Thermodynamic analysis of the reactions of diopside phase formation during synthesis of ceramic pigments from granulated blast-furnace slag

Abstract

The purpose of this study is to perform the thermodynamic analysis of the reactions of diopside phase (CaOMgO2SiO2) formation during the synthesis of ceramic pigments based on the granulated blast-furnace slag. Thermodynamic analysis is of great practical importance in studying solid-phase interactions, which are involved in the pigment technology. At the same time, the scope of energy-intensive experimental studies of ceramic pigments is significantly reduced. When performing thermodynamic calculations, we assessed the fundamental possibility and direction of occurrence of chemical reactions by determining the changes in the Gibbs energy. In order to verify the calculation data, the change in the mineralogy of the diopside compositions was evaluated with the use of X-ray phase analysis at different firing temperatures. It was found that the diopside phase in the CaO–MgO–Al2O3–SiO2 system is formed in several stages. The merwinite (3CaOMgO2SiO2) mineral is formed first. Further, merwinite, along with blast-furnace slag minerals, is involved in the diopside formation. The formation of diopside is completed at the temperature of 12000С. The findings of the study will provide a reasonable approach to the choice of compositions of ceramic pigments using complex raw materials, including the wastes of various industries.