Crude steel production in Iran

The history of the first attempt to establish an iron and steel factory in the country dates back to before 1930 AD (1309 AD). The outbreak of World War II stopped the construction of the iron and steel factory project in Iran. Two decades later, the two factors of improving the country’s economic situation and the increase in domestic demand for steel, […]

History

The first attempt to establish an iron and steel factory in the country dates back to before 1930 AD (1309 AD). The outbreak of World War II stopped the construction of the iron and steel factory project in Iran. Two decades later, the two factors of improving the country’s economic situation and the increase in domestic demand for steel provided the foundation for the establishment of the first steel products manufacturing plant in Iran. In this regard, a construction steel rolling unit was established in the country, which imported semi-finished steel products and carried out rolling operations on them, and offered its products to the market.

In the middle of the 1340s, Iran’s National Steel Industries Company was established to produce iron and steel by direct recovery methods. The first steel factory was built in 1350 in Isfahan and was put into operation in the same year. After the Islamic revolution in 1358, fundamental changes were made in the organization of Iranian steel industries, and domestic companies merged with each other and established a company called National Iranian Steel Company (NISCO).

From 1358 to 1379, Iran’s National Steel Company operated as the sole trustee of steel in the country. In 1379, according to Article 6 of the Law on Concentration of Industry and Mining Affairs and the establishment of the Ministry of Industries and Mines (approved in 1379), the Organization for the Development and Modernization of Mines and Mineral Industries (IMIDRO) was established, and the country’s steel producing companies such as Iran’s National Steel Company , Isfahan Mobarake Steel Company, Isfahan Zob Ahan Company and Khuzestan Steel Company were covered by the mentioned organization.

Today, the technologies used in the production of steel products are more or less the same in the stages after obtaining molten steel, i.e. casting and rolling. But to obtain molten or raw steel, different technologies can be used, including blast furnace (BF), electric arc furnace (EAF) and induction furnace (IMF). Although most of the production of crude steel in the world is by The blast furnace method is produced, but for several reasons, it is more justified to use the electric furnace method, especially in Iran.

A- Blast furnace (BF) method: It is a traditional method of iron production that uses indirect reduction of iron. In this way, first iron ore after processing and agglomeration (the process of pre-baking and clod formation of iron ore before charging to the blast furnace in steel factories) is entered into the blast furnace along with lime and coke and raw iron or molten pig iron. it will be obtained. In the next step, raw iron is converted into molten steel in a converter, and after removing carbon and other impurities with the help of oxygen, crude steel is produced. After the slag is discharged, the molten steel is sent to the continuous casting unit by means of molten steel carriers. In the continuous casting unit, the melt is poured into the mold and along the path of the roller it is sprayed with cool water and turns into a frozen ingot. Finally, the produced steel ingot is cut to the desired length.

Manufacturing factories in this way: Zob Ahan Isfahan

B- EFA electric arc furnace method:

In this method, scrap iron is first poured into the electric arc furnace using special baskets, and then, at the same time as the scraps are melted, a combination of sponge iron and slag-forming materials such as lime, coke, bentonite, and other additives are added from the top of the furnace to the melting. It is added and after sampling, oxygen blowing and homogenization, as well as various analyses, it turns into molten steel.

After discharging the slag, the molten mixture is sent to the continuous casting unit by the molten transfer bottles. In the continuous casting unit, the melt is poured through a nozzle into a container called tandish and then into a round water copper mold, and along the path of a roller it is sprayed with cool water and turns into a frozen ingot. Finally, the produced beds are cut to the desired lengths.

Sponge Iron or DRI, which is used in the production of steel ingots, is produced through the direct regeneration of pellets.

Manufacturing factories in this way: Mobarake steel, Khuzestan steel, Chadormello

C- IMF induction furnace method: with high frequency, it is widely used to produce tool steel (casting steel). Melting includes selected scrap with specific carbon. The scrap is placed in a cylindrical chamber of refractory material (crucible) which is surrounded by a water-cooled induction coil. A high-frequency alternating current passes through the coil and creates an alternating magnetic field inside the melt, which produces intense heat and also has a stirring effect. Not only is it possible to achieve high temperature, but precise temperature control is also possible. The capacity of the induction furnace varies from less than one kilogram to twenty tons, and it is used to melt cast iron and steel, copper, aluminum, and precious metals. . One of the major drawbacks of using an induction furnace in a foundry is its lack of purification capability; The charge material must be free of oxidation products and have a known composition, and some alloying elements may be lost due to oxidation (and must be added back to the melt).

All small and large workshops in the country use this method and produce products.

The method of producing all kinds of steel ingots:

1- Fabric: CCM continuous casting of steel means continuous and direct shaping of molten steel into semi-finished steel sections such as bloom, billet and slab, which are removed as a result of pellet production and then rolling in primary rolling units. Continuous casting is one of the most important production processes invented in the world in the steel industry, which has brought results such as improvement in quality, efficiency, productivity and economy in steel products. Today, more than 55.5% of global crude steel production is produced by this method.

2- manual (pouring)

Types of semi-finished steel products:

1- Ingot: The length of this product is less than 2 meters and its dimensions are optimized for steel transportation and storage. Its cross-sectional shape is trapezoidal.

2- Billet: Unlike ingot, billet is long and its cross section is a circle or square with a width of less than 15 centimeters (or a cross section smaller than 230 square centimeters). The billet is obtained through direct casting, extrusion, or through ingot rolling. Billet is mostly used to produce rebar and wire.

3- Bloom: If the width of the billet (shamshal) is more than 15 centimeters (or the cross-sectional area is more than 230 square centimeters), it is called bloom, and for this reason, these two products are usually placed in the same category (bloom and billet). they give. Bloom is used to make rails, iron beams, cans, studs, shields, etc. In the following, we will introduce slabs to clarify the difference between billets and slabs.

4- Slab or Takthal: (Slab), the cross-section of the slab is not square unlike Bloom and billet, but rectangular (usually 230 mm thick, 1.25 m wide and 12 m long). Slabs are used to make steel sheets, plates, etc. Note: Today, the technologies used in the production of steel products are more or less the same in the stages after obtaining molten steel, i.e. casting and rolling.

According to the above definitions, it can be concluded that the difference between these 4 products is in their cross section shape and dimensions.