This paper reviews recent work done at Universite Laval in the field of column flotation instrumentation and control. The presented control results rely on froth depth and bias sensors. This work establishes that flotation column control could be substantially improved by using different control methods, such as nonlinear, multivariable, and feedforward control. The emphasis is placed on the way the available information, from sensors and quantitative or even qualitative relationships, may be used to reach the control objectives. Laboratory and pilot-scale results illustrate the discussion. (c) 2004 Elsevier Ltd. All rights reserved.