DISSOLUTION OF MGO IN STAGNANT CAO-FEO-SIO2 SLAGS

The rate of dissolution of pure dense MgO compacts in synthetic, stagnant CaO-FeO-SiO2 acid slags has been studied in the temperature range 1473-1673 K. The results indicate the topochemical formation of a dense magnesiowustite layer at the interface between MgO and the slag phase. The growth of the product layer during the reaction as well as the decrease of the radius of the MgO core in partially reacted samples were measured at various time intervals by microscopic analysis. The concentration profiles of iron and magnesium in the magnesiowustite layer for various slag compositions and temperatures were measured by electron dispersive spectroscopy. The mechanism of MgO dissolution in the slag and the growth of the oxide layer are discussed in relation to the diffusivities of the cations in the solid solution.