Sourcing of critical elements and industrial minerals from mine waste – The final evolutionary step back to sustainability of humankind?

Abstract

Humanity developed from bipedal hominidae via hunters and collectors to a modern high tech society in about 6 Ma. Survival was ensured by a thorough and sustainable use of the available resources during 5,999,750 years. In the last ~250 years (Anthropocene), humanity left the path of sustainability, due to extensive growth, extensive use of metals and fossil energy resources, destabilizing the global ecosystem to an extent, which endangers now the future of humanity itself.In metal mining, in most cases only a minor percentage of the extracted materials are the valuable target elements (e.g. Fe or Al ores 20–70%, Zn 2–15%, Pb 1–10%, Cu 0.2–6%, REE 0.1–0.5%, Au 0.5–20 g/t). Thus, the vast majority of the extracted material is defined as waste, which is deposited in disposal facilities like tailings impoundments, lakes or the sea and in waste-rock dumps, or is backfilled into open pits or underground mines. These mine wastes are the source of environmental pollution, for example via Acid Mine Drainage formation, and fatal risks like during dam failures. To minimize the risk from mine waste in the future, mine waste has to be eliminated, in order to gain back the social license to operate. This applies for both, fresh mine waste and historical mine waste. Latter can still contain important metal contents (specifically the overlooked critical metals like REE, PGE, and battery metals like Co, Ni, Li, Mn), and have therefore a high potential for successful exploration. Additionally, other georesources as sand and industrial minerals will increase the demand in the future and metal mining can provide an important portion as secondary by-products.An inline separation sequence can separate the material in different mineral groups producing economic valuable mineral concentrates. The major volumes of silicates are non-hazardous and, if separated accurately, they can be used as industrial minerals or for construction material. Key is that reactive minerals like pyrite are separated from the non-reactive mineral assemblage. Also, high-tech applications can be found for these materials as for example quartz for solar cell production and glass industry or micas and pyrite for semi-conductors for solar cells. Pyrite itself is usually seen as the trouble maker producing acid mine drainage (AMD), but it is also a resource for Fe, S, H2SO4, and valuable trace elements like Ni, Co, Cu, Zn, Au, Ag, V. Proven mineral processing techniques exist to separate these mineral groups from each and other and to produce different concentrates.Translated into the butcher business, mining uses today from a 500 kg beef, only the 5 kg of filet (1% in case of copper mining) and the rest of the cow is thrown into the river, with the obvious effect that the cadaver oxidize and decompose and pollute the water. The challenge for the mining industry is today to make from the 495 kg of the cow an economic gain, and ensure the raw material supply for the future, instead of giving a legacy of environmental pollution to the next generations.