The kinetics are studied of topochemical reactions of the formation of calcium hydrosilicate in a multicomponent aqueous system consisting of waste products of boric acid production. The waste products include silicon dioxide and calcium sulfate in equal molar fractions, an alkali metal hydroxide in a stoichiometric ratio to the molar content of calcium sulfate and silicon oxide for obtaining hydrosilicate calcium, and the volume of water calculated to obtain a solution of alkali metal sulfate with a concentration below saturation. Data are obtained on the kinetics of the formation of calcium hydrosilicates in different modes of processing (normal conditions with constant stirring; ultrasonic action at a temperature of 20°C; microwave exposure with constant stirring at a temperature of 95°C; and autoclaving at a temperature of 220°C). It is found that the fastest reaction rate is characteristic of microwave treatment, and the largest proportion of reacted alkali metal hydroxide is obtained during autoclave treatment.