Physico-chemical features of purification of natural and technogenic brine in the production of soda ash

Industrial production of soda in Russia is implemented by the ammonia method according to the Solvay method. The annual output of commercial sodium bicarbonate reaches 2 million tons. The main key stage of soda production is brine purification. The article considers the problems and highlights the areas of research. Experimental techniques are presented. The aim of the work was to consider the physicochemical characteristics and processes of purification of chloride brines of technogenic and natural origin. The following methods were used to solve the set problems: the chemical composition of the initial samples and solutions (brines) was analyzed by the Kapel-205 capillary electrophoresis system; the mineral composition of the water-insoluble residue was studied using a Clever C-31 X-ray fluorescence spectrometer and X-ray quantitative phase analysis on a РоwDiХ 600 Adwin diffractometer. Based on the results of the experiments, the following data were obtained characterizing the physicochemical effect of СаSО4 on the purification of technogenic and natural chloride brines. The soda-caustic method of purifying raw brine is most effectively carried out at a temperature below 12ºC, since at this temperature the residual content of calcium and magnesium ions in the brine is the lowest. Technogenic brines (formation waters) containing a large amount of sodium chloride can serve as a valuable raw material for the production of soda ash. The mechanism of solid phase formation is represented by the formation and growth of amorphous nuclei due to growth along crystallization faces. The second phase is particle coagulation with the formation of large loose aggregates. Further studies will be continued on the study of the mutual solubility of the СаСО3-Mg(OH)2-NaCl system.