Effect of particle size distribution on recovery of coarse chalcopyrite and galena in Denver flotation cell

The flotation recovery by particle size of single mineral chalcopyrite and galena was studied in a Denver flotation cell, using sodium dicresylthiophosphate (DTP) and sodium isopropyl xanthate (SIPX) as collectors and polypropylene glycol (PPG) as a frother. The study was extended to very coarse particle size (up to 1.6 mm). Froth stability was also measured in parallel to the batch flotation tests, in a specifically designed froth stability column, following the Bikerman approach. It is shown that particles up to 850 mu m can be floated successfully, provided they are liberated and hydrophobic. However, the recovery of both chalcopyrite and galena was strongly influenced by the overall particle size distribution, decreasing sharply as the fraction of fines (-106 mu m) in the feed also decreased. Rheology measurements showed negligible differences in pulp viscosity, and therefore in the collection zone hydrodynamics, between the different conditions tested. Froth stability, on the contrary, decreased as the feed particle size distribution became coarser. Correlation was found between the amount of fines in the pulp, froth stability and flotation recovery. The recovery of mineral particles is critically dependent on froth stability, which in turn is highly influenced by the overall particle size distribution of the feed material. For these reasons, the study also suggests that it is not possible in batch flotation to determine the rate and recovery of the coarse particle size fractions floating them independently from the fine size fractions.