Rapid Dewatering of Mill Tailings

"This paper describes a process that can provide high rates of dewatering and that has the potential of bringing significant savings in tailing disposal costs. It involves a three-stage, closed-circuit operation employing a hydrocyclone, a settling cone and a thickener. The mill tailing, with adjusted pulp density, is first fed to the hydrocyclone. The underflow from the hydrocyclone goes to the settling cone for further dewatering. The overflows from the hydrocyclone and the settling cone are sent to a thickener which, with the addition of a flocculant, gives a clear liquid effluent and a dilute underflow which is recycled back to the hydrocyclone. The underflow of the settling cone is a material with as high as 78% pulp density and is suitable for direct disposal or for use as mine backfill.INTRODUCTIONDewatering is an essential process for the disposal of mill tailings and forms an additional cost item in milling operations. Cost-cutting measures are therefore desirable in this area as in any other stage of milling. One way of achieving this is through increased rate of dewatering which would require smaller dewatering units with correspondingly lower capital and operating costs."