Solvent extraction in southern Africa: An update of some recent hydrometallurgical developments

Abstract

Southern Africa was the site of one of the first large solvent-extraction (SX) plants built, following smaller plants in the North American uranium industry and the Ranchers and Bagdad copper plants in Arizona. The copper Tailings Leach Plant at Nchanga, Zambia, was commissioned in 1973 with a capacity of 2800 m 3/h. This was the largest SX plant in the world for more than a decade and is still operational today. South Africa witnessed the first commercial implementation of SX for the refining of the platinum-group metals. More recently, southern Africa has seen the implementation of SX for other base metals, precious metals, and specialty metals. These include the “world firsts” of primary production of zinc using SX by Skorpion Zinc in Namibia, and the large-scale refining of gold by SX at Harmony Gold, South Africa. Several other flowsheets that use SX technology are currently under commissioning, development, or feasibility study for implementation in this part of the world, including those for cobalt, nickel, vanadium, tantalum, and niobium. A review of SX operations in the African subcontinent is presented, with particular attention paid to advances since the turn of the millennium. Several interesting projects under development are also discussed, along with some innovative concepts in flowsheet chemistry that should soon reach commercial application.