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CN-122012932-A - Recycling method of ternary black powder extracted lithium slag

CN122012932ACN 122012932 ACN122012932 ACN 122012932ACN-122012932-A

Abstract

The invention provides a recycling method of ternary black powder extracted lithium slag, which comprises the following steps of mixing ternary black powder extracted lithium slag, a pH regulator, a reducing agent and a solvent at normal pressure, carrying out primary leaching reaction, carrying out solid-liquid separation to obtain primary leaching solution and primary leaching slag, mixing the primary leaching slag and acid liquor at high pressure in an oxygen atmosphere, carrying out secondary leaching reaction, carrying out solid-liquid separation to obtain secondary leaching solution and secondary leaching slag, mixing the primary leaching solution, the secondary leaching solution, an oxidizing agent and a neutralizing agent, carrying out precipitation reaction to obtain solution after iron and aluminum removal, and sequentially carrying out extraction impurity removal and extraction separation on the solution after iron and aluminum removal to obtain nickel and cobalt salt solutions respectively. The combined process solves the problem of low leaching rate of nickel, cobalt and manganese high-valence oxides in the lithium extraction slag, realizes high-efficiency separation and purification of nickel, cobalt and manganese, is economical and efficient, has short flow and has good application potential.

Inventors

  • XU KAIHUA
  • YU QING
  • ZHANG JINGXI
  • LIU LIAN
  • HU YI

Assignees

  • 荆门市格林美新材料有限公司

Dates

Publication Date
20260512
Application Date
20260226

Claims (10)

  1. 1. The recycling method of ternary black powder extracted lithium slag is characterized by comprising the following steps of: Mixing ternary black powder extracted lithium slag, a pH regulator, a reducing agent and a solvent at normal pressure, performing primary leaching reaction, and performing solid-liquid separation to obtain primary leaching liquid and primary leaching slag; mixing the first-stage leaching residue and acid liquor under high pressure in an oxygen atmosphere, performing a second-stage leaching reaction, and performing solid-liquid separation to obtain a second-stage leaching solution and a second-stage leaching residue; mixing the first-stage leaching solution, the second-stage leaching solution, an oxidant and a neutralizer, and carrying out precipitation reaction to obtain a solution after iron and aluminum removal; and sequentially carrying out extraction impurity removal and extraction separation on the solution after removing the iron and the aluminum to obtain a nickel salt solution and a cobalt salt solution respectively.
  2. 2. The recycling method according to claim 1, wherein the pH adjustor comprises concentrated sulfuric acid; preferably, the reducing agent comprises sodium metabisulfite; preferably, the mass ratio of the ternary black powder extracted lithium slag to the reducing agent is 1 (0.2-0.4).
  3. 3. The recycling method according to claim 1 or 2, wherein the step of mixing at normal pressure comprises: mixing and pulping ternary black powder extracted lithium slag and a solvent, and then adding a pH regulator and a reducing agent to obtain a mixed solution; preferably, the pH of the mixed solution is 0.5-1.5.
  4. 4. A recycling process according to any one of claims 1 to 3, characterized in that the temperature of the primary leaching reaction is 70-80 ℃; preferably, the time of the one-stage leaching reaction is 1-2 hours.
  5. 5. The recycling method according to any one of claims 1 to 4, characterized in that the acid liquid comprises sulfuric acid; preferably, the mass volume ratio of the one-stage leaching residue to the acid liquor is 100g (30-40) mL; preferably, during the high pressure mixing, the ambient pressure is 0.3-0.5MPa.
  6. 6. The recycling process according to any one of claims 1 to 5, characterized in that the temperature of the two-stage leaching reaction is 140-150 ℃; preferably, the time of the two-stage leaching reaction is 6-8 hours.
  7. 7. The recycling method according to any one of claims 1 to 6, wherein the step of mixing the primary leachate, the secondary leachate, the oxidizing agent and the neutralizing agent comprises: Mixing the first-stage leaching solution and the second-stage leaching solution to obtain a mixed leaching solution, mixing the mixed leaching solution with an oxidant, and finally adding a neutralizing agent; Preferably, the oxidizing agent comprises hydrogen peroxide; preferably, the ratio of the molar amount of iron in the mixed leachate to the molar amount of the oxidizing agent is 1 (1.2-1.8); preferably, the neutralizing agent comprises any one or a combination of at least two of sodium hydroxide, sodium carbonate or calcium oxide; preferably, the precipitation reaction is at a temperature of 65-75 ℃; preferably, the precipitation reaction time is 45-60min.
  8. 8. The recycling method according to any one of claims 1 to 7, characterized in that the step of extracting and removing impurities comprises: Carrying out first countercurrent extraction on the solution after iron and aluminum removal by adopting a first extractant to obtain an extract containing heavy metal impurities and raffinate for deeply removing the heavy metal impurities; Preferably, the first extractant comprises a P204 extractant; preferably, the saponification rate of the P204 extractant is 70-80%; Preferably, the conditions of the first countercurrent extraction comprise that the pH of the solution after iron and aluminum removal is 3-3.5, and the volume ratio of the organic phase to the aqueous phase is 1 (4-5); Preferably, the extraction liquid containing heavy metal impurities is subjected to washing treatment for selectively separating manganese to obtain a manganese-rich washing liquid.
  9. 9. The recycling method according to claim 8, wherein the step of extracting and separating nickel cobalt includes: Carrying out second countercurrent extraction on the raffinate by adopting a second extractant to obtain a cobalt-loaded organic phase and a nickel salt solution; Preferably, the second extractant comprises a P507 extractant; Preferably, the saponification rate of the P507 extractant is 80-85%; Preferably, the conditions of the second countercurrent extraction comprise that the pH of the solution after iron and aluminum removal is 5-5.5, and the volume ratio of the organic phase to the aqueous phase is 1 (1.2-1.5).
  10. 10. The recycling method according to any one of claims 1 to 9, characterized in that the recycling method comprises the steps of: (1) Mixing and slurrying ternary black powder extracted lithium slag and water according to a liquid-solid ratio (5-10): 1, then adding a pH regulator to regulate the pH of slurry to 0.5-1.5, adding a reducing agent to obtain a mixed solution, then carrying out a first-stage leaching reaction for 1-2 hours under the conditions of 70-80 ℃ and normal pressure and stirring, and carrying out solid-liquid separation after the reaction is finished to obtain a first-stage leaching solution and a first-stage leaching slag, wherein the pH regulator comprises concentrated sulfuric acid, the reducing agent comprises sodium metabisulfite, and the mass ratio of the ternary black powder extracted lithium slag to the reducing agent is 1 (0.2-0.4); (2) Mixing the primary leaching residue and sulfuric acid according to the mass volume ratio of 100g (30-40) mL, transferring into a high-pressure reaction kettle, introducing oxygen, carrying out secondary leaching reaction for 6-8h under the conditions of 140-150 ℃ and oxygen atmosphere, and carrying out solid-liquid separation after the reaction is finished to obtain secondary leaching solution and secondary leaching residue, wherein the pressure of the high-pressure reaction kettle is 0.3-0.5MPa; (3) Mixing the first-stage leaching solution and the second-stage leaching solution to obtain a mixed leaching solution, adding an oxidant into the mixed leaching solution, controlling the temperature to be 65-75 ℃, slowly adding a neutralizer to adjust the pH to be 3.8-4.2, performing precipitation reaction for 45-60min to enable iron and aluminum to hydrolyze and precipitate, and filtering to obtain an iron-aluminum removal solution, wherein the ratio of the molar quantity of iron in the mixed leaching solution to the molar quantity of the oxidant is 1 (1.2-1.8), and the neutralizer comprises any one or a combination of at least two of sodium hydroxide, sodium carbonate and calcium oxide; (4) Carrying out 4-5-level first countercurrent extraction on the solution after iron and aluminum removal by adopting a P204 extractant with the saponification rate of 70-80% to obtain an extract liquid containing heavy metal impurities and a raffinate for deeply removing the heavy metal impurities, wherein the conditions of the first countercurrent extraction comprise that the pH value of the solution after iron and aluminum removal is 3-3.5, and the volume ratio of an organic phase to a water phase is 1 (4-5), wherein the extract liquid containing the heavy metal impurities comprises copper ions, zinc ions, manganese ions, calcium ions and magnesium ions; (5) Performing a second countercurrent extraction of the raffinate at a level of 6-7 by using a P507 extractant with a saponification rate of 80-85% to obtain a cobalt-loaded organic phase and a nickel sulfate solution, wherein the second countercurrent extraction condition comprises that the pH value of the solution is 5-5.5 after iron and aluminum are removed, and the volume ratio of the organic phase to the water phase is 1 (1.2-1.5); carrying out back extraction on the organic phase loaded with cobalt by adopting dilute sulfuric acid to obtain a cobalt sulfate solution, wherein the concentration of the dilute sulfuric acid is 1.5-2.5mol/L; (6) Concentrating the nickel sulfate solution and the cobalt sulfate solution to specific gravity of 1.55-1.65g/cm 3 respectively, cooling and crystallizing at the speed of 5-10 ℃ per hour, and drying to obtain battery grade nickel sulfate and battery grade cobalt sulfate respectively.

Description

Recycling method of ternary black powder extracted lithium slag Technical Field The invention belongs to the technical field of recycling and recovery of waste lithium ion batteries, and particularly relates to a recycling method of ternary black powder extracted lithium slag. Background At present, the efficient recovery of the waste lithium ion battery, particularly the ternary positive electrode material rich in valuable metals such as nickel, cobalt, manganese and the like, becomes a necessary requirement for realizing sustainable utilization of resources and environmental protection. In the recovery process of the ternary positive electrode material, lithium element is generally extracted through hydrometallurgy, and the generated 'lithium extraction slag' becomes a main carrier for enriching core strategic metals such as nickel, cobalt, manganese and the like. How to economically and efficiently recover these valuable metals from such lithium extraction slag and directly convert them into high value-added battery grade products is a core technical challenge in the current resource recycling field. The nickel, cobalt and manganese in the lithium extraction slag are present in the form of high-valence oxides, the chemical stability of the compounds is strong, the lattice structure is compact, the structure is difficult to be destroyed by the traditional normal pressure leaching process, the leaching rate of metals is generally low, and a large amount of valuable metals are retained in the slag to cause waste. In order to improve leaching efficiency, chemical reducing agents such as sodium sulfite, iron powder and the like are mostly adopted in the prior art to strengthen leaching, but the reducing agents have the problems of large consumption and high cost, new impurities (such as iron ions) are easy to introduce, the subsequent purification burden is increased, and the process flow is long and the economical efficiency is poor. In addition, in the subsequent treatment of the leaching solution, the prior art is often focused on preliminary enrichment of metals, so that high-efficiency separation and deep purification of nickel, cobalt, manganese and other impurity elements commonly coexisting in the leaching solution are difficult to realize, and if the impurity elements cannot be effectively removed, the purity of a final product can be seriously influenced, so that the purity of the final product is difficult to reach the battery level standard, and the high-value application of the recovered product of the extracted lithium slag is limited. Therefore, how to solve the problem that the leaching rate is low due to the difficulty in leaching the high-valence oxides of nickel, cobalt and manganese in the lithium extraction slag in an economic and efficient way, realize the efficient separation and purification of the nickel, cobalt and manganese, shorten the preparation process flow of battery-grade products and become the hot spot direction of the current research. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide a recycling method of ternary black powder extracted lithium slag. The invention solves the problem that the leaching rate is low because of difficult leaching of high-valence oxides of nickel, cobalt and manganese in the lithium extraction slag by the combined process of normal pressure reduction acid leaching, oxygen pressure leaching, extraction impurity removal and extraction separation, and realizes the high-efficiency separation and deep purification of nickel, cobalt and manganese, and the obtained nickel salt solution and cobalt salt solution can be directly used for preparing battery grade products. The combined process is economical and efficient, greatly shortens the preparation process flow from ternary black powder to battery grade products, has less energy consumption and equipment investment, and has good application potential. In order to achieve the aim of the invention, the invention adopts the following technical scheme: the invention provides a recycling method of ternary black powder extracted lithium slag, which comprises the following steps: Mixing ternary black powder extracted lithium slag, a pH regulator, a reducing agent and a solvent at normal pressure, performing a first-stage leaching reaction, and performing solid-liquid separation to obtain a first-stage leaching solution and a first-stage leaching slag. And in the oxygen atmosphere, mixing the primary leaching residues with acid liquor at high pressure, carrying out secondary leaching reaction, and carrying out solid-liquid separation to obtain secondary leaching liquid and secondary leaching residues. And mixing the first-stage leaching solution, the second-stage leaching solution, the oxidant and the neutralizer, and performing precipitation reaction to obtain solution after iron and aluminum removal. And sequentially carrying out extraction impurity removal and ext