On the Distribution of Chromium at Low-Chromium Concentration

Abstract

There have been few researches on the distribution of chromium between an acidic slag saturated with silica and a liquid of iron alloy with low chromium content.According to F. KÖRBER and D. C. HILTY, chromium oxide in the acidic slag changes its chemical form with the change in the concentration of chromium in the liquid iron alloy. The reaction of chromium or the behavior of chromium phase is, therfore, followed by the change in the chromium concentration in liquid phase.
In our latest report over the concentration range of chromium higher than 3 per cent, it was shown that the chromium oxide in the acidic slag behaved like the chromous ion (CrO).
In the present paper, an iron alloy of low chromium concentration is studied. The results are summarized as follows:
1) When the chromium concentration was less than 3%, the oxidation-reduction reaction between chromium and iron in the two phases was represented as 4 (FeO)+3[Cr]→←(Cr₃O₄) +4 [Fe]
2) The distribution of chromium between two phases and the solubility of oxygen were measured, and from their results the equilibrium constants were determined as follows:
(CrO_1.33)_slag
_??_
[CrO_1.33]_metal_??_[Cr]+1.33[O]
K₁=(CrO_1.33)/[CrO_1.33]
K₂=[Cr]·[O]^1.33/[CrO_1.33]
K=(K₁/K₂)=(CrO_1.33)/[Cr]·[O]^1.33
log K=6679/T-0.724