NOVELTY - Device (1) for treating a combustion gas, preferably for treating a natural gas, comprises an absorption stage (3) for separation of hydrogen sulfide and carbon dioxide from the combustion gas by means of a scrubbing medium (17), a desorber (5), which is fluidically connected downstream to the absorption stage, for separating hydrogen sulfide from the scrubbing medium, a conversion stage (7), which is fluidically connected to the desorber, for generating sulfur dioxide as a part of an exhaust-gas stream from the separated-off hydrogen sulfide, and a treatment stage.    USE - The device is useful for treating a combustion gas, preferably for treating a natural gas.    ADVANTAGE - The method: uses common washing medium for all the separation methods, and thus it reduces the required amount of washing medium and is carried out in a cost efficient manner; and is carried out in a simple manner with reduced energy emission.    DETAILED DESCRIPTION - Device (1) for treating a combustion gas, preferably for treating a natural gas, comprises an absorption stage (3) for separation of hydrogen sulfide and carbon dioxide from the combustion gas by means of a scrubbing medium (17), a desorber (5), which is fluidically connected downstream to the absorption stage, for separating hydrogen sulfide from the scrubbing medium, a conversion stage (7), which is fluidically connected to the desorber, for generating sulfur dioxide as a part of an exhaust-gas stream from the separated hydrogen sulfide, and a treatment stage, which is fluidically connected to the conversion stage, for separating sulfur dioxide from the exhaust-gas stream by means of the scrubbing medium. The scrubbing medium is used both for separating hydrogen sulfide and carbon dioxide in the absorption stage and for separating sulfur dioxide in the treatment stage. An INDEPENDENT CLAIM is also included for treating the combustion gas, preferably for treating natural gas, comprising separating hydrogen sulfide and carbon dioxide from the combustion gas in the absorption stage by means of the scrubbing medium, separating hydrogen sulfide from the loaded washing medium flowing through the absorption stage into the desorber, producing sulfur dioxide as a part of the exhaust gas stream in the conversion stage from hydrogen sulfide, which is separated in the desorber, and separating sulfur dioxide from the exhaust stream into the treatment stage by means of the scrubbing medium.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of the device.    Device (1)    Absorption stage (3)    Desorber (5)    Conversion stage (7)    Scrubbing medium (17)