Shigeru Nagashima1, Takashi Katsura1
1Department of Chemistry, Faculty of Science, Tokyo Institute of Technology
Tóm tắt
Abstract
The solubility of sulfur in Na2O–SiO2 melts with the Na2O/SiO2 molar ratios of 1/3, 1/2, and 1/1 was investigated by varying the oxygen partial pressure at 1100, 1250, and 1300 °C. The results at 1100 °C are complicated, for the equilibrium state within the gas phase is not established. From the experiments at 1250 and 1300 °C, the following conclusions are reached: (1) When the temperature and the Na2O/SiO2 ratio in the melt are constant, the solubility of sulfur increases with an increase of the total amount of sulfur in the gas phase. (2) When the temperature, the Na2O/SiO2 ratio, and the total amount of sulfur in the gas phase are constant, the solubility of sulfur shows its minimum at a specific oxygen partial pressure; at higher oxygen partial pressures, the sulfur dissolves in the melts mostly as sulfate, while at lower oxygen partial pressures, the sulfur dissolves mostly as sulfide. (3) When the temperature and the total amount of sulfur in the gas phase are constant, the solubility rises greatly with an increase in the Na2O/SiO2 ratio in the melt. (4) When the Na2O/SiO2 ratio in the melt and the total amount of sulfur in the gas phase are constant, the minimum point of the solubility shifts in the direction of higher oxygen partial pressures as the temperature increases. This corresponds to the shifts of the equilibrated gas composition as the temperature increases.
