The isothermal reduction of chromite ore fines by carbon dissolved in
a high carbon ferrochromium melt in the temperature range 1580-1640 de
grees C has been investigated. The results obtained show a dependence
of the extent of chromite reduction on slag basicity and concentration
of chromite ore in the slag. An overall increase in chromium metal co
ntent of almost 1% was realised. Profiles of chromium oxide distributi
on in the slag between the tri-and divalent states showed that chromiu
m was essentially in the divalent state, Rate constants for the reduct
ion processes Cr2O3 --> CrO and CrO --> Cr at 1640 degrees C, for exam
ple, were found to be 6.6 x 10(-4) s(-1) and 3.68 x 10(-4) s(-1), resp
ectively. An activation energy of similar to 260 kJ mol(-1) for the re
duction of Cr2O3 --> CrO was determined. The magnitude of this activat
ion energy implies that the rate controlling step for this process is
mass transfer of Cr2O3 from the slag to the slag/metal interface, as a
ctivation energies for metal phase control are typically below 70 kJ m
ol(-1). (C) 1997 The Institute of Materials.