US Patent 7694829 Settling vessel for extracting crude oil from tar sands

Process and apparatus for the continuous separation of crude oil from tar sands include using a hydrocarbon diluent and an aqueous solution in one or more settling vessels. The light components from the oil are collected and recycled to be used as the hydrocarbon diluent, and the aqueous solution is collected and recycled. A second aqueous solution is introduced in the second and subsequent vessels to prevent the formation of an oil film on the equipment.