Abstract
The massive increase of Lithium demand, mainly driven by the development of electro-mobility, is currently leading to a huge number of Lithium exploration and processing projects. Lithium extraction from hard rock-spodumene ore has been increasing, along with the traditional extraction from salar brines.
Metso has the experience and knowledge on the development of sustainable spodumene beneficiation processing flowsheets to increase the recovery and maximize final concentrate quality. The beneficiation process flowsheet comprehends all processing areas ranging from ore sorting, crushing, grinding, regrinding, magnetic separation, flotation, thickening and filtration. The beneficiation flowsheet is designed to maximize water recirculation streams into the concentrator and to minimize effluents into the environment.
Metso has developed and commercialized a novel alkaline leaching process for lithium extraction from hard rock spodumene. The patented hydrometallurgical lithium process has been demonstrated in pilot scale and first reference plants are in implementation phase. Prior to the lithium extraction, the natural α-spodumene containing concentrate needs to be converted to β-spodumene in a kiln process. The alkaline pressure leaching process uses soda ash to extract the lithium from beta-spodumene. Further downstream, hydrated lime is fed to convert extracted lithium to soluble lithium hydroxide. The alkaline process has certain benefits such as selectivity for lithium dissolving only a limited amounts of impurities due to mild conditions and consequently, less downstream purification stages are required, prior to lithium hydroxide monohydrate crystallization.
On-line analyzers have a great potential to improve process efficiencies, reduce chemical consumptions, reduce freshwater consumption, and improve energy efficiency. Traditionally XRF analyzers have been utilized for process control, however they struggle to measure lithium due to the low fluorescence energy. New analyzers have been developed for spodumene beneficiation and battery grade lithium chemical processing. Metso Courier 8X laser-induced breakdown spectroscopy analyzer enables direct lithium measurement in spodumene beneficiation and Courier HX optical emission spectroscopy analyzer system the analysis for hydrometallurgical production of battery grade lithium products.
Metso has developed their process digital twin, GeminexTM, based on dynamic process simulation to address ore variability and increase process performance. The process simulations have been validated with data coming from experiments performed in pilot scale, considering several ore types. These process simulation models contain parameters that are adjusted using on-line data from the connected plant, ensuring a continuous adaptation of the model to the real plant. While the predictive simulation enables to determine best operation conditions for varying ore content, real-time data coming from on-stream analysis helps in controlling the quality of the end-product as well as optimizing the dosage of chemicals – a complete digital solution that uses all available data and allows for continuous maximization of plant performance.