Method for reprocessing waste oils, base oils obtained according to said method and use thereof

Method for reprocessing waste oils and production of high-grade base oils, comprising the following steps:

• A) distillation of the waste oil for removal of low boiling organic fractions and removal of water, wherein the waste oil to be reprocessed is treated with concentrated aqueous potassium hydroxide solution during the distillation step;
• B) distillation under vacuum of the waste oil obtained according to step A) for segregation of fuel oil and diesel fractions with boiling cut of about 170 to 385° C. in form of high grade fuel oils;
• C) non-destructive distillation of the distillation residue from step B) by means of thin film evaporation in vacuum to obtain a lubricating oil fraction, which can be separated, as needed, via a subsequent distillative fractioning step, optionally under vacuum, into boiling cuts of different viscosity states;
• D) if appropriate, non-destructive distillation of the bottom product from step C) in order to obtain a lubricating oil fraction of higher viscosity state than the fraction obtained in step C) which can be segregated, as needed, optionally under vacuum, by means of a subsequent distillative fractioning step;
• E) extraction of the fraction or fractions in the form of lubricating oil fractions or boiling cuts of different viscosity states from step C) and optionally D) with N-methyl-2-pyrrolidone (NMP) and/or N-formylmorpholine (NMF) as extraction medium in order to obtain very high grade base oils.