Excellent Performance of Self-Baking Carbon Bricks in the Calcium Carbide Furnaces

In addition to the advantages of ordinary carbonaceous linings, this type of furnace lining material also has the characteristics of high joint strength. In the process of using Self-Baking Carbon Bricks, it gradually “self-baked” into a dense and solid whole, so the service life is increased by 1 ~ 3 times than that of high alumina bricks or clay refractory bricks lining.

Self-Baking Carbon Brick
Self-Baking Carbon Brick

Self-Baking Carbon Bricks Used in the Calcium Carbide Furnaces

A calcium carbide plant uses Self-Baking Carbon Bricks as the lining material, and has been in normal production for more than five consecutive years. After the furnace was shut down as planned, the site inspection found that the gap between the self-baking carbon bricks had completely “healed” and was not easily noticeable. The entire furnace lining forms a dense and solid whole, and the self-baked carbon bricks below the furnace bottom slag mouth and the furnace bottom are basically not eroded, and the inner diameter of the furnace bottom is only increased by 2 cm compared with the value when the furnace is completed.

In order to further analyze the performance of this new type of furnace lining material, samples were taken on the inside of the upper part of the furnace bottom and the inside and outside of the lower part of the furnace bottom, and a comprehensive geographical performance test was performed. It was found that the performance of the self-baking carbon bricks on the inner side of the furnace floor was better than that of the bottom layer. This shows that the part of the self-baked carbon brick in which the molten iron and slag directly contact is superior to the part in which the direct contact is not performed.

From this, we can get enlightenment: In the process of using self-baking carbon brick furnace lining, it has been in contact with molten iron and slag for a long time, withstanding high temperature (1300 ~ 1500 ℃) and metal as catalyst. The excellent properties unique to this furnace lining material. Self-baking carbon bricks linings produced pyrolytic carbon during long-term use. This is the first reason for its excellent performance. This pyrolytic carbon can be seen everywhere in each sample.

Carbon Refractory Bricks
Carbon Refractory Bricks

Three Excellent Performance of Self-Baking Carbon Bricks in the Calcium Carbide Furnaces

In the furnace and in the production process, the heat is transferred from the inside to the outside. The asphalt binder on the inside surface is first coked to form a porous structure. When heat is gradually transferred to the outside, the temperature of the inner secondary surface immediately adjacent to the inner surface also gradually increases, and the asphalt binder there generates a large amount of carbon-containing volatiles. Since the adhesive on the outer side has not been volatilized, either in a molten state or in a solid state, the resistance to the above volatiles is extremely great. Therefore, a large amount of volatiles can only diffuse into the porous structure on the inner surface and crack at a suitable temperature and pressure. As a result, pyrolytic carbon is deposited on the inside of the coke particles on the inner surface and on the side walls of the pores between the coke particles. This increases both strength and porosity. This process gradually develops from the inside to the outside of the furnace lining. The closer to the inner surface of the furnace lining, the longer the deposition time and the denser the texture. Therefore, the compressive strength of the inner side of the furnace lining is higher than that of the outer side, and the porosity of the inner side is also smaller than that of the outer side.

The second reason for the excellent performance of self-baking carbon bricks are those they are gradually graphitized during use, so they have good thermal conductivity and good corrosion resistance, which greatly increases the service life of the furnace lining. Its graphitized Chengdu is close to the graphitized electrode, and the part near the molten iron is higher than the part farther away. This is due to the fact that some metal elements act as catalysts in the ore heating furnace and play a catalytic role. It can be seen that the catalytic effect of metal catalysts in the graphitization of carbon is very obvious. Secondly, although the temperature of the molten iron is not too high, the time that the self-baking carbon brick furnace lining has experienced at such a temperature (up to five years), the carbon can also be graphitized under low temperature and long time conditions.

The self-baking carbon bricks form a metal / carbon composite structure during use. This is the third reason for excellent performance. The self-baked carbon bricks furnace lining has a small resistivity, which is above 60Ω · mm2 / m. The true specific gravity and false specific gravity are very high, and the porosity is very low. The reason is that a large amount of iron, manganese and other metal elements are infiltrated into the furnace lining. Self-baking carbon bricks infiltrate a large amount of molten iron into the porous structure formed by “self-baking” during use, thereby changing their physical and chemical properties. The metal / carbon composite structure formed in this way (similar to electric carbon products) has a dense texture and high strength (one to three times higher compressive strength than graphite electrodes), which is beneficial to the extension of the furnace lining life.

RS Carbon Bricks for Sale
RS Carbon Bricks for Sale

Long Life of the Self-Baking Carbon Brick Furnace Lining

Another important factor of long life is that the self-baking carbon bricks furnace lining is resistant to erosion, and the joints left in the furnace are not obvious. It is precisely due to the displacement of the solid particles when the asphalt binder is melted, the coking-pyrolysis of asphalt, and the infiltration of molten iron into the joint to form a metal / carbon composite structure, which all “heal” the original joint. Thus, the entire furnace lining is integrated, which effectively prevents the ferrosilicon from penetrating and damaging the furnace lining.

Self-Baking Carbon Bricks Furnace Lining

According to the analysis of the sample of the self-baking carbon brick furnace lining,

  • Self-baking carbon brick furnace lining produced pyrolytic carbon during long-term production
  • With graphite structure
  • Form a metal / carbon composite structure
  • The entire furnace lining is integrated

It is these structural characteristics that make the new furnace lining material of self-baking carbon bricks resistant to corrosion and have a long life. Welcome to consult Rongsheng refractory manufacturers, we will provide you with high quality refractory products and services. Please contact us.