Henrian activity coefficient of Bi in Cu-Fe mattes and white metal

A transpiration method was used to evaluate the Henrian activity coefficien t of Bi (gamma(Bi)(0)) in Cu-Fe mattes and white metal. Values for the acti vity coefficient of Bi (gamma(Bi)) have been evaluated as a function of the Cu/Fe molar ratio from 1 to infinity as a function of the sulfur deficienc y (defined as SD = X-S - 1/2X(Cu) - X-Fe, where X-i is the mole fraction of the i(th) species) from -0.02 to +0.02 and at temperatures between 1493 an d 1573 K. Analysis of gamma(Bi) as a function of the trace element concentr ation reveals that the activity coefficient is independent of Bi content at weight percents less than 0.3, Dependence of gamma(Bi)(0) on temperature w as found to follow the equation log gamma(Bi)(0) = -2.03 + 4.44 . 10(+3) . 1/T(K). The experimental results show that bismuth is stabilized (i.e. low value of gamma(Bi)(0)) in both high and low sulfur melts and that bismuth volatilit y is a maximum near the Cu2S - FeS pseudo binary. The results also reveal t hat free copper, in sulfur deficient mattes, tends to decrease the volatili ty of bismuth. Failure to account for sulfur loss can lead to a significant error. This manuscript also presents a method whereby sulfur loss during a n experiment can be accounted for in computing activity coefficients.