Research of the Composition of Phosphogypsum Produced During the Extracting of Phosphoric Acid from Ordinary Phosphorite Powder by the Clinker Method

In this article, processes of washing phosphogypsum with water, that formed during obtaining extractive phosphoric acid, by clinker method, from ordinary phosphorite powder (OPP) that is a raw material of Central Kyzylkum were studied. The phosphogypsum formed by washing a sample of phosphogypsum formed in 103% concentration of sulfuric acid without mixing with water, that obtained in the ratio OPP:H2O=1,0:2,5 was found to contain 2,55% P2O5, 29,90% CaO and 42,45% SO3. The acceptable sizes of washing the same phosphogypsum sample have been determined, mixing in different amounts of hot water. Phosphogypsum obtained in acceptable sizes contains 0,75% P2O5, 30,51% CaO and 43,58% SO3. When washing phosphogypsum samples with water, it saves 2.5 times  the amount of water and causes to reduce the amount of P2O5 in its composition by at least 3 times. The amount of CaSO4 in the received phosphogypsum sample is increased from 79 to 86%. The samples of phosphogypsum formed without mixing with water and mixing with water were analyzed by X-ray phase analysis and their mutual salt contents were compared.