Method for preparing flaky iron phosphate from acidic waste liquid and calcium phosphate waste residue

Abstract

The invention discloses a method for preparing flaky iron phosphate from acidic waste liquid and calcium phosphate waste residue. The method comprises the following steps of: mixing calcium phosphatewaste residue, acidic waste liquid and an oxalic acid solution, performing heating for reaction, and filtering out precipitate residue, thereby obtaining phosphorus-containing leachate; heating the phosphorus-containing leachate prepared in the S1 to 30-70DEG C, adding an iron raw material solution, performing heating to 80-100DEG C, carrying out reaction for 2-5h to obtain iron phosphate slurry,and carrying out filter pressing on the iron phosphate slurry to obtain flaky iron phosphate dihydrate; and carrying out two-stage heat preservation roasting dehydration on the flaky iron phosphate dihydrate prepared in S2 to obtain anhydrous flaky iron phosphate. According to the scheme, the problems that acidic waste liquid is difficult to treat, the treatment cost is high, calcium phosphate waste residue is difficult to recycle, flaky anhydrous iron phosphate is difficult to prepare and the like are ingeniously solved; meanwhile, oxalate is introduced in the leaching process and can form oxalate precipitate with metal impurity ions like manganese, magnesium and copper brought in by calcium phosphate waste residue or acidic waste liquid, and the purity of the finished iron phosphate product is guaranteed.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a method for preparing sheet-shaped iron phosphate by using acidic waste liquid and calcium phosphate waste residue. Background technique [0002] Lithium batteries made of olivine-structured lithium iron phosphate are widely used in transportation equipment such as electric vehicles and hybrid vehicles due to their advantages such as large discharge capacity, long cycle life, high safety, and environmental friendliness. At present, iron phosphate is generally used as a precursor in the industry, and lithium iron phosphate is prepared by a high-temperature solid-state method. The study found that lithium iron phosphate with a flaky structure can be packed more tightly than other lithium iron phosphate with irregular morphology, which is beneficial to improve the compaction density of lithium iron phosphate cathode materials. Iron phosphate is an important raw material ...

AI Technical Summary

Problems solved by technology

However, in the prior art, the phosphorus resource in the calcium phosphate waste residue has not been effectively recycled

[0004] In addition, chemical plants usually produce a large amount of acid waste liquid in the production process, such as acid waste liquid produced by chemical processes such as iron phosphate production, electroplating production, circuit board etching, and high-purity graphite purification. Chemical companies usually need to use evaporative crystallization and reverse osmosis to treat these acidic waste liquids to remove pollutants such as heavy metal ions in the waste liquid to avoid environmental and water pollution, which greatly increases the production cost of the enterprise

[0005] Therefore, it is necessary to find an effective method to solve the problems of difficult treatment of industrial acidic waste liquid, difficult utilization of phosphorus-containing waste residue, and difficult preparation of flaky anhydrous iron phosphate.

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