Thiosulfate leaching of gold is being proposed as an environmentally friendly alternative to the dominant cyanide-leaching technology. Thiosulfate leaching is, to a large extent, dependent on the availability of materials of construction. There are indications that materials of construction could be a major issue if not addressed; particularly their corrosion resistance. Therefore, understanding the corrosion behaviour of materials of construction, such as stainless steels, in this medium is

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... tical to the future development and acceleration of industrial implementation of this new technology. The debate surrounding the use of cyanide in the mining industry has fuelled considerable investigation into the development of some more environmentally benign alternatives. The thiosulfate process has been widely accepted by researchers around the world as a potential alternative lixiviant for the leaching and recovery of gold. Moreover, sodium thiosulfate is relatively nontoxic and, consequently, from an environmental standpoint, has a definite advantage over cyanide. Comparing reagent unit costs, sodium thiosulfate is far cheaper than sodium cyanide. Thus, with similar or even slightly higher lixiviant consumption, the application of thiosulfate for gold recovery can be economical and compete directly with cyanidation. 'Rust never sleeps!', so says a popular song. In a broad sense, corrosion appears to be the reverse process of extraction. In this process, most metals tend to presume a chemicallycombined state rather than a pure metallic form achieving, in the process, the most energy stable iii form possible. Thus, freshly-extracted metals, as well as finished metallic products, tend to deteriorate when exposed to certain environments. Thiosulfate has been identified as such an environment in mining and other industries, where thiosulfate-dominated processes, such as thiosulfate gold leaching, are strongly believed to highly promote localized corrosion. In this work, the pitting corrosion behaviour of 304- and 316-typ [...]