Method for recovering lithium from waste lithium iron phosphate batteries and method for recovering lithium and iron phosphate

Abstract

The invention provides a method for recovering lithium from waste lithium iron phosphate batteries, and a method for recovering lithium and iron phosphate. According to the method for recycling lithium, waste lithium iron phosphate batteries are pretreated to obtain positive and negative electrode powder, the positive and negative electrode powder reacts with water, concentrated sulfuric acid andammonia water to form a lithium-containing solution and iron-phosphorus slag, and the lithium-containing solution and the iron-phosphorus slag are separated through solid-liquid separation to obtain primary leachate and carbon-containing iron-phosphorus slag; the positive and negative electrode powder reacts with the primary leachate, concentrated sulfuric acid and ammonia water, and solid-liquidseparation is performed to obtain secondary leachate and carbon-containing iron-phosphorus slag; and an alkali is added into the obtained secondary leachate to adjust the pH value, solid-liquid separation is performed to remove impurities such as iron, aluminum and the like to obtain an impurity-removed solution, and the impurity-removed solution directly reacts with sodium carbonate to form a lithium carbonate product. According to the method, the recovery process can be simplified, the concentration of lithium in the lithium-containing solution is increased, lithium can be precipitated to generate lithium carbonate without evaporation and concentration, and the recovery rate is high; and the lithium carbonate product meets the industrial standard of lithium carbonate for batteries.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a method for recovering lithium from waste lithium iron phosphate batteries, and a method for recovering lithium and iron phosphate. Background technique [0002] Lithium iron phosphate power battery has stable chemical properties, good safety performance and long service life. At the same time, due to the low price of raw materials, it still occupies half of the power battery. In recent years, it has been widely used in various electric vehicles and energy storage fields. Behind the mass production and application means that a large number of waste lithium iron phosphate batteries are produced every year. According to the China Automobile Association's new energy vehicle production and sales data, the market inventory of lithium iron phosphate batteries is calculated, and it is estimated that the retired lithium iron phosphate batteries in 2020 will be 20.31GWh, 184,700 tons...

AI Technical Summary

Problems solved by technology

[0007] In the above-mentioned prior art, when lithium is recovered, the recovery process is long, the concentration of lithium solution is low, and it is difficult to directly precipitate lithium to prepare lithium carbonate products. After obtaining lithium solution, it is necessary to carry out other treatments such as evaporation and concentration before proceeding to the subsequent preparation of lithium carbonate. The process is complicated, the cost is high, and the recycling effect is not good

In addition, in the prior art, when lithium and iron phosphate are recovered at the same time, the synthetic iron phosphate is recovered first, and then the remaining lithium-containing solution is processed to recover lithium. The overall process is long and the recovery effect is not good.

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