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The hot water process has recovered approximately 90% of the bitumen in oil sands, but the remaining 10% of bitumen and naphtha has been lost to the tailings pond. Recovery of bitumen and non-bituminous combustibles (NBC) from centrifuge, scroll and final tailings has been considered. he "hot water" extraction process has been the preferred T commercial method for isolating bitumen from oil sands. This process recovers approximately 90% of the bitumen in the feed (Camp, 1974). Without extra processing steps, the remaining 10% of the bitumen along with a small fraction of diluent naphtha is lost to the tailings pond, representing a significant energy loss. For example, for a plant producing 2 1,000 m3/d (1 30,000 bbl/d) of synthetic crude valued at, for example, $14/bbl, approximately U.S. $60 million/year worth of bitumen is lost to tailings.To recover additional bitumen and diluent naphtha from the aqueous tailings, techniques such as flotation-scavenging, aeration, flocculation, and sorption have been studied by several researchers. The success of the separation process in a flotation system depends heavily on the proper control of surfaces and interfaces involved in the highly complex mixture of several solid phases forming an aqueous suspension through which air bubbles are dispersed. Davitt (1 975), and Bain and Roberts (1979) have described methods for reprocessing tailings sludge by agitation, aeration, and dilution combined with flotation and skimming, respectively. The tailings sludge has been aerated and agitated to form a bituminous froth layer and a lower layer of mineral and water. Sodium silicate has been added as a process aid to improve bitumen recovery. Hall and Tollefson (1979,

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