Influence of Various Parameters on the Defluorination of Wet-Process Phosphoric Acid

Abstract

One of the important sources of raw materials for the production of mineral fertilizers in wet-process phosphoric acid (WPA). It is known that WPA is obtained by treating natural raw materials directly with sulfuric acid. Since WPA is used in the production of mineral fertilizers, it is necessary to solve environmental problems with the rational and comprehensive use of mineral raw materials. This is because, during the extraction of natural raw materials, all impurities contained in phosphate raw materials are transferred to the composition of WPA. Therefore, the main goal is to clean the WPA from impurities. This article discusses the purification of WPA from the fluoride deposition method with the use of inorganic reagents. As the inorganic reagent for defluorination WPA used sodium salt. The influence of temperature, time and norm of sodium salt on the deposition method is studied. As a result, the optimal parameters of the purification of WPA by precipitation were determined: the norm of sodium salt -140% of stoichiometry; temperature -40-50 0 C; time -30 min. Under these conditions, the degree of purification of WPA from fluorine is 84%. The size of the crystals formed during the deposition of sodium silicofluoride is 40-50 microns. Composition of the purified WPA under these conditions (wt. %): P2O5 -19; F -0.24.