Future generations will likely look back at this time and call it the “white gold rush”. Companies and governments are scrambling to secure lithium production creating a historic run-up in lithium prices and many junior companies are adding “lithium” to their names. Historically, lithium was just another industrial mineral, mostly used in glass and ceramics, with minor usage in batteries. Annual global production was around 20 thousand tonnes per year (ktpa) of lithium carbonate equivalent (LCE) in 2010 (USGS, 2011), but started increasing around five years ago to 410 ktpa of LCE in 2020 and 540 ktpa in 2021 (McKinsey, 2022). Analysts believe global demand will increase by 30% per annum for the foreseeable future and the corresponding pricing has skyrocketed. For example, the battery- grade lithium carbonate EXW China price closed at $41,925 per tonne at year-end [2021], an increase of 485.8% year over year (S&P Global, 2022).
Given the current demand, pricing, and investment, everyone from large mining companies, junior explorers, and even car manufacturers are scouring the globe for sources of lithium for batteries to support energy storage and EV production. Lithium deposits can be broadly grouped into one of three categories: 1) brine or salar deposits, 2) lithium bound in lacustrine clays, or 3) as lithium-bearing minerals in pegmatites and granites. Due to a broader global abundance, many lithium-interested groups are focused on the hard rock pegmatite deposits. These types of pegmatites were often mined historically for tin, tantalum, and niobium and are common by-products produced today from operations like Greenbushes in Western Australia. Within lithium-bearing pegmatites, the common minerals of interest include spodumene, lepidolite, petalite, eucryptite, and amblygonite. Each requires good mineralogical and chemical characterization as there are material implications for grade, processing, and recovery between the various lithium-bearing minerals.
Advantages of lithium pegmatites are that mining is conventional, rather than in situ recovery characteristic of the brines, and processing often does not require expensive extraction as from low-grade clay deposits. Currently, lithium pegmatite operations are primarily open pit, but given the pricing and anticipated demand increases, the expectation is that more underground mines will become economically viable in the coming years. When spodumene is the primary lithium-bearing mineral, processing can be straightforward using well-proven technology. As lower grades and other minerals are considered for production, there are additional processing challenges or increased possibility of deleterious materials with iron and sulfur being among the main elements of concern.
Geologically, not all pegmatites are created equal. Pegmatites are defined as coarse-grained intrusives which are often present as dyke swarms associated with granitic intrusions. Chemistry, mineralogy, and geometry can vary greatly between deposits. Often with lithium pegmatites, there are generations of cross-cutting dykes with varying chemistries on a single property resulting in zones of lithium dilution, barren dykes, complex zonation, and thin dykes that present challenges for mining selectivity. Keys for assessing project viability and reducing resource risks for lithium-pegmatite deposits include focusing on structure (syn- and post-mineralization), multi-directional drilling to understand dyke thickness variations and sinuosity at depth, defining mineralogical zonation within dykes, identifying mineralogical and chemical continuity in both lithium-bearing minerals and potentially deleterious elements, and modeling both lithium-bearing and barren dykes to understand internal and external dilution.
Current global production is nearly all from Australia, Latin America, and China but with the current rush the expectation is that many other countries will join in production. As with any boom times, success will depend on diligent technical evaluation to address the many potential pitfalls of developing a hard rock lithium mine.
