An Electrochemical Consideration on the Silica Reduction

Abstract

An electrochemical approach to the kinetics of multicomponent reactions occurring at the molten slagmetal interface has been proposed and applied to kinetic study of silica reduction.
1. Polarization curves of several elements dissolved in iron were evaluated from the formation free energy of oxides and available electrochemical data.
2. The limiting current density for the diffusion of SiO₂ in slag was estimated as nearly 150-400 rnA/cm² from the experimental results.
3. The facts that the rate of silica reduction is accelerated with the increase of the slag-graphite interface area was clearly explained using the polarization curves.
4. The rate of silica reduction approaches to the maximum, that is, the limiting current, under the large cathodic polarization which could be realized by the increase of slag-graphite interface area, decrease of oxygen activity or applying the external electric potential.
In this condition, the rate of silicd-(Si⁴⁺) diffusion in slag is the rate-limiting step.
Such an electrochemical approach as proposed here might be much useful for the treatments of the multicomponent reaction kinetics in iron-steelmaking processes.