Abstract
(1) A study was carried out on the reduction equilibrium of chromium between molten pig iron (Fe-C at·-Cr[1%]) and molten slag of blast furnace type (CaO-SiO2-Al2O3-(CrO), at the temperature range of 1350-1500°C and the slag basicity CaO/SiO2 ranging from O·6 to 1·4, under one atomospheric pressure of carbon monoxide.
(2) From the fact that the rate of reduction of chromium from slags to pigiron was relatively rapid, the partial equilibrium concerning chromium seemed to have been obtained between two phases.
(3) The chromium oxides in slags was presumably mainly present in the formof CrO, judging from their coloured blue-black. The apparent partition ratio of chromium %(CrO)/%Cr between pig iron and slags was appreciably decreased as increasing the basicity upto CaO/SiO2≈1, in other words the activity coefficients of (CrO) should be much affected by the slag compositions.
(4) The relation between log %(CrO)/%Cr and 1/T( T:°K) was linear and parallel for each slags, the basicity of which ranged from 0·6 to 1·0.
(5) The Cr-O equilibrium relation in pig iron was introduced utilizing theabove results and some other thermodynamical data, and we emphasized that the favorable conditions to eliminate chromium should be reduced to two main factors of 1) more acidicslags and 2) lower temperatures.
