EP-4741520-A1 - LITHIUM RECOVERY METHOD AND LITHIUM RECOVERY DEVICE

Abstract

According to the present invention, there are provided a lithium recovery method including a leaching step of adding an acidic solution containing an inorganic acid to a lithium-containing raw material and leaching lithium into the acidic solution, a precipitation step of neutralizing a first slurry obtained in the leaching step to obtain a precipitate substance, a solid-liquid separation step of performing solid-liquid separation on a second slurry obtained in the precipitation step, a washing step of washing a solid phase obtained in the solid-liquid separation step with a washing liquid, and a recycling step of reusing a post-washing liquid obtained in the washing step in either or both of the leaching step and the precipitation step, and a lithium recovery device. Further, the lithium recovery method and the lithium recovery device enable improvement of a recovery rate of lithium while impurities are reduced in a case where lithium is recovered from a lithium ion battery calcined product (black mass).

Inventors

• SATO RYOSUKE
• MURAOKA HIROKI

Assignees

• Mitsubishi Materials Corporation

Dates

Publication Date

20260513

Application Date

20240703

Claims (8)

1. A lithium recovery method comprising: a leaching step of adding an acidic solution containing an inorganic acid to a lithium-containing raw material; a precipitation step of neutralizing a first slurry obtained in the leaching step to obtain a precipitate substance; a solid-liquid separation step of performing solid-liquid separation on a second slurry obtained in the precipitation step; a washing step of washing a solid phase obtained in the solid-liquid separation step with a washing liquid; and a recycling step of reusing a post-washing liquid obtained in the washing step in either or both of the leaching step and the precipitation step.
2. The lithium recovery method according to Claim 1, wherein the lithium-containing raw material is a lithium ion battery calcined product having a particle size of 1 mm or less, which is obtained by classifying a thermally decomposed product obtained by calcining a lithium ion battery at 400°C to 600°C.
3. The lithium recovery method according to Claim 1, wherein the precipitate substance contains at least one metal selected from cobalt, nickel, and manganese.
4. The lithium recovery method according to Claim 1, wherein in the leaching step, a solid-liquid ratio (solid:liquid) of the lithium-containing raw material which is a solid component to the acidic solution which is a liquid component is 1:3 to 1:7 in terms of mass ratio.
5. The lithium recovery method according to Claim 1, wherein in the washing step, a solid-liquid ratio (solid phase:washing liquid) of the solid phase to the washing liquid is 1:2 to 1:9 in terms of mass ratio.
6. The lithium recovery method according to Claim 1, wherein a liquid phase obtained in the solid-liquid separation step is supplied in the leaching step.
7. A lithium recovery device comprising: a reaction tank that includes a lithium-containing raw material supply device, an acidic solution supply device, and a neutralizing agent supply device; a solid-liquid separation tank configured to perform solid-liquid separation on a slurry; a washing tank configured to wash a solid phase recovered from the solid-liquid separation tank; and a recycling device configured to supply a post-washing liquid recovered from the washing tank to the reaction tank.
8. The lithium recovery device according to Claim 7, wherein the reaction tank includes a leaching tank including the lithium-containing raw material supply device and the acidic solution supply device; and a neutralization tank including the neutralizing agent supply device.

Description

TECHNICAL FIELD The present invention relates to a lithium recovery method and a lithium recovery device. Priorities are claimed on Japanese Patent Application No. 2023-109269, filed July 3, 2023 and Japanese Patent Application No. 2024-107349, filed July 3, 2024, the contents of which are incorporated herein by reference. BACKGROUND ART In recent years, due to an increase in demand for lithium ion batteries, there is a concern about the depletion of lithium resources. Therefore, it has been considered to recover lithium from a lithium ion battery that is discarded due to the product life or the like and to reuse the recovered lithium. In a case of recovering lithium from a lithium ion battery, it is common to use a lithium ion battery calcined product obtained by calcining and pulverizing a lithium ion battery, which is a so-called black mass, as a recycling raw material. As a method of recovering lithium from a lithium ion battery calcined product, for example, Patent Document 1 discloses a method of adding water and an inorganic acid to a black mass to adjust the pH to be in a range of 3 to 10 and leaching water-soluble lithium in the black mass into water to recover lithium. Patent Document 2 discloses a method of leaching a black mass containing lithium aluminate in an acidic solution to recover lithium by focusing on lithium aluminate contained in the black mass. Citation List Patent Documents Patent Document 1: Japanese Patent No. 5791917(B)Patent Document 2: Japanese Patent No. 6998241(B) SUMMARY OF INVENTION Technical Problem In order to recover lithium from the black mass, lithium is usually leached from the black mass using water or an acidic solution. In the lithium recovery method disclosed in Patent Document 1, the pH is selected to prevent manganese, nickel, and cobalt in the black mass from being eluted together with lithium, and water-soluble lithium is leached into water. However, the method of Patent Document 1 has a problem in that the leaching rate of lithium into water is low for a lithium compound that is sparingly soluble in water, such as lithium fluoride (LiF) in the black mass. In Patent Document 1, it is examined that a lithium leaching step is repeatedly performed by adding a black mass to an obtained leachate in order to improve the lithium concentration in the leachate. However, the method of Patent Document 1 has a problem in that the recovery rate of lithium from the black mass is not improved. The lithium aluminate described in Patent Document 2 is sparingly soluble in water. In Patent Document 2, an acidic solution having a pH in a range of 1 to 6 is used to leach lithium aluminate from a black mass. The method of Patent Document 2 has a problem in that the leachate contains not only lithium but also valuable metals such as cobalt and aluminum. Therefore, in Patent Document 2, the leachate is neutralized to precipitate valuable metals such as cobalt and aluminum. However, the method of Patent Document 2 also has a problem in that the recovery rate of lithium from the black mass is not sufficient. The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide a lithium recovery method and a lithium recovery device that enable improvement of a recovery rate of lithium while impurities are reduced in a case where lithium is recovered from a lithium ion battery calcined product (black mass). Solution to Problem In order to solve the above-described problems, the present invention has any of the following aspects. (1) A lithium recovery method including: a leaching step of adding an acidic solution containing an inorganic acid to a lithium-containing raw material; a precipitation step of neutralizing a first slurry obtained in the leaching step to obtain a precipitate substance; a solid-liquid separation step of performing solid-liquid separation on a second slurry obtained in the precipitation step; a washing step of washing a solid phase obtained in the solid-liquid separation step with a washing liquid; and a recycling step of reusing a post-washing liquid obtained in the washing step in either or both of the leaching step and the precipitation step.(2) The lithium recovery method according to (1), in which the lithium-containing raw material is a lithium ion battery calcined product having a particle size of 1 mm or less, which is obtained by classifying a thermally decomposed product obtained by calcining a lithium ion battery at 400°C to 600°C.(3) The lithium recovery method according to (1) or (2), in which the precipitate substance contains at least one metal selected from cobalt, nickel, and manganese.(4) The lithium recovery method according to any one of (1) to (3), in which in the leaching step, a solid-liquid ratio (solid:liquid) of the lithium-containing raw material which is a solid component to the acidic solution which is a liquid component is 1:3 to 1:7 in terms of mass ratio.(5) The lithium recov