Spontaneous Fires in Oil Shale Deposits: From Hazards to Resources

摘要

Spontaneous combustion of coal and oil shale compounds is a serious problem for many mining districts leading to significant safety and environmental challenges. As some slag heaps resulting from industries such as coal or oil shale production can contain a relatively high proportion of hydrocarbons, they can commence spontaneous subterranean combustion, which can be followed by surface fires and change the surrounding rock. Spontaneous combustion occurs due to high oil shale content (up to 6%) in limestone waste rock and overly large spoil heaps. Such fires can follow slow combustion of residual hydrocarbons. Spontaneous combustion has long been recognized as a fire hazard in stored oil shale. Heat generated by the oxidation then initiated the fire that may produce copious amounts of methane and carbon monoxide gases. Their extinction can require complete encasement, which can prove impossible for technical and financial reasons. Sprinkling is generally ineffective and injecting water under pressure counter-productive, because it carries oxygen, bringing the risk of explosion. This problem can be solved by special design of the oil shale refuse mass and management of heating process. The proposed technology includes the following steps (1) Refuse sorting; (2) Site configuration; (3) Cover system design; (4) Injection system for air; (5) Water pipelines for heating; (6) Operational constraints. Optimal construction and management of refuse deposits can transform these sites from hazardous into useful.