JPH1046266A - How to recover cobalt from waste batteries - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for recovering cobalt from waste secondary battery, which can efficiently recover rare metal cobalt from waste battery of secondary battery using as little acid as possible. . SOLUTION: A roasting step of roasting a waste battery of a secondary battery containing cobalt in an electrode material at a temperature of 600 ° C or higher, a cutting step of cutting the roasted battery obtained in the roasting step,
A sieving step of sieving the cut pieces of the roasted battery obtained in this cutting step into metal scrap and roasted ash, and using a magnet from the roasted ash obtained in the sieving step to remove cobalt from the roasted ash. A magnetic separation step of magnetically separating the inclusions, an acid dissolving step of dissolving the cobalt-containing substance selected in the magnetic separation step in an acid, and a recovery step of recovering cobalt from the acid dissolved product obtained in the acid dissolving step. This is a method for recovering cobalt from waste secondary batteries.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently removing the rare metal cobalt contained in the electrode material from battery waste such as defective products generated in the secondary battery manufacturing process and recovered products of used secondary batteries. The present invention relates to a method for recovering cobalt from waste secondary batteries that can be recovered.

[0002]

2. Description of the Related Art For example, lithium ion secondary batteries use cobalt lithium oxide (LiCoO ₂ ) as a positive electrode material, and nickel hydride batteries use nickel hydride as an active material of the positive electrode material. Cobalt oxide is added for the purpose of improving the capacity utilization factor, and cobalt nitrate is added to the cathode material (nickel) of the NiCd battery for the purpose of improving the corrosion resistance and increasing the capacity.

[0003] In the case of a lithium ion secondary battery, for example, such a positive electrode material is prepared by mixing lithium carbonate and cobalt oxide, and calcining the mixture to form cobalt lithium oxide.
Next, the lithium cobaltate is mixed with a conductive agent such as acetylene black or carbon, and a binder such as a fluororesin or a fluororubber, and the resulting mixture is kneaded in a slurry with an organic solvent. (Referred to simply as "aluminum foil"), etc., uniformly applied on a metal foil, dried to remove the solvent, 2 to 10% by weight of conductive agent and 2 to 10% by weight of binder are applied to the metal foil, This is formed by cutting this into a predetermined shape.

[0004] By the way, the demand for such a secondary battery is rapidly increasing with the spread of portable electric equipment such as a notebook personal computer, a portable telephone, a portable telephone (PHS), an electric shaver, a headphone stereo, and a VTR. As the production volume increases, the amount of battery waste such as defective products generated during the manufacture of this secondary battery and the collection of used secondary batteries increases dramatically, and the disposal of these battery wastes becomes a problem. Is coming.

[0005] On the other hand, although cobalt is scarce in resources and most of it depends on foreign countries in Japan, its uses are as electrode materials for secondary batteries, pigments, ceramics, ferrites, catalysts, and cemented carbides. Etc., ranging from daily necessities to high-tech products. In particular, about 7 g of cobalt oxide per lithium ion secondary battery
Is also used. For this reason, cobalt is inherently expensive and its demand is increasing, and it is becoming more and more expensive.

For this reason, conventionally, for example, wastes of cemented carbides and catalysts are subjected to an acid dissolution treatment, and an extract containing alkyl phosphoric acid is extracted from the resulting acid solution containing cobalt and nickel. Selectively extract ions,
Furthermore, there has been proposed a method of recovering cobalt with high purity from a solution containing cobalt and nickel by contacting the obtained extract with an aqueous oxalic acid solution to precipitate and recover cobalt oxalate (Japanese Patent Application Publication No. Hei 5 (1999)). -14013).

[0007]

Therefore, the above-mentioned battery waste is also crushed and dissolved with a mineral acid such as hydrochloric acid or nitric acid, and the conductive material such as insoluble acetylene black or carbon, fluororesin, fluororubber or the like is used. Separation and removal of binders etc., recover acid solution containing cobalt and other metals such as lithium and aluminum, and selectively recover cobalt from this acid solution using an extractant containing alkyl phosphoric acid. That is being considered.

However, in this method, not only the metal compounds such as cobalt and lithium in the battery waste are dissolved in the acid solution but also the aluminum and the like of the metal foil are dissolved. As the amount increases, the amount of acid required for this acid dissolution treatment, for example, hydrochloric acid or nitric acid, increases significantly, and a large amount of acid waste liquid is generated after extracting cobalt ions from the acid solution with an extractant. In addition, a large amount of alkali such as sodium hydroxide is required to treat this large amount of acid waste solution, which in turn causes a great deal of problems in waste solution treatment.If hydrochloric acid is used as the acid, a large amount of chlorine gas is generated during acid dissolution treatment In addition, when nitric acid is used, a large amount of nitrous acid gas is generated during the acid dissolving treatment, and there is also a problem that the treatment of such acidic exhaust gas requires a large cost.

First, metal foil such as aluminum foil and a part of lithium compound in battery waste are dissolved and removed in alkali such as sodium hydroxide, and then cobalt compound in remaining cathode material is removed. Other metal compounds, conductive agents, binders, etc. are subjected to acid dissolution treatment with a mineral acid such as hydrochloric acid to separate the soluble positive electrode material from the conductive agents and binders and contain metals such as cobalt and lithium. A method of obtaining an acid solution and selectively recovering cobalt with an extractant containing alkyl phosphoric acid is also conceivable.

However, in this method, apart from the acid leaching treatment, an alkali pretreatment for separating and removing the metal foil with an alkali is required, which complicates the process. A large amount of the used alkaline waste liquid or acid waste liquid is generated, and in the same manner as described above, a large problem occurs in the waste liquid treatment, and there remains an acidic exhaust gas problem during the acid leaching treatment.

Further, Japanese Patent Application Laid-Open No. Hei 3-10032 discloses that
A method for selectively and directly extracting cobalt from cobalt and nickel oxide by using an organic solution containing an alkyl phosphoric acid in the presence of water is disclosed.

However, also in this method, a metal compound such as a cobalt compound is coated with a conductive agent or a binder in the positive electrode material, and the presence of the conductive agent or the binder hinders the formation of the alkyl phosphate. The extractant of the organic solution-water system containing the compound cannot efficiently contact the cobalt compound, and the extraction efficiency of this extractant is as low as about 30 to 40% by weight even at high efficiency, which is not a value that can be practically used industrially.

The inventors of the present invention have conducted intensive studies on how to separate and recover the rare metal cobalt from battery waste. As a result, the battery waste was roasted at 600 ° C. or higher, and then cut. The roasted ash obtained by sieving is subjected to magnetic separation of a cobalt-containing material mainly composed of metal cobalt and cobalt oxide using a magnet, and the obtained cobalt-containing material is subjected to an acid dissolution treatment and a solvent extraction treatment. As a result, it has been found that cobalt in battery waste can be efficiently recovered without using a large amount of acid, and the present invention has been completed.

Accordingly, an object of the present invention is to provide a method for recovering cobalt from waste secondary batteries, which can efficiently recover rare metal cobalt from waste batteries of secondary batteries by using as little acid as possible. To provide.

[0015]

That is, according to the present invention, a waste battery of a secondary battery containing cobalt in an electrode material is heated to 600 ° C.
A roasting step of roasting at the above temperature, a cutting step of cutting the roasted battery obtained in this roasting step, and a metal scrap by sieving the cut piece of the roasted battery obtained in this cutting step. A sieving step of separating into roasted ash containing the cobalt-containing material, and a magnetic separation step of magnetically separating the cobalt-containing material from the roasted ash obtained in the sieving step using a magnet,
A method for recovering cobalt from waste secondary batteries, comprising: an acid dissolving step of dissolving the cobalt-containing substance selected in the magnetic separation step in an acid; and a collecting step of recovering cobalt from the acid dissolved substance obtained in the acid dissolving step. It is.

Further, the present invention provides a roasting step of roasting a waste battery of a secondary battery containing cobalt in an electrode material at a temperature of 600 ° C. or more, and cutting the roasted battery obtained in the roasting step. Cutting step, a magnetic separation step of magnetically separating the cut piece of the roasted battery obtained in the cutting step into a magnetic substance and a non-magnetic substance by a magnet, and sieving the magnetic substance obtained in the magnetic separation step to obtain a magnetic material. A sieving step of separating into metal scrap and a cobalt-containing substance, an acid dissolving step of dissolving the cobalt-containing substance obtained in the sieving step in an acid, and cobalt from the acid dissolved substance obtained in the acid dissolving step. And a collecting step for collecting cobalt from waste secondary battery.

In the method of the present invention, waste secondary batteries to be subjected to cobalt recovery are defective products generated during the manufacture of secondary batteries, recovered products of used secondary batteries, and the like, and the electrode material contains cobalt. It is a thing. As the secondary battery containing cobalt in the electrode material, typically, for example, a lithium ion secondary battery containing a cobalt compound such as cobalt oxide or cobalt nitrate in its positive electrode material, a nickel hydrogen battery, a nickel cadmium battery, etc. Can be mentioned.

In the method of the present invention, firstly, the waste battery of the secondary battery containing cobalt in the electrode material as described above is kept at 600 ° C.
Above, preferably at a temperature of 700 to 900 ° C, usually 1 to 3
Roast for about an hour. The roasting treatment in the roasting step of the battery waste is preferably performed in a closed vessel or in a reducing atmosphere, and efficiently separates the cobalt-containing material mainly composed of metal cobalt and cobalt oxide in the magnetic separation step. Therefore, at least a part of the cobalt compound in the electrode material needs to be reduced to metal cobalt. Here, when the roasting temperature is lower than 600 ° C., the amount of metallic cobalt in the cobalt-containing material in the obtained roasted ash decreases,
It becomes difficult to efficiently magnetically separate the cobalt-containing material in the magnetic separation step. Further, even if the roasting temperature exceeds 900 ° C., there is no particular problem in the separation of the cobalt-containing material in the magnetic separation step, but the energy cost in the roasting step increases, which is not preferable for industrial implementation. .

In the roasting step, for example, cobalt oxide (eg, Co ₂ O ₃ ) in the positive electrode material of the battery waste is reduced using aluminum (Al), carbon (C), etc. in the battery waste as a reducing agent. It is conceivable that cobalt oxide (Co ₃ O ₄ ), which is partially reduced to be completely converted to magnetic cobalt (Co) as a magnetic substance and partially reduced to be produced, exists together with the metal cobalt.

The roasted battery obtained in the above-mentioned roasting step is then cut by a cutter into a cut product, and the cut product of the roasted battery is formed of a metal such as iron, aluminum, stainless steel or the like. Relatively large scrap metal scrap derived from the outer container of the battery or the current collector formed of metal foil such as aluminum foil or copper foil, and metal such as a cobalt compound applied to the current collector Compounds, conductive materials such as acetylene black and carbon, and positive electrode materials and negative electrode materials such as binders such as fluororesins and fluororubbers, and metallic cobalt and cobalt derived from organic substances such as separators formed of polyethylene porous films and the like. There is a relatively small powdered or granular roasted ash made of oxide or other metal, its oxide, carbon or the like.

The cut piece of the roasted battery obtained in the above cutting step is sieved into a relatively large piece of metal scrap and a relatively small powdery or granular roasted ash in the sieving step. It is separated and separated, and then the cobalt-containing material of the magnetic substance is separated in the magnetic separation step, or
First, it is separated into a magnetic substance and a non-magnetic substance by a magnet in a magnetic separation step, and then the magnetic substance is sieved in a sieving step to be separated into a magnetic metal scrap and a cobalt-containing substance. In order to reduce the amount of metal scrap and the roasted ash more completely, it is preferable that the former is sieved and then the magnetic separation is performed.

In the sieving step, preferably, a vibrating sieve is used to remove as much as possible the roasted ash adhering to the metal scrap, and the collected metal scrap, such as iron, stainless steel, aluminum and copper, is recycled. To be used effectively. Further, in the magnetic separation step, although not particularly limited, for example, using a drum type wet separator, a belt type wet separator, and various types of dry separators and the like, using a magnetic substance and a non-magnetic substance The magnetic separation is performed using the difference in the adhesion time between the magnetic field and the magnetic field.

Here, the roasted ash obtained in the sieving step is, if necessary, pulverized by a pulverizer such as a ball mill before being transferred to the magnetic separation step. 2 mm or less, preferably 1.65
1 mm (12 mesh) or less, more preferably 1.16
It is preferable to grind to 8 mm (16 mesh) or less. By crushing the roasted ash to an average particle size of 2 mm or less, a powder containing a relatively high concentration of metal cobalt and cobalt oxide and a powder containing a metal other than cobalt and its oxide at a relatively high concentration In the magnetic separation step, a cobalt-containing material containing relatively high concentrations of metallic cobalt and cobalt oxide is obtained.

The cobalt-containing material obtained from the sieving step through the magnetic separation step, or from the magnetic separation step through the sieving step, is applied to the roasted ash before magnetic separation generated by cutting the roasted battery. If the weight is reduced even a little, the amount of acid used in the subsequent acid dissolution treatment will be reduced accordingly, and the effect of reducing the amount of acid used in the acid dissolution step will be obtained. The amount of the acid used in the acid dissolving step is preferably reduced as much as possible, and on the industrial basis, the weight ratio is preferably 0.6 or less, more preferably the roasted ash before magnetic separation. Is preferably 0.5 or less.

The cobalt-containing material obtained in the magnetic separation step is mainly composed of metallic cobalt and cobalt oxide. In addition to these, for example, metals such as copper and aluminum sintered with metallic cobalt and their metals. Contains a significant proportion of oxides. The total content of metal cobalt and cobalt oxide in the cobalt-containing material (hereinafter simply referred to as “cobalt content”) is usually 20% by weight.
It is preferably at least 40% by weight. The higher the cobalt content, the smaller the amount of acid required per unit amount of cobalt, and the smaller the amount of acid used in the acid dissolving step.

In the present invention, the cobalt-containing substance obtained in the magnetic separation step is then dissolved using a suitable acid such as hydrochloric acid, sulfuric acid, nitric acid, etc., to obtain an acid-dissolved substance (acid dissolving step). Examples of the acid used in the acid dissolving step include mineral acids such as hydrochloric acid and sulfuric acid, and the amount of the acid is usually in the range of 1 to 3 mol per mol of the cobalt-containing substance.

The acid dissolved product obtained in the acid dissolving step is then transferred to a recovery step for recovering cobalt. The recovery step may be any step capable of selectively recovering cobalt from the acid solution. For example, the metal compound other than the cobalt compound is separated and removed as much as possible by adjusting the pH, and then adjusted to pH 10. To precipitate cobalt hydroxide and reduce the cobalt hydroxide in a reducing atmosphere to recover it as metallic cobalt, or to selectively liquid-liquid extract a cobalt compound in an organic phase with an organic solvent containing alkyl phosphoric acid. (Japanese Patent Publication No. 56-11371,
No. 14013) and organic solvents containing alkyl phosphoric acid.
A method in which a cobalt compound is selectively solid-liquid extracted with heating and stirring using a water-hydrogen peroxide (water-soluble reducing agent) emulsion extractant (Japanese Patent Application No. 7-268881), preferably a solvent This is a solvent extraction method for recovering cobalt by extraction.

The alkyl phosphoric acid used to extract the cobalt compound by this solvent extraction method includes, for example, 2
Monoalkyl esters of alkyl phosphonic acids such as -ethylhexyl phosphonic acid mono-2-ethylhexyl ester (M2EHPA) and dialkyl phosphoric acids such as bis-2-ethylhexyl phosphate (D2EHPA) and bis-2-dodecyl phosphate; Having 6 or more carbon atoms.

The remaining roasted ash obtained by separating the cobalt-containing material by the magnetic separation according to the present invention contains abundant metals such as copper. Therefore, if necessary, these metals may be subjected to a method such as electrolytic refining, if necessary. May be collected.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the method for recovering cobalt from waste secondary batteries according to the present invention will be described below with reference to the flowcharts shown in the accompanying drawings.

First, using a device such as an electric furnace or a gas furnace, the battery waste is kept at a temperature of 600 ° C. or more,
Bake at 0 ° C for 1-3 hours. By this roasting treatment, a part of the cobalt compound in the battery waste is reduced to metallic cobalt, and at that time, the other cobalt compound is present as a cobalt oxide attached or adsorbed to the metallic cobalt. Conceivable.

Next, the roasted battery obtained in the roasting step is cooled to room temperature by standing cooling or forced cooling, and cut into a size of, for example, 3 to 10 mm by a cutting machine such as a shredder. And the cut piece of the roasted battery obtained in the cutting step is
Next, it is sieved into metal scrap and roasted ash by using a vibrating sieve or the like, preferably under a condition where 20 mesh can be sieved.

The roasted ash obtained in this sieving step is obtained by using an electromagnet or the like to leave a cobalt-containing material mainly composed of metallic cobalt and cobalt oxide and a residual metal mainly composed of other metals and their oxides. Magnetic separation into ash. Here, the ratio of magnetic separation as a cobalt-containing material is preferably not more than 0.6, more preferably not more than 0.5, by weight, relative to the roasted ash before magnetic separation. Are concentrated to a concentration of 1.6 to 2 times or more.

The cobalt-containing material selected in the magnetic separation step is as follows:
Next, the compound is dissolved in a mineral acid such as hydrochloric acid or sulfuric acid (acid dissolving step), and then the cobalt compound in the acid solution is selectively liquid-liquid extracted into the organic phase with an organic solvent containing alkylphosphoric acid and recovered.

In the present invention, the waste rechargeable battery is roasted and then cut, and then the metal scrap and the roasted ash are sieved. The obtained roasted ash is separated by a magnet in a magnetic separation step. Since the cobalt-containing material containing metal cobalt and cobalt oxide in high concentration is used, and then the cobalt-containing material is subjected to acid dissolution treatment and solvent extraction treatment to recover cobalt, the amount of acid used in the acid dissolution treatment is required. Can be reduced as much as possible, and the recovery efficiency of cobalt can be improved.

[0036]

EXAMPLES The method of the present invention will be specifically described below based on examples and comparative examples.

Example 1 One waste cylindrical lithium ion secondary battery having an outer dimension of 18 mmφ × 65 mm and a weight of 35.93 g was used, placed in the center of an annular electric furnace, and roasted at 800 ° C. for 2 hours. Baked.

The roasted battery obtained by the roasting process was cut into a size of about 10 mm using a cutting machine, and the obtained cut product was sieved using a 16-mesh vibrating sieve. . By this sieving, 14.38 g of metal scrap on a sieve mainly composed of cut pieces such as iron pieces derived from a battery container, copper foil pieces derived from a negative electrode material, and aluminum foil pieces derived from a positive electrode material, and roasting ash 16 .81 g.

Using 16.81 g of the roasted ash obtained by the above sieving treatment, using an electromagnet, 14.57 g of a cobalt-containing substance adsorbed by the electromagnet and 2.24 g of other residual ash not adsorbed by the electromagnet were obtained. And the content of cobalt was recovered. The weight ratio of the cobalt-containing material recovered by the magnetic separation process with respect to the roasted ash before the magnetic separation was 0.87, and the metal cobalt and the cobalt oxide in the roasted ash were concentrated 1.15 times.

Next, 14.57 g of the cobalt-containing material thus obtained was mixed with 10% by weight hydrochloric acid and 10% by weight.
The mixture was dissolved in 186 ml of a mixed acid of 2% by weight of nitric acid of 2% by weight and filtered to separate and remove 4.61 g of an insoluble substance to obtain an acid dissolved substance.

The obtained acid solution is adjusted to pH 6 using a 10% by weight aqueous solution of sodium hydroxide, and iron, aluminum and copper ions contaminated as impurities are precipitated as hydroxides and removed by filtration. After that, the obtained filtrate was adjusted to pH 10 to precipitate cobalt hydroxide, and the precipitate of cobalt hydroxide was collected by filtration and dried to obtain 10.78 g of cobalt hydroxide. 10.78 g of this cobalt hydroxide was heated in a hydrogen stream at 500 ° C. for 1 hour, and reduced to obtain 6.84 g of metallic cobalt. The purity of the obtained metallic cobalt was 99.3%, and the cobalt recovery rate with respect to all the cobalt contained in the battery waste was 87.8%.
Met.

Comparative Example 1 16.81 g of the roasted ash obtained in Example 1 was used as it was in Example 1 without magnetic separation in a magnetic separation step (hydrochloric acid having a concentration of 10% by weight and hydrochloric acid having a concentration of 10% by weight). When dissolved in a 2: 1 weight ratio of nitric acid, 221 ml of mixed acid was obtained.
And 4.90 g of insoluble matter was separated and recovered by filtration. The obtained acid solution was treated in the same manner as in Example 1 to recover metallic cobalt. The purity of the obtained metallic cobalt was 85.9%, and the cobalt recovery rate with respect to all the cobalt contained in the battery waste was 87.1%.
%Met.

[0043]

According to the present invention, the rare metal cobalt can be efficiently recovered from the waste battery of the secondary battery by using as little acid as possible, which is of high industrial value.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a method for recovering cobalt from waste secondary batteries according to a preferred embodiment of the present invention.

Continued on the front page (72) Inventor Shunpei Shimizu 12-1, Ekimae Honcho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture, inside Tama Chemical Industry Co., Ltd.

Claims (8)

[Claims] 1. A roasting step of roasting a waste battery of a secondary battery containing cobalt in an electrode material at a temperature of 600 ° C. or higher, and a cutting step of cutting the roasted battery obtained in the roasting step. ,
A sieving step of sieving the cut pieces of the roasted battery obtained in this cutting step into metal scrap and roasted ash, and using a magnet from the roasted ash obtained in the sieving step to remove cobalt from the roasted ash. A magnetic separation step of magnetically separating the inclusions, an acid dissolving step of dissolving the cobalt-containing substance selected in the magnetic separation step in an acid, and a recovery step of recovering cobalt from the acid dissolved product obtained in the acid dissolving step. A method for recovering cobalt from waste secondary batteries. 2. The method for recovering cobalt from waste secondary batteries according to claim 1, wherein the recovery step is a solvent extraction step of recovering cobalt by solvent extraction. 3. The method for recovering cobalt from a secondary battery according to claim 1, wherein the roasting of the waste battery in the roasting step is performed at a temperature of 700 to 900 ° C. in a closed container or a reducing atmosphere. 4. The roasted ash obtained in the sieving step,
The method for recovering cobalt from waste secondary batteries according to claim 1, wherein the cobalt is crushed to a predetermined particle size before being subjected to magnetic separation in the magnetic separation step. 5. The method for recovering cobalt from waste secondary batteries according to claim 1, wherein the roasted ash is pulverized to an average particle size of 2 mm or less. 6. The method for recovering cobalt from waste secondary batteries according to claim 1, wherein the magnetic separation of the roasted ash in the magnetic separation step is performed by wet magnetic separation. 7. The waste secondary battery according to claim 1, wherein the weight ratio of the cobalt-containing material selected in the magnetic separation step is 0.6 or less with respect to the roasted ash before the magnetic separation. Cobalt recovery method. 8. A roasting step of roasting a waste battery of a secondary battery containing cobalt in an electrode material at a temperature of 600 ° C. or higher, and a cutting step of cutting the roasted battery obtained in the roasting step. ,
A magnetic separation step of magnetically separating the cut piece of the roasted battery obtained in this cutting step into a magnetic substance and a non-magnetic substance by a magnet, and sieving the magnetic substance obtained in this magnetic separation step to obtain a magnetic metal scrap and a cobalt-containing substance. And an acid dissolving step of dissolving the cobalt-containing substance obtained in the sieving step in an acid, and a collecting step of recovering cobalt from the acid dissolved substance obtained in the acid dissolving step. A method for recovering cobalt from waste secondary batteries, comprising: