A detailed analysis of the oxidation of zinc sulfide particles was con
ducted in a thermobalance between 548 and 630 degrees C with different
oxygen concentrations. It was found that, in the presence of external
mass-transfer effects, an oxysulfate intermediate was formed. However
, when the flow rate was chosen such that this effect was eliminated,
no sulfates were formed. Analysis of the controlling regimes indicated
that even the use of small particles (<200 mesh) did not eliminate in
ternal diffusional resistance. Thus, using only the initial rate data,
the surface reaction model (-r=kK(A)[O-2]/1 + K-A[O-2]) with no disso
ciation of oxygen was found to depict the data very well up to 609 deg
rees C. Simple power law models were found to be wholly inadequate to
represent the data.