Approximately 40% of our coal is derived from opencast operations. Several of these opencast operations have recovery rates of nearly 90%. Coal lying less than 70 metres below the surface is extracted from a progressive series of parallel, long, narrow trenches. Overburden rock and soil lying above the coal seam is scraped and blasted out of the currently mined trench. It is then tipped into the mined void of the previous trench.
The stripping operation is carried out by having the draglines walked with large scraper buckets slung beneath long, crane-type boom arms. The exposed underlying coal seams are drilled and blasted loose and hauled out of the pit by heavy duty trucks. When the coal from all viable seams has been extracted and the spoil of the next parallel trench has been deposited in the void, the rehabilitation process begins. The overburden is flattened, the previously stored top soil is spread over it and the area is seeded with a mixture of grasses to return the landscape to its ecological balance.