The risk of coal dust fire and explosion is a major safety concern in underground coal mines. A better understanding of the coal dust thermal properties which drive the fire and explosion phenomena would greatly assist in adopting an appropriate and effective protection approach to avoid such fires and explosions.
The aim of this work is to address the thermal and explosion characteristics of coal dust, such as minimum ignition energy (MIE), minimum ignition temperature (MIT) and minimum explosive concentration (MEC). Each of these parameters are considered to be the minimum requirement to initiate the combustion process. The heat release rate and burning behaviour of the coal dust samples are also examined in detail.
The experimental work was conducted on two typical coal dust samples (Samples A represent the run of mine coal dust and B represent a fine coal dust collected before the washing process) collected from an underground coal mine in the Hunter Valley region of Australia. The thermal and explosive characteristics of the coal dusts were examined by employing a variety of relevant apparatus such as cone calorimeter, hot plate furnace, Hartman glass tube and 20 L explosion chamber.
The results of this study indicated a significant discrepancy between the fire and explosion characteristics of these two samples. The differences in fire and explosion properties examined are related to the thermo-physical and chemical properties of the coal dust samples.
The dust layer MIT of Sample A was 270 C, which is lower than the dust layer MIT for Sample B by about 110 C. Moreover, Sample A required only 251 mJ to ignite, whereas Sample B required 740 mJ. Both Sample A and Sample B exploded using 1 kJ of ignition energy, however, the maximum pressure rise was achieved at 450 g.m-3. The heat release rate (HRR) experiments for coal dust samples, exposed to 50 kWm-2 heat flux, showed that the peak heat release rate for Sample A was 93.1 kWm-2 and 83.1 kWm-2 for Sample B. The oxidation reaction consumed 63.2 g and 76.0 g of oxygen during the combustion of samples A and B, respectively.
CITATION:Al-Zuraiji, M J A, Zanganeh, J and Moghtaderi, B, 2019. Investigation of combustion properties and burning behaviour of Australian Hunter Valley coal dust, in Proceedings Australian Mine Ventilation Conference 2019, pp 147159 (The Australasian Institute of Mining and Metallurgy: Melbourne).