Upgrading of solvent extracted Athabasca Bitumen by membrane ultrafiltration

Abstract

This paper reports on solvent extraction processes that have been tested extensively for the separation of bitumen from surface-mineable, oil-bearing deposits. The end result of these processes is a solution of bitumen in a hydrocarbon solvent, usually a light naphtha. The bitumen solution contains only minimal amounts of solids and water; but, because of the constraints of the solid- liquid separation and washing steps, the bitumen concentration in the produced solutions can be quite low. Solvent must be separated from these solutions for recycle back to the extraction step of the process. This is usually accomplished by conventional techniques such as distillation, multiple-effect evaporation, or steam stripping. Sometimes a combination of these techniques is required. As a result of the low bitumen content of the solutions, the energy and capital costs associated with solvent recycle can be substantial. The use of membranes for nonaqueous liquid separations is a recent application of this developing technology. Several patents can be found describing processes for the recovery of solvent used in lube oil dewaxing or the regeneration of used automotive oils. A Japanese company has reported the development of several solvent-stable ultrafiltration membranes for the removal of solids from a number of solvents.more » The use of spiral-wound polysulfone membranes for the recovery of pentane solvent used in heavy oil deasphalting has been described by an American firm.« less