Method for recovering iron and lithium metals in positive electrode material of lithium iron phosphate battery

Abstract

The invention belongs to the field of lithium ion battery material preparation, and particularly relates to a method for recovering iron and lithium metals in a positive electrode material of a lithium iron phosphate battery. The method comprises the following steps: (1) roasting: sufficiently roasting the positive electrode material of the lithium iron phosphate battery at the roasting temperature of 400-600 DEG C; the roasting time is 2-3 hours; (2) acid leaching: soaking the roasted material which is fully roasted and oxidized in the step (1) in dilute sulfuric acid and dilute phosphoric acid solutions with the pH value range of 2.0-6.5, dissolving Li3PO4 in the roasted material, filtering, and separating the Li3PO4 from Fe2O3 and FePO4 in the roasted material; and (3) alkali precipitation: taking the filtrate treated in the step (3), and adjusting the filtrate to be alkaline, so that the Li3PO4 in the filtrate is directly precipitated into a precipitate, thereby realizing the recovery of the solid Li3PO4. In the steps of acid leaching dissolution and alkali adjustment precipitation treatment of the roasted material, only the filtrate needs to be controlled to be weakly acidic or weakly alkaline, and high-grade preferable recovery of lithium phosphate is realized in an alkali adjustment precipitation mode.

Description

technical field [0001] The invention belongs to the field of lithium ion battery material preparation, and in particular relates to a method for recovering iron and lithium metals in positive electrode materials of lithium iron phosphate batteries. Background technique [0002] In the large-scale production and recovery process of lithium iron phosphate lithium-ion batteries, the existing high-value element processes mainly include wet leaching process and solid-phase high-temperature calcination regeneration process of lithium iron phosphate. The main process of the wet leaching process is to calcine and crush waste batteries to obtain a mixture, and then use an alkaline method to remove aluminum to obtain a mixed slag of iron and lithium, and then leaching iron and lithium elements at the same time, and then selectively precipitation to obtain lithium products. [0003] In the above-mentioned wet leaching process, substances with strong oxidizing and strong acidity such as...

AI Technical Summary

Problems solved by technology

[0003] In the wet leaching process mentioned above, it is often necessary to use strong oxidizing and acidic substances such as hydrogen peroxide and sulfuric acid. High requirements and high equipment costs

Moreover, lithium elements are not preferentially leached, resulting in a large consumption of leaching acid or alkali leaching solution, and the recovery process is complicated. The recovered lithium carbonate products are often of low grade and cannot be directly used as battery materials for recycling.