Impact of Sphalerite on the Olympic Dam Surface Processing Flowsheet

Olympic Dam is a vertically integrated operation producing cathode copper, uranium oxide concentrate and gold and silver bullion. The site includes an underground mine, concentrator, hydrometallurgical circuit with copper and uranium solvent extraction, smelter, copper electrorefinery and slimes treatment. Owing to the integrated nature of the site, the behaviour of minor and deleterious elements is important. The sulphides in the orebody are predominantly copper- or iron-sulphides, and these have been successfully recovered in the concentrator bulk sulphide flotation circuit. The geometallurgy programme identified localised concentrations of sphalerite in un-mined areas of the orebody, which are being considered for future bulk mining strategies. Initial test work and mine plans indicated grades in concentrate of above 2% zinc. Since zinc has not been part of the ore feed, the behaviour of zinc through the highly integrated processing circuit was not understood. The expected behaviour of sphalerite and zinc through the surface flowsheet, and around the future Flash Smelting and Converting smelter was modelled to inform limits in concentrate and in ore, to allow appropriate limits for zinc to be placed on mine sources, and identify blending options.