Measurement of SnO Activity Coefficient in CaO–SiO2–FetO–Al2O3 Slag Saturated with Fe

Abstract

AbstractIt is important to clarify the behavior of elements in the reaction between molten CaO–SiO2–FetO–Al2O3 slag and liquid metal during the remelting of Cu scrap. To estimate the desirable slag composition for retaining Sn in metal, the effects of the slag basicity and the concentrations of FetO and Al2O3 on the SnO activity coefficient were investigated. Molten CaO–SiO2–FetO slag (with optional Al2O3 addition) was reacted with liquid Pb–Sn alloy in a pure Fe crucible at 1573 K for 5 h while blowing the CO–CO2 mixture. From the activity coefficients of Sn, Pb, and Fe oxides in the slag, which were calculated using the PCO/PCO2 ratio during heating and the chemically analyzed compositions of slag and metal, their behaviors in slag/metal reaction were discussed. The order of reducibility was PbO > SnO >> FetO. Finally, it was suggested from the thermodynamic and industrial smelting perspectives that the slag condition favorable to SnO reduction is high basicity, around 50 mass% FetO, and low Al2O3 content. Graphical Abstract