Degassing of coal particles injected into iron melts

Abstract

A mathematical model was developed, that describes heating and degassing of coal particles blown into liquid iron. The model combines heat transfer from iron melt to particle surface and heat conduction within particle with the kinetics of the degassing process. The endothermic degassing reaction generates heat sinks within the particle. Local heat consumption per time for degassing is determined simultaneously by heat transfer and by the temperature dependent rate constant of the first order degassing reaction. Model calculations result in temperature distribution within particle, degassing rate, and overall degassing time. Overall degassing time, defined by a degassing rate of 99%, is given by tg[s] = fdp1.5 [mm] for 0.05 ≦ dp ≦ 0.8 mm. The factor f lies between 1.02 and 1.14 for various coals. The exponent 1.5 is nearly independent of coal type. Results obtained are in good agreement with published comparable results for rapid degassing of coal particles.