Water soluble polymeric nanofibres for rapid flocculation and enhanced dewatering of mature fine tailings

Abstract

Water‐soluble polymer flocculants have been used to efficiently release entrapped water in oil sands tailings by bridging fine particles to create large heavier flocs which can then settle faster and release water more efficiently. Due to their initial interaction with the fine particles suspended in tailings, polymer nanofibres may perform better than their parent polymers because of the entire surface of the nanofibres being fully accessible to the fine particles. In this work, commercially available poly(acrylamide‐co‐diallyl dimethylammonium chloride) was chosen as a basis for this study. Initial settling rate, supernatant turbidity, water recovery, capillary suction time, and solids content were measured to determine the effect of polymer nanofibres on solid‐liquid separation. The solid forms of the polymer (either as nanofibre or powder) perform better than the polymer solution in each test, with optimum dosages of 5 wt% mature fine tailings (MFT) loading. Nanofibres could achieve settling rates of 60 m/h, while the other forms were only able to achieve 42 m/h. Additionally, the turbidity of the supernatant obtained after flocculation with nanofibres was 15 nephelometric turbidity units (NTU), while the polymer solution and powder produced turbidites of 162 NTU and 70 NTU, respectively. In addition, polymer nanofibres and powders generated larger flocs compared to the polymer solution, which produced small, homogenized flocs.

Flocculating and dewatering of kaolin suspensions with different forms of poly(acrylamide‐co‐diallyl dimethylammonium chloride)

“…For further insight to the nanofibre fabrication process, refer to the authors' previous publication. [ 18 ] Powder form of the polymer solution was obtained by freeze‐drying the bulk solution for 1‐2 days. The recovered solid polymer was then ground down to a fine powder with a mortar and pestle.…”