Medium and small coal mines in north of Shaanxi Province generally adopt longwall remaining coal pillars support mining. 摘要長(cháng)壁留煤柱支撐法開(kāi)采是陜北中小煤礦普遍采用的一種采煤方法。
Many small and medium-sized coal mine production safety is still not solve the problem, this issue must not be the existence of trusting to luck, said Zhou Dadi. 許多中小煤礦仍然不能解決安全生產(chǎn)問(wèn)題，在此問(wèn)題上絕不能存在僥幸心理，周大地說(shuō)。
