Improving the service life of the furnace lining is an important part of the maintenance of the electric arc furnace. This article introduces the 6 main factors affecting the life of EAF lining, which we pay attention to and take into account when we provide turnkey services for customers in furnace design and production management.
The influence of high temperature heat
The lining of steelmaking arc furnace is often in a high temperature state, and the general smelting temperature is often above 1600℃. In addition, the lining must withstand rapid cooling and heating. Although this phenomenon is inevitable in the smelting process, the degree and time of high temperature heat should be reduced or shortened as much as possible, such as rapid furnace patching and charging, ensuring normal operation of equipment, and minimizing hot shutdowns, which are all conducive to improving the service life of the lining.
The influence of chemical erosion
During the steelmaking process, various chemical reactions are carried out from beginning to end, especially at the slag-steel interface, which is more intense. The main reason for the formation of slag line lies in this. The refractory material of the lining is very easy to peel off under the action of chemical reactions. Normal slag contains 5%-10% MgO, which is the result of this erosion.
Chemical erosion is related to the composition and fluidity of the slag. When the content of acidic or eccentric oxides such as SiO2, P2O5, Al2O3 or Fe2O3 in the slag is high, it will react with alkaline MgO at high temperature, aggravating the damage of the furnace lining. The influence of slag fluidity on chemical erosion is mainly manifested in: the alkalinity of thin slag is low, the chemical reaction is violent and can cause the molten pool to turn over, which is very easy to increase the heat load of the furnace lining; thick slag will make it difficult to heat up the molten pool and the chemical reaction will proceed slowly, thereby prolonging the high-temperature smelting time and causing damage to the furnace lining.
In addition, chemical erosion is also related to the composition of elements in the molten steel. When smelting steel with high Mn, Si, W or very low carbon content, or steel mixed with a small amount of Pb, Zn and other elements, the erosion of the furnace lining is further aggravated.
The influence of arc radiation or reflection
The arc furnace steelmaking relies on the conversion of electrical energy into thermal energy to melt cold materials and heat the molten pool. This energy conversion and transmission is completed by the arc light of the electric arc. At the same time, the radiant heat or reflected heat of the arc will also act on the furnace dust and soften the refractory material.
Impact of mechanical collision and vibration
If the charging and distribution are unreasonable, there is no broken iron under the heavy material or the right amount of lime is not placed before charging, or the material basket is lifted too high, the furnace bottom and furnace slope may be subjected to the collision, vibration and impact of large pieces of heavy materials to form potholes. If there is no one to direct the loading or the crane does not operate normally, the result will be that the material basket is pulled crookedly and hits the furnace wall, or the steel material is not carefully selected, and serious explosions occur during the melting period, which will reduce the use of equipment for the furnace lining. The smelting workshop is noisy, and the impact of noise waves is another factor in the damage of the furnace lining.
Impact of design parameters
The degree of erosion of the furnace wall is proportional to the product of the arc voltage and the arc power, and inversely proportional to the square of the distance between the electrode and the furnace wall. Therefore, this is also an aspect that our company will consider when designing an electric arc furnace. For example, increasing the inner diameter of the furnace lining, reducing the pole circle diameter and electrode diameter, and improving the plane layout of the electrode are all conducive to improving the service life of the furnace wall.
Influence of operation level
During the smelting process, low-level operation is extremely harmful to the furnace lining. Improper oxygen blowing, the temperature of the oxygen pipe mouth is as high as 2100℃, and the oxygen flame touches the furnace bottom, furnace slope or slag line and other parts, which is very easy to cause direct burn-through. Improper use of the power system is prone to excessively high temperatures in the early stage or temperature rise after the reduction period, which causes serious damage to the refractory materials. Others include: improper implementation of the slag making system, improper control of the chemical composition of the slag being too dilute, etc. Therefore, improving the operation level, eliminating abnormal phenomena, and shortening the smelting time as much as possible are extremely beneficial to extending the service life of the furnace lining. All of our turnkey projects provide detailed local employee training services. In addition, we will also provide 1-2 years of production management services, so that the SME experienced team will accompany the production process to ensure smooth production. If you pursue low professional and technical requirements for personnel, we would recommend the IF+LOD+LRF steelmaking process, which makes up for the weakness of IF’s own lack of refining capacity and retains IF’s high cost-effectiveness, simple deployment and simple operation.
