The sublevel caving method is used in No.4 ore body of Fusan Iron Mine

and large scale stratum movement took place there for four times in the past a few years. Many kinds of instruments

such as AE monitor

convergence meter

etc.

are used to study the law of stratum pressure appearance. On this basis

oblique stopping lines and proper support system are adopted

so that the stratum movement is controlled

and continuous production of iron ore is realized with an extraction rate of eighty two per cent.