Synthesis and Characteristics of a pH-Sensitive Sol-Gel Transition Colloid for Coal Fire Extinguishing

Abstract

Coal fires, most of which are triggered by the spontaneous combustion of coal, cause a huge waste of resources and release poisonous and harmful substances into the environment, seriously threatening the safety of industrial production. Gel flame retardant plays a core role in coal fire prevention and extinguishing. Most gel flame retardants used in coal fires possess good sealing and oxygen isolation properties, but it is difficult for them to flow deep into fire areas due to their low fluidity. Some fire extinguishing agents with good fluidity lack leak-blocking performance. In order to simultaneously improve the fluidity, leakage sealing, and oxygen isolation effects of coal fire extinguishing colloids, a novel, pH-sensitive, sol-gel transition colloid was prepared using low methoxyl pectin (LMP), calcium bentonite (Ca-Bt), sodium bentonite (Na-Bt), and water as the main components. When the initial sol-state colloid absorbed acid gas products from coal combustion, the pH value decreased and a large amount of Ca2+ in Ca-Bt precipitated, thus immediately growing calcium bridges with LMP molecules that formed a three-dimensional network structure for gelation. The optimum ratio of the new colloid was determined through X-ray diffraction, tube inversion, shock shear-temperature scanning, and genetic algorithm. By testing the fire extinguishing performance of the colloid, the findings proved that the product had good oxygen isolation performance, strong adhesion ability, high thermal stability, and strong inhibition effects on coal combustion.

Study on the Inhibition Characteristics of Coal Spontaneous Combustion by Silica Gel Foam

“…The foam component mostly belongs to the surfactant component, which could improve the wetting of the gas–liquid interface between water and coal. Additionally, the foam component could enhance the fluidity of the gel system, thus balancing the overall performance of the new material Antioxidant inhibitor components: Antioxidants are known to scavenge free radicals, and the main function of the antioxidant component is to suppress the spontaneous combustion process of coal–oxygen, use chemical inhibitors to directly cut off the chain chemical reaction of coal–oxygen, reduce the chemical reaction heat, directly block the coal–oxygen reaction, and improve inhibition efficiency …”

“…The foam component mostly belongs to the surfactant component, which could improve the wetting of the gas–liquid interface between water and coal. Additionally, the foam component could enhance the fluidity of the gel system, thus balancing the overall performance of the new material …”

“…Additionally, the foam component could enhance the fluidity of the gel system, thus balancing the overall performance of the new material. 27 …”

Spatiotemporal Evolution and Frontier Focus Analysis Based on Coal Fire Control Body of Knowledge

“…These include slurries, foams, inert gases, colloids, and retardants [8][9][10][11][12][13][14][15][16]. Inhibition technology can be divided into the following three basic categories according to their principle of action: physical inhibition, chemical inhibition, and physicochemical synergistic inhibition with both characteristics [17][18][19][20][21][22][23][24][25][26][27][28]. The physical inhibition method is mainly to slow down the occurrence of coal oxygen reaction by endothermic cooling, isolating oxygen, and covering the surface active center of coal.…”