Experimental study on the mineral processing of a low-grade spodumene ore in Sichuan

With the continuous growth of domestic lithium market demand and consumption, how to efficiently utilize and develop domestic lithium resources becomes an important approach to addressing the bottleneck constraint of lithium resources in China. According to statistics, the proven pegmatite-type lithium resources in China are relatively concentrated in regions such as Sichuan, Xinjiang, Jiangxi, and Hunan. Low-grade spodumene ores are the main part of such lithium deposits and also serve as one of the main sources of lithium chemical raw materials in China. A low-grade spodumene ore, which is obtained from Sichuan and used in this work, has complex compositions and mineral occurrences. Due to the complex relationship between Li-bearing minerals and gangue minerals, grinding easily produces fine mud or overgrinds lithium minerals, which leads to negative effects on the lithium flotation recovery process. The sample ore properties of the Li-bearing minerals, as well as the dissociation characteristics after grinding of the main Li-minerals, are studied. The operation conditions of lithium flotation are systematically optimized. The mineral state characteristics of the rough foam products obtained from different operation times are determined. The separation efficiency of lithium minerals under different middling disposal process schemes is performed in the lab. The result shows that the content of Li₂O is 1.26% in the raw ore. A good separation index of Li₂O is presented by using the flotation process with a branching import flow path, in which the quick flotation for fractionally easy-floating lithium minerals and the regrinding and recleaning route for the slow-floating middles are introduced. It obtains a Li-concentrate with a Li₂O grade of 5.76% and a Li₂O recovery of 86.30%, which presents the Li₂O grade higher by 0.2 percentage point and the Li₂O recovery higher by one percentage point than those of the traditional flotation flowsheet that uses sequential return of flotation middles for spodumene ores. According to the effective mineral liberation, the adaptability of the grinding and flotation system, and the improvement of lithium recovery ratios, the recovery flowsheet of two-stage rougher flotation, three-stage cleaning flotation, and two-stage scavenging flotation for the lithium mineral is recommended. This speed flotation coupled with middling disposal flotation obtains a high-quality concentrate and a good recovery of lithium minerals from the low-grade spodumene ore, which provides an efficient recovery method for low-grade and complicated spodumene ore.