A worldwide survey on grinding mill circuits in the mineral processing industry was conducted. The aims of this survey are to determine how milling circuits are currently controlled. and to find out how key process variables are linked to economic benefits. The survey involves background information on the circuits, the choice of controlled and manipulated variables, the economic impact of the controlled variables. adopted control technologies and assessment of control performance. Sixty-eight responses were received. Survey results are contrasted to the milling control literature. (C) 2008 Elsevier B.V. All rights reserved.