The chemical diffusivity of oxygen in liquid iron oxide and a calcium ferrite

Measurements have been made of the chemical diffusion coefficient of oxygen in liquid iron oxide at temperatures from 1673 to 1888 K and in a calcium ferrite (Fe/Ca = 2.57) at temperatures from 1573 to 1873 K, A gravimetric m ethod was used to measure the oxygen uptake during the oxidation of the mel ts by oxygen or CO2-CO mixtures. The rate was shown to be controlled by mas s transfer in the liquid melt. The chemical diffusivity of oxygen in liquid iron oxide at oxygen potential between air and oxygen was found to be 4.2 +/- 0.3 X 10(-3) cm(2)/s at 1888 K. That in iron oxide at oxidation state c lose to iron saturation was established to be given by the empirical expres sion log D = -6220/T + 1.12 for temperatures between 1673 and 1773 K. For t he calcium ferrite (Fe/Ca = 2.57) at oxygen potential between air and oxyge n, the diffusivity of oxygen was found to be given by log D = -1760/T - 1.3 1 for temperatures between 1673 and 1873 K.