The world's by-product and critical metal resources part I: Uncertainties, current reporting practices, implications and grounds for optimism
Graphical abstract
Introduction
There are a wide range of factors that a potential mining company needs to consider and carefully assess during the determination of whether (or not) a particular mineral or metal is economically worth the effort of extracting it from the earth in some manner (e.g. Edwards, 2001). At a basic level, this includes finding a body of material enriched in one or more elements or minerals that are mineable (by open cut, underground or in situ extraction methods), processable into a saleable product (e.g. concentrate or metal), profitable (i.e. markets must demand the product at a price greater than the costs of mining; unless mining for other strategic reasons such as national defence or socio-political goals), and which meet the demands of a range of other potential technical, environmental, financial, governance and social factors. Over time, particularly in the last 50 years, the mining industry has developed considerable technical capacity and experience in such assessments, and the requirements for these are now typically enshrined in codes, instruments or guidelines by law, regulation or good industry practice.
In general terms, mining uses the concepts of ore reserves and mineral resources to assess the potential for exploiting a mineral deposit – and for the major metals and minerals, this is now routine and straightforward thanks to the adoption of formal codes and guidelines. There are, however, issues when it comes to metals which are not normally the target of mining projects. For example, indium (In1) is often associated with zinc (Zn) deposits and typically deports to Zn concentrates, with the indium potentially recoverable at a Zn refinery (if they have an indium recovery circuit; e.g. Werner et al., 2015) – yet to a mine, the value of indium is typically negligible to very small and is (in the main) not recognised in prices paid for Zn concentrates. In this case, indium is often termed a ‘companion metal’, as it occurs with Zn but is not the primary metal of interest to a mining company (e.g. Nassar et al., 2015). Many of the metals increasingly used in modern technology are companion metals, including indium, gallium (Ga), tellurium (Te), germanium (Ge), selenium (Se), cadmium (Cd), cobalt (Co), hafnium (Hf), rhenium (Re), and the rare earth elements (REEs, more commonly referred to as rare earth oxides or REOs), amongst others. Furthermore, current supply or resources of many of the companion metals are concentrated in just a few countries (e.g. indium, REOs and China; Re and Chile), leading to concerns over security of supply to continue to support modern civilian and military technologies – with such metals commonly referred to as ‘critical metals’. In the mining industry, however, there is very little data reported on such companion or critical metals in ore reserves, mineral resources or mine production statistics – leading to false concerns or confusion between current supply and future supply potential.
Here, we provide a background to ore reserve and mineral resource reporting in the mining industry, review different sources of such estimates and methods of compiling national or global assessments, and present resource-reserve data for various deposits that do report critical metal data before finally discussing the implications overall for more robust global estimates of the resources-reserves of critical metals. Rather than adopt a pessimistic outlook, we highlight the many technical grounds for optimism for adequate supply of critical minerals and metals for some decades. The following sections form the theoretical background to a multi-part series of studies examining the global resources of by-product and critical metals. In part II (Werner et al., under review a), we develop a methodology to estimate by-product/critical metal resources which explicitly overcomes the uncertainties identified in this study that is then demonstrated in greater detail for the case of indium in part III (Werner et al., under review b).
Section snippets
Background and rationale
In general, the primary concepts to assess the potential exploitation of a mineral deposit are ore reserves and mineral resources, as outlined in codes or instruments such as Australia's Joint Ore Reserves Committee (JORC) Code (AusIMM et al., 2012), South Africa's Mineral Resource Code (SAMREC; SAMRCWG, 2009), Canada's National Instrument 43-101 (aka NI43-101; OSC, 2011), and the associated CIM2 Code (CIM, 2014), or the
Different sources, different methods
The uncertainties inherent in the assessment of national mineral resources and subsequent government policy on exporting and/or stockpiling of minerals are exemplified by the Australian Government's policy on iron (Fe) ore between 1938 and 1960. The Australian government in 1938 decided to embargo the export of Fe ore for two reasons; firstly, as a strategic decision to prevent the development of known Australian Fe ore deposits by the Japanese for export to Japan in the tense period leading up
Case studies: demonstrating different types of uncertainties
This section focuses on a series of case studies that outline the differing types of uncertainties in resource reporting, building on the information presented above.
Critical metals: assessing global resources-reserves
As highlighted already, one of the prime reasons why many critical metals have poor estimates of global reserves and resources is that they are typically not reported in resources-reserves and mine production by mining companies – with many such metals simply extracted at a smelter or refinery with even less publicly reported data (e.g. indium, Se, Cd, Te, Re, etc). This in turn means that it is unclear whether the concerns over the security of supply of these metals (e.g. Naden, 2012) is
Discussion and implications
It is clear that a lack of reporting of the numerous critical metals has led to a paucity of data relating to the global resources of these metals and beyond. This is not a reflection of exploration success (or lack thereof), but rather the historical and present-day economics of critical metal extraction and processing. The fact that these metals are often not the core business of mining companies means that these companies are not incentivised to report or even examine these commodities which
Conclusions
This paper documents and discusses numerous factors which commonly lead to by-products and critical metals not being reported as a potential commodity in the mining industry, and the implications of this lack of reporting. In particular, the lesser economic value of these metals reduces their chances of being extracted, despite their geological presence and potential strategic or technological value. Under the mineral resource reporting codes commonly employed in the mining industry, there are
Acknowledgements
SMJ acknowledges fruitful discussion with Ahmad Saleem of MMG Ltd. on this topic. This work is supported by the Wealth From Waste Research Collaboration Cluster, a CSIRO-university funded joint collaboration cluster between CSIRO Mineral Resources, CSIRO Manufacturing, University Technology Sydney, Monash University, University of Queensland, Swinburne University and Yale University.
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