Spodumene is a lithium-reach mineral which is used as a raw material for the production of lithium hydroxide. Lithium hydroxide is a crucial component for the manufacturing of cathodes of lithium-ion batteries. The mineral, spodumene' was discovered by the Brazilian naturalist 'Jose Bonifacio de Andrada e Silva' and its name originates from the Greek word 'spodumenos', which translates to "burnt to ashes." The name reflects the ash-grey color of spodumene when it is processed and refined for industrial applications, resembling the appearance of burnt ashes.
Image courtesy: Rob Lavinsky, wikimedia commons
Spodumene is a critical mineral in the lithium supply chain, primarily because it is a well recognized lithium ore and its conversion into lithium compounds is well-established industrially. In the context of the growing demand for lithium-ion batteries, spodumene's role as a source of lithium hydroxide is of increasing importance. Lithium hydroxide is preferred in high-performance lithium-ion batteries due to its ability to produce cathode materials with a higher lithium content, which can deliver better battery performance.
The process of converting spodumene into lithium hydroxide is complex and involves several key stages, as depicted in the flow chart.
Courtesy: Piedmont Chemical Plant Simplified Overall Flowsheet available on sec.gov
The following is a detailed walkthrough of this process:
Calcination: Spodumene concentrate, after being mined and concentrated, undergoes calcination where it is heated at high temperatures to change its crystal structure and enhance its reactivity.
Milling: The calcined spodumene is then milled into a finer powder, which increases the surface area and facilitates the subsequent chemical reactions.
Acid Roasting: The milled spodumene is mixed with concentrated sulfuric acid and roasted at high temperatures, which transforms it into a water-soluble lithium sulfate.
Water Leach & Oxidation: The roasted spodumene is then leached with water, during which lithium sulfate is dissolved into the aqueous phase. Oxidation agents may be used to precipitate impurities.
Neutralization & Impurity Removal: The leachate is treated with calcium hydroxide or sodium hydroxide to remove impurities such as magnesium and calcium through precipitation.
Primary Filtration: The slurry from neutralization is filtered to remove the solid impurities, resulting in a cleaner lithium-bearing solution.
Ion Exchange/Secondary Filtration: Ion exchange resins or additional filtration steps are used to further purify the lithium in solution, removing residual impurities to required specifications.
Evaporation: The purified lithium solution is concentrated through evaporation, removing excess water and preparing the solution for crystallization.
Crystallization: Lithium hydroxide is crystallized out of the concentrated solution. This may occur in stages, starting with crude lithium hydroxide crystallization, followed by digestion, and then pure lithium hydroxide crystallization.
Drying: The crystallized lithium hydroxide is then dried to remove any remaining moisture, resulting in a powdered form of lithium hydroxide monohydrate, ready for use in battery production or further chemical processing.
Throughout the process, there are various steps that involve recycling of reagents and recovery of by-products like sodium sulfate, which is often crystallized and sold separately.
Spodumene is a cornerstone of the global lithium supply chain, which supports the lithium-ion battery industry. As a lithium-rich mineral, it offers a direct and potent source of lithium, which is essential for battery manufacturing. Its high lithium content means that extracting lithium from spodumene is a relatively efficient process, requiring less ore to produce the same amount of lithium compared to other sources, thus ensuring a steady flow of raw material into the battery production pipeline.
Moreover, the conversion of spodumene into lithium compounds is faster than extracting lithium from brine sources, which is a lengthy process. This means that the supply chain can be more dynamic and adjust to market demands more rapidly, a significant advantage in an industry characterized by rapid growth and evolving technology.
The quality of lithium hydroxide produced from spodumene is typically very high, which is a crucial attribute for the performance of Li-ion batteries. High-purity lithium hydroxide leads to better cathodes, which translate to improved battery life, efficiency, and safety, factors that are crucial for the wide-scale adoption of electric vehicles.
Pricing of lithium and lithium hydroxide is intrinsically tied to the costs associated with spodumene mining and processing. As a significant cost component in the production of Li-ion batteries, any variation in the price of lithium can have considerable implications for the pricing of batteries and electric vehicles. Consequently, the entire electric vehicle market is sensitive to fluctuations in the supply and processing costs of spodumene.
The environmental impact of spodumene mining also cannot be overlooked, as it shapes the regulatory framework and operational costs of extraction and processing. Sustainable and environmentally responsible practices in spodumene mining are becoming increasingly important and can influence the overall cost structure of the lithium supply chain.
In the wider context, the role of spodumene is integral not just in the current supply chain but also in the future of energy storage and mobility. As demand for electric vehicles and renewable energy storage solutions continues to surge, the strategic importance of spodumene as a source of lithium will only grow, reinforcing its impact on the pricing and availability of Li-ion batteries and the sustainability of their production.