A process for the enhancement of the byproducts of a process for the regeneration of exhaust oils is described, wherein said process for the regeneration of exhaust oils which includes at least one of the following steps: a) passing of the oil to be regenerated into one or more centrifuges, b) storage of the oil, before treatment, in suitable containers, c) desiloxanation and d) filtering. The byproducts of one or more of steps a) to d) are treated, gathered and mixed with one another and added to the bitumen coming out as tail of a fractioned distillation step of the above-said regeneration process of exhaust oils. A plant for the carrying out of a process according to any one of the preceding claims is also described, comprising a processing unit for each of the byproducts coming from steps a) to d) and a mixer (6) with stirring (7).

A method for hydrotreating and recycling waste lubricating oil, the method comprising the two steps of slurry bed pre-hydrotreatment and deep hydrotreatment, specifically as follows: mechanical impurities are removed from waste lubricating oil, and then the oil is subjected to flash distillation to separate free water and a portion of light hydrocarbons; a bottom product of the flash distillation column is mixed with hydrogen and a self-sulfurizing oil-soluble transition metal catalyst, and then enters a slurry bed reactor for pre-hydrotreatment; a liquid product obtained by performing separation on a reaction effluent is subjected to hydrocyclone separation and solvent washing to remove solid residue, and then a pre-treated lubricating oil component is obtained; said component is mixed with hydrogen and then enters a hydrofining reactor, an isomerization-dewaxing reactor, and a supplementary refining reactor, connected in series, for hydrotreatment; and the reaction products are separated to obtain high-quality naphtha, diesel oil and a lubricating base oil. The method of the present invention has such advantages as simple processing procedures, a high oil liquid yield, good lubricating oil base oil quality, and can implement full-fraction resource utilization of waste lubricating oil. In addition, the oil-soluble catalyst features simple dispersion, no need for vulcanization, a small catalyst adding amount, high low-temperature hydrogenation activity, is capable of effectively preventing the coking that could occur during a process of preheating the waste lubricating oil, and ensures long-term stable operation of the device.

A liquid composition for use in purifying an oil contains a polar polymer, a surface active hydrotrope/solubilizer, and a co-tenside. The polar polymer may be a polyalkylene glycol, such as polyethylene glycol. The hydrotrope/solubilizer may be an anionic sulfonic acid, a phosphate ester-based substance or a non-ionic surfactant from the poly-glycoside family. The co-tenside may be at least one amphoteric co-surfactant, such as sodium caprylimino dipropionate.

Provided is a method for recycling a cold-rolled oil sludge, including the following steps: mixing methanol with the cold-rolled oil sludge to obtain a mixture, and subjecting the mixture to esterification under supercritical conditions to obtain a solid-liquid mixture; subjecting the solid-liquid mixture to solid-liquid separation to obtain an iron filing and a liquid phase; and subjecting the liquid phase to methanol removal and extraction in sequence to obtain an oil phase product and an aqueous phase product.