As we all know, iron sulfide is the general name of iron and sulfur compounds, mainly including ferrous disulfide, ferrous sulfide and ferrous trisulfide.
1. Ferrous disulfide: FeS2 is a yellow crystal, which is the main component of pyrite and has diamagnetism. The melting point of pyrite is 1171 ℃, the density is g / cm3, and it has a cubic lattice.
2. Ferrous sulfide: FES is brownish black block; Melting point 1193 ~ 1199 ℃, density g / cm3; Insoluble in water, soluble in acid aqueous solution, while producing hydrogen sulfide.
3. Iron trisulfide: fe2s3 is a yellow green solid; If the relative density is strong, it will decompose; Insoluble in water, it decomposes into ferrous sulfide and sulfur in hot water; In case of acid decomposition, hydrogen sulfide gas is released.
Therefore, when iron sulfide reaches spontaneous combustion, it is the chemical reaction of these compounds.
Iron sulfide is widely used in the treatment of heavy metal wastewater. Iron sulfide heptahydrate cannot be exposed to air and is easy to be oxidized, causing color changes. Iron sulfide pentahydrate means that the crystal contains five crystal waters, referred to as green alum for short, and its appearance is water green or blue-green. In addition to its different structure from iron sulfide heptahydrate, it has basically the same effect, has flocculation effect, and can also remove part of COD and decolorization in water. Iron sulfide monohydrate comes from iron sulfide heptahydrate by drying. Its appearance is white or light gray powder, with a general content of more than 95%. It has low moisture and strong stability.
Iron sulfide is widely used in water treatment, pharmaceutical industry, agriculture, analytical chemistry and other fields. It can also be used as reductant and colorant to adjust the pH of soil. It has strong adaptability to all kinds of water quality. It has better purification effect for pollutants, algae and high turbidity raw water. After treatment, the salt content in the water is particularly small. It is suitable for industrial sewage, urban sewage, industrial wastewater, domestic sewage and other industries.