Method for producing lithium-rich pure solution from waste lithium ion battery positive electrode active material

Abstract

The invention discloses a method for producing a lithium-rich pure solution from a waste lithium ion battery positive electrode active material, belongs to the technical field of waste lithium ion battery material recycling, and particularly provides a method for producing a lithium-rich pure solution from a reduced sulfuric acid leaching solution of a positive electrode active material. A high-sodium and low-lithium lithium sulfate solution obtained after the positive electrode active material is subjected to reduction leaching and leaching solution purification is subjected to lithium deposition with phosphoric acid or phosphate to obtain lithium-containing phosphate enrichment; lithium is selectively leached out from the lithium-containing phosphate enrichment by using less than a theoretically required amount of a calcium chloride solution to obtain the lithium-rich pure solution and lithium-containing phosphorus-calcium residues; and the lithium-containing pure solution is used for producing a product such as battery-grade lithium carbonate or lithium chloride through a conventional method such as deposition or crystallization, and a solution obtained after the lithium-containing phosphorus-calcium residues are subjected to sulfuric acid leaching and neutralization returns to the lithium deposition step for cyclic use. According to the method, the lithium-rich pure solution can be directly produced from the high-sodium and low-lithium solution without pre-concentration, the energy consumption and the cost are low, and the lithium recycling rate is high.

Description

technical field [0001] The invention belongs to the technical field of recycling waste lithium ion battery materials, and in particular relates to a method for producing lithium-rich net liquid from the positive electrode active material of waste lithium ion batteries. Background technique [0002] Due to its high working voltage and specific energy, stable discharge voltage, light weight and small size, long cycle life, and no memory effect, lithium-ion batteries are widely used in portable devices, electric vehicles, power reserves, satellites and other fields. With the advancement of lithium-ion battery technology and the increase in output, its waste is also increasing year by year. The lifespan of lithium-ion batteries is generally 3 to 5 years. At present, the recycling system has not yet reached a large scale, and the recovery rate is low. Most of the waste lithium-ion batteries have not been effectively treated, which not only pollutes the environment, but also waste...

AI Technical Summary

Problems solved by technology

There are roughly two routes for the treatment of the leachate. One is to purify the leachate to remove harmful impurities such as iron and aluminum, and then directly precipitate to prepare the precursor of the positive electrode material. The precursor is returned to the battery company for utilization, and the precipitation method is used to produce the precursor. The process flow is short, but the product market is narrow, and the ingredients need to be adjusted to meet the production requirements of battery materials, and the consumption of acid-base neutralization reagents is large, and the precursors are washed repeatedly, resulting in a large amount of washing water and high sodium ions in the solution after precipitation , the concentration of lithium ions is low, resulting in high energy consumption for lithium recovery

Another solution is to purify the leaching solution to remove impurities such as iron and aluminum, then continue to extract and separate the purified solution to prepare nickel salt and cobalt salt, and recover lithium salt products from the raffinate after nickel and cobalt extraction. The lithium concentration in the raffinate is low and contains a large amount of sodium ions. To prepare lithium carbonate products, it is necessary to use evaporation and concentration for enrichment and then carbonate precipitation. Evaporation and concentration of low-concentration lithium salt solutions require high energy consumption. The sodium ion content in the residual liquid is high, resulting in the crystallization of a large amount of sodium salt and the entrainment loss of lithium salt during the concentration process, and resulting in high sodium content in subsequent lithium salt products, which require further purification to obtain battery-grade products

Moreover, the solubility product of lithium carbonate is large, the recovery rate of lithium carbonate precipitation is low, the lithium precipitation rate is less than 80%, and the lithium content after precipitation is still more than 2g / L

In addition, due to the use of a large amount of reducing agents such as hydrogen peroxide, which is expensive and difficult to transport and store during leaching, the cost of comprehensive utilization of waste lithium-ion battery cathode materials is high.

[0004] In addition, K, Na, Ca, and Mg are common impurities in the production of battery-grade lithium salts. Due to their similar chemical properties to Li, they are difficult to remove in the production of lithium salts, which is a difficult point in the study of lithium salt purification.

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