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In German underground hard coal mining，extraction has had to be moved to ever-greater depths，
using the multi-seam mining method.On the one hand this requires high quality longwall entries，which are normally used twice.On the other hand successful control of gas emissions is a
decisive factor if longwall mining is to be productive.Despite extremely difficult geological
conditions with winning depths of more than 1，100 m，rock temperatures of over 60℃ and
releasable gas contents in the working seams up to 9 m3/t coal and in the surrounding strata
(for 1 ton saleable coal)up to 40 m3/t,it has been possible to implement high-performance
longwall mining operations.Several factors are important for this success today and in the
future：a program for advance calculation of gas emissions developed on the basis of practical
experience，modern gas drainage and monitoring technology，supporting and sealing off the seam
edge areas using innovative construction material machinery-and last but not least，a carefully trained and experienced mining team.