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

Abstract

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 0.36g/t, which is lower than in the existing flotation circuit (0.47g/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.