The production process of low-alumina ferrosilicon powder uses a composite slag agent composed of iron concentrate powder, silicon powder, quicklime powder, and fluorite powder together with air to dealuminate the original ferrosilicon with high aluminum content. The production cost is reduced, more than 98% of aluminum in the original ferrosilicon is removed, and the method has good practical application prospects.
The smelting of low aluminum ferrosilicon powder is essentially a slag-free process. Some elements brought into the charge, such as Al and Ca, will enter the product after being reduced by carbon. In order to reduce Al, Ca, and other impurity elements in the low aluminum ferrosilicon powder, the technical solution of the present invention adopts out-of-furnace refining, that is, adding oxygen, iron powder, and other oxidants to the ferrosilicon. Liquid (steel ladle) to oxidize impurity elements Al and Ca into oxides and discharge slag. The aluminum content in the initial low aluminum ferrosilicon powder is 2.5% to 3.0%.
It should be noted that silicon can also spontaneously react with oxygen and iron fines during the refining process. In order to suppress or reduce the oxidation of element Si, the addition of oxygen and fine iron powder should be controlled to reduce the oxidation of Silicon. In addition, silica powder should be added, the formation of acid slag can also inhibit the oxidation of silicon.
In the refining dealumination outside the furnace, it is very important to choose a suitable composite slag agent. Composite slag agents must ensure a low melting point, good fluidity, and easy separation of slag and iron. The composite slag agent is generally a ternary system, that is, Al2O3-SiO2-Cao system and the final main components of refining should be: the amount of al2o3 is 15%-20%; the amount of CaO is 35%-40%; the amount of sio2- is 40% %~50%. The refining process adopts injection technology (injection technology is used to make the composite slag agent fully contact and react with the ladle during the stirring process of molten iron, and the effect of dealumination of low-alumina-silicon-iron powder is good. ).