| 摘要 |
Bitumen is recovered from oil sands in an ambient temperature procedure in which the oil sands first are subjected to attrition in the presence of an aqueous sodium hydroxide solution to form a slurry of pH at least about 11.5. Sand, freed from bitumen, usually is separated from the slurry, which then is diluted with further quantities of aqueous sodium hydroxide solution while maintaining the pH value, so as to provide the bitumen in a form which can be separated from the aqueous phase by flotation. The bitumen is floated off from the aqueous phase comprising a clay suspension and then forwarded to an upgrading operation. A second bitumen flotation also may be effected following addition of calcium hydroxide to the remaining aqueous phase. The clay suspension may be flocculated and dewatered and the resulting sodium hydroxide solution recycled to the attrition and/or dilution steps.
|
