Novel PFA-Based Inorganic Three-Phase Foam for Inhibiting Coal Spontaneous Combustion

Abstract

Fire accidents caused by coal spontaneous combustion usually lead to a large loss of coal resources and casualties. Not only that, the greenhouse effect is polluted while the environment is polluted. At present, the commonly used fire-extinguishing materials such as water, inhibitors, and organic foams have the disadvantages of poor stability and short fire-extinguishing cycles. It is difficult to effectively suppress coal spontaneous combustion and quickly extinguish the fire for a long time. To suppress the spontaneous combustion of coal, the research team proposed an inorganic three-phase foam with a high foam expansion rate, good cohesiveness, and excellent stability. In the formulation, pulverized fly ash (PFA) is used as the matrix, sodium dodecyl benzene sulfonate (SDBS) and α-olefin sulfonate (AOS) are used as foaming agents, curdlan is used as the foam stabilizer, and sodium silicate is the binder. The compound foaming agent with the best performance is optimized, through the two-group compounding test. The composite foaming agent’s optimal compound ratio is SDBS/AOS (3:2). The optimal ratio of inorganic three-phase foam (ITPF) components was obtained through the control variable method experiment. The water–cement ratio is 5:1, the composite foaming agent is 0.2%, the curdlan is 0.5%, and the sodium silicate is 1.6%. In addition, it has been determined by experiments that ITPF has the strongest foaming ability when the pH value is 9 and the temperature is 60 °C. The fire-extinguishing performance of the new material ITPF was investigated by thermogravimetry and coal spontaneous combustion tendency test. It has been observed that the new material has the effect of cooling down and isolating coal from contact with oxygen. The results show that the new material ITPF has the potential to prevent coal spontaneous combustion.

Detection of Spontaneous Combustion Areas of Coal Gangue Dumps and Comprehensive Governance Technologies: A Case Study

“…Through theoretical calculation and numerical simulation verification, the effective diffusion radius of the three-phase foam is determined to be 3m. 39 During the field preparation process, the coverage of the three-phase foam can be enhanced by adjusting the proportion of water and soil in the solid phase, which reduces the viscosity of the slurry. However, to ensure complete detection and control of the fire area without any uncovered spots, the design is still based on a minimum diffusion radius of 3m.…”

Research Progress of Gel Foam Extinguishing Agent in Coal Mines

“…Gel foams contain gelling and cross-linking agents, which will form a three-dimensional network structure to cover the surface of the coal body after a chemical reaction. When the moisture disappears completely, a gel film is formed, blocking oxygen from coming into contact with the coal [58,59].…”

Research on the Law of Coal Pillar Spontaneous Combustion and Fire Prevention and Control Technology

“…In the treatment of mine fire, techniques such as yellow mud injection, inert gas injection, and loess covering are generally adopted. − With the development of science and technology, mine fire prevention and control technology continue to progress. Such as three-phase foam as the representative of the foam class fire prevention materials, as well as the colloid as the representative of the colloid fire prevention materials gradually into the field of vision, the field application effect is remarkable. , Regarding research on coal pillars, most scholars at home and abroad focus on the mechanical characteristics and fragmentation mechanism of coal pillars. − However, it is worth noting that coal pillar cracks, under the influence of underground formation pressure, would further develop and result in a large number of air leakage channels. Besides, air circulation caused by the atmospheric pressure difference on both sides of coal pillars may also accelerate the spontaneous combustion of fragmented coal in coal pillars. , Under the guidance of safety-related coefficient criteria and safety principles, Tang divided the narrow coal pillar and the goaf into “safe zone”, “general zone”, and “dangerous zone”, according to two indicators, i.e., the permeability of the narrow coal pillar and the spontaneous combustion risk of residual coal in the goaf .…”

“…Such as three-phase foam as the representative of the foam class fire prevention materials, as well as the colloid as the representative of the colloid fire prevention materials gradually into the field of vision, the field application effect is remarkable. 14 , 15 Regarding research on coal pillars, most scholars at home and abroad focus on the mechanical characteristics and fragmentation mechanism of coal pillars. 16 − 19 However, it is worth noting that coal pillar cracks, under the influence of underground formation pressure, would further develop and result in a large number of air leakage channels.…”