A recent study found that chalcopyrite in the Telfer ore could float without a collector whilst pyrite did not float without a collector in the laboratory. in comparison of the flotation result with and without a collector, the two grade recovery curves are clearly separated due mainly to less pyrite recovery and higher concentrate grades produced by collectorless flotation. Pre-aeration tended to promote collectorless flotation of chalcopyrite while it had a negligible effect on pyrite flotation. In addition to the laboratory study, pulp potential measurements were conducted in the plant. The results indicate that chalcopyrite is likely to retain its collectorless floatability after SAG milling. This may provide an opportunity of using a flash unit for collectorless flotation on the SAG mill discharge stream. (C) 2010 Elsevier Ltd. All rights reserved.