Mechanochemical interaction of alkali metal metasilicates with carbon dioxide: 2. The influence of thermal treatment on the properties of activated samples

摘要

Processes proceeding during the heating of the samples of lithium, sodium, and potassium metasilicates mechanochemically activated in carbon dioxide are studied using thermal analysis, X-ray phase analysis, and IR spectroscopy. Upon the heating of the samples of sodium and potassium metasilicates, the reversal of phases occurs in the sequence according to their appearance during the mechanical treatment in the mill in the atmosphere of carbon dioxide. Hydrocarbonates are first decomposed to neutral carbonates followed by their interaction with silica to form metasilicates. In the course of thermal treatment of lithium sample, the metastable carbonate-silicate phase, which is formed due to the intense mechanosorption of carbon dioxide, is decomposed first. Afterwards, lithium carbonate formed at the final stage of mechanoactivation reacts with SiO2.