Contributed by Andrew Paradis, Staff Geologist, PPM Consultants
In a world increasingly dependent on clean energy solutions, lithium has emerged as a vital element powering the transition to sustainable technologies. From electric vehicles to energy storage systems, lithium-ion batteries have become ubiquitous, providing a powerful and efficient source of energy. However, the global demand for lithium has surged, leading to a growing interest in finding sustainable methods of lithium extraction from minerals. While lithium is not the only element that exists inside a modern battery for an electric vehicle, it is the most attractive for most battery makers. Lithium is highly reactive and stores a lot of energy in a small space, as well as having one of the lowest densities of other metals used in modern batteries. We will explore the various techniques and challenges associated with lithium extraction from minerals, shedding light on the crucial role it plays in the future for green energy.
The Lithium Challenge
Lithium primarily exists in nature in the form of minerals within rocks, and extracting it is no small feat. The three main sources of lithium extraction are lithium-rich brine deposits, spodumene-bearing pegmatite rocks, and clay deposits. While lithium-rich brine deposits in places like the Salinas Grandes Salt Flat in Argentina and the Salar de Atacama in Chile are currently the most significant sources of lithium production, minerals like spodumene and clay are gaining attention due to their abundant reserves. In fact, you have probably recently read about the discovery of what is claiming to be one of the largest lithium deposits in the world and is nestled in the western part the United States. Located in Northwestern Nevada, just south of the Oregon border, lies a potential lithium deposit so large that it would easily dwarf the deposits in Argentina and Chile. Let us dive into the methods of how we mine a couple of different lithium bearing ores and extract this alkali metal.
A Prized Lithium Ore
Spodumene is a lithium aluminum silicate, pyroxene mineral, that contains a significant concentration of lithium. It is primarily found in pegmatite rocks, which are igneous rocks formed from the slow cooling of magma. The extraction of lithium from spodumene involves several key steps. The process begins with mining operations extracting the α-spodumene (alpha-spodumene) rich pegmatite rocks in an open-pit style mine. These rocks are then transported to a processing facility. Once at the processing facility, the mined α-spodumene ore is crushed into smaller pieces, reducing the size of the spodumene crystals for further processing. The crushed spodumene is then roasted at high temperatures (Calcination), above 900 °C to convert it into a more reactive form known as β-spodumene (beta-spodumene). This crucial step prepares the material for further chemical processing. The processed β-spodumene is then subjected to acid digestion, typically using sulfuric acid heated to over 250 °C, to dissolve out the lithium and other impurities. This process results in a lithium sulfate solution. The lithium sulfate solution is then subjected to a chemical process that precipitates lithium carbonate or lithium hydroxide, the final product used in battery production.
A Promising Alternative in Clay Deposits
Another source of lithium extraction gaining momentum is clay deposits, primarily found in the United States and Europe. We are not just talking about “Clay” you find in your backyard or along creek banks, we are talking about a handful of clay forming minerals in the mica and smectite groups. The mineral Lepidolite is considered one of the most abundant lithium bearing minerals on earth. The extraction of lithium from clay minerals is different from that of spodumene in some ways. Starting off, similar to spodumene extraction, the process begins with the mining and crushing of lithium-bearing clay deposits. The crushed clay minerals are then subjected to acid leaching, usually with sulfuric acid or hydrochloric acid. This process dissolves the lithium from the clay, resulting in a lithium-rich solution. As with spodumene extraction, the lithium solution is then subjected to a precipitation process to obtain lithium carbonate or lithium hydroxide.
Challenges in Lithium Extraction
Lithium extraction from minerals presents several challenges. The extraction process, whether from spodumene or clay, is energy-intensive and can offset some of the environmental benefits of lithium-ion batteries if not powered by renewable energy sources. The mining operations can have significant environmental impacts, including habitat disruption and water contamination. Sustainable mining practices are crucial to mitigate these effects. The lithium supply chain is also still evolving, and fluctuations in demand and supply can lead to price volatility and potential supply shortages.
Continued research and development are necessary to improve extraction efficiency and reduce the environmental impact of lithium extraction.
Lithium extraction from minerals is a critical process that underpins the growth of the clean energy sector. As the demand for lithium-ion batteries continues to rise, sustainable extraction methods and responsible mining practices are essential. Spodumene and clay mineral deposits offer promising alternatives to traditional lithium-rich brine deposits, but challenges such as energy intensity and environmental impact must be addressed.
Investments in research and technology are essential to develop more efficient and environmentally friendly lithium extraction processes. By doing so, we can ensure that the power of lithium helps drive a greener, more sustainable future for all.
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Top 10 largest Lithium mines in the world: www.mining-technology.com/features/top-ten-biggest-lithium-mines/?cf-view
Phase transformation mechanism of spodumene during its calcination: www.sciencedirect.com/science/article/abs/pii/S0892687519302948
Lithium Extraction from Spodumene by the Traditional Sulfuric Acid Process: