Preparation of Mg-Al hydrotalcite foam retardant and its inhibition characteristics study

In order to prevent coal spontaneous combustion, Mg-Al hydrotalcite foam with high stability and good flame retardant effect was prepared by using surfactant, foam stabilizer and Mg-Al hydrotalcite(HT) in a certain proportion. The optimum formula of Mg-Al hydrotalcite foam was determined by orthogonal test and Waring-Blender method. The inhibition characteristics were tested by temperature programmed device and cone calorimeter test. The results show that when the mass fraction of surfactant Silok8022 is 0.03%, the mass fraction of AOS is 0.1%, the mass fraction of LAMC is 0.075%, the mass fraction of foam stabilizer HEC is 0.05%, the mass fraction of flame retardant HT is 1%, the performance of Mg-Al hydrotalcite foam is the best. In terms of low temperature inhibition, the inhibition rate of HT foam reached 68.4%, and the CO volume fraction of coal samples added with HT foam at 200 °C was 36.9% lower than that of raw coal. In terms of high temperature combustion, the peak heat release rate of coal samples treated with HT foam decreased from 74.59 kW/m² to 43.48 kW/m², and the total heat release decreased from 9.98 MJ/m² to 7.15 MJ/m². Compared with MgCl₂ and AFFF, HT foam showed excellent flame retardant effect on coal. It was found that the content of aliphatic hydrocarbons and oxygen-containing functional groups in coal samples with HT foam was significantly reduced, indicating that HT foam had a strong inhibitory effect on coal spontaneous combustion.