Mineralogical Composition of Kyzylkum Washed Dry Concentrate and Its Processing into Simple Superphosphate

摘要

The various types of phosphate minerals of the apatite group have been analyzed. The phosphate substance of phosphorites except fluorapatite, can be represented by fluorocarbon apatite-francolite or kurskite. The highest phosphorus content is found in fluorapatite, and the lowest in kurskite. In terms of the unit cell parameters (a(0) = 9.33 angstrom), the phosphate mineral of granular phosphorites of the Kyzylkum desert is francolite. The mineralogical composition of the washed dried concentrate, a granular type of phosphorites of the Central Kyzyl Kum, was studied by X-ray and chemical methods of research. It has been established that the main phosphate mineral of granular phosphorites of the Kyzyl Kum is francolite. Calcite, dolomite, gypsum, quartz, calcium silicate, etc. are present as gangue. The rate of sulfuric acid for the decomposition of washed dried concentrate (25.75 P2O5) in terms of obtaining simple superphosphate (at least 17 P2O5) has been calculated. A distinctive feature of the proposed in-line method over the classical one (chamber) is that the entire production cycle of natural phosphate processing is carried out in two stages. At the first stage, the phosphate raw material is treated with a stoichiometric consumption of concentrated sulfuric acid (at least 93), under conditions of complete decomposition of the washed dried concentrate with the formation of phosphoric acid and anhydrite crystals (calcium sulfate). The reaction temperature is 130 degrees C. At the second stage, the resulting concentrated solution of phosphoric acid in a mixture with sulfuric acid participates in the reaction with an additional introduced amount of washed dried concentrate, which is the basis of the mechanism of chemical formation of monocalcium phosphate and granulation of superphosphate mass. On comparison to the conventional flowsheet, the process excludes the stages of warehouse maturation, ammonization and drying of the product.