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The ferroalloy company of a large steel company uses the electric silicon thermal method to produce the lining of medium, low and micro carbon ferrochrome electric furnaces. It used M-1 magnesia bricks and high matrix magnesia bricks, but its life span has not exceeded the 100-day mark. After the reason analysis, it is found that there are many factors affecting the service life of the refractory material of the blast furnace, and the three factors of the quality, construction and oven of the refractory for the lining are not to be underestimated, as follows: Shown.
1, the influence of the diameter of the heart circle
The diameter of the center circle is an important process parameter for the electric furnace. When the arc temperature of the electrode is above 3000 °C, if the size is too small, the power density of the center circle will be too large, and the heat of the high temperature is too concentrated in the circle of the center of the circle, so that the temperature is too high, the bottom of the furnace is eroded, the consumption is fast, and the life of the lining is shortened. If the size is too large, the power of the center of the circle will be low, the temperature at the edge of the molten pool will be too high, the slag iron will intensify the erosion of the furnace wall, the wall of the furnace will become thinner, and the burning of the furnace wall will occur, and the life of the lining will also become shorter. . Therefore, the proper diameter of the center circle can effectively reduce the temperature in the center of the circle and reduce the erosion of the bottom of the furnace by high temperature heat, which is the main factor affecting the service life of the furnace lining.
2, the influence of the diameter of the furnace shell
The furnace shell diameter is also the main process parameter of the electric furnace. Whether the parameter selection is reasonable and whether it matches the polar circle parameters not only affects the technical indicators of production, but also affects the service life of the lining. If the diameter of the shell and the circle diameter of the pole, the wall distance and the thickness of the furnace wall, and the consumption of the furnace wall and the bottom of the furnace are matched, the life of the lining will be extended accordingly; if the diameter of the shell does not match the diameter of the core circle, If the diameter of the furnace shell is too large, not only the refractory material is wasted and the furnace is affected, but if the diameter of the furnace shell is too small, the furnace wall is too thin and not resistant to erosion, and the life of the lining is also shortened accordingly. This is an important factor in the short service life of the lining.
3. Influence of secondary voltage on furnace lining
The secondary voltage is another important process parameter for the electric furnace. The secondary voltage should be matched to the diameter of the pole circle to extend the life of the lining. When the diameter of the center circle is constant, when the secondary voltage used is low, the arc of the electrode is short, the depth is deep, and the bottom of the furnace is close to the bottom of the furnace, so that the temperature of the bottom of the furnace is too high, and the heat of the electrode arc is on the bottom of the furnace. The erosion effect is increased, so that the bottom of the furnace forms a "pot bottom" and consumes too much. On the contrary, the temperature at the bottom of the furnace is low, the temperature of the slag is high, and the excessively high temperature makes the slag fluidity increase, the erosion of the furnace wall is intensified, the furnace wall is thinned, and the furnace wall burning accident is easily caused, which affects the life of the lining. Because the secondary voltage is relatively stable relative to a certain smelting quality, the impact on the lining is relatively stable.
4, the impact of slag basicity
When producing medium and low carbon ferrochrome, the slag basicity is constant in terms of process, but due to the change of raw materials, the influence of slag basicity on the lining is present. In order to reduce the excessive penetration of SiO2 into the bottom of the furnace, a low melting point phase is formed to reduce the high temperature performance of the furnace bottom, and the life of the furnace lining is shortened, and the alkalinity of the slag is adjusted in time according to the change of each furnace. The production process requires an alkalinity of more than 1.8, which meets the requirements for the use of ramming, and the chemical erosion of the lining is also small.
5, the impact of ramming performance
The ramming material has low, medium and high temperature performance. The low temperature material has good initial sinterability, but the long-term use has poor high temperature resistance; the medium temperature material has good sinterability and high temperature resistance; the high temperature material has poor sinterability, but High temperature resistance. Comprehensive consideration, Sinosteel Jitie has been using medium temperature ramming material. In recent years, the lining life has been between 220 and 251 days.
6, furnace lining life histogram
The initial sintering of the lining is not good, the high temperature resistance is poor, the sintering capacity in the middle and late stages of the lining is excessive, and the high temperature resistance of the lining is insufficient. Therefore, the high temperature resistance of the lining is realized by selecting materials with different properties.
In daily operation, its maintenance and operation are important factors affecting the service life of the submerged arc furnace. After re-replacement of the lining material, the use of magnesium ramming material to build the lining, so that the life of the lining reached 119 days from dozens of days, breaking through the 100-day mark, is the first in the country, so that the ramming material in the field of ferroalloys widely used. In the 10 years of using the ramming lining, the lining life was up to 251 days. The article will discuss the use of composite furnace bottom to extend the life of medium and low carbon ferrochrome electric furnace lining.
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