Iron desiliconization is the process of removing silicon from iron, which is an important step in iron smelting. Iron desiliconization must be done before dephosphorization, which is the process of removing phosphorus from iron. Iron and silicon are closely related in many ways, so carefully removing the silicon is necessary before achieving a desiliconized state.
The process of iron desiliconization often involves the use of a low temperature regeneration slag that has low levels of silicon, for instance, by adding limestone, magnesia, and other agents of a certain proportion. This process is carried out by heating the slag to a specific temperature and evenly mixing the heated slag and iron silicon in the arc-furnace. By adding different proportions of slag agent into the arc-furnace, a floating layer is generated at the top, which is composed of a liquid slag and a pool sediment, while the bottom layer is harden and the composition of iron silicon remains unchanged; when heated, the floating layer will be melted and the pool sediment will be coagulated. The coagulated matter is composed of a significant amount of silicon and some impurities, and forms the slag component of the regenerative slag system.
The molten material will combine with the generated slag to form a floating liquid layer at the top and a slag sediment layer at the bottom. These two layers will move from one side of the arc-furnace to the other side, due to the electric current. The slag component will move to the side of the arc-furnace with a high electric current, whereas the iron silicon component should move to the low electric current side.
Nowadays, the technology of iron desiliconization has developed significantly. One of the most advanced technology is the oxygen-blown method. This method sees the furnace atmosphere temporarily replace with an oxygen containing gas, usually pure oxygen. This increases the burning rate of the slag component and eliminates the material with low impurity or a high concentration of silicon and other pollutants, in order to achieve a purified layer.
Furthermore, modern electric arc furnace technologies achieve a fast desiliconization rate, higher quality of steel, and higher steel yields. In such electric furnaces, the slag component will float to the top and collect, while the heavier iron silicon component remains at the bottom. This allows for a rapid advancement of the desiliconization process.
In summary, iron desiliconization is the process of removing silicon from iron by adding low temperature regeneration slag. In the modern day, the oxygen-blown method and electric arc furnace technology are two of the most advanced methods of iron desiliconization. These technologies allow for a faster desiliconization rate, higher quality steel, and higher steel yields.
