The mining industry has recently started to establish sustainable carbon emission reduction goals. The major source of carbon emissions in the mining process is the transport/haulage of ore and waste, especially over large horizontal and vertical distances. There are different approaches to reduce the carbon footprint in mining. While diesel fuel is still the main energy source used for conventional excavation and truck haulage, leveraging new technologies such as green hydrogen as a replacement for diesel may be one option. Another option is to partly or fully shift from fuel intensive haulage to conveyor-based technology driven by electricity generated from renewables.
RWE TI is an international mining engineering and consulting firm. Its parent company, the RWE Group, owns and operates three large-scale opencast mines in Germany with a total annual mining capacity of 90 million tonnes of ROM coal plus more than 500 million bank cubic metres of waste material. For more than 60 years now, the enormous amount of material has been moved by shiftable in-pit belt conveyors driven by electricity. The experience gained from operating the largest in-pit belt conveyors in the world (38 000 t/h, total length of 250 km, 7.5 m/s belt speed, 2.8 m belt width) has been successfully transferred to other commodities such as copper and iron ore in the last few decades. Coal-based electricity generation will be phased out in Germany by 2038, and RWE is committed to becoming a leading global provider of renewable energy and innovative engineering services.
The authors of this paper have developed a carbon emission estimation tool for the excavation and material handling process in a classic opencast strip mine. They have used the tool to compare the emissions as well as capital (CAPEX) and operating costs (OPEX) of a conventional Truck/Excavator (TEx) operation as a base case with various conveyor based continuous mining equipment (CME) applications, including bucket wheel excavator (BWE) and in-pit crushing and conveying (IPCC) systems. With respect to the latter technology, the required change in mine planning, the novel technology components and specific equipment productivities are derived from RWE’s long-term operational experience. CAPEX, OPEX and the potential reduction in greenhouse gas (GHG) emissions are calculated for the mine’s life. The results show a significant carbon reduction potential (30–85 per cent) depending on the energy mix used, accompanied by significant savings in OPEX.