Preparation of phosphogypsum-based explosion suppressant to reduce the severity of dust explosions

This study utilizes industrial waste phosphogypsum (PG) leachate as the raw material to prepare a magnesium ammonium phosphate (MAP) powder suppressant through reaction system adjustment and coprecipitation reactions, achieving the recycling and reuse of waste materials. The impact of the MAP powder suppressant on the explosion of nitrile butadiene rubber (NBR) dust was investigated in a 20-L spherical explosion vessel and a 1.2-L Hartmann tube. The results indicated that MAP has significant suppression effect on NBR dust explosion. When 70 % MAP was added, the maximum explosion pressure (P_max) of NBR dust decreased from 4.8 to 1.55 bar, and the explosion index (K_St) dropped from 35.75 to 10.61 bar·m·s⁻¹. When 90 % MAP was added, the NBR dust explosion can be completely suppressed. Additionally, with the addition of 50 % MAP, the ignition time of NBR dust was delayed by 7 ms, the duration from the maximum flame moment of the dust explosion to complete flame extinction decreased from 515 to 306 ms, and both the flame brightness and flame area were also reduced. Thermal analysis research showed that the explosion suppression mechanism of MAP powder suppressant is mainly through physical and chemical aspects, including effects of physical barrier, endothermic cooling and consumption of free radicals.