Production of Spodumene Concentrate from the North Carolina Piedmont Lithium Project

Abstract.

The global push toward sustainable energy has created a surge in demand for electric vehicles powered by lithium-ion batteries. To meet projections, the mining industry is rapidly expanding to develop new lithium mineral projects focused on producing high-quality lithium concentrates. The Piedmont Lithium Project in North Carolina is located along the Carolina Tin-Spodumene Belt and contains high-grade lithium pegmatites well-suited for producing spodumene concentrate. The study investigated chemical-grade spodumene concentrate production using dense media separation (DMS), magnetic separation, and froth flotation. Three composite samples were selected with varying ratios of pegmatite to host rock and different mineralogical compositions. A two-stage DMS circuit processed the −6.4/+3.3 mm and −3.3/+1.0 mm fractions of each sample and achieved 24–37% with lithium grades ranging from 6.0% to 6.4% Li₂O. The flotation feed was comprised of DMS middlings and the −1.0 mm fines fraction which were stage-ground to −300 μm. Magnetic separation was used to reject iron silicate minerals prior to flotation. Flotation conditions were optimized in a series of bench-scale flotation tests. Locked-cycle tests were conducted under optimized flotation conditions and resulted in global lithium recoveries ranging from 37% to 53% with lithium grades between 5.7% and 6.4% Li₂O. The combined DMS and flotation flowsheet produced lithium recoveries of 74%, 77%, and 80% at combined concentrate grades of 5.8%, 6.4%, and 6.0% Li₂O, respectively.