Ferrosilicon is a kind of ferroalloys which is integrated of silicon and iron. The ratio of the two chemical substances are combined different, with the proportion of silicon ranging anywhere between 15% and 90% . This alloy is also known by the name of ferrosilicium. Its identification has known by CAS Number: 8049-17-0 and its chemical formula is “FeSi”.
There are a few methods to produce ferrosilicon.Ferro silicon can be produced by reacting the coke with silica. Or it can produce by obtaining this alloy in the submerged electric arc furnace for melting steel scrap and quartz together with a reductant. Then the hot liquid alloy will pour in a sandbed and after cooled will broke into small pieces. Depend on the ordered size; these small pieces can be crushed further to obtain the required size. Also there is another important byproduct which has produce by the large quantities of silica and its name is Microsilica which is obtained from this reaction.
Picture 1 – Ferrosilicon
Ferrosilicons is available in the worldwide market of varying silicon content. Ferrosilicons having a proportion of 15%, 45%, 75%, and 90% which silicon can be found and the rest is contains of iron. Other elements like calcium and aluminum usually have a presence of around 2% in the 75% of silicon.
Uses:
There are several uses of this alloy as below descriptions:
Chemical and Physical Properties
The physical and chemical properties of Ferro silicon are listed below:
Molecular Weight: The molecular weight for this alloy is 28.0855 g/mol.
Melting Point: The melting point of this substance varies with the content of silicon. FeSi 45 contains 45% silicon and its melting point ranges between 1215°C and 1300°C. FeSi 75 contains 75% silicon and its melting point ranges between 1210°C and 1315°C. FeSi 90 contains 90% silicon and its melting point ranges between 1210°C and 1380°C.
Boiling Point: The boiling point for this substance is 2355°C.
Density: The density of Ferrosilicon is different for different ratios of alloy compositions. FeSi 45 has a density of 5.1 g/cm3. The density of FeSi 75 is 2.8 g/cm3 and FeSi 90 has a density of 2.4 g/cm3.
Appearance: The shape of ferrosilicon powder particles can be spherical or irregular, like lumps, crushed or milled.
Corrosivity: It is resistant to corrosiveness and abrasiveness.
Color: The color of Ferrosilicon varies between silvery grey and dark grey.
Odor: Odorless; can be dangerous when inhaled.
Solubility: Ferrosilicon may react with water to produce hydrogen.
Combustibility: The dust particles of Ferrosilicon are combustible.
Specific Gravity: Specific Gravity of ferro-silicon varies with the proportions in which the two chemical substances are mixed. For FeSi 75, the specific gravity is 3.01.
MSDS
Ferrosilicon is a toxic, irritant and combustible substance. The alloy can be hazardous to human health. Toxic and flammable gases are produced when this alloy reacts with moisture, bases and acids. Hence adequate protection is needed from accidentally inhaling or ingesting the material.
While dealing with this alloy, care should be taken to protect the eyes and the skin. Ferro silicon is a stable substance. However, under certain conditions this material can also catch fire. It is thus important to adhere to adequate protective measures while dealing with this substance. The probable dangers posed by Ferro silicon and the protective measures one needs to follow are discussed below in details.
Introduction:
Silicon is one of the most abundant elements in the earth’s crust after oxygen. Silicon is commonly found in nature as quartz. Today, silicon is used in a variety of industries; But one of its alloys is ‘ferrosilicon’, which we study due to its wide application.
As mentioned, ferrosilicon is a mixture of iron and silicon. Ferrosilicon is produced by heating, reducing and smelting iron ore and silica (quartz) by carbon, mainly in arc furnaces.
Chemical compounds of ferrosilicon:
Its composition ratio is mainly from 10 to 90% of silicon and the rest of iron. Note, however, that impure elements such as manganese, phosphorus cream, sulfur, and aluminum in amounts less than 0.5% can be present in ferrosilicon. Carbon is present as an impurity (unwanted) as well as a third element in ferrosilicon types.
A variety of raw materials are used in the ferrosilicon production process. In addition to iron, about 2 to 4% of impurities such as aluminum, chromium, calcium, manganese, carbon, titanium, sulfur are also present in the composition of ferrosilicon.
. But in general, we examine these materials in three groups:
Ferrosilicon production is a slag-free process. The slag-free process includes all the elements in the raw materials that enter the product.
So far, more than 200 different types of minerals containing silica have been identified, but the most important minerals used in the ferrosilicon production process are:
• Quartzite
• Quartz
As mentioned, quartz and quartzite are used in the production of ferrosilicon; These materials must have the following properties:
The reduction of silica in the furnace is done by carbon. A variety of carbon materials can be used in the ferrosilicon production process, but the general properties of the suitable materials are as follows:
Each of these materials has only some of the necessary properties, and the set of properties does not exist in any of the above materials alone.
Iron carriers:
Some of the iron required in the product is supplied by reducing ash as well as the electrode shell, but in any case to supply iron it is necessary to use iron carriers in the charge mixture.
Due to the fact that iron contains a small amount of charge mixture, the properties of these materials are not very important compared to other materials used in the furnace. The only factor that is effective in choosing the right material is the chemical composition, the impurities should be in the least possible amount and less than five percent, and the amount of phosphorus should be less than 0.05 percent.
The iron materials used in ferrosilicon furnaces are as follows
• High purity iron ore
• Rolled oxide shell
• Iron sink pellets
• Turning chips
• Iron scrap
At present, the production of metal silicon and ferrosilicon in the world is done only by using the electric arc furnace method. In this method, the mentioned raw materials are continuously charged into the furnace with a specific granulation after mixing by loading pipes or loading machines. After a certain period of time, which is according to the power and electric current consumed by the furnace, between 2 to 4 hours, the metal produced is discharged from the furnace discharge ducts into the pan and transferred to the next paths which is casting. Arc furnaces for the production of ferroalloys are electrically similar to steel furnaces, but differ greatly in size and shape of the furnace from this type of furnace.
The most important issue in the production mechanism in each production unit is the transfer of materials within the factory on a regular basis and based on the necessary control criteria, manpower and its quantitative and qualitative characteristics.
The raw material transfer mechanism includes all activities that lead to the targeted transfer of raw materials from the material warehouse to the furnace.
The product transfer and preparation mechanism includes all the activities that lead to the conversion of the melt taken from the furnace to the ready-to-sell product.
An electric furnace for the production of ferrosilicon, with a temperature of more than 2,000 degrees Celsius, is a large heat source that heats nearby equipment and facilities. This heat will destroy or shorten their life if it is not removed from the equipment. For this reason, cooling different parts of the furnace by different methods is inevitable.
In addition to the round water cooling system of the furnace, to prevent the temperature rise in the floor of the furnace plant, the air blowing system is used to create proper ventilation for heat exchange with the environment. This is especially important in large furnaces, especially in processes such as the production of silicon, which requires high temperatures to carry out reactions.
Another important part of the cooling systems used in the arc furnace industry is the furnace transformer cooling system.
The process of ferrosilicon production is associated with the production of large amounts of gas and dust, which is primarily necessary to protect the environment and also to preserve the economic values of dust, the treatment of exhaust gases.
These alloys are used in the steelmaking and casting industries as an oxygenator and a chemical compound regulator according to the grade of steel and when the melt is discharged from the furnace to the pan or during secondary metallurgical operations.
The basis of ferrosilicon production is carbothermic reactions. And based on substance reduction reactions, including; Silica (quartz stone) and iron oxide with the addition of electrical energy along with reducing agents including; Carbon is reduced at the right temperature and ‘ferrosilicon’ is produced
In this process, raw materials including granulated silica rock and oxide crust along with reducing materials such as coal, coke and charcoal enter the smelting furnace through daily storage by the material transfer system. This charge is regenerated and melted by electrodes with a current of about 120 kA at a temperature of about 2500 ° C during an electrometallurgical process.
The largest consumers of ferrosilicon in the country are steel mills, which account for about 38,000 tons of total ferrosilicon consumption per year.
. Castings (such as Poladir Casting Company) also consume this material, which, taking into account the consumption of steelmakers, the total consumption of the country reaches about 50,000 tons.
One of the by-products of this ferroalloy is Microsilica, which is an odorless, non-combustible material with pozzolanic properties. For the production of one ton of ferrosilica, about 300 kg of microsilica is obtained, which is actually the result of collecting dust bag bags.
This product is used in concreting, refractory industries, paint and polymer industries.
One of the pioneers of this technology in the world is the Norwegian company ELKEM and the German SMS DEMAG. Norway has the highest production of ferrosilicon in Europe.
But now China has the highest production of ferrosilicon in the world, followed by Brazil, Russia and India.
In Iran, the first factory of ferroalloy industry was set up in 1372 with ELKEM Norway
technology in Azna city of Lorestan province. The second ferrosilicon production plant in Semnan works with a production capacity of 25,000 tons per year. In total, the total production of these two industrial units reaches about 100,000 tons per year.
For nearly two years, the third ferrosilicon production unit has been set up in Malayer city of Hamadan province with a capacity of 12,000 tons per year. Currently, several smaller units in Eshtehard and Kashan and… are also producing ferrosilicon.
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