Coal dust explosion constitutes an ever-present hazard in underground coal mines worldwide. This study examines the effects of important parameters, such as, dust particle size, dust concentration and dust-dispersion-air pressure on rock dust inertant requirement for suppressing coal dust explosion using a Godbert-Greenwald (GG) furnace. It also elucidates the underlying mechanism involved in the coal dust explosion and its propagation. The study revealed that the proportion of rock dust required to inert the coal dust explosion increases with the decrease in the coal dust size and increase in the rock dust size. The finest size coal dust (<38 mu m) and the coarsest mine size coal dust (<850 mu m) required 90% and 72% rock dust inertant respectively for suppressing the coal dust explosion. The optimal coal dust concentration that causes a violent explosion and requires maximum proportion of rock dust inertant for explosion suppression was determined to be 427 g/m(3). The inertant requirement increased with the increase in dust-dispersion-air pressure up to 62 kPa. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.