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  • UTAS PhD Project - Controlling acid and metalliferous drainage generated by legacy mine wastes in Tasmania using industrial wastes

UTAS PhD Project - Controlling acid and metalliferous drainage generated by legacy mine wastes in Tasmania using industrial wastes

The Mining Sector Innovation Initiative Program (MSIIP) managed by Mineral Resources Tasmania (MRT) funds collaborative work between government, industry, and research institutions. The program aims to host research projects focused on four project areas, one being the investigation of innovative solutions for mine rehabilitation and remediation.

The deleterious environmental impacts of acid and metalliferous drainage (AMD) are a major concern in Tasmania. Historic mine sites across the state continue to produce AMD, generated from the oxidation of improperly stored sulphide-bearing mine wastes. Effective active treatment methods are an ongoing economic burden and generate metalliferous sludges that require further processing and disposal, highlighting the need for an economically and technically viable AMD remediation strategy.

In July 2022, UTAS Centre of Ore Deposit (CODES) student, Annah Moyo, completed a PhD project investigating the viability of using industrial wastes to control AMD generated by legacy mine sites in Tasmania.

The study aimed to investigate the potential use of eight alkaline industrial wastes including: green liquor dregs (GLD), red mud, coal ash, wood bed ash, fly ash, and marine shells (mussel, scallop, and oyster) from various industries in Tasmania and Victoria. Laboratory experiments compared the effectiveness of the industrial wastes placed as covers, layers or blended with mine wastes from six abandoned sites in Tasmania.

The findings of the project demonstrated that all the studied industrial waste products, except for wood ashes, produced sufficient alkalinity to neutralise AMD and reduce the solubility and mobility of metals of concern. This proved most effective when industrial wastes were mixed or layered with mine wastes, rather than used as a cover. The co-disposal of industrial and mine wastes acts as a filtration system, eliminating the production of problematic melliferous sludges associated with active AMD treatment practices. Additionally, the high-water retention and low hydraulic conductivity of the industrial wastes reduced permeability and oxidation of the mine wastes, resulting in decreased AMD generation.

The study concluded that alkaline industrial waste products have the potential to be a long-term, economic, and environmentally sustainable strategy for AMD remediation at abandoned mine sites in Tasmania while simultaneously re-using waste products from other industries.

Annah collecting tailings samples at Spray mine site, and laboratory-based leaching tests.