Abstract:
This work investigates how poly(vinylbenzyl trimethylammonium chloride)–poly(VBTMAC)–flocculates oil
sands mature fine tailings (MFT). This water-soluble cationic polymer contains pendant benzene rings that make
it partially hydrophobic. The positive charges on the poly(VBTMAC) backbone neutralize the negatively-charged
MFT clays while the hydrophobic benzene rings help expel the water trapped in the aggregates. Vinylbenzyl
trimethylammonium chloride can be polymerized to produce long chains (comparable to anionic polyacrylamide) with fast polymerization rates. Focused beam reflectance measurement (FBRM) experiments showed
that larger aggregates were formed using higher molecular weight poly(VBTMAC), which is evidence of the
bridging mechanism. The flocculation performance of poly(VBTMAC) was tested against commercially available
anionic polyacrylamides for undiluted MFT by measuring the extent of dewatering in filtration tests and the
rheological properties of the sediments. Our results showed that poly(VBTMAC) is a better flocculant in terms of
ease of production, fast dewatering rate, and formation of sediments with high shear strength, but required
substantially higher dosages to perform better than commercially available anionic polyacrylamides.
