A method for recovering lithium from waste lithium iron phosphate batteries

Abstract

The application provides a method for recovering lithium from waste lithium iron phosphate batteries, comprising: roasting, crushing and screening positive and negative electrode sheets obtained by disassembling waste lithium iron phosphate batteries to obtain positive and negative electrode powders; mixing water with the positive and negative electrode powders to obtain a first slurry; adding citric acid and hydrogen peroxide to the first slurry to perform a selective leaching reaction, and performing solid-liquid separation to obtain a primary leaching solution and a primary carbon-containing iron phosphorus residue; mixing the positive and negative electrode powders with the primary leaching solution to obtain a second slurry; adding sulfuric acid and hydrogen peroxide to the second slurry to perform a leaching reaction, and performing solid-liquid separation to obtain a secondary leaching solution and a secondary carbon-containing iron phosphorus residue; adjusting the pH value of the secondary leaching solution by using an alkaline substance to perform a decontamination reaction to obtain a decontamination solution; and adding sodium carbonate to the decontamination solution to perform a lithium precipitation reaction to obtain lithium carbonate. Through stage leaching, lithium is preferentially leached by citric acid, and then a strong acid is used to break down the insoluble lithium, thereby improving the lithium recovery rate, reducing sulfuric acid consumption, and shortening the leaching time.

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