Critical raw materials have been on the agenda for over a decade. However, demand volumes are relatively small, and they are typically extracted as by-products or at worst discarded as waste. Identification, characterisation and assessment of the full metal deportment of any potential deposit are worthwhile outlays at the beginning of a project. Utilising all the available metals in a deposit is best practice and good economics, and drives us towards achieving the UN Sustainable Development Goal no. 12 ‘Responsible Consumption and Production”. It can also have the added advantage of improving the economic viability of the project, through the identification of potential high value by-products.
Bauxite has long been used as the source material for alumina across the globe, and there are many different bauxite deposit types. In Europe, most of the research on by-product metals has focussed on karst bauxite deposits and the contained rare earth elements (REE) [1,2]. REE content of red muds, the waste product of alumina production from bauxite, typically runs at 1 000 ppm [1]. Approximately 1.4 Mt of red mud from karst bauxite is produced in Europe annually alone [3], with potential contained REE up to 140 000 t. Extraction of the REE is technically challenging, and the balance of the REE must be considered [4], but if developed these could provide a significant contribution to the REE market [1].
Bauxite, both lateritic and karst, is also the source of the minor (and critical) metal gallium (Ga) [3,5,6]. Lateritic bauxite deposits in the West African Craton account for almost 20% of global bauxite production [3], but little or no published data exist for critical metals such as Ga or REE for the region [5]. In order to get the most out of deposits, both for more sustainable development of deposits and for economic benefit, it is key that we understand the overall range of metals and the lithological controls on those metal budgets in these deposit types. Furthermore the development of novel processing technologies will allow us to have a wider range of potential sources for critical metals.
[1] Deady et al., 2016 [2] Barnett et al., 2019 [3] BGS, 2020 [4] Binnemans et al., 2011 [5] Schulte and Foley, 2014 [6] Dittrich et al., 2011
Biography
Eimear Deady is an economic geologist at the British Geological Survey, her primary research is in mineralisation in hydrothermal systems, but she has a great interest in alternative resources of critical metals in particular. She is Chair of the Applied Mineralogy Group of the Mineralogical Society.
Eimear Deady & Kathryn M. Goodenough.
British Geological Survey, The Lyell Centre, Edinburgh, EH14 1AF
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