Study on the stability of foamed gel and its structural evolution characteristics

Foamed gel is a kind of highly efficient coal spontaneous combustion control material, which combines the fluidity and accumulation of foam, high temperature resistance of the gel and other fire-fighting properties. This paper describes the formation principle, structural evolution, stability and fluidity of foamed gel. Foamed gel is mainly formed by foaming agent, crosslinking agent and water through physical foaming and gelling reaction, the formation process is divided into two stages, the first stage is physical foaming, forming foam solution. In the second stage, the crosslinking agent is added to the foam and the foamed gel is formed after the gelling reaction. The first stage, foamed gel mainly reflects the fluidity and accumulation of foam, the second stage, with the increase of colloidal amount, foamed gel reflects the temperature resistance of colloidal, at the same time, the gel formation time can be controlled by the amount of crosslinking agent. The basic structure of the foamed gel is the same as that of the water-based foam. The gel particles form the basic skeleton of the foamed gel, which slows down the gravity drainage and the disproportionation rate of the foam. The evolution process of foamed structure of gel includes liquid film rupture, gel formation and skeleton collapse, and finally gel layer filling coal fracture. The flow of foamed gel in goaf is affected by grouting pressure, gravity and resistance. The transverse flow velocity is greater than the longitudinal flow velocity, and the contour of the pre-diffusion peak is ellipsoid. The research results provide a strong support for the scientific application of foamed gel.