(Ph) 4. Mine Design
Access to the coal at Phalen Colliery was gained by driving five main slopes, downdip to the north, within the Phalen Seam. Longwall mining panels were developed, along strike, by driving roadways (east-west) from both sides of the access slopes. (Figure Ph4) Panels ranged from 900 to 3000 meters in length, and from 145 to 260 meters in width. A total of 14 panels operated during the life of Phalen Colliery; the last of these was 8 East. The pillars separating adjacent panels ranged from 100 to 70 meters in width.
The roadway drivage connecting the headgate and tailgate at the end of the panel is known as the longwall face. At Phalen, the longwall face is driven roughly in the direction of seam inclination. Seam dip at Phalen Colliery averages about 10 degrees (Figure Ph5).
The intersection of the wall face drivage with the top and bottom gates of a panel are roughly at a right angle. The width of the drivage must be sufficient to provide room for the installation of hydraulic roof support (2 leg shields); width is usually in the 6 to 7 meter range.
The largest exposures of roof at Phalen are normally encountered when crosscuts driven between the main access slopes intersect adjacent slopes at an acute angle.
Although continuous miners were used for driving development headings at Phalen, the practice of extended cuts was not used.