Recovery of fine gold loss to tailings using advanced reactor pneumatic flotation ImhoflotTM

Gold concentration usually consists of gravity separation and froth flotation. However, flotation faces difficulties due to gold-bearing ores often being refractory and finely disseminated in nature. Poor recovery and low flotation kinetics of fine particles are mainly due to the low frequencies of particle-bubble collisions and an increase in entrainment of fine gangue particles decreases the grade. In this study, applications of two pilot ImhoflotTM G-14 (tangential feed to the separator vessel with 1.4 m diameter) cells in an open circuit demonstrated its ability to recover fines with high gold grade and achieved a high recovery of 65–68 % for the particle size fraction of −20 µm. The gold content in the −20 µm fraction of tailings is only about 0.36 g/t, which is lower than in the existing flotation circuit (0.47 g/t), including rougher and scavenger banks. Furthermore, bubble size measurements indicate that pneumatic ImhoflotTM generated very fine bubbles in a high shear environment, improving particle-bubble collision frequencies.