Electric arc furnaces (EAFs) primarily rely on electric energy as their power source. Through the discharge between graphite electrodes and the charge, electric arcs are generated, creating extremely high temperatures ranging from 2000℃ to 6000℃ or even higher. Scrap steel raw materials are melted via arc radiation, temperature convection, and heat conduction.
During most of the charge - melting period, the high - temperature heat source is surrounded by the charge. As a result, the heat loss caused by high - temperature exhaust gases is relatively minimal. This gives EAFs a higher thermal efficiency compared to other steelmaking equipment like converters. Moreover, electric heating allows for precise control of the furnace temperature. The heating operation can be carried out under various conditions, including oxidizing or reducing atmospheres, normal pressure, or vacuum, according to specific process requirements.
The EAF steelmaking process is relatively short. The equipment is simple in structure, and the operation is convenient. Pollution control is also relatively straightforward. In terms of construction investment, EAFs require less capital compared to converter - based steelmaking systems. They also occupy a smaller area and do not depend on a complex iron - making system like converter steelmaking does.
EAF steelmaking demonstrates high adaptability to different types of charges. While scrap steel is the main raw material, it can also utilize molten iron (from blast furnaces or hot metal furnaces), sponge iron (DRI), hot briquetting (HBI), pig iron, and other solid and liquid iron - containing materials.
Since the atmosphere inside the EAF can be precisely controlled, slag adjustment or replacement operations are relatively easy. A series of complex process operations, such as melting, decarburization, dephosphorization, degassing, inclusion removal, temperature control, and composition adjustment (alloying), can be completed within the same operating system. EAFs can operate intermittently, and production varieties can be flexibly changed within a certain range.
In addition, modern EAFs can make use of a large number of auxiliary energy sources, such as injecting heavy (light) oil, pulverized coal, and natural gas. This further enhances the adaptability and operational flexibility of the EAF steelmaking process, expanding its range of applications.
EAFs are capable of smelting high - quality steel with low levels of phosphorus, sulfur, and oxygen. They can also be alloyed with a variety of elements, including those that are easily oxidized like lead, boron, vanadium, titanium, and rare earth elements. This enables the production of a wide range of high - quality steels and alloy steels, such as ball - bearing steel, stainless acid - resistant steel, tool steel, electrical steel, heat - resistant steel, magnetic materials, and special alloys.
Despite these numerous advantages, in China, due to the current costs of scrap steel and electricity prices, EAF steelmaking generally cannot compete with converter steelmaking in the production of ordinary steel and long - term products. EAFs mainly hold a leading position in the production of special steels that are produced in small batches, have multiple varieties, and high alloy ratios.
At present, some short - process electric furnace manufacturers worldwide generally use high - output EAFs. The traditional three - phase operation process with a reduction period has been gradually replaced by combined process technologies such as out - of - furnace refining. As a result, EAFs and their public auxiliary facilities and equipment have become more complete and reasonable. The proportion of electric furnace steel output in the world is increasing year by year.
In China, as a developing country, infrastructure construction is still in its early stages, and the large - scale scrap steel recovery period has not yet arrived. Moreover, the country's power development is uneven, and electricity prices remain relatively high. These factors limit the development speed of EAF steelmaking in China, preventing it from experiencing rapid growth like converter steelmaking. Although the total amount of electric furnace steel is increasing, the proportion of electric furnace steel output in the total steel output has been decreasing year by year, which is contrary to the global development trend of EAFs.
However, with the development of China's power facilities, the accumulation of scrap steel resources, and the country's strengthening of environmental protection and mineral resources management, the development trend of China's EAF steelmaking is expected to rise. In the future, China's EAF steelmaking technology will achieve more comprehensive development.
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