Аннотация
Kazakhstan has large reserves of barite and borate ores. The former are used in small volumes when drilling oil and gas wells as a component of heavy drilling fluid. As for borate ores, the Indersk borate mine previously operating in the Atyrau region has been stopped, and products are not being shipped. In this paper, we consider the possibility of expanding the scope of application of Kazakh barite and borate ores by remelting them to remove unwanted impurities and impart the necessary physical properties. In this paper, the possibility of using Kazakhstani barite and borate ores by thermodynamic modeling of their phase composition and dynamics of its change in the temperature range 800-3000 K is considered. It has been established that the remelting of barite ore must be carried out at temperatures of at least 2150 K. In this case, it is possible to completely remove sulfate sulfur and, as a result of the interaction of BaSO4 with quartz, transform it into a thermodynamically stable barium orthosilicate Ba2SiO4. The dominant mineral component (55%) in borate ore is gypsum dihydrate CaSO4∙2H2O. The interaction of calcium sulfate of borate ore with the silica of the charge leads to the removal of sulfur into the gas phase in the form of dioxide and the appearance of condensed dicalcium silicate. Complete removal of sulfur from borate ore occurs at a lower temperature (1550 K) than from barite concentrate (2150 K). There is no free B2O3 in borate ore remelted at 1550 K. It is all connected to magnesium borates MgB4O7, Mg3B2O6 and calcium Ca2B2O5. Magnesium borates have a melting point of 1261-1639 K (988-1366°C), calcium borate – 1583 K (1310°C). The main mineral component of colemanite is calcium borate pentahydrate 2CaO∙3B2O3∙5H2O. Heating of colemanite leads to the removal of hydrated moisture at 773 K and the formation of anhydrous calcium borates CaB2O4, Ca2B2O5 and magnesium MgBO4, Mg3B2O6, which have a low melting point. In the temperature range of melt outlet from the furnace 1800-2000 K, it is dominated by Ca2B2O5 and MgBO4. The presence of stable compounds of barium and boron in the remelted materials makes it possible to consider them as a promising material for protection against hard gamma and neutron radiation and as a means for removing arsenic, sulfur, and phosphorus from metals