Improved hydration resistance of MgO-2CaOSiO2-3CaOSiO2composite refractory using low-grade minerals

Three low-grade mineral raw materials, i.e., natural dolomite, high-silicon magnesite, and forsterite tailings were used to prepare a MgO-2CaOSiO(2)-3CaOSiO(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,beta-2CaOSiO(2), and 3CaOSiO(2)with a bulk density of 3.13 g cm(-3)and apparent porosity of 4.6%, was obtained after being calcined at 1600 degrees C for 3 h. The prepared composite exhibited excellent hydration resistance with a weight increase of only 0.03% at 1600 degrees C. Microstructural analysis revealed that a dense matrix consisting of intergranular calcium-silicate phases, was dispersed by rounded MgO aggregates.