extremely thick coal seam

• 特厚煤层

extremely thick coal seam的用法和样例：

例句

1. Introduced the prevention methods and practice experience for the sixth pit in Xingshang Coal Mine adopted longwall inclined slicing experence mining method.
   介绍了兴山矿六井采用倾斜分层走向长壁采煤法开采特厚煤层，防治自然发火的经验。