JP7232119B2 - Method for processing lithium-ion battery waste and method for producing sulfate - Google Patents

Description

This specification discloses a technology related to a method for treating lithium ion battery waste and a method for producing sulfate.

In recent years, valuable metals such as cobalt and nickel contained in lithium-ion battery waste containing positive electrode materials from lithium-ion secondary batteries discarded due to product life, manufacturing defects, or other reasons have been recovered by wet processing. , has been widely studied from the viewpoint of effective utilization of resources.

For example, in order to recover valuable metals from lithium ion battery waste, battery powder or the like obtained through roasting or other predetermined processes is usually added to acid and leached, and the lithium, nickel, and cobalt that may be contained therein are extracted. , manganese, iron, copper, aluminum, etc. are dissolved in an acidic solution.

After that, iron, copper and aluminum among the metal elements dissolved in the acidic solution are sequentially or simultaneously removed by multiple steps of solvent extraction or neutralization, and nickel, cobalt, manganese and lithium are removed. Valuable metals are separated and concentrated by solvent extraction to obtain a solution in which each metal is dissolved. Nickel and cobalt are recovered from each solution by electrolysis or the like (see Patent Documents 1 to 3, for example).

JP 2010-180439 A U.S. Patent Application Publication No. 2011/0135547 Japanese Patent No. 5706457

By the way, in the process of recovering metals from lithium-ion battery waste, if it is possible to recover high-purity cobalt, nickel, and manganese in the form of compounds with predetermined inorganic acids such as sulfates, those compounds can be converted into lithium It becomes possible to use it for the production of ion batteries. This is desirable in aiming for a recycling-oriented society that efficiently reuses finite resources.

Here, in the recovery process described above, the aluminum dissolved in the acidic solution is separated and removed by neutralization or solvent extraction. However, neutralization or the like cannot sufficiently lower the concentration of aluminum in the liquid. Therefore, in this case, it is difficult to obtain high purity cobalt, nickel and manganese compounds for lithium ion battery production.

This specification discloses a method for treating lithium-ion battery waste and a method for producing sulfate, which can effectively separate and remove aluminum impurities.

The method for treating lithium ion battery waste disclosed in this specification is obtained by subjecting lithium ion battery waste to wet treatment, in which an acid solution in which at least cobalt, nickel, manganese and aluminum are dissolved is diluted to pH 4.0. After the preceding neutralization step of neutralizing to 0 to 6.0, precipitating part of the aluminum, and removing part of the aluminum by solid-liquid separation, and the preceding neutralization step, the pH is adjusted to 11.0 or more. a post-neutralization step of neutralizing, leaving the remainder of the aluminum in the liquid, and obtaining a neutralization residue containing cobalt, nickel and manganese by solid-liquid separation.

The method for producing sulfate disclosed in this specification uses the method for treating lithium ion battery waste described above to produce sulfate containing cobalt, nickel and manganese.

According to the method for treating lithium-ion battery waste described above, aluminum as an impurity can be effectively separated and removed.

1 is a flow diagram illustrating a method for treating lithium ion battery waste according to one embodiment; FIG. FIG. 2 is a flowchart showing details of the pretreatment and wet treatment of FIG. 1;

An embodiment of a method for treating lithium ion battery waste will be described in detail below.
In a method for treating lithium ion battery waste according to one embodiment, as shown in FIG. Including performing the sum process. This acidic solution contains dissolved at least cobalt, nickel, manganese and aluminum.

In the first-stage neutralization step, the pH is neutralized to 4.0 to 6.0 to precipitate part of the aluminum, and the part of the aluminum is removed by solid-liquid separation. In the post-neutralization step, after the pre-neutralization step, the pH is neutralized to 11.0 or more, the aluminum residue is left in the liquid, and a neutralization residue containing cobalt, nickel and manganese is obtained by solid-liquid separation.

When iron is further dissolved in the acidic solution, as shown in FIG. 1, before the former neutralization step or between the former neutralization step and the latter neutralization step, the pH is adjusted to 3 under the supply of an oxidizing agent. .0 to 4.0, an oxidation step can be further performed to precipitate iron and remove iron by solid-liquid separation.

(Lithium-ion battery waste)
The target lithium-ion battery waste is a lithium-ion secondary battery that can be used in mobile phones and various other electronic devices, and is discarded due to the life of the battery product, manufacturing defects, or other reasons. Recovering valuable metals from such lithium-ion battery waste is preferable from the viewpoint of effective utilization of resources. Another object of the present invention is to recover valuable metals such as cobalt and nickel with high purity so that they can be reused in the manufacture of lithium ion secondary batteries.

Lithium-ion battery waste has a housing containing aluminum as an outer covering that wraps around it. Examples of this housing include those made only of aluminum, those containing aluminum and iron, aluminum laminates, and the like. In addition, the lithium-ion battery waste contains a single metal oxide selected from the group consisting of lithium, nickel, cobalt, and manganese, or a positive electrode active material composed of two or more composite metal oxides, etc., in the above housing. The material, or cathode active material, may include aluminum foil (cathode substrate) that is coated and adhered by, for example, polyvinylidene fluoride (PVDF) or other organic binder or the like. In addition, lithium ion battery waste may contain copper, iron, and the like. Additionally, lithium ion battery waste typically contains an electrolyte within the housing. As the electrolytic solution, for example, ethylene carbonate, diethyl carbonate, etc. may be used.

(Preprocessing)
Pretreatment for lithium ion battery waste may include roasting, crushing and sieving steps, as shown in FIG.

In the roasting step, the above lithium ion battery waste is heated. This roasting step is performed for the purpose of, for example, changing metals such as lithium and cobalt contained in the lithium ion battery waste into a form that is easily dissolved. In the roasting step, it is suitable to heat the lithium ion battery waste, for example, at a temperature range of 450° C. to 1000° C., preferably 600° C. to 800° C., for 0.5 hour to 4 hours. This roasting step can be performed using various heating equipment such as a rotary kiln, various other furnaces, and a furnace that performs heating in an air atmosphere.

After the roasting step, a crushing step can be performed to remove the positive and negative electrode materials from the housing of the lithium ion battery waste. The crushing step is performed to break the casing of the lithium ion battery waste and selectively separate the positive electrode active material from the aluminum foil coated with the positive electrode active material.
Here, various known apparatuses or devices can be used, but it is particularly preferable to use an impact pulverizer capable of crushing the lithium ion battery waste by applying impact while cutting. A sample mill, a hammer mill, a pin mill, a wing mill, a tornado mill, a hammer crusher and the like can be cited as examples of the impact type crusher. A screen can be installed at the outlet of the crusher, and the lithium ion battery waste is discharged from the crusher through the screen after being crushed to a size that can pass through the screen.

After crushing the lithium ion battery waste in the crushing process, the lithium ion battery scrap is sieved using a sieve of suitable mesh size to remove, for example, aluminum powder. As a result, it is possible to obtain powdery or granular lithium-ion battery waste from which aluminum and copper remain on the sieve and aluminum and copper are removed to some extent under the sieve.

(Wet processing)
Subsequent wet treatment includes, as shown in FIG. It may comprise an acid leaching step of leaching the waste into an acid to obtain said acid solution.

In the lithium dissolving step, the pretreated lithium ion battery waste is brought into contact with water to dissolve the lithium contained therein. This allows the lithium contained in the lithium ion battery waste to be separated at an early stage in the recovery process. The water used here can be tap water, industrial water, distilled water, purified water, ion-exchanged water, pure water, ultrapure water, or the like. The water to be brought into contact with the lithium ion battery waste may be made into an acidic aqueous solution by adding an acid such as sulfuric acid. The liquid temperature at the time of contact between the lithium ion battery waste and water or the acidic aqueous solution can be 10°C to 60°C. Since the lower the liquid temperature, the higher the solubility of lithium carbonate, the lower the liquid temperature is, the better. Pulp consistency can be from 50 g/L to 150 g/L. This pulp density means the ratio of the dry weight (g) of the lithium ion battery waste to the amount (L) of water or the like with which the lithium ion battery waste is brought into contact.

In the acid leaching step, the lithium-ion battery waste from which lithium has been separated in the lithium dissolving step is added to an acid such as sulfuric acid for leaching. The acid leaching step can be performed by a known method or conditions, but the pH is set to 0.0 to 2.0, and the oxidation-reduction potential (ORP value, based on silver/silver chloride potential) is set to 0 mV or less. preferred.

Thereby, an acidic solution in which at least cobalt, nickel, manganese and aluminum are dissolved is obtained. The acidic solution may further contain dissolved therein at least one selected from the group consisting of iron, phosphorus and fluorine.
For example, the acid solution has a cobalt concentration of 1 g/L to 30 g/L, a nickel concentration of 1 g/L to 50 g/L, a manganese concentration of 1 g/L to 50 g/L, and an aluminum concentration of 0.010 g/L to 10 g/L. L, the iron concentration can be from 0.1 g/L to 5 g/L.

(Pre-stage neutralization step)
A pre-stage neutralization step is performed for the acidic solution described above. In the first stage neutralization step, an alkali is added to the acidic solution to neutralize it to pH 4.0 to 6.0. This causes some of the aluminum dissolved in the acid solution to precipitate. Then, by solid-liquid separation using a filter press, a thickener, or the like, the residue containing part of the aluminum can be removed.

In the pre-neutralization step, if the pH is too low, aluminum cannot be precipitated sufficiently, while if the pH is too high, other metals such as cobalt will also precipitate. From this point of view, the pH in the first stage neutralization step is more preferably 4.0 to 6.0, more preferably 4.5 to 5.0.
In the first stage neutralization step, an alkali such as sodium hydroxide, sodium carbonate, or ammonia can be added to the acidic solution in order to increase the pH within the range described above.

In the pre-neutralization step, the oxidation-reduction potential (ORPvsAg/AgCl) of the acidic solution, that is, the ORP value is preferably −500 mV to 100 mV, more preferably −400 mV to 0 mV. If the ORP value at this time is too high, cobalt may precipitate as tricobalt tetroxide (Co ₃ O ₄ ). There is concern that it will be reduced and precipitated.

It is preferable to set the liquid temperature to 50°C to 90°C in the first stage neutralization step. That is, if the liquid temperature is less than 50°C, there is a concern that the reactivity may deteriorate, and if it is higher than 90°C, a device that can withstand high heat is required, and it is also preferable from a safety point of view. do not have. Therefore, the liquid temperature is preferably 60°C to 90°C.

In the former neutralization step, the concentration of aluminum in the liquid is preferably 30 mg/L to 50 mg/L. This aluminum concentration can be maintained until after the post-neutralization step, and the remainder of the aluminum can be discarded as an aluminum-containing liquid after the post-neutralization step.

(Oxidation process)
When iron is contained in the acidic solution, as shown in FIG. 1, an oxidation step can be performed before the above-described former neutralization step or between the former neutralization step and the later-described latter neutralization step. However, this oxidation step may be omitted.

In the oxidation step, an oxidizing agent is added to the acidic solution before the neutralization step or after the neutralization step, and the pH is adjusted within the range of 3.0 to 4.0 to remove iron in the liquid. to precipitate. After that, the precipitated iron can be removed by solid-liquid separation.

In the oxidation step, the iron in the liquid is oxidized from bivalent to trivalent iron by adding an oxidizing agent. Here, since trivalent iron precipitates as an oxide or hydroxide at a pH lower than that of divalent iron, iron can be precipitated by adjusting the pH to a relatively low value as described above. . Iron often precipitates as a solid such as iron hydroxide (Fe(OH) ₃ ).
Here, if the pH is increased significantly, precipitation of cobalt is caused. On the other hand, in this oxidation step, iron can be precipitated without raising the pH so much, so the precipitation of cobalt at this time can be effectively suppressed.

In the oxidation process, if the pH is too low, iron cannot be precipitated sufficiently, while if the pH is too high, other metals such as cobalt will also precipitate. From this point of view, the pH in the oxidation step is more preferably 3.0 to 4.0, more preferably 3.0 to 3.5.

In the oxidation step, the ORP value is preferably 300 mV to 900 mV, more preferably 500 mV to 700 mV. If the ORP value at this time is too low, iron may not be oxidized, while if the ORP value is too high, cobalt may be oxidized and precipitated as an oxide.

In the oxidation step, an acid such as sulfuric acid, hydrochloric acid, or nitric acid can be added to the first post-separation liquid in order to lower the pH to the range described above prior to the addition of the oxidizing agent.
The oxidizing agent is not particularly limited as long as it can oxidize iron, but is preferably manganese dioxide, a positive electrode active material, and/or a manganese-containing leaching residue obtained by leaching a positive electrode active material. They can effectively oxidize iron. The manganese-containing leaching residue obtained by leaching the positive electrode active material with an acid or the like may contain manganese dioxide. When the positive electrode active material or the like is used as the oxidizing agent, a precipitation reaction occurs in which manganese dissolved in the liquid becomes manganese dioxide, so the precipitated manganese can be removed together with iron.

After adding the oxidizing agent, an alkali such as sodium hydroxide, sodium carbonate, or ammonia can be added to adjust the pH to a predetermined range.

(Later neutralization step)
After the former neutralization process or after the oxidation process, the latter neutralization process is performed. In the post-neutralization step, alkali is added to neutralize the pH to 11.0 or higher, leaving the remainder of the aluminum in the liquid while precipitating cobalt, nickel and manganese. Then, by solid-liquid separation, a neutralization residue containing cobalt, nickel and manganese can be obtained by separating it from the aluminum-containing liquid.

In neutralization, it is difficult to precipitate enough aluminum while limiting losses of cobalt, nickel and manganese. Therefore, in this pre-neutralization step, the cobalt, nickel and manganese to be recovered are precipitated, and the remainder of the aluminum that was not precipitated in the pre-neutralization step is dissolved and left in the liquid. This makes it possible to separate almost all aluminum from cobalt, nickel and manganese.

Here, by setting the pH to 11.0 or higher, aluminum can be effectively left in the liquid. If the pH is less than 11.0, the remainder of aluminum precipitates and is included in the neutralization residue together with cobalt and the like, and sufficient separation cannot be achieved. From this point of view, it is preferable to set the pH to 11.0 or higher in the former neutralization step. On the other hand, if the pH is too high, there is concern about a useless increase in cost, so the pH is preferably 12.0 or less, more preferably 11.5 or less.

The ORP value in the post-neutralization step is preferably 500 mV to 1400 mV, more preferably 700 mV to 1200 mV. If the ORP value here is too large, there is a concern that cobalt and the like will become oxides, and if it is too small, there is a risk of poor oxidation of iron.
The liquid temperature in the latter neutralization step can be 60°C to 90°C.

By performing the post-neutralization step under such conditions, the concentration of aluminum in the liquid in the pre-neutralization step can be maintained until the post-neutralization step. Therefore, the solid-liquid separation in the post-neutralization step can effectively remove the remaining aluminum as the aluminum-containing liquid.

The neutralization residue obtained by solid-liquid separation in the post-neutralization step usually contains cobalt, nickel and manganese as hydroxides. Thus, the neutralization residue may contain cobalt hydroxide, nickel hydroxide and manganese hydroxide. Further, the _{neutralization} residue may contain oxides of _each metal such _{as Co3O4, Mn3O4 , Mn2O3 , Ni3O4 .}

(Washing process)
The neutralization residue can be subjected to a washing step as necessary. In the washing step, the neutralization residue is immersed in pure water or other water, or otherwise brought into contact with water to dissolve sodium that may be contained in the neutralization residue. At this time, phosphorus and/or fluorine that may be contained in the neutralization residue may also be eluted. In addition, you may stir on this occasion. Then, by solid-liquid separation, sodium and the like can be removed as a sodium-containing liquid.

It is preferable that the liquid temperature during washing is 0° C. to 100° C., and the washing time is 0.01 hour to 24 hours. The washing operation can be performed once or multiple times.

(Melting process)
In the dissolving step, the neutralization residue is dissolved in a sulfuric acid acid solution, and then the sulfuric acid acid solution in which the neutralization residue is dissolved is concentrated by heating or cooled. By subjecting this to solid-liquid separation, a sulfate containing cobalt, nickel and manganese can be obtained.

The sulfuric acid acid solution in which the neutralization residue is dissolved can be concentrated by heating to, for example, 30°C to 100°C, preferably 80°C. Alternatively, the sulfuric acid acid solution may be cooled to eg -20°C to 10°C, preferably 0°C. This results in precipitation of sulfate containing cobalt, nickel and manganese.

The resulting sulphate contains a mixture of cobalt sulphate, nickel sulphate and manganese sulphate. This sulfate has sufficiently reduced impurity grades, for example, a sodium grade of 20 mass ppm or less, an iron grade of 5 mass ppm or less, and an aluminum grade of 10 mass ppm or less. Therefore, such complex salts can be effectively used in the production of lithium ion batteries.

The cobalt grade of the sulfate is, for example, 1% by mass to 5% by mass, preferably 2% by mass to 3% by mass. Also, the nickel grade is, for example, 1% by mass to 10% by mass, preferably 3% by mass to 6% by mass. Also, the manganese grade is, for example, 1% by mass to 10% by mass, preferably 3% by mass to 6% by mass.
The treatment methods described above may, for example, result in a cobalt recovery of 96%, a nickel recovery of 98.6%, and a manganese recovery of 99%. This recovery rate is based on the content of each metal in the liquid obtained by leaching the raw material with sulfuric acid, using an intermediate product obtained from lithium ion battery waste as a raw material. It is calculated by subtracting the transferred loss.

Next, the method for treating lithium ion battery waste described above was carried out on a trial basis, and the effect was confirmed, which will be described below. However, the description herein is for illustrative purposes only and is not intended to be limiting.

Lithium ion battery waste is pretreated by roasting, crushing, and sieving, and is subjected to wet treatment of lithium dissolution and acid leaching to obtain Ni: 5 g/L, Co: 25 g/L, Mn: 1 g/L. An acidic solution having a composition of L, Fe: 0.050 g/L, and Al: 0.100 g/L was obtained.
This acidic solution was subjected to a pre-neutralization step with an ORP of −300 mV (Ag/AgCl) and a pH of 5.0 to convert Al into a hydroxide of Al(OH) ₃ for solid-liquid separation. Al concentration was reduced from 1800 mg/L to 30 mg/L at this stage.

Then, as an oxidation step, ORP: 400 mV (Ag/AgCl), pH 4.0, Fe was converted to hydroxide of Fe(OH) ₃ and removed by solid-liquid separation. This brought the Fe concentration from 360 mg/L to <1 mg/L. At this time, the Al concentration remained at 30 mg/L.

Thereafter, as a post-neutralization step, ORP: 400 mV (Ag/AgCl), pH 11.0, Co, Ni, and Mn are changed to Co(OH) ₂ , Ni(OH) ₂ , and Mn(OH) ₂ to obtain a solid-liquid separated. At this time, since the Al solubility at pH 11.0 is 800 mg/L, Al was dissolved in the liquid at a concentration of 30 mg/L.
The neutralization residue containing hydroxide obtained by solid-liquid separation was washed with pure water to remove sodium from the neutralization residue.

After that, the neutralization residue was dissolved in sulfuric acid and heated and concentrated to obtain a sulfate salt containing Co, Ni and Mn and containing few impurities. The sulfate was Na<20 wt ppm, Fe<5 wt ppm, Al<10 wt ppm, and was battery grade.

Claims (9)

A method of treating lithium ion battery waste comprising:
For an acidic solution obtained by subjecting lithium-ion battery waste to wet treatment and in which at least cobalt, nickel, manganese and aluminum are dissolved,
a preceding neutralization step of neutralizing the pH to 4.0 to 6.0, precipitating a portion of the aluminum, and removing a portion of the aluminum by solid-liquid separation;
After the former neutralization step, the pH is neutralized to 11.0 or more, the remainder of aluminum is left in the liquid, and the latter neutralization step is performed to obtain a neutralization residue containing cobalt, nickel and manganese by solid-liquid separation. A method of treating lithium ion battery waste, comprising: The acidic solution further contains dissolved iron,
Before the former neutralization step or between the former neutralization step and the latter neutralization step, the pH is adjusted to 3.0 to 4.0 under the supply of an oxidizing agent to precipitate iron, and the iron is precipitated by solid-liquid separation. 2. The method of treating lithium ion battery waste according to claim 1, further comprising performing an oxidation step to remove . 3. The method for treating lithium ion battery waste according to claim 1, wherein the neutralization residue obtained in the post-neutralization step contains cobalt hydroxide, nickel hydroxide and manganese hydroxide. The lithium ion battery according to any one of claims 1 to 3, wherein the aluminum concentration in the liquid is set to 30 mg/L to 50 mg/L in the pre-neutralization step, and the aluminum concentration is maintained until after the post-neutralization step. Waste disposal method. The wet treatment includes a lithium dissolving step of dissolving lithium in the lithium ion battery waste after a roasting step of roasting the lithium ion battery waste with water or an acidic aqueous solution, and a lithium dissolving step. The method for treating lithium ion battery waste according to any one of claims 1 to 4, comprising an acid leaching step of leaching the separated lithium ion battery waste with an acid to obtain the acidic solution. After the latter neutralization step, the method further comprises a dissolving step of dissolving the neutralization residue in a sulfuric acid acidic solution, heating and concentrating or cooling the sulfuric acid acidic solution, and obtaining a sulfate containing cobalt, nickel and manganese by solid-liquid separation. The method for treating lithium ion battery waste according to any one of claims 1 to 5. The neutralization residue contains sodium,
7. The method for treating lithium ion battery waste according to claim 6, further comprising a washing step of washing the neutralized residue to remove sodium from the neutralized residue between the post-neutralization step and the dissolving step. . 8. The method for treating lithium ion battery waste according to claim 6, wherein the aluminum grade of said sulfate is 10 ppm by mass or less. A method for producing sulfate, comprising producing a sulfate containing cobalt, nickel and manganese using the method for treating lithium ion battery waste according to any one of claims 6 to 8.

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