Implementation of industrial waste ferrochrome slag in conventional and low cement castables: Effect of microsilica addition

Ferrochrome slag is a waste material obtained from the manufacturing of high carbon ferrochromium alloy. This slag is formed as a liquid at 1700 °C and its main components are SiO2, Al2O3 and MgO. Additionally it consists of chrome, ferrous/ferric oxides and CaO. Present work outlines a novel approach in formulating castables with this industrial waste.Samples with decreasing cement content 15–05 wt.% were formulated in combination of both slag and calcined bauxite as matrix components. Effects of varying 0–10 wt.% microsilica as a micro-fine additive in these castables were investigated in this work. Pore filling properties of microsilica improved apparent porosity and bulk density. Phase analysis through X-ray diffraction techniques demonstrates successful formation of spinel and mullite crystalline phases. Mechanical behavior was evaluated through cold crushing strength and residual cold crushing strength after five consecutive water quenching cycles. Scanning electron microscopy measurements were carried out in order to better understand the packing density and reaction mechanisms of fired castables. Slag containing castables portrays good thermal properties such as thermal shock resistance, permanent linear change and pyrometric cone equivalent.