Abstract: In order to study the fire risk of oil shale dust， an asymmetric model of dust layer ignition under steady-state condition was established by using chemical reaction kinetics， heat transfer and Thomas thermal ignition theory. The minimum ignition temperature of dust layer of 4 oil shale samples from the major producing areas of China was tested. The results showed that the minimum ignition temperature is between 503~613K， and it decreases with the increasing layer thickness. The minimum ignition temperature order of the four samples is as follows: Fushun> Huadian> Longkou> Maoming， which is correlated reciprocally with volatile content. Using the theory model， the activation energy and critical ignition temperature corresponding to different thickness were calculated. It was found that the error between the calculation critical ignition temperature and experimental results is within 10%， which provides a feasible method on theoretical prediction of fire risk in the oil shale production process.

Key words: oil shale, dust layer, hot plate test apparatus, ignition temperature, Thomas model