Study on Slag Composite High‐Efficiency Fire Extinguishing Material and Its Characteristics of Coal Spontaneous Combustion Retardation

ABSTRACT This paper investigated a slag composite high‐efficiency fire extinguishing material to recycle power plant slag waste and apply it to prevent and control spontaneous coal combustion fires. The composite uses power plant slag as a base material, sodium carboxymethyl cellulose (CMC) as a polymer, and AlCit solution formulated with polyaluminum chloride and citric acid as a cross‐linking agent. X‐ray diffractometer (XRD) and scanning electron microscope (SEM) were used to analyze slag composition and morphology. Experiments investigated the effects of composites on coal microactive groups, rheological properties, and inhibition characteristics against coal spontaneous combustion. Analyses showed composites could effectively reduce activities of aromatic hydrocarbons, OH groups, aliphatic hydrocarbons, and oxygenated functional groups in coal samples, with prominent inhibition of oxygenated functional groups and OH reactive groups. Experimental results showed composite samples exhibited a shear thinning phenomenon of yield‐pseudoplastic fluid, and viscosity gradually increased with time. Viscosity increase rates of samples were 9.20%, 17.35%, and 30.75% for each 5‐min interval. Composites could delay the time when coal samples enter the rapid oxidation stage, and the crossing point temperature of coal samples increased from 152°C to 180°C. Composites had an inhibitory effect on coal oxygen reaction, and in programmed warming experiments, the temperature at which the residual mass of coal samples began to increase increased from 179°C to 202°C. The slag composite high‐efficiency fire extinguishing material provides reference value for the combination of slag waste and mine fire extinguishing technology.