Because the firstcaving of work face haven't been finished, the tunnel roof and hole can not be used and gas often goes beyond the limit, so some measures must be taken.
It was the first time that full-mechanized caving mining was used under sea in the history of coal mining under sea in the world.
海域下煤层采用综放开采在世界海域煤炭开采史上还是首次。
3
As the first successful introduction of natural caving method in domestic nonferrous metal mine, Tongkuangyu mine increases production capacity and reduces production costs.