Recovery method for recovering cobalt and nickel

Abstract

To provide a recovery method that can recover cobalt and nickel from raw material powders containing cobalt, nickel, and copper with high efficiency while suppressing the inclusion of copper. [Solution] A recovery method for recovering cobalt and nickel from raw material powder containing cobalt, nickel, and copper, comprising: a slurrying step of mixing the raw material powder containing cobalt, nickel, and copper with water and phosphoric acid to obtain a slurry; an acid leaching step of mixing the slurry obtained in the slurrying step with an acid and an oxidizing agent to obtain an acid leaching solution; and a neutralization step of adding alkali to the acid leaching solution obtained in the acid leaching step.

Description

Technical Field

[0001] The present invention relates to a recovery method for recovering cobalt and nickel from raw material powder containing cobalt, nickel, and copper.

Background Art

[0002] Since lithium-ion secondary batteries and the like contain valuable substances such as cobalt and nickel, in recent years, attention has been paid to recycling these valuable substances from the powder obtained by crushing and incinerating lithium-ion secondary batteries and the like.

[0003] Patent Document 1 describes a method for recovering metals from lithium-ion battery waste, which includes a wet treatment of leaching the metals in the lithium-ion battery waste with an acid and extracting the metals from the metal-containing solution in which the metals are dissolved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a result of the present inventors studying a recovery method for recovering cobalt and nickel from raw material powder containing cobalt, nickel, and copper using the method described in Patent Document 1, it became clear that the leaching of cobalt and nickel with an acid is insufficient in the method described in Patent Document 1. Therefore, as a result of intensive studies by the present inventors, it was successful in promoting the leaching of cobalt and nickel by using an oxidizing agent in addition to an acid during leaching with an acid.

[0006] However, it became clear that when acid leaching is performed using an acid and an oxidizing agent, the leaching of impurity metals such as copper is also promoted in addition to cobalt and nickel. Therefore, after further intensive research by the inventors, they discovered that by mixing raw material powders containing cobalt, nickel, and copper with water and phosphoric acid to form a slurry before acid leaching using acid and an oxidizing agent, the recovery rate of cobalt and nickel can be kept high while the contamination of copper can be reduced, thus completing the present invention.

[0007] The present invention aims to solve the aforementioned problems in the conventional approach and achieve the following objectives. Specifically, the present invention aims to provide a recovery method that can recover cobalt and nickel from raw material powder containing cobalt, nickel, and copper with high efficiency while suppressing the inclusion of copper. [Means for solving the problem]

[0008] As a result of diligent research conducted by the present inventors to achieve the above objective, they have found that it is possible to provide a recovery method that can recover cobalt and nickel from raw material powder containing cobalt, nickel, and copper with high efficiency while suppressing the inclusion of copper.

[0009] The present invention is based on the aforementioned findings by the inventors, and the means for solving the aforementioned problems are as follows: <1> A recovery method for recovering cobalt and nickel from raw material powder containing cobalt, nickel, and copper, A slurrying step involves mixing raw material powders containing cobalt, nickel, and copper with water and phosphoric acid to obtain a slurry. An acid leaching step is performed in which the slurry obtained in the slurry formation step is mixed with an acid and an oxidizing agent to obtain an acid leaching solution. A neutralization step is performed by adding alkali to the acid leaching solution obtained in the acid leaching step, This recovery method is characterized by including [a specific component]. <2> The raw material powder containing cobalt, nickel, and copper is a heat-treated product of a lithium-ion secondary battery. <1> This is the collection method described in [the relevant document]. <3> The raw material powder containing cobalt, nickel, and copper is a magnetic material obtained by classifying and wet magnetic separation of a heat-treated lithium-ion secondary battery. <1> This is the collection method described in [the relevant document]. <4> In the slurrying step, phosphoric acid is added in an amount of 0.05 molar equivalents or more and 1.2 molar equivalents or less relative to the total molar amount of impurity metals other than valuable metals, including cobalt and nickel, in the raw material powder. <1> from <3> The collection method is one of the methods described in either of the following. <5> In the slurrying step, phosphoric acid is added in an amount of 0.4 molar equivalents or more and 1.2 molar equivalents or less relative to the total molar amount of impurity metals other than valuable metals, including cobalt and nickel, in the raw material powder. <1> from <3> The collection method is one of the methods described in either of the following. <6> The acid leaching process is carried out under the conditions that the pH is 1.0 or higher and 3.0 or lower, and the oxidation-reduction potential measured with respect to a silver-silver chloride electrode is -250mV or higher and 0mV or lower. <1> from <3> The collection method is one of the methods described in either of the following. <7> The neutralization step is performed under the conditions that the pH is 3.0 or higher and 5.0 or lower, and the oxidation-reduction potential measured with respect to a silver-silver chloride electrode is 300mV or higher and 550mV or lower. <1> from <3> The collection method is one of the methods described in either of the following. [Effects of the Invention]

[0010] According to the present invention, a recovery method is provided that can recover cobalt and nickel from raw material powder containing cobalt, nickel, and copper with high efficiency while suppressing the inclusion of copper. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing an example of a drum-type wet magnetic separator. [Figure 2] Figure 2 is a schematic diagram showing another example of a drum-type wet magnetic separator. [Figure 3A] Figure 3A is a diagram showing an example of a horizontal matrix. [Figure 3B] Figure 3B is a diagram showing an example of a vertical matrix. [Figure 4] Figure 4 is a drawing showing an example of a matrix member in which three horizontal matrices and four vertical matrices are alternately stacked. [Figure 5] Figure 5 is a graph showing the composition of the cobalt-nickel leachate in Reference Example 1 and Reference Example 2. [Figure 6] Figure 6 is a graph showing the composition of the cobalt-nickel leachate in Comparative Example 1 and Examples 1 to 3.

Mode for Carrying Out the Invention

[0012] (Recovery Method) The recovery method is a recovery method for recovering cobalt and nickel from a raw material powder containing cobalt, nickel, and copper. The recovery method includes a slurrying step, an acid leaching step, and a neutralization step, and may further include other steps.

[0013] -Slurrying Step- The slurrying step is a step of mixing a raw material powder containing cobalt, nickel, and copper with water and phosphoric acid to obtain a slurry (raw material powder slurry).

[0014] The mixing method in the slurrying step is not particularly limited and can be appropriately selected according to the purpose. For example, a method of adding water and phosphoric acid to a raw material powder containing cobalt, nickel, and copper can be mentioned. In addition to the addition, stirring may be performed, or stirring may be performed while applying ultrasonic waves.

[0015] --Raw Material Powder-- The raw material powder is not particularly limited as long as it contains cobalt, nickel, and copper, and can be appropriately selected according to the purpose. Further, it can contain manganese, lithium, iron, aluminum, zinc, etc.

[0016] The raw material powder may be heat-treated material (battery powder) of a lithium-ion secondary battery. Alternatively, it may be material obtained by partially removing components such as molten aluminum from the heat-treated material, or it may be a product recovered by physically separating a lithium-ion secondary battery or its heat-treated material through crushing, classification, magnetic separation, etc. Specific examples of the components of the aforementioned raw material powder include, for example, those containing 1-20% cobalt, 5-50% nickel, and 0.1-10% copper.

[0017] There are no particular restrictions on the lithium-ion secondary battery, and it can be appropriately selected depending on the purpose. Examples include defective lithium-ion secondary batteries generated during the manufacturing process, lithium-ion secondary batteries discarded due to malfunctions of the equipment used, the end of the equipment's lifespan, and used lithium-ion secondary batteries discarded due to their lifespan.

[0018] There are no particular restrictions on the shape of the lithium-ion secondary battery, and it can be appropriately selected according to the purpose. Examples include laminated type, cylindrical type, button type, coin type, rectangular type, and flat type.

[0019] There are no particular restrictions on the form of the lithium-ion secondary battery, and it can be appropriately selected according to the purpose. Examples include battery cells, battery modules, and battery packs. The aforementioned battery module refers to a system in which multiple battery cells, which are individual batteries, are connected and assembled into a single enclosure. The aforementioned battery pack refers to a collection of multiple battery modules housed in a single enclosure. The battery pack may also include a control controller or a cooling device.

[0020] There are no particular restrictions on the structure, size, and material of the lithium-ion secondary battery, and they can be appropriately selected according to the purpose.

[0021] Examples of the lithium-ion secondary battery include one comprising a positive electrode, a negative electrode, a separator, an electrolyte solution containing an electrolyte and an organic solvent, and an outer container which is a battery case that houses the positive electrode, negative electrode, separator, and electrolyte solution. It should be noted that a lithium-ion secondary battery may also be one in which the positive electrode, negative electrode, etc., have fallen off.

[0022] The positive electrode is not particularly limited as long as it has a positive electrode active material containing at least one of cobalt and nickel, and can be appropriately selected depending on the purpose. There are no particular restrictions on the shape of the positive electrode, and it can be appropriately selected according to the purpose, for example, it can be a flat plate or a sheet.

[0023] There are no particular restrictions on the shape, structure, size, or material of the positive electrode current collector, and it can be appropriately selected according to the purpose. The shape of the positive electrode current collector can be, for example, a foil shape. Examples of materials for the positive electrode current collector include stainless steel, nickel, aluminum, copper, titanium, and tantalum. Among these, aluminum is preferred.

[0024] There are no particular restrictions on the cathode material, and it can be appropriately selected according to the purpose. For example, a cathode material that contains at least a lithium-containing cathode active material and optionally a conductive agent and a binder resin can be used.

[0025] The positive electrode active material is not particularly limited as long as it contains at least one of cobalt and nickel, and materials containing manganese, aluminum, iron, titanium, etc., can be appropriately selected depending on the purpose. Examples of the positive electrode active material include lithium manganese oxide (LiMn2O4), referred to as the LMO system; lithium cobalt oxide (LiCoO2), referred to as the LCO system; and LiNi, referred to as the ternary system and the NCM system. x Co y Mn z O2(x+y+z=1), LiNi, which is referred to as the NCA type.x Co y Al z (x+y+z=1), lithium iron phosphate (LiFePO4), lithium cobalt-nickelate (LiCo 1 / 2 Ni 1 / 2 Examples include O2 and lithium titanate (Li2TiO3). These may be used individually or in combination of two or more.

[0026] The conductive agent is not particularly limited and can be appropriately selected depending on the purpose. Examples include carbon black, graphite, carbon fiber, and metal carbides. The binder resin is not particularly limited and can be appropriately selected depending on the purpose. Examples include homopolymers or copolymers of vinylidene fluoride, tetrafluoroethylene, acrylonitrile, ethylene oxide, etc., and styrene-butadiene rubber.

[0027] The aforementioned negative electrode is not particularly limited as long as it has a negative electrode active material, and can be appropriately selected according to the purpose. There are no particular restrictions on the shape of the negative electrode, and it can be appropriately selected according to the purpose, for example, a flat plate shape, a sheet shape, etc.

[0028] There are no particular restrictions on the shape, structure, size, or material of the negative electrode current collector, and it can be appropriately selected according to the purpose. The shape of the negative electrode current collector can be, for example, a foil shape. Examples of materials for the negative electrode current collector include stainless steel, nickel, aluminum, copper, titanium, and tantalum. Among these, copper is preferred.

[0029] There are no particular restrictions on the negative electrode active material, and it can be appropriately selected depending on the purpose. Examples include carbon materials such as graphite and hard carbon, titanate, and silicon. These may be used individually or in combination of two or more.

[0030] The positive electrode current collector and the negative electrode current collector have a laminated structure, and there are no particular restrictions on the laminate; they can be appropriately selected according to the purpose.

[0031] There are no particular restrictions on the material of the outer casing (housing) of the lithium-ion secondary battery, and it can be appropriately selected according to the purpose. Examples include aluminum, iron, stainless steel, and resin (plastic).

[0032] The heat-treated lithium-ion secondary battery mentioned above refers to a product obtained by heat-treating the lithium-ion secondary battery. The heat-treated lithium-ion secondary battery may be a roasted product obtained by roasting a lithium-ion secondary battery.

[0033] There are no particular limitations on the method used for the heat treatment, and it can be appropriately selected depending on the purpose. For example, the heat treatment can be performed by heating the object in a known roasting furnace. There are no particular restrictions on the roasting furnace, and it can be appropriately selected according to the purpose. Examples include rotary kilns, fluidized bed furnaces, tunnel furnaces, batch-type furnaces such as muffle furnaces, cupolas, and stoker furnaces.

[0034] There are no particular restrictions on the atmosphere used for the heat treatment, and it can be appropriately selected according to the purpose. Examples include an air atmosphere, an inert atmosphere, a reducing atmosphere, and a low-oxygen atmosphere.

[0035] The aforementioned atmospheric atmosphere (air atmosphere) refers to an atmosphere using air containing approximately 21% oxygen by volume and approximately 78% nitrogen by volume. The aforementioned inert atmosphere can be exemplified by an atmosphere consisting of nitrogen or argon. The aforementioned reducing atmosphere refers to an atmosphere containing CO, H2, H2S, SO2, etc., in an inert atmosphere such as nitrogen or argon. The aforementioned low-oxygen atmosphere refers to an atmosphere in which the oxygen concentration is 11% by volume or less.

[0036] In the low-oxygen atmosphere, the oxygen concentration is preferably 0% by volume or more and 11% by volume or less, and more preferably 0% by volume or more and 5% by volume or less. By roasting the lithium-ion secondary battery in an atmosphere with an oxygen concentration of 11% by volume or less, the oxidation of valuable metals in the lithium-ion secondary battery can be suppressed. There are no particular restrictions on the method for adjusting the oxygen concentration, and it can be appropriately selected depending on the purpose. Examples include burning a gas burner or kerosene burner at a low air ratio, or using a mixture of an inert gas such as nitrogen or argon with air. Furthermore, roasting under an inert gas atmosphere such as nitrogen or argon (oxygen concentration 0 vol%) is more preferable because it suppresses the oxidation of valuable metals in lithium-ion secondary batteries.

[0037] There are no particular restrictions on the temperature (heat treatment temperature) in the heat treatment described above, and it can be appropriately selected according to the purpose, but it is preferably 400°C to 1,080°C, more preferably 660°C to 1,080°C, and particularly preferably 750°C to 900°C. The heat treatment temperature may be a temperature that is above the melting point of the current collector with the lower melting point among the positive electrode current collector and the negative electrode current collector, and below the melting point of the current collector with the higher melting point.

[0038] The heat treatment temperature refers to the temperature of the lithium-ion secondary battery, which is the object being heat-treated. The heat treatment temperature can be measured by inserting a thermometer, such as a coupler or thermistor, into the object during heat treatment. By setting the heat treatment temperature to 400°C or higher, the cobalt oxide and nickel oxide contained in the positive electrode active material are reduced to metal. Furthermore, these metals can be grown to a particle size that is easily magnetically attached in the subsequent magnetic separation process. This particle size growth is more likely to occur with higher heat treatment temperatures. Furthermore, by setting the heat treatment temperature to 660°C or higher, it becomes possible to melt the aluminum that constitutes the outer casing of the LIB pack and cell, and separate and recover it from other components. Also, by setting the heat treatment temperature to 750°C or higher, the lithium in Li(Ni / Co / Mn)O2 in the positive electrode active material and LiPF6 in the electrolyte can be converted into substances that are soluble in aqueous solutions, such as lithium fluoride (LiF), lithium carbonate (Li2CO3), and lithium oxide (Li2O), which can then be leached into the dispersion medium during the slurrying process.

[0039] It is preferable that the outer casing of the lithium-ion secondary battery is made of a material having a melting point higher than the heat treatment temperature. If the outer casing of the lithium-ion secondary battery is made of a material having a melting point lower than the heat treatment temperature, it is preferable to perform the heat treatment in a low-oxygen atmosphere with an oxygen concentration of 11 volume% or less, or at least in the interior of the lithium-ion secondary battery during roasting (especially the positive electrode current collector and negative electrode current collector located inside the outer casing of the lithium-ion secondary battery) with an oxygen concentration of 11 volume% or less.

[0040] As a method for achieving the low-oxygen atmosphere, for example, the positive or negative electrode of a lithium-ion secondary battery may be placed in an oxygen-shielding container and heat-treated. The material of the oxygen-shielding container is not particularly limited as long as it has a melting point above the heat treatment temperature, and can be appropriately selected according to the purpose. For example, if the heat treatment temperature is 800°C, materials such as iron and stainless steel, which have a melting point higher than this heat treatment temperature, can be used.

[0041] It is preferable to provide an opening in the oxygen shielding container to release the gas pressure of gases generated by combustion of the electrolyte, etc., in the lithium-ion secondary battery or laminate. It is preferable that the opening area of ​​the opening is 12.5% ​​or less of the surface area of ​​the outer container in which the opening is provided. More preferably, the opening area of ​​the opening is 6.3% or less of the surface area of ​​the outer container in which the opening is provided. The aforementioned opening has no particular restrictions on its shape, size, or location, and can be appropriately selected according to the purpose.

[0042] There are no particular restrictions on the time (heat treatment time) in the heat treatment described above, and it can be appropriately selected according to the purpose, but it is preferably between 1 minute and 10 hours, and more preferably between 1 minute and 3 hours. The heat treatment time should be sufficient to reach the desired temperature at which cobalt and nickel undergo metallization, and the holding time should be sufficient to allow time for metallization to progress. Having the heat treatment time within a preferred range is advantageous in terms of the cost of the heat treatment. Therefore, it is preferable to perform the heat treatment at a temperature of 400°C to 1,080°C for at least one hour.

[0043] --Water and phosphoric acid-- There are no particular restrictions on the water used in the slurrying process, and it can be appropriately selected depending on the purpose. Examples include pure water such as industrial water, tap water, ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water. Among these, ion-exchanged water is preferred because it has relatively low manufacturing costs and relatively low impurity concentrations.

[0044] There are no particular restrictions on the amount of water mixed in the slurrying process, and it can be appropriately selected depending on the purpose, but it is preferably 100g to 1000g per 100g of raw material powder, more preferably 200g to 800g, and even more preferably 300g to 500g.

[0045] There are no particular restrictions on the solid-liquid ratio (concentration (mass ratio) of raw material powder to water) in the slurrying process, and it can be appropriately selected according to the purpose, but it is preferably 1% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, and even more preferably 20% by mass or more and 30% by mass or less.

[0046] There are no particular restrictions on the lower limit of the amount of phosphoric acid mixed in the slurrying step, and it can be appropriately selected depending on the purpose. However, in terms of suppressing the inclusion of copper, it is preferable that the amount be 0.01 molar equivalent or more, more preferably 0.05 molar equivalent or more, even more preferably 0.1 molar equivalent or more, particularly preferably 0.4 molar equivalent or more, and most preferably 0.5 molar equivalent or more, relative to the total amount of impurity metals other than valuable metals, including cobalt and nickel, in the raw material powder. There is no particular upper limit to the amount of phosphoric acid mixed in the slurrying step, and it can be appropriately selected depending on the purpose. However, in order to suppress the inclusion of copper, it is preferable that the amount be 2 molar equivalents or less, more preferably 1.5 molar equivalents or less, even more preferably 1.2 molar equivalents or less, and particularly preferably 1.1 molar equivalents or less, relative to the total molar amount of impurity metals other than valuable metals, including cobalt and nickel, in the raw material powder. Furthermore, a range of values ​​where one of the values ​​indicated as the lower limit and one of the values ​​indicated as the upper limit are used as the preferred range. Among these, a range of 0.01 molar equivalents or more and 2 molar equivalents or less is preferred, a range of 0.01 molar equivalents or more and 1.5 molar equivalents or less is more preferred, a range of 0.05 molar equivalents or more and 1.2 molar equivalents or less is even more preferred, and a range of 0.4 molar equivalents or more and 1.2 molar equivalents or less is particularly preferred. In this invention, examples of impurity metals include iron, aluminum, copper, and zinc, while valuable metals including cobalt and nickel are cobalt, nickel, lithium, and manganese.

[0047] There are no particular restrictions on the concentration of phosphoric acid mixed in the slurrying step, and it can be appropriately selected depending on the purpose, but it is preferably 50% by mass or more and 95% by mass or less, preferably 70% by mass or more and 95% by mass or less, and more preferably 80% by mass or more and 90% by mass or less. In this specification, phosphoric acid refers to orthophosphoric acid (H3PO4). Furthermore, the phosphoric acid may be added together with the acid added in the following acid leaching step.

[0048] -Acid leaching process- The acid leaching step is a step of mixing the slurry (raw material powder slurry) obtained in the slurrying step with an acid and an oxidizing agent to obtain an acid leaching solution.

[0049] There are no particular restrictions on the mixing method in the acid leaching step, and it can be appropriately selected depending on the purpose. For example, one method is to add an acid and an oxidizing agent to the slurry obtained in the slurry formation step. In addition to the above additions, the mixture may be stirred, or stirred while applying ultrasonic waves.

[0050] --Acids and oxidizing agents-- The acid is not particularly limited and can be appropriately selected depending on the purpose, but sulfuric acid is preferred.

[0051] There are no particular restrictions on the concentration of sulfuric acid mixed in the acid leaching process, and it can be appropriately selected depending on the purpose, but it is preferably 5% by mass or more and 99% by mass or less, preferably 50% by mass or more and 99% by mass or less, and more preferably 90% by mass or more and 99% by mass or less.

[0052] There are no particular restrictions on the oxidizing agent, and it can be appropriately selected depending on the purpose, but sodium hypochlorite or hydrogen peroxide are preferred in terms of recovering cobalt and nickel with high efficiency.

[0053] There are no particular restrictions on the concentration of sodium hypochlorite mixed in the acid leaching process, and it can be appropriately selected depending on the purpose. However, in terms of recovering cobalt and nickel with high efficiency, a concentration of 5% to 30% by mass is preferred, 10% to 20% by mass is preferred, and 11% to 15% by mass is even more preferred.

[0054] There are no particular restrictions on the pH at the end of the acid leaching process, and it can be appropriately selected depending on the purpose. However, in terms of recovering cobalt and nickel with high efficiency, a pH of 0 to 3.5 is preferred, 0 to 3.0 is more preferred, 1.0 to 3.0 is even more preferred, and 1.5 to 2.5 is particularly preferred.

[0055] There are no particular restrictions on the oxidation-reduction potential (ORP) at the end of the acid leaching process, and it can be appropriately selected depending on the purpose. However, in terms of recovering cobalt and nickel with high efficiency, -250mV to 0mV is preferred, -250mV to -50mV is more preferred, -250mV to -150mV is even more preferred, and -250mV to -200mV is particularly preferred. The aforementioned oxidation-reduction potential is the oxidation-reduction potential measured with respect to the silver-silver chloride electrode. The aforementioned oxidation-reduction potential can be measured, for example, using an oxidation-reduction potential measuring instrument with a silver-silver chloride electrode as the reference electrode.

[0056] -Neutralization process- The neutralization step involves adding alkali to the acid leaching solution obtained in the acid leaching step. The aforementioned neutralization process can remove impurity metals.

[0057] Solid-liquid separation may be performed after adding the aforementioned alkali. There are no particular limitations on the solid-liquid separation method, and it can be appropriately selected depending on the purpose. Examples include filtration.

[0058] There are no particular restrictions on the alkali (neutralizing agent) and it can be appropriately selected depending on the purpose. For example, caustic soda (sodium hydroxide) can be used. In addition to the alkali (neutralizing agent), the oxidizing agent may also be added.

[0059] When the added caustic soda is in solution form, there are no particular restrictions on its concentration, and it can be appropriately selected depending on the purpose. However, a concentration of 30% to 70% by mass is preferred, 40% to 60% by mass is preferred, and 45% to 50% by mass is even more preferred.

[0060] There are no particular restrictions on the pH at the end of the neutralization process, and it can be appropriately selected depending on the purpose. However, in terms of suppressing copper contamination, a pH of 0 to 7.0 is preferred, 1.0 to 6.0 is more preferred, 3.0 to 5.0 is even more preferred, and 4.5 to 5.0 is particularly preferred.

[0061] There are no particular restrictions on the oxidation-reduction potential (ORP) at the end of the neutralization process, and it can be appropriately selected depending on the purpose. However, in terms of suppressing copper contamination, an ORP of 200mV to 600mV is preferred, 300mV to 550mV is more preferred, 300mV to 400mV is even more preferred, and 300mV to 350mV is particularly preferred. The aforementioned oxidation-reduction potential is the oxidation-reduction potential measured with respect to the silver-silver chloride electrode. The aforementioned oxidation-reduction potential can be measured, for example, using an oxidation-reduction potential measuring instrument with a silver-silver chloride electrode as the reference electrode.

[0062] -Other processes- The aforementioned other processes are not particularly limited and can be appropriately selected depending on the purpose. Examples include a heat treatment process, a crushing process, a first classification process, a dispersion process, a grinding process, a second classification process, a first magnetic separation process, and a second magnetic separation process. The recovery method of the present invention can be implemented without including a solvent extraction step. In the present invention, cobalt and nickel can be recovered with high efficiency from raw material powder containing cobalt, nickel, and copper, while suppressing the inclusion of copper, without using solvent extraction, which has high equipment costs due to explosion-proof equipment and solvent costs during operation.

[0063] The raw material powder may be the heat-treated product of the lithium-ion secondary battery, the heat-treated product from which some components such as molten aluminum have been partially removed, the product recovered by performing physical separation such as crushing or classification on the heat-treated product or the heat-treated product from which some components have been partially removed, or the magnetically deposited product obtained by magnetic separation of these products. The raw material powder can be obtained by processing the lithium-ion secondary battery in any or a combination of the following steps: heat treatment, crushing, first classification, dispersion, pulverization, second classification, first magnetic separation, and second magnetic separation.

[0064] --Heat Treatment Process-- The heat treatment step is a step of heat-treating the lithium-ion secondary battery. In the heat treatment step, a heat-treated product of the lithium-ion secondary battery can be obtained. The aforementioned heat treatment is as described in the "--raw material powder--" section of the "--slurry formation process--" above.

[0065] --Crushing Process-- The crushing step is a step of obtaining crushed material by crushing the heat-treated material obtained in the heat treatment step. The aforementioned crushed material refers to material obtained by crushing heat-treated material.

[0066] The crushing process is not particularly limited as long as it is a process that crushes the heat-treated material to obtain crushed material, and can be appropriately selected according to the purpose, but it is preferable to crush the heat-treated material by impact to obtain crushed material. Furthermore, if the outer casing of the lithium-ion secondary battery does not melt during heat treatment, it is even more preferable to pre-crush the heat-treated material by cutting it with a cutting machine before applying impact to the heat-treated material.

[0067] Methods of crushing by impact include, for example, throwing the heat-treated material with a rotating impact plate and striking it against an impact plate to apply impact, or striking the heat-treated material with a rotating beater, and can be carried out by a hammer crusher, for example. Another method of crushing by impact is striking the heat-treated material with a ball made of ceramic or similar material, and this method can be carried out by a ball mill, for example. Furthermore, crushing by impact can also be carried out using, for example, a twin-shaft shredder with a short blade width and blade length that is used for crushing by compression. Furthermore, methods of crushing by impact include, for example, using two rotating chains to strike the heat-treated material and apply impact, which can be done, for example, with a chain mill.

[0068] By crushing the heat-treated material through impact, the crushing of the positive electrode current collector (e.g., aluminum (Al)) is promoted, but the negative electrode current collector (e.g., copper (Cu)), whose shape has not changed significantly, remains in a foil-like form. Therefore, in the crushing process, the negative electrode current collector is only cut, so in the first classification process (classification process) described later, it is possible to obtain crushed material in a state where valuable materials derived from the positive electrode current collector and valuable materials derived from the negative electrode current collector can be efficiently separated.

[0069] There are no particular restrictions on the crushing time in the crushing process, and it can be appropriately selected according to the purpose. However, the crushing time per 1 kg of lithium-ion secondary battery is preferably 1 second to 30 minutes, more preferably 2 seconds to 10 minutes, and particularly preferably 3 seconds to 5 minutes.

[0070] --First Classification Process-- The first classification step is a step of obtaining a coarse-grained product 1 and a fine-grained product by classifying the crushed material obtained in the crushing step.

[0071] The first classification step includes a process to obtain a coarse-grained product 1 and a fine-grained product by classifying the crushed material at a classification point of 600 μm or more and 2,400 μm or less, and it is preferable to classify at a classification point of 850 μm or more and 1,700 μm or less. The first classification step described above is not particularly limited as long as it classifies the crushed material to obtain coarse-grained product 1 (sieved product) and fine-grained product (undersieved product), and can be appropriately selected according to the purpose.

[0072] There are no particular restrictions on the classification method in the first classification step described above, and it can be appropriately selected according to the purpose. For example, it can be carried out using a vibrating screen, a multi-stage vibrating screen, a cyclone, a standard screen of JIS Z8801, a wet vibrating table, an air table, etc. Through classification, copper (Cu), iron (Fe), etc. can be separated into the coarse-grained product 1, and lithium, cobalt, nickel, or carbon can be concentrated into the fine-grained product.

[0073] In the first classification step described above, the particle size (classification point, sieve opening) is set to a classification point of 600 μm to 2,400 μm, in order to separate copper (Cu), iron (Fe), aluminum (Al), etc. into the coarse-grained product 1 and concentrate carbon (C), lithium (Li), cobalt (Co), nickel (Ni), manganese (Mn), etc. into the fine-grained product.

[0074] When using a sieve as the classification method, by placing, for example, stainless steel balls or alumina balls on the sieve as a crushing accelerator and performing the classification, smaller crushed material adhering to larger crushed material can be separated from the larger crushed material. This allows for more efficient separation of large and small crushed material, further improving the quality of the recovered metal.

[0075] In the first classification step described above, the crushing process can also be carried out simultaneously with the classification process. For example, the heat-treated material obtained in the heat treatment step may be crushed, and the crushed material may be classified into coarse-grained product 1 and fine-grained product in a crushing and classification step (crushing and classification). If the proportion of fine-grained products is low in the first classification process (classification treatment), the coarse-grained product 1 can be returned to the process of crushing the heat-treated material.

[0076] --Dispersion process-- The dispersion step involves immersing the fine-grained product obtained after the first classification step in water (dispersion treatment) to obtain an aqueous dispersion of the fine-grained product, which is a slurry-like liquid (fine-grained product slurry). In the grinding process described later, if wet grinding is performed, it is preferable to perform the dispersion process described above.

[0077] The aforementioned dispersion process is not particularly limited as long as it involves immersing (soaking, placing in water) the fine-grained product recovered in the first classification process in water to disperse the fine-grained product in water and obtain a slurry (suspension). It can be appropriately selected according to the purpose.

[0078] There are no particular restrictions on the dispersion medium used to disperse the fine-grained product, and it can be appropriately selected depending on the purpose. Examples include pure water such as industrial water, tap water, ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water.

[0079] There are no particular restrictions on the dispersion method, and it can be appropriately selected depending on the purpose. Examples include simply placing the granular product in water, placing the granular product in water and stirring, placing the granular product in water and stirring while applying ultrasonic waves, and adding water to the granular product. Among these, the method of placing the granular product in water and stirring is preferred, and the method of placing the granular product in water and stirring while applying ultrasonic waves is more preferred.

[0080] There are no particular restrictions on the solid-liquid ratio (concentration (mass ratio) of the fine-grained product to water) in the dispersion treatment described above, and it can be appropriately selected according to the purpose, but it is preferably 1% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 20% by mass or less. If the solid-liquid ratio is less than 1% by mass, cobalt and nickel, which would normally be recovered as magnetic deposits, will not be recovered by the magnetic separator and will be lost to non-magnetic deposits, which is likely to reduce the recovery rate of cobalt and nickel. If the solid-liquid ratio exceeds 50% by mass, the amount of impurities trapped in the magnetic material increases, which may lead to a decrease in cobalt and nickel content.

[0081] There are no particular restrictions on the stirring speed of the water in the aforementioned dispersion treatment, and it can be appropriately selected according to the purpose; for example, it can be set to 200 rpm. There are no particular restrictions on the leaching time in the aforementioned distributed processing; it can be appropriately selected depending on the purpose, for example, it can be 1 hour.

[0082] --Grinding Process-- The aforementioned grinding process is a step of grinding the fine granular product to obtain a pulverized material of a predetermined size.

[0083] There are no particular restrictions on the grinding method, and it can be appropriately selected depending on the purpose. For example, it can be carried out using a media-agitating grinder that uses a medium such as iron balls (attritor, bead mill, tower mill), a roller mill, a jet mill, a high-speed rotary grinder (hammer mill, pin mill), or a container-driven mill (rotary mill, vibratory mill, planetary mill).

[0084] The aforementioned grinding process can be either wet or dry, and can be appropriately selected depending on the purpose, but the wet process is preferred. By performing the grinding process in a wet manner, the decrease in the recovery rate of cobalt (Co) and nickel (Ni) due to dust generation at each step can be suppressed, and measures to prevent dust dispersion into the surrounding atmosphere become unnecessary.

[0085] The particle size (90% particle size) of the pulverized material is preferably 1,000 μm or less, more preferably 750 μm or less, and particularly preferably 500 μm or less. The 90% particle size is, for example, the particle size that accounts for 90% of the integrated particle size distribution obtained by measuring with a laser diffraction scattering particle size distribution analyzer.

[0086] The number average particle size of at least one or both of the cobalt and nickel contained in the pulverized material is preferably 100 μm or less, more preferably 75 μm or less, and particularly preferably 50 μm or less. The aforementioned number-average particle size is, for example, the average value calculated by measuring the particle sizes of a total of 100 cobalt and nickel particles using electron microscopy.

[0087] A smaller 90% particle size or number-average particle size promotes the separation of cobalt and nickel from other components, thereby improving the cobalt and nickel quality of magnetic deposits 1 and 2 recovered in the first and second magnetic separation processes described below. Even if the 90% particle size or number-average particle size is small, the recovery rate of cobalt and nickel in the first and second magnetic separation processes can be increased, so further recovery processes such as a third magnetic separation process may be provided as needed.

[0088] --Second Classification Process-- The second classification step is a step in which the pulverized material obtained in the pulverization step is classified at a classification point smaller than the classification point of the first classification step, thereby obtaining a coarse-grained product 2 and a fine-grained product.

[0089] In the second classification step, the pulverized material is classified at a classification point smaller than that of the first classification step, and between 75 μm and 1,200 μm, thereby obtaining a coarse-grained product 2 and a fine-grained product. For example, when the second classification step is performed using a JIS Z8801 standard sieve with a classification point of 500 μm, the product on the sieve surface of the standard sieve with a classification point of 500 μm is the coarse-grained product 2, and the product below the sieve surface is the fine-grained product. Copper can be concentrated and recovered from the coarse-grained product 2.

[0090] The classification point used in the second classification step is preferably 25 μm to 1,700 μm, more preferably 75 μm to 1,200 μm, even more preferably 75 μm to 850 μm, and particularly preferably 106 μm to 600 μm. If the classification point exceeds 1,700 μm, the inclusion of copper in the fine-grained product increases, and the cobalt and nickel grades may decrease. If the classification point falls below 25 μm, the grinding energy required to recover cobalt and nickel in the fine-grained product may become excessive.

[0091] There are no particular restrictions on the classification method in the second classification step described above, and it can be appropriately selected according to the purpose. For example, it can be carried out using a vibrating screen, a multi-stage vibrating screen, a cyclone, a standard screen of JIS Z8801, a wet vibrating table, an air table, etc. The second classification step described above is not particularly limited and can be appropriately selected depending on the purpose, but it is preferable to perform it wet. When wet classification is performed, the aqueous dispersion of the pulverized material obtained from the wet pulverization process may be supplied as is, or a dispersion medium (water) may be added to the aqueous dispersion of the pulverized material to dilute it and adjust the solid-liquid ratio.

[0092] When the second classification process is carried out in a wet manner and a vibrating screen or a multi-stage vibrating screen is used, showering the top of the screen with a dispersion medium (water) suppresses the aggregation of the pulverized material during classification, thereby obtaining good classification results.

[0093] The phase angle of the weight of the vibrating screen is preferably 30° to 90°, more preferably 40° to 80°, and particularly preferably 50° to 70°. By setting the phase angle to this value, excessive discharge of crushed material and classified products outside the screening device (insufficient residence time on the screen) can be prevented, and good classification results can be obtained.

[0094] --First Magnetic Separation Process-- The first magnetic separation step is a step in which the fine-grained product obtained in the second classification step is magnetically separated to obtain magnetically attached material 1 and non-magnetically attached material 1.

[0095] The magnetic object 1 refers to an object that, due to the magnetic force generated by a magnetic source (for example, a magnet or electromagnet), generates an attractive force between itself and the magnetic source and can be attracted to the magnetic source. Examples of the magnetic material 1 include ferromagnetic metals. Examples of ferromagnetic metals include iron (Fe), nickel (Ni), and cobalt (Co).

[0096] The non-magnetic material 1 refers to a material that is not attracted to the magnetic source by the magnetic force generated by the magnetic source. There are no particular restrictions on the non-magnetic material, and it can be selected according to the purpose. Examples of non-magnetic metals include paramagnetic or semimagnetic metals. Examples of paramagnetic or semimagnetic metals include aluminum (Al), manganese (Mn), gold (Au), silver (Ag), and copper (Cu).

[0097] The first magnetic separation step may be either dry magnetic separation or wet magnetic separation, but wet magnetic separation is preferred for the following reasons. When magnetically separating the fine particles obtained in the second classification step, for example, if dry magnetic separation is performed, particle aggregation may occur due to moisture adhering between particles, and it may not be possible to sufficiently separate the metal particles derived from the negative electrode current collector and the fine particles of the negative electrode active material, cobalt particles, and nickel particles that are present in 10% or more of the fine particles. For this reason, it is preferable to perform wet magnetic separation to separate the material derived from the negative electrode active material and the metal derived from the negative electrode current collector into a non-magnetic slurry, and to recover the cobalt and nickel as magnetic material 1.

[0098] In the wet magnetic separation process, the aqueous dispersion of the fine particles obtained in the second wet classification step may be supplied as is, or the aqueous dispersion of the fine particles may be concentrated or diluted by solid-liquid separation such as sedimentation separation to adjust the solid-liquid ratio. Alternatively, the solid-liquid ratio may be adjusted by adding water to the slurry of the fine particles to dilute it.

[0099] There are no particular restrictions on the solid-liquid ratio (concentration (mass ratio) of the fine product relative to water) of the slurry supplied to the wet magnetic separator, and it can be appropriately selected according to the purpose, but it is preferably 5% by mass or more and 67% by mass or less, and more preferably 10% by mass or more and 40% by mass or less. If the solid-liquid ratio is less than 5% by mass, the recovery rate of cobalt and nickel as magnetic deposits in the wet magnetic separator may decrease. When the solid-liquid ratio exceeds 67% by mass, problems such as pump blockage during slurry supply are likely to occur, and the separation performance of cobalt and nickel (magnetic materials) from non-magnetic materials such as carbon may decrease.

[0100] There are no particular restrictions on the method of supplying the aqueous dispersion, and it can be appropriately selected according to the purpose, but it may also be supplied by pumping while stirring the aqueous dispersion in the tank.

[0101] There are no particular restrictions on the magnetic separation method in the first magnetic separation step, and it can be carried out using a known magnetic separator (magnetic separator), for example, a drum-type magnetic separator or a high-gradient magnetic separator. Among these, the method using a drum-type magnetic separator is preferred.

[0102] The magnetic flux density for magnetic separation in the first magnetic separation step is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.05T or more and 0.9T or less, more preferably 0.075T or more and 0.6T or less, still preferably 0.1T or more and less than 0.3T, and particularly preferably 0.1T or more and 0.2T or less. If the magnetic flux density is less than 0.05T, it becomes difficult to magnetically attach cobalt and nickel fine particles, and the recovery rate of cobalt and nickel in the magnetically attached material tends to decrease. When the magnetic flux density exceeds 0.9T, the recovery rate of impurities other than cobalt and nickel into the magnetic deposit 1 increases, which may lead to a decrease in the cobalt and nickel content in the magnetic deposit 1.

[0103] Examples of drum-type wet magnetic separation methods in the first magnetic separation process include: (1) as shown in Figure 1, a magnet is placed at the 6 o'clock position on the drum, a non-magnetic slurry is introduced from the 3 o'clock position (side), and the drum is rotated clockwise; and (2) as shown in Figure 2, a magnet is placed near the 3 o'clock position on the drum, a non-magnetic slurry is introduced from the 12 o'clock to 2 o'clock position (top) of the drum, and the drum is rotated counterclockwise. Among these methods, (1) the drum-type wet magnetic separation method shown in Figure 1 is preferred because it yields high-quality magnetic deposits of cobalt and nickel.

[0104] --Second Magnetic Separation Process-- The second magnetic separation step is a step in which the non-magnetic material 1 obtained in the first magnetic separation step is magnetically separated to obtain magnetic material 2 and non-magnetic material 2. If the second magnetic separation step recovers dust generated during the transfer of the fine-grained product obtained in the first classification step, the collected dust can also be included as the target of magnetic separation.

[0105] The combined quality of cobalt and nickel contained in the non-magnetic material 1 obtained in the first magnetic separation step is preferably 30% or less, more preferably 20% or less, and particularly preferably 15% or less. Even if the non-magnetic material 1 has a combined cobalt and nickel content of 30% or less, it can be recovered as magnetic material in the second magnetic separation process, thereby improving the recovery rate of cobalt and nickel. However, it is a well known fact that the higher the cobalt and nickel content of the non-magnetic material, the easier it is to recover cobalt and nickel into the magnetic material.

[0106] The number average particle size of at least one of the cobalt and nickel contained in the non-magnetic material 1 obtained in the first magnetic separation step is preferably 50 μm or less, more preferably 35 μm or less, and particularly preferably 25 μm or less. The aforementioned number-average particle size is, for example, the average value calculated by measuring the particle sizes of a total of 100 cobalt and nickel particles using electron microscopy. A smaller number-average particle size promotes the separation of cobalt and nickel from other components, thereby improving the cobalt and nickel quality of the magnetically deposited material 2 recovered in the second magnetic separation step. Furthermore, since the recovery rate of cobalt and nickel in the second magnetic separation step can be increased, a third magnetic separation step or other further recovery steps may be provided as needed. Even cobalt and nickel particles with an average particle size of 50 μm or less can be recovered as magnetically deposited material in the second magnetic separation step, thereby improving the recovery rate of cobalt and nickel throughout the entire process.

[0107] There are no particular restrictions on the magnetic separation method in the second magnetic separation step, and it can be carried out using a known magnetic separator (magnetic separator), for example, a drum-type magnetic separator or a high-gradient magnetic separator.

[0108] The magnetic flux density for magnetic separation in the second magnetic separation step is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.3T or more and 2T or less, more preferably 0.4T or more and 1.8T or less, and particularly preferably 0.6T or more and 1.2T or less. If the magnetic flux density is less than 0.3T, it becomes difficult to magnetically attach cobalt and nickel fine particles, and the recovery rate of cobalt and nickel in the magnetically attached material tends to decrease. When the magnetic flux density exceeds 2T, the recovery rate of impurities other than cobalt and nickel into the magnetic deposit 2 increases, which may lead to a decrease in the cobalt and nickel content in the magnetic deposit 2.

[0109] The second magnetic separation step is preferably carried out by wet magnetic separation. As for the wet magnetic separation method, a method using a high-gradient wet magnetic separation method or a drum-type wet magnetic separation method is preferred.

[0110] The aforementioned high-gradient wet magnetic separation method can be repeated two or more times. In the aforementioned high-gradient wet magnetic separation method, it is preferable to use a matrix in order to increase the change in magnetic flux density. As the aforementioned matrix, for example, a horizontal iron matrix (line width: 2 mm, thickness: 4 mm, width 200 mm x height 50 mm) shown in Figure 3A and a vertical iron matrix (maximum rhombus length: 22 mm, minimum rhombus length: 10 mm, thickness: 4 mm, width 200 mm x height 50 mm) shown in Figure 3B can be used. A matrix member (width 200 mm x height 50 mm x thickness: 28 mm) shown in Figure 4 can be used, which is formed by alternately stacking and bundling three horizontal matrices from Figure 3A and four vertical matrices from Figure 3B.

[0111] Examples of the aforementioned drum-type wet magnetic separation method include a method in which a non-magnetic material slurry is introduced into a rotating drum having a magnet. There are no particular restrictions on the direction of rotation; it can be selected as appropriate depending on the purpose, and it may be clockwise or counterclockwise. There are no particular restrictions on the position of the magnet in the drum, and it can be appropriately selected according to the purpose. For example, it may be in the same position as the non-magnetic slurry input position, or it may be in a different position from the non-magnetic slurry input position.

[0112] Specific examples of the drum-type wet magnetic separation method include, for example, (1) as shown in Figure 1, a magnet is placed at the 6 o'clock position on the drum, a non-magnetic slurry is introduced from the 3 o'clock position (side), and the drum is rotated clockwise; and (2) as shown in Figure 2, a magnet is placed near the 3 o'clock position on the drum, a non-magnetic slurry is introduced from the vicinity of the 12 o'clock to 2 o'clock position (top) on the drum, and the drum is rotated counterclockwise. Among these methods, the drum-type wet magnetic separation method shown in Figure 2 (2) is preferred because it allows for high recovery rates of cobalt and nickel. In the method described in Figure 2 (2), the magnetic material attracted to the magnet is carried in the 9 o'clock direction by the rotation of the drum and recovered, while the non-magnetic material slurry 2 flows along the drum surface in the 3 o'clock to 6 o'clock direction and is discharged from the 6 o'clock direction.

[0113] The second magnetic separation step can be carried out by adding a dispersant to the non-magnetic slurry obtained in the first magnetic separation step. By adding a dispersant to the non-magnetic slurry, the magnetic separation efficiency of the second magnetic separation step can be improved. There are no particular restrictions on the dispersant, and it can be appropriately selected depending on the purpose. For example, dispersants used in the fields of dyes, pigments, pesticides, and inorganic materials can be used. Examples of the dispersant include a condensate of aromatic sulfonic acid and formalin, and an anionic surfactant mainly composed of a special carboxylic acid type polymer surfactant (for example, the surfactants in the "Demol" series manufactured by Kao Corporation).

[0114] Additional magnetic separation may be performed on the magnetic material 1 and magnetic material 2 or either thereof, and additional magnetic separation may be performed on the non-magnetic material 1 and non-magnetic material 2 or either thereof.

[0115] The combined cobalt and nickel content in the magnetically deposited material obtained by the wet magnetic separation method is preferably concentrated to 1.3 times or more, and more preferably to 1.5 times or more, than the combined cobalt and nickel content in the fine-grained product.

[0116] Solid-liquid separation may be performed on the magnetically deposited material obtained by the wet magnetic separation method described above. There are no particular restrictions on the solid-liquid separation method, and it can be appropriately selected according to the purpose. For example, a solid-liquid separation method using a filter press can be used. [Examples]

[0117] The following describes embodiments of the present invention, but the present invention is not limited in any way to these embodiments.

[0118] <Manufacturing of raw material powders> (Manufacturing example) -Heat treatment process- The waste lithium-ion secondary batteries (approximately 300 kg) to be processed were subjected to heat treatment using a batch-type burner furnace from Ecosystem Akita Co., Ltd. as the heat treatment device. The heat treatment was performed at a temperature of 750°C (heating up from 20°C to 750°C over 15 minutes, then holding for 3 hours) under air conditions to obtain a heat-treated product.

[0119] -Crushing Process- Next, a chain mill (cross-flow shredder S-1000, manufactured by Sato Iron Works Co., Ltd.) was used as a crushing device to crush the heat-treated lithium-ion secondary batteries under conditions of 50Hz (chain tip speed: approximately 60m / sec) and residence time of 50 seconds, thereby obtaining the crushed lithium-ion secondary battery material.

[0120] -First Classification Process- Next, the crushed lithium-ion secondary battery material was sieved using a vibrating sieve with a mesh size of 1.2 mm (200 mm in diameter, manufactured by Tokyo Screen Co., Ltd.). After sieving, the 1.2 mm sieved product (coarse-grained product 1) and the unsieved product (fine-grained product) were collected separately. The cobalt grade of the fine-grained product (black mass) was 6.2%, the nickel grade was 13.5%, and the combined grade was 19.7%.

[0121] -Dispersion process- The obtained 62.5 kg of granular product was immersed in 250 L of water and dispersed under conditions of a solid-liquid ratio of 25%, a stirring speed of 400 rpm, and a leaching time of 1 hour to obtain an aqueous dispersion of the granular product.

[0122] -Wet grinding process- The obtained fine-grained product aqueous dispersion and 10 kg of grinding medium (iron balls) were used with a medium-agitating type grinder (tower mill NE008, manufactured by Nippon Eirich Co., Ltd.). The aqueous dispersion of the fine-grained product was supplied in 20 portions, and wet grinding was performed for 30 minutes at a rotation speed of 716 rpm (peripheral speed of 3 m / sec) per portion.

[0123] -Second Classification Process- Next, the aqueous dispersion of the fine-grained product obtained by wet grinding was subjected to wet classification using JIS Z8801 standard sieves with mesh sizes of 500 μm and 250 μm. The product on the 500 μm sieve (coarse-grained product 2) and the product below the 250 μm sieve (aqueous dispersion of fine-grained product) were collected separately. The intermediate product generated on the 250 μm sieve was returned to the previous wet grinding process and ground repeatedly until it all passed through the 250 μm sieve.

[0124] -First Magnetic Separation Process- The obtained aqueous dispersion of fine particulate products (dispersion concentration 15% by mass) was subjected to a first magnetic separation process using a drum-type wet magnetic separator (manufactured by Elise Magnetics Co., Ltd., model: WD L-8 lab model) shown in Figure 1, with a magnetic flux density of 0.15 T and a drum rotation speed of 40 rpm, to recover the magnetically attached material 1 and the non-magnetic aqueous dispersion 1.

[0125] The drum-type wet magnetic separator shown in Figure 1 is a device in which a magnet is positioned at the 6 o'clock position on the drum, a water dispersion of fine particulate matter is introduced from the 3 o'clock position (side) of the drum, and magnetic separation is performed while the drum rotates clockwise.

[0126] For the obtained non-magnetic aqueous dispersion 1, the particle sizes of a total of 100 cobalt and nickel particles were measured by electron microscopy, and the number-average particle size was found to be 10 μm. Furthermore, the cobalt content of non-magnetic material 1 contained in the non-magnetic aqueous dispersion 1 was 3.4%, and the nickel content was 8.2%, for a combined content of 11.6%.

[0127] Solid-liquid separation was performed on the magnetic material 1 using a filter press (PF-3C25c-20, manufactured by Nippon Filtration Equipment Co., Ltd.), and the resulting recovered material was used as raw material powder.

[0128] In the solid-liquid separation using the filter press described above, the filter plate was closed and tightened to 11 MPa using a manual hydraulic pump, and the slurry liquid of the magnetic material 1 was pumped at a pressure of 0.4 MPa for filtration. After that, it was compressed at 0.4 MPa for about 30 minutes, and air blowing was performed at 0.6 MPa for about 15 minutes. After that, the tightening was released and the plate was opened.

[0129] <Recovery of cobalt and nickel> A 1L beaker was used as the container, and various operations were performed while stirring with a stirring blade at a liquid temperature of 40°C and a rotation speed of 400 rpm.

[0130] (Reference example 1: With oxidizing agent added) -Slurry Formation Process- 100 g of the raw material powder (black mass magnetized material) obtained in the above manufacturing example was mixed with 400 g of pure water to prepare a raw material slurry with a solid-liquid ratio of 25%.

[0131] -Acid leaching process- To the aforementioned raw material slurry, 125 g of 98% concentrated sulfuric acid (sulfuric acid, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 430 g of sodium hypochlorite (sodium hypochlorite, 12% available chlorine, manufactured by Kanto Denka Kogyo Co., Ltd.) were added at a constant rate over 4 hours. At the end of the addition, the pH of the solution was set to 1.9 or higher and 2.0 or lower, and the oxidation-reduction potential (ORP), measured using a silver-silver chloride electrode as a reference, was set to -250 mV or higher and 0 mV or lower. pH and oxidation-reduction potential (ORP) were measured using a pH / ORP meter (manufactured by Horiba, Ltd., F-73). The slurry after the addition of sodium hypochlorite as an oxidizing agent was subjected to solid-liquid separation to obtain the cobalt-nickel leaching solution at the end of the acid leaching process.

[0132] The cobalt-nickel leaching solution was sampled and recovered at the end of the acid leaching process. The composition (concentrations of various metals) of the recovered cobalt-nickel leachate was measured using an ICP emission spectrometer (ICP-OES) and is shown in Table 1 and Figure 5.

[0133] [Table 1]

[0134] (Reference example 2: No oxidizing agent added) In the acid leaching process in Reference Example 1, sodium hypochlorite was not added, and the oxidation-reduction potential measured using the silver-silver chloride electrode as a reference was not adjusted to between -250mV and -200mV. In the same manner as in Reference Example 1, the cobalt-nickel leaching solution was recovered and its composition was measured, as shown in Table 1 and Figure 5.

[0135] The results in Table 1 and Figure 5 show that acid leaching using an acid and an oxidizing agent can accelerate the leaching of cobalt and nickel. It was also found that the leaching of impurity metals such as copper and zinc is accelerated.

[0136] (Example 1: 0.5 molar equivalent of phosphoric acid) -Slurry Formation Process- 100 g of the raw material powder (black mass magnetized material) obtained in the above manufacturing example was mixed with 400 g of pure water to prepare a raw material slurry with a solid-liquid ratio of 25%. Furthermore, 14 g of 85% phosphoric acid was added so that it amounted to 0.5 molar equivalents relative to the molar amount of impurity metals (iron, aluminum, copper, zinc) contained in the raw material powder (black mass magnetized material).

[0137] -Acid leaching process- To the aforementioned raw material slurry, 90 g of 98% concentrated sulfuric acid as an acid and 324 g of sodium hypochlorite as an oxidizing agent were added at a constant rate over 4 hours to adjust the pH of the solution to 2.0, and the oxidation-reduction potential (ORP), measured using a silver-silver chloride electrode as a reference, was set to between -250 mV and 0 mV. pH and oxidation-reduction potential (ORP) were measured using a pH / ORP meter (F-73, manufactured by Horiba, Ltd.).

[0138] -Neutralization (impurity removal) process- To the above acid leaching slurry, 108 g of sodium hypochlorite as an oxidizing agent and 5 g of a 48% caustic soda aqueous solution (48% caustic soda, manufactured by Takasugi Pharmaceutical Co., Ltd.) were added at a constant rate over 2 hours to obtain an impurity-removed slurry. The pH of the solution was adjusted to between 4.5 and 5.0, and the oxidation-reduction potential (ORP), measured using a silver-silver chloride electrode as a reference, was adjusted to between 300 mV and 350 mV. pH and oxidation-reduction potential (ORP) were measured using a pH / ORP meter (F-73, manufactured by Horiba, Ltd.).

[0139] -Separation process- The slurry after the neutralization process described above was filtered, and 765 g of cobalt-nickel leaching solution was recovered. The composition (concentrations of various metals) of the recovered cobalt-nickel leachate was measured using an ICP emission spectrometer (ICP-OES), and is shown in Table 2 and Figure 6.

[0140] [Table 2]

[0141] (Example 2: 1.1 molar equivalents of phosphoric acid) In the slurrying process in Example 1, 85% phosphoric acid was added in an amount equal to 1.1 molar equivalents relative to the molar amount of impurity metals (iron, aluminum, copper, zinc) contained in the raw material powder (black mass magnetized material). The cobalt-nickel leaching solution was recovered in the same manner as in Example 1, and its composition was measured, as shown in Table 2 and Figure 6.

[0142] (Example 3: 0.1 molar equivalent of phosphoric acid) In the slurrying process in Example 1, 85% phosphoric acid was added in an amount equal to 0.1 molar equivalents relative to the molar amount of impurity metals (iron, aluminum, copper, zinc) contained in the raw material powder (black mass magnetized material). The cobalt-nickel leaching solution was recovered in the same manner as in Example 1, and its composition was measured, as shown in Table 2 and Figure 6.

[0143] (Comparative Example 1: No phosphoric acid added) In the slurrying process of Example 1, the cobalt-nickel leaching solution was recovered and its composition measured, as shown in Table 2 and Figure 6, except that phosphoric acid was not added.

[0144] The results in Table 2 and Figure 6 show that by mixing the raw material powders containing cobalt, nickel, and copper with water and phosphoric acid to form a slurry before acid leaching using acid and an oxidizing agent, the recovery rates of cobalt and nickel can be maintained at a high level while the contamination of copper can be reduced.

Claims

1. A recovery method for recovering cobalt and nickel from raw material powder containing cobalt, nickel, and copper, A slurrying step involves mixing raw material powders containing cobalt, nickel, and copper with water and phosphoric acid to obtain a slurry. An acid leaching step is performed in which the slurry obtained in the slurry formation step is mixed with an acid and an oxidizing agent to obtain an acid leaching solution. A neutralization step is performed by adding alkali to the acid leaching solution obtained in the acid leaching step, A recovery method characterized by including [a certain component].

2. The recovery method according to claim 1, wherein the raw material powder containing cobalt, nickel, and copper is a heat-treated product of a lithium-ion secondary battery.

3. The recovery method according to claim 1, wherein the raw material powder containing cobalt, nickel, and copper is a magnetic material obtained by classifying and wet magnetic separation of a heat-treated lithium-ion secondary battery.

4. The recovery method according to any one of claims 1 to 3, wherein in the slurrying step, phosphoric acid is added in an amount of 0.05 molar equivalents or more and 1.2 molar equivalents or less relative to the total molar amount of impurity metals other than valuable metals, including cobalt and nickel, in the raw material powder.

5. The recovery method according to any one of claims 1 to 3, wherein in the slurrying step, phosphoric acid is added in an amount of 0.4 molar equivalents or more and 1.2 molar equivalents or less relative to the total molar amount of impurity metals other than valuable metals, including cobalt and nickel, in the raw material powder.

6. The recovery method according to any one of claims 1 to 3, wherein the acid leaching step is performed under conditions where the pH is 1.0 or higher and 3.0 or lower, and the oxidation-reduction potential measured with respect to a silver-silver chloride electrode is -250 mV or higher and 0 mV or lower.

7. The recovery method according to any one of claims 1 to 3, wherein the neutralization step is performed under conditions that the pH is 3.0 or higher and 5.0 or lower, and the oxidation-reduction potential measured with respect to a silver-silver chloride electrode is 300 mV or higher and 550 mV or lower.

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