Process for purifying producing extracting solvent of food grade phosphoric acid by wet method phosphoric acid and extracting process thereof

Abstract

An extracting solvent for preparing the food-class phosphoric acid from wet-process phosphoric acid is prepared from tributoxyethyl phosphate, isopropyl ether and cyclohexanol through proportional mixing. Its extracting process includes such steps as proportionally mixing said extracting solvent with wet-process phosphoric acid, oscillating for layering, taking upper-layer liquid, washing it with less food-class phosphoric acid, layering, taking the water phase, multi-stage extracting to the phosphoric acid, multi-stage back extracting by deionized water.

Description

technical field [0001] The invention belongs to a process for purifying wet-process phosphoric acid into food-grade phosphoric acid by using a solvent extraction method using wet-process phosphoric acid as a raw material, and in particular relates to an extraction solvent and a method for extracting phosphoric acid using the extraction solvent. Background technique [0002] The preparation of food-grade phosphoric acid can be made of hot-process phosphoric acid or wet-process phosphoric acid. The quality of hot-process phosphoric acid is better, but the production energy consumption is high, and the requirements for ore grade are also high. The industry prefers to use wet-process phosphoric acid; and wet-process phosphoric acid Phosphoric acid uses inorganic acid to decompose phosphate rock, which is low in cost but has many impurities. Therefore, in order to achieve the same quality as the thermal method, the wet method phosphoric acid must be purifie...

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Problems solved by technology

[0030] Chinese patent 86106453 discloses an extraction solvent composed of cyclohexanol, cyclohexanone and light oil. This solvent has a good separation effect on calcium and magnesium for wet-process phosphoric acid obtained by acid hydrolysis of hydrochloric acid. The separation effect is not obvious

[0031] Chinese patent 03117850.2 discloses an extraction solvent composed of tributyl phosphate and kerosene, which has a low extraction rate of 61.5% for phosphoric acid.

At the same time, barium sulfate enters raffinate to make fertilizer, which not only reduces the quality of fertilizer, but also loses barium sulfate

Kerosene is an organic mixture mainly of various alkanes and aromatics, which can reduce the viscosity of tributyl phosphate system to a certain extent, but it does not help the extraction effect obviously, and there is no special report

[0032] Due to the reason of the extraction solvent adopted, there are following disadvantages in different degrees in the above background technology: the K value (the selectivity of the solvent to phosphoric acid) and the β value (representing the degree of extraction of impurities) of the solvent are low, the yield of phosphoric acid is low, and it is difficult for pretreatment The concentration of the final crude phosphoric acid is high, and solvent recovery is difficult

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