Volatility and Vapor Pressure Measurements of Antimony and Arsenic Components in CaO-SiO2-FeO1.5 Slags at 1,573 K by Transpiration Method.

Abstract

As a fundamental study for treating fused oxides containing antimony and arsenic components relating to metallurgical and recycling processes, volatility, a, and vapor pressure of the oxide species evaporating from the CaO-SiO 2-FeO 1.5 slags with Q (%CaO / (%CaO + %SiO 2)) of 0.37, 0.53 and 1 were determined at 1,573 K in a range of mole fraction, N, of SbO 1.5 , SbO 2.5 and AsO 2.5 in the slag between 0.005 and 0.05 by using the transpi-ration method with a vertical volatilization chamber. It was found that the volatility of the antimony and arsenic components in each slag increases with decreasing Q and suggested that control and adjustment of the slag basicity are very important for eliminating these components from the slag by means of volatilization. The log a versus log N plots represented a nearly straight line with a gradient, which is very close to that predicted by the thermo-dynamic consideration, and it was concluded that Sb 4 O 6 and As 4 O 6 are the predominant gas species evaporating from the slags. Raoultian activity coefficients, g, of SbO 1.5 , SbO 2.5 and AsO 2.5 in the slags, which were derived from the measured volatility, decrease with increasing Q, and g SbO 2.5 and g AsO 2.5 are less than unity for the slags with Q of 0.53 and 1.