uhhhhh...I thought Methane emissions have dropped?
Didn’t they read the IPCC summary?
Well, one could do scrubbing, or absorbtive capture - if one were to ventilate the shaft forcefully, then either pass the air+methane over large charcoal beds or through a scrubber with naphtha oil- and then by reheating the oil or the charcoal [in a separate circuit] most of that methane could be released and caprured.
FYI:
The weight of the Earth’s atmosphere can be calculated as follows. Atmospheric pressure at sea level is on average 14.5 pounds per square inch = 10 tons per square metre. This pressure is due to the weight of atmosphere above an area at sea level of one square metre.
The radius of the Earth “r” is 5,925 km and so the surface area of the Earth (land and ocean) is 4 x “pie” x “r” squared = 4 x 3.142 x 5925 x 5925 = 441 million square kilometres = 441,000 billion square metres.
Therefore the weight of the Earth’s atmosphere is 441,000 billion x 10 = 4.41 million billion tons.
Methane has in the past been a big killer of miners. If capturing the methane in some way concentrates the methane somewhere in the mine it has a potential to increase risk to the miners.