Methods for recovering valuable materials

Abstract

To provide a method for recovering a valuable substance with high safety.SOLUTION: A method for recovering valuable substance involves a reducing agent mixing step S150 in which a reducing agent is mixed with a valuable substance-containing material obtained from a secondary battery and a reducing step S190 in which the obtained mixture is heated and subjected to reduction treatment, and further involves a water treatment step S130 in which, prior to the reducing step S190, the valuable substance-containing material is brought into contact with a water-containing liquid.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for recovering valuable substances, and particularly to a method for recovering valuable substances from the recovered materials of secondary batteries.

Background Art

[0002] In recent years, with the increasing demand for mobile phones and computers, and the electrification of automobiles, the demand for secondary batteries such as nickel-hydrogen batteries and lithium-ion batteries has been rapidly increasing. Since these secondary batteries contain valuable metals such as cobalt, nickel, and manganese in the positive or negative electrodes, it is extremely important to recover valuable metals from used secondary batteries from the perspective of effective utilization of resources.

[0003] In addition, with the increasing demand for secondary batteries, the quantity of defective products of secondary batteries generated in the manufacturing process also tends to increase, and the recovery of valuable metals from these defective products is similarly extremely important.

[0004] Therefore, methods for recovering valuable metals from used secondary batteries and defective products of secondary batteries (these are collectively referred to as "secondary battery waste") have been studied. Broadly classified, the recovery methods include wet refining in which oxides of valuable metals contained in secondary battery waste are dissolved with a high-concentration strong acid to recover valuable metals (for example, Patent Document 1), and dry refining in which oxides of valuable metals contained in secondary battery waste are subjected to a heat reduction treatment and recovered as another valuable metal compound (for example, Patent Document 2). In Patent Document 2, it is described that in order to separate and recover Co and Li contained in the valuable metal compound (also called a calcined product) obtained by dry refining, the valuable metal compound is further treated with water.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] The recovery methods for valuable metals and valuable metal compounds (collectively referred to as "valuable substances") require safe and inexpensive recovery. In wet refining, the use of high concentrations of strong acids and neutralizing agents for their neutralization results in high costs for recovering valuable metals, and may also be insufficient in terms of safety. Because dry refining is relatively inexpensive, there has been a shift from wet refining to dry refining in recent years. However, when the inventors performed dry refining, they noticed that white smoke was generated during the heating and reduction process, and that this white smoke may be toxic.

[0007] Therefore, the object of the present invention is to provide a highly safe method for recovering valuable substances. [Means for solving the problem]

[0008] One aspect of the present invention is: A reducing agent mixing step in which a reducing agent is mixed with a valuable substance-containing material obtained from a secondary battery, The process includes a reduction step in which the obtained mixture is heated and reduced, Furthermore, the method for recovering valuable substances includes a water treatment step in which the valuable substance-containing material is brought into contact with a water-containing liquid prior to the reduction step.

[0009] Aspect 2 of the present invention is, The method for recovering a valuable substance according to Embodiment 1, wherein the liquid containing water is water or an acidic aqueous solution.

[0010] A third aspect of the present invention is: The water treatment step is a method for recovering a valuable substance according to embodiment 1 or 2, wherein the valuable substance-containing material is immersed in a liquid containing the water.

[0011] Aspect 4 of the present invention is The method for recovering valuable substances according to any one of Aspects 1 to 3 includes a flux mixing step of mixing a flux with the valuable substance-containing material before the reduction step.

[0012] Aspect 5 of the present invention is The method for recovering valuable substances according to Aspect 4, wherein the water treatment step is performed before the flux mixing step.

[0013] Aspect 6 of the present invention is The method for recovering valuable substances according to any one of Aspects 1 to 5, wherein the reducing agent includes one or more selected from the group consisting of a carbonaceous reducing agent and a reducing metal material.

[0014] Aspect 7 of the present invention is The method for recovering valuable substances according to any one of Aspects 1 to 6, wherein the reducing agent has an integrated volume of reducing agent particles with a particle size of 75 μm or less of 65% or more.

Advantages of the Invention

[0015] In an embodiment of the present invention, a method for recovering valuable substances with high safety can be provided.

Brief Description of the Drawings

[0016] [Figure 1] FIG. 1 is a flowchart for explaining the method for recovering valuable substances according to Embodiment 1. [Figure 2] FIG. 2 is a flowchart for explaining the method for recovering valuable substances according to Embodiment 2. [Figure 3] FIG. 3 is a flowchart for explaining the method for recovering valuable substances according to Embodiment 3. [Figure 4] FIG. 4 is a flowchart for explaining the method for recovering valuable substances according to Embodiment 4.

Modes for Carrying Out the Invention

[0017] When the inventors of the present invention were studying a method for recovering valuable substances from secondary battery waste by dry refining, they noticed that white smoke was generated during the heat reduction treatment in the conventional dry refining. And for the first time, they clarified that the white smoke contains toxic gases containing Li and F, which may have an adverse effect on the human body and damage the refractory of the furnace used in the heat reduction treatment. They earnestly studied to solve a new problem of providing a method for recovering valuable substances with less adverse effects on the human body and the furnace (that is, high safety). As a result, they first found that by bringing the secondary battery waste into contact with a liquid containing water before the heat reduction treatment, the generation of white smoke during the heat reduction treatment can be significantly reduced, and thus the recovery method according to the embodiment of the present invention was completed.

[0018] A method for recovering valuable substances according to an embodiment includes a reducing agent mixing step of mixing a reducing agent with a valuable substance-containing material obtained from secondary battery waste, and a reducing step of heating and reducing the obtained mixture, and further includes a water treatment step of bringing the valuable substance-containing material into contact with a liquid containing water (also referred to as "water-containing liquid" in this specification) before the reducing step. By bringing the valuable substance-containing material into contact with the water-containing liquid, Li and F contained in the valuable substance-containing material can be dissolved in water and removed. Therefore, in the subsequent reducing step, the generation of white smoke caused by Li and F can be suppressed.

[0019] Specific examples of the method for recovering valuable substances will be described in detail in Embodiments 1 to 4. In Embodiments 1 to 4, optionally, a step of mixing a flux (flux mixing step) can be included. Embodiments 1 to 4 are mainly different from each other in that the order of the reducing agent mixing step, the water treatment step, and the optionally performed flux mixing step is different.

[0020] Here, the flux mixing step basically may be performed before the reducing step of performing the heat reduction treatment. For example, the flux mixing step can be performed at any timing before the reducing agent mixing step, after the reducing agent mixing step, or simultaneously with the reducing agent mixing step.

[0021] Furthermore, the flux mixing process can be performed either before or after the water treatment process, but performing the flux mixing process after the water treatment process has the advantage of reducing the amount of wastewater generated during the water treatment process. Furthermore, depending on the type of flux (e.g., CaO and SiO2), it is preferable to perform the flux mixing step after the water treatment step. CaO may partially dissolve in water when it comes into contact with water. SiO2 can disperse in water due to its small particle size. Therefore, when using these fluxes, performing the flux mixing step before the water treatment step may cause the flux composition to change due to the influence of water. When using fluxes other than CaO and SiO2 (e.g., FeO, MgO, iron slag limestone, dolomite, and silica sand), contact with water has little effect. Therefore, the flux mixing process can be performed either before or after the water treatment process.

[0022] Embodiments 1 to 4 will be described below with reference to the drawings. While Embodiments 1 to 4 assume a flux mixing process, as mentioned above, the flux mixing process is optional and may be omitted.

[0023] (Embodiment 1) Figure 1 is a flowchart illustrating the method for recovering valuable substances according to Embodiment 1. The method for recovering valuable substances according to Embodiment 1 is as follows: The preparation process S110 for valuable material-containing materials, which involves preparing valuable material-containing materials from secondary battery waste, A water treatment step S130 in which a material containing valuable substances is brought into contact with a liquid containing water (hydrous liquid), A reducing agent mixing step S150 is performed in which a reducing agent is mixed into the valuable substance-containing material after water treatment. Flux mixing step S170 involves mixing flux into the valuable substance-containing material after water treatment, The process includes a reduction step S190 in which a mixture containing a valuable substance, a reducing agent, and a flux is heated and subjected to a reduction treatment.

[0024] In Embodiment 1, the reducing agent mixing step S150 and the flux mixing step S170 are collectively referred to as the "mixing step S140". In the mixing step S140, the reducing agent mixing step S150 and the flux mixing step S170 may be performed sequentially or simultaneously. Furthermore, the reducing agent mixing step S150 may be performed before or after the flux mixing step S170.

[0025] The following describes each step.

[0026] (Preparation process S110 for materials containing valuable substances) Secondary battery waste is processed, for example, by heating, crushing, sieving, and magnetic separation, to prepare a powdered material containing valuable substances (material containing valuable substances). The procedure for preparing a material containing valuable substances includes crushing the secondary battery waste into a powder. The resulting powder of secondary battery waste contains oxides of valuable metals such as Co, Ni, Mn, and Li, and compounds containing at least one of Li and F (e.g., LiF, AlF3, etc.). If necessary, the secondary battery waste may be heated before crushing to burn off combustible materials such as separators contained in the secondary battery waste. If necessary, after crushing, powdered elemental metals (e.g., Cu, Fe, Al, etc.) may be separated from the secondary battery waste powder by physical separation such as magnetic separation or air separation. In this way, a powdered material containing valuable substances is prepared.

[0027] (Water treatment process S130) Next, a liquid containing water (aqueous liquid) is prepared and brought into contact with the material containing the valuable substance. In this specification, this is referred to as "water treatment." Since compounds containing at least one of Li and F dissolve in the water contained in the aqueous liquid, Li and F can be separated and removed from the material containing the valuable substance by water treatment.

[0028] The aqueous liquid is preferably water or an acidic aqueous solution. Examples of acidic aqueous solutions include dilute hydrochloric acid, dilute sulfuric acid, acetic acid, carbonated water, and hydrogen peroxide. For example, the hydrogen ion concentration [H +An acidic aqueous solution with a concentration of 0.1 mol / L or less is preferred. Unlike conventional wet processes, the water treatment step in Embodiment 1 aims to dissolve water-soluble substances; therefore, highly concentrated strong acids with low water content are not suitable. Furthermore, the aqueous liquid may be a neutral aqueous solution such as saline solution (NaCl aqueous solution).

[0029] Methods for bringing a water-containing liquid into contact with a material containing valuable substances include, for example, immersing the material in the water-containing liquid or spraying or misting the material with the water-containing liquid. In particular, the method of immersing the material in the water-containing liquid is preferred, as it allows for efficient separation and removal of Li and F.

[0030] Subsequently, the valuable substance-containing material and the water-containing liquid are separated by a solid-liquid separation method such as filtration. The separated valuable substance-containing material may be used in the next process while still wet, or it may be dried before the next process. Drying can be carried out by natural drying, drying in a constant temperature bath, etc.

[0031] (Mixing process S140 (reducing agent mixing process S150, flux mixing process S170)) A reducing agent mixing step S150 is performed on the valuable substance-containing material after water treatment, and a flux mixing step S170 is performed on it, in which a reducing agent is mixed in. Figure 1 illustrates a case where the reducing agent mixing step S150 is performed first and the flux mixing step S170 is performed second, but the process is not limited to this. For example, the reducing agent mixing step S150 and the flux mixing step S170 may be performed simultaneously, or the flux mixing step S170 may be performed first and the reducing agent mixing step S150 may be performed second.

[0032] The reducing agent used in the reducing agent mixing step S150 is a reducing agent that can remove oxygen from oxides of valuable metals (especially oxides of Co and Ni) in the material containing valuable substances by being oxidized itself. The reducing agent is heated in the next reduction step S190, causing a reduction reaction with the oxides of valuable metals.

[0033] The reducing agent preferably includes one or more selected from the group consisting of carbonaceous reducing agents and reducing metal materials. Examples of carbonaceous reducing agents include coal (such as bituminous coal and lignite), wood charcoal, and bamboo charcoal. Suitable metal reducing agents include active metals that can reduce Ni and Co, that is, active metals with a higher ionization tendency than Ni and Co. Specifically, metallic Al and metallic Si are preferred metal reducing agents.

[0034] The amount of reducing agent should be sufficient to adequately reduce the oxides of valuable metals in the material containing valuable substances. For example, when the material containing valuable substances is considered to be 100% by mass, the amount of reducing agent should be 5% by mass or more. If the amount of reducing agent is excessive, the amount of valuable metal recovered per unit mass of raw materials (including the material containing valuable substances and the reducing agent) will decrease, resulting in poor economic efficiency. Therefore, preferably, when the material containing valuable substances is considered to be 100% by mass, the amount of reducing agent should be 25% by mass or less. One type of reducing agent may be used, or two or more types may be mixed and used.

[0035] The reducing agent is preferably in powder form, and in particular, it is preferable that the cumulative volume of reducing agent particles with a particle size of 75 μm or less is 65% or more. This makes it easier to homogeneously mix with the powdered valuable substance-containing material. The cumulative volume of reducing agent particles with a particle size of 75 μm or less is measured by laser diffraction and scattering. Reducing agents with such a particle size distribution can be prepared by grinding coarse reducing agents in a ball mill.

[0036] In the flux mixing step S170, a flux is mixed in to melt the recovered material. Fluxes known in this art can be used, such as CaO, SiO2, FeO, MgO, steel slag limestone, dolomite, and silica sand.

[0037] The mixture obtained in mixing step S140 includes a valuable substance-containing material, a reducing agent, and a flux.

[0038] (Reduction process S190) In the reduction step S190, the mixture obtained in the mixing step S140 (i.e., the mixture containing the valuable substance, reducing agent, and flux) is heated and melted to reduce the oxides of the valuable metals contained in the valuable substance (reduction treatment). The heating temperature for the reduction treatment should be such that the valuable substance melts and the reducing agent undergoes a reduction reaction with the oxides of the valuable metals, and can be appropriately set depending on the type of reducing agent, the type of oxide to be treated, etc. The heating time should be such that the reduction reaction between the reducing agent and the oxides of the valuable metals proceeds sufficiently at the predetermined heating temperature, and can be appropriately set depending on the heating temperature, the type of reducing agent, the type of oxide to be treated, etc. As a typical example, when reducing oxides of Co and Ni using a carbonaceous reducing agent, the heating temperature can be 1400°C to 1650°C, and the heating time can be 60 minutes or less. The heating temperature is the temperature of the crucible (heating element). The crucible temperature is measured using a thermocouple attached to the surface of the crucible.

[0039] In conventional dry refining, heating and reducing a material containing valuable substances produced a large amount of white smoke. The inventors hypothesized that this white smoke was caused by the volatilization of LiF and AlF3 contained in the material containing valuable substances, and by the evaporation of compounds (such as SiF4) generated by heating during the reduction process. They then discovered that by treating the material containing valuable substances with water before the reduction process to remove Li and F, the generation of white smoke during the reduction process could be significantly reduced.

[0040] Since gases containing Li and F are toxic, suppressing the generation of white smoke during the reduction process can reduce adverse effects on human health and the heating furnace performing the reduction. Furthermore, since the reduction process is carried out at high temperatures, indirect heating by radiant heat is generally dominant. When white smoke is generated in the furnace, heat is absorbed by the smoke, reducing heating efficiency. In Embodiment 1, the generation of white smoke can be suppressed by the water treatment process of the material containing valuable substances, thereby improving heating efficiency during the reduction process.

[0041] (Embodiment 2) Embodiment 2 differs from Embodiment 1 in that the reducing agent mixing step is performed before the water treatment step. The method for recovering valuable substances according to Embodiment 2 will be explained, focusing on the differences from Embodiment 1, with reference to the flowchart in Figure 2.

[0042] The method for recovering valuable substances according to Embodiment 2 is: The preparation process S210 for materials containing valuable substances, which involves preparing materials containing valuable substances from secondary battery waste, A reducing agent mixing step S220 is performed in which a reducing agent is mixed with a material containing valuable substances, A water treatment step S230 involves bringing a mixture containing a valuable substance and a reducing agent into contact with a water-containing liquid (hydrous liquid), Flux mixing step S270 involves mixing flux into the mixture after water treatment, The process includes a reduction step S290 in which a mixture containing a valuable substance, a reducing agent, and a flux is heated and subjected to a reduction treatment.

[0043] (Preparation process S210 for materials containing valuable substances) The preparation step S210 for the material containing valuable substances is the same as the "preparation step S110 for the material containing valuable substances" in Embodiment 1, so the details are omitted.

[0044] (Reducing agent mixing step S220) In the reducing agent mixing step S220, the reducing agent is mixed with the material containing valuable substances. Embodiment 2 differs from Embodiment 1 in that the reducing agent mixing step S220 is performed before the water treatment step, and the reducing agent mixing step and the flux mixing step are performed separately. Otherwise, it is the same as the "reducing agent mixing step S150" in Embodiment 1, so details are omitted.

[0045] (Water treatment process S230) The mixture obtained in the reducing agent mixing step S220, which contains the valuable substance-containing material and the reducing agent, is brought into contact with an aqueous liquid and subjected to water treatment. Through water treatment, Li and F can be separated and removed from the valuable substance-containing material contained in the mixture. The rest of the process is the same as in the "water treatment process S130" of Embodiment 1, so the details will be omitted.

[0046] (Flux mixing process S270) After the water treatment process S230, flux is further mixed into the mixture containing the valuable substance-containing material and the reducing agent (flux mixing process S270). The flux mixing step S270 is the same as the "flux mixing step S170" in Embodiment 1, so details will be omitted.

[0047] (Reduction process S290) In the reduction step S290, a mixture containing a valuable substance, a reducing agent, and a flux is subjected to reduction treatment. The reduction step S290 is the same as the "reduction step S190" in Embodiment 1, so the details are omitted.

[0048] The method for recovering valuable substances according to Embodiment 2, similar to Embodiment 1, involves treating the valuable substance-containing material with water before the reduction process to remove Li and F, thereby significantly reducing the generation of white smoke during the reduction process. This suppresses adverse effects on the human body and the heating furnace performing the reduction process. Furthermore, suppressing the generation of white smoke improves the heating efficiency during the reduction process.

[0049] (Embodiment 3) Embodiment 3 differs from Embodiment 1 in that the mixing process (reducing agent mixing process and flux mixing process) is performed before the water treatment process. The method for recovering valuable substances according to Embodiment 3 will be explained, focusing on the differences from Embodiment 1, with reference to the flowchart in Figure 3.

[0050] The method for recovering valuable substances according to Embodiment 3 is: The preparation process S310 for valuable material-containing materials, which involves preparing valuable material-containing materials from secondary battery waste, A reducing agent mixing step S350 is performed in which a reducing agent is mixed with a material containing valuable substances, Flux mixing step S370 involves mixing flux into a material containing valuable substances, A water treatment step S380 involves bringing a mixture containing a valuable substance, a reducing agent, and a flux into contact with a water-containing liquid (hydrous liquid), The process includes a reduction step S390 in which the mixture after water treatment is heated and subjected to reduction treatment.

[0051] In Embodiment 3, as in Embodiment 1, the reducing agent mixing step S350 and the flux mixing step S370 are collectively referred to as the "mixing step S340".

[0052] (Preparation process for materials containing valuable substances S310) The preparation step S310 for the material containing valuable substances is the same as the "preparation step S110 for the material containing valuable substances" in Embodiment 1, so the details are omitted.

[0053] (Mixing process S340 (reducing agent mixing process S350, flux mixing process S370)) A reducing agent mixing step S350 is performed on the material containing valuable substances, and a flux mixing step S370 is performed on it, in which a reducing agent is mixed in. Embodiment 3 differs from Embodiment 1 in that the mixing step S340 is performed before the water treatment step. Otherwise, it is the same as the "mixing step S140" in Embodiment 1, so details are omitted. Furthermore, while Figure 3 illustrates a case where the reducing agent mixing step S350 is performed first and the flux mixing step S370 is performed later, the invention is not limited to this, as is the case with Embodiment 1.

[0054] (Water treatment process S380) The mixture obtained in mixing step S340 (i.e., a mixture containing valuable substances, a reducing agent, and a flux) is subjected to water treatment by contacting it with an aqueous liquid. Water treatment allows for the separation and removal of Li and F from the valuable substances contained in the mixture. The rest of the process is the same as in the "water treatment process S130" of Embodiment 1, so the details will be omitted.

[0055] (Reduction process S390) In the reduction step S390, the mixture after the water treatment step S380 is subjected to reduction treatment. The reduction step S390 is the same as the "reduction step S190" in Embodiment 1, so the details are omitted.

[0056] The method for recovering valuable substances according to Embodiment 3, similar to Embodiments 1 and 2, removes Li and F by water treatment of the valuable substance-containing material before the reduction process, thereby significantly reducing the generation of white smoke during the reduction process. This suppresses adverse effects on the human body and the heating furnace performing the reduction process. Furthermore, since the generation of white smoke is suppressed, the heating efficiency during the reduction process can also be improved.

[0057] (Embodiment 4) Embodiment 4 differs from Embodiment 1 in that the flux mixing process is performed before the water treatment process. The method for recovering valuable substances according to Embodiment 4 will be explained, focusing on the differences from Embodiment 1, with reference to the flowchart in Figure 4.

[0058] The method for recovering valuable substances according to Embodiment 4 is: The preparation process S410 for valuable material-containing materials, which involves preparing valuable material-containing materials from secondary battery waste, Flux mixing step S420 involves mixing flux into a material containing valuable substances, A water treatment step S430 involves bringing a mixture containing a valuable substance and flux into contact with a water-containing liquid (hydrous liquid), A reducing agent mixing step S450 is performed in which a reducing agent is mixed into the mixture after water treatment. The process includes a reduction step S490 in which a mixture containing a valuable substance, a reducing agent, and a flux is heated and subjected to a reduction treatment. The following describes each step.

[0059] (Preparation process for materials containing valuable substances S410) The preparation step S410 for the material containing valuable substances is the same as the "preparation step S110 for the material containing valuable substances" in Embodiment 1, so the details are omitted.

[0060] (Flux mixing process S420) In the flux mixing process S420, flux is mixed with the material containing valuable substances. Embodiment 4 differs from Embodiment 1 in that the flux mixing step S420 is performed before the water treatment step, and the reducing agent mixing step and the flux mixing step are performed separately. Otherwise, it is the same as the "flux mixing step S170" in Embodiment 1, so details are omitted.

[0061] (Water treatment process S430) The mixture obtained in the flux mixing step S420, which contains the valuable substance-containing material and flux, is subjected to water treatment by contacting it with an aqueous liquid. Through water treatment, Li and F can be separated and removed from the valuable substance-containing material contained in the mixture. The rest of the process is the same as in the "water treatment process S130" of Embodiment 1, so the details will be omitted.

[0062] (Reducing agent mixing process S450) After the water treatment process S430, a reducing agent is further mixed into the mixture containing the valuable substance-containing material and flux (reducing agent mixing process S450). The reducing agent mixing step S450 is the same as the "reducing agent mixing step S150" in Embodiment 1, so the details are omitted.

[0063] (Reduction process S490) In the reduction process S490, a mixture containing a valuable substance, a reducing agent, and a flux is subjected to reduction treatment. The reduction step S490 is the same as the "reduction step S190" in Embodiment 1, so the details are omitted.

[0064] The method for recovering valuable substances according to Embodiment 4, similar to Embodiments 1 to 3, removes Li and F by water treatment of the valuable substance-containing material before the reduction process, thereby significantly reducing the generation of white smoke during the reduction process. This suppresses adverse effects on the human body and the heating furnace performing the reduction process. Furthermore, since the generation of white smoke is suppressed, the heating efficiency during the reduction process can also be improved. [Examples]

[0065] (sample material) A powder obtained by heating, crushing, and physically separating lithium-ion batteries was prepared as a test material and used in Examples 1 and 2.

[0066] [Example 1] Invention Example 1-1 and Comparative Example 1-1 were carried out in the following manner.

[0067] (Example of Invention 1-1) Samples of Invention Example 1-1 were prepared by performing water treatment (water immersion), drying, mixing, and reduction treatment 1-4 according to the following procedures 1-7. 1. (Water immersion) 20 g of powdered test material was immersed in 500 ml of distilled water and stirred with a stirrer for 3 hours. The test material was then recovered by filtration using filter paper. 2. (Drying) After immersion in water, the test material was dried in a constant temperature bath at 100°C for half a day. 3. (Mixing) 8.8 g of the dried test material was mixed with 0.6 g of charcoal, which had been ground to an appropriate particle size as a reducing agent. Further mixing was done with 0.3 g of CaCO3 reagent and 0.3 g of SiO2 reagent. The resulting mixture was placed in a crucible and set up in a high-frequency heating furnace. 4. (Reduction treatment 1) After evacuating the furnace to below 50 Pa, N2 purging was performed and the pressure was set to below atmospheric pressure. 5. (Reduction Treatment 2) The crucible was heated to a temperature of 1400°C at a heating rate of 100°C / min and held at 1400°C for 10 minutes. The crucible temperature was measured using a thermocouple attached to the surface of the crucible. 6. (Reduction treatment 3) The high-frequency current was turned OFF to stop heating, and the sample was cooled. 7. (Reduction Treatment 4) Once the crucible temperature fell below 300°C, the furnace was evacuated to below 50 Pa, followed by air replacement. The crucible was removed from the furnace, and the sample inside was collected.

[0068] (Comparative Example 1-1) In Comparative Example 1-1, steps 1 (water immersion) and 2 (drying) of Experimental Example 1-1 were omitted, and the sample was prepared by performing steps 3-7.

[0069] For Invention Example 1-1 and Comparative Example 1-1, ICP emission spectroscopy analysis was performed on (i) the test material, the test material before step 3 (mixing) ("(ii) test material before reduction treatment"), and the sample after step 7 (reduction treatment 4) ("(iii) sample after reduction treatment") using an ICP emission spectrometer SPS3500DD (manufactured by SII Corporation) to measure the content of Li and F. The measurement results are shown in Table 1.

[0070] In Comparative Example 1-1, steps 1 and 2 were not performed, so (i) the test material and (ii) the test material before reduction treatment were identical. Therefore, the results of their ICP emission spectroscopy analysis (Li and F content) were assumed to be identical (see Table 1). The difference was calculated by subtracting the total amount of Li and F in the sample after reduction treatment from the total amount of Li and F in the sample before reduction treatment (ii) and recorded in Table 1 under "(iv) Total decrease in Li and F after reduction treatment". The "volatility" in Table 1 was calculated using the following formula. Volatility (%) = ((iv) Total decrease in Li and F after reduction treatment (g)) / ((i) Total amount of Li and F in the test material (g)) × 100

[0071] [Table 1]

[0072] From the results in Table 1, in Invention Example 1-1, where Procedure 1 (water immersion) was performed, the content of both Li and F in "(ii) the test material before reduction treatment" was lower, and the "(iv) total decrease in Li and F after reduction treatment" (volatilization amount) was lower, as was the volatility rate. Furthermore, a glass window was installed on the top of the furnace, and a video camera was placed outside the furnace. The inside of the furnace was recorded through the glass window, and the smoke generation inside the furnace during dry refining was observed. In Invention Example 1-1, the amount of smoke generated was clearly less than in Comparative Example 1-1.

[0073] [Example 2] Invention Examples 2-1 and 2-2 were carried out in the following manner.

[0074] (Examples of Inventions 2-1, 2-2) The samples were treated with water (immersed in aqueous solution) according to steps 8 and 9 below, and the filtrate was dried. 8. (Immersion in aqueous solution) 150 g of the powdered test material was immersed in 2 L of the immersion solution (acidic aqueous solution) shown in Table 2, stirred with a stirrer for 3 hours, and then filtered using filter paper to collect the filtrate. 9. (Drying) 1.5 L of the filtrate was concentrated to approximately 50 mL using an evaporator, the concentrated liquid was transferred to an evaporating dish and heated on a hot plate to dry it, and then dried at 105°C until the weight became constant to obtain a dry product.

[0075] After pretreatment of the dried material (decomposition of the dried material with aqua regia), ICP emission spectroscopy analysis was performed using an ICP emission spectrometer ICPS-8100 (Shimadzu Corporation) to measure the Li and F content in the dried material. The measurement results are shown in Table 2.

[0076] [Table 2]

[0077] As shown in Table 2, both Invention Example 2-1 and Invention Example 2-2 contained Li and F in the dried material. This confirms that Li and F leached out from the test material by performing Step 8 (immersion in aqueous solution). Even when the immersion solution is an acidic aqueous solution, the content of Li and F in the test material can be reduced by water treatment, so it is thought that the amount of smoke generated when dry refining is performed afterward can be suppressed.

Claims

1. A preparation process for a valuable material containing secondary battery waste containing Li and / or F, which includes crushing the battery waste into powder, A reducing agent mixing step in which a reducing agent is mixed with the aforementioned valuable substance-containing material, The process includes a reduction step in which the obtained mixture is heated and reduced, Furthermore, a method for recovering a valuable substance, comprising a water treatment step prior to the reducing agent mixing step and the reduction step, in which the valuable substance-containing material is brought into contact with a liquid consisting of one or more selected from the group consisting of dilute hydrochloric acid, acetic acid, carbonated water, hydrogen peroxide solution, and saline solution.

2. The method for recovering a valuable substance according to claim 1, wherein the liquid is an acidic aqueous solution.

3. The method for recovering a valuable substance according to claim 1 or 2, wherein the water treatment step is performed by immersing the valuable substance-containing material in the liquid.

4. A method for recovering a valuable substance according to any one of claims 1 to 3, further comprising a flux mixing step of mixing a flux with the valuable substance-containing material prior to the reduction step.

5. The method for recovering a valuable substance according to claim 4, wherein the water treatment step is performed before the flux mixing step.

6. The method for recovering a valuable substance according to any one of claims 1 to 5, wherein the reducing agent comprises one or more selected from the group consisting of carbonaceous reducing agents and reducing metal materials.

7. The method for recovering a valuable substance according to any one of claims 1 to 6, wherein the reducing agent comprises reducing agent particles with a particle size of 75 μm or less, with an accumulated volume of 65% or more.

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