Application of stirred mill to upgrading of graphite concentrate by flotation

It is difficult to obtain high-grade concentrates for layered minerals, such as graphite, by mineral processing due to the existence of impurities between interlayers. Conventional grinding mills are inefficient in liberating the mineral layers. Upgrading a graphite concentrate by re-grinding with a designed stirred mill is investigated in this paper. Better liberation of mineral layers was achieved, compared with a ball mill and a rod mill. Through re-grinding with the stirred mill followed by a two-stage cleaning flotation process, a low-grade graphite concentrate containing 84.59% fixed carbon could be refined to a high-quality concentrate containing 98.62% fixed carbon with a graphite recovery of 94.15%. It is demonstrated that the stirred mill is more suitable for selective grinding, mineral flake protection and upgrading of layered minerals.