Raman Spectroscopic Analysis of Electrochemically Oxidized Pyrite and Galena

Iron pyrite is a common constituent of coal and its presence during combustion leads to the production of sulfur dioxide and acid rain. Consequently, there is a large research effort dedicated to improving the methods of separating pyrite from coal. One method of separation is to utilize the natural hydrophobicity of many sulfide ores. It has been observed that under the correct conditions of pH and electropotential that sulfide minerals are sufficiently hydrophobic that they can be readily floated. This has been attributed this to the formation of elemental sulfur on the surface of the sulfide minerals [1]. Therefore, there is an interest in identifying the conditions that give rise to sulfur formation on the pyrite surface. In this study Raman spectroscopy is used to evaluate the pyrite surface in situ for various applied potentials. As a source of comparison, the surface products of galena (PbS) and electrodeposited sulfur on platinum are also given.