Reaction Kinetics of Silica Reduction by Aluminium in Liquid Iron

Abstract

Experimental results are given for the rate of reduction of silica after aluminiumaddition to iron melt, which contains about 0.07% silicon and is in equilibrium with silica crucible at 1600°C and 1635°C.
The whole process of reaction after aluminium addition is divided into four periods, in which the following material balances hold,
1st period 2ΔO=4ΔSi+3ΔAl 2nd period 4ΔSi+3ΔAl=0
3rd period 2ΔO=3ΔSi+4ΔAl 4th period ΔO=2ΔSi
and within the 2nd period, silicon and aluminium contents of iron melts change linearly with time and oxygen contents of them are kept constant.
It is shown that the adsorption of oxygen to the crucible-melt interface is the rate-controlling process in the reduction of silica. On the assumption that the reaction proceeds steadily through the 1st and the 2nd periods, the rate constant and the activation energy of oxygen adsorption and changes of the dissolved oxygen contents within the 1st period are obtained.