Significance of exposed grain surface area in coarse particle flotation of low grade gold ore with the hydrofloatTM technology
Conventional flotation machines are typically limited to a particle topsize of 150 200 microns due to inherent constraints created by the pulp and froth phases. To overcome these limitations, a novel fluidized bed flotation system called the HydroFloat TM Separator has been developed specifically for the purpose of floating coarse particles containing only small amounts of exposed hydrophobic minerals. Over the last decade, this technology has been successfully applied to industrial minerals with several full scale units installed to recover particles up to and exceeding 3,000 m diameter. More recently, sulfide based test work has shown that this novel device is also capable of recovering metalliferous values at a grind size that is much coarser than currently used in industrial concentrators. In the current study, high resolution Xray microtomography (HRXMT) was used to experimentally compare the degree of exposed grain surface area necessary to recover coarse particles using the HydroFloat TM technology to that attainable using a traditional mechanical flotation cell. The data indicate that exposed grain surface area is a critical factor for coarse particle flotation. For the gold bearing sulfide ore examined in this study, the HRXMT data suggest that near complete recoveries of coarse (850x500 m) multiphase particles containing as little as 1% exposed grain surface area were realistically attainable using the HydroFloat TM technology. As such, this new technology may offer a unique opportunity for increasing concentrator capacity by increasing the primary grind size needed for rougher/scavenger separations.