Superwall Mining System
In the January issue of Coal Leader Tony Sharkey wrote a response to the article Superwall Mining System which I wrote that had appeared in the December issue.
I would like to thank Mr. Sharkey for his interest and insight in The Superwall Mining System and will gladly discuss the issues in which he brought up.
Mr. Sharkey's first and primary concern was possible problems of longwall roof control at or near the face ends and rock slides and falls from the face of the highwall behind the face/highwall junction and immediately ahead of it. This area does deserve special attention but with proper engineering can be suitably dealt with. Rather than slope the highwall at a very shallow degree as Mr. Sharkey suggests. It would be better to design the highwall with a safety bench limiting the primary wall to around fifteen feet and having a safety bench between ten to twenty feet and sloping the next twenty feet or so above the safety bench to about seventy five degrees this would allow for a more manageable wall and keep a greater amount of cover over your endgate shields. I am including a rough sketch of a typical scenario although every sight would have to be dealt with independently depending on the geographical layout. I have discussed this layout with multiple industry experts including Dr. Syd Peng at West Virginia University and they agree that with access to the highwall using the described layout the highwall should prove to be manageable.
The next concern Mr. Sharkey had was that setting of the shields would destroy a wedge of the roof because of the setting pressures required to advance the ram. First we
would eliminated the wedge design of the roof by utilizing the bench design this combined with incremental pressure settings which is what Andreas Filipiak Senior Chief Engineer Plow Division DBT recommended should prevent the shields setting pressure from destroying the top while allowing enough force to advance the face conveyor.
Another concern was maintenance of a constant face length. Ideally it is desirable to select a face length that is most consistent with the topology of the projected area that allows for the surface contour cut to be economical. Also it would be best to run the face conveyor a little longer to allow for wider areas of the ridgeline while adding and removing shields by walking the face in and out. It would be better to minimize having to lengthen the face conveyor although with access from the surface and with the use of surface equipment more viable than in a normal underground longwall application still time consuming. It is also very possible to negotiate curves along a ridgeline. Every application would have to be closely calculated to determine the optimal face lengths and contour cuts for the best overall performance.
Next comes the concern that even though a positive issue that any coal operator would love to deal with but still an issue, much higher than normal coal output. It would be difficult to suggest the ideal coal haulage solution without knowing the details of the projected sight such as location from loadout or plant and possible mass stockpile area, etc, with all the mobile haulage equipment available today I'm sure a suitable solution could be resolved.
The other concern was ventilating the face; ventilation would be achieved by installing a fan in one of the specially designed mobile canopies at the gate ends or by means of a portable fan unit utilizing a flexible tubing to force air across the face with the lack of complicity adequate ventilation should prove to be easily accomplished. Recirculation of the fans air shouldn't be an issue.
Again, I would like to thank Mr. Sharkey for his interest in the Superwall Mining System and would like to encourage him or anyone else interested in learning more about the system to please contact either Jeff Harman at 276-880-1034 or Cell (276) 356-1700, or Email firstname.lastname@example.org or me (276) 597-2209, Cell (276) 356-1706, or
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