The reduction of iron oxides by volatiles in a rotary hearth furnace process: Part I. The role and kinetics of volatile reduction

With iron ore reduction processes using coal-ore pellets or mixtures, it is possible that volatiles can contribute to reduction. By simulating the constituents of the individual reducing species in the volatiles, the rates for H₂ and CO were investigated in the temperature and reduction range of interest; hydrogen is the major reductant and was studied in detail. The kinetics of the reduction by H₂ has been found to be a complex mechanism with, initially, nucleation and growth controlling the rate. There is a catalytic effect by the existing iron nuclei, followed by a mixed control of chemical kinetics and pore diffusion. This results in a topochemical reduction of these iron oxide particles. Up to 1173 K, reduction by H₂ is considerably faster than by carbon in the pellet/mixture or by CO. It was also found that H₂S, which is involved with the volatiles, does not affect the rate at the reduction range of interest.