Why are electric arc furnaces better than converters? The answer will become clear after reading this article.
1.Heat source temperature
In terms of heat source temperature, electric arc furnaces are more concentrated, while converters rely on oxygen blowing.
In an electric arc furnace, graphite electrodes are inserted into the furnace charge, and the arc light instantly raises the local temperature to over 3,000 degrees Celsius. At this point, the heat is concentrated, and the temperature rises rapidly.
The converter relies on top-blown oxygen to react with the molten iron and release heat. Although the temperature is sufficient, it is scattered and fluctuates greatly.
Therefore, the electric arc furnace can melt the cold material within ten minutes. However, the converter requires the molten iron to be prepared to 1,300 degrees Celsius before blowing, which takes a long time and consumes a lot of energy.
2.Raw materials
Electric arc furnaces offer flexible material preparation, while converters are limited by the amount of molten iron.
In an electric arc furnace, scrap steel, direct reduced iron, and alloys can be freely mixed, and the proportion can be adjusted to 100% scrap steel. The converter must contain more than 70% molten iron, and scrap steel is only used as a “cooling agent”.
This means that electric arc furnaces can recycle scrap steel into new steel, but converters cannot function without blast furnace molten iron, and the process is locked up by upstream processes.
3.Electric arc furnaces are more environmentally friendly
From an environmental perspective, electric arc furnaces have lower emissions and require less refractory material for the kiln.
Electric arc furnaces use electricity and have no additional combustion inside. Therefore, their carbon dioxide emissions per ton of steel are half that of converters. Dust and sulfur dioxide are also reduced simultaneously. Although the furnace temperature is high, the molten pool is calm, and the refractory bricks are only affected by arc pitting and chemical erosion. Therefore, it can be constructed using magnesia-carbon bricks or magnesia-calcium bricks in layers, resulting in a stable lifespan.
The high-temperature airflow in the converter causes intense scouring. Therefore, it requires the entire furnace to be lined with high-grade magnesia-carbon bricks, resulting in a high frequency of maintenance.
In other words, electric arc furnaces have lower environmental impact and lower refractory material costs than converters.
Finally, even if you choose the right furnace, you still need to match it with good refractory bricks. High-carbon magnesia-carbon bricks are used in the hot zone of the electric arc furnace, magnesia-calcium-carbon bricks are used in the slag line, and corundum spinel precast blocks are used in the transition zone to ensure a longer service life.
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