Method for removing slag before solvent extraction in process of producing industrial-grade phosphoric acid by wet-process phosphoric acid

Abstract

The invention discloses a method for removing the slag before solvent extraction in the process of producing industrial-grade phosphoric acid by wet-process phosphoric acid. The method comprises the following steps of: procedures of solid-liquid separation and fine filtration, i.e., continuously conveying concentrated phosphoric acid slurry, which needs to be pretreated by desulfurization, defluorination and decolorization before extraction and purification of the phosphoric acid by an organic solvent and has 8-10% solid content, to a centrifugal machine, carrying out solid-liquid separation at a rotating speed of 1800-2500r/min, controlling the solid content in clear solution to be in 1%, and conveying solid slag into the next procedure for retreatment; and conveying the clear solution into fine filtration equipment for fine filtration, enabling the solid content in the clear solution to be less than 0.2%, and conveying refined acid to the organic extraction and purification procedures. The method adopts the two procedures of solid-liquid separation and fine filtration to enable the solid content in the treated acid slurry to be reduced below 0.2%, and be conductive to the obtainment of high-quality and high-added-value phosphoric acid products. The method has the advantages that the process is simple, the working is stable and reliable, solid slag in acid liquor can be effectively treated, simultaneously the purposes of desulfurization, defluorination and decolorization can be achieved, and the favorable conditions are created for extracting and purifying the phosphoric acid by the organic solvent.

Description

technical field [0001] The invention belongs to the technical field of fine phosphorus chemical industry, further belongs to the technical field of wet-process phosphoric acid production, and specifically relates to a method for removing slag before solvent extraction in the wet-process phosphoric acid production process of industrial-grade phosphoric acid. Background technique [0002] The production of fine phosphorus chemical industry has very high requirements on the quality of phosphoric acid. In the past, phosphoric acid prepared by thermal method was generally used. Due to the high cost of this method, the price of thermal phosphoric acid is high, and there is no cost advantage. Concentrated phosphoric acid (P 2 o 5 =30~50%) to take pretreatment of desulfurization, defluorination, decolorization, and removal of acid slag in concentrated phosphoric acid. For the solid-liquid separation of defluorination, desulfurization, decolorization slurry and concentrated phospho...

AI Technical Summary

Problems solved by technology

For the solid-liquid separation of defluorination, desulfurization, decolorization slurry and concentrated phosphoric acid, most of the prior art adopts the method of plate-and-frame filter press or ordinary centrifuge liquid-solid separation, but this method has a large area and automation Low level, high labor intensity and other deficiencies