A coal mining method with a combination of a slicing and caving, a double benefit in control of water conducted crack zone development and in reductionof coal production cost can be obtained.
对厚煤层采用分层与放顶煤相结合的采煤方法,既可控制导水裂缝带的发育高度,又可降低生产成本。
2
Through the analysis of material and construction, the dissimilar steel gear is successfully welded using stress reductionzone by heating and proper assemble and welding sequence.