Abstract: Used oil is rerefined utilizing borohydride reducing agents. The borohydride reducing agent contacts the used oil in an aqueous solution, for example. Contact with the borohydride reducing agent may occur before, during or after distillation or evaporation of the used oil. The disclosed method reduces the concentration of carbonyl compounds and metals and reduces the corrosion characteristics of used oil.

Abstract: Used lubricating oil is rerefined utilizing hydride reducing agents. The hydride reducing agent contacts the used oil in an aqueous solution, for example. Contact with the hydride reducing agent may occur before, during or after distillation or evaporation of the used lubricating oil. The disclosed method reduces the concentration of carbonyl compounds and metals and reduces the corrosion characteristics of used lubricating oil.

Abstract: In accordance with the present invention, a process is provided for removing impurities from heavy and light lube oil fractions that have been obtained from waste lubricating oil. The impurities in the light lube oil fraction are removed utilizing tetrahydrofurfuryl alcohol in an extraction column (10). An oil-rich raffinate has the solvent removed therefrom by steam distillation and stripping at reduced pressure in a distillation tower (20). The heavy lube oil fraction is purified in a manner similar to the purification of the light lube oil fraction. Alternatively, most of the tetrahydrofurfuryl alcohol can be removed from the oil-rich raffinate by mixing the raffinate with methanol in an extraction column. The last of the tetrahydrofurfuyl alcohol is then removed from the oil by steam distillation and stripping at a reduced pressure.

Abstract: Used oil is rerefined by distillation and extraction with tetrahydrofurfuryl alcohol. In accordance with the process, used oil is rerefined by distillation to remove a volatile forecut followed by further distillation with recirculation provisions to obtain the desired fractions of lubricating oil products while reducing the vaporization temperature of the oil. The recycle effect tends to reduce coking and cracking while providing a greater recovery of lubricating oil products through the carrier effect of the light ends. After the desired fractions of lubricating oil have been obtained by the distillation phase of the process, tetrahydrofurfuryl alcohol is utilized in an extraction process to remove impurities remaining in the distilled oil. The tetrahydrofurfuryl alcohol-lube oil mixture is separated into a raffinate and extract stream for distilling and steam stripping the tetrahydrofurfuryl alcohol therefrom.

Abstract: Used oil is refined by distillation to remove a volatile forecut followed by further distillation with recirculation provisions to obtain the desired fractions of lubricating oil products while reducing the vaporization temperature of the oil. The recycle effect tends to reduce coking and cracking while providing a greater recovery of lubricating oil products through the carrier effect of the light ends.In one embodiment of the invention, a waste oil feedstock has water, gasoline and other similarly volatile components removed in a first stage evaporator (16). Heavier fuel, such as fuel oil is then removed in a second stage evaporator (28). A light lube oil fraction is then obtained by distillation with a third stage wiped-film evaporator (40). Finally, a heavy lube oil fraction is obtained by distillation of the bottoms from the evaporator (40) with a fourth-stage evaporator (64).

Abstract: In accordance with the present invention, a process is provided for removing impurities from heavy and light lube oil fractions that have been obtained from waste lubricating oil. The impurities in the light lube oil fraction are removed utilizing tetrahydrofurfuryl alcohol in an extraction column (10). An oil-rich raffinate has the solvent removed therefrom by steam distillation and stripping at reduced pressure in a distillation tower (20). The heavy lube oil fraction is purified in a manner similar to the purification of the light lube oil fraction. The finished heavy and light lube oil may then be subjected to further treatment, such as polishing steps or additives may be blended into the lube oil product depending on the desired use.