Impact of salinity on warm water‐based mineable oil sands processing

Abstract

AbstractContinuous use of caustics and increased level of water recycling inevitably increase the salinity of process water, which is a growing challenge in the current warm water‐based bitumen extraction process. The current study aims at understanding how salinity of process water affects bitumen recovery from mineable oil sands ores. Laboratory flotation results showed an ore‐dependent effect of salinity on bitumen recovery and froth quality. Processing of low‐grade ores suffered a dramatic loss in bitumen recovery with increasing NaCl up to 4000 ppm (i.e. 1574 ppm Na+) at pH 8.5, while only a marginal effect of salinity was found on the processability of a high‐grade ore. The use of caustics as a conventional approach to increase bitumen recovery and froth quality of poor processing ores showed a more severe negative impact of salinity on the processability of low‐grade ores. Salt addition was found to be detrimental to bitumen liberation and bitumen‐bubble attachment in the presence of fines, more so at higher pH of processing water. Increasing salt concentration in solution led to a significant decrease in the magnitude of negative zeta potentials for both bitumen and fine solids. These findings provide scientific guidance to searching for remediation strategies other than using caustics. Such an approach studied was the blending of low‐grade ores with high‐grade ores to minimize the negative impact of increased salinity in recycle water on bitumen extraction.