Are Ionic Liquids Suitable for Suppressing Coal Spontaneous Combustion?

Fire-Prevention Characteristics of an Active Colloid Prepared from Stimulated Fly Ash Component

In this paper, an active colloid (AC) with a three-dimensional network framework, prepared from stimulated fly ash (FA) component by an acid-base compound chemical method, was proposed for prevention of coal mine fire. During the stimulation process, the active substance in fly ash can be released and transformed into effective components for fire prevention. Research results show that Al³⁺, Fe³⁺, and Ti⁴⁺ from FA can serve as metal cross-linking agents to graft-copolymerize with sodium carboxymethyl cellulose. Mg²⁺ and Ca²⁺ can be formed into halogenated salts that are encapsulated by composite colloids and cooperate with them to participate in fire prevention. The remaining fly ash solid particles served as an inert component can be fixed in the framework to encapsulate more water, improving the colloid's strength and water retention. The content of the active component was measured by inductively coupled plasma (ICP) emission spectroscopy to evaluate the stimulation effect of fly ash. The gel time, viscosity, water retention, and other performance parameters were determined for evaluation of physical characteristics. The fire-prevention performances of AC were also determined by the inhibition performance test, thermogravimetric analysis, and infrared spectroscopy. Moreover, the fire-prevention mechanism of AC was also explored. These results showed that the AC prepared from the stimulated fly ash component can greatly inhibit the spontaneous combustion of coal and can be chosen as a potential material for prevention of coal mine fire caused by spontaneous combustion of coal.