2.1.3. Kinetics of hydrochloric acid decomposition of calcined concentrate of boron raw materials from the Ak-Arkhar Deposit

Experimental data of the dependence of hydrochloric acid decomposition on extraction of boron oxide, studied at temperatures of 20-80 deg C and the duration of the process from 15 to 60 min, with increasing temperature, the extraction of boron oxide from the composition of borosilicate raw materials increases significantly. In the studied temperature range the degree of boron oxide extraction increases from 24.1 to 86.8 %. The rate constants of boron raw material decomposition were calculated by the first order kinetic equation. The plots of the dependence of lg 1/(1-α)·10 on time satisfactorily fit on a straight line having a negative slope. Variation of the rate constant of decomposition of borosilicate raw materials of Ak-Arkhar deposit by hydrochloric acid from the process temperature obeys the Arrhenius law, which is confirmed by the straight-line dependence of lg K on 1/T·10³. The points satisfactorily fit on the straight Arrhenius line, according to the slope of which the value of apparent activation energy at hydrochloric acid decomposition of boron raw materials of Ak-Arkhar deposit, equal to 29.44 kJ/mol, was calculated. Numerical values of activation energy and rate dependence at hydrochloric acid decomposition of raw materials testify to its occurrence in the diffusion region.