KINETICS AND MECHANISM OF DECOMPOSITION OF LOW-QUALITY PHOSPHORITES OF THE ZHANATAS DEPOSIT

Abstract

The production of extractive phosphoric acid (EPA) is one of the largest in the main chemical industry. The main part of the produced phosphoric acid is obtained by dihydrate from 24.5% of phosphorite Р2О5. Depending on the quality of the processed raw materials, an acid containing 22-32% Р2О5 can be obtained. The dihydrate method is one of the most developed in industrial practice. Its improvement is mainly associated with the introduction of new hardware solutions aimed at intensifying the process, optimizing and stabilizing the temperature regime (regime). The modern development of phosphoric acid production can undergo significant technological changes. thermal phosphoric acid as well as extraction phosphoric acid, and for this extraction the phosphoric acid goes through a two-stage purification process. Fertilizer DAP contains diammonium phosphate and monoammonium phosphate, as well as several additives containing primary phosphoric acid. Extraction phosphoric acid differs not only in Р2О5 concentration, but also in the content of impurities. The main additives to the extraction phosphoric acid are sulfuric acid, calcium, magnesium, iron, fluorine, aluminum, silicon, sodium, potassium and dimensional substances. Almost all of them affect the composition and technology of diammonium phosphate. During the ammonization process, some impurities from the extracted phosphoric acid are converted to a water-insoluble form, which affects the rheological properties of the reservoir, solubility and nutrient absorption. The main component of the extraction phosphoric acid is sulfuric acid, which, when neutralized, turns into ammonium sulfate. Ammonium sulfate is a stable azygroscopic salt that can be used as a fertilizer on its own. The presence of ammonium sulfate stabilizes the granulation process; therefore, it is recommended to add sulfuric acid from thermal phosphoric acid to the diammonium phosphate composition.