| 摘要 |
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 adding the aerated bitumen-depleted aerated middlings material from the air scavenger zone to the mixture of tar sands and water before the settling step.
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