The preparation of novel core–shell suppressor and its suppression mechanism on coal dust explosion flame

Abstract

To explore ways of further guaranteeing the production safety of coal processing, novel powder suppressors with core–shell structure were prepared through anti-solvent crystallization method by loading potassium oxalate (K) and ferric citrate (T) on treated waste molecular sieve. Flame propagation experiments were performed to investigate the effects of suppressors prepared under different conditions on coal dust flame propagation. The results showed that when K and T were added simultaneously at the loading of 30 wt%, the suppressor S@T-K showed best suppression performance. The pyrolysis-oxidation mechanism of coal dust with and without suppressor S@T-K was analyzed using Coats-Redfern (C-R) method. After the suppressor was added, the activation energy increased by 11.55 kJ/mol and 15.37 kJ/mol in the rapid and slow pyrolysis stages, respectively. The activation energy values of the coal sample with and without the suppressor under different conversion ratios were further calculated using Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. The average activation energy values during the rapid and slow pyrolysis stages both agree well with the C-R calculation, which verifies the appropriateness of using C-R method to identify the reaction mechanism. By combining the coal dust flame propagation behaviors with the pre- and post-explosion characterization results, it is proposed that waste molecular sieve composite powders with core–shell structure suppress flame propagation through the synergy of physical and chemical reactions.