The effect of a temperature gradient on the phase formation inside a magnesia–chromite refractory in contact with a non-ferrous PbO–SiO2–MgO slag

Furnace relinings represent a major operating cost in pyrometallurgy. External cooling is, therefore, often used to reduce the chemical wear by limiting the slag infiltration depth, reducing the reaction kinetics and lowering the solubility of refractory components into the liquid slag. In this paper a new experimental setup is used to study the reaction between a synthetic PbO–SiO2 based slag and a magnesia–chromite refractory under a temperature gradient. Forsterite (Mg2SiO4) is formed throughout the sample, removing SiO2 from the infiltrated liquid slag. The resulting change in slag composition causes the liquidus temperature and the viscosity of the liquid to decrease partially countering the effect of the applied temperature gradient and resulting in the complete infiltration of the sample. The extent to which external cooling prolongs the lifetime of an industrial furnace thus depends on the slag properties and how they are modified after reaction with the refractory.