In this work, rougher flotation of low grade copper minerals (0.6-0.7% Cu) was tested in column cells at laboratory scale. A negative bias regime was used in order to create a levitating effect on particle-bubble aggregates to promote gross particle flotation. Over 80% recovery was obtained on the flotation of coarse mineral (100% - 84 mu m) with concentrate grades around 2.7%. The process was not optimized, hence,it may be possible to reach even better results. (c) 2005 Elsevier Ltd. All rights reserved.