Determination of Activities in Slags Containing Chromium Oxides.

Abstract

Activities of CrO and CrO1. were determined in slags based on the systems of CaO-SiO.-CrOx, CaO-SiO2-MgO-CrOx,CaO-Si02-Al2O3-CrOx, and CaO-SiO2-MgO-Al203-CrOx with electro-motive force method, Equilibrium wasachieved between Cr-saturated CrAgailoy and slags. Effects of temperature and slag composition on the activities of chromiumoxides and the oxidation state of chromiumin the slags were investigated. Chromiumoxides activities decreased but the divalent chromiumfraction in the slags increased whenelevating temperature in the range of 1500-1 600'C. The slag basicity has a significant effect, the higher the slag basicity, the higher the activities of chromiumoxides, and the lower the divalent chromiumfraction. By partial substituting MgOfor CaO,activities of CrOand CrO1.5 will decrease, but the effect on the oxidation state of chromiumin the slag is not obvious. Increasing Al2O3 content from O to 10mol% results in higher activities of chromium oxides and lower divalent chromium fraction. Further increasing of Al203 content to 20mol% does not cause any significant effect, In addition, activities of chromiumoxides and oxidation state of chromiumin a FeCr type slag system were examined.