gh.a parsapour - Mining Group, Vali-E-Asr University of Rafsanjan, Rafsanjan, Iran
e arghavani - Kashigar Mineral Processing Research Center, Kerman, Iran
s.m mosavi - Gol-E-Gohar Mining and Industrial Company, Gol-E-Gohar Iron Ore and Steel Institute, Sirjan, Iran
s banisi - Mineral Processing Group, Shahid Bahonar University of Kerman, Kerman, Iran

Maximization of water recovery in thickeners is an essential step in the mineral processing industries. The Gol-E-Gohar iorn ore processing plant uses a center pier thickener with a diameter of 38 m and depth of 4 m. The feed rate is 50 t/h solids with a concentration of 5% (w/w), and it has been designed to provide an underflow containing 50% solids. The performance of the thickener was not as expected judged by the overflow stream containing 0.6% solids and water loss of 52 m3/h in the underflow. Two new feedwells with a special design with the aim of preventing flocs breakage and maximizing energy dissipation of pulp was constructed and installed. Installing of these feedwells in addition to process modifications led to an increase in the thickener drivehead torque from 5% to 18% of the rated torque. Finally, installation of a PID controller reduced the drivehead torque relative oscillation from 52.0% to 12.7%. These changes increased the solids concentration of the underflow from 49.0% to 56.9%, and resulted in a reduction of 27% in water loss in the thickener underflow

Thickener, Flocculation, Feedwell, Torque