Hard Rock Lithium Ore Processing: Methods and Applications

Processing Technologies of Hard Rock Lithium Ores

Hard rock lithium ores are crucial sources of lithium, mainly containing lithium-bearing minerals such as spodumene, lepidolite, and petalite. Based on the characteristics of different minerals and ore endowments, the current main processing technologies include manual sorting, heavy medium beneficiation, flotation, magnetic separation, and combined beneficiation processes. These technologies, through reasonable combination, can achieve efficient recovery and comprehensive utilization of lithium minerals.

1. Manual Sorting Process

Manual sorting is an artificial pre-selection process based on intuitive features such as mineral shape and color, mainly serving as an auxiliary link for subsequent beneficiation. It is applicable in scenarios including: granitic pegmatite-type ores where spodumene has coarse crystal grains and is easily dissociated as single particles, allowing pre-selection of coarse concentrates; or ores where gangue has obvious characteristics and is easily dissociated after crushing, enabling  removal of gangue to reduce subsequent processing volume.
Advantages: Simple operation, which can reduce subsequent beneficiation costs. For example, Sichuan Dexin Mining Lijiagou lithium mine pre-removes 6% of waste rock through manual sorting, reducing the total beneficiation cost by 1.45 yuan/ton of raw ore.
Limitations: Relies on manual experience, with poor working conditions (prominent noise and dust issues).

2. Heavy Medium Beneficiation Process

Heavy medium beneficiation uses a heavy suspension formed by mixing pyrite, magnetite, or ferrosilicon with water as the medium, and realizes separation by utilizing the density difference between minerals and the medium. The core equipment is the heavy medium cyclone.
Applicable Scenarios: Processing spodumene, petalite, and other ores with particle sizes of 0.5~12mm, which can obtain coarse concentrates in advance and discard tailings, reducing subsequent processing load.
Key Technologies: Strict control of feed particle size (reducing the proportion of -0.5mm grade) and separation density (accuracy up to 0.01g/cm³) is required to avoid the impact of medium viscosity on separation efficiency.
Case: A granitic pegmatite-type spodumene ore in Sichuan adopted this process. Under the conditions of raw ore Li₂O grade 3.18% and feed size -16mm, a concentrate with Li₂O grade 6.46% and recovery rate 87.47% was obtained, with the cost reduced by 11 yuan/ton of raw ore compared to single flotation.

3. Flotation Process

Flotation is the main separation method for fine disseminated lithium minerals (such as spodumene and lepidolite), which can be divided into direct flotation and reverse flotation according to the process.

• Direct flotation: After high-concentration stirring and scrubbing in a strong alkaline medium, oleic acid and its soap cation collectors are used to directly float spodumene. Activation with metal cations such as Fe³⁺ and Al³⁺ can improve the concentrate indicators.

• Reverse flotation: In an alkaline medium adjusted by lime, dextrin and starch are used to inhibit spodumene, and cation collectors are used to float silicate gangue minerals.

• Lepidolite flotation: Due to its good floatability with a layered structure, fatty acid collectors in neutral pulp achieve remarkable results. For example, in a lepidolite ore in Inner Mongolia, using CA collector under neutral conditions, a concentrate with grade 3.57% and recovery rate 80.88% was obtained from raw ore with Li₂O grade 1.29%.

4. Magnetic Separation Process

Magnetic separation is mainly used for two purposes: one is to remove magnetic impurities in spodumene concentrates; the other is to recover associated weakly magnetic tantalum-niobium ores.
Case: A foreign lithium polymetallic ore obtained lithium rough concentrate through "one roughing, three cleaning, and two scavenging" flotation, and then through high-intensity magnetic separation, finally obtained spodumene concentrate with Li₂O grade 5.93% (recovery rate 68.06%) and tantalum-niobium rough concentrate (Nb₂O₅ grade 0.0515%, Ta₂O₅ grade 0.176%).

5. Combined Beneficiation Process

For low-grade, fine-grained, and complex refractory lithium ores, a single process is difficult to meet the standards, so combined processes (such as flotation-magnetic separation, flotation-gravity separation-magnetic separation, etc.) are required.
Case: A non-metallic ore in Gansu adopted the combined process of "high-gradient magnetic separation - shaking table cleaning for tantalum-niobium - tailings desliming and flotation for mica". From raw ore with Li₂O grade 0.42%, lepidolite concentrate with grade 3.28% (recovery rate 92.8%) and tantalum-niobium concentrate (recovery rate 55.85%) were obtained.

In summary, the processing technologies of hard rock lithium ores need to be flexibly selected according to ore characteristics. Through the optimization of single or combined processes, efficient recovery of lithium and associated resources can be achieved, providing key raw material support for the development of the lithium industry.