Controlling factors of spontaneous combustion of coal seams in the Wuda coalfield, western Inner Mongolia, China

Spontaneous combustion of coal seams is a complicated physical-chemical and environmental process and the result of integrated action of many kinds of internal causes and external conditions. The paper analyzes the internal causes and external conditions of spontaneous combustion and reveals various controlling factors in the Wuda coalfield, Inner Mongolia. The internal causes include the coal seam thickness and metamorphic grade, ash content, caloric value, sulfur content and maceral content; the external conditions include geological structure, climate, hydrogeology, topography and landforms, mode of occurrence of coal seams and mining of large mines and small coal pits. Finally, the paper discusses different prevention and control methods for spontaneous combustion of coals of different origins, which provides a theoretical basis for studying and controlling coal fire in the future.