The viability of using the Witwatersrand gold mine tailings for brickmaking

Abstract

South Africa is a mineral-rich country with metals such as gold, copper, and platinum group metals being exploited to a significant extent in the country’s mining history. Mining generates large volumes of tailings, with consequent disposal and environmental problems. By far the most gold that has been mined in South Africa (98%) has come from the Witwatersrand goldfields (Messner, 1991). The gold mines in this area are situated around an ancient sea (over 2700 million years old) where rivers deposited sediments in the form of sand and gravel that became the conglomerate containing the gold (Messner, 1991). The extensive exploitation of the gold resources has led to numerous mine tailings heaps scattered around the Witwatersrand Basin. As long as mining contributes significantly to the economic development of South Africa, generation of these tailings is inevitable. The major environmental impacts from waste disposal at mine sites can be divided into two categories – the loss of productive land following its conversion to a waste storage area and the introduction of sediment, acidity, and other contaminants into surrounding surface and groundwater (Mining Facts, 2014). The gold mining and processing wastes contain large amounts of sulphide minerals such as pyrite, which generate acid mine drainage (AMD) (Rosner and van Schalkwyk, 2000). South Africa is currently faced with the challenges resulting from AMD and the government and mining companies are under pressure to find viable solutions to this problem. This, coupled with the increasing landfill costs, and stricter implementation and enforcement of environmental legislation, has caused the scientific community to focus on finding innovative methods of utilizing mine tailings. Even though some applications of the generated tailings have been exploited, such as in the building of slimes dams and backfill in underground mines, these uses do not take up more than a fraction of the total amount of tailings in the Witwatersrand region. There is therefore a significant need to developing other long-term, commercially viable uses for mine tailings in order to minimize the disposal costs and the impact on the environment. According to Statistics South Africa (2013), South Africa has a human population of about 52.98 million. This population is growing, and this consequently results in an increasing demand for housing, which places severe stress on the natural resources used for construction materials. Conventional bricks are produced from clay fired in high-temperature kilns or from ordinary Portland cement (OPC) concrete. Clay, the common material used for The viability of using the Witwatersrand gold mine tailings for brickmaking