Bitumen froth treatment in the transition region between paraffinic and naphthenic process conditions

Abstract

Listen

Translate article

Bitumen froth treatment is an important process step of the bitumen recovery from oil sands by surface mining. In bitumen froth treatment, water and mineral solids are separated from the target organic bitumen product by using hydrocarbon solvents. Residual water and mineral solids in the bitumen product are detrimental to pipeline transport and downstream processes. Depending on the solvent composition, the commercial naphthenic and paraffinic bitumen froth treatment processes proceed via the oil-water separation mechanisms of coalescence and agglomeration, respectively. This study presents an experimental proof-of-concept for the existence of a transition region at ambient conditions and solvent-to-bitumen ratio of 1.6, where the advantages of the two commercial froth treatment processes may be combined and the drawbacks essentially eliminated. The bitumen product obtained in the transition region is virtually free from residual water and solids (<0.1 wt%), using gravity settling alone, as in the paraffinic process, and the asphaltenes are retained, as in the naphthenic process. The transition region range is determined at 2.2–4.5(±0.2) wt% aromatic or 70–80(±10) wt% paraffinic content of the solvent. Bitumen froth treatment in the transition region recovers a sufficient amount of oil product with gravity settling alone. These findings suggest that conducting bitumen froth treatment in the transition region could increase both hydrocarbon recovery and product quality. This approach may be valuable not only for bitumen froth treatment but also for other oil-water separation processes, such as in situ bitumen recovery.