Flocculation of froth flotation tailings from a coal washery

CIM Bulletin, Vol. 72, No. 802, 1979

H. A. HAMZA Research Scientist, Western Research Laboratory, Energy Research Laboratories, CANMET, Department of Energy, Mines and Resources, Edmonton, Alberta

An experimental study of the settling characteristics of a washery effluent originating as tailings from a froth flotation circuit was undertaken by using a systematic approach to select the most appropriate flocculant(s) under predetermined conditions. Selection and evaluation procedures which greatly reduce the effort required to select flocculants are described.The results show that, although different flocculants display superiority at different ranges of dosage, Separan MG 700 (Dow) is the most suitable on absolute economic grounds. Flocculant evaluation is based on a Cost Performance Index (CPI) which expresses the cost offlocculant (€/ton) required to produce a unit settling rate (in./hr).From experiments carried out with a number offlocculant aid and flocculant combinations, it was concluded that the use offlocculant aids can be economically justified only if the settling rates required are higher than those obtainable at the optimum flocculant dosage. Otherwise, the value of the flocculant aid appears to be limited largely to the reduction of supernatant turbidity.
Keywords: Coal preparation, Coal washeries, Flocculation, Flotation, Froth Flotation , Washery effluents, Tailings, Settling rates, Cardinal River Coals Ltd., Reagents