Steelmaking

Steel production is a complex process that consists of several stages. In the following, I will briefly mention the stages of steel production:

Steel making

1. Iron ore extraction: First, iron ore is extracted from the mine. Then these iron ores are turned into lumps and pellets by stone crushers.

2. Processing: After extracting and preparing iron ore, it is put into the furnace along with coking coal.

3. Steel making: All these materials are injected into the furnace and after being heated (by fuel combustion and air blowing) they become molten iron (pig iron).

Iron ore mining

Iron ore extraction is one of the basic steps in steel production. This process consists of several steps:

1. Discovery: First, the places that have iron ore deposits are identified. This is usually done with geological surveys and geophysical tests.

2. Drilling: After identifying the location, the drilling operation begins to access the iron ore. Excavation can be open or underground¹.

3. Blasting: Explosives are used in open pit mines to break and crush large rocks.

4. Loading and Transportation: After blasting, crushed rock is loaded by loaders and trucks and transported to processing plants.

5. Processing: In processing plants, crushed iron ore is subjected to processes such as washing, granulation and magnetic separation to increase its iron grade².

These steps lead to the production of iron concentrate, which is the raw material for steel production. Iron ore is found in nature in the form of various minerals such as hematite and magnetite, each of which has unique characteristics.

processing

The iron ore processing stage includes several processes whose purpose is to increase the grade of iron and remove impurities so that the final product is suitable for steel production. Here I explain the key stages of iron ore processing:

1. Crushing: The mined iron ore is first transported to a processing plant where it is crushed into smaller sizes¹.

2. Screening: After crushing, iron ore is passed through screens to be granulated according to size².

3. Magnetic separation:In this step, iron is separated from other materials using magnetic separators. This process is done for rocks with magnetic properties like magnetite¹.

4. Enrichment: This stage includes the use of various methods such as washing, flotation or gravity separation to increase the iron grade and remove impurities².

5. Dewatering: After enrichment, the resulting product must be separated from water so that it can be transferred to blast furnaces for steel production in the form of iron concentrate or iron pellets.

These steps lead to the production of iron concentrate, which is the raw material for steel production. Iron concentrate has a higher grade than raw iron ore and is used to produce steel in blast furnaces.

Steelmaking by blast furnace method

Steelmaking is a process in which steel is produced from iron ore or scrap iron. This process includes several steps that I will mention below:

Blast Furnace

1. Blast Furnace: In this stage, iron ore, coke (processed coal) and limestone are placed in the blast furnace to produce pig iron.

2. Primary steelmaking: raw iron obtained from the blast furnace is transferred to steelmaking furnaces along with iron scrap. At this stage, impurities such as sulphur, phosphorus and excess carbon are removed and alloying elements such as manganese, nickel, chromium and vanadium are added to produce steel with the desired properties¹.

3. Secondary steelmaking: This stage includes further refining of molten steel and modification of its composition. May include desulfurization, vacuum refining and addition of other alloying elements.

4. Casting: Molten steel is poured into molds to form the required shapes such as bars, bars or sheets.

5. Rolling and final processing: Raw steel is rolled and shaped into sheets, bars or other finished products.

These processes are constantly being improved and evolved to increase the quality of steel produced and reduce costs. Due to its high mechanical properties and relatively low price, steel is used in many industries, including construction, automobile manufacturing, and machinery manufacturing.

oxygen based steelmaking (BOF)

Steelmaking based on oxygen, which is also called alkaline oxygen process or BOF process (Basic Oxygen Furnace).

1. Furnace charging: About 70% of molten iron is charged from the blast furnace along with iron scraps into the alkaline oxygen furnace.

2. Blowing oxygen: Pure oxygen is blown into the furnace at supersonic speed. This oxygen reacts with the carbon and silicon in the furnace and

Steelmaking by electric arc method

produces a lot of heat, which leads to the melting of the steel.

3. Chemical reactions: In this process, the oxidation of iron, manganese, and phosphorus also produce heat, and the carbon monoxide created while leaving the furnace also gives its heat to the furnace.

4. Steel production: The output from this furnace is molten iron with special chemical properties, which is at a temperature between 1,590 and 1,650 degrees Celsius and is refined in the next steps.

This method has advantages over older methods such as the Bessemer converter, which blew air instead of pure oxygen. Air blowing brought problems such as nitrogen dissolution in steel and steel quality decline. Alkaline oxygen process solves these problems by using pure oxygen and provides a more efficient and quality process.

The steel produced by this method is used in various industries such as construction, automobile manufacturing, machinery manufacturing and many other industrial and consumer applications.duction:crushers.coal.

Steelmaking by electric arc method(NEOF)

The Electric Arc Furnace (NEOF) is one of the modern steelmaking methods used to melt metals using the heat generated by an electric arc.

1. Furnace charging: At first, raw materials, which are usually scrap iron, sponge iron or blast furnace ingots, are charged into the furnace.

2. Melting: Then, using graphite electrodes, an electric arc is created between the electrodes and the metal load, which causes the material to melt. The furnace temperature can reach about 1600 degrees Celsius.

3. Alloying and refining: after melting, the molten steel is transferred to the patili furnace, where alloying and refining operations are performed. This involves adjusting the amount of carbon and adding alloying elements to achieve the desired chemical composition.

4. Casting: Refined steel is then transferred to casting molds and transformed into required shapes such as plates, bars or sheets.

Electric arc furnaces can be divided into two categories, AC and DC. DC furnaces have one graphite electrode and current flows from the cathode side to the anode, while AC furnaces have three graphite electrodes and the waste itself acts as the anode.

This process has advantages due to better heat control and the possibility of adding more alloy than other methods. Also, this method has environmental benefits, as it allows the reuse of scrap iron and helps reduce the need to mine new iron ore.

References

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