Method for recovering lithium from lithium iron phosphate waste and application thereof

Abstract

The invention belongs to the technical field of lithium ion battery material recovery, and discloses a method for recovering lithium from lithium iron phosphate waste and an application thereof, wherein the method comprises the following steps: (1) adding water into the lithium iron phosphate waste to prepare slurry to obtain lithium iron phosphate slurry; (2) adding soluble iron salt into the lithium iron phosphate slurry, reacting, and filtering to obtain filtrate containing Li<+> and Fe<2+> and iron phosphate slag; (3) adding an oxidizing agent into the filtrate, and filtering to obtain filtrate containing Li<+> and Fe<3+> and ferric hydroxide; and (4) carrying out multistage countercurrent circulation leaching on the filtrate and lithium iron phosphate battery powder to obtain a lithium solution. According to the method, the soluble ferric salt is adopted, the soluble ferric salt belongs to strong acid and weak base salt, the conversion of lithium iron phosphate can be accelerated, and the direct recovery rate of the primary conversion iron phosphate slag is about 98.5% and the direct recovery rate of lithium is about 98.5% by combining the oxidation of the oxidant.

Description

technical field [0001] The invention belongs to the technical field of lithium ion battery material recovery, and in particular relates to a method for recovering lithium from lithium iron phosphate waste and its application. 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] At present, there are two recycling technologies for the positive electrode materials of waste lithium iron phosphate batteries: pyrometallurgy and hydrometallurgy. In terms of pyrometallurgy, the main method is to repair lithium iron phosphate to achieve secondary utilization. This method has complicated procedures, high energy consumpt...

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Problems solved by technology

In the related technology, lithium iron phosphate waste is re-prepared into lithium iron phosphate material by heat treatment-acid leaching-sinking iron phosphate-sinking lithium carbonate-lithium iron phosphate synthesis process, but due to the complexity of raw material components in this process, A large number 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 lithium carbonate recovered by this method is difficult to guarantee

In the related technology, oxidation roasting-phosphoric acid leaching-liquid-solid separation-precipitation lithium carbonate process is used to achieve efficient separation of lithium and phosphorus iron, and the effect is good, but the recovery of phosphorus resources and the consumption of acid are not considered, and the cost is high

In the related art, waste lithium iron phosphate batteries are sorted to obtain lithium-containing positive electrode powder, a certain amount of acid is added to the lithium-containing powder to control the pH to 2.5-6.5, and lithium sulfate solution and iron phosphate precipitation are obtained. Lithium sulfate is used to prepare Lithium phosphate and iron phosphate precipitation are calcined to obtain iron orthophosphate. This method has a simple process and a high lithium recovery rate. However, this method still uses the traditional acid immersion wet process, which consumes acid and costs a lot.

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