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Metso’s sulphate-free alkaline pressure leach process wins Planet Positive accolade

Metso is expanding its sustainable offering for the lithium market, having validated its proprietary, sulphate-free alkaline pressure leach process as a Planet Positive technology for the production of battery-grade lithium.

Metso’s hydrometallurgical alkaline leach process is a simple and safe way to refine spodumene concentrate to battery-grade end products like lithium hydroxide monohydrate and lithium carbonate, the company says. The innovative refining process produces high-purity lithium salts and hydrates, which are needed for the cathodes of lithium-ion batteries used in electric vehicles.

In the process, lithium is extracted with high yield. Inert and neutral mineral residue is minimised and ready to be reused or disposed of, thus minimising pollution to air, water and soil. No additional impurity removal or precipitation stages are needed. In recent studies, the alkaline leach process has also shown reduced environmental impact compared with other technologies, Metso says. Based on the Life Cycle Impact Assessment, the process can provide an up to 40-60% reduction in water consumption, as well a reduction in the acidification and eutrophication impact. The compact process also minimises plant footprint and embedded carbon, according to Metso.

Metso has been developing sustainable alkaline leaching technologies for hard-rock lithium sources for 20 years already. Today the offering includes proprietary technologies for refining lithium from spodumene mineral concentrates. Intensive R&D and piloting is also ongoing in the processing of other lithium-bearing pegmatite hard rocks such as petalite, zinnwaldite (with Zinnwald Lithium plc) and lepidolite. Metso says it also has proven processes also for the extraction of lithium from brines.

Alongside this, Metso is providing its Planet Positive sustainable soda pressure leaching technology for Keliber’s lithium hydroxide refinery, which will be built in Kokkola, Finland.

Marika Tiihonen, Technology Manager for Lithium at Metso, said: “The urgent need to implement solutions and technologies limiting global warming is driving the development of lithium-ion batteries that are used, for example, in electric vehicles and renewable energy storage ecosystems. This, and the regionalisation of critical minerals sourcing, has resulted in a surge in lithium projects. Currently, Metso is supporting several battery minerals projects that are in study, piloting, engineering or delivery phases.”

Tiihonen added: “As a strong and reliable partner for the development of lithium hydroxide and other battery minerals projects, Metso can deliver the whole production process – from mine to battery materials, and recycling of black mass – complemented with world-class service support.”