Modeling temperature distribution upon liquid-nitrogen injection into a self heating coal mine goaf

•Both field test and simulation show occurrence of coal oxidation in workface #3418.•Injection of liquid N2 forms a cooling zone suppressing coal oxidation.•Injection of N2 reduces maximum goaf temperature preventing spontaneous combustion.•Cooling zone and effectiveness are strongly affected by injection location and rate. Liquid N2 could be injected into goaf to decrease temperature and prevent spontaneous combustion during mining. A working face at Liangbaosi coal mine was adopted for study. Firstly, a mathematical model for calculating the temperature field in goaf was developed and field tests without injection of liquid N2 were conducted to validate the model. Comparable development trends and hot zones between the simulation and field measurements were found. The hot zones were located about 35–45 m behind the workface on the air-return and air-intake sides in the goaf. Then the model was employed to simulate the time development of temperature distribution in the goaf with injection of liquid N2 from different locations. It was observed that a low-temperature cooling zone (