LONG WALL MINING

But while politicians have been politicking, producers have been producing. In March of this year, Joy Mfg. Co, in Franklin, Pa., finished assembling the first complete longwall system manufactured in America and for the American mining market.

Longwalling almost completely mechanizes the coal mining process for many months at a time. The important part is the roofing. Supports (as shown on the next page) are placed along the 400 to 600 ft face of a coal seam. Under these supports (the type with the canopy shown in the figure is called a shield") a shearer with a couple of cutting drums chews into the coal face about a foot at a time, it runs along tracks below the face (perpendicular to the plane of the paper in the figure) and is remotely controlled by a single miner. As the lumps of coal fall from the wall, they are caught by a built in conveyor (running parallel to the tracks) and fed to a network of other conveyors that speed it to the surface.

A good longwall seam can be as long as a mile and keep the machine creeping forward three shifts a day for almost a year, producing up to 2,000 tons per day (the record, with 3 shifts of 11 men each, is 20,000 tons). As the roof supports, together with the tracks and conveyors, advance into the coal seem, the roof collapses behind them; only 15% of the coal is left behind.

As of this year, there are 80 longwall faces in operation in the US, with at least 5 suppliers of roof supports conveyors and shearers.

The advantage of longwalling is not just that it gets out 85% instead of 50% of the coal. It aIso produces about 4 times as much coal as the next most productive method continuous mining (in which the machine chews into the coal face forward, not sideways, under its own roof support and its attached conveyor belt running away from the coal face).

Longwalling is safer than other methods with respect to cave-ins, but thick coal dust remains a problem.

Opposition is likely to come not only from the usual eco-kiddies in Carter's anti energy administration, but also from the United Mine Workers' union, which did more than anybody else to make the high investment cost of longwalling economic when they struck to raise labor costs 39% over the next 3 years.

But the UMU leadership has never been very smart. They have just published an anti-nuclear pamphlet filled with slime extracted from Kendall's and Caldicott's gastric juices. What they have forgotten is that nuclear power has rarely had more effevtive support than that triggered by last winter's coal strike called by the UMW.

More: "Longwall becomes Americanized," Coal Mining & Processing, May 1978; "How to keep your longwall working," Coal Age, April 1978.