Matching of Electric Furnace Steelmaking with Upstream Processes

author: Anna

2024-06-25

Matching of Electric Furnace Steelmaking with Upstream Processes

(1)Traditional electric furnace steelmaking uses scrap steel as the main raw material, and adds 10% to 15% pig iron to ensure a certain carbon content. Generally speaking, scrap steel raw materials at room temperature (25°C) have very little physical heat.

Under the conditions of oxygen blowing and fluxing, the chemical heat generated by cold furnace materials is not much, and the smelting process requires a large amount of external heat energy.

According to various statistical data in my country in recent years, the energy consumption of electric furnace steelmaking process (including refining, continuous casting and workshop auxiliary projects) is 250 to 300 kg, slightly higher than the results of the International Iron and Steel Association IISI.

(2) Using hot iron in different proportions as raw material, the electric furnace steelmaking process has achieved significant benefits. The main reason is that hot iron is a carrier with high physical and chemical heat and low cost.

Putting electric furnace steelmaking into the process, it is not difficult to see that the physical heat and chemical heat carried by hot iron come from the previous blast furnace ironmaking process.

According to the actual data of 300-380 m3 blast furnaces of some enterprises, the energy consumption of blast furnace ironmaking process is 377 kg to produce 1 t of hot iron, which is equivalent to 3080 kW h/t.

Considering the processes of sintering, pelletizing and coking, the energy consumption per ton of hot iron is 500-550 kg/t, that is, 4084-4493 kW h/t, while the physical heat and chemical energy brought by hot iron to the electric furnace steelmaking process is only 600-650 kW h/t.

(3) At present, the proportion of domestic electric furnaces equipped with heated iron is 25%-30%. Based on an annual output of 1 million tons of steel, 300,000 to 350,000 tons of molten iron are required per year. The blast furnace utilization coefficient is taken as 3 t/(m3:d), and the blast furnace volume is 300 to 350 m3.

(4) Use of direct reduced iron. Using direct reduced iron to provide a pure iron source for electric furnace steelmaking has been an important development direction in recent years.

The output of various direct reduced irons worldwide has increased by more than 1 times since 1990. In recent years, the output has exceeded 40 million tons/a, which is about 15% of the output of electric furnace steel and has become an important iron source for electric furnace steelmaking.

The production technology of direct reduced iron has made rapid progress, especially hot-pressed briquettes (HBI) with a w(C) of nearly 2%, which provide a high-density, high-chemical-energy pure iron source for electric furnace steelmaking.

The production technology of direct reduced iron worldwide is dominated by the gas-based method, which accounts for 90% of the direct reduced iron production. However, my country lacks natural gas and has few high-quality iron ores, and resources limit the development of direct reduced iron production technology.

Currently, the largest direct reduced iron production plant in China is Tianjin Steel Pipe Co., Ltd., and the energy consumption per ton of direct reduced iron is about 900~1000kg.

Electric Furnace Steelmaking Technology

Electric Arc Furnace Steelmaking Process