The steel industry is a basic industry supporting the national economy and also the industrial sector with the largest carbon emissions in the manufacturing sector. Its green and low-carbon transformation is of great significance.
What is short-process electric furnace steelmaking? In the steel industry, there are two main smelting processes. One is the “blast furnace-converter” long-process steelmaking with iron ore as the main raw material, commonly known as converter steel, and the other is the short-process electric furnace steelmaking with scrap steel as the main raw material, commonly known as electric furnace steel.
Unlike long-process steelmaking, the main raw material of short-process electric furnace steelmaking is scrap steel, and the process omits coking, sintering, blast furnace ironmaking and other relatively high pollution, energy consumption and carbon emission links.
The short-process electric furnace steelmaking process is adopted, which has significant effects in reducing carbon emissions.
Scrap steel is being crushed and machines are roaring. Walking into the scrap steel processing workshop, two large gantry shears and one high-power crusher are shearing and crushing strip and plate-shaped scrap steel.
In the electric furnace workshop, two double-shaft scrap steel preheating DC arc furnaces are very conspicuous. After sorting and processing, the scrap steel will be sent to the batching room, loaded into the material basket, and then sent to the top of the electric furnace for preheating, and then melted into molten steel through the electric furnace.
This electric furnace uses a unique scrap preheating method, which can use the waste heat of production to raise the scrap steel temperature to 600 to 800 degrees Celsius, thereby shortening the scrap steel melting time and improving production efficiency. Subsequently, the molten steel flows into the ladle along the steel outlet and is sent to the refining workshop for refining and vacuum treatment, and then completes continuous casting.
Green and low-carbon development is a new requirement and trend in steel production. In 2018, when the construction of the new plant started, the long process of the old plant was abandoned and the short process was firmly chosen.
“Ore, coking coal, coke, and pellets, the raw materials that were once necessary for steel production, have now disappeared from the procurement list. The raw materials used have become various types of scrap steel, and the working environment has become cleaner. According to preliminary calculations, compared with the old plant, the comprehensive energy consumption per ton of steel in the new plant has been reduced by 62%, the water consumption per ton of steel has been reduced by 46%, and the main pollutants such as particulate matter, sulfur dioxide, and nitrogen oxides have been reduced by 75%.
In addition, short-process electric furnace steelmaking has the advantages of flexible production organization and strong adaptability to raw materials. Long-process steelmaking has a series of processes and complex chemical reactions. Even if the market fluctuates and production needs to be adjusted flexibly, the blast furnace cannot be easily stopped, otherwise it will cost a lot to restart.
The short-process process does not have a blast furnace ironmaking link, which avoids these problems and makes the production organization more compact and efficient. The short-process process can also flexibly adapt to different types of scrap steel raw materials and convert them into steel products.
“The short-process electric furnace steelmaking with pure scrap steel emits about 1.5 tons less carbon per ton than the long-process steelmaking with ‘blast furnace-converter’, and is the most effective way for the steel industry to reduce carbon dioxide emissions. In the future, one of the main paths for the steel industry to reduce carbon emissions is to develop short-process electric furnace steelmaking.” Relevant responsible persons of the China Iron and Steel Association believe that in promoting energy conservation and carbon reduction in the steel industry, the roles and carbon reduction contributions of “blast furnace-converter” and electric furnaces are different in the first and second half. In the first half, the reduction of total carbon emissions depends on the long process, and in the second half, the realization of carbon neutrality depends on the short process.
With strong policy support and rapid industry development, the proportion of electric furnace steel is expected to gradually increase
Electric furnace steelmaking has the advantages of low investment, short construction period, flexible production organization, and obvious energy saving and carbon reduction effects. So, compared with long-process steelmaking, how is the economic efficiency of short-process steelmaking?
Let’s look at the long process first. Recently, the price of one ton of iron ore is less than 1,000 yuan. The iron ore is melted into molten iron through blast furnace ironmaking and other processes, and the cost per ton is more than 2,000 yuan.
Let’s look at the short process. At present, the purchase price of 1 ton of scrap steel is more than 2,000 yuan, which is similar to the cost of molten iron in the long process of steelmaking. However, molten iron is hot and can be used directly for steelmaking without adding other heat sources, while scrap steel is cold and needs to rely on electrodes to generate high temperatures to melt it before it can be used for steelmaking. In other words, the short process has an additional electricity cost.
“All in all, assuming that other costs such as labor are similar, the price of scrap steel per ton must be at least 300 yuan lower than the cost of molten iron, and electric furnace steelmaking can only be competitive to a certain extent,” said Liu Shuguang.
In order to reduce electricity costs, many electric furnace steel companies will formulate production plans according to the peak and valley electricity price periods to reasonably stagger production. At Hangda Steel, the operation time of the electric furnace is from 21:00 to 15:00 the next day, covering the valley period from 23:00 to 7:00 the next day, avoiding the peak period from 15:00 to 21:00, saving 50 to 60 yuan per ton of steel.
Although the economic efficiency needs to be improved, many interviewed companies believe that in the long run, the market competitiveness of short-process steelmaking with electric furnaces will gradually increase. “With the continuous advancement of new industrialization and new urbanization, the amount of scrap steel will continue to increase, the raw material cost of short-process steelmaking will gradually decrease, and the gap with long-process steelmaking will gradually narrow. In the international market, many customers have proposed to purchase “zero-carbon steel” or “low-carbon emission steel”, and greener and lower-carbon electric furnace steel is more popular than converter steel.
