The main functions of a steelmaking furnace include smelting, refining, alloying, and casting. Specifically:
Blast Furnace:Primarily used for producing pig iron. The steelmaking process in a blast furnace mainly includes three stages: charge pretreatment, reduction smelting, and temperature rise. Charge pretreatment includes ore crushing, screening, and batching. These steps ensure the uniformity and stability of the charge composition, which is beneficial for the subsequent reduction smelting process. In the reduction smelting stage, the charge is gradually pyrolyzed and reduced, producing liquid iron and slag. The blast furnace can also transfer impurities from the iron to the slag at very high temperatures, continuously purifying the quality of the molten iron. Therefore, the blast furnace plays a role in separating metals from non-metals.
Electric Furnace:A device that heats the charge using electricity, using artificial quartz sand and graphite heat sources to heat scrap steel or pig iron for smelting. Compared to traditional blast furnaces and converters, electric furnaces offer faster reaction times, better purification effects, precise control of furnace temperature and internal environment, and more uniform quality molten iron. Electric arc furnaces (EAFs) can also perform various specific process reactions by combining different oxidizing and reducing agents, such as sulfur oxidation, phosphorus reduction, and chromium addition. These reactions result in steel with superior properties. EAF steelmaking typically involves three stages: melting, oxidation, and reduction, creating both oxidizing and reducing atmospheres within the furnace, thus significantly improving dephosphorization and desulfurization efficiency. Compared to blast furnaces and converters, EAF steelmaking using scrap steel offers the advantage of lower infrastructure investment.
AOD furnaces: These are advanced technologies for refining stainless steel. They are widely used due to their simple equipment, convenient operation, strong adaptability, low investment, and low production costs. During the smelting process, blast furnace molten iron and molten steel from the electric arc furnace are injected into the AOD furnace. A mixture of O2, Ar, or N2 gases is blown in to decarburize the steel. Simultaneously, reducing agents, desulfurizing agents, ferroalloys, or coolants added through the charging system are used to finely adjust the steel composition and temperature, ultimately producing qualified stainless steel. In refining, the delivery and regulation of the mixed gas is one of the core systems of the AOD furnace. After processes including oxygen production in the oxygen-generating workshop, pipeline transportation, metering, pressure reduction, regulation, and mixing, the gas is fed into the furnace at the required flow rate and proportion. At the start of smelting, oxygen is blown into the molten metal pool from the top furnace opening through double-layered water-cooled oxygen blowing pipes for decarburization. During the refining stage, the mixed gas is fed into the furnace through side lances.
LF Furnace: The refining process integrates multiple technologies, including argon stirring in a low-oxygen atmosphere, graphite electrode heating, and the utilization of white slag. These technologies work together to significantly reduce the oxygen and sulfur content in the steel, achieving inclusion levels of ASTM rating 0-0.1. The LF furnace can also work in conjunction with electric furnaces or oxygen converters to produce high-quality alloy steel. In continuous casting workshops, especially on alloy steel continuous casting production lines, the LF furnace is an indispensable device for controlling composition, temperature, and preserving molten steel. The LF furnace offers several advantages, including efficient desulfurization, precise temperature control, fine-tuning of composition, improved steel purity, and flexible slag formation. When connected to an electric arc furnace, it can shorten the furnace production cycle and improve steel quality. When connected to an LD converter, it can perform reduction refining on converter steel, thereby improving steel quality and expanding the production capacity of new steel grades. Strict control of the steel composition and temperature is beneficial to improving the hardenability of steel and the continuous casting process of special steels. After AOD refining, the molten steel enters the LF furnace for secondary refining to further reduce inclusions and ensure high purity of the molten steel.