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Steel production in electric arc furnace steelmaking is growing rapidly
In recent years, the production of steel using electric arc furnaces (EAF) has experienced significant growth, outpacing the overall increase in global steel output. In 2000, the world's total steel production reached 1,068 million tons, with EAF steel accounting for 283.52 million tons, representing 26.5% of the total. Compared to 1995, EAF steel output surged by 168%, while total steel production grew by 132%. This rapid development is largely attributed to the availability of scrap metal and low electricity costs in developed countries. For instance, in the U.S. and Japan, EAF steel accounted for 46.8% and 28.8% of their respective total outputs in 2000. However, in China, where scrap resources are limited and electricity prices are high, EAF steel production was only 20.2 million tons in 2000, making up 15.9% of the country’s total steel output.
During the 1990s, large-capacity and ultra-high-power electric arc furnaces saw considerable progress in China. Initially, most EAFs were used for producing alloy steels, typically found in special steel plants, with capacities below 50 tons. From the 1970s to the late 1980s, smaller electric arc furnaces were built, often paired with small rolling mills to produce low-grade steel. These operations suffered from poor product quality, high energy consumption, and environmental pollution. As a result, many small steel mills were phased out, leading to a decline in scrap recovery, which dropped to around 5 million tons by the 1990s.
China has since invested heavily in building large-scale, ultra-high-power EAFs, significantly advancing its steelmaking technology and narrowing the gap with global leaders. Between 1990 and 1999, 19 ultra-high-power EAFs with capacities ranging from 60 to 150 tons were constructed, adding a total capacity of 1,645 tons. After 2000, more than 50 EAFs with capacities exceeding 50 tons were commissioned. Currently, there are 39 EAFs over 50 tons, and 10 units with single furnace outputs above 100 tons. These modern facilities are equipped with ladle refining (LF), continuous casting (CCM), and vacuum degassing (VD) systems to ensure high-quality steel suitable for demanding applications such as oil pipes and high-pressure boiler tubes.
To enhance steel quality, the charge composition in EAFs has been improved. Traditionally, all scrap steel was used, but this introduced harmful residual elements like lead, tin, arsenic, zinc, and copper. To mitigate this, some plants now add molten iron or direct reduced iron (DRI) to dilute these impurities. For example, a 150-ton DC arc furnace producing high-strength oil well pipe and boiler tubes uses 30% blast furnace hot metal in its charge, effectively reducing harmful element content and meeting stringent quality standards. However, this also increases power consumption during smelting.
DC arc furnaces offer several advantages over traditional three-phase AC furnaces, including 50% lower electrode consumption, reduced refractory wear, lower energy use, shorter smelting times, less grid interference, and quieter operation. The DC current passing through the molten bath generates strong electromagnetic forces, promoting better stirring and uniformity in the molten steel.
Oxygen-blowing technology has also played a key role in boosting EAF productivity. Oxygen and natural gas-based oxygen guns have become essential tools for intensifying the smelting process, particularly in ultra-high-power EAFs. Chinese steel plants have optimized their processes by selecting appropriate oxygen blowing devices, resulting in faster smelting cycles and increased output.
High-quality refractory materials have been crucial in extending the life of EAF linings. As power levels have increased, so has the thermal load on the lining, causing it to degrade more quickly. By the 1980s, lining life was generally under 100 heats. Today, advanced refractories such as high-aluminum bricks, corundum, magnesia-chrome bricks, and asphalt-bonded magnesia bricks are used, significantly improving lining durability and operational efficiency.
In conclusion, China's EAF steelmaking industry saw rapid development in the 1990s, enhancing both technology and equipment. However, challenges remain, including underutilized large EAF capacities and the need for localized production of key components. High scrap and electricity costs continue to drive up production costs, making it essential to reduce scrap prices and energy consumption. Additionally, phasing out inefficient small EAFs could help alleviate scrap shortages. Finally, adding molten iron or DRI to certain EAF charges can improve the quality of high-performance steels, supporting the industry's long-term growth.