Flocculation of oil sands tailings by hyperbranched functionalized polyethylenes (HBfPE)

We synthesized a series of hyperbranched functional polyethylene (HBfPE) flocculants with functional group contents ranging from 30 and 50 mol%, and used them to flocculate oil sands mature fine tailings (MFT). MFTs (diluted to a concentration of 20 wt%) treated with the novel HBfPE had higher settling rates, lower capillary suction time (CST), and lower turbidity than when treated with a reference polyacrylamide (PAM). Within the HBfPE series, the settling performance improved when the functional group content in the copolymer increased. When combined with centrifugation, the HBfPE flocculants generated sediments with higher solids contents than PAM within a shorter centrifugation time. This may be attributed to the tendency of HBfPE to form smaller flocs that compact more tightly than PAM. Floc development for HBfPE and PAM was compared with focused beam reflectance measurement (FBRM). While floc formation with HBfPE and PAM was similar, it required significantly less mixing energy for optimal performance, due to the significantly lower molecular weight (<10,000 g/mol) of HBfPE.