19 – Mining and the Lake Eyre Basin environment 181 Olympic Dam The Olympic Dam (Figs 19.1 and 19.6) copper, uranium, gold and silver project is one of the larger base metal–uranium deposits in the world (Table 19.3), particularly including the potential value of rare earth oxides (Mudd et al. 2013 Weng et al. 2015). Despite considerable environmental and political controversy, production began in August 1988, with a large underground mine, flotation mill, copper smelter and refinery, and a copper and uranium hydrometallurgical plant. There were plans to develop a megapit, substantially increasing capacity (costing ~$25 billion), but the Fukushima nuclear accident, combined with low commodity prices, forced BHP Billiton to investigate more economical methods to expand the project and extract value. Despite the large quantity and economic value of rare earths (Tables 19.1 and 19.3), used in beneficial modern environmental and consumer technologies Fig. 19.6. Olympic Dam, near Roxby Downs in South Australia, is one of the largest copper, uranium, gold and silver projects in the world, and includes an underground mine, ore processing mill, copper smelter, refinery, hydrometallurgical facility and massive above-ground tailings dam (photo, B. Parkhurst). Table 19.3. Olympic Dam cumulative production (1988–2014) and mineral resources (2014). Data updated from Mudd (2009) Mudd (2014). Resources Ore mass (Mt) Metal Grade Metal mass Cumulative production 168.5 Copper 2.27% 3.53 Mt Uranium oxide 0.065% ~74.8 kt Gold ~0.6 g/t 54.2 t Silver ~6 g/t 494.5 t Available resource 9550.0 Copper 0.81% 78.47 Mt Uranium oxide 0.026% 2498 kt Gold 0.29 g/t 2,975 t Silver 1.6 g/t 11 040 t Rare earth oxidesa ~0.55%a ~52.5 Mta Available resource (gold only) 283.0 Gold 0.75 g/t 273 t a Not Joint Ore Reserves Committee (JORC)-compliant and represents an estimate only (see Weng et al. 2015)