Methodology for a better estimation of the reserves and resources of minor metals exemplified by selenium in different copper deposit types

Abstract

Mineral raw materials have always been of great importance in human history and have been the cause of numerous mili- tary conflicts. In addition, new technologies to mitigate climate change, sustainable energy production and mobility, as well as digitalisation, make particular chemical elements indispensable. Some of these raw materials are not mined from own deposits but are minor constituents of basic raw material deposits such as copper, zinc, aluminium and nickel and can only be produced together with them. Since geological resources and reserves of minor metals are generally not included in classification codes — such as JORC — their reserves or resources are not sufficiently documented. Consequently, no reliable assessment of their criticality is possible. We assume that different types of copper deposits have characteristic Se-concentrations. These values are linked and extrapolated with our own database of copper deposits, which is precisely structured according to the type of deposit, tectonic setting, age of mineralisation, copper grades, reserves and resources and geographic location. The result is a tabular listing of selenium’s geological reserves and resources according to the relevant countries, type of deposit, tectonic setting, regions and geological age. These findings show the average Se-content and size of copper deposits. The calculated resources of around 25 million tonnes of selenium are well over two hundred times higher than previously documented and are available to accommodate increasing demand. The methodology presented is suitable for estimating the reserves and resources of other minor metals such as platinum, cobalt, bismuth, molybdenum and tantalum as they are typical constituents of primary mineralisations.