Carbothermic reduction of boron oxide (II). Process optimisation and thermodynamics

The reduction of boron oxide B2O3 by carbon at the surface of an iron melt has been studied. The variables considered were: (i) temperature, (ii) charge composition, (iii) carbon content of the melt. The extent of the reaction B2O3+[B](Fe)=3/2B(2)O(2) has been calculated from thermodynamic data on the properties of the phases involved, and using values obtained from chemical analysis of the samples and the measured volumes of the gas evolved. It has been shown that in carbon-containing iron melts, increasing the temperature would result in an increase in the amount of the boron yield, provided that the initial carbon content is sufficient to initiate a reducing reaction. Thus, the magnitude and extent of reaction (1) would decrease. As expected, the rate of the reaction was found to increase with increasing temperature.