Sewage treatment and slag recycling process for production of iron phosphate by sodium method

Abstract

The invention belongs to the technical field of chemical engineering, and particularly discloses a sewage treatment and slag recycling process for producing iron phosphate by a sodium method. The method comprises the steps of adding ferrite and an oxidizing agent into the sodium system ferric phosphate production sewage, and initially adjusting the pH value with alkali liquor to obtain a reaction solution; filtering the reaction liquid to obtain first-stage slag and first-stage mother liquor, adding ferrite and an oxidizing agent into the first-stage mother liquor, then adjusting the pH value of the first-stage mother liquor by using alkali liquor, and filtering to obtain second-stage filter residues and second-stage mother liquor; rinsing, slurrying and aging the first-stage slag to obtain iron phosphate dihydrate, and rinsing, drying and sintering the second-stage slag to obtain nano iron oxide red; and carrying out MVR evaporation or salt pan salt drying on the second-stage mother liquor to obtain high-purity sodium sulfate. According to the method, chemical substances such as phosphorus and iron in the iron phosphate production sewage can be recycled and changed into high-added-value products, so that the sewage treatment cost is reduced, zero discharge of the sewage is realized, resources are saved, and circular economic development of industrial production is realized.

Description

technical field [0001] The invention relates to a sewage treatment and slag recycling process for producing iron phosphate by a sodium method, and belongs to the technical field of chemical industry. Background technique [0002] With the rapid outbreak of 5G backup power supply, energy storage, and electric light vehicle markets, and the background of continuous improvement in cost, safety, and technology, the market demand for lithium iron phosphate batteries has risen, and the production capacity of iron phosphate has also increased. The production of iron phosphate requires the use of phosphorus-containing raw materials, resulting in a large amount of phosphorus in the production sewage. If the phosphorus cannot be treated in a proper way and recycled in a high-value-added way, it will cause waste of resources. At present, calcium-based or iron-based phosphorus removal agents are mostly used in the treatment of phosphorus-containing industrial wastewater at home and abro...

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Problems solved by technology

[0003] Aiming at the above defects or improvement needs of the prior art, the present invention provides a method for graded treatment, precise control of the molar ratio and pH value of ferrous ions and phosphorus in various levels of sewage treatment, and a method for preparing different high value-added products to solve the problem of phosphoric acid The recovery of phosphorus in iron production wastewater and the realization of high value-added recycling of phosphorus-containing slag

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