A method for separating gases, wherein said method is carried out in an apparatus which comprises: a feed stream separation stage, a retentate separation stage and a permeate separation stage, and optionally a compressor arranged up-stream of the feed stream separation stage and/or at least one vacuum device arranged in at least one permeate stream of the feed stream separation stage, the retentate separation stage and/or the permeate separation stage, wherein the feed stream separation stage separates a feed stream comprising at least two components into a first permeate stream and a first retentate stream, and the retentate separation stage separates the first retentate stream into a second permeate stream and a second retentate stream, and the permeate separation stage separates the first permeate stream into a third retentate stream and a third permeate stream, and the second retentate stream is removed as a first product or further processed or optionally can be discarded if the third permeate stream is removed or further processed; and the third permeate stream is removed as product or further processed or optionally can be discarded if the second retentate stream is removed or further processed, and the second permeate stream and the third retentate stream are fed to the feed stream, and the first permeate stream is preferably not subjected to a recompression, and the feed stream separation stage, the retentate separation stage and the permeate separation stage are membrane separation stages, and the gas volume recycled in the second permeate stream and in the third retentate stream totals 60 to 100 % by volume of the crude gas stream, and the total capacity of the membranes, measured for nitrogen Grade 4.8 under standard conditions as defined in the description, used in the retentate separation stage is higher than the total capacity of the membranes, measured for nitrogen Grade 4.8 under standard conditions as defined in the description, used in the feed stream separation stage, and the quotient of the pressure ratio over the permeate separation stage to the pressure ratio of the feed stream separation stage is in a range of from 0.5 to 8. a feed stream separation stage, a retentate separation stage and a permeate separation stage, and optionally a compressor arranged up-stream of the feed stream separation stage and/or at least one vacuum device arranged in at least one permeate stream of the feed stream separation stage, the retentate separation stage and/or the permeate separation stage, wherein the feed stream separation stage separates a feed stream comprising at least two components into a first permeate stream and a first retentate stream, and the retentate separation stage separates the first retentate stream into a second permeate stream and a second retentate stream, and the permeate separation stage separates the first permeate stream into a third retentate stream and a third permeate stream, and the second retentate stream is removed as a first product or further processed or optionally can be discarded if the third permeate stream is removed or further processed; and the third permeate stream is removed as product or further processed or optionally can be discarded if the second retentate stream is removed or further processed, and the second permeate stream and the third retentate stream are fed to the feed stream, and the first permeate stream is preferably not subjected to a recompression, and the feed stream separation stage, the retentate separation stage and the permeate separation stage are membrane separation stages, and the gas volume recycled in the second permeate stream and in the third retentate stream totals 60 to 100 % by volume of the crude gas stream, and the total capacity of the membranes, measured for nitrogen Grade 4.8 under standard conditions as defined in the description, used in the retentate separation stage is higher than the total capacity of the membranes, measured for nitrogen Grade 4.8 under standard conditions as defined in the description, used in the feed stream separation stage, and the quotient of the pressure ratio over the permeate separation stage to the pressure ratio of the feed stream separation stage is in a range of from 0.5 to 8.