US Patent 7909989 Method for obtaining bitumen from tar sands

A method and a system for obtaining bitumen from tar sand are disclosed. The disclosed method can include two extraction steps, such as a first extraction step using a light aromatic solvent and a second extraction step using a volatile hydrocarbon solvent. The light aromatic solvent and the volatile hydrocarbon solvent both can be recycled and used in multiple extractions. Each extraction and recycling step can include a separation. The disclosed system can include separators configured to perform these separations. Some of these separators also can function as mixers. Using the disclosed method and system, it is possible to achieve a high degree of bitumen recovery while minimizing undesirable complications, such as swelling of clays in the tar sand and/or precipitation of asphaltenes.