Characteristics of lithium tailings and evaluation of lithium resource recovery in Manono, DRC

The lithium, tin, niobium and tantalum resources are abundant in Manono, Democratic Republic of Congo （DRC）. During the historical mining activities, the tin, niobium and tantalum minerals are recovered from the chute flowsheet, and the lithium-containing is discharged and stored within the tailings. In order to evaluate the lithium extraction potential from the tailings, the process of mineralogy study and closed-circuit flotation and demagnetization test are carried out on the samples from the K and Gc tailings dumps. The K and Gc tailings dumps are composed of fresh pegmatites classics, and the available mineral resource is 6.9 million tons with Li₂O grade at 0.79%. With the process of mineralogy analysis, the K dump and G dump granulometry distribution P₈₀=1.194 mm （coarse tailings） and 9.58 mm （gravely tailings） respectively. The lithium-containing mineral in the tailing is spodumene with main distribution in medium to coarse grain, the mineral content is 10.32%; the coltan and cassiterite are with fine to medium grain distribution; the other gangue minerals are muscovite, quartz, albite, microcline, etc. The feed ore Li₂O grade at 0.86% is ground to −0.074 mm accounting for 75% and processed by closed-circuit flotation test and demagnetization that is “rougher flotation concentrate is processed third times by cleaner flotation circuit and the rougher tailing is processed in scavenger flotation, the final cleaner concentrate is demagnetized”, and the lithium recovery is 70.47% with the concentrate Li₂O grade at 6.03% classed as the chemical grade. The preliminary economic analysis results show the after-tax IRR is 20.31% and the investment recovery period is 3.91 years. The evaluation work of the Manono lithium containing tailing dumps such as the geological features assessment, process mineralogy and flotation test could be technical guidance for the tailings deposits development.