PROCESS FOR RECOVERY OF RESIDUAL BITUMEN FROM TAILINGS FROM OIL SAND EXTRACTION PLANTS

摘要

IMPROVED PROCESS FOR RECOVERY OF RESIDUAL BITUMENFROM TAILINGS FROM OIL SAND EXTRACTION PLANTSAbstract of the DisclosureBitumen in primary separation vessel underflow and bitumen plus diluentnaphtha in aqueous effluent from centrifugation plants that together representlosses of 8 to 12% of oil in oil sand feed to a hot water extration plant maybe substantially recovered by settling and flotation scavenging after tailingsfractions have been subjected to a tumbling, mixing or shearing process. Theprocess of the present invention includes the possibility of dilution of thesand while raising the bitumen content of the primary separation vessel under-flow by admixture with centrifugation plant tailings, unscavenged primaryseparation vessel middlings or bituminous sludge from a retention pond,subjecting the resulting mixture to a tumbling, mixing or shearing action withincorporation of air or alternative gas bubbles followed by settling of thesand with passive or gas induced flotation scavenging of bitumen which can bepromoted by use of carbon dioxide. By providing a back-up recovery systemcapable of efficient scavenging of residual hydrocarbon the hot water processcan be operated at increased throughput, lower temperatures, reduced sensitiv-ity to clay-water ratios and increased extraction efficiencies.