Where does molten steel come from? First let the electric arc “ignite” the scrap steel. This article will explain how an electric arc furnace works and which parts should be bricked in three steps.
1.Arc starting
To put it simply: electrode discharge → scrap steel penetrates the core.
Press the button, and three graphite electrodes will descend, and an arc will be drawn as soon as they touch the scrap steel. The arc temperature instantly exceeds 3000℃, first burning out a molten pool directly below the electrode.
At this time, the hot spots on the furnace wall are concentrated. Therefore, high-purity fused magnesia carbon bricks need to be used close to the hot spots. Then, transition to the next section and use magnesia-alumina spinel bricks to buffer the temperature difference to prevent thermal shock from cracking the bricks.
2.Expansion of the electric arc furnace molten pool
The main processes are “oxygen blowing → boiling → heating”.
The arc continues to “eat” the material. While adding scrap steel, oxygen is blown, and the molten iron is tumbled for decarburization. At this time, the temperature is raised from 1500°C to 1600°C. The slag layer foams and chemical attack doubles.
Therefore, the slag line belt should be replaced with magnesia carbon bricks with a carbon content of 14%, so as to keep the slag out by virtue of the “non-wetting” property of carbon. The furnace bottom is paved with asphalt-bonded magnesia-calcium bricks, which take into account both corrosion resistance and slag protection. The temperature gradient within the section is large, and the brick joints must be staggered and locked. Only in this way can the steel be effectively avoided.
3.Steel tapping
Tilt furnace → gate → retain steel.
When the final carbon content reaches the standard, the furnace tilts forward and the molten steel flows into the ladle from the tapping hole. At this time, the slag surface drops, the hot bricks suddenly lose the protection of the slag layer, and the thermal shock is the most severe.
Therefore, it is necessary to put a circle of corundum-silicon carbide prefabricated parts around the steel outlet in advance, which can resist erosion and be easy to disassemble and replace.
Pour back into the furnace body, leaving 20% of the steel. The arc will start again in the next furnace, and the cycle will repeat. The life of the furnace lining depends on whether these fire bricks can withstand the alternation of hot and cold.
To make the electric arc furnace run more, first choose the right bricks for the hot spot, slag line and tapping port. At the same time, when looking for a refractory material supplier, pay close attention to the composition, density and high-temperature strength. Less downtime means more steel earned.
Henan Ruitai Lianxin Refractory Materials Co., Ltd. has been focusing on refractory materials for 20 years. It not only provides high-quality refractory bricks, but also provides customers with the most suitable kiln working condition solutions. Choosing Ruitai Lianxin means choosing strength.