Beneficiation methods for hard rock lithium ore

Common lithium minerals in hard rock deposits include spodumene, lepidolite, lithium-bearing feldspar, and lithium-aluminium phosphate. Among these, spodumene, with its substantial reserves and widespread distribution, constitutes the primary mining target; lepidolite, owing to its favourable flotation properties, also represents an important beneficiation objective.

Currently employed mineral processing techniques chiefly comprise hand sorting, heavy media separation, flotation, magnetic separation, and combined processes:

Hand Sorting Process: Suitable for lithium spodumene with coarse crystalline grain size and distinct identification, serving as a pre-selection method to effectively remove waste rock and reduce subsequent processing costs. For instance, a lithium mine in Sichuan achieved a cost reduction of ¥1.45 per tonne of raw ore through pre-sorting waste rock by hand.

Heavy Media Concentration: Utilises mineral density differences for separation, offering advantages such as simplicity, environmental friendliness, and low cost. A lithium spodumene mine in Sichuan employed heavy media cyclones, achieving a concentrate grade of 6.46% and a recovery rate of 87.47% from ore with an initial Li₂O grade of 3.18%, reducing costs by ¥11 per tonne.

Flotation process: The mainstream method for treating fine-grained disseminated lithium ores. Lithium spodumene can be processed via positive or reverse flotation, while lithium mica yields favourable results under neutral conditions using fatty acid collectors. For refractory ores, techniques such as pre-desliming and staged reagent dosing can still achieve satisfactory indicators.

Magnetic separation and combined processes: Commonly employed to remove magnetic impurities or recover weakly magnetic minerals. Complex, difficult-to-process ores often utilise combined ‘gravity-flotation-magnetic’ flowsheets to achieve comprehensive recovery of lithium alongside associated valuable elements (such as tantalum and niobium).