A method for preparing flake iron phosphate by using acidic waste liquid and calcium phosphate waste residue

Abstract

The invention discloses a method for preparing flaky ferric phosphate by using acidic waste liquid and calcium phosphate waste residue, which comprises the following steps: mixing calcium phosphate waste residue, acidic waste liquid and oxalic acid solution, heating and reacting, and filtering out precipitated residue to obtain Phosphorus leaching solution: heat up the phosphorus-containing leaching solution prepared in step S1 to 30-70°C, add iron raw material solution and raise the temperature to 80-100°C, and react for 2-5 hours to obtain iron phosphate slurry, which is filtered to obtain di Water flaky iron phosphate; the dihydrate flaky iron phosphate prepared in step S2 is dehydrated through two stages of heat preservation and roasting to obtain anhydrous flaky iron phosphate. The scheme of the present invention not only cleverly solves the problems of acidic waste liquid difficult to handle, high processing cost, difficult to reuse calcium phosphate waste residue, and difficult to prepare flake anhydrous ferric phosphate; at the same time, the leaching process introduces oxalate, which can Or the manganese, magnesium, copper and other metal impurity ions brought in by the acid waste liquid form oxalate precipitation, which ensures the purity of the finished ferric phosphate.

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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