A method for selectively extracting lithium from waste lithium iron phosphate materials

Abstract

The invention discloses a method for selectively extracting lithium from a waste lithium iron phosphate material, which comprises the following steps: immersing the waste lithium iron phosphate material in a sodium hydroxide solution, carrying out alkali leaching to remove aluminum, filtering, and removing aluminum from the filtered The material is dried to obtain lithium iron phosphate powder, and the filtered sodium aluminate filtrate is recovered; the lithium iron phosphate powder is put into a heating furnace, and the selective lithium extraction gas is introduced, and then roasted to obtain iron phosphate and lithium The compound of iron phosphate and lithium is added to the ball mill, wet ball milled, and filtered to obtain iron phosphate solid and lithium-containing solution respectively; the pH value of the lithium-containing solution is adjusted to 9.0‑11.0, and impurities are removed to obtain pure lithium solution; adding sodium carbonate solution to pure lithium solution for reaction, filtering, washing and drying the filtered solid to obtain lithium carbonate. The lithium in the waste lithium iron phosphate material is recovered by the method of the invention, and the recovery rate of the lithium is as high as 95 percent or more.

Description

technical field [0001] The invention belongs to the technical field of comprehensive utilization of lithium ion battery electrode materials, and in particular relates to a method for selectively extracting lithium from waste lithium iron phosphate materials. Background technique [0002] Lithium iron phosphate is currently the most widely used lithium-ion battery material, and is regarded by many industry insiders as the future development direction of lithium batteries. Since the 21st century, with the blowout development of the lithium battery new energy market, the problem of disposing of waste lithium iron phosphate batteries has become increasingly prominent. [0003] Currently the most reported LiFePO 4 The waste treatment process is mainly borrowed from waste recycling processes such as lithium cobalt oxide and lithium nickel cobalt manganese oxide. Invention patent CN104953200A (method for recycling battery-grade iron phosphate in lithium iron phosphate batteries a...

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Problems solved by technology

Invention patent CN104953200A (method for recycling battery-grade iron phosphate in lithium iron phosphate batteries and using waste lithium iron phosphate batteries to prepare lithium iron phosphate cathode materials) heat treatment-acid leaching-precipitated iron phosphate-precipitated lithium carbonate-phosphoric acid Lithium iron synthesis process, re-preparation of lithium iron phosphate waste into lithium iron phosphate material, but due to the complex composition of raw materials in this process, a large amount of impurities (such as aluminum) will be included in iron phosphate, which will affect the performance of the synthesized lithium iron phosphate material , and the lithium recovery rate of this method reclaims lithium carbonate is difficult to guarantee

Invention patent CN106450547A (a method for recovering iron phosphate and lithium carbonate from lithium iron phosphate waste) adopts oxidation roasting-phosphoric acid leaching-liquid-solid separation-precipitation lithium carbonate process to achieve efficient separation of lithium and phosphorus iron with good effect. But the process is cumbersome