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The Need of High Purity Lithium Hydroxide
The electrical vehicle (EV) market is undergoing a revolution transforming the transportation landscape using lithium-ion battery technology. The demand for electric vehicles is not just increasing; it's projected to skyrocket over five times the 2022 production values by 2031. To meet this challenge, high-purity lithium hydroxide and lithium carbonate are required as essential materials for the formulation of these batteries.
The primary sources of lithium are brine lakes (Salars) and mineral deposits, mainly Spodumene ore. The Spodumene ore contains up to 6 % lithium. Conventional mining operations extract minerals from the ground through either underground pit excavation or surface strip mining, depending on the location of the mineral lode.
What is the Lithium Hydroxide Process?
The lithium hydroxide process involves converting lithium carbonate into lithium hydroxide through a chemical reaction with calcium hydroxide (slaked lime). Here's how it works:
- Dissolution: Lithium carbonate is dissolved in water to form a solution.
- Reaction: The solution is reacted with calcium hydroxide, precipitating calcium carbonate and forming lithium hydroxide in solution.
- Filtration: The lithium hydroxide solution is filtered to remove calcium carbonate.
- Concentration & Crystallization: The filtered solution is concentrated and crystallized to produce battery-grade lithium hydroxide.
Process to Convert Lithium Carbonate to Lithium Hydroxide
The process to convert lithium carbonate to lithium hydroxide involves first dissolving lithium carbonate in water to form a lithium carbonate solution. This solution is then reacted with calcium hydroxide (slaked lime) to precipitate calcium carbonate and form lithium hydroxide in solution. Finally, the lithium hydroxide solution is filtered to remove the precipitated calcium carbonate and then concentrated and crystallized to produce battery-grade lithium hydroxide.
Filtration Steps in the Lithium Hydroxide Process
| Filter | Filtration Value | Separation Product |
|---|---|---|
| 1 | Prevent ingression of impurities into system from feed Lithium Carbonate solution | 1 - 5 Micron Filter |
| 2 | Prevent ingression of impurities into system from injected hydrated lime solution | 1 - 5 Micron Filter |
| 3 | Recover fine Lithium Hydroxide particles and protect Ion Exchange (IX) from carryover solids coming from the centrifuge | Regenerable Filter |
| 4 | Remove trace solids and Ion Exchange resin fines before the crystallizer | 1 Micron Filter |
| 5 | Recover fine particles of Lithium Hydroxide from mother liquor recycle and water wash streams | Regenerable Filter |
| 6 | Protect RO filtration unit from fouling enabling consistent supply. RO water used to rinse final product | 10 Mircon Filter |
| 7 | Recover fine particles of Lithium Hydroxide from mother liquor recycle and water wash streams | Regenerable Filter |
Frequently Asked Questions
What is the lithium hydroxide process?
The lithium hydroxide process involves dissolving lithium carbonate in water, reacting it with calcium hydroxide (slaked lime) to form lithium hydroxide in solution, and then filtering, concentrating, and crystallizing it to produce battery-grade lithium hydroxide.
Why is lithium hydroxide preferred over lithium carbonate in some EV batteries?
High-grade lithium hydroxide is often preferred for use in cathode materials due to its compatibility with high-performance battery chemistries. It can offer better performance in certain EV applications compared to lithium carbonate.
What are the challenges in converting lithium carbonate to lithium hydroxide?
Many lithium carbonate production plants are not designed to produce battery-grade lithium hydroxide. Challenges include limited access to fresh water, infrastructure limitations, and the need for specialized conversion facilities—many of which are currently located in China.
What role does filtration play in lithium hydroxide production?
Filtration is critical at multiple stages of the lithium hydroxide process. It removes impurities from feed solutions, protects ion exchange systems, recovers fine lithium hydroxide particles, and ensures the final product meets battery-grade purity standards.
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