Technical Optimization And Mechanism Study Of Ionic Liquid Enhanced Solvent Extraction Of Bitumen From Oil Sands

Oil sands is regarded as a good alternative energy sources of crude oil, it has avery significant reserve. It comes some problems, such as oil price rising which has anegative influence on the economic and our daily life, caused by the a sharp decreaseof the crude oil reserves and the increase of the oil processing difficulty. For thisreason, the development and improvement of oil sands processing technologies hasdrawn much researcher’s attention.Both of traditional water extraction process and solvent extraction method toextract bitumen from oil sands have their drawbacks, such as sand/clays entraininginto bitumen, bitumen ramining in the residual sands, and the organic solvents areextremely flamble and not environment friendly.To solve these problems, an ionicliquid （[Emim]BF₄） was used to enhance bitumen recovery from the Canada oil sandsby ethyl acetate/n-heptane. The bitumen recovery ratio and the the cleanliness ofbitumen and residual sands were studied. Results show that the optimal volume ratioof ethyl acetate to n-heptane is1:2. Meanwhile [Emim]BF₄increased the bitumenrecovery ratio to93.18%, which is6.86%higher than composite solvent extractionwithout [Emim]BF₄. Negligible clay and fines entrained in the extracted bitumen, andno IL or bitumen residue in the treated sands.Asphaltene is a component of bitumen which is difficulty to process, an ASTMstandards was used to analyse the bitumen four frictions （SARA） distribution in thispaper. The result show that: for the same quality of oil sands, the asphaltene recoveryratio of [Emim]BF₄enhanced composite solvent extraction process and compositesolvent extraction process was1.02%and1.07%, respectively. Another three frictionsrecovery ratio of the former extraction process was0.99%lager than the latter one. Itindicated that [Emim]BF₄facilitated the extraction of the bitumen light frictions. Forthe same quality of bitumen, the asphaltene obtained by solvent extraction amendedby [Emim]BF₄is1.7%lower than that obtained by pure solvent extraction, which ismore beneficial to the downstream processing of bitumen.To a better understand the mechanism of [Emim]BF₄enhanced the solventextraction process, the forces between silica sphere and bitumen/silica waferimmersed in [Emim]BF₄,1mM [Emim]BF₄aqueous solution,1mM KCl aqueous solution and pure water was conducted by atomic force microscopy（AFM）. The resultpresent in this paper show that: the rank of adhesion force between silica sphere was[Emim]BF₄（⁵.5nN）<pure water（¹2.5nN）<1mM KCl（¹4.5nN）<1mM [Emim]BF₄（²2.5nN）. The adhesion force was the smallest in [Emim]BF₄, undoubtelly, thedecreas of adhesion force is a major factor in the relative higher bitumen recoveryrecovery ratio and the separation cleanliness observed in [Emim]BF₄. DLVO theory isinapplicable to interpret and rationalize the force curves in [Emim]BF₄circumstance.