Effect factors for spontaneous combustion of iron sulfide in natural environment

Intrinsic factor leading to self-ignition of iron sulfide includes oxidizing and sending out heat in the atmosphere. External factor includes continuous oxygen supply and heat easily being accelerated. Oxidation experiments of iron sulfide were made in natural environment. The results show that iron sulfide has greater activity and natural oxidation tendency, which can react with oxygen in open system at room temperature and simultaneously result in releasing lots of heat. Effects of environment temperature, air speed, sulfuration time, exposed area and mass of FeS on spontaneous combustion were investigated using the same sulfides formed from Fe₂O₃. The results show that environment temperature has no significant influence on oxidation process of iron sulfide, air speed has double roles which can either promote or prevent development of self-ignition process and the heat-sending-out intensity of oxidation reaches the maximum when air speed is 1.5 m/s, the longer sulfuration time, the bigger exposed area together with more FeS can accelerate oxidation process and temperature rising, otherwise the spontaneous combustion tendency will be lessened.