Abstract: A tank with an upwardly concave bottom, a rotatable center shaft running on the vertical axis of the tank from the top of the tank to the bottom, middlings outlets at the side of the tank, a sands discharge outlet at the bottom of the tank, an overflow means connected at the side of the tank, a sand rake connected to the center shaft to rotate with the shaft and positioned to move settled sand toward the sand discharge outlet and a means for rotating the center shaft, the improvement which comprises a combination of two or more saucer-shaped deflecting baffles located in the cell and concentric with the shaft and affixed thereto, the lowest baffle being located immediately above the sand rake, and inverted to the bottom of the cell and having a skirt extending downward from the outer periphery thereof and at least one other deflecting baffle being located in between the feed well and the lower baffle.

Abstract: In a hot water process for extracting bitumen from tar sands comprising forming a mixture of tar sands and water, settling the mixture in a primary extraction zone to form an upper bitumen froth layer, a middlings layer, and a sand tailings layer, passing a part of the middlings layer to an air scavenger zone to recover additional bitumen therefrom, the improvement which comprises aerating the mixture of tar sands and water before separating bitumen froth from the mixture in a gravity settling zone. This aeration can be accomplished by adding an aerated recycle middlings stream to the tar sands water-mixture prior to the settling step.

Abstract: A method for recovering bitumen from an aqueous stream containing bitumen and mineral matter comprising aerating said stream at a pressure greater than atmospheric and thereafter settling said aerated stream at a lower pressure.

Abstract: An improved separation cell suitable for use in a hot water method for extracting bitumen from tar sands. The improvement lies substantially in the hollow inverted frusto-cone shaped bottom of the cell having a means for injecting hydroseparation liquid into the cavity formed by the frusto-conical bottom.

Abstract: An environmentally attractive method for storing sludge containing water, mineral matter, bitumen, and liquid hydrocarbon formed in a retention pond used to store effluent discharge waste streams associated with aqueous extraction of bitumen from tar sands comprising inserting the sludge below the surface of an unpolluted pond.