POLYMER FLOCCULATION AND COAGULATION FOR SEDIMENTATION OF COPPER FLOTATION TAILINGS

Employing a combination of two types of polyelectrolyte might become n ecessary to enhance both the settling rate of the flocs and the water clarity of a fine-particle suspension in a high-capacity thickening pr ocess. The sequence of addition, mixing, type and dosage of polymer al l affect the overall performance and capacity of a thickening process. For the sedimentation of copper flotation tailings, the cylinder test results showed that two different techniques may be used to achieve t he required performance, i.e., a high settling rate of the flocs and t he deisired underflow density and overflow water clarity. The required performance can be acheived by either adjusting the pH prior to anion ic polyelectrolyte flocculation or using a combination of polymer floc culant and coagulant (dual-polymer system). The dynamic thickening tes t results showed that only the approach using a dual-polymer system is capable of meeting the required performance. The effects of polyelect rolyte dosage, the sequence and numbers of polyelectrolyte addition, t he feed concentration, the bed level and the rake speed on the settlin g rate, underflow percent solids and water clarity were studied in cyl inder tests and in a laboratory dynamic thickening unit. The dynamic t est is especially valuable in evaluating the addition and mixing of po lymers. The results were evaluated quantitatively using total suspende d solids in supernatant, underflow density and capacity per unit of se ttling area per unit of time. The objective of this study was to quant ify and explain some of the parameters involved in the sedimentation o f copper flotation tailings.