Where Lithium Comes from Does Make A Difference? Brine vs. Hard Rock.
As with most things in life there are usually more than one way to do something. The same holds true when it comes to sourcing lithium. There are two primary processes, lithium from brine, or lithium from hard rock, which is our approach at Piedmont. Let’s take a look at both approaches.
Brine: As described by the United States Geological Survey (USGS), lithium brine deposits are accumulations of saline groundwater that are enriched in dissolved lithium. Although abundant in nature, only select regions in the world contain brines, mainly in closed basins in arid regions where lithium salts can be extracted. Brine is pumped to the surface to be evaporated in a succession of ponds, each transfer to a new pond achieves a higher purity until further processed in a chemical plant with the final product from these chemical plants being lithium carbonate. South American countries Chile and Argentina are where the majority of the lithium produced from brines originates, as well as Nevada, to a much smaller extent.
Clay: Theoretically, Lithium can also be extracted from lithium clays, but the commercial scale production of lithium from clays is yet to be realized.
Hard Rock: Around since the bronze age, miners over time have optimized their hard rock operations to achieve not only extremely efficient production, but also sustainable practices. Lithium found in ‘hard rock’ are a part of minerals hosted in Pegmatites. Pegmatites are intruding rock units which form when mineral-rich magma intrudes from magma chambers into the crust. As the last of this magma cools, water and other minerals become concentrated. These metal-enriched fluids catalyze rapid growth of the large crystals that distinguish pegmatites from other rocks. Pegmatites form thick seams called dikes that intrude into other rocks and can measure anywhere from a few centimeters to hundreds of meters. Within Pegmatites is a lithium-bearing mineral known as Spodumene. Lithium from pegmatites can be used to create lithium carbonate or lithium hydroxide, the latter of which is becoming more desirable by battery producers. Historically, Australia has been the leading producer of spodumene.
Battery technology, which is forecasted to be the main ‘driver’ of future lithium demand due to the anticipated rise electric vehicles, is evolving and becoming more advanced over time. Something that is a primary focus is ‘energy density’, which ultimately means how much energy can be stored within certain dimensions. Battery producers such as Tesla are over time adjusting the ratios of the numerous metals used to produce each cathode component within batteries, including nickel, cobalt, manganese, graphite and of course, lithium.
Industry-wide, there is a push toward cathodes with higher nickel content, namely NCM 811 cathodes, which include eight parts nickel, one part cobalt and one part manganese. These cathodes have a higher energy density, a longer lifespan and provide a better driving range when used in EVs.
As it turns out, lithium hydroxide, which we’ll be producing, is better suited in the production of the batteries with NCM 811 cathodes when compared to its alternative, lithium carbonate. Although lithium carbonate can be converted into lithium hydroxide, it comes at an additional cost and additional steps.
Benefits of hard rock
- More flexibility: The lithium hosted in spodumene can be processed into either lithium hydroxide or lithium carbonate. Brines initially can only be processed into carbonate, and then can be further processed into hydroxide however at an additional cost
- Faster processing: Brines can take a lot longer to process due to the evaporation required making for an inconsistent process compared to spodumene
- Higher quality: Spodumene typically hosts higher lithium content in comparison to most brines
- Comparable costs: While each mining operation may have its own defining factors regarding profitability, hard-rock operations utilize low-cost traditional mining techniques