Deciphering Lithium Sources: Hard Rock vs. Brine

Lithium, the cornerstone of today's battery technology, is fueling a global energy revolution. As the demand for this precious metal rises, understanding where it comes from becomes increasingly critical. There are two primary sources of lithium: hard rock and brine. In this article, we break down the differences between these two types of lithium and discuss their extraction processes.

Lithium from Hard Rock

Hard rock lithium, found most commonly in the form of the lithium-bearing mineral spodumene, is derived from mineral deposits, typically found in pegmatite igneous rocks1. Spodumene is the most important commercially mined lithium mineral due to its high lithium content and favorable metallurgical properties. The Greenbushes mine in Western Australia, one of the world's largest lithium mines, is a significant source of lithium.

The extraction process for hard rock lithium typically involves traditional mining methods. This includes drilling, blasting, loading, and transporting the spodumene ore to the processing plant. Here, the ore is crushed and heated in a kiln before being subjected to flotation or other gravity separation processes, which separates the lithium minerals from the ore2.

Lithium from Brine

Lithium can also be sourced from brines, particularly from salt flats or high-altitude salars. This form of lithium extraction is common in areas such as the Lithium Triangle, a region overlapping Argentina, Bolivia, and Chile, known for its high lithium brine concentrations within high-altitude salars3. The only current brine operation in the US is located in southern Nevada.

The extraction process for lithium from brine involves pumping the brine into evaporation ponds, which accelerates the natural evaporation process, aided by sunlight and wind4. Over a period of months to years, the water evaporates, leaving behind concentrated lithium salts. These salts are further processed to extract lithium carbonate or lithium chloride, which are then converted to lithium hydroxide, the form required for battery production. Recent technological advancements are seeking to bypass the time-consuming and high-water-use method of the traditional natural evaporation in favour of a more energy-intensive process and reach the end-product sooner. Direct Lithium Extraction (DLE) is a method that selectively removes lithium compounds directly from solution. Several variations of the DLE method are being trialed by a handful of companies, but none have yet proven to be viable.

Key Differences

The primary differences between hard rock and brine lithium lie in their extraction processes, costs, and environmental impacts.

1. Extraction process and time: Extracting lithium from hard rock is quicker, taking days to weeks, while extracting it from brine takes months to years due to the slow evaporation process5.
2. Cost: Hard rock extraction generally has higher operational costs due to the energy-intensive mining processes. On the other hand, brine extraction, despite taking longer, usually has lower operating costs6.
3. Environmental Impact: Both methods have environmental considerations. Hard rock mining involves land disruption and can generate substantial waste rock. Brine extraction requires extensive water usage, an issue in the often arid regions where lithium-rich brines are found.
4. Quality: Hard rock lithium generally has higher purity levels, making it more suitable for use in high-quality applications like electric vehicle batteries7.

As demand for lithium grows, driven by the expansion of electric vehicles and renewable energy storage, both hard rock and brine resources will likely continue to play crucial roles in the global lithium supply chain. Advances in extraction technology and environmental mitigation practices will be key to ensuring the sustainability of these vital lithium sources.

Footnotes

1. Spodumene: The Lithium Market, Resources and Processes