Aggregation and Sedimentation of Fine Solids in Non-Aqueous Media

Abstract

Environmental concerns about water-based extraction necessitate the development of an alternative non-aqueous extraction method. One of the challenges that any non-aqueous extraction process is encountered is the elimination of suspended fine solids from solvent-diluted bitumen. This study focuses on the fundamental science behind the paraffinic froth treatment process to provide a real insight into the role of asphaltenes in removal of unwanted suspended particles from bitumen froth. We examined the aggregation and sedimentation of model solid in mixture of solvents and bitumen or de-asphalted bitumen using a sedimentation balance. The solvents were heptane, toluene or a mixture of the two known as heptol. The model solids were micron-sized bitumen-coated silica particles. In a set of experiments, the effect of aromatic content of the solvents on sedimentation behavior was investigated. The results showed that the sedimentation behaviors of bitumen coated silica particles are highly sensitive to the aromatic content of the organic solvents. The experiments involved quantifying the settling rates of the particles as the aromatic content of the solvent was varied. The results showed that, in addition to being captured by asphaltene networks, the suspended solids could also homo-flocculate _and thus form aggregates and be separated _in an heptane-diluted bitumen environment. The results indicate that it is possible to control the stability fine particulates in oil, through tuning the aromaticity of the organic solvents.