This article presents the results of research on the development of chemically resistant polymer–mineral casting composites based on industrial waste. The aim of this work is to develop a technological basis for obtaining effective inorganic fillers and highly filled composites for use in chlorine-containing environments. On the basis of theoretical data, mineral fillers and a polymer binder for filling composites were selected, optimal quantities of input hardeners and an appropriate thermal curing mode were determined, and the influence of the filling degree on the properties of composites was studied. The influence of various factors on the properties of the obtained composites was also studied, and the possibility of using local raw materials to obtain special-purpose composites was investigated. Ash from a thermal power plant (TPP) was used as an acid-resistant filler in composites. Two components were chosen as binders: phenol formaldehyde resin and mineral filler (TPP ash). As the third component, hydrolytically active fillers—anhydrite, phosphogypsum and phosphate slag—were used. The degree of filling has a significant influence on the properties of composites, including the compressive strength, chemical resistance and degree of curing, the values of which were elucidated across a wide range of composite variations based on the degree of filling. The conducted research allowed us to establish the limit of admissible anhydrite content, which should not exceed 15 mas.%. To optimize the chemical resistance and durability of the composites of the investigated substances, the method of mathematical planning was used. According to the results of this study, the optimal compositions of composites, in terms of anhydrite, phosphogypsum and phosphorus slag contents, were selected. At the maximum possible degree of filling, these composites exhibit high target characteristics.

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.