Dephosphorization of chromium-containing iron with various oxide-halide fluxes.

Dephosphorization experiments under oxidizing condition were carried out to develop an inexpensive flux for the chromium-containing iron with a large dephosphorizing capacity. Among various halides tried in CaO-halide-Cr2O3 systems, NaF and BaF2 are superior to others in their dephosphorization performance for chromium-containing iron though the fluxes are not inexpensive. From view points of both the dephosphorization ability and the flux cost, CaF2 was selected among halides and BaO was added in order to contrive their compatibility. In the CaO-BaO-CaF2-Cr2O3 system, various composition was tried and the composition was optimized. As the result, 90% of maximum dephosphorization degree was obtained with 100g of flux per kilogram of the metal at 2% C and 15% Cr.Effect of carbon content and chromium content in the metal on dephosphorization was investigated with this CaO-BaO-CaF2-Cr2O3 flux. As the result, it became possible to dephosphorize the iron with wider range of carbon (0.2 to 4% C) and chromium (15 to 22% Cr) contents. It was revealed that coexistence of calcium, barium, and sodium as cation was effective in dephosphorization. Fluorine as an anion was more effective in dephosphorization than chlorine.