Method of recovering phosphate radical and sulfate radical from iron phosphate production wastewater

Abstract

The invention provides a method of recovering a phosphate radical and a sulfate radical from iron phosphate production wastewater. The method particularly comprises the steps of: (1) adding Ca(OH)2 into an iron phosphate mother solution for reaction to form first sediment residue and first sediment liquid, (2) adding an ammonia-containing solution into the first sediment liquid for reaction to form second sediment residue and second sediment liquid, (3) mixing the first sediment residue and the second sediment residue to form phosphorus containing gypsum, and adding the phosphorus containing gypsum into the iron phosphate mother solution for reaction to form conversion filtrate and calcium sulfate, (4) allowing the conversion filtrate to flow back to the step (1), stopping adding the ironphosphate mother solution, repeating the steps (1), (2) and (3), and (5) mixing the second sediment liquid and acid liquid to form a neutralization regulating solution, and performing reverse osmosis,evaporation and crystallization on the neutralization regulating solution to form an ammonium sulfate solid and a monoammonium phosphate solid. The method can achieve complete separation and thoroughrecovery of the phosphate radical and the sulfate radical in the wastewater, and a phosphate radical product and a sulfate radical product are higher in purity.

Description

technical field [0001] The invention belongs to the technical field of new energy material preparation, and in particular relates to a method for recovering phosphate and sulfate from ferric phosphate production wastewater. Background technique [0002] Iron phosphate is the main cathode material for lithium-ion batteries, and its preparation process mainly includes co-precipitation method, hydrothermal method, etc. Among them, the co-precipitation method refers to dissolving the iron source and phosphorus source (such as monoammonium phosphate), adding other compounds to precipitate iron phosphate, and then washing, drying, and calcining to obtain iron phosphate products. During the preparation of ferric phosphate by co-precipitation, a high concentration of sulfate (SO 4 2- ), phosphate (PO 4 3- ) and ammonia nitrogen (NH 4 -N) acidic mother liquor. The existing process for treating ammonia nitrogen, phosphorus, sulfur, acid and other pollutants in the ferric phospha...

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Problems solved by technology

The existing process for treating ammonia nitrogen, phosphorus, sulfur, acid and other pollutants in the ferric phosphate mother liquor is not only complicated in process and high in operating cost, but also cannot realize the resource utilization of valuable components in wastewater, which in turn leads to high production costs, Environmental pressure is high

[0003] Chinese patent application CN108975469A proposes a step-by-step method for removing phosphate and sulfate in iron phosphate wastewater. This method recovers most of the phosphate in the wastewater in the form of iron phosphate precipitation, but there are still incomplete recovery of phosphate and phosphoric acid. The purity of iron precipitation is difficult to control and difficult to reuse

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