Synthesis and Characterization of Amylopectin-grafted Polyacrylamide (AP-g-PAM) Flocculants for Dewatering of Oil Sands Mature Fine Tailings (MFT)

Abstract

Oil sand mining continues increasing in Alberta and bitumen production from surface mining is predicted to reach 257,600 m3/day by 2026 (a 41.3% increase compared to 2016), generating a large amount of tailings that need to be stored in tailing ponds. The challenging part of tailing management is to dewater mature fine tailings (MFT), as the fine solids dispersed in MFT are not easily separated from water by gravity. A possible way to conquer this challenge is to use polymer flocculants to dewater MFT. This research evaluates the performance of amylopectin-graft-polyacrylamide (AP-g-PAM) to flocculate and dewater MFT. Polyacrylamide was grafted on the amylopectin backbone by free radical polymerization using ceric ammonium nitrate (CAN) as an initiator. AP-g-PAM samples were studied by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Different grades of AP-g-PAM were synthesized and tested to flocculate MFT. The flocculation performances of the graft polymers were compared with those of commercial polymers based on the supernatant turbidity, sediment solids content, and capillary suction time (CST). Compared to PAM, it was shown that AP-g-PAM was able to form flocs with higher solids content.