A Theoretical Analysis of Spontaneous Combustion Micro-circulation in Loose Coal at the Top-Coal Caving Region of a Coal Drift

Micro-circulation at the top of a coal caving region was studied by in-situ temperature measurements,sampling,laboratory analysis and numerical simulation.Models of the flow and temperature fields show that broken coals near the top of the caving region can be divided into three zones.These are: A zone most likely to see spontaneous combustion,Ⅰ;A zone where spontaneous combustion is possible,Ⅱ,and;A zone affected by spontaneous combustion,Ⅲ.The mechanism of spontaneous combustion involves a balance of oxygen supply,from leakage,and consumption by oxidation.Heat flows also balance,heat flowing from the area to cooler zones while being produced locally by the oxidation process.Self-ignition occurs if leakage oxygen and heat production occur to a sufficiently great extent.Effective fire prevention can be seen to entail filling,plugging and interting at the top of the coal caving region.