Measures to Improve the Service Life of Electric Arc Furnace Lining

The refractory materials used for electric arc furnace construction have strict standards for performance indicators such as alumina content, bulk density, room temperature compressive strength, high temperature flexural strength, and apparent porosity. Magnesia carbon brick has the characteristics of good corrosion resistance, high temperature strength, and long service life, and is widely used in masonry furnace lining.

The quality of furnace lining masonry should be strictly controlled. When laying various types of road lining bricks, attention should be paid to flatness, and the brick joints should be controlled within 2-3mm. The furnace entrance and steel outlet should be strictly built according to the requirements. In the early days, wind hammers were often used to tie tar magnesia lining as a whole, which resulted in poor working conditions for workers. At the same time, the lining had low bulk density, high porosity, poor resistance to slag erosion and scouring, and severe slag line erosion during the smelting process. After using tar magnesia sand combined with bricks for masonry, not only did the production process become mechanized and automated, but the bulk density also increased from the original 2.3 to over 2.8. The resistance to slag erosion and erosion was greatly improved, especially near the slag line and steel outlet, where the resistance to erosion was significantly enhanced.

The lifespan of the furnace lining is closely related to the distribution of the electrode core circle (the circle formed by the center of the electrode hole with a equilateral triangular distribution). The diameter of the electrode core circle determines the distribution position of the electrodes and the power distribution of the three-phase electrodes, which has a significant impact on the melting rate of the furnace charge and the service life of the furnace lining. Increasing the diameter of the electrode core circle, placing the electrode close to the furnace wall, and accelerating the erosion rate of the furnace lining under the high temperature of the arc, while reducing the heating of the furnace material in the middle of the furnace body; Reducing the diameter of the electrode core circle can cause localized high temperatures in the steel material in the middle of the furnace, while the melting rate of the material on the slope slows down. According to the experience of steel mills, the best furnace lining life is achieved when the electrode circle diameter is equal to 0.35-0.39 of the melting chamber diameter at the level of the furnace door. The minimum coefficient is used when the melting chamber diameter of the electric furnace is larger.

The lifespan of furnace lining is related to various factors and closely related to smelting operations. Incorrect smelting operations can shorten the lifespan of furnace lining. It includes strict power supply system to control the temperature of molten steel, charge treatment and charging, promotion of foam slag process, reasonable organization of production, reduction of smelting time, etc.

Adding an appropriate amount of lightly burned dolomite to the furnace charge can increase the MgO content in the slag and increase the alkalinity of the slag, which can reduce the erosion of the furnace lining. The repair work is an important link in improving the service life of the furnace lining, which can effectively reduce the wear and tear of the furnace lining. Generally, the dry spraying method is used to strengthen the spraying of severely eroded areas such as the sides of the furnace door, the steel outlet, and the No. 2 slag line as soon as possible after tapping. Spray repair is based on the principles of uniform repair, fast repair, and thin repair, with the aim of improving the adhesion rate of spray repair materials, reducing heat loss, achieving good sintering effect, and reducing furnace lining erosion. When there are large pits in the furnace bottom, wet patching method is used, using brine or water glass as adhesive. Timely maintenance of furnace lining can effectively extend the furnace life.