Mining and metallurgical wastes: a review of recycling and re-use practices

Mining is a complex process involving activities that range from exploration through mine development, mineral beneficiation, metal extraction, smelting, refining, reclamation, and remediation In the process of extracting the metal values, these activities produce significant amounts of wastes, typically consisting of (1) solid wastes in the form of waste rock, dusts, sludges, and slags, (2) liquid wastes in the form of waste water and effluents, and (3) gaseous emissions. In South Africa, mining and metallurgical wastes constitute one of the biggest challenges to the environment. If not managed properly, the anthropogenic effects of these mining and metal extraction activities can result in irreversible damage to the environment and a hazard to humans. In South Africa, in particular, these types of wastes are usually disposed of in landfills, thereby creating serious environmental and health challenges for communities. Mitigating the effects of such mining, metallurgical, and metal manufacturing processes requires a holistic waste management approach that incorporates reduction in the amount of waste produced, in-process recycling, and finding new markets and applications in other sectors of the economy (Lottermoser, 2011; Environmental Protection Agency, 2015; World Steel Association, 2015; Ndlovu, Simate, and Matinde, 2017). As such, increasing the recycling and re-use of the different types of wastes is a potential panacea to the environmental and health challenges posed by these waste streams. Despite the environmental challenges associated with these types of wastes, the mining and metal extraction industries can be integrated to form a circular economy model that promotes zero waste through the re-use and recycling of these waste materials The different waste streams can in fact be considered as secondary sources of valuable metals and other resources.