State of Sulphur and Sulphur-iron Interaction in Na₂O-SiO₂ Slags

Abstract

From the standpoint of external desulphurization, state of sulphur and sulphur-iron interaction in Na₂O-SiO₂ slags were investigated by optical absorption, electron spin resonance(ESR) and S K_α X-ray emission spectroscopies. An optical absorption was observed near 24 000 cm^-1 in the slags produced in the intermediately (Po₂=10^-5.1 atm.) and strongly(Po₂=10^-6.7 atm.) reducing atmospheres. The absorption was assigned to polysulphide ions consisting of several sulphurs. Fe³⁺-S^2- interaction was suggested from the increase of the intensity of ESR absorption near g=6.0 in the slags produced in the strongly reducing atmosphere. Chemical shift study of S K_α X-rays in the slags indicated that sulphur atoms are in the form of S⁶⁺ ions in oxidizing condition(Po₂=0.21 atm.) and in the mixed state of S⁶⁺ and S⁰ in the reducing conditions. It was concluded from these results that, in Na₂O-SiO₂ slags, polysulphide ions such as S₂^-> are formed as intermediate stage with reducing partial oxygen pressure of atmosphere. Further, it was indicated that Fe³⁺-S^2- interaction begins to occur in the vicinity of Po₂=10^-610^-7 atm.