Ferro Silicon Air humidity is too large
Why some ferrosilicon will occur powder phenomenon?
Some of the composition of ferrosilicon, sometimes due to storage during the water or air humidity is too large, while the aluminum, calcium and phosphorus impurities in the high, after a certain period of time, it will produce powder phenomenon, and then release the smell , Toxic phosphine (PH3) and hydrogen (ASH3) gas, serious even when the phenomenon may occur burning.
Ferromanganese in the aluminum, phosphorus and calcium content is not appropriate, will lead to ferrosilicon powder (shown in Figure 1). When the aluminum and phosphorus content at the same time increased to a certain value, the ferrosilicon in the humidity of the air is easy to produce powder. Some data pointed out that the phosphorus content of ferrosilicon is less than 0.04%, aluminum content of less than 3%, not easy to produce powder phenomenon.
Some units have the silicon content of ferrosilicon on the ferro-iron powder phenomenon was observed and studied. Preliminary view, ferrosilicon in the low silicon content (mostly waste) is often easy to powder. The reason may be due to ferrosilicon FeSi, FeSi2 and other silicon and iron compounds to reduce the volume of the temperature expansion, resulting in ferrosilicon powder. Aluminum content of ferrosilicon in the water after the formation of aluminum hydroxide and gas generation, is the main reason for the ferrosilicon powder.
The cooling rate after pouring also has an effect on the silicite pulverization. Ferrosilicon cooling speed, silicon, the smaller the degree of segregation, not easy to produce powder; cooling speed is slow, silicon segregation is large, it is easy to produce powder. The same token, the thickness of ferrosilicon ingots thick, easy to produce powder, thin when it is not easy to produce powder.
In order to prevent the production of ferrosilicon powder, should pay attention to the following three points:
1. The thickness of ferrosilicon ingots is not too thick to reduce the amount of silicon silicon containing the amount of segregation.
2. Strict control of the silicon content of ferrosilicon, not too low. Control of ferrosilicon aluminum, phosphorus and calcium content, for this purpose to use better raw materials, in particular, can not use high-ash coke to reduce the aluminum and phosphorus content, in order to reduce the calcium content of ferrosilicon, smelting should be reduced lime The
3. Ferrosilicon should be stored in the library, to prevent rain.