Preparation and Performance Study of a Novel High Water Retention Gel for Inhibiting the Spontaneous Combustion of Coal

ABSTRACT To address the poor water retention and inadequate sealing of air‐leakage pathways in traditional mining hydrogel, a novel CPA gel was successfully synthesized using acrylamide (AM), polyethyleneimine (PEI), and calcium hydroxide (Ca(OH) 2 ) as raw materials. With water‐retention capacity as the orthogonal test evaluation index, and integrating thermal stability, rheological behavior, and plugging performance, the optimal formulation was determined to be 8% AM +0.06% MBA + 0.5% PEI. The gel formation mechanism, performance characterization, and inhibition characteristics were subsequently investigated. The results show that the synthesized gel develops a dense three‐dimensional network architecture, enhancing water retention capabilities that effectively immobilize water molecules under elevated temperatures and prolong endothermic time. Long‐term wetting of the coal body cools and lowers its temperature. The novel gel exhibits pronounced shear‐thinning rheological behavior and low pumping resistance. The gel sealing the coal surface showed no significant shrinkage, deformation, or bubble formation after 14 days, and formed a physical layer of oxygen isolation that prevents oxygen from reacting with the coal. The programmed temperature increase experiment indicates that the CPA‐3 gel‐treated coal sample demonstrated lower emissions of CO and C 2 H 4 gases compared to the other coal samples. At 100°C, the CO gas inhibition rate reached 68.49%. The activation energy increased by 20.02% in the first stage and 17.00% in the second stage. This gel can interrupt the chain reaction of coal oxidation, thereby suppressing the occurrence of coal spontaneous combustion. This study lays a theoretical foundation for the development of more efficient and sustainable fire prevention technologies and provides a basis for their practical application in goafs.