Consol's record production runs give impetus to use of shield supports for U. S. longwalls

Although shield support systems for longwall mining have been used abroad for many years, it is only recently (1975) that they have been introduced into U.S. coal mines. These units are described and their advantages discussed. The capital cost is high, but they do permit a high productivity, permit recovery of 90 to 95 percent of the coal (compared to about 50 percent for the continuous room-and-pillar method), simplify ventilation, reduce roof support needed and provide greater safety. Various types of shield support are described. Finally, methods and problems of moving the shields to a new panel are discussed. (LTN)