Abstract
The article presents data on research of processes of obtaining concentrated phosphoric acid from Karatau phosphate rock. The research of purification of wet-process phosphoric acid by the method of liquid extraction with organic solvents is given. The influence of magnesium salts and sulfuric acid as impurities on the distribution factor of phosphoric acid is determined. It is shown that with increasing the initial concentration of phosphoric acid from 5.38 to 25.61% P2O5, the distribution factor at 25°C increases from 0.178 to 0.436 for n-butyl alcohol, from 0.06 to 0.183 for isoamyl alcohol, and from 0.120 to 0.320 for tributyl phosphate. Increasing the temperature from 25 to 60°C had little or no effect on the distribution factor. It was determined that the distribution factors of phosphoric acid depend on the initial concentration of phosphoric acid in the presence of sulfuric acid. It is shown that phosphoric acid is extracted better with n-butanol. Extraction of phosphoric acid with n-butanol on the principle of counterflow with subsequent azeotropic distillation of the solvent allows to obtain relatively pure and highly concentrated (56-63% of P2O5) phosphoric acid. The process of dehydration of phosphoric acid in the presence of sulfuric acid in the mixture was studied.