Preparation of a New Type of Iron-Based Polymer Hydrogel for Mining and Its Firefighting Performance

To address the issue of coal self-ignition in mining areas, a water-based gel was developed using carboxymethyl cellulose sodium (CMC), ferric citrate, and glucono-delta-lactone as raw materials. The gel's gelation time was found to be controllable, and the system viscosity exhibited a threshold between 2.5 and 3% CMC content. Compared to water, the gel showed improved thermal stability by 26-31% for different formulations. The addition of the gel reduced CO emissions from coal by 31.3% within the temperature range of 80-220 °C, and it also decreased the reactivity of functional groups in coal molecules, resulting in a 1.7-37.7% increase in coal's activation energy. In simulated fire extinguishing experiments, the gel effectively adhered to the surface of the coal seam, forming an oxygen isolation film, and significantly enhanced the cooling and extinguishing effect compared to water.