Method for recovering one or more metal species

Abstract

The present invention relates to a process for recovering one or more metal species from a raw material, such as a spent lithium ion battery material, comprising: providing a molten salt comprising at least one metal hydroxide, providing one or more oxyacidity agents, preferably as a reservoir of one or more oxyacidity agents in communication with the molten salt, the oxyacidity of the molten salt is set to an oxyacidity value at which at least one metal substance is dissolved in the molten salt with the one or more oxyacidity agents, and the raw material is brought into contact with the molten salt, at least one of steps b) and c) is performed: b) setting the potential of the molten salt to recover the first metal species as a first metal or a first metal oxide, c) adjusting the oxyacidity of the molten salt with the one or more oxyacidity agents to precipitate the first metal oxide, d) for one or more additional metal species, optionally, at least one of method steps a) and / or method steps b) and c) is performed.

Description

Technical Field

[0001] The present invention relates to a method for recovering one or more metal substances as metals or metal oxides. These metal substances (such as metals or metal oxides) are recovered from raw materials such as waste lithium-ion battery materials. Background Art

[0002] The extraction of materials (such as metals) from raw materials is used in many technical fields. Extraction techniques vary in their technical nature. Pyrometallurgy relies on heating raw materials to convert metal oxides into metals or metal compounds. Roasting materials involves heating in a vacuum or inert atmosphere to convert metal oxides into mixed metal alloys containing them. Pyrometallurgical methods are energy-intensive but require simpler mechanical pretreatment methods. Hydrometallurgical methods are within the scope of aqueous chemistry, and the extraction technique is a key element of these methods for recovering metals or metal compounds from raw materials. Extraction is conventionally carried out with H2SO4 and H2O2, or HCl, HNO3, and organic acids. Thereafter, precipitation techniques along different paths are followed to selectively recover metal compounds or precursors of the desired metals or metal compounds.

[0003] The extraction and recovery of metal compounds are carried out in metal ore processing, waste management, and the recycling of electronic components (such as the recycling of lithium-ion batteries).

[0004] It is well known to recycle lithium-ion batteries and recover metals and metal compounds therefrom.

[0005] US20220131204 discloses a method in which depleted lithium-ion batteries are dissolved in a solution for extracting, for example, Co and Ni to produce new cathode materials for lithium-ion batteries. Several dissolution solutions are used, and sulfuric acid leaching is used to leach the crushed waste cathode powder. After the separation step, elements in the solution such as Co ions are transferred to an aqueous hydroxide solution to precipitate lower-value metals as hydroxides. If necessary, the content of, for example, Co in the solution that still contains the metal to be recovered is then adjusted. Then, Na2CO3 is added to the solution to extract Li compounds, and the remaining desired metals are recovered as composite hydroxides (such as Ni 1 / 3 Mn 1 / 3 Co 1 / 3 O(OH)), and the composite hydroxide is used in a high-temperature process at 900 °C to sinter into a composite oxide as the final product. This process involves several waste streams from several dissolution solutions and treatment solutions.

[0006] The following article discloses the recovery of Co from spent LCO-based batteries: "A Green Electrochemical Process to Recover Co and Li from Spent LiCoO2-Based Batteries in Molten Salts [A Green Electrochemical Process to Recover Co and Li from Spent LiCoO2-Based Batteries in Molten Salts], ACS Sustainable Chem. Eng. [ACS Sustainable Chemistry and Engineering] 2019, 7, 13391-13399". Spent LCO (LiCoO2) is electrochemically reduced to CoO or Co at the cathode at a controlled potential, and Li2O is released into the molten salt, where Li2O combines with CO2 generated at the carbon anode to produce Li2CO3. The molten salt used is a Na2CO3-K2CO3 salt and is thus a carbonate-based salt. Li2O is captured and reacted with CO2 to form Li2CO3. No mention is made of using a molten salt containing metal hydroxides.

[0007] WO 2018 / 229265 discloses a molten salt nuclear fission reactor (MSR) that has a molten metal hydroxide as a moderator salt. The molten moderator salt can contain a redox element with a reduction potential greater than that of the material in contact with the molten moderator salt, or a chemical substance (such as water) that controls the oxygen acidity of the molten moderator salt. The purpose of using a chemical substance that controls oxygen acidity in WO 2018 / 229265 is to minimize the corrosion of the reactor wall material, which typically includes Ni-containing alloys. Summary of the Invention

[0008] An object of the present invention is to provide a method for recovering metal substances (such as metals or metal oxides) from raw materials, which uses a less energy-intensive process or obtains higher purity compared to conventional processes, and produces less waste (both liquid and gaseous waste) compared to conventional processes.

[0009] Another object of the present invention is to provide a simpler method for recovering metal substances from waste lithium-ion battery materials for use as raw materials for new lithium-ion batteries, and which does not produce the large amounts of harmful liquid and gaseous waste found in most conventional processes.

[0010] According to one aspect of the present invention, there is provided a method for recovering one or more metal substances from raw materials (such as waste lithium-ion battery materials), the method comprising:

[0011] - providing a molten salt comprising at least one metal hydroxide

[0012] - Provide one or more oxoacidity agents, preferably as a reservoir for one or more oxoacidity agents in communication with the molten salt

[0013] a) Set the oxoacidity of the molten salt with one or more oxoacidity agents to an oxoacidity value that dissolves at least one metal substance in the molten salt

[0014] - Bring the raw material into contact with the molten salt

[0015] - Perform at least one of steps b) and c):

[0016] b) Set the potential of the molten salt to recover the first metal substance as the first metal or the first metal oxide

[0017] c) Adjust the oxoacidity of the molten salt with one or more oxoacidity agents to precipitate the first metal oxide

[0018] d) Optionally, for one or more additional metal substances, perform method step a) and / or perform at least one of method steps b) and c).

[0019] In a further aspect, the present invention relates to

[0020] A system for recovering one or more metal substances from a raw material (such as waste lithium-ion battery material), preferably for use in a method as defined above, the system comprising:

[0021] - A container for a molten salt containing at least one metal hydroxide

[0022] - A reservoir containing water vapor, the reservoir being in communication with the bottom section of the container, and the bottom section including a sparger

[0023] - Two or more electrodes in contact with the molten salt of at least one metal hydroxide Detailed description

[0024] A method for recovering one or more metal substances from a raw material (such as waste lithium-ion battery material) includes:

[0025] - Provide a molten salt containing at least one metal hydroxide

[0026] - Provide one or more oxoacidity agents, preferably as a reservoir for one or more oxoacidity agents in communication with the molten salt

[0027] a) Set the oxoacidity of the molten salt with one or more oxoacidity agents to an oxoacidity value that dissolves at least one metal substance in the molten salt

[0028] - Bring the raw material into contact with the molten salt

[0029] - Perform at least one of steps b) and c):

[0030] b) Set the potential of the molten salt to recover the first metal substance as the first metal or the first metal oxide.

[0031] c) Adjust the oxygen acidity of the molten salt with one or more oxygen acidity agents to precipitate the first metal oxide.

[0032] d) Optionally, for one or more additional metal substances, perform method step a) and / or perform at least one of method steps b) and c).

[0033] In one embodiment, the above method is used to recover at least two metal substances, such as the first metal substance and the second metal substance; such as at least three metal substances, such as the first metal substance, the second metal substance, and the third metal substance.

[0034] We have found that providing a molten salt having at least one metal hydroxide has many advantages. The metal hydroxide melt has a certain oxygen acidity value. Various metal compounds of the raw materials in contact with the molten hydroxide may dissolve or not dissolve to a large extent at this oxygen acidity value. Therefore, metal substances can be preferentially and separately dissolved, and this is utilized in the method. By adding an oxygen acidity agent (such as H2O) to the molten hydroxide salt to set or adjust the oxygen acidity, a single metal substance can be dissolved. Then, the formed metal substance can be further processed to recover a specific free metal from the raw material or to recover the oxide of a specific metal. The inventors of the present invention have surprisingly found that the metals recovered in this way have satisfactory purity. The recovered materials provided by the embodiments according to the present invention have a certain purity, enabling optional further processing to obtain commercially valuable products. The advantages of the present invention are relatively easy. By the present invention, by adjusting the oxygen acidity value by adding, for example, H2O to the metal hydroxide melt, individual metals can be recovered. Metal hydroxides (such as sodium hydroxide) together with H2O as the oxygen acidity agent are still very inexpensive raw materials, so large-scale processes are relatively inexpensive. It is also possible to recover the metal substance as a metal oxide rather than a metal. The advantage of the present invention is that it is relatively easy to choose between alternatives for recovering the metal substance as a metal or a metal oxide using the same means as above, which means providing a molten salt of a metal hydroxide and using H2O as the oxygen acidity agent. Therefore, the method according to the present invention is very versatile when deciding which metal substances should be recovered from the raw materials and in what specific substances they should be recovered.

[0035] Given the correct combination of the temperature of the salt and the oxygen acidity value of the salt, many raw materials will dissolve in the molten salt of metal hydroxide. Therefore, the advantage of the method according to the present invention is its usefulness for recovering metals and metal oxides from a large number of different raw materials.

[0036] The raw materials may include metal compounds such as metal oxides. When the raw materials come into contact with the molten salt of metal hydroxide and the dissolution of the raw materials occurs, the metal compounds of the raw materials form dissolved metal substances such as ionic metal substances.

[0037] In one embodiment, the metal substance is a metal ion.

[0038] In one embodiment, the metal substance is a metal ion associated with an oxygen ion. An example is the Ni compound that forms NiO2 containing Ni 2+ and two O 2- . -2

[0039] In one embodiment, the metal substance is a metal hydroxide such as a composite hydroxide.

[0040] In one embodiment, the molten salt contains a material for surface-promoted recovery for precipitating the metal substance.

[0041] The material for surface-promoted recovery is a material in which the precipitation of the metal substance in the molten salt preferentially occurs compared to other materials in contact with the molten salt and the electrodes in contact with the molten salt, and the other materials have, for example, the surface of the container wall for the molten salt.

[0042] In one embodiment, the material for surface-promoted recovery for precipitating the metal substance includes a network structure.

[0043] The material for surface-promoted recovery is preferably a high-surface-area material.

[0044] The material should have low corrosion at the main oxygen acidity and electrochemical potential during precipitation in the molten salt.

[0045] In one embodiment, the material is selected from the group consisting of: Mo and Mo alloys, Ni and Ni alloys, Pt, ceramic materials (such as alumina).

[0046] The dissolved metal substance can be recovered as a metal substance that is a metal or as a metal substance that is a metal oxide.

[0047] In one embodiment, the raw materials substantially do not contain metals in their metallic state.

[0048] In one embodiment, the raw material contains a metal in its metallic state with an impurity level. In one embodiment, the raw material contains a metal oxide complex, such as a Co oxide complex.

[0049] In one embodiment, the material is an iron ore material.

[0050] The metal substance can constitute a major part of the raw material to be used or the pre-treated raw material in the method according to the present invention.

[0051] In one embodiment, the raw material or the pre-treated raw material contains more than 90 wt.%, such as more than 80 wt.%, such as more than 70 wt.%, such as more than 60 wt.% of the raw material or the pre-treated raw material, all percentages being based on the total weight of the raw material or the pre-treated raw material.

[0052] Waste lithium-ion battery materials

[0053] Lithium-ion (secondary) batteries are widely used in electronic devices such as mobile phones. Due to the use and expiration of lithium-ion secondary batteries, these batteries become waste, or may be discarded due to defects or other reasons.

[0054] Waste lithium-ion battery materials typically include the cathode material for lithium-ion (secondary) batteries.

[0055] The waste contains valuable metals such as cobalt and nickel, which are commercially attractive for recovery in high purity, for example for reuse in manufacturing new lithium-ion batteries or other purposes. The oxides of cobalt and nickel are also commercially attractive for recovery in high purity.

[0056] In one embodiment, the waste lithium-ion battery material contains cobalt and nickel as elements in the form of compounds, preferably up to 30 wt.% of cobalt and up to 30 wt.% of nickel.

[0057] Lithium-ion batteries typically have a lid or housing made of aluminum as the outer cover of the battery. The electrode materials are included in the housing. The cathode material can contain a single metal oxide or two or more composite metal oxides of elements lithium, nickel, manganese, and cobalt. The cathode material can be applied to an aluminum-containing substrate.

[0058] Organic compounds such as polyvinylidene fluoride binder (PVDF) and organic electrolytes such as carbonates, such as ethylene carbonate and diethyl carbonate, can also be present in the waste lithium-ion battery material.

[0059] In one embodiment, the waste lithium-ion battery material is in the form of a powder that has been processed. The purpose of the processing is to make the waste lithium-ion battery material suitable for dissolution in a molten salt containing at least one metal hydroxide. The processing can be roasting, such as roasting to remove organic substances from the waste lithium-ion battery material.

[0060] In one embodiment, the waste lithium-ion battery material is pretreated, such as by roasting before dissolving in a molten salt containing at least one metal hydroxide.

[0061] Roasting involves heating the battery waste, such as at a temperature of 450 °C to 1000 °C, such as 600 °C to 800 °C, for example for 15 minutes to 5 hours.

[0062] In one embodiment, the waste lithium-ion battery material is not roasted before being dissolved in a molten salt containing at least one metal hydroxide.

[0063] This has the advantage of providing a less energy-intensive pretreatment for the waste lithium-ion battery material.

[0064] In one embodiment, the raw material is waste lithium-ion battery material.

[0065] In one embodiment, the waste lithium-ion battery material contains a single metal oxide of one or more of the elements lithium, nickel, manganese, and cobalt, or two or more composite metal oxides.

[0066] In one embodiment, the waste lithium-ion battery material includes electrode material, such as cathode material.

[0067] In one embodiment, the raw material includes one or more waste lithium-ion battery materials based on oxides selected from the group consisting of:

[0068] Lithium nickel manganese cobalt oxide (NMC, LiNi x Mn y Co z O2),

[0069] Lithium nickel cobalt aluminum oxide (NCA, LiNiCoAlO2),

[0070] Lithium manganese oxide (LMO, LiMn2O4),

[0071] Lithium iron phosphate (LFP, LiFePO4),

[0072] Lithium cobalt oxide (LCO, LiCoO2).

[0073] A molten salt containing at least one metal hydroxide

[0074] Metal hydroxides such as NaOH are inexpensive chemicals used in various chemical processes. Depending on the need, the metal hydroxide can be any metal hydroxide, but the metal hydroxide is preferably a hydroxide of an alkali metal, such as sodium hydroxide, potassium hydroxide, rubidium hydroxide or lithium hydroxide or a mixture thereof, or the metal hydroxide can be a hydroxide of an alkaline earth metal (such as calcium or magnesium). Similarly, the metal hydroxide can be a hydroxide of different metals.

[0075] In one embodiment, the metal hydroxide is one or more hydroxides selected from the group consisting of NaOH, KOH, LiOH and RbOH, such as NaOH.

[0076] The temperature of the molten salt should be set higher than the melting temperature of the salt, at least high enough to ensure that the molten salt will not freeze. The specific choice of temperature also depends on the metal substances to be recovered from the raw materials. If the raw materials contain multiple metal substances, each of these metal substances can generally have different oxygen acidity values at which it is dissolved. The difference in oxygen acidity values between various metal substances varies with temperature, and the difference at one temperature may be greater than the difference at another temperature.

[0077] The temperature of the molten salt is preferably in the range of 100 °C - 1300 °C, such as 170 °C - 1300 °C, such as 300 °C - 1000 °C, such as 350 °C - 800 °C, such as 400 °C - 600 °C.

[0078] When the molten salt of metal hydroxide is in a container, the molten salt of metal hydroxide can be stationary, or the molten salt of metal hydroxide can circulate in the container by natural convection, forced convection or forced circulation. Generally, forced circulation involves stirring the molten salt of metal hydroxide. Any kind of stirring can be used in this method. Pumping the molten salt of metal hydroxide can also be a device for circulating the molten salt. In this context, natural convection is considered to involve the movement occurring in the molten salt of metal hydroxide due to the temperature and / or component concentration gradient of the molten salt of metal hydroxide without any active steps being taken to affect the convection. In this context, when no active steps are taken to create a temperature and / or concentration gradient, the molten salt of metal hydroxide is generally considered to be stationary. In contrast, forced convection is considered to involve the movement in the molten salt of metal hydroxide caused by the active introduction of a temperature and / or concentration (especially temperature) gradient. For example, local heating of a certain volume of the molten salt of metal hydroxide can cause local expansion of the molten salt of metal hydroxide near the heat source, which results in movement in the molten salt of metal hydroxide. Similarly, local cooling of a certain volume of the molten salt of metal hydroxide can cause local contraction of the molten salt of metal hydroxide near the radiator, which results in movement in the molten salt of metal hydroxide. Forced convection and forced circulation generally make the oxygen acidity in the molten salt of metal hydroxide uniform. In this context, forced circulation can be represented by volume displacement over time and is in units of per hour (or h -1 ), for example, the volume displacement can be in the range of 0.1 h -1 to 100 h -1 , for example, 1 h -1 to 20 h -1 .

[0079] Oxygen acidity agent

[0080] The molten salt can contain water and other components that will help define the property "oxygen acidity" of the molten salt. In the molten salt containing hydroxide, the hydroxide ion is an amphoteric substance that can accept a proton to become H2O or can donate a proton to become an oxygen ion O 2- . The water present in the molten salt reacts through Equation 2

[0081] Equation 1

[0082] Equation 2

[0083] In this context, we define oxygen acidity as pH2O = -log 10 [H2O], and oxygen basicity is pO 2- = -log 10 [O2- , similar to the well-known pH = -log in aqueous chemistry 10 [H + and pOH = -log 10 [OH - .

[0084] The dimensionless quantity paH2O can also be used to characterize the oxoacidity of molten salts of metal hydroxides, where "a" represents the activity of H2O. Both pH2O and paH2O will be used hereinafter.

[0085] In one embodiment, the temperature of the molten salt of the metal hydroxide is selected such that the oxoacidity for dissolving the first metal compound is different from the oxoacidity for dissolving the second metal compound, and the difference in oxoacidity between the first metal compound and the second metal compound is in the range of pa[H2O] = 0.1 - 2.0, such as pa[H2O] = 0.2 - 1.5, pa[H2O] = 0.3 - 1.1, or pa[H2O] = 0.4 - 0.8.

[0086] In this context, an oxoacidity agent can be any chemical entity, such as an element, molecule or ion, which can affect the concentration of at least one of OH - , O 2- and H2O in molten salts, especially molten salts of metal hydroxides. The effect on the concentration of at least one of OH - , O 2- and H2O can be direct or indirect, and the effect can involve, for example, increasing or decreasing the concentration according to Equation 2.

[0087] In one embodiment, the oxoacidity agent is one or more compounds selected from the group consisting of OH - , O 2- and H2O, such as H2O.

[0088] In particular, in the context of this method, all OH - , O 2- and H2O are considered oxoacidity agents, and similarly, those containing OH - or O 2-Molecules with appropriate counterions are also considered to be oxygen-containing acidity regulators. In particular, water (H2O) in the form of vapor is a preferred oxygen-containing acidity regulator. Water (H2O) can also exist as a hydrate in a salt or crystal, and a salt containing a water hydrate can also be used as an oxygen-containing acidity regulator. When a salt contains a water hydrate, the number of water molecules in the salt is typically expressed as "·xH2O" together with the stoichiometric composition of the salt, and the value of x can be used to determine the amount of the salt to adjust the oxygen-containing acidity. Other oxygen-containing acidity regulators are metal oxide salts, such as oxide salts of the same metal as the molten salt of the metal hydroxide. In this context, those capable of binding to or supplying OH - 、O 2- and / or H2O or supplying OH - 、O 2- and / or H2O are also considered to be oxygen-containing acidity regulators.

[0089] The oxygen-containing acidity regulator can be present in the metal hydroxide before the salt is melted, and thus once melted, the oxygen-containing acidity regulator will also be present in the metal hydroxide salt. However, due to the typically high temperatures used for molten salts and due to the possible reaction between the oxygen-containing acidity regulator and other components leading to equilibrium changes, the content of the oxygen-containing acidity regulator will not be constant over time. For example, the oxygen-containing acidity regulator can evaporate from the molten salt.

[0090] A reservoir including one or more oxygen-containing acidity regulators provides a means for supplying the oxygen-containing acidity regulator to a molten salt containing at least one metal hydroxide.

[0091] The reservoir can be any kind of container, pipe, or line. The connection or interface between the molten salt and one or more oxygen-containing acidity regulators in the reservoir can be achieved with any kind of container, pipe, or line.

[0092] In one embodiment, the reservoir includes a processing gas containing the oxygen-containing acidity regulator. The processing gas is brought into contact with the molten salt of the metal hydroxide. Thereby, the oxygen-containing acidity regulator is also brought into contact with the molten salt of the metal hydroxide, and the oxygen-containing acidity of the molten salt of the metal hydroxide can be adjusted. Generally, the amount of the oxygen-containing acidity regulator brought into contact with the molten salt of the metal hydroxide is determined by the concentration of the oxygen-containing acidity regulator in the processing gas, the pressure of the processing gas, and the amount of the processing gas brought into contact with the molten salt of the metal hydroxide (e.g., expressed as unit volume per unit time, such as m 3 / min). The processing gas can contain argon or nitrogen. The amount of the oxygen-containing acidity regulator related to a specific example of the method is determined by: one or more estimations of the concentration of at least one of OH - 、O 2- and H2O in the molten salt of the metal hydroxide and the selected oxygen-containing acidity regulator and the OH - 、O2- The chemical reaction equilibrium between one or more of

[0093] When the gas contains an oxygen-containing acidity agent, the gas can be bubbled through the molten salt of the metal hydroxide by means of an ejector.

[0094] When the gas contains an oxygen-containing acidity agent, the volume of the gas bubbling through the molten salt of the metal hydroxide takes into account the expected amount of the oxygen-containing acidity agent to be contacted with the molten salt of the metal hydroxide, and the amount of the gas bubbling through the molten salt of the metal hydroxide can be expressed as the volume of the inert gas per unit time relative to the volume of the molten salt of the metal hydroxide, so the unit can be per hour (or h -1 ). The volume of the inert gas bubbling through the molten salt of the metal hydroxide can be in the range of 0.1 h -1 to 10 h -1 , for example, 0.5 h -1 to 2 h -1 . When the gas bubbles through the molten salt of the metal hydroxide, the bubbles may cause a forced circulation of the molten salt of the metal hydroxide, especially when the volume of the gas bubbling through the molten salt of the metal hydroxide is higher than 2 h -1 .

[0095] In one embodiment, the gas bubbling through the molten salt of the metal hydroxide is an inert gas (i.e., an inert gas without an oxygen-containing acidity agent), a processing gas having an oxygen-containing acidity agent, or an oxygen-containing acidity agent in gaseous form.

[0096] In one embodiment, a processing gas containing an oxygen-containing acidity agent is brought into contact with the molten salt of the metal hydroxide,

[0097] The oxygen-containing acidity agent can also be added to the molten salt of the metal hydroxide without using a processing gas. For example, a solid metal oxide (such as lithium or sodium oxide) can be added to the molten salt in the form of solid granules in a suitable amount to achieve the target concentration of any one of OH - , O 2- and H2O in the molten salt of the metal hydroxide. In another example, molten potassium hydroxide hexahydrate can be titrated into the molten salt of the metal hydroxide to achieve the target concentration of any one of OH - , O 2- and H2O. An oxide (such as Li2O or Na2O) can also be brought into contact with the molten salt of the metal hydroxide.

[0098] The oxygen-containing acidity can be expressed as one of OH - , O 2- and H2O, or the oxygen-containing acidity can be expressed as OH - , O2- and combinations of two or all three of OH - , O 2- and H2O contribute to the oxygen acidity, and by estimating the oxygen acidity of OH - , O 2- and H2O, one, two or all three of them, and bringing the molten salt of metal hydroxide into contact with a processing gas containing an oxygen acidity agent, the oxygen acidity of the molten salt of metal hydroxide can be adjusted and / or set within a desired range of oxygen acidity values, for example, according to Henry's law. Generally, it is assumed that when the oxygen acidity agent is provided in a gaseous form, the amount of the oxygen acidity agent dissolved in the molten salt of metal hydroxide is proportional to the partial pressure of the oxygen acidity agent in contact above the molten salt of metal hydroxide, for example.

[0099] Setting or adjusting the oxygen acidity of the molten salt

[0100] The metallic substance of the raw material will exist in a given phase among multiple possible phases of the metallic substance in the molten salt of at least one hydroxide. The dominant phase of the first metal compound is determined by the temperature and composition of the molten salt of the hydroxide, as well as the redox potential and oxygen acidity value of the molten salt of the hydroxide.

[0101] In order to set or adjust the oxygen acidity value of the molten salt to recover the metallic substance in a preferred phase (for example, in the metallic state), a preliminary estimate can be made from the calculation of a graph of the equilibrium redox potential versus oxygen acidity (for example, E versus p(H2O)) to determine the oxygen acidity value. Such a graph will show the phase of the metal compound selected at a given oxygen acidity value.

[0102] Thereafter, the oxygen acidity value of the molten salt is set / adjusted according to the graph, taking into account the purposes, such as the purpose of dissolving the raw material or precipitating the metallic substance as a metal oxide.

[0103] The construction of the E versus p(H2O) graph is derived from thermodynamic data. The basic steps for constructing the thermodynamic graph are described below:

[0104] Consider all equilibrium reactions between different chemical substances of the same element. Select the Na + / Na redox pair as the reference system for selecting NaOH as the molten salt of metal hydroxide.

[0105] Use the thermodynamic data of pure substances to calculate the Gibbs free energy and equilibrium constant of all equilibrium reactions. The thermodynamic data can be calculated using, for example, HSC chemistry 6.0 software or obtained experimentally.

[0106] For all proposed equilibrium reactions, the equilibrium redox potential is then calculated by the attached Nernst equation.

[0107] For NaOH molten salts and raw materials containing Mn oxide, Ni oxide, and Co oxide, the resulting diagrams at 350 °C according to such procedures are respectively shown in Figure 1a , Figure 1b and Figure 1c .

[0108] The metallic substance can exist as a metallic substance of metal ions associated with oxygen ions in some phases. For example, Ni can exist as NiO2 2+ containing Ni 2- and two O -2 in the phase. In other phases, the metallic substance can be metal ions.

[0109] The oxygen acidity in the molten salt can be set / regulated by using the relationship between the partial pressure of water in the gas in a reservoir containing an oxygen acidity agent, the reservoir being in communication with the molten salt.

[0110] In most cases, the oxygen acidity values obtained from the calculated E vs. p(H2O) diagrams can be supplemented with data from electrochemical experiments. The availability of these diagrams and their applicability may be limited by the thermodynamic data available in the database. Therefore, chemical and electrochemical experiments are usually required to complete and validate the validity of the thermodynamic diagrams.

[0111] By way of illustration, the following electrochemical experiment can be suitable for the combination of Co oxide in molten hydroxide salts: After evaluating the thermodynamic data of the raw materials in the molten hydroxide, the redox and chemical equilibria of the selected materials are established. Two chemical substances forming a redox pair (such as Co(III) / Co(II) or Co(II) / Co) are introduced into the melt at known concentrations. The ratio of the redox pair determines the equilibrium potential of the molten hydroxide salt. Open-circuit potential measurements are recorded under different oxygen acidity conditions.

[0112] In one embodiment, the oxygen acidity is set to the value of the parameter pa(H2O).

[0113] In one embodiment, the oxygen acidity is adjusted to the value of the parameter pa(H2O).

[0114] Setting or adjusting the oxygen acidity to the value of, for example, the parameter pa(H2O) can be carried out with the same device as the device for supplying an oxygen acidity agent to the molten salt of the metal hydroxide.

[0115] In one embodiment, the oxygen acidity of the molten salt is set to a value that dissolves the raw material as a metallic substance in the molten salt with one or more oxygen acidity agents, and then the raw material is brought into contact with the molten salt.

[0116] Therefore, the oxygen acidity value is set to a value at which it will dissolve the raw material containing one or more metal substances, and then the raw material containing the metal substance is brought into contact with the molten salt.

[0117] This embodiment of the present invention, in which the molten salt is prepared before contacting the raw material, has the following advantages: the dissolution reaction will occur from the very beginning, where the oxygen acidity value is designed according to the E vs. oxygen acidity diagram and electrochemical tests.

[0118] In one embodiment, the raw material is brought into contact with the molten salt, and then the oxygen acidity of the molten salt is set with one or more oxygen acidity agents to a value at which the raw material dissolves as metal substances in the molten salt.

[0119] Therefore, the oxygen acidity value is set to a value at which the first metal compound will dissolve when the raw material containing the metal substance is in contact with and present in the molten salt.

[0120] This embodiment of the present invention, in which the raw material is in contact with the molten salt during the adjustment of the oxygen acidity value of the molten salt, has the following advantages: the dissolution reaction will occur from the moment of contact. This avoids any long - term adjustment of the oxygen acidity value before dissolution can occur. The dissolution of the raw material containing the metal compound can still occur to some extent even if the designed oxygen acidity value has not been reached through adjustment.

[0121] In one embodiment, the oxygen acidity is adjusted during the process of dissolving the raw material.

[0122] In one embodiment, the oxygen acidity is adjusted during the process of electroplating a metal or metal oxide from the metal substance.

[0123] In one embodiment, during the process of electroplating a metal or metal oxide from the metal substance, the oxygen acidity is adjusted with hydrogen.

[0124] In one embodiment, the oxygen acidity is adjusted during the process of precipitating a metal oxide from the metal substance.

[0125] In one embodiment, a method for recovering one or more metal substances from a raw material (such as waste lithium - ion battery material) includes:

[0126] - providing a molten salt containing at least one metal hydroxide

[0127] - providing one or more oxygen acidity agents, preferably as a reservoir of one or more oxygen acidity agents in communication with the molten salt

[0128] a) setting the oxygen acidity of the molten salt with one or more oxygen acidity agents to an oxygen acidity value at which at least one metal substance dissolves in the molten salt

[0129] - Contact the raw material with the molten salt

[0130] - Perform at least one of steps b) and c):

[0131] b) Set the potential of the molten salt to recover the first metal substance as the first metal or the first metal oxide,

[0132] c) Adjust the oxygen acidity of the molten salt with one or more oxygen acidity agents to precipitate the first metal or the first metal oxide,

[0133] d) Optionally, for one or more additional metal substances, perform method step a) and perform at least one of method steps b) and c).

[0134] In one embodiment, a method for recovering one or more metal substances from a raw material (such as waste lithium-ion battery material) includes:

[0135] - Provide a molten salt containing at least one metal hydroxide

[0136] - Provide one or more oxygen acidity agents, preferably as reservoirs of one or more oxygen acidity agents in communication with the molten salt

[0137] a) Set the oxygen acidity of the molten salt with one or more oxygen acidity agents to an oxygen acidity value that allows at least one metal substance to dissolve in the molten salt

[0138] - Contact the raw material with the molten salt

[0139] - Perform at least one of steps b) and c):

[0140] b) Set the potential of the molten salt to recover the first metal substance as the first metal or the first metal oxide,

[0141] c) Adjust the oxygen acidity of the molten salt with one or more oxygen acidity agents to precipitate the first metal or the first metal oxide,

[0142] d) Optionally, for one or more additional metal substances, perform method step a) or perform at least one of method steps b) and c).

[0143] In one embodiment, a method for recovering one or more metal substances from a raw material (such as waste lithium-ion battery material) includes:

[0144] - Provide a molten salt containing at least one metal hydroxide

[0145] - Provide one or more oxygen acidity agents, preferably as reservoirs of one or more oxygen acidity agents in communication with the molten salt

[0146] a) Set the oxygen acidity of the molten salt with one or more oxygen acidity agents to an oxygen acidity value that allows at least one metal substance to dissolve in the molten salt.

[0147] - Bring the raw material into contact with the molten salt.

[0148] - Perform at least one of steps b) and c):

[0149] b) Set the potential of the molten salt to recover the first metal substance as the first metal or the first metal oxide.

[0150] c) Adjust the oxygen acidity of the molten salt with one or more oxygen acidity agents to precipitate the first metal or the first metal oxide.

[0151] d) Optionally, for one or more additional metal substances, perform method step a) and / or perform at least one of method steps b) and c).

[0152] In one embodiment, waste lithium-ion battery material containing metal substances is brought into contact with the molten salt. Set the oxygen acidity to dissolve the raw material into the first metal substance.

[0153] Apply a potential to reduce the first metal substance to the first metal. Thereafter, set the oxygen acidity to dissolve the raw material into the second metal substance. Apply a potential to reduce the second metal substance to the second metal, and preferably thereafter set the oxygen acidity to dissolve the raw material into the third metal substance. Apply a potential to reduce the third metal substance to the third metal.

[0154] The above three metal substances each have a preferred oxygen acidity value for dissolving them. For example, the oxygen acidity value pa[H2O] of the first metal substance < the pa[H2O] of the second metal substance < the pa[H2O] of the third metal substance.

[0155] The advantage of this embodiment of the present invention is that these metals can be separately recovered as substantially pure metals. Another advantage is that metal substance recovery can be performed on only one or only two or all three of the three metal substances, thus showing the versatility of the method.

[0156] This principle and versatility similarly apply to the case where the raw material contains two metal substances and the case where the raw material contains three or more metal substances.

[0157] In the above embodiment, the first metal can be Mn, and one or more additional metals can be selected from the group consisting of Al and transition metals (such as Fe, Co, Ni).

[0158] In one embodiment, waste lithium-ion battery material containing Mn oxide, Ni oxide, and Co oxide is brought into contact with the molten salt.

[0159] Set the oxygen-containing acidity to dissolve the raw material into Mn substance;

[0160] Apply a potential to reduce the Mn substance to Mn, and preferably thereafter set the oxygen-containing acidity to dissolve the raw material into Ni substance;

[0161] Apply a potential to reduce the Ni substance to Ni, and preferably thereafter set the oxygen-containing acidity to dissolve the metal compound into Co substance;

[0162] Apply a potential to reduce the Co substance to Co.

[0163] The advantage of this embodiment of the present invention is that the separation of Ni and Co in their corresponding substantially pure metal forms is achieved in a one-pot process. This is difficult to achieve with most of the processes known to date.

[0164] In one embodiment, set the oxygen-containing acidity to dissolve the raw material into first, second, and third metal substances,

[0165] Adjust the oxygen-containing acidity to precipitate the first metal substance as the first metal oxide, preferably thereafter adjust the oxygen-containing acidity to precipitate the second metal substance as the second metal oxide, and preferably thereafter adjust the oxygen-containing acidity to precipitate the third metal substance as the third metal oxide.

[0166] The above three metal substances each have different oxygen-containing acidity values for dissolving them, and the oxygen-containing acidity is set to dissolve all of them. Thereafter, utilize the difference in their oxygen-containing acidity to continuously precipitate metal oxides.

[0167] The advantage of this embodiment is that metal substances in their substantially pure oxide forms can be obtained, and furthermore this is accomplished in a one-pot process.

[0168] In the above embodiment, the first metal substance is Co substance, and one or more additional metal substances may be transition metal substances, such as transition metal substances selected from the group consisting of Fe, Mn, and Ni.

[0169] In one embodiment, contact a waste lithium-ion battery material containing Mn oxide, Ni oxide, and Co oxide with a molten salt. The oxygen-containing acidity is set to dissolve all the oxides. Thereafter, adjust the oxygen-containing acidity to precipitate the Co substance as Co oxide, preferably thereafter adjust the oxygen-containing acidity to precipitate the Ni substance as Ni oxide, and preferably thereafter adjust the oxygen-containing acidity to precipitate the Mn substance as Mn oxide.

[0170] In one embodiment, waste lithium-ion battery materials are contacted with a molten salt. The oxygen-containing acidity is set to dissolve the raw materials into a first metal substance; a potential is applied to reduce the first metal substance to a first metal, and preferably thereafter the oxygen-containing acidity is set to dissolve the second and third metal substances, and the oxygen-containing acidity is adjusted to precipitate the second metal substance as a second metal oxide, and preferably thereafter a potential is applied to reduce the third metal substance to a third metal.

[0171] The advantage of this embodiment of the present invention is that one metal substance can be selected for metal recovery, and other metal substances can be selected for recovery as their respective oxides, thus showing the versatility of the method.

[0172] In one embodiment, waste lithium-ion battery materials containing Mn oxide, Ni oxide, and Co oxide are contacted with a molten salt. The oxygen-containing acidity is set to dissolve the raw materials into a Mn substance; a potential is applied to reduce the Mn substance to Mn, and preferably thereafter the oxygen-containing acidity is set to dissolve the raw materials into a Co substance, and the oxygen-containing acidity is adjusted to precipitate the Co substance as a Co oxide, and preferably thereafter a potential is applied to reduce the Ni substance to Ni.

[0173] In one embodiment, the dissolution is carried out partially by electrochemical reduction dissolution.

[0174] In one embodiment, the dissolution is not carried out completely or partially by electrochemical dissolution.

[0175] In one embodiment, the potential of the molten salt is set by using an oxidizing-reducing agent to set the potential and / or by applying a voltage between the anode and the cathode in the molten salt to set the potential, and the step of setting the potential is carried out after the raw materials are contacted with the molten salt.

[0176] In one embodiment, the potential of the molten salt is set by using an oxidizing-reducing agent to set the potential or by applying a voltage between the anode and the cathode in the molten salt to set the potential, and the step of setting the potential is carried out after the raw materials are contacted with the molten salt.

[0177] In one embodiment, the oxidizing-reducing agent is selected from the following list: H2; alkali metals such as Mg, Be, and Ca; alkali metals, O2.

[0178] In one embodiment, the potential of the molten salt is set by using an oxidizing-reducing agent to set the potential, and the oxidizing-reducing agent is a gas containing H2 that is contacted with the molten salt.

[0179] The gas containing H2 may contain 1-20 vol.% H2, such as 2-17 vol.% H2, such as 3-15 vol.% H2, such as 4-10 vol.% H2, and the rest is an inert gas such as Ar or N2.

[0180] In one embodiment, the potential of the molten salt is set by setting the potential using an oxidation-reduction agent (a gas containing H2 in contact with the molten salt), and the potential is reduced by a voltage within the range of 0.05 to 0.75 V, such as within the range of 0.10 to 0.4 V, such as within the range of 0.15 to 0.3 V.

[0181] The molten salt may have a redox potential after contact with the raw material where there are more than one metal species of the same metal for the same oxygen acidity value. In this case, the redox material can be set to distinguish between one or more other metal species of the same metal present in the molten salt. For example, a higher redox potential value can favor the presence of a phase with a higher degree of oxidation relative to a phase with a lower degree of oxidation of the metal species.

[0182] In one embodiment, the oxygen acidity and the redox potential are set such that there is substantially one phase of the metal species.

[0183] In one embodiment, the oxygen acidity and the redox potential are set such that there are two phases of the metal species.

[0184] Depending on the purpose of metal species recovery, the presence of two different metal species of the same metal can be intentionally targeted.

[0185] The recovery of two metal species of the same metal, where one of these species forms a minor component of the recovered composite metal species, can form the basis for a raw material for a further metal / metal oxide recovery process. The advantage is that the raw material contains only very few substances for further processing with the simple process of the present invention.

[0186] In one embodiment, the concentration of one or more dissolved metal species is in the range of 0.1 to 10 mol / kg of molten salt, such as 0.2 to 7 mol / kg of molten salt, such as 0.4 to 5 mol / kg of molten salt, such as 0.8 to 3 mol / kg of molten salt.

[0187] Applying a potential

[0188] In one embodiment, the application of a potential to recover a first metal species as a first metal or a first metal oxide is carried out in an electrodeposition process, which includes:

[0189] - Applying a potential to two or more electrodes immersed in a molten salt containing a metal hydroxide of the metal species,

[0190] - Depositing and recovering the first metal or the first metal oxide from the electrode forming the cathode.

[0191] In a two - electrode or multi - electrode system, a potential can be applied between electrodes immersed in a molten hydroxide solvent containing dissolved metal substances, enabling the deposition of one or more metal substances onto the cathode. This process is commonly referred to as electroplating, electrochemical deposition, or electrodeposition. The potential can be selected based on the target dissolved metal substance and / or the target electroplated material. The selection of the relevant potential is carried out through the calculation and subsequent verification of a thermodynamic diagram as described below. The selected potential is applied using equipment such as potentiostats and galvanostats.

[0192] In one embodiment, the oxygen - containing acidity during dissolution is set to dissolve Co compounds from the cathode material of waste lithium - ion battery materials, and a potential is applied to recover the Co compounds as metallic cobalt. The selection of the potential will depend on the oxygen - containing acidity, and an example range can be 0.5 - 1V.

[0193] In another embodiment, Mn compounds are dissolved from the cathode material of waste lithium - ion battery materials, and a potential is applied to electrodeposit the Mn compounds as oxides. For this, an example of the potential range can be 1.75 - 2.2V.

[0194] In an example where both Mn and Ni are dissolved from the cathode material of waste lithium - ion battery materials, this allows for the separation of the two elements based on the applied potential. For example, if the oxygen - containing acidity is properly adjusted, Ni substances can be first electrodeposited as Ni metal onto the cathode, then the cathode can be replaced, and a different potential can be applied to electrodeposit Mn substances as oxides, thus achieving selective separation. For this, example potential ranges can be first 1 - 1.4V and second 1.5 - 2V.

[0195] Changes in the oxygen - containing acidity or redox potential of the hydroxide melt can cause the dissolved metal substances to form non - ionic oxide complexes. These oxides have low solubility in the molten hydroxide, much lower than the ionic substances generated during the dissolution of the raw materials, thus causing them to form solids and precipitate from the melt as metal oxides.

[0196] Reference will be made below to Figure 2 a flowchart showing embodiments of the present invention.

[0197] The raw material is waste lithium - ion battery material, which contains at least three metal oxides, such as in the form of a combined oxide.

[0198] Identify the metal compounds in the raw material. This is shown in Figure 2 the flowchart by reference number (1).

[0199] The potential - versus - oxygen - containing - acidity diagram is obtained from the calculation of thermodynamic data and the equilibrium constants of all involved equilibrium reactions, one diagram for each metal compound and at Figure 2It is represented as (2) in []. Potential measurements were also carried out to establish the figure. In addition, a potential vs. oxygen acidity diagram of the metal hydroxide used was established. NaOH was selected in this embodiment.

[0200] Figure 2 The oxygen acidity diagram represented as (2) in [] provides an additional input (3) for the next step (4) of the process step predefined for recovering the desired metal substances.

[0201] If the aim is to recover three metal substances in their respective metallic states, the oxygen acidity is set / regulated to the value at which the first metal exists as the first metal ion in the potential vs. oxygen acidity diagram. For this criterion, there is a range of oxygen acidity values, and within this range, the value is selected at which the metal under discussion is the only metal present as metal ions. Thereafter, the first metal oxide is dissolved at this oxygen acidity value, as Figure 2 represented by (5) in []. The first metal is recovered from the dissolved first metal ions by electroplating, as Figure 2 represented by (6) in []. The process steps (5) and (6) are repeated for the second metal substance and then the third metal substance until all three metal substances are recovered in their respective metallic states.

[0202] System for recovering one or more metal substances

[0203] In one embodiment, a system preferably used in the above method for recovering one or more metal substances from raw materials (such as waste lithium-ion battery materials) includes:

[0204] - A container containing a molten salt of at least one metal hydroxide

[0205] - A reservoir containing water vapor, the reservoir communicating with the bottom section of the container, and the bottom section including an ejector

[0206] - Two or more electrodes in contact with the molten salt of at least one metal hydroxide.

[0207] The raw material can be any of the raw materials disclosed in the aspect of the present invention of the method for recovering one or more metal compounds from raw materials (such as waste lithium-ion battery materials).

[0208] In one embodiment, the raw material is waste lithium-ion battery materials.

[0209] In one embodiment, the features of the above method can be used for a system for recovering one or more metal substances from raw materials (such as waste lithium-ion battery materials).

[0210] The molten salt containing the metal hydroxide is preferably located in the container.

[0211] In one embodiment, the metal hydroxide is one or more hydroxides selected from the group consisting of NaOH, KOH, LiOH, and RbOH, such as NaOH.

[0212] The container can be made of any material, such as metal, metal alloy, ceramic material, or a combination thereof, and in this context, the material is referred to as the container material. The inner surface can be the surface of the container material, so the lining material is the container material, or the container material can be coated with an additional material to provide the lining material. For example, the container material can be a metal alloy, such as a nickel-based alloy, a nickel-based superalloy, or Hastelloy, or nickel. In this context, a nickel-based alloy is an alloy having at least 50 w.% nickel.

[0213] In one embodiment, the container contains polytetrafluoroethylene, such as a gasket of polytetrafluoroethylene.

[0214] In one embodiment, the container and / or the inner surface of the container contains a ceramic material.

[0215] The container can have any size and shape as needed. Exemplary container volumes are in the range of 1 m 3 to 10 m 3 .

[0216] In one embodiment, the container includes means for forced circulation of the molten salt.

[0217] When the molten salt of the metal hydroxide is in the container, the molten salt of the metal hydroxide can be stationary, or the molten salt of the metal hydroxide can circulate in the container by natural convection, forced convection, or forced circulation.

[0218] Generally, the means for forced circulation can be to stir the molten salt of the metal hydroxide. Any kind of stirring device can be used.

[0219] In this context, natural convection is considered to involve the movement occurring in the molten salt of the metal hydroxide due to the temperature and / or component concentration gradient of the molten salt of the metal hydroxide, without any active steps being taken to affect the convection. In this context, when no active steps are taken to create the temperature and / or concentration gradient, the molten salt of the metal hydroxide is generally considered to be stationary. In contrast, forced convection is considered to involve the movement in the molten salt of the metal hydroxide caused by the active introduction of a temperature and / or concentration (especially temperature) gradient.

[0220] In one embodiment, the container includes means for locally heating the molten salt.

[0221] Local heating of a certain volume of molten salt of metal hydroxide can cause local expansion of the molten salt of metal hydroxide near the heat source, which causes movement in the molten salt of metal hydroxide. Similarly, local cooling of a certain volume of molten salt of metal hydroxide can cause local contraction of the molten salt of metal hydroxide near the radiator, which causes movement in the molten salt of metal hydroxide. Forced convection and forced circulation make the oxygen acidity in the molten salt of metal hydroxide generally uniform. In this context, forced circulation can be represented by volume displacement over time and is in units of per hour (or h 1 ), for example, the volume displacement can be in 0.1h 1 to 100h 1 , for example 1h 1 to 20h 1 .

[0222] In one embodiment, the container contains a covering gas above the molten salt of metal hydroxide,

[0223] In one embodiment, the container has a lid covering the molten salt of metal hydroxide to provide a closed system.

[0224] The lid may also have an opening to control the composition and pressure of the covering gas. The covering gas can be maintained at a pressure higher than the ambient pressure, for example, at a pressure in the range of 1 bar to 10 bar.

[0225] The container includes heating means for heating the salt of metal hydroxide.

[0226] In one embodiment, the container includes a heating element and thermal insulation material to maintain a desired temperature in the container throughout the process of recovering one or more metal compounds.

[0227] The container may include a funnel at the upper section of the container to provide means for supplying raw materials to the molten salt of metal hydroxide.

[0228] In one embodiment, the system includes a cathode stock.

[0229] The system may also include a crane. The crane will lift one or more cathodes with electrodeposited metal substances from the molten salt after electrodeposition and lift cathodes from the unused cathode stock into the molten salt.

[0230] The system includes a reservoir containing water vapor, which communicates with the bottom section of the container.

[0231] The purpose of the reservoir is to prepare and supply a processing gas containing an oxygen acidity agent (such as water vapor).

[0232] In one embodiment, the reservoir includes a container containing water. The water can be heated by a thermal jacket controlled by a temperature transmitter.

[0233] In one embodiment, the system includes an injector, which is preferably included in the bottom section of the container.

[0234] The injector provides a means for supplying water vapor from the reservoir to the molten salt of the metal hydroxide. The means can be an inlet hole through which a gas (such as a process gas containing water vapor) bubbles through the molten salt.

[0235] The use of the injector ensures the mixing of the raw materials in the molten salt and a consistent oxygen acidity value throughout the molten salt.

[0236] In one embodiment, the injector is adapted to inject a gas containing an oxygen acidity agent (such as water vapor).

[0237] The gas can contain, for example, water vapor as the oxygen acidity agent at a partial pressure in the range of 0.01 bar to 2 bar, such as 0.02 bar to 0.5 bar.

[0238] In one embodiment, the injector is adapted to inject a gas containing an oxidation-reduction agent.

[0239] In one embodiment, the process gas contains an oxidation-reduction agent, such as H2.

[0240] In one embodiment, the system includes an exhaust gas system, which includes an exhaust gas pipeline between the container and the reservoir. The exhaust gas pipeline removes the injected gas from the container and transports it to the reservoir.

[0241] In one embodiment, the exhaust gas system includes means for controlling the pressure in the container.

[0242] In one embodiment, the process gas introduced into the reservoir can be fed from the exhaust gas system.

[0243] In one embodiment, inlet and outlet humidity transmitters are provided on the gas pipeline, such as the exhaust gas pipeline for entering and leaving the container.

[0244] In one embodiment, the pressure reservoir is in communication with the exhaust gas pipeline.

[0245] The pressure reservoir will provide a backup in case of flow losses from the container to the reservoir.

[0246] An oxygen-containing acidity agent (such as water vapor) is recycled from the container to the reservoir, and the content of the oxygen-containing acidity agent can be replenished in the process gas. The replenishment can be carried out by providing water or water vapor. For example, the oxygen-containing acidity agent can be directly added to the process gas, and then it can be bubbled through the molten salt of metal hydroxide by means of an ejector. By using a process gas containing an oxygen-containing acidity agent and bubbling the process gas through the molten salt of metal hydroxide to recycle the process gas, a setting is produced in which the oxygen acidity of the molten salt of metal hydroxide is easily controlled.

[0247] On the inlet and outlet gas pipelines leading to the container, humidity transmitters may be present to feed the control system in the reservoir.

[0248] In one embodiment, the system includes a salt disposal system.

[0249] The purpose of the salt disposal system is to prepare the salt before it enters the container. One or more salts of metal hydroxide are supplied to the salt disposal system and the salt is melted and transferred to the container. The salt disposal system includes heating elements, thermal insulation materials, and may include one or more temperature transmitters and controllers for regulating the temperature of the molten salt.

[0250] The salt disposal system can provide means for receiving the molten salt from the container. The salt disposal system can provide means for storing the molten salt, such as storing the salt at the end of the process of recovering one or more metal substances.

[0251] In one embodiment, two or more electrodes are brought into contact with the molten salt of at least one metal hydroxide in the container.

[0252] In one embodiment, the reservoir contains a covering gas above the molten salt of metal hydroxide,

[0253] In one embodiment, the container may have a lid covering the molten salt of metal hydroxide to provide a closed system.

[0254] The lid may also have an opening to control the composition and pressure of the covering gas. The covering gas can be maintained at a pressure higher than the ambient pressure, for example, at a pressure in the range of 1 bar to 10 bar.

[0255] In one embodiment, a reservoir is provided for the use of recovering at least one metal and / or at least one metal oxide from a metal compound, the reservoir containing one or more oxygen-containing acidity agents and being in communication with a molten salt containing at least one metal hydroxide and a raw material containing the metal compound. Description of the Drawings

[0256] In the following, the present invention will be described in more detail with the help of examples and with reference to the schematic drawings, in which Figure 1aShows the superposition of the oxyacid diagrams of Mn and NaOH;

[0257] Figure 1b Shows the superposition of the oxyacid diagrams of Ni and NaOH; Figure 1c Shows the superposition of the oxyacid diagrams of Co and NaOH.

[0258] Figure 2 Shows the flowchart demonstrating the embodiments of the present invention.

[0259] Figure 3 Shows the system for carrying out the embodiments of the method according to the present invention.

[0260] Figure 4a Shows the cyclic voltammogram of Co.

[0261] Figure 4b Shows the cyclic voltammogram of Co.

[0262] Figure 5 Shows two cyclic voltammograms of Co recorded on Ni at two different oxyacidities

[0263] Figure 6 Shows the SEM of the deposited Co.

[0264] Figure 7 Shows the SEM of the deposited MnO.

[0265] Figure 8 Shows the SEM of the deposited NiCoO.

[0266] Figure 9 Shows the SEM of the deposited NiCoMnO

[0267] Figure 10 Shows the cyclic voltammogram of NMC in molten NaOH, wet atmosphere;

[0268] Figure 11 Shows the cyclic voltammogram of Ni;

[0269] Figure 12 Shows the SEM of the deposited Ni;

[0270] Figure 13 Shows the changes in open circuit potential and nickel concentration;

[0271] Figure 14 Shows the superposition of the oxyacid diagrams of Fe and NaOH;

[0272] Figure 15 Shows the cyclic voltammogram of Fe;

[0273] Figure 16Shows the changes in open circuit potential and iron concentration.

[0274] The present invention is not limited to one or more embodiments shown in the drawings. Thus, it should be understood that when a feature recited in the appended claims is followed by a reference numeral, such a numeral is included solely for the purpose of enhancing the intelligibility of the claim and in no way limits the scope of the claim.

[0275] As used in this specification and the claims, the term "comprising" means "consisting at least in part of". When interpreting a statement in this specification and the claims that includes the term "comprising", there may be other features in addition to the features recited at the beginning of each statement. Related terms such as "comprises" and "comprising" should be interpreted in a similar manner. Detailed Description

[0277] The method will now be illustrated in the following non - limiting examples.

[0278] A system (1) for recovering one or more metal compounds is shown in Figure 3 . The system (1) includes a container (2) having a liner material of ceramic material. The container (2) contains a molten salt (3) of NaOH or another metal hydroxide. The container (2) communicates with a salt disposal system (not shown) for preparing salts, for example. A cathode (4) is partially immersed in the molten salt, and the cathode (4) forms part of an electrodeposition arrangement (not shown) that includes one or more other electrodes for electrodeposition. After electrodeposition, the cathode (4) can be replaced with another cathode from a cathode stock (5). The replacement of the cathode can be carried out with a crane (6) that lifts the cathode with the electrodeposited metal compound from the molten salt after electrodeposition and lowers a cathode from the stock into the molten salt. Raw materials containing the metal compounds to be recovered are provided to the molten salt (3) via a funnel (7).

[0279] The bottom section (8) of the container (2) is provided with an ejector (not shown), and the ejector interfaces with a reservoir (9) for humidifying the carrier gas. The reservoir (9) contains water (10) and water vapor (11), and is provided with a heating jacket for heating the water. The water vapor is directed through a pipe outlet to the ejector in the bottom section of the container. During the processing of the raw materials, when water vapor is drawn from the reservoir to the container, a water inlet (12) in communication with the reservoir replenishes the reservoir with water.

[0280] The exhaust gas from the upper section of the container (3) is directed via an exhaust gas line (13) to the reservoir (9).

[0281] Example 1

[0282] In this example, the recovery of metallic Co is shown. The material selected for the recovery of Co from which is cobalt oxide with a purity of 99.8% supplied by Sigma-Aldrich. The hydroxide used in this process is NaOH with a purity higher than 98% supplied by Fisher Scientific

[0283] The "equilibrium redox potential vs. oxygenated acidity" diagram is calculated from thermodynamic data and is presented in Figure 1c as "E vs. pa(H2O)". This diagram represents the behavior of Co and its oxides in the molten salt of NaOH at 500 °C

[0284] For molten sodium hydroxide at 500 °C, the calculated thermodynamic diagram of cobalt is shown in Figure 1C. The dashed line represents the calculated thermodynamic diagram of molten sodium hydroxide

[0285] After establishing the Figure 1c calculated diagrams in, several electrochemical measurements were carried out to verify these diagrams. The electrochemical measurements also allowed obtaining parameter information for additional process steps for the recovery of Co. The electrochemical measurements are further explained below

[0286] Recovery of Co

[0287] A 150 g of sodium hydroxide (pellets) was filled in an alumina crucible. Then, the crucible was placed in a reaction cell consisting of an Inconel 600 container (bottom) and a borosilicate lid (top). The NaOH was melted and maintained at a temperature of 500 °C. The system was always kept in an argon atmosphere

[0288] The sodium hydroxide in the crucible was connected to a water vapor reservoir for supplying water vapor to the hydroxide to adjust the oxygenated acidity of the hydroxide. The humidity of the covering gas determines the value of the oxygenated acidity in the hydroxide

[0289] The target oxygenated acidity was determined by the following electrochemical measurements. Three cyclic voltammograms (CVs) were recorded, one cyclic voltammogram for each oxygenated acidity value, which reflects three temperatures of a water bath heating the oxygenated acidity agent H2O, and the temperatures of the water bath were 35 °C, 60 °C, and 80 °C. The difference in the water bath temperature affects the difference in humidity and thus affects the content of the oxygenated acidity agent H2O. The three CVs are shown in Figure 4a in

[0290] Figure 4 shows cyclic voltammograms recorded in molten sodium hydroxide in the presence of CoO in a wet ( Figure 4a ) and dry ( Figure 4b ) argon covering atmosphere at 500 °C

[0291] The humidity is based on Figure 4aThe CV in [reference] is selected. It is decided to adjust the oxygenated acidity to a value based on Co dissolution, which shows a significant peak at approximately -1.4 V relative to the Pt reference. Other relevant chemical reactions that occur during CV in a dry argon atmosphere are shown in Figure 4b and are denoted as A1, A2, C1, and C2. Some of these reactions are also shown in Figure 4a for three CVs with water vapor (wet argon atmosphere), one CV corresponding to each value of the temperature of the oxygenated acidity agent H2O (water bath) at 35 °C, 60 °C, and 80 °C.

[0292] The cyclic voltammogram in Figure 4 was recorded using a Pt working electrode in NaOH in the presence of CoO. The scan rate was 100 mV / s, and the temperature of NaOH was 500 °C.

[0293] The oxygenated acidity of NaOH was adjusted by supplying H2O from a reservoir at a water bath temperature of 80 °C to provide the target oxygenated acidity conditions.

[0294] 2.18 g of powdered CoO was brought into contact with molten NaOH at 500 °C and held at this temperature for 1 day. The concentration of CoO in NaOH was 0.194 mol / kg NaOH.

[0295] Thereafter, electrolysis was carried out for 1 hour (Q = 510.16 C) by applying a cathodic potential of -1.22 V relative to Pt in order to electroplate Co from the melt into its metallic form. A nickel-201 coupon was used as the substrate for electroplating in molten NaOH at 500 °C using a wet argon covering atmosphere. The temperature of the water bath was 80 °C.

[0296] The electrode potential value of -1.22 V relative to Pt was found from the voltammogram recorded in molten NaOH salt on a nickel 201 working electrode (coupon) at 500 °C. The CV is shown in Figure 5 and was carried out before each electroplating process. The scan rate was 100 mV / s. Two different oxygenated acidity conditions, represented by water bath temperatures fixed at 25 °C and 80 °C respectively, were used.

[0297] Figure 5 Shows the cyclic voltammogram recorded in molten NaOH in the presence of CoO at 500 °C in a wet argon covering atmosphere.

[0298] For Figure 6 Energy-dispersive x-ray spectroscopy (EDS) was carried out on the electroplated Co in the portion shown in the scanning electron micrograph (SEM) of the electrode surface magnified 880 times in [reference] to determine the elements present.

[0299] The results of EDS are shown in Table 1.

[0300] Table 1

[0301]

[0302] It was found that the wt.% of the recovered metallic cobalt was 97.7%.

[0303] Example 2

[0304] In this example, the recovery of several oxides was shown. The material selected was LiNi with a purity of 98% supplied by Sigma-Aldrich 0.33 Mn 0.33 Co 0.33 O2 (lithium nickel manganese cobalt oxide, NMC). The hydroxide used in this process was NaOH with a purity higher than 98% supplied by Thermo Fisher Scientific

[0305] The "equilibrium redox potential vs. oxygen acidity" diagram calculated from the thermodynamic data used was a diagram of individual oxides, such as the Co oxide diagram, the Ni oxide diagram.

[0306] Several electrochemical measurements were carried out to verify the diagram. The electrochemical measurements also allowed obtaining parameter information for additional process steps for the recovery of Co. The electrochemical measurements are further explained below.

[0307] Recovery of MnO

[0308] A 150 g of sodium hydroxide (pellets) was filled in an alumina crucible. Then, the crucible was placed in a reaction cell composed of an Inconel 600 container (bottom) and a borosilicate lid (top). The NaOH was melted and maintained at a temperature of 500 °C. The system was always kept in an argon atmosphere.

[0309] The sodium hydroxide in the crucible was connected to a water vapor reservoir for supplying water vapor to the hydroxide to adjust the oxygen acidity of the hydroxide. The humidity of the covering gas determined the value of the oxygen acidity in the hydroxide.

[0310] The cyclic voltammogram (CV) at a water bath temperature of 80 °C was recorded. The CV is shown in Figure 10 .

[0311] It was decided to adjust the oxygen acidity to a value based on the Co dissolution, which showed a significant peak at about -1.4 V relative to the Pt reference. Other relevant chemical reactions occurring during the CV in a dry argon atmosphere are shown in Figure 10 .

[0312] Figure 10 The cyclic voltammogram in 0.33 Mn 0.33 Co 0.33Recorded with a Pt working electrode in the presence of O2. The scan rate was 100 mV / s, and the temperature of NaOH was 500 °C.

[0313] The oxygen acidity of NaOH was adjusted by supplying H2O from a reservoir at a water bath temperature of 80 °C to provide the target oxygen acidity condition.

[0314] 2.56 g of LiNi supplied as a powder 0.33 Mn 0.33 Co 0.33 O2 was contacted with molten NaOH at 500 °C and held at this temperature for 1 day. LiNi 0.33 Mn 0.33 Co 0.33 The concentration of O2 in NaOH was 0.199 mol / kg NaOH.

[0315] Thereafter, electrolysis was carried out for 1 hour (Q = 128.43 C) by applying a cathodic potential of -1.05 V relative to Pt in order to electroplate MnO from the melt. A nickel-201 specimen was used as the substrate for electroplating in molten NaOH under a dry argon blanket atmosphere at 500 °C.

[0316] The electrode potential value of -1.05 V relative to Pt was found from the voltammogram recorded in molten NaOH salt on a nickel 201 working electrode (wire, 0.33 cm 2 surface area exposed to the salt). The CV is shown in Figure 10 and was carried out before each electroplating process. The scan rate was 100 mV / s.

[0317] Figure 10 Shows the cyclic voltammogram recorded in molten NaOH in the presence of LiNi 0.33 Mn 0.33 Co 0.33 O2 under a wet argon blanket atmosphere at 500 °C.

[0318] For Figure 7 Energy dispersive x-ray spectroscopy (EDS) was performed on the electroplated MnO in the portion shown in the scanning electron micrograph (SEM) of the electrode surface magnified 570 times in

[0319] to determine the elements present. The results of the EDS are shown in Table 2

[0320] Table 2.

[0321]

[0322] Na was visible in the EDS and was most likely due to incomplete washing of the NaOH before analysis.

[0323] It was found that the wt.% of the recovered MnO was approximately 70%.

[0324] Recovery of CoNiO

[0325] In this example, the recovery of CoNiO is shown.

[0326] Example 2 used the same conditions except for the following electrolysis conditions.

[0327] Electrolysis was carried out for 1 hour (Q = 0.532 C) by applying a cathodic potential of -0.05 V relative to Pt in order to electroplate CoNiO from the melt. Nickel-201 (wire, 0.33 cm 2 surface area exposed to the salt) was used as the substrate for electroplating in molten NaOH at 500 °C under a dry argon blanket atmosphere.

[0328] The electrode potential value of -0.05 V relative to Pt was found from the voltammogram for MnO as described above.

[0329] For Figure 8 Energy-dispersive X-ray spectroscopy (EDS) was performed on the electroplated Co in the portion shown in the scanning electron micrograph (SEM) of the electrode surface magnified 2550 times in

[0330] The results of the EDS are shown in Table 3.

[0331] Table 3.

[0332]

[0333] The wt.% of the recovered CoNiO was equivalent to approximately 83 wt.%

[0334] Recovery of CoNiMnO

[0335] In this example, the recovery of CoNiMnO is shown.

[0336] Example 2 used the same conditions except for the following electrolysis conditions.

[0337] Thereafter, electrolysis was carried out for 1 hour (Q = 66.56 C) by applying a cathodic potential of -1.38 V relative to Pt in order to electroplate CoNiO from the melt. Nickel-201 (wire, 0.33 cm 2 surface area exposed to the salt) was used as the substrate for electroplating in molten NaOH at 500 °C under a wet argon blanket atmosphere. The temperature of the water bath was 80 °C.

[0338] The electrode potential value of -1.38 V relative to Pt was found from the voltammogram for MnO as described above.

[0339] For Figure 9 Energy-dispersive X-ray spectroscopy (EDS) was performed on the electroplated Co of the portion shown in the scanning electron micrograph (SEM) of the electrode surface magnified 570 times in

[0340] to determine the elements present. The results of the EDS are shown in Table 4.

[0341] Table 4.

[0342]

[0343]

[0344] The wt.% of the recovered CoNiMnO is approximately 99.0 wt.%.

[0345] Example 3

[0346] In this example, the recovery of metallic Ni is shown. The material selected for the recovery of Ni from it is NiO with a purity of 97% supplied by Acros Organics. The hydroxide used in this process is NaOH with a purity higher than 98% supplied by Thermo Fisher Scientific.

[0347] The plot of "equilibrium redox potential vs. oxygen acidity" for Ni calculated from thermodynamic data is shown in Figure 1b .

[0348] This plot represents the behavior of Ni and the oxide in the molten salt of NaOH at 500 °C and is used as a guide to determine the values of the equilibrium redox potential and oxygen acidity values at 600 °C (where recovery occurs).

[0349] For molten sodium hydroxide at 500 °C, the calculated thermodynamic plot for Ni is shown in Figure 1b . The dashed line represents the calculated thermodynamic plot of molten sodium hydroxide.

[0350] After establishing the Figure 1b calculated plots in , several electrochemical measurements were carried out to verify these plots. The electrochemical measurements also allowed obtaining parameter information for additional process steps for the recovery of Ni.

[0351] Recovery of Ni

[0352] 120 ± 1 g (about 3 mol) of ≥98% pure sodium hydroxide pellets were placed inside an alumina crucible. The crucible was inserted into the cell, and the argon inlet and scrubber system outlet were inserted into the cell, and the flow was turned on. After a stepwise heating procedure, the temperature of the melt was (600 ± 15) °C.

[0353] After dissolving 2.263 g of NiO in the melt for 24 hours, the OCP (open circuit potential) value stabilizes to a value of 0.976 V relative to the SRE (standard sodium electrode, Na / Na+), while the estimated oxygen acidity is pH2O = 6.

[0354] After the electrochemical measurements, the argon gas was replaced with a hydrogenated covering atmosphere (5 vol.% H2 - 95% Ar mixture), and after 50 minutes the OCP dropped to a stable value of 0.834 V. After 1 hour of hydrogen exposure (stage H2(1h)), CV measurements were performed with a wire electrode set, the results of which are given in Figure 11 below.

[0355] The complete absence of reduction peaks associated with the presence of oxidized Ni species indicates a substantial lack of oxidized species in the immediate vicinity of the working electrode, and suggests that the hydrogenated atmosphere reduces the Ni species to its metallic form. In fact, SEM / EDS analysis of the slurry sample taken after 1 hour of hydrogen exposure shows that small particles of metallic nickel have precipitated at the bottom of the crucible, see Figure 12 .

[0356] The variations of the OCP and the nickel concentration in the melt with respect to the experimental stages are shown in Figure 13 below.

[0357] Energy-dispersive X-ray spectroscopy (EDS) was performed on the precipitate shown in the scanning electron micrographs to determine the elements present.

[0358] The results of the EDS are shown in Table 5.

[0359] Table 5

[0360]

[0361] It was found that the wt.% of the recovered metallic nickel was 99.5%.

[0362] Example 4

[0363] In this example, the recovery of metallic Fe is shown. The material selected from which to recover Fe is iron(III) oxide (Fe2O3) with a purity of 96% as supplied by Acros Organics. The hydroxide used in this process is NaOH with a purity higher than 98% supplied by Thermo Fisher Scientific.

[0364] The thermodynamic diagram used was calculated from the values of Fe in NaOH at 500 °C obtained from HSC 10.0, see Figure 14 .

[0365] This figure can be used to understand the behavior of Fe and oxides in the molten salt of NaOH and serves as a guide for determining the equilibrium redox potential value and the oxygen-containing acidity value at 600 °C (where recovery occurs).

[0366] For molten sodium hydroxide at 500 °C, the calculated thermodynamic diagram of Fe is shown in Figure 14 . The dashed line represents the calculated thermodynamic diagram of molten sodium hydroxide.

[0367] After establishing the calculation diagram in Figure 14 , several electrochemical measurements were carried out to verify the diagram. The electrochemical measurements also allowed obtaining parameter information for additional process steps for Fe recovery.

[0368] Recovery of Fe

[0369] 120 ± 1 g (about 3 mol) of ≥98% pure sodium hydroxide pellets were placed in an alumina crucible. The crucible was inserted into the cell, and the argon inlet and scrubber system outlet were inserted into the cell, and the flow was turned on. After a stepwise heating procedure, the temperature of the melt was (600 ± 15) °C.

[0370] After dissolving 2.374 g of Fe2O3 in the melt for 24 hours, the OCP (open circuit potential) value stabilized at 0.887 V relative to the SRE (standard sodium electrode, Na / Na+), while the estimated oxygen-containing acidity was pH2O = 4.5.

[0371] After the electrochemical measurements were carried out, the argon was replaced with a hydrogenated cover gas (5% H2 - 95% Ar mixture). After applying the hydrogenated atmosphere to the system, the OCP experienced the sharpest drop within the first hour, reaching a value of 0.715 V, after which the OCP experienced a slow progressive reduction in the OCP, reaching 0.682 V at the 24-hour mark.

[0372] After 1 hour of hydrogen exposure (stage H2(1h)), CV measurements were carried out with a wire electrode set, and the results are given in Figure 15 .

[0373] The R1 peak from the CV in Figure 15 has been identified in the CV measurements as the reaction: R1: Fe(III) + 3e - → Fe.

[0374] The variations of the OCP and the iron concentration in the melt with respect to the experimental stages are shown in Figure 16 .

[0375] The R1 peak (attributed to the reduction of Fe(III) to Fe(0)) appears at a potential of approximately 0.5 V, where its onset is at approximately 0.6 V. Using a H2 pressure value greater than that provided by a hydrogenated cover gas atmosphere (a 5% H2 - 95% Ar mixture) will result in a shift of the OCP to a potential of, for example, a value of 0.5 V and will result in the recovery of Fe.

[0376] Such a H2 pressure value provided by a hydrogenated cover gas atmosphere is, for example, a 10% H2 - 90% Ar mixture.

[0377] In addition, increasing the oxygen acidity of the melt would be beneficial as a higher water content would shift the metallic iron stability window to a higher potential, and thus a wet hydrogenated cover gas atmosphere would result in the recovery of metallic iron (Fe(0)) at the same potential compared to a dry hydrogen atmosphere.

Claims

1. A method for recovering one or more metal substances from raw materials such as waste lithium-ion battery materials, the method comprising: - Providing a molten salt containing at least one metal hydroxide - Providing one or more oxygen-containing acidity agents, preferably as reservoirs of one or more oxygen-containing acidity agents in communication with the molten salt a) Setting the oxygen-containing acidity of the molten salt with the one or more oxygen-containing acidity agents to an oxygen-containing acidity value at which at least one metal substance dissolves in the molten salt - Contacting the raw material with the molten salt - Performing at least one of steps b) and c): b) Setting the potential of the molten salt to recover a first metal substance as a first metal or a first metal oxide, c) Adjusting the oxygen-containing acidity of the molten salt with the one or more oxygen-containing acidity agents to precipitate a first metal oxide, d) Optionally, for one or more additional metal substances, performing method step a) and / or performing at least one of these method steps b) and c).

2. The method according to claim 1, wherein The potential of the molten salt is set by setting the potential using an oxidizing-reducing agent and / or by setting the potential by applying a voltage between an anode and a cathode in the molten salt, and the step of setting the potential is performed after contacting the raw material with the molten salt.

3. The method according to any one of claims 1 or 2, wherein The potential of the molten salt is set by setting the potential using an oxidizing-reducing agent, which is a gas containing H2 in contact with the molten salt.

4. The method according to claim 3, wherein, The potential decreases by a voltage in the range of 0.05 to 0.75V.

5. The method according to claim 3, wherein The potential decreases by a voltage in the range of 0.10 to 0.4V.

6. The method according to claim 3, wherein, The potential decreases by a voltage in the range of 0.15 to 0.3V.

7. The method according to any one of the preceding claims, wherein, The raw material contains a metal oxide complex.

8. The method according to any one of the preceding claims, wherein, The raw material contains a metal Co oxide complex.

9. The method according to any one of the preceding claims, wherein, Setting the oxygen-containing acidity to dissolve the raw material into a first metal substance; applying a potential to reduce the first metal substance to a first metal, and thereafter setting the oxygen-containing acidity to dissolve the raw material into a second metal substance; Applying a potential to reduce the second metal substance to a second metal, and preferably thereafter setting the oxygen-containing acidity to dissolve the raw material into a third metal substance; applying a potential to reduce the third metal substance to a third metal.

10. The method according to claim 9, wherein, The first metal is Mn, and the one or more additional metals are selected from the group consisting of Al and transition metals.

11. The method according to claim 10, wherein, The one or more additional metals are selected from the group consisting of Al and Fe, Co, and Ni.

12. The method according to any one of claims 1 to 8, wherein Setting the oxygen-containing acidity to dissolve the first, second, and third metal substances, Adjusting the oxygen-containing acidity to precipitate the first metal substance as a first metal oxide, preferably thereafter adjusting the oxygen-containing acidity to precipitate the second metal substance as a second metal oxide, and preferably thereafter adjusting the oxygen-containing acidity to precipitate the third metal substance as a third metal oxide.

13. The method according to claim 12, wherein, The first metal substance is a Co substance, and the one or more additional metal substances are transition metal substances.

14. The method according to claim 13, wherein, The one or more additional metal substances are transition metal substances selected from the group consisting of Fe, Mn, and Ni.

15. The method according to any one of the preceding claims, wherein, Applying the potential to recover the first metal substance as a first metal or a first metal oxide is performed in an electrodeposition process, the electrodeposition process comprising: - Apply this potential to two or more electrodes immersed in this molten salt containing the metal hydroxides of these metal substances, - Deposit the first metal or the first metal oxide and recover it from the electrode forming the cathode.

16. The method according to any one of the preceding claims, wherein, The oxygen-containing acidity agent is a compound of one or more groups selected from OH - , O 2- and H2O.

17. The method according to any one of the above claims, wherein, The metal hydroxide is one or more hydroxides selected from the group consisting of NaOH, KOH, LiOH, and RbOH.

18. The method according to any one of the preceding claims, wherein The raw material is waste lithium-ion battery material containing electrode material.

19. The method according to any one of the preceding claims, wherein The raw material is waste lithium-ion battery material containing cathode material.

20. The method according to any one of the preceding claims, wherein, The raw material includes one or more waste lithium-ion battery materials, and these waste lithium-ion battery materials are based on oxides selected from the group consisting of: Lithium nickel manganese cobalt oxide (NMC, LiNi x Mn y Co z O2), Lithium nickel cobalt aluminum oxide (NCA, LiNiCoAlO2), Lithium manganese oxide (LMO, LiMn2O4), Lithium iron phosphate (LFP, LiFePO4), Lithium cobalt oxide (LCO, LiCoO2).

21. The method according to any one of the preceding claims, wherein, The concentration of the dissolved one or more metal substances is in the range of 0.1 to 10 mol / kg of the molten salt.

22. The method according to any one of the preceding claims, wherein The concentration of the dissolved one or more metal substances is in the range of 0.2 to 7 mol / kg of the molten salt.

23. The method according to any one of the above claims, wherein The concentration of the dissolved one or more metal substances is in the range of 0.4 to 5 mol / kg of the molten salt.

24. The method according to any one of the above claims, wherein, The concentration of the dissolved one or more metal substances is in the range of 0.8 to 3 mol / kg of the molten salt.

25. A system for recovering one or more metal substances from a raw material, the system comprising: - A container of molten salt containing at least one metal hydroxide - A reservoir containing water vapor, the reservoir communicating with the bottom section of the container, and the bottom section including an ejector - Two or more electrodes in contact with the molten salt of the at least one metal hydroxide.

26. The system according to claim 25, wherein, The system is used in the method according to any one of claims 1-24.

27. The system according to claim 25 or 26, wherein The raw material is waste lithium-ion battery material.

28. The system according to any one of claims 25-27, which includes a cathode inventory.

29. The system according to any one of claims 25-28, wherein, The ejector is adapted to eject a gas containing an oxidation-reducing agent.

30. The system according to claim 29, wherein The oxidation-reducing agent is H2.

31. The system according to any one of claims 25 - 30, wherein, The molten salt contains a material that promotes the recovery of the precipitation of these metal substances on the surface.

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