NOVELTY - Continuous process for thermal treatment of a refinery sludge, comprises: drying of the refinery sludge possibly mixed with pet-coke at 110-120 degrees C; gasification of the dried sludge at 750-950 degrees C for 30-60 minutes in the presence of a gas containing oxygen and water vapor with the associated production of synthesis gas (carbon monoxide and hydrogen) and a solid residue; combustion of the synthesis gas at 850-1200 degrees C and recycling of the combustion products for the drying and gasification phases; and inertization of the solid residue at 1300-1500 degrees C by vitrification with plasma torches.    USE - The continuous process is useful for thermal treatment of a refinery sludge (claimed), where the refinery sludge is oil sludge, sludge deriving from the treatment of wastewater and biological sludge.    ADVANTAGE - The process: provides reduction in the solid volumes greater than 80% and enables the production of inert products from the remaining part of solid waste; provides an alternative solution at least to disposal in dumps; provides a gaseous volumes (syngas) which is capable of thermally self-sustaining the volume reduction process; does not require other heating source for sustaining the process; and exhibits high efficiency and low heat dispersion.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for apparatus for the thermal treatment of refinery sludge, comprising: (i) a first chamber, a drying chamber, rotating around its longitudinal axis tilted with respect to the horizontal, indirectly heated internally by means of at least one radiating tube (13), inside which the fumes (7) coming from a combustion chamber (10) flow, the radiating tube is such as to contain at least a further coaxial tube in which a mixture consisting of a gas containing oxygen and steam is circulated, for a subsequent gasification phase; (ii) a second chamber, a gasification chamber (3), in communication with the first chamber rotating around its longitudinal axis coinciding with that of the first chamber in which the further coaxial tube extends for a differentiated and incremental injection of the gas mixture containing oxygen and steam; (iii) a third chamber, a combustion chamber in communication with the second chamber into which a gaseous phase is fed, essentially consisting of carbon monoxide and hydrogen (synthesis gas) and product of the gasification reaction (ii); and (iv) a fourth chamber, an inertization chamber (5) in communication with the third chamber for the vitrification of the solid residues.    DESCRIPTION OF DRAWING(S) - The figure shows a longitudinal section of the apparatus.    Gasification chamber (3)    Inertization chamber (5)    Fumes (7)    Combustion chamber (13) Radiating tube (10)