Patent ID: 8500864

Claim:
A method of treating crude gases containing methane and carbon dioxide to produce methane, which comprises: a) subjecting the crude gas to a single or multi-stage scrubbing process with an amine-containing scrubbing solution at an amine concentration of at least 15% with the formation of a pure gas stream consisting of methane and water, removing the water from the pure gas stream and, optionally, returning the water to a scrubbing circuit by downstream cooling and condensation; b) compressing a scrubbing solution containing CO 2 and sulfur compounds obtained in step a) to a reaction pressure of at least 4 bar, heating to a temperature above 120° C. and expanding, in an initial expansion stage, to a pressure that is 1 to 3 bar below the reaction pressure, while maintaining a secondary reaction time of 280 to 1200 seconds and a constant reaction temperature, for removing a major proportion of the CO 2 and sulfur compounds from the scrubbing solution and drawing off as a gas stream; c) cooling the thus purified scrubbing solution to a temperature below 50° C. and expanding in a second expansion stage to standard pressure, to remove residual amounts of soluble CO 2 and sulfur compounds still present to form a completely purified scrubbing solution, and cooling the completely purified scrubbing solution to standard temperature and returning to the scrubbing stage.