one of the preceding claims, wherein the one or more ammonium salts is selected from the group consisting of ammonium chloride, ammonium sulphate, ammonium carbonate, and ammonium acetate.

12. The method according to any one of the preceding claims, wherein the one or more reductants is a metal.

13. The method according to any one of the preceding claims, wherein the one or more reductants is a non-target metal.

14. The method according to any one of the preceding claims, wherein the one or more reductants is a metal selected from the group consisting of iron, aluminium, manganese, copper, or zinc.

15. The method according to any one of the preceding claims, wherein the one or more reductants is a target metal selected from nickel or cobalt.

16. The method according to any one of the preceding claims, wherein the one or more additional reductants is a non-metallic reductant.

17. The method according to any one of the preceding claims, wherein the one or more additional reductants is selected from the group consisting of ferrous salts such as ferrous sulfate, activated carbon, organic acids, hydrazines, hydrides, borohydrides, and inorganic acids.

18. The method according to any one of the preceding claims wherein the maintaining step in which the oxidant is in contact with the target metal-pregnant solution or the oxidising conditions are maintained is maintained for between about 0.5 and 48 hours.

19. The method according to any one of the preceding claims wherein the maintaining step in which the oxidant is in contact with the target metal-pregnant solution or the oxidising conditions are maintained is maintained at a temperature of between about 20 °C to about 80 °C.

20. The method according to any one of the preceding claims, wherein recovery of the at least one target metal from the target metal-pregnant solution comprises at least one of: a) addition of a pH raising agent; b) addition of a Nickel precipitating agent; c) solvent extraction; d) removal of ammonia, for example by evaporation by thermal means or under reduced pressure; e) any combination of any two or more of a) to d) above; followed by at least one of: f) addition of a reducing agent, such as sodium bisulfite or hydrogen gas; g) heating, for example to at least about 80 °C, in the presence of a reducing agent, for example hydrazine hydrate; h) electrolysis; i) thermally induced base hydrolysis, for example by heating to a high temperature (e.g., 80-200°C), plus addition of a strong base, such as sodium hydroxide (NaOH) or potassium hydroxide (KOH); j) any combination of any two or more of f) to I) above followed by addition of a pH raising agent, such as a hydroxide salt, for example CaOH, together with a carbonate salt, such as sodium carbonate, optionally together with one or more of: k) evaporation of the target metal-pregnant solution; l) membrane-based concentration, such as reverse osmosis; m) each of k) and I) above.

21. The method according to any one of the preceding claims, wherein when the feedstock comprises black mass and/or the feedstock comprises graphite, the method comprises a graphite recovery step.

22. The method according to any one of the preceding claims wherein the target metal-pregnant solution is an aqueous solution containing more than lOOppm of a target metal.

23. The method according to any one of the preceding claims wherein at least about 90% of a target metal is recovered.

24. The method according to claim 23 wherein at least about 90% of each target metal is recovered.

25. The method according to claim 24 wherein at least about 99% of each target metal present in the feedstock is recovered.

26. The method according to any one of the preceding claims, the method comprising: a) subjecting the target meta I -pregnant solution to a Nickel recovery step to yield a low- Nickel solution; b) subjecting the low-Nickel solution to a Cobalt recovery step to yield a low-Cobalt solution; c) subjecting the low-Cobalt solution to a Lithium recover step to yield a Lithium precipitate.

27. The method according to claim 26 wherein the Nickel recovery step comprises addition of a pH raising agent; and/or the Cobalt recovery step comprises addition of metallic Cobalt.

28. The method according to claim 26 or claim 27, wherein: a) the low-Nickel solution comprises a Nickel concentration less than about 15% of the Nickel concentration of the target metal-pregnant solution; or b) the low-Co solution comprises a Co concentration less than about 15% of the Cobalt concentration of the low Nickel solution; or c) both a) and b) above.

29. The method according to any one of the preceding claims wherein at least some of any ammonia removed is collected and/or reused.