Self-Sustained Smoldering Combustion of a Coal-Waste Heap in Central Scotland

The landscape of Central Scotland, as well as that of England, is dotted with spoil heaps that remain from the coal mining industry that thrived in the region from the late 18th to the mid 20th centuries. Known in Scotland as “bings,” these spoil heaps consist of carbonaceous shales, siltstones, and coal fines that were separated from usable coal at the pit head, together with rock removed during excavation of the shaft and tunnels. There are as many as 560 bings in central Scotland (Scottish National Heritage, 2000), although many have been removed or remediated. Because of their high carbon content and porosity, bing materials are susceptible to smoldering combustion (Rein, 2009) that can be initiated from either an external ignition source (accidental or otherwise) or by self-heating (Drysdale, 2011). Combustion turns the waste material, which originally has a dark, blue-gray appearance, to a solid residue of bright red “blaes” and white ash. The blaes residue is a useful building-fill material.