MECHANOSORPTION OF CO_2 BY SILICATES: MECHANISM, KINETICS AND POSSIBLE APPLICATIONS

摘要

Mechanically induced CO_2 extensive sorption by silicate minerals (labradorite, diopside, okermanite, ghelenite, and wollastonite) has been considered. The silicates mechanically activated in CO_2 atmosphere in a planetary mill AGO-2 have been characterized using XRD and IR spectroscopy. Micro- and nanostructure of material resulting from mechanochemical interaction of diopside with CO_2 were investigated using SEM and TEM. The obtained data suggest that CO_2 penetrates the structurally disordered silicate matrix and "dissolves" in the particles volume with formation of homogeneous carbonate-silicate phase. Equations that reasonably good represent kinetics of CO_2 mechanosorption by the silicates have been proposed. These equations enable to calculate mechanosorption coefficients characterizing the diffusivity of CO_2 into disordered silicate matrix under intensive mechanical impact. Correlations between CO_2 content in mechanically activated silicates and CO_2 solubility in the corresponding melts, as well as between mechanosorption coefficients and CO_2 diffusion coefficients in the melts have been revealed. Possible application of the revealed effect in improving of alkali-activated ferrous-magnesium slag binding materials has been discussed.