Why Do Some Ferrosilicon Break into Pieces?

What is ferrosilicon pulverization

Ferrosilicon, sometimes due to water or excessive air humidity during storage, as well as high content of aluminum, calcium and phosphorus impurities, will break into pieces after a certain period of time, and then emit foul-smelling, toxic phosphine (PH3) and hydrogen sulfide (ASH3) gases, and may even burn in severe cases.

Causes of ferrosilicon pulverization

1. Improper aluminum, phosphorus and calcium content in ferrosilicon will lead to ferrosilicon pulverization. When the content of aluminum and phosphorus increases to a certain value at the same time, this ferrosilicon is easily dissolved in high-humidity air and pulverizes. Some data indicate that when the phosphorus content in ferrosilicon is less than 0.04% and the aluminum content is less than 3%, ferrosilicon is not easy to pulverize.

2. Some personnel have observed and studied the silicon content of ferrosilicon and the pulverization phenomenon of ferrosilicon. It is preliminarily believed that the silicon content in ferrosilicon is low and it is often easy to pulverize. The reason may be that the volume expansion of silicon and iron compounds such as ferrosilicon, FeSi and FeSi2 decreases at the medium temperature, resulting in ferrosilicon pulverization. When aluminum-containing ferrosilicon meets water, it will form aluminum hydroxide and gas, which is the main reason for ferrosilicon pulverization.

3. The cooling speed after pouring also affects the pulverization of ferrosilicon. Ferrosilicon cools quickly and has a small silicon segregation, so it is not easy to pulverize; it cools slowly and has a large silicon segregation, so it is easy to pulverize. Similarly, if the thickness of the ferrosilicon ingot is thicker, it is easy to pulverize, but when it is thinner, it is not easy to pulverize.