Calcium carbide powder injection into hot metal. Part 2 - simultaneous desulphurization and deoxidation

Calcium carbide was injected into an induction furnace containing 70 kg of carbon saturated iron. In the second part of the two part paper simultaneous desulphurization and deoxidation were studied by continuously measuring the oxygen activity and frequently sampling for sulphur content. At the start of injection there was a period of slow desulphurization, corresponding to a period of deoxidation. After that, it was found that the apparent first order rate constant for desulphurization increased as the oxygen activity was decreased. A mathematical model was developed to describe diffusion controlled desulphurization and deoxidation at calcium carbide and lime particles. (Lime is always present in commercial calcium carbide.) The model accurately describes the trajectories of sulphur and oxygen during refining. The rates of desulphurization and deoxidation were consistent with 30-50% of the particles contacting the melt. A similar conclusion was reached in Part 1 (this issue) via a heat transfer analysis. Finally, the industrial implications of these findings are discussed.