Method for wet purification of phosphoric acid with phosphate mother liquor back extraction and co-production of industrial grade phosphate

Abstract

The invention discloses a method for reversely extracting and co-production of industrial-grade phosphate by using phosphate mother liquor for wet-method purification phosphoric acid, which is capable of lowering the production cost. The method comprises the following steps of a, adding a defluorination agent, an adsorbent and oxidizing agent in wet-method purification phosphoric acid for defluorination and decolorization; b, extracting phosphoric acid with an extraction agent, adding inorganic acid in the middle of an extraction tower; c, desulfurating and washing; d, reversely extracting with industrial-grade phosphate mother liquor; e, finely tuning slurry; f, feeding the finely tuned phosphate slurry into a crystallizer for crystallizing, then carrying out solid-liquid separation and drying to obtain product industrial-grade phosphate, wherein the slurry obtained from solid-liquid separation is industrial-grade phosphate mother liquor which is subjected to pH value adjustment and returned to step d for use. Reverse extraction is carried out by cooled and crystallized industrial-grade phosphate mother liquor, the reverse extraction effect is good, the step of evaporation is avoided, desulphurization and washing are carried out simultaneously, the procedures are simplified, and the production cost is saved. A new preparation method of the industrial-grade phosphate is provided.

Description

technical field [0001] The invention belongs to the field of phosphorus chemical industry, and in particular relates to a method for back-extracting and co-producing industrial-grade phosphate with phosphate mother liquor for wet purification of phosphoric acid, which can reduce production cost. Background technique [0002] The production of industrial-grade phosphate at home and abroad mostly uses thermal phosphoric acid as raw material, but due to the high cost and high energy consumption of thermal phosphoric acid production, under the current trend of energy saving and emission reduction in the world, wet purification phosphoric acid replaces thermal phosphoric acid It is an inevitable trend; however, the use of purified phosphoric acid in the industry to produce industrial-grade phosphate still requires concentration, desulfurization and decolorization of the produced purified phosphoric acid. [0003] The patents for the production of wet-purified phosphoric acid in m...

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Problems solved by technology

[0002] The production of industrial-grade phosphate at home and abroad mostly uses thermal phosphoric acid as raw material, but due to the high cost and high energy consumption of thermal phosphoric acid production, under the current trend of energy saving and emission reduction in the world, wet purification phosphoric acid replaces thermal phosphoric acid It is an inevitable trend; however, the use of purified phosphoric acid in the industry to produce industrial-grade phosphate still requires concentration, desulfurization and decolorization of the produced purified phosphoric acid.

[0003] The patents for the production of wet-purified phosphoric acid in my country include: "A Method for Extracting and Purifying Wet-process Phosphoric Acid to Produce Industrial-grade Phosphoric Acid" with application number 201010212175.0. The process uses 40-58% P 2 o 5 The wet process phosphoric acid is used as raw material through decolorization, extraction, washing, back extraction, desulfurization, concentration and defluorination, and pure water is used for back extraction. Continued production of phosphate products needs to be concentrated to evaporate the water, which is not conducive to cost; (2) a large phosphoric acid storage tank needs to be established for intermediate storage, which has a risk of leakage, which is not conducive to cost and environmental protection; (3) the purification of the produced Phosphoric acid also needs to be concentrated, desulfurized, etc., the process is long, and the investment in equipment is large, which is not conducive to control

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