Hydrocarbon-contg. mixt. sepn. by solvent extn. - esp. for treating oil sludge from bitumen prodn. from tar sands

摘要

Sepn. of a mixt. of water, solids or sludges, difficultly volatile hydrocarbons and other accompanying materials, by solvent extn., involves (a) feeding the water- and solvent-diluted and preheated mixt., after solvent extn., to a mechanical sepn. and dewatering stage in which the mixt. is sepd. into a water- and solvent-rich phase contg. the dissolved hyudrocarbons and a solvent-contg. solids-rich phase; (b) feeding the water- and solvent-rich phase to a multistage solvent recovery stage, in which the solvent is evaporated for return to the extn. reactor, the enriched hydrocarbons are removed by skimmers and the skimmed water is fed to the water withdrawal point and/or the heating station; (c) sepg. the solids-rich phase from solvent by solvent stripping, the solvent then being fed to the multistage solvent evapn. unit; and (d) supplying the residual solids as fill material or as clean soil for further use. USE/ADVANTAGE - The process is used esp. for treating the thickened sludge from settling ponds in bitumen prodn. from tar sands, but may also be used to clean soil contaminated by oil spills. Oil-contg. sludges, which pose a permanent environmental risk, are sepd. into their main components, the recycled water is hydrocarbon-free and the process has low energy and operating costs.