Physicochemical properties of iron oxides opportunities for useful AMD products

Acid mine drainage (AMD) is formed by biotic and abiotic processes, characterised by high sulphate and heavy metal concentrations, and is difficult to treat due to the the complex iron/ferric oxidation chemistry. Advances in detecting iron oxides (including oxyhydroxides) at the nanoscale indicate that the size and shape of an iron oxide phase influences the stability and metals in environment. Precipitation, dissolution and reprecipitation of various iron oxides phases with exchanged or adsorbed metals, depend on factors such as pH/redox, temperature and biological activity. For this reason, the presence of iron oxides and associated biofilms may serve as water quality indicators of the type of environment in which found. Understanding the pigmentation, adsorption and catalytic properties of the various iron oxides in situ will contribute to the gaps in knowledge of iron cycling, but also serve to as improve AMD management by better control/valorisation of AMD products6. This project aims to develop a suite of lower cost techniques to that may identify and characterise ferruginous material for improved management or valorisation strategies. The selected site for study is the Mount Lyell region which have has produced over 1.3 million tonnes of copper, 750 tonnes of silver and 45 tonnes of gold since mining commenced in the early 1890’s. Environmental controls were non-existent for the majority of the period of mining and processing operations and consequently there is a legacy of environmental degradation. The Eluting from the site are site and offers various types of iron oxide phases, including precipitates from active treatment and legacy (untreated) material. The materials will have various metals or organic material associated to the iron oxide structures and will be analysed in conjunction with associated water quality parameters. The The findings are will expected to identify conditions that produce either a more reactive or a stable iron oxide product with useful pigment or catalytic properties. Ultimately understanding the natural iron oxide chemistry may lead to better management or recovery/valorisation resources to off set AMD treatment costs.