Sulfur, hydrogen sulfide and organic sulfur compounds are contained in the products or semi products of the chemical containers, such as coal gas, tar production, recovery of coking plant, refined benzene etc.. When these sulfur compounds on the vessel wall of iron and iron oxide long-term corrosion, will generate iron sulfide (Fe2Ss). Iron sulfide, a dark brown or black mass with metallic luster, can spontaneously ignite when exposed to oxygen in the air. It is easier to ignite when exposed to air. The ignition point of the iron sulfide is about 40.
　　Facts have proved that when the production of iron sulfide in gas production and other chemical containers, if the container is full of material, iron sulfide is impossible with the air of oxygen contact combustion, only when the liquid level in the tank is decreased and the maintenance of the container material emptying, iron sulfide will be exposed and in contact with the oxygen in the air, when the exposed surface of the iron sulfide oil or water evaporation after spontaneous combustion will occur. Once there is a flammable gas or vapor in the container and the formation of an explosive mixture of air, it will cause an explosion and fire.
　　Spontaneous combustion prevention of iron sulfide, must accomplish the following several points: one is the container when in use, the operator should be strictly in accordance with the procedures, constantly keep container within the normal level; the second is when the container to temporarily stop production, and the material and released, to prevent iron sulfide exposure, the best in a container filled with inert gas; the third is the maintenance vessel, should be in the material released in a timely manner to the inner wall of the container of watering repeatedly wet, avoid and exposed to the air and lead to iron sulfide spontaneous combustion; four is from the container cleaning sediment iron sulfide, should be properly disposed of, can not be dumped in flammable explosive place, to prevent iron sulfide spontaneous combustion caused by combustion and explosion accident. Five is the container for a period of time, it is best to smear on the inner wall of a layer of anti-corrosion material, so that can prevent the formation of iron sulfide, to prevent the occurrence of explosion accident.