Jm. Coudure et Ga. Irons, THE EFFECT OF CALCIUM CARBIDE PARTICLE-SIZE DISTRIBUTION ON THE KINETICS OF HOT METAL DESULFURIZATION, ISIJ international, 34(2), 1994, pp. 155-163
The effects of particle size distribution on the kinetics of hot metal
desulphurization were investigated by pilot-scale injection. Three di
fferent particle size distributions of calcium carbide were injected i
nto 70 kg heats of carbon-saturated iron. The sulphur contents and oxy
gen activities were measured during the injection. The reaction in the
plume during the injection could be described as a first-order, diffu
sion-controlled reaction, after an incubation period lasting between 2
0 and 40 sec. This rate constant was found to increase as the particle
size decreased. A kinetic analysis based on mass transfer theory was
performed considering the total particle size distribution of the calc
ium carbide. Through this analysis a new average size, directly relate
d to the mass transfer behaviour, was developed. Comparison of the obs
erved and theoretical dependencies of the first-order rate constant on
the powder feed rate suggests that the fraction of particles in conta
ct with the melt decreases as the particle size decreases. Finally, is
sues of scale-up and economic assessment are discussed.