Mechanosorption of Co2 by silicates: mechanism, kinetics and possible applications

Mechanically induced CO2 extensive sorption by silicate minerals (labradorite, diopside, okermanite, ghelenite, and wollastonite) has been considered. The silicates mechanically activated in CO2 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 CO2 were investigated using SEM and TEM. The obtained data suggest that CO2 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 CO2 mechanosorption by the silicates have been proposed. These equations enable to calculate mechanosorption coefficients characterizing the diffusivity of CO2 into disordered silicate matrix under intensive mechanical impact. Correlations between CO2 content in mechanically activated silicates and CO2 solubility in the corresponding melts, as well as between mechanosorption coefficients and CO2 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.