Recovery method of waste lithium iron phosphate positive electrode material

Abstract

The invention provides a recovery method of a waste lithium iron phosphate positive electrode material. The method comprises the following steps: S1, adding waste lithium iron phosphate powder to a leaching agent A, slowly adding a leaching agent B, adjusting the pH value to be more than or equal to 2, and carrying out solid-liquid separation to obtain a lithium-containing leaching agent and a leaching residue; S2, adding a precipitator into the lithium-containing leachate to obtain lithium carbonate; S3, adding a first alkaline solution into the leaching residues, and filtering to obtain an aluminum-containing solution and filter residues; S4, adjusting the pH value of the aluminum-containing solution to obtain an aluminum hydroxide precipitate; S5, adding the filter residue into a firstacidic solution, performing filtering, adding a second alkaline solution into the obtained filtrate, adjusting the pH value to 2.0-2.7 to obtain basic iron phosphate, and adding phosphoric acid to obtain iron phosphate. The leaching agent A comprises a mixed solution of at least one of a weak base solution or a weak acid solution and a first oxidizing agent; and the leaching agent B comprises a mixed solution of a second acidic solution and a second oxidant. By the adoption of the method, the leaching rate of lithium is high, impurities are few, the purification and wastewater treatment cost during lithium carbonate preparation is reduced, and meanwhile iron phosphate can be efficiently recycled.

Description

technical field [0001] The application relates to the field of battery materials, in particular to a method for recycling waste lithium iron phosphate cathode materials. Background technique [0002] Lithium iron phosphate batteries have the advantages of low cost, non-toxicity, high capacity and excellent cycle performance, and are widely used in electric vehicles and energy storage industries; with the vigorous implementation of the national development of new energy policies, metal lithium and other rare The consumption of metals is increasing; at the same time, a large number of power batteries are decommissioning. It is predicted that by 2030, the number of scrapped lithium-ion batteries in the world will reach more than 11 million tons, and the world will face environmental pollution and rare metals together. Therefore, it is extremely important to invent an effective technology for recycling valuable elements in waste batteries. [0003] At present, the recovery and ...

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Problems solved by technology

[0003] At present, the recovery and regeneration of valuable metal elements in waste batteries is a relatively popular scientific research field. The main recovery methods are: hydrometallurgy, pyrometallurgy and physical restoration. Among them, hydrometallurgy has the characteristics of high element recovery rate and high purity. It is widely used, but the current recycling technology is still relatively backward. The positive and negative electrode powders obtained after physical dismantling of waste batteries often contain more impurities such as aluminum filings and iron filings, which cannot achieve high selectivity. When the lithium element in the lithium positive electrode recycling material is used, strong acids and strong oxidants are often used in element leaching, which will dissolve impurity elements, such as iron, aluminum and phosphate and other soluble metals or oxides in the lithium-containing leach solution, increasing the subsequent The cost of impurity removal, the dissolved and leached phosphate enters the waste liquid, and at the same time, iron and aluminum are easy to form colloidal precipitates to adsorb lithium elements and reduce the recovery rate of lithium elements

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