Development of an ion chromatographic system suitable for monitoring the gold cyanidation process

This thesis reports the development of new ion chromatographic (IC) methodology suitable for monitoring the gold cyanidation process. This project continues a series of related investigations involving the development of IC techniques, based mainly on reversed-phase ion interaction chromatography (RPIIC), for the speciation of metallo-cyanide complexes formed during the cyanidation of auriferous ores [1-4]. The focus of this earlier work was concerned with the development of suitable methodology for the analysis of the products of the cyanidation process, such as those found in tailings dams and environmental samples. In contrast to the previous investigations, this project has focused on the determination of the various cyano species found during the extraction stage of the gold cyanidation process. These cyano species include uncomplexed ('free') cyanide, metallo-cyanide complexes, thiocyanate and cyanate. It should be noted that the terms 'free' and uncomplexed cyanide are not strictly interchangeable, especially in the presence of labile metallo-cyanide complexes. The change in emphasis from environmental monitoring to process control was originally suggested by Metana Minerals, as a means to improve the efficiency of their cyanide leaching operations. It should be emphasised that cyanide (usually added as sodium or calcium cyanide) is the most expensive reagent used during the extraction of gold from ore.