Dan Smith - By-products from Ores and Mine Waste
Updated: May 31, 2020
A significant number of the metals we use in modern technologies do not occur in concentrations in the Earth’s crust that make them suitable targets for mining. Instead, their production is in association with more abundant or valuable metals, where they occur as trace components in major ore minerals, or as exotic minerals in processing streams. Such by-product metals may be recovered during the processing for the main target metals, or recovered later from wastes and residues.
More efficient use of a resource – by greater recovery of by-products has a number of apparent benefits. It reduces and potentially detoxifies waste, and generates additional income streams. However, these benefits are for the most part likely to be quite small for an operational miner. As trace components of an ore, the mass of waste avoided will be trivial compared to that still headed to tailings dams. The value of the by-products recovered – by virtue of their low abundance and sometimes low unit price – is often small. Whilst this may represent additional revenue, it requires the miner to dedicate resources, and hence becomes less appealing.
Many of the metals that we recover as by-products are considered “critical” – they are essential for one or more technologies, and are subject to a threatened or insufficient supply. The demand for critical metals is driving exploration, with and end-goal of mines that can supply metals as primary products. The true value in enhancing by-product recovery lies in enhancing security of resource supply (diversifying the sources) and in avoiding impacts associated with new, dedicated mines. Although by-product recovery is likely to be a minor component of a mine’s revenue stream, there are developing projects that represent alternative financing routes for exploration and mines – partnerships with vertical integration of critical metal consumers, e.g. solar panel manufacturers. This “green finance” is one way in much responsible reserve management can bear fruit for the mining industry.
Associate Professor in Applied & Environmental Geoscience. Research areas focus on mineralogy and geochemistry of hydrothermal ore deposits, and their role in economic, environmental impacts, and resource supply for green technologies.
Centre for Sustainable Resource Extraction and School of Geography, Geology & the Environment, University of Leicester, UK (Djs40@le.ac.uk)
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