Ferro silicon 72 and ferro silicon 75 are two different grades of ferro silicon alloy that have different silicon content.

Ferro silicon 72 typically contains around 72% silicon, with the remainder being iron, aluminum, and other trace elements. Ferro silicon 75, on the other hand, contains around 75% silicon.

The higher silicon content in ferro silicon 75 means that it is generally more expensive than ferro silicon 72. However, it also provides some benefits in terms of its performance. For example, ferro silicon 75 can provide a greater reduction in the oxygen content of molten steel, resulting in improved steel quality. Additionally, ferro silicon 75 can have a slightly lower melting point than ferro silicon 72, which can make it easier to work with in certain applications.

The choice of which grade of ferro silicon to use depends on the specific requirements of the steel-making or casting process. In general, if a higher degree of deoxidization is required, ferro silicon 75 may be the better choice. If cost is a primary concern, ferro silicon 72 may be more suitable. It is best to consult with a metallurgist or materials engineer to determine which grade of ferro silicon would be best for a particular application.