METHOD FOR TREATING ALLOY

Abstract

The present invention is a method for treating an alloy, by which a solution that contains nickel and/or cobalt is obtained from an alloy that contains copper, zinc, and nickel and/or cobalt, said method comprising: a leaching process wherein a leachate is obtained by subjecting the alloy to a leaching treatment by means of an acid in the coexistence of a sulfurizing agent; a reduction process wherein the leachate is subjected to a reduction treatment with use of a reducing agent; and an ion exchanging process wherein a solution that contains nickel and/or cobalt is obtained by bringing a solution, which has been obtained in the reduction process, into contact with an amino phosphoric acid-based chelate resin, thereby having zinc adsorbed on the amino phosphoric acid-based chelate resin.

Claims

1. A method for treating an alloy, for obtaining a solution comprising nickel and/or cobalt from an alloy comprising nickel and/or cobalt, copper, and zinc, the method comprising: a leaching step of obtaining a leachate by subjecting the alloy to leaching treatment with acid in a coexistence of a sulfating agent; a reduction step of subjecting the leachate to reduction treatment using a reducing agent; and an ion exchanging step of obtaining a solution including nickel and/or cobalt by bringing the solution obtained in the reduction step into contact with an amino phosphoric acid-based chelate resin and allowing the amino phosphoric acid-based chelate resin to adsorb zinc, wherein in the leaching step, the sulfating agent is added first to the alloy and the acid is then added.

2. The method for treating an alloy according to claim 1, comprising an oxidation neutralization step of adding an oxidizing agent and adding a neutralizing agent to the solution obtained in the reduction step to obtain a solution including nickel and/or cobalt, and zinc, and subjecting the obtained solution to the ion exchanging step.

3. The method for treating an alloy according to claim 1, the method comprising a zinc desorption step of bringing acid into contact with the amino phosphoric acid-based chelate resin after treatment in the ion-exchanging step to detach zinc adsorbed to the amino phosphoric acid-based chelate resin.

4. The method for treating an alloy according to claim 3, wherein the amino phosphoric acid-based chelate resin is used repeatedly by subjecting the amino phosphoric acid-based chelate resin recovered through the zinc desorption step to treatment in the ion exchanging step again.

5. The method for treating an alloy according to claim 1, wherein the alloy is an alloy obtained by melting a waste battery of a lithium ion battery.

6. The method for treating an alloy according to claim 2, the method comprising a zinc desorption step of bringing acid into contact with the amino phosphoric acid-based chelate resin after treatment in the ion-exchanging step to detach zinc adsorbed to the amino phosphoric acid-based chelate resin.

7. The method for treating an alloy according to claim 6 wherein the amino phosphoric acid-based chelate resin is used repeatedly by subjecting the amino phosphoric acid-based chelate resin recovered through the zinc desorption step to treatment in the ion exchanging step again.

8. The method for treating an alloy according to claim 2, wherein the alloy is an alloy obtained by melting a waste battery of a lithium ion battery.

9. The method for treating an alloy according to claim 3, wherein the alloy is an alloy obtained by melting a waste battery of a lithium ion battery.

10. The method for treating an alloy according to claim 4, wherein the alloy is an alloy obtained by melting a waste battery of a lithium ion battery.

11. The method for treating an alloy according to claim 6, wherein the alloy is an alloy obtained by melting a waste battery of a lithium ion battery.

12. The method for treating an alloy according to claim 7, wherein the alloy is an alloy obtained by melting a waste battery of a lithium ion battery.

Description

PREFERRED MODE FOR CARRYING OUT THE INVENTION

[0042] Hereinafter, a specific embodiment of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and can be executed with appropriate modifications within the scope of the object of the present invention. Note here that in this specification, the term “X to Y” (X and Y are arbitrary numerical values) means “X or more and Y or less”.

[0043] The method for treating an alloy of the present embodiment is a method for obtaining a solution including nickel and/or cobalt from an alloy including nickel and/or cobalt, copper, and zinc.

[0044] Examples of the alloy including nickel and/or cobalt, copper, and zinc as a subject to be treated include an alloy obtained by heating and melting, and reducing wastes from raw materials including wastes from deteriorated automobiles or electronic devices, scrap of a lithium ion battery generated with the lifetime of a lithium ion battery, or waste batteries, and the like, of defective products in battery manufacturing processes.

[0045] In the following, a method for treating an alloy is described taking an alloy obtained by melting a waste battery of a lithium ion battery.

[0046] Specifically, a method for treating an alloy includes: a leaching step S1 of subjecting an alloy to leaching treatment with acid in a coexistence of sulfating agent to obtain a leachate; a reduction step S2 of subjecting a leachate to a reduction treatment using a reducing agent; an oxidation neutralization step S3 of adding an oxidizing agent and adding a neutralizing agent to the solution (reduced solution) obtained in the reduction step to obtain a solution including nickel and/or cobalt; and an ion exchanging step S4 of bringing the solution (neutralized solution) obtained in the oxidation neutralization step S3 into contact with an amino phosphoric acid-based chelate resin and allowing the amino phosphoric acid-based chelate resin to adsorb zinc to obtain a solution including nickel and/or cobalt.

[Leaching Step]

[0047] In the leaching step S1, the alloy is subjected to leaching treatment with acid in a coexistence of a sulfating agent to obtain a leachate. The alloy obtained by melting a waste battery of a lithium ion battery contains various impurities that are not subjects to be recovered in addition to copper, nickel, and cobalt. In the present embodiment, by subjecting such an alloy to a leaching treatment in a state in which the acid and the sulfide agent coexist, the copper leached out of the alloy is precipitated as copper sulfide and separated. On the other hand, by subjecting the alloy to leaching treatment with acid, a leachate is obtained by leaching nickel and/or cobalt. Note here that in this leachate, copper that has not been reacted with the sulfating agent, and impurities such as iron, phosphorus, and/or zinc may remain.

[0048] An alloy obtained by melting a waste battery of a lithium ion battery to be treated is not particularly limited in shape, and examples thereof include an alloy obtained by casting the obtained alloy into a plate shape, an alloy drawn linearly and appropriately cut into a rod, a powdery material such as alloy powder obtained by applying an atomization method (hereinafter, this alloy powder is also referred to as “atomized powder” for convenience). However, when the subject to be treated is a powdery material such as atomized powder, leaching treatment can be efficiently carried out. Note here that the atomizing method is a method in which high-pressure gas or water is brought into contact with the molten metal to scatter and quench (solidify) the molten metal to obtain powder.

[0049] When the alloy is made into a powder substance, when the particle diameter of the alloy is about 300 μm or less, the leaching treatment can be carried out more effectively. On the other hand, since too fine particles make the cost high, and may cause dust generation or ignition, the particle diameter of the alloy is preferably about 10 μm or more.

[0050] In the leaching treatment, the alloy to be treated is preferably pre-washed with a dilute acid in advance. Thus, the surface of the alloy can be subjected to active treatment, and the leaching reaction can be promoted.

[0051] As the acid, hydrochloric acid, sulfuric acid, nitric acid, or the like, can be used alone or in combination. Furthermore, chloride may be contained in sulfuric acid and used as an acid. In order to achieve a so-called “battery-to-battery” which is an ideal circulation method for recycling waste LIB and reusing it as a LIB raw material, it is preferable to use an acid including sulfuric acid. When sulfuric acid is used as the acid, the leachate can be obtained in the form of sulfate, which is easily used as the positive electrode material of the lithium ion battery.

[0052] The amount of acid used is 1 equivalent or more, preferably, 1.2 equivalents or more, more preferably 1.2 equivalents or more and 11 equivalents or less, relative to the total amount of nickel and/or cobalt included in the alloy. Thus, the reaction rate can be increased by increasing the acid concentration.

[0053] The acid and the alloy may be supplied to a device in which a plurality of stages of mixing portions, such as thickeners, are connected, and the acid and the alloy may be brought into contact with each other in a stepwise manner in a countercurrent. For example, an alloy may be supplied to the mixing portion at the top of the device, an acid may be supplied to the mixing portion at the bottom of the device, and the acid and the alloy may be brought into contact with each other in a stepwise manner in a countercurrent.

[0054] Sodium hydrosulfide or elemental sulfur can be used as the sulfating agent to be added together with the acid. When the elemental sulfur is used, it is preferable that the elemental sulfur is appropriately pulverized so as to facilitate the reaction.

[0055] The amount of the sulfating agent is preferably 1 equivalent or more with respect to the amount of copper included in the alloy.

[0056] The acid and the sulfating agent may be added to the alloy at the same time, but it is preferable that the sulfating agent is added first and the acid is then added. When the acid and the sulfating agent are added to the alloy at the same time, the reaction may proceed rapidly and bumping may occur. By adding the sulfating agent first, and then bringing the acid into contact therewith, a rapid reaction can be suppressed. When the sulfating agent is added first, and then the acid is then added, for example, an alloy and the sulfating agent are charged into a solvent such as water, and then the acid is added. Furthermore, in order to proceed a homogeneous reaction, the leachate may be bubbled with air or the like.

[0057] It is preferable to carry out a preliminary test in advance to determine an appropriate range for temperature, time, and the concentration of slurry obtained by adding an acid and a sulfating agent to the alloy, in the leaching step S1.

[0058] In particular, in the leaching step S1, it is preferable to monitor and control the range of the oxidation-reduction potential (ORP) and pH while the oxidation-reduction potential (ORP) and pH of the leachate are measured. Specifically, the oxidation-reduction potential (ORP) is preferably controlled to 240 mV or more and 280 mV or less on the basis of the silver/silver chloride electrode, and the pH is preferably controlled to 0.8 or more and 1.6 or less. Within such a range, leaching is promoted and re-dissolution due to excessive oxidation of the precipitated copper sulfide can be suppressed.

[0059] The end point of the leaching reaction can be determined by measuring the oxidation-reduction potential (ORP) of the leachate, and determining the end portion of leaching of nickel and/or cobalt.

[0060] Note here that in the leaching treatment, a divalent copper ion may be added. Thus, the divalent copper ion acts as a catalyst, and the leaching reaction can be promoted.

[Reduction Step]

[0061] In the reduction step S2, the leachate obtained in the leaching step S1 is subjected to reduction treatment using a reducing agent. Herein, in the treatment in the leaching step S1 described above, copper constituting the alloy, together with nickel and/or cobalt, is leached by acid and dissolved in the solution, and a part of the copper remains in the solution without reacting with the sulfating agent. Then, in the reduction step S2, a small amount of copper remaining in the leachate is reduced to produce a precipitate including copper, and the produced precipitate is separated by solid-liquid separation to obtain a solution (reduced solution) including nickel and/or cobalt.

[0062] As the reducing agent, for example, a less noble metal than copper can be used. Among them, preferably, metal including nickel and/or cobalt is used, and copper is reduced by bringing the leachate into contact with the metal. The treatment method of the alloy treatment method according to the present embodiment obtains a solution including nickel and/or cobalt, and is industrially advantageous because by using a metal including nickel and/or cobalt to be recovered as a reducing agent, there is no need to recover the reducing agent separately in a subsequent step.

[0063] Note here that as the reducing agent, in addition to the metal mentioned above, sulfide can be used. Sulfide may be solid, liquid or gas (gaseous form). Sulfide may also be a mixture of the powdery substance of the alloy to be treated in the leaching step S1 described above and sulfur. In addition, it is preferable to use atomized powder obtained by quenching and pulverizing the molten metal of the alloy into powder.

[0064] The method for reducing the leachate is not particularly limited, and when a solid or liquid reducing agent is used, the reducing agent may be directly added to the leachate, and when the reducing agent is gas (gaseous form), the reducing agent may be added by bubbling to the leachate.

[0065] It is preferable that the addition amount of the reducing agent and the reaction temperature be tested in advance to select the optimum range. Furthermore, the reduction treatment is preferably controlled by monitoring the oxidation-reduction potential (ORP) and pH and adding a reducing agent or the like as appropriate to control them, and it is preferable to select the optimum range by carrying out a test in advance.

[Oxidation Neutralization Step]

[0066] In the oxidation neutralization step S3, oxidation neutralization treatment is carried out by adding an oxidizing agent and adding the neutralizing agent to the solution (reduced solution) obtained in the reduction step S2 to obtain a solution (neutralized solution) including nickel and/or cobalt, and zinc. Specifically, in the oxidation-neutralization step S3, an oxidizing agent is added to the reduced solution to cause an oxidation reaction, and when a neutralizing agent is added to control the pH of the solution to a predetermined range, at least a precipitate of iron and/or phosphorus included in the reduced solution is produced. Although it is not essential to provide the oxidation neutralization step S3 in the present invention, at least iron and/or phosphorus can be separated as a precipitate through the oxidation neutralization step S3 to obtain a purified solution (neutralized solution) including nickel and/or cobalt and zinc.

[0067] The oxidizing agent is not particularly limited, and conventionally known oxidizing agents such as hydrogen peroxide and hypochlorous acid can be used.

[0068] Addition of the oxidizing agent is preferably controlled within a predetermined range by monitoring the oxidation-reduction potential (ORP) of the solution. Specifically, an oxidizing agent is added to the solution to control the ORP (using silver/silver chloride as a reference electrode) in a range of, for example, 380 mV to 430 mV.

[0069] Furthermore, an oxidizing agent is added so as to cause an oxidation reaction, and a neutralizing agent is added so as to control the pH of the solution, preferably, in a range of 3.8 or more and 4.5 or less. When neutralization treatment is carried out by controlling the pH in such a range, impurities such as at least iron and/or phosphorus can be effectively precipitated.

[0070] The neutralizing agent is not particularly limited, but conventionally known alkalis such as sodium hydroxide and potassium hydroxide can be used.

[0071] Herein, in the oxidation neutralization treatment, the oxidizing agent may be added to the reduced solution after addition of the neutralizing agent, but it is preferable that the oxidizing agent and the neutralizing agent are added to the reduced solution at the same time or the neutralizing agent is added after addition of the oxidizing agent, and it is more preferable that the neutralizing agent is added to the reduced solution after addition of the oxidizing agent. For example, when an oxidizing agent is added to the reduced solution having a high pH by the addition of the neutralizing agent, in a case where iron is included in impurities, the iron is not sufficiently oxidized, Fe(OH).sub.3 precipitate (iron sediment) is not sufficiently generated, and separation of the impurities may become insufficient.

[0072] [Ion Exchanging Step]

[0073] In the ion exchanging step S4, the obtained solution is brought into contact with an amino phosphoric acid-based chelate resin to allow the amino phosphoric acid-based chelate resin to adsorb zinc so as to obtain a solution including nickel and/or cobalt. Specifically, the obtained solution is used as a target solution for ion exchange treatment, and zinc included in the solution is separated and removed by a method of ion exchange treatment using an amino phosphoric acid-based chelate resin to obtain a solution containing nickel and/or cobalt. The ion exchanging step S4 may be a liquid passing treatment using a column or may be a batch treatment using a beaker or the like.

[0074] The amino phosphoric acid-based chelate resin is a chelate resin having an amino phosphoric acid as a functional group. Examples of the amino phosphoric acid-based chelate resin include “Duolite C747” (trade name) manufactured by Sumitomo Chemical Co., Ltd.

[0075] Note here that after the ion exchanging step S4, a zinc desorption step of bringing the amino phosphoric acid-based chelate resin after the treatment in the ion exchanging step S4 into contact with about 1 N acid, detaching zinc adsorbed to the amino phosphoric acid-based chelate resin may be provided. Examples of acid to be used in the treatment in the zinc desorption step include conventionally known acids such as hydrochloric acid and sulfuric acid. Furthermore, the amino phosphoric acid-based chelate resin recovered through the zinc desorption step is subjected to the treatment in the ion-exchanging step again, the amino phosphoric acid-based chelate resin can be used repeatedly.

EXAMPLES

[0076] The present invention will be described in further detail below with reference to Examples, but the present invention is not limited to the Examples below at all.

Example 1

[Leaching Step]

[0077] A waste lithium ion battery (waste LIB) was subjected to pyrometallurgical treatment of carrying out reduction by heating and melting, and an alloy obtained by reducing and melting was poured into a small crucible having a hole in the bottom surface, and the molten metal flowing out of the hole was sprayed with high-pressure gas or water, and the molten metal was scattered and solidified to obtain a powdery material (atomized powder) having a particle diameter of 300 μm or less. The resultant powdery material was used as an alloy to be treated. The composition is shown in Table 1.

TABLE-US-00001 TABLE 1 Ni Co Cu Fe P Alloy grade 40 20 38 1.4 0.5 (mass %)

[0078] The powdery material having the composition shown in Table 1 was leached with sulfuric acid and sulfur at a slurry concentration of 200 g/L. The temperature was 70° C. and the leaching time was 6 hours. After leaching, solid-liquid separation was carried out by filtration, and the filtrate (leachate) was analyzed by an ICP analyzer, and the concentration of each element was obtained (in Table 2, referred to as “leachate”).

[Reduction Step]

[0079] Next, a nickel powder (reducing agent) having a particle diameter of 1 μm to 300 μm was added to the resulting leachate, and the leachate was subjected to reduction treatment using a reducing agent, filtered, and solid-liquid separated, and the resulting filtrate (reduced solution) was analyzed by an ICP analyzer to determine the concentrations of the elemental components (In Table 2, referred to as “leachate”).

[Oxidation Neutralization Step]

[0080] Next, while the obtained reduced solution was maintained at liquid temperature of 60° C. to 70° C., a hydrogen peroxide solution (oxidizing agent) having a concentration of 30% was added. After the hydrogen peroxide solution (oxidizing agent) was added, a sodium hydroxide solution (neutralizing agent) was added. Thus, the reduced solution was subjected to an oxidation neutralization reaction. The oxidation-reduction potential (ORP) at this time was in the range of 380 mV to 430 mV with a silver-silver chloride electrode used as the reference electrode, and the pH was in the range of 3.8 or more and 4.5 or less. After the reaction, solid-liquid separation by filtration, a filtrate (neutralized solution) was analyzed by an ICP analyzer, the concentration of each element component was obtained (in Table 2, referred to as “neutralized solution”).

TABLE-US-00002 TABLE 2 (g/L) Ni Co Cu Fe P Leachate 76 38 5 2.8 1 Reduced 80 38 0.001 2.8 1 solution Neutralized 80 38 0.001 0.001 0.001 solution

[0081] From Table 1, 38 mass % copper was included in an alloy before the leaching step, but from Table 2, the concentration of copper in the leachate after the leaching step was 5 g/L, and was relatively lower as compared with the concentration of nickel or cobalt. This is considered because most of copper in the alloy (powder) was precipitated as copper sulfide and separated through the leaching step.

[0082] On the other hand, from Table 2, it is found that while the concentration of copper in the leachate was 5 g/L, the concentration of copper in the reduced solution was lower as 0.001 g/L. This is considered because a small amount of copper remaining in the leachate was reduced through the reduction step and separated as a sediment.

[0083] Furthermore, from Table 2, it is found that while the concentration of iron in the reduced solution is 2.8 g/L and the concentration of phosphorus in the reduced solution is 1 g/L, the concentration of iron in the neutralized solution is 0.001 g/L and the concentration of phosphorus in the reduced solution is low as 0.001 g/L. This is considered because iron or phosphorus was separated as a sediment through the oxidation neutralization step.

Example 2

[0084] The other waste lithium ion battery (waste LIB) being different from that of the above Example 1 was prepared, and similarly, a neutralized solution (starting solution) was obtained through a leaching step, a reduction step, and an oxidation neutralization step. This neutralized solution (starting solution) was analyzed by an ICP analyzer to obtain the concentration (g/L). The concentration (g/L) of each element component was shown in Tables 3 and 5 (in Tables, referred to as “neutralized solution (starting solution)”).

[Ion Exchanging Step]

[0085] An amino phosphoric acid-based chelate resin (Duolite C747): 20 ml, and a neutralized solution 100 ml obtained in the oxidation neutralization step were placed in a glass beaker and stirred with a stirrer for 30 minutes to bring the neutralized solution into contact with the amino phosphoric acid-based chelate resin to perform ion exchange treatment. After stirring, the amino phosphoric acid-based chelate resin and a solution (final solution) were separated, and the solution (final solution) was analyzed by the ICP analyzer to determine the concentration (g/L) of each element component. The concentrations of elements are shown in Table 3 (referred to as “final solution” in the table).

TABLE-US-00003 TABLE 3 Ni Co Mn Zn Example2 (g/L) (g/L) (g/L) (g/L) Neutralized solution 29.0 29.6 0.14 0.05 (Starting solution) Final solution 25.7 24.6 0.070 0.004

[0086] On the other hand, the amino phosphoric acid-based chelate resin after the ion exchange treatment was brought into contact with white fume sulfuric acid, and each element component adsorbed to the amino phosphoric acid-based chelate resin was analyzed by the ICP analyzer to obtain an analytical value, and the adsorption rate (%) of the chelate resin was obtained from the analytical value. Table 4 shows the adsorption rate (%) of each element component.

TABLE-US-00004 TABLE 4 Ni Co Mn Zn Example 2 (%) (%) (%) (%) Adsorption 11.5 16.9 49.8 92.6 rate

Example 3-5

[0087] In Example 2, an amino phosphoric acid-based chelate resin different from Duolite C747 was used, and similarly, the neutralized solution obtained in the oxidation neutralization step was subjected to ion exchange treatment, and similarly, the concentration (g/L) of each element component in the final solution and the adsorption rate (%) of chelate resin were obtained. The concentration (g/L) of each element component is shown in Table 5, and the adsorption rates (%) of chelate resins are shown in Table 6.

TABLE-US-00005 TABLE 5 Concentration of each element component Ni Co Mn Zn (g/L) (g/L) (g/L) (g/L) Neutralized solution (Starting solution) 29.0 29.6 0.14 0.052 Final Example R S950 26.1 26.1 0.10 0.036 solution 3 manufactured by Purolite Example Sumichelate 25.6 24.7 0.074 0.007 4 MC950 manufactured by Sumika Chemtex Company, Limited Example UR-3300 27.8 29.1 0.12 0.035 5 manufactured by UNITIKA LTD.

TABLE-US-00006 TABLE 6 Adsorption rate Ni Co Mn Zn (%) (%) (%) (%) Final Example3 R S950 manufactured 10.1 11.9 27.0 30.2 solution by Purolite Example4 Sumichelate MC950 11.7 16.7 46.6 87.3 manufactured by Sumika Chemtex Company, Limited Example35 UR-3300 4.11 1.58 16.4 33.6 manufactured by UNITIKA LTD.

[0088] As is apparent from Tables 3 to 6, it is shown that in Examples 2 to 5 in which the neutralized solution was brought into contact with the amino phosphoric acid-based chelate resin, zinc is adsorbed and zinc is separated to obtain nickel and/or cobalt.

[0089] Among them, in Example 2 in which Duolite C747 was used as the amino phosphoric acid-based chelate resin, it is shown that the adsorption rate of zinc was highest, and from an alloy including copper and zinc, zinc is separated more efficiently to obtain nickel and/or cobalt.

Comparative Example

[0090] In Example 2, a chelate resin different from the amino phosphoric acid-based chelate resin (Diaion CR 11 type which is an iminodiacetic acid-based chelate resin manufactured by Mitsubishi Chemical Corporation) was used to similarly perform ion exchange treatment on the neutralized solution obtained in the oxidation neutralization step (Comparative Example). However, with the iminodiacetic acid-based chelate resin, the adsorption of zinc was not observed (adsorption rate: 0.0%), and the objective of the present invention to obtain nickel and/or cobalt by separating zinc was not able to be achieved.