Improved hydration resistance of MgO–2CaO·SiO2–3CaO·SiO2 composite refractory using low-grade minerals

Abstract

Three low-grade mineral raw materials, i.e., natural dolomite, high-silicon magnesite, and forsterite tailings were used to prepare a MgO–2CaO·SiO _2 –3CaO·SiO _2 composite refractory, and its hydration resistance was essentially improved. Free CaO was converted into more stable calcium silicate which protected MgO from hydration, and low melting phases formed by impurities promoted densification. The composite refractory, predominantly composed of MgO, β -2CaO·SiO _2 , and 3CaO·SiO _2 with a bulk density of 3.13 g cm ^−3 and apparent porosity of 4.6%, was obtained after being calcined at 1600 °C for 3 h. The prepared composite exhibited excellent hydration resistance with a weight increase of only 0.03% at 1600 °C. Microstructural analysis revealed that a dense matrix consisting of intergranular calcium–silicate phases, was dispersed by rounded MgO aggregates.

Keywords

• low-grade minerals
• calcium-silicate
• composite refractories
• hydration resistance