Hydrophobic-hydrophilic bubble-particle kinetics in a downcomer

Declining ore grades have been addressed through exponentially higher cell residence times. With cell sizes approaching 1000 m3, improved kinetics is crucial. Downcomers, which increase shear rates for improved recovery of fine hydrophobic particles, may also cause a strong deposition flux of ultrafine hydrophilic particles close to the bubble surface, via lubrication forces. Model feeds of varying silica-to-chalcopyrite mass ratios up to 80 were processed using a REFLUX™ Flotation Cell (RFC™). Equivalent hydrodynamic conditions were applied, including a low solids concentration of 1 wt% to prevent kinetic limitations due to limited bubble surface area. The hydrophobic particle recovery declined significantly as the silica content increased, with clear evidence the ultrafine hydrophilic silica hindered the adhesion kinetics of the hydrophobic chalcopyrite.