Abstract: A sleeve made of rigid tube into which the feed lines for feeding the waste to treated and the gases to be discharged lead. In order to avoid contamination or blockage of the sleeve, a tool for scraping the inner face of the wall thereof is added, in this case a terminal tubular section of one of the feed lines, which carries out orbital movements tangent to this inner face. Various cooling, rinsing and overpressure structures are added, as is a docking device extending at the bottom of the sleeve for connecting the latter to the heat treatment container.