Study on the mechanism of ammonium octamolybdate-modified grouting filling slurry in inhibiting coal spontaneous combustion
WU Rui
QIU Weiping
GUO Zhiguo
LIU Xiangyu
Abstract：To address the challenge of coal mine goaf reignition caused by high-temperature crack-ing and low flame-retardant efficiency in traditional coal gangue slurry,this study introduces ammo-nium octamolybdate(AMM),a highly effective flame-retardant and smoke-suppressing agent,into the coal gangue slurry system.The aim is to elucidate the mechanism by which AMM-modified slurry inhibits coal spontaneous combustion.Through grouting backfill fire prevention and extinguishing test systems,the macroscopic combustion characteristics of raw coal,blank grouted coal,magnesium chloride(MAG),and AMM-modified grouted coal were compared during oxida-tion at 30-270℃.Electron spin resonance and Fourier transform infrared spectroscopy were em-ployed to analyze changes in free radical types,concentrations,and surface functional groups in coal before and after AMM addition.Results indicate:Compared to 7％MAG-modified slurry,5％AMM-modified slurry reduces peak CO release concentration by 19.97％,exhibiting an inhibi-tion rate 11.78％higher than MAG.After slurry treatment,raw coal showed lower g-values,line widths,and radical concentrations during oxidation,demonstrating stronger self-ignition suppres-sion by AMM-modified slurry than MAG-modified slurry.Quantitative analysis of active functional group changes during oxidation revealed that AMM addition reduced oxygen-containing functional groups(-OH,-C=O)in coal molecules,inhibited internal methyl side-chain cleavage,and pro-moted formation of more stable ether bonds.Based on experimental results,it is inferred that dur-ing coal oxidation,AMM thermally decomposes to form MoO3,promoting intermolecular cross-linking reactions to create a protective carbon layer.This blocks the further generation of oxygen-containing radicals into R-OH,instead forming more stable compound structures.Consequently,the production of combustible CO gas is reduced,inhibiting coal spontaneous combustion from a physicochemical perspective.This achieves the enhanced fire prevention and extinguishing effect of AMM-modified coal gangue slurry.
Keywords：retardantammonium octamolybdatecoal gangue slurrygrouting and fillingcoal spontaneous combustionfire prevention and suppression
Publication Date：2026-03-31
Online Publishing Date：2026-04-08(First online date of this platform, not the publication date of the document)
Pages：12( 514-525 )