Abstract
The article describes the process of obtaining extraction of phosphoric acid from phosphate-siliceous phosphorite shales of the Zhanatas deposit, by the sulfuric acid extraction method of obtaining EPA for use in the production of diammonium phosphate. Extraction decomposition of phosphorite by sulfuric acid proceeds with the formation of phosphogypsum and with fluorine released into the gas phase in the form of HF and SiF4 and processed into H2SiF6. The studies were carried out using circulating solutions of EPA with a concentration of 3.80-18.91% P2O5, phosphorite with a content of, (wt. %) P2O5 - 18.14; MgO - 13.43; Al2O3 -1.01; CaO - 25.1; F - 0.58; CO2 - 19.55, etc., sulfuric acid concentration of 92.5% was diluted to 50%. The norm of sulfuric acid is 100% of stoichiometry for CaO and MgO. The impurities Fe2O3 and Al2O3 present in phosphorite by 82-91% are extracted into the phosphogypsum precipitate in the form of medium phosphates. Fluorine introduced with phosphate raw materials into the extraction stage passes into the production acid by 60-70%, 10-20% – into phosphogypsum, and in a small amount 8-12% is released into the gas phase. The resulting EPA product can be used in the production of diammonium phosphate