Study of the Penetration and Diffusion Characteristics of Inorganic Solidified Foam in Rock Fractures

Abstract

To explore the penetration and diffusion law in coal and rock fractures when inorganic solidified foam (ISF) is used to prevent coal fire, the penetration experiment was conducted; the results showed that the penetration pressure fluctuates within a certain range and decreases with the diffusion distance. In the plane, the diffusion pattern presents an ellipsoid shape, and the diffusion area becomes increasingly large over time; in the plane, the foam fluid penetration changes from dense to loose in the direction and it does not undergo downward penetration and diffuses via its own weight in the direction; in the plane, it is loose on the left and dense on the right. The viscosity of ISF was tested and then the time-varying formula was fitted. The formula of the effective diffusion radius for foam fluid diffusing in the fracture channel was determined theoretically. The permeability coefficient and other related parameters were calculated in terms of the penetration pressure and diffusion time of two monitoring points. At last, the prediction formula of effective diffusion distance of foam fluid was verified with the remaining seven monitoring points and all the relative error of monitoring is within 10%.

Delineation and Prevention of the Spontaneous Combustion Dangerous Area of Coal in a Regenerated Roof: A Case Study in the Zhoujing Coal Mine, China

“…In view of the coal spontaneous combustion, the presently applied fire prevention and control technologies include grouting into the goaf, − inert gas injection, spraying composite inhibitor, composite gel injection, , liquid nitrogen injection, − and injection of colloidal material. − However, there were some disadvantages for these traditional technologies because of their short effective duration, weak stacking ability, poor fluidity, and high cost. − Therefore, foam technology was proposed to inhibit spontaneous combustion of coal in goaf areas as a result of its superior advantages, e.g., low density, excellent transportation performance in the pipeline, and excellent ability to spread and stack. − In the field of extinguishing fires, aqueous foam has been widely used to extinguish methanol pool fires, forest fires, and coal fires. − However, traditional aqueous foam was always unsatisfactory as a result of its quick drainage and weak stability. Especially for the foam used to inhibit spontaneous combustion of coal, it did not have long-term effectiveness to retard the oxidation of coal.…”