Ferro silicon powder use and pulverization phenomenon

Ferro silicon powder is a ferro alloy composed of iron and silicon. During the storage and transportation of bulk ferro silicon, it will naturally become fine particles. People habitually call it "powdering phenomenon". This is a pretty serious quality problem. This is because ferro silicon which tends to pulverize is inconvenient to store and unfavorable to use after pulverization, and a flammable and poisonous gas will be produced during pulverization, which is likely to cause unsafe accidents such as poisoning and burning.

In recent years, 75% ferro silicon products have been powdered to varying degrees many times, most of which occurred around the Spring Festival and in July and August. Through the observation of the pulverized ferro silicon in the alloy library, it is found that the pulverization of ferro silicon mostly occurs in the middle and lower parts of the ingot and the structure with pores, and it first begins to pulverize from an obvious trace in the middle of the ingot, which leads to the ingot Cracking, loosening, until pulverization.

During the smelting process of ferro silicon, most of the oxides such as aluminum and phosphorus brought in by ore and coke are reduced under the action of high temperature, and some form aluminum phosphide, which is dissolved in the liquid alloy. When condensing, these low melting point Impurities remain on the grain boundaries. In addition, during the condensation process of the alloy, a phase change occurs inside to cause volume expansion to generate internal stress, which leads to many small cracks inside. When the alloy is stored and transported, the aluminum phosphide on the grain boundary of the alloy changes under the action of moisture in the air: 2AlP+H2O→Al2O3+2PH3. Therefore, the bulk alloy is turned into a powder. It can be seen that the pulverization of ferro silicon is due to the presence of aluminum phosphide impurities inside the alloy and the action of external humid air.