Home Insights Blog Mining and metals blog The Outotec lithium hydroxide process – a novel direct leach process for producing battery-grade lithium hydroxide from spodumene
Mining and metals refining
Dec 11, 2019

The Outotec lithium hydroxide process – a novel direct leach process for producing battery-grade lithium hydroxide fom spodumene

The electric-vehicle (EV) boom, driven by the pressing need to implement solutions and technologies to fight global warming, is driving lithium-ion battery development and production. NMC and NCA are the preferred chemistries for EV batteries because they provide the highest energy densities; both require the lithium feed to be in the form of hydroxide instead of carbonate. Because of this, lithium hydroxide demand is expected to exceed lithium carbonate demand in the next few years.
lithium ore

Outotec has carried out years of extensive R&D on the alkaline leach process concept for lithium extraction from beta-spodumene and has introduced the Outotec Lithium Hydroxide Process, a proprietary technology for refining spodumene concentrates. It offers a direct sulfate and acid-free method to produce battery-grade lithium hydroxide monohydrate from spodumene concentrates. The process is also environmentally sustainable as the residues are inert and easily neutralized.

The Outotec Lithium Hydroxide Process concept is based on a two-stage alkaline leach process. Lithium is first extracted from the silicate mineral in a pressure leaching stage using soda ash. The reaction involves the formation of soluble lithium carbonate and mineral component analcime (NaAlSi2O6·H2O) as the main components. In the second stage lithium carbonate is solubilized in a conversion reaction, producing lithium hydroxide solution and solid calcium carbonate, which will report together with other mineral residues. Lithium carbonate formed in hydrothermal leaching can be converted to lithium hydroxide in a fast reaction with high yields. Overall, the yield from concentrate for lithium leaching extraction typically exceeds 90%.

The alkaline hydroxide and carbonate processing milieu ensure very low solubilities of all the main impurity elements and compounds including Fe, Al, Mg, Ca, B, and P. No additional impurity removal or precipitation stages are needed. Lithium hydroxide PLS is a suitable feed for polishing with IX and further crystallization of the final LiOH monohydrate product.

Direct Leach Process

Outotec has successfully tested and piloted the process with several spodumene concentrates to produce battery-grade end product (>56.5% LiOH·H2O).

The benefits of the Outotec Lithium Hydroxide Process when compared to traditional methods (sulfuric acid roasting, caustic conversion process) include:
• Acid and sulphate-free process
• Inert and neutral mineral residue
• Produces battery-grade LiOH·H2O
• Simple process with fast throughput


The process concept and the results of the recent pilot test work were presented at the ALTA 2019 conference in Perth, Australia.

Read the full paper

Back to Mining and metals refining