Improving Oil Sands Processability Using a Temperature-Sensitive Polymer

A temperature-sensitive polymer, poly(N-isopropylacrylamide), was tested as a process aid to process a low-grade, high-fines oil sand ore. Two sets of bitumen extraction tests were carried out. In test set I, both oil sands slurry conditioning and bitumen flotation were conducted at 23 degrees C. In test set II, the slurry was conditioned at 23 degrees C, and, however, the bitumen flotation step was carried out at 40 degrees C. It was found that the use of the polymer in test set I imposed a negative impact on both bitumen recovery and bitumen froth quality. In test set II, the addition of the polymer at the bitumen extraction step improved bitumen recovery and significantly accelerated solids settling of the tailings but deteriorated the bitumen froth quality. The improvement in bitumen recovery and tailings settling at the higher operating temperature was attributed to the change of the polymer from a long, extended structure to a coiled configuration, resulting in the formation of compacted floccules of fine solids. Atomic force microscopy (AFM) was used to directly measure the long-range interaction and adhesion forces of fine solids-bitumen in industrial process water. Results from the AFM force measurements indicated potential slime coating of fine solids on bitumen, thus providing a scientific basis on the reduced bitumen froth quality with the polymer addition.