KRIEL COLLIERY MINES COAL FROM ABOVE AND BELOW.

The Witbank-Highveld coalfield is one of the most important in South Africa and covers a large portion of the southeastern Transvaal. Colliery was originally planned as an underground mine only. Production began in 1975, but as planning progressed the possibilities of surface mining were investigated. Three of the power station's six boilers were subsequently modified to accommodate the lower quality surface-mined coal. There is no preparation plant. All coal is crushed to 25 mm and transported direct to the power station silos. Underground, the No. 4 Seam is mined by room-and-pillar methods. The seam is horizontal and very consistent, and there are no water problems. A typical underground section will advance on 15 headings at a time. Fresh air enters the central roadways of the section and spreads out both ways along the face.