Ferrosilicon, as its name suggests, is made up of silicon and iron. It is mainly used in the steel industry as a deoxidizer and alloying agent. In 6 Surprising Ways of Ferro Silicon Uses introduces the ferro silicon uses, while the ferro silicon manufacturing process will be covered in this article.
Ferrosilicon production raw materials
The raw materials of ferro silicon are silica, carbonaceous reducing agent, and steel scrap.
Silica for ferrosilicon production
The SiO2 content silica used for ferrosilicon production should be more than 97% because the reducing process of SiO2 requires a very high temperature. If with low content of SiO2, the content of Al2O3, and CaO in the silica will relatively high. This requires a higher reaction temperature, which in turn increases the consumption of power and reduces agents. And when smelting ferrosilicon, the oxide impurities will generate furnace slag.
Phosphorus and sulfur in the ferrosilicon are harmful elements that reduce the quality of steel. Therefore, the content of P2O5 in silica should be less than 0.02%. The content f sulfur element in the silica is low and disappeared easily in the smelting process due to its strong volatility.
The silica should have good burst resistance. If the silica is without good burst resistance, it will burst into small pieces during the heating process, which will affect the gas permeability of the charge. So the silica used in the ferrosilicon smelting should have good burst resistance, particularly in the large ferrosilicon electric furnace.
The size of the silica is also important. Commonly, the grain size of 40-100mm silica is used in the large electric furnace, the grain size of 25-80mm silica is used in the small electric furnace.
Carbonaceous reducing agent for ferrosilicon production
During the ferro silicon manufacturing process, there are various carbonaceous reducing agents such as metallurgical coke, charcoal, petroleum coke, asphalt coke, coal gas coke, bituminous coal, anthracite, etc.
The metallurgical coke is the most widely used reducing agent for ferrosilicon production.
The fixed carbon, ash, volatile matter, and moisture are important. The higher the fixed carbon the better, the fixed carbon content of metallurgical coke should be more than 84%. The ash content is less than 14%, the moisture is less than 6%.
A suitable size of coke should be used in ferrosilicon production. Coke with too large particle size has a small reaction surface and low reduction ability, while coke with too small particle size reduces the permeability of charge. The large electric furnace use 5-18mm coke, the small electric furnace use 1-8mm coke, and the size of 1-3mm is less than 20%.
The resistivity of the reducing agent should be large, and the porosity should be high.
The steel scrap for ferro silicon production
The steel scrap is used as an alloying agent for ferrosilicon production. It commonly uses carbon steel scrap. Non-ferrous scrap, alloy steel scrap, and pig iron steel scrap are prohibited.
The steel scrap must be without surface impurity. Rusty steel scrap cannot be used for ferrosilicon smelting, because the rusty steel scrap has poor strength, more powder, and high hydrogen content.
The iron content of steel scrap should be more than 95%.
Ferro silicon manufacturing process
- Raw materials preparation： high-quality ferrosilicon products depend on high-quality raw materials. Ensure the main ingredients of raw materials are up to standard, and control the amount of harmful impurties.
- Crush the materials into suitable grain sizes. Too large particle size will increase smelting energy consumption, too small particle size will affect the permeability of charge.
- Mixed the raw materials (Add coke, silica, and steel scrap in order Because they have different bulk density. The bulk density of coke is 0.5-0.6t/m3, the bulk density of silica is 1.5-1.6t/m3, the bulk density of steel scrap is 1.8-2.2t/m3. According to the adding order, the raw materials are uniformly mixed.
- Add them in charging chute. (Add charge evenly.)
- Smelt the furnace charge in the submerged arc furnace. The formation reaction of ferrosilicon: 6SiO2+12C+Fe=FeSi+5Si+12CO
- Collect the liquid ferrosilicon in the ladle.
- Pour the liquid ferrosilicon onto the beds for cooling.
- Break the ferrosilicon natural block into customer required size and pack them into 1MT jumbo bags.
Ferrosilicon production furnace
Ferrosilicon is smelted in a reduction furnace with continuous operation.
During the ferro silicon production process, the electrodes are inserted in the charge. Electrodes are inserted in the charge deeply and steadily. Adding the raw materials continuously ensures a certain amount of charge in the furnace. The molten ferrosilicon runs off through the tapping hole when produced to a certain amount.
Ferrosilicon production is a slag-free method. In the actual production, there will be some slag. The composition of the slag is Al2O3 45%-62%, SiO2 23%-46%, CaO 9%-18%. The slag not only increase the energy cost but also make the furnace deteriorates due to its high melting point and high viscosity.
Some of the ferro silicon manufacturers add a suitable amount of lime to remove the slag from the furnace.
This article is only an overview of the ferro silicon manufacturing process. During the production process, there are many details to pay attention to such as the proportion of ingredients, the charging sequence, removing slag, and so on. To study the production process of ferrosilicon in depth and detail, please contact us through the website to explore more advanced ferrosilicon production technology.