Inhibition performance of microcapsule material on coal oxidation

The frequent occurrence of coal spontaneous combustion (CSC) poses a serious threat to coal mine production safety. Inhibitor fire extinguishing technology has therefore played an important role in reducing CSC in recent years. Microcapsule material is a combined fire extinguishing material that has shown a good effect in preventing CSC. In this study, microcapsule materials were fabricated with short-chain ammonium polyphosphate as the core material and melamine–formaldehyde resin as the capsule material. The microcapsule materials were uniformly mixed with coal samples according to mass ratios of 1:4, 1:5, and 1:6. The quality change of the microcapsule material during heating was detected from thermogravimetric experiments. The results show that microcapsule material decomposition can be divided into five stages. The ammonium polyphosphate begins to decompose at 151.1 °C and the decomposition rate of the microcapsule material reaches a maximum at 200 °C Fourier transform infrared spectroscopy was used to detect the distribution of functional groups during coal oxidation before and after the addition of different microcapsule ratios. The results show that microcapsule materials can reduce the number of hydroxyl and aliphatic hydrocarbons in coal and enhance the stability of aromatic hydrocarbons and oxygenic functional groups. We also performed synchronous thermal analyzer experiments to monitor the temperatures of each characteristic point in the coal oxidation and heating process. The results show that the microcapsule material can reduce the coal mass loss rate, delay the temperature of heat equilibrium by around 100 °C reduce the heat release by more than 4560 J g–1, and increase the maximum temperature of the heat release rate by at least 14 °C. These materials therefore effectively reduce the coal-oxygen composite reaction rate and delay the CSC process.