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

摘要

IMPROVED PROCESS FOR RECOVERY OF RESIDUAL BITUMEN FROM TAILINGS FROM OIL SAND EXTRACTION PLANTS Bitumen in primary separation vessel underflow and bitumen plus diluent naphtha in aqueous effluent from centrifugation plants that together represent losses of 8 to 12% of oil in oil sand feed to a hot water extration plant may be substantially recovered by settling and flotation scavenging after tailings fractions have been subjected to a tumbling, mixing or shearing process. The process of the present invention includes the possibility of dilution of the sand while raising the bitumen content of the primary separation vessel underflow by admixture with centrifugation plant tailings, unscavenged primary separation vessel middlings or bituminous sludge from a retention pond, subjecting the resulting mixture to a tumbling, mixing or shearing action with incorporation of air or alternative gas bubbles followed by settling of the sand with passive or gas induced flotation scavenging of bitumen which can be promoted by use of carbon dioxide. By providing a back-up recovery system capable of efficient scavenging of residual hydrocarbon the hot water process can be operated at increased throughput, lower temperatures, reduced sensitivity to clay-water ratios and increased extraction efficiencies.