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Abstract
Maximization of water recovery in thickeners is an essential step in the mineral processing industries. The Gol-E-Gohar iron 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. A criterion called the index of flocculation incorporating the perimeter-based fractal dimension of floes, floe size, and settling velocities was proposed and used to determine the optimum flocculant dosage which was found to be 20 g/t. The fractal dimension of floes in a pulp containing 5% solids was found to be between 1.16 (no flocculant) and 1.56 (40 g/t flocculant) which indicated highly branched and loosely bound structures for the floes as flocculant dosage increased. At these conditions, the size of the floes which was recorded by a digital microscope increased from 93 μm to 403 μm. A new feedwell with a special design with the aim of preventing floes breakage and maximizing energy dissipation of pulp was constructed and installed. These modifications led to an increase in the thickener drivehead torque from 5% to 18% of the rated torque, indicating a higher bed depth. 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%, decreased the overflow solids concentration from 0.6 % to values smaller than 0.01 % and resulted in a reduction of 27% in water loss in the thickener underflow.

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	All Years to Access Full-Text Export citations Improving performance of the Gol-E-Gohar iron ore concentration plant thickener By Gh. Parsapour, E. Arghavani, S. Banisi, S. Mousavi Published in International Mineral Processing Congress (IMPC) at 2014 Direct link: http://kmpchemmat.ir/pii/42810 Abstract Maximization of water recovery in thickeners is an essential step in the mineral processing industries. The Gol-E-Gohar iron 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. A criterion called the index of flocculation incorporating the perimeter-based fractal dimension of floes, floe size, and settling velocities was proposed and used to determine the optimum flocculant dosage which was found to be 20 g/t. The fractal dimension of floes in a pulp containing 5% solids was found to be between 1.16 (no flocculant) and 1.56 (40 g/t flocculant) which indicated highly branched and loosely bound structures for the floes as flocculant dosage increased. At these conditions, the size of the floes which was recorded by a digital microscope increased from 93 μm to 403 μm. A new feedwell with a special design with the aim of preventing floes breakage and maximizing energy dissipation of pulp was constructed and installed. These modifications led to an increase in the thickener drivehead torque from 5% to 18% of the rated torque, indicating a higher bed depth. 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%, decreased the overflow solids concentration from 0.6 % to values smaller than 0.01 % and resulted in a reduction of 27% in water loss in the thickener underflow.