Process for the hydrogenation reprocessing of used oils

The present invention provides a hydrogenation process for reprocessing used oil into secondary raffinates in the form of lubricating oils. In this process according to some embodiments of the invention, ecologically undesirable byproducts or waste materials are eliminated, without requiring expensive and time-consuming separation stages or reaction conditions, or the use of expensive catalysts. In particular, even severely contaminated oils, i.e. those which contain organo-chlorine compounds, in particular PCB, chlorinated dioxins and dibenzofurane in concentrations above certain limits, can also be reused as secondary raffinates, in particular as lubricating oils. No longer need these substances be destroyed in a high temperature combustion process, for example. As a first step, the coarse solid substances are removed from the used oil. Thereafter, with the addition of hydrogen, a hydrogenation step is conducted in a sump phase at predetermined pressures and temperatures. Then the reaction products are separated into the lubricating oil and byproducts containing solids.