Waste oil recovery by treatment with propanol - after heating to reduce water and ethylene glycol content

摘要

Waste hydrocarbon oils are reclaimed by (a) heating the waste oil at 150-210 degrees C and atmos. pressure, or at the sub-atmos. pressure/temp. equiv., to reduce the water content of the oil to 3 wt.%, and the ethylene glycol content to 15 wt.%, (b) mixing 1 pt. wt. of the treated oil with >=2.2 pts. wt. of isopropanol or >=1.5 pts. wt. of n-propanol, or a proportionate mixt. of these alcohols at 45-80 degrees C, (c) sepg. the undissolved suspended waste matter from the heated oil-propanol soln., and (d) distilling the soln. to separate and recover the oil and the solvent. The oil is not diluted with light hydrocarbons or pretreated with acid or alkali. Only 2 phases are formed, giving easier sepn. The oil has high solubility in the solvents at 45-80 degrees C, and dissolves within 2-120 seconds. The method can be used in continuous plant operation, taking about 30 minutes (compared with 36-60 hours for an acid treatment process). The recovered sludge may contain up to 9% of recoverable Pb and other trace metals, and can be used in sec. Pb smelting. The waste oil is esp. used automobile crankcase oil or diesel lubricating oil and the recovered oil can be used for lubrication without further refining.