Some mining families resorted to scavenging for coal on slag heaps, a desperate move as most of the "slag" was very dangerous and liable to tip.
一些矿工家庭靠捡矿渣堆中的煤块解燃眉之急，这是一个绝望之举，因为大多数“矿渣”十分危险，极易倒塌。
2
In the closed seam, the pyrogenic rock compressed and compacted the structure coal. There is a stress concentrated at the tip of the structure, which could provide the inner energy for the gas.
火成岩对煤层挤压揉皱形成构造煤，同时构造尖灭端应力集中，提供了足够的瓦斯热力学能。
3
The formation of thin coal shell that is formed by aerofoil cracks engendered at the tip of primary cracks in the entry's surrounding coal is analysed.