A mining method-caving mining with filamentary hole and bottom column is introduced,which is suitable for the mines that are of low pitch,middle thickness,low value and unstable bottom rock property.是什么意思_A mining method-caving mining with filamentary hole and bottom column is introduced,which is suitable for the mines that are of low pitch,middle thickness,low value and unstable bottom rock property.在线翻译_英语_读音_用法_例句