1990 Volume 31 Issue 9 Pages 793-801
To clarify the effects of oxygen potential, temperature and slag composition on the solubility of tin in slag, liquid tin or tin-iron alloy was brought into equilibrium with various slags of the FeOx–CaO–SiO2 system mostly at 1573 K. The experiments were carried out by measuring oxygen potentials by use of oxygen concentration cells. Increasing oxygen potential resulted in increasing tin content in slag and decreasing iron content in metal. Tin in slag was estimated as being divalent. And the contents of tin were generally similar for both binary fayalite (FeOx–SiO2) and ferrite (FeOx–CaO) type slags, and much higher than those in ternary FeOx–CaO–SiO2 slag. The minimum solubility of tin in slag may be observed at the molar ratio of CaO/SiO2 which is near 2 if the slag is in the molten state. Increasing iron oxide content results in increasing tin content in slag. The activity coefficient of SnO(l) in binary fayalite (FeOx–SiO2) or ferrite (FeOx–CaO) slag is 1 to 2 and the maximum activity coefficient is around 7 in the ternary FeOx–CaO–SiO2 slag whose composition is close to saturation with solid dicalcium silicate and 25 mass% iron oxide. For practical purposes, tin content in slag is shown as a function of iron content in metal to know how much tin from slag can be reduced with desirable metal composition. Based upon the experimental results, the tin smelting process was reasonably explained.
