Steelmaking And Casting
The most important section in steelmaking is the electric arc furnace.
Electric arc furnaces can be used for manufacturing construction steel, high-alloy steels, and high-carbon, low-carbon, and high-strength steels, among others. The first phase of the steelmaking plants in South Kaveh Steel Company includes a 210-ton HSS electric arc furnace (discharge of 170 tons) for manufacturing construction steels.
Electric arc furnaces can consume high-percentage sponge iron. However, in order to create the initial molten bath in these furnaces, a specific percentage of scraps (about 2 percent of the total metal charge) is added to the furnaces. After creating the molten bath, the sponge iron charge and the lime are added at the same time as the electric arc, and the injection of oxygen, natural gas, and coke by the jet burners. By injecting oxygen, coke, and lime to the molten materials in the arc furnace, a puffy slag is created. In addition to coating the arc, maintaining its stability, and increasing its energy efficiency, the puffy slag prevents the severe corrosion of the insulation, and helps the refinement of the arc, especially helping the DE phosphorylation in the furnace. Therefore, controlling and maintaining the puffy slag with good basicity in furnaces are very important. The injection of oxygen and carbon along with natural gas by the jet burners is an exothermic process, and it reduces the energy consumption and waste. The electrical energy consumption by the arc furnace unit of the first phase of the steelmaking plant with a 170 MVA transformer with a maximum instantaneous power of 125 MW is about 650 KWH/ton.
In general, the raw materials used in the electric arc furnace include electrodes:
- insulating materials
- scraps and sponge iron
- briquette
- lime
- dolomite
- coke
- ferroalloys
- and other additives.
After preparation in the electric arc furnace, initial metallurgy, and increasing the temperature of the molten material to about 1620 to 1640 degrees Celsius, the molten material in the furnace is discharged into a ladle, and it is then sent to the ladle furnace section.