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

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.