Abstract: Disclosed is a method of combusting hydrocarbon containing materials and equipment suitable for practicing the method in which the materials are burned in a closed chamber at a temperature significantly above the autogenous ignition temperature of the hydrocarbons and the resulting gases exhausted to a separation and classification chamber where additional oxygen is admitted to the high temperature gases to create a secondary combustion zone in the classification chamber. The light hydrocarbon and particulate free gases are allowed to escape from this chamber by thermal convection through a barometrically dampered exhaust stack. All other gases are mechanically induced to return or recycle to the combustion chamber and to enter it at a temperature at least as high as the autogenous ignition temperature of the hydrocarbons.