Method for recovering lithium from lithium iron phosphate

Abstract

The invention discloses a method for recovering lithium from lithium iron phosphate. The method disclosed by the invention comprises the following steps: dissolving waste lithium iron phosphate slag with sulfuric acid and ferric sulfate, leaching iron, lithium and phosphorus, adding an oxidizing agent, reacting iron and phosphate radicals to produce an iron phosphate precipitate and a small amountof ferric hydroxide, converting lithium into a water-soluble lithium sulfate solution, filtering to obtain the lithium sulfate solution, adding sodium carbonate into the lithium sulfate solution to prepare a lithium carbonate product, and adding sodium phosphate or phosphoric acid to prepare lithium phosphate; dissolving the lithium phosphate with ferric sulfate again to obtain the lithium sulfate solution and a compound taking iron phosphate as a principle component, returning the lithium sulfate solution to the system to prepare lithium carbonate, and calcining the iron phosphate slag to remove organic matters and carbon in the slag; and slurrying to prepare cell grade iron phosphate. According to the method for recovering lithium from lithium iron phosphate disclosed by the invention,the lithium is totally converted into the product lithium carbonate in the method, the process flow is short, the cost is low, the lithium recovery rate is 97%, the metal lithium in the lithium iron phosphate can be effectively recovered, and all the slag is converted into the cell grade iron phosphate.

Description

technical field [0001] The invention belongs to the field of recycling of secondary resources and circular economy, and relates to a method for recovering lithium from scrapped lithium iron phosphate slag. Background technique [0002] As people pay more and more attention to issues such as energy and the environment, as well as the depletion of oil resources, the non-polluting characteristics of new energy vehicles have attracted the attention of governments and automobile companies in various countries. Among all kinds of new energy vehicle batteries, lithium iron phosphate batteries have been widely used because of their advantages such as abundant raw material resources, low price, no pollution to the environment, stable structure and good thermal stability. In the process of preparing a large amount of lithium iron phosphate cathode materials, there will inevitably be unqualified products and positive electrode materials to be recycled in waste lithium iron phosphate ba...

AI Technical Summary

Problems solved by technology

This method has a simple process and high lithium recovery rate, but the recovered lithium and iron are not further prepared into high-quality products, so the process needs to be further improved, and the recovered lithium phosphate and iron phosphate can be prepared into new energy sources with a large market battery grade products

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