Reactive oily bubble technology for flotation of apatite, dolomite and quartz

•Separation of apatite from dolomite and quartz by reactive oily bubble flotation•Chemisorption for attachment of reactive oily bubble to apatite and dolomite•Short induction time and high contact angle of reactive oily bubbles•Dolomite depression by sodium silicate in reactive oily bubble flotation of apatite

Reactive oily bubble technology was applied to selectively floating apatite from dolomite and quartz. Kerosene containing 100 ppm fatty acid was chosen to generate reactive oily bubbles. Zeta potential and contact angle were measured to investigate the surface properties of reactive oily bubbles and single minerals. The induction time was determined to evaluate the effect of different bubbles on bubble–mineral attachment. This novel technology was compared with conventional air bubble flotation in which collectors were added in the pulp. A shorter induction time and hence a stronger collecting power of the reactive oily bubbles attaching to the unconditioned minerals than the air bubbles attaching to the collector-conditioned minerals were observed.With the addition of sodium silicate as depressant at pH 9, the induction time of reactive oily bubble attaching to dolomite becomes much longer than that attaching to apatite as a result of smaller contact angle of dolomite than apatite, which is opposite to the case of conventional air bubble flotation with collectors added in the pulp. Therefore, a novel phosphate flotation technology is proposed and tested. In this novel technology, apatite is separated from dolomite and quartz using reactive oily bubble with sodium silicate as depressant, followed by separation of dolomite from quartz with conventional air bubble flotation. The results of micro-flotation tests demonstrated a better flotation separation using the proposed novel technology.