Synthesis and Sintering Reaction Mechanism of High-Performance MgO-CaO-Fe2O3 Clinker

Abstract

High-performance MgO-CaO-Fe2O3 clinker was prepared using magnesite from Xinjiang (with high calcium and low silica), calcium oxide, and ferric oxide as raw materials. Microstructural analysis and thermogravimetric analysis, combined with HSC chemistry 6 software simulations, were used to investigate the synthesis mechanism of MgO-CaO-Fe2O3 clinker and the effect of firing temperature on the properties of MgO-CaO-Fe2O3 clinker. The results show that MgO-CaO-Fe2O3 clinker with a bulk density of 3.42 g·cm-3, water absorption of 0.7%, and excellent physical properties can be formed by firing at 1600 °C for 3 h. In addition, the crushed and reformed specimens can be refired at temperatures of 1300 °C and 1600 °C to achieve compressive strengths of 17.9 MPa and 39.1 MPa, respectively. The main crystalline phase of the MgO-CaO-Fe2O3 clinker is the MgO phase; the 2CaO·Fe2O3 phase generated by the reaction is distributed between the MgO grains to form a cemented structure with a small quantity of 3CaO·SiO2 and 4CaO·Al2O3·Fe2O3 also distributed between the MgO grains. A series of decomposition and resynthesis chemical reactions occurred during the firing of the MgO-CaO-Fe2O3 clinker, and the liquid phase appeared in the system once the firing temperature exceeded 1250 °C. The presence of the liquid phase promoted intergranular mass transfer between the MgO grains, ensuring the continuous growth of the MgO grains and furthering the densification of the MgO-CaO-Fe2O3 clinker.