Experimental Studies on Sulfur Solubility in Silicate Melts at Near-Atmospheric Pressure

Abstract

Various experimental studies in silicate melts have been performed to understand the dependence of sulfur solubility on melt composition and experimental conditions. These experiments were motivated by glass technologists due to the role swulfur compounds play in fining (Muller-Simon 2011, this volume) and coloring (Falcone et al. 2011, this volume) melts. In particular, the risk of foaming in the glass tank and rejects in the glass production due to discoloration and bubbles demand a systematic approach for sulfur solubility in silicate melts. Also sulfur solubility experiments have been conducted by metallurgists, whose interest is centered on the interaction of metal and slag melts to desulfurize steel products (Lehmann and Nadif 2011, this volume). Besides technical applications, sulfur solubility experiments at atmospheric pressure are of importance to geoscientists in modelling near-surface conditions such as sulfur degassing from volcanoes (Oppenheimer et al. 2011, this volume) and the role of sulfur in the formation of ore deposits (Simon and Ripley 2011, this volume). In order to study the effect of polymerization of the silicate network on sulfur solubility, melt compositions were varied in the experiments across broad limits. It has been shown that the solubility generally increases with increasing network modifier to network former ratio (Baker and Moretti 2011, this volume). This supports the idea that the presence of free volume and cationic charge compensators in the network structure promote incorporation and mobility of anionic sulfur species (Behrens and Stelling 2011, this volume). Sulfur speciation is also responsible for the strong dependence of sulfur solubility on oxygen fugacity as reported by Baker and Moretti (2011, this volume) and Muller-Simon (2011, this volume) for natural and technical melts, respectively. Sulfur was found to be stable in these melts as sulfide S2− under reducing conditions …