Determination of Activities in Slags Containing Chromium Oxides.

Activitiesof CrO and CrO1.were determined in slags based on the systems of CaO-SiO.-CrO*,CaO-SiO,-MgO-CrO*.CaO-Si02-Al.O,-CrO*, and CaO-SiO*-MgO-Al=0,-CrO*with electro-motive force method, Equilibrium was achieved between Cr-saturated CrAg ailoy and slags.Effects of temperature and slag composition on the activities of chromiumoxides and the oxidation state of chromium in the slags were investigated.Chromiumoxides activities decreased but the divalent chromiumfraction in the slags increased when elevating temperature in the range of 1 500-1 600'C.The slag basicity has a significant effect, the higher the slag basicity, the higher the activities of chromiumoxides, and the lower the divalent chromium fraction.By partial substituting MgO for CaO,activities of CrOand CrO, = will decrease, but the effect on the oxidation state of chromium in the slag is not obvious.Increasing Al.O, content from O to 10mol"/.results in higher activities of chromium oxides and lower divalent chromium fraction.Further increasing of Al.03 content to 20mol"/.does not cause any significant effect, In addition, activities of chromiumoxides and oxidation state of chromium in a FeCr type slag system were examined.