Mudd, Assoc. Prof. Gavin1
1Environmental Engineering, School of Engineering, RMIT University, Melbourne, Australia
Australia has had a long history of mining and continues to enjoy a robust and extensive mining industry – albeit with a much greater environmental (and social / cultural) footprint. One of the principal environmental legacies of mining is mine waste: specifically, tailings left over from processing ores and waste rock from the mining stage (especially open cut mines). Poorly managed, mine wastes can lead to the formation of acidic and metalliferous drainage (AMD), catastrophic failures or impact on rehabilitation objectives and post-mining land-use. The world, however, still needs the metals provided by mining – many of which are not the primary target of mines but are often extracted as by-products in smelters or refineries, such as indium, tellurium, selenium, gallium and others. These metals are crucial for the transformation of the world’s energy infrastructure to renewable energy (solar photovoltaic panels, wind turbines) and energy storage batteries as well as the electrification of transport (electric vehicles). Other metals of great need include rare earths, which can be mined on their own or as by-products from a variety of mineral deposit types (e.g. monazite from heavy mineral sands, iron oxide copper-gold). Collectively, these metals are often referred to as ‘critical metals’, due to their fundamental importance to modern technology and the risks that a major supply disruption could have on global development needs. Although there are examples of reprocessing tailings to extract additional metals (principally in the gold sector), this practice still focusses on the primary metals – leaving behind untapped potential to extract critical metals. In order to assess this potential, the first starting point is working out how much tailings Australia has stored and where, assigning mineral deposit types and then adding in geochemical assessments to explore potential critical metals which might be present. Despite the lack of data for critical metals, given they are often substitute elements in primary economic minerals (e.g. indium in sphalerite or stannite), concentration data for primary metals can be combined with statistical models used to estimate critical metals. This research presents the first ever national database of mine tailings around Australia, covering most mines and production since the 1970s (and some historical sites) combined with preliminary findings from geochemical assessments for critical metals in those tailings. The approach is a significant advance on understanding the potential for critical metals from tailings in particular.
Gavin Mudd has been an active researcher on the environmental impacts and sustainability of mining for two decades, providing an independent scholarly voice which is recognised around the world. His work has included building big data sets to assess declining ore grades, increasing mine wastes, mineral resources, mining methods, rehabilitation, sustainability metrics and life cycle assessment – as well as extensive research on the numerous critical metals needed for modern technology. With a strong publication record, his research work remains amongst the most cited in the field. Gavin is an Associate Professor in Environmental Engineering at RMIT University in Melbourne, Australia, and teaches groundwater, ethics and environmental policy, life cycle assessment and sustainability in engineering.