Y. Xu, T. Dabros, and Hassan Hamza
CANMET Energy Technology Centre-Devon
Natural Resources Canada
Devon, Alberta, Canada
T9G 1A8
In the processing of Alberta oil sands, bitumen is first separated from oil sands as a “bitumen froth” that typically consists of 60% bitumen, 30% water, and 10% solids. The clean bitumen is produced in the froth treatment process, in which light hydrocarbon solvent is added to the bitumen froth to enhance water and solids separation and, in some cases, to reject part of asphaltenes. The process produces tailings that are commonly composted of water, solid particles, asphaltene particles, and residual bitumen with light hydrocarbons. The solvent present in the tailings is recovered in a “tailings solvent recovery unit” through heating and evaporation. In this operation formation of stable foams is frequently observed, which would interrupt the normal operation of this process. In order to understand the formation of foams in this specific system a systematic study has been conducted to identify foaming agents. A laboratory-scale foaming column with hot water jacket was used to observe the foaming behavior and light hydrocarbon vapor is bubbled into a model clay suspension system.
Experimental results indicated that a small amount of surfactant possibly present in the tailings water were not the cause for the observed foaming; instead, fine solids contaminated by bitumen fractions including resins were responsible for the stabilization of foams.