VALUABLE METAL RECOVERY METHOD AND RECOVERY APPARATUS

Abstract

A valuable metal recovery method includes: recovering a battery slag from lithium ion battery waste; adding an acid to the battery slag; adding a sulfur compound the leachate; filtering the first processed product to obtain a first processed filtrate; adding a sulfur compound to the first processed filtrate; filtering the second processed product to obtain a second processed filtrate; adding calcium hydroxide to the second processed filtrate; filtering the third processed product to obtain a third processed filtrate; adding sodium carbonate to the third processed filtrate; filtering the processed product; heating the fourth processed filtrate; blowing carbon dioxide or adding a carbonate; and filtering the processed product, wherein a pH of the second processed product is higher than a pH of the first processed product, and a pH of the third processed product is higher than the pH of the second processed product.

Claims

1. A valuable metal recovery method comprising: a screening step of screening a battery slag from lithium ion battery waste; an acid leaching step of adding an acid to the battery slag to produce a leachate; a first addition step of adding a first sulfur compound containing a Na content as a first additive to the leachate to produce a first processed product; a first filtration step of filtering the first processed product to be separated into a first processed filtrate and a first processed residue containing a Cu content; a second addition step of adding a second sulfur compound containing a Na content as a second additive to the first processed filtrate to produce a second processed product; a second filtration step of filtering the second processed product to be separated into a second processed filtrate and a second processed residue containing a Co content and/or a Ni content; a third addition step of adding calcium hydroxide as a third additive to the second processed filtrate to produce a third processed product; a third filtration step of filtering the third processed product to be separated into a third processed filtrate containing a Li content and a third processed residue; a fourth addition step of adding sodium carbonate as a fourth additive to the third processed filtrate to produce a fourth processed product; a fourth filtration step of filtering the fourth processed product to be separated into a fourth processed filtrate and a fourth processed residue containing a Ca content; a heating step of heating the fourth processed filtrate; a fifth addition step of blowing carbon dioxide into the heated fourth processed filtrate or adding a carbonate to the heated fourth processed filtrate to produce a fifth processed product; and a fifth filtration step of filtering the fifth processed product to be separated into a fifth processed filtrate containing a Na content and a fifth processed residue containing a Li content, wherein a pH of the second processed product is higher than a pH of the first processed product, and a pH of the third processed product is higher than the pH of the second processed product.

2. The valuable metal recovery method according to claim 1, wherein in the acid leaching step, sulfuric acid, which is the acid, and hydrogen peroxide are added to the battery slag.

3. The valuable metal recovery method according to claim 1 comprising: a washing step of washing the third processed residue with an alkaline aqueous solution to produce a washing product; and a post-washing filtration step of filtering the washing product to be separated into a washing filtrate containing the Li content and a washed residue, wherein in the fourth addition step, the fourth processed product is produced from the third processed filtrate and the washing filtrate.

4. The valuable metal recovery method according to claim 2, wherein the battery slag includes a positive-electrode active material containing Ni and/or Co and a negative-electrode active material containing graphite, the method further comprises a sintering step of sintering the battery slag and oxidizing the graphite to produce carbon dioxide, and in the acid leaching step, the sulfuric acid is added to the sintered battery slag.

5. A valuable metal recovery apparatus comprising: a screening device configured to recover a battery slag from lithium ion battery waste; an acid leaching device configured to add an acid to the battery slag to produce a leachate; a first addition device configured to add a first sulfur compound containing a Na content as a first additive to the leachate to produce a first processed product; a first filtration device configured to filter the first processed product to be separated into a first processed filtrate and a first processed residue containing a Cu content; a second addition device configured to add a second sulfur compound containing a Na content as a second additive to the first processed filtrate to produce a second processed product; a second filtration device configured to filter the second processed product to be separated into a second processed filtrate and a second processed residue containing a Co content and/or a Ni content; a third addition device configured to add calcium hydroxide as a third additive to the second processed filtrate to produce a third processed product; a third filtration device configured to filter the third processed product to be separated into a third processed filtrate containing a Li content and a third processed residue; a fourth addition device configured to add sodium carbonate as a fourth additive to the third processed filtrate to produce a fourth processed product; a fourth filtration device configured to filter the fourth processed product to be separated into a fourth processed filtrate and a fourth processed residue containing a Ca content; a heating device configured to heat the fourth processed filtrate; a fifth addition device configured to blow carbon dioxide into the heated fourth processed filtrate or add a carbonate to the heated fourth processed filtrate to produce a fifth processed product; and a fifth filtration device configured to filter the fifth processed product to be separated into a fifth processed filtrate containing a Na content and a fifth processed residue containing a Li content, wherein a pH of the second processed product is higher than a pH of the first processed product, and a pH of the third processed product is higher than the pH of the second processed product.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0023] FIG. 1 is an explanatory diagram showing a procedure of a valuable metal recovery method according to an embodiment of the present invention.

[0024] FIG. 2 is an explanatory diagram showing a valuable metal recovery apparatus according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

[0025] A valuable metal recovery method according to an embodiment of the present invention will be described. This recovery method has been applied to the treatment for a so-called lithium ion battery. FIG. 1 is an explanatory diagram of showing a procedure of this recovery method. FIG. 2 is schematically showing a valuable metal recovery apparatus 100 for carrying out this recovery method.

[0026] As shown in FIG. 1, this recovery method includes a heat treatment step S1, a crushing step S2, a screening step S3, an acid leaching step S4, a first addition step S5, a first filtration step S6, a second addition step S7, a second filtration step S8, a third addition step S9, a third filtration step S10, a fourth addition step S11, a fourth filtration step S12, a heating step S13, a fifth addition step S14, and a fifth filtration step S15.

[0027] The heat treatment step S1 is a step of heat-treating a lithium ion battery waste W1 by a heat treatment device 1 (FIG. 2). The heat treatment is performed in a condition of, for example, a superheated steam and/or nitrogen atmosphere at 500? C. for 1 hour. In this step, an electrolytic solution contained in the waste W1 can be heated and volatilized to detoxify the waste W1. The waste W1 contains metals such as a Li content, a Ni content, a Co content, a Mn content, an A1 content, and a Cu content. In the heat treatment step S1, the waste W1 is heat-treated, thereby obtaining a waste W2.

[0028] The crushing step S2 is a step of crushing the waste W2 by a crushing device 2 (FIG. 2) to produce a crushed product C. For example, a twin-screw crusher and a hammer crusher can be used as the crushing device 2.

[0029] The screening step S3 is a step of removing metal pieces I from the crushed product C and screening the battery slag M by using a screening device 3 (FIG. 2). A sieve such as a vibration sieve can be used as the screening device 3. When the sieve is used, for example, a sieve having a sieve mesh of about 0.5 mm is used, and the content that has passed through the sieve is the battery slag M and the remaining content in the sieve is impurities I. The battery slag M is mixed powder having a positive-electrode active material and a negative-electrode active material contained in the waste W1. The metal pieces I have aluminum pieces and copper pieces included in the waste W1.

[0030] In the acid leaching step S4, an acid S is added to the battery slag M in the acid leaching device 4 (FIG. 2), thereby leaching metals (Li content, Ni content, Co content, Mn content, A1 content, Cu content, and other metal contents) contained in the battery slag M into the acid S. In the acid leaching step S4, a leachate E which is a mixed solution of the battery slag M and the acid S is produced. For example, a mixture of sulfuric acid and hydrogen peroxide can be used as the acid S.

[0031] The first addition step S5 is a step of adding a first additive A1 (first sulfur compound) to the leachate E in the first addition device 5 (FIG. 2) to produce Cu sulfide contained in the leachate E. In the first addition step S5, a first processed product P1, which is a mixture of the leachate E and the first additive A1, is produced. As the first additive A1, the sulfur compound containing a Na content can be used, and specifically, sodium hydrogen sulfide can be used. Regarding the addition of the first additive A1, a pH of the first processed product P1 is preferably 1 or less, and the oxidation-reduction potential (ORP) is preferably 0 mV (vs. Ag/AgCl) or less.

[0032] The first filtration step S6 is a step of filtering, in the first filtration device 6 (FIG. 2), the first processed product P1 composed of a liquid component and a solid component to be separated into a first processed filtrate F1, which is a liquid component, and a first processed residue R1, which is a solid component. The first processed residue R1 contains Cu sulfide. The first processed filtrate F1 contains a Li content, a Ni content, a Co content, a Mn content, an A1 content, and a Na content (the Na content is derived from the first additive A1). The first processed filtrate F1 contains almost no Cu content (this point will be described in the test example described later). In this manner, the Li content is separated from the Cu content.

[0033] The second addition step S7 is a step of adding a second additive A2 (second sulfur compound) to the first processed filtrate F1 in the second addition device 7 (FIG. 2) to produce sulfides of the Ni content and the Co content contained in the first processed filtrate F1. In the second addition step S7, a second processed product P2, which is a mixture of the first processed filtrate F1 and the second additive A2, is produced. As the second additive A2, the sulfur compound containing a Na content can be used, and specifically, sodium hydrogen sulfide can be used. Regarding the addition of the second additive A2, a pH of the second processed product P2 is preferably 2 or more and 3 or less (which is more than the pH of the processed product P1), and the oxidation-reduction potential (ORP) is preferably ?420 mV (vs. Ag/AgCl) or less.

[0034] The second filtration step S8 is a step of filtering, in the second filtration device 8 (FIG. 2), the second processed product P2 composed of a liquid component and a solid component to be separated into a second processed filtrate F2, which is a liquid component, and a second processed residue R2, which is a solid component. The second processed residue R2 contains sulfides of a Ni content and a Co content. The second processed filtrate F2 contains a Li content, a Mn content, an A1 content, and a Na content (derived from the first additive A1 and the second additive A2). The second processed filtrate F2 contains almost no Ni content and Co content (this point will be described in the test example described later). In this manner, the Li content is separated from the Ni content and the Co content.

[0035] The third addition step S9 is a step of adding a third additive A3 to the second processed filtrate F2 in the third addition device 9 (FIG. 2) to produce hydroxides, such as the A1 content and the Mn content contained in the second processed filtrate F2. In the third addition step S9, a third processed product P3, which is a mixture of the second processed filtrate F2 and the third additive A3, is produced. Calcium hydroxide is used as the third additive A3. Regarding the addition of the third additive A3, a pH of the third processed product P3 is preferably 10 or more (more than the pH of the second processed product P2).

[0036] The third filtration step S10 is a step of filtering, in the third filtration device 10 (FIG. 2), the third processed product P3 composed of a liquid component and a solid component to be separated into a third processed filtrate F3, which is a liquid component, and a third processed residue R3, which is a solid component. The third processed residue R3 contains hydroxides of an A1 content and a Mn content. The third processed filtrate F3 contains a Li content, a Na content, and a Ca content (derived from the third additive A3). The third processed filtrate F3 contains almost no A1 content and Mn content (this point will be described in the test example described later). In this manner, the Li content is separated from the A1 content and the Mn content.

[0037] The fourth addition step S11 is a step of adding a fourth additive A4 to the third processed filtrate F3 in the fourth addition device 11 (FIG. 2) to precipitate the Ca content without precipitating the Li content contained in the third processed filtrate F3. In the fourth addition step S11, a fourth processed product P4, which is a mixture of the third processed filtrate F3 and the fourth additive A4, is produced. As the fourth additive A4, either sodium carbonate or sodium carbonate hydrate is used, or a combination thereof is used.

[0038] The fourth filtration step S12 is a step of filtering, by the fourth filtration device 12 (FIG. 2), the fourth processed product P4 composed of a liquid component and a solid component to be separated into a fourth processed filtrate F4, which is a liquid component, and a fourth processed residue R4, which is a solid component. The fourth processed residue R4 contains carbonate of a Ca content, and the fourth processed filtrate F4 contains a Li content and a Na content. In this step, the Li content is separated from the Ca content. In the fourth filtration step S12, in order to prevent the Li content from being carbonate together with the Ca content and discharged together with the Ca content as the fourth processed residue R4, it is preferable to separate the fourth processed product P4 into the fourth processed filtrate F4 and the fourth processed residue R4 while maintaining the temperature lower than 50? C. (preferably 20? C. or higher and 30? C. or lower).

[0039] The heating step S13 is a step of heating the fourth processed filtrate F4 to 50? C. or higher (preferably 60? C. or higher and 80? C. or lower) by the heating device 13 (FIG. 2) to produce a high-temperature filtrate H.

[0040] The fifth addition step S14 is a step of blowing, by the fifth addition device 14 (FIG. 2), carbon dioxide G into the high-temperature filtrate H and carbonating the Li content contained in the high-temperature filtrate H. In the fifth addition step S14, a fifth processed product P5, which is a mixture of the high-temperature filtrate H and the carbon dioxide G, is produced. Instead of blowing the carbon dioxide G into the high-temperature filtrate H, or while blowing the carbon dioxide G into the high-temperature filtrate H, carbonate (for example, sodium hydrogen carbonate or sodium carbonate hydrate) can be added to the high-temperature filtrate H.

[0041] The fifth filtration step S15 is a step of filtering, by the fifth filtration device 15 (FIG. 2), the fifth processed product P5 composed of a liquid component and a solid component to be separated into a fifth processed filtrate F5, which is a liquid component, and a fifth processed residue R5, which is a solid component. The fifth processed residue R5 contains carbonate of a Li content, and the fifth processed filtrate F5 contains a Na content. In this step, the Li content is separated from the Na content. In the fifth filtration step S15, for the purpose of carbonating the Li content, it is preferable to separate the fifth processed product P5 into the fifth processed filtrate F5 and the fifth processed residue R5 while maintaining the temperature 50? C. or higher (preferably 60? C. or higher and 80? C. or lower).

[0042] Next, the test example with the valuable metal recovery method and the recovery apparatus according to the embodiment of the present invention will be described. Hereinafter, each step in the test example will be described in correspondence with the above-described embodiment. In addition, in the following, matters that are not particularly described are the same as those of the above-described embodiment.

[0043] (Heat Treatment Step to Acid Leaching Step)

[0044] 100 ml of sulfuric acid (concentration of 2 mol/l) and 5 ml of a hydrogen peroxide solution (concentration of 30% by mass) are added to 14.5 g of a battery slag recovered from a lithium ion secondary battery waste to produce a leachate. The leachate was heated to 60? C. and stirred for 4 hours. Then, the leachate was allowed to cool to room temperature.

[0045] (First Addition Step)

[0046] A NaSH aqueous solution (concentration of 200 g/l) was added to the leachate that had been allowed to cool to room temperature to produce a first processed product. The NaSH aqueous solution was added until an oxidation-reduction potential (ORP) of the first processed product reached 0 mV (vs. Ag/AgCl). Next, a NaOH aqueous solution (concentration of 25% by mass) was added to the first processed product. The NaOH aqueous solution was added until the pH of the first processed product was adjusted to about 3.5.

[0047] (First Filtration Step)

[0048] The first processed product to which a NaOH aqueous solution was added was filtered to be separated into a first processed filtrate and a first processed residue.

[0049] (Second Addition Step)

[0050] A NaSH aqueous solution (concentration of 200 g/l) was added to the first processed filtrate to produce a second processed product. The addition of a NaSH aqueous solution was carried out such that an oxidation-reduction potential (ORP) of the second processed product reached ?420 mV.

[0051] (Second Filtration Step)

[0052] The second processed product was filtered to be separated into a second processed filtrate and a second processed residue.

[0053] (Third Addition Step)

[0054] An aqueous calcium hydroxide solution was added to the second processed filtrate to produce a third processed product. The addition of the aqueous calcium hydroxide solution was carried out such that the pH of the third processed product was 10.0 or more.

[0055] (Third Filtration Step)

[0056] The third processed product was filtered to be separated into a third processed filtrate and a third processed residue.

TABLE-US-00001 TABLE 1 Concentration of each component (g/l) Ni Co Mn Li Al Cu Fe Mg Zn Leachate 12.72 13.79 12.53 6.91 3.78 0.98 0.12 0.01 0.10 First processed filtrate 10.29 11.09 10.12 5.62 2.20 <0.01 0.10 <0.01 0.08 Second processed filtrate 0.05 0.07 9.33 4.17 1.71 <0.01 0.04 0.03 <0.01 Third processed filtrate <0.01 <0.01 <0.01 4.14 <0.01 <0.01 <0.01 0.00 <0.01

[0057] In Table 1, chemical compositions of the leachate, the first processed filtrate, the second processed filtrate, and the third processed filtrate, which were measured by inductively coupled plasma (ICP) optical emission spectroscopy, were shown. As shown in Table 1, the leachate contains large amounts of a Ni content, a Co content, a Mn content, an Al content, a Cu content, a Fe content, a Mg content, and a Zn content in addition to the Li content. In the first processed filtrate, the concentration of the Cu content is reduced to less than 0.01 g/l. In the second processed filtrate, the concentrations of the Ni content and the Co content are further reduced to less than 0.10 g/l. In the third processed filtrate, while the concentration of the Li content was 4.14 g/l, the concentrations of the metals other than the Li content (Ni content, Co content, Mn content, Al content, Cu content, Fe content, Mg content, and Zn content) are all reduced to less than 0.01 g/l.

[0058] As described above, according to the above-described embodiment, by providing the heat treatment step S1 to the third filtration step S10 (or the heat treatment device 1 to the third filtration device 10), the Li content contained in the lithium ion battery waste W1 can be separated from other metals and efficiently recovered.

[0059] In addition, according to the above-described embodiment, by providing the fourth addition step S11 to the fifth filtration step S15, the Li content contained in the lithium ion battery waste W1 can be separated from the Na content contained in the first additive A1, the second additive A2, and the fourth additive A4, and the Ca content contained in the third additive A3, and can be recovered.

[0060] Furthermore, according to the above-described embodiment, the Cu content can be recovered as the first processed residue R1, the Ni content and the Co content can be recovered as the second processed residue R2, and the A1 content and the Mn content can be recovered as the third processed residue R3. Accordingly, these recovered metals can be effectively used. In particular, in the acid leaching step S4, by adding sulfuric acid and hydrogen peroxide as the acid S, the Ni content and the Co content contained in the battery slag M are reduced from trivalent or tetravalent to divalent to leach a large amount thereof into the sulfuric acid. Thus, it is possible to recover a large amount of the Ni content and the Co content as the second processed residue R2.

[0061] In addition, in the above-described embodiment, the heat treatment step S1 and the crushing step S2 can be appropriately omitted.

[0062] In the above-described embodiment, the washing step of washing the third processed residue R3 with the alkaline aqueous solution to produce the washing product, and the post-washing filtration step of filtering the washing product to be separated into the washing filtrate containing the Li content and the washed residue can be provided. In this case, in the fourth addition step S11, the fourth processed product P4 is produced from the third processed filtrate F3 and the washing filtrate.

[0063] Accordingly, the Li content adhering to a surface or the like of the third processed residue can be washed off by the alkaline aqueous solution without redissolving the hydroxide contained in the third processed residue R3 (hydroxide produced in the third addition step). As a result, this Li content is contained in the washing filtrate. Accordingly, both this Li content and the Li content contained in the third processed filtrate F3 can be recovered.

[0064] As the alkaline aqueous solution, a solution containing a Ca content is used. Specifically, for example, an aqueous calcium hydroxide solution can be used. The alkaline aqueous solution preferably has a pH of 10 or more in order not to dissolve the Mn content and other metal contents contained in the third processed residue R3.

[0065] Furthermore, in the above-described embodiment, the sintering step of sintering the battery slag M including the positive-electrode active material containing Ni and/or Co and the negative-electrode active material containing graphite, and oxidizing the graphite to produce carbon dioxide can be further provided. In this case, the sintering step is performed after the screening step S3, and in the acid leaching step S4, the sulfuric acid is added to the sintered battery slag M.

[0066] Accordingly, in the sintering step, the Ni content and/or the Co content contained in the positive-electrode active material and the graphite contained in the negative-electrode active material in the battery slag M can be brought into contact with each other, and electrons contained in the graphite can be transferred to the Ni content and/or the Co content to produce carbon dioxide. Therefore, the Ni content and the Co content contained in the positive-electrode active material in the battery slag can be reduced to divalent by the sintering and efficiently leached into the sulfuric acid. In addition, the volume of the battery slag can be reduced. Then, in order to add the sulfuric acid to the battery slag M whose volume is reduced, the Ni content and the Co content contained in the positive-electrode active material in the battery slag can be leached out into the sulfuric acid only by the addition of a small amount of the sulfuric acid. Therefore, the Ni content and the Co content contained in the battery slag can be efficiently recovered as the second processed residue R2.

INDUSTRIAL APPLICABILITY

[0067] It is possible to separate and recover the Li content contained in the lithium ion battery from the Na content and the Ca content contained in the additive.

REFERENCE SIGNS LIST

[0068] 1: Heat treatment device [0069] 2: Crushing device [0070] 3: Screening device [0071] 4: Acid leaching device [0072] 5: First addition device [0073] 6: First filtration device [0074] 7: Second addition device [0075] 8: Second filtration device [0076] 9: Third addition device [0077] 10: Third filtration device [0078] 11: Fourth addition device [0079] 12: Fourth filtration device [0080] 13: Heating device [0081] 14: Fifth addition device [0082] 15: Fifth filtration device