WASTE MANAGEMENT
Working towards
ZERO WASTE
The mining industry is one of the biggest contributors to waste in South Africa. The industry is mindful of this fact and is continuously working on implementing waste management strategies that will not only manage mine waste, but also reduce the amount of waste produced. By Dineo Phoshoko
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he mining sector is in need of solutions that can shift and boost it to regain its competitiveness and become a key contributor and driver of economic recovery in the wake of the pandemic. Appropriately managing and minimising waste is among the industry’s key interventions. Dave Morrey, general manager, EnviroServ, explains that there are three main categories of mine waste in volume. First, there is overburden, which is waste that consists of soil and rock that needs to be removed in order to get to the ore deposit. The second category of waste is tailings, which is waste that remains following the extraction of valuable product from the ore. Tailings dams are also included in this category. Such dams are used to store waste produced during the process of extracting the valuable product from the ore. The third category of waste is slag, which is what remains following smelting or refining processes in mining. The three categories of waste above are generally managed within the mine itself. There are other types of waste, though, such as hazardous waste from maintenance and processing activities, laboratories, spillages, waste tyres, food waste and general waste. In addition, Morrey adds that contaminated rubble resulting from contaminated demolished or refurbished plants also counts as waste.
Dealing with mine waste Different waste types are dealt with differently. Hydrocarbon waste contains elements of oil, diesel or petrol. This often occurs as a result of spillages or leaks – which can happen anywhere on the mine site. A bioremediating method is used to dispose of hydrocarbon waste. The approach entails using soil
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isolation products to treat the spillage area. Such products contain microorganisms that break up the carbon in the affected spillage area, leaving it free of hydrocarbon contamination. Sawdust and other flammable materials were traditionally used to clean up highly combustible hydrocarbons. This is not only ineffective but also potentially hazardous. Some mines and municipal by-laws prohibit their use. Leading adhesives, electrical terminations and mineral products producer Pratley supplies solutions that are effective, non-flammable and eco-friendly. If the waste cannot be disposed of through bioremediation, it is transported to a compliant hazardous treatment facility. It is not uncommon for samples of waste in this category to be tested at a laboratory to identify the extent to which the waste is contaminated with hazardous chemicals. Another method of identifying the extent of hazardous chemicals present in waste is through a local soil analysis. It is important to be mindful of the quantity of hazardous chemicals that are present in waste to ensure that they are within the threshold limits and adhere to the regulations and permit requirements at the point of treatment or disposal. Old tyres from mine dump trucks also contribute significantly to waste production. Albi Modise, chief director: Communications at the Department of Environment, Forestry and Fisheries (DEFF), explains that the process of disposing of waste tyres involves their collection from mainly fitment centres and mines (where tyre waste is generated), temporarily storing the tyres at waste tyre storage and pre-processing facilities, and recycling and/or recovering energy at various tyre processing facilities, which include cement kilns, crumbing facilities and pyrolysis plants, among others. “The processing facilities are supplied with whole tyres and/or pre-processed tyres (i.e. shred or cut tyres),”
