Valorization of Ferronickel Slag into Refractory Materials: Effect of Sintering Temperature

Preparation of refractory materials from ferronickel slag by sintering over a broad temperature range (1200°C to 1500°C) with addition of sintered magnesia was explored. The thermodynamic calculations indicated that the amounts of newly generated high-melting-point forsterite and spinel phases increase with increasing temperature. The experimental analysis demonstrated that elevating the sintering temperature promoted conversion and crystallization of forsterite and spinel phases from the original phase of the slag, with simultaneous reduction of low-melting-point enstatite. There was also rapid growth of spinel grains from about 0.5 μm to 5 μm, which should be controlled by selecting an appropriate temperature. The results showed that, by sintering the slag at 1400°C for 3 h with addition of 20 wt.% sintered magnesia, a high-quality refractory material with refractoriness of 1680°C, bulk density of 2.93 g/cm³, apparent porosity of 1.81%, and compressive strength of 166.62 MPa was obtained.