Studies on Clarification of Coal Washery Effluent Using Polymeric Flocculants and Settling Kinetics

Abstract

Settling tests were conducted on the washery effluent using three types of flocculants namely cationic (Telfloc-3674F), anionic (Magna-1011) and non-ionic (Nalco-83370+). For the study purpose coal washery effluent (having pH of 8.72) was collected from a newly commissioned plant-thickener. Tests were conducted by varying the pH of the pulp at three levels of acidic (4.0), alkaline (11.0) and the natural pH (8.72) of the as collected effluent, besides the flocculent dosages varied at four levels (2, 4, 6 and 8 gpt) for each of the flocculants stated. The results of these tests, estimated in terms of initial settling rate and turbidity indicated that; among the three flocculants tested Telfloc-3674F and Magna-1011 gave best results as compared to Nalco-83370+ flocculent at a washery water pH 8.72. The effect of molecular weight of the flocculants on settling of solids in effluent has been established in terms of the kinetics with a characteristic number for each of the type of flocculants used.