Key Technologies：Large-scale Casting Door Block with Ceramic Glaze for Coke Oven

1. R&D Background

The traditional design of coke oven door brick mostly uses cordierite, floating beads, clay as the main material of small brick manufactured by press machine, the working face is usually not glazed, and because of the small dimensions, the overall stability of the furnace door is insufficient, during in the use process, tar, graphite and other harmful substances are easy to penetrate into the brick body, thus reducing the comprehensive physical properties of the furnace door brick. In addition, it is easy to form a carbon deposit layer on the surface of this kind of brick, which directly affects the tightness of the furnace door. The phenomenon of "smoke escaping and gas leaking" occurs frequently, which brings great environmental protection pressure to Coking enterprises. At the same time, due to long-term thermal shock, chemical erosion and mechanical shock, the service life of furnace door brick is shortened, and the use and maintenance costs of Coking customers are correspondingly increased. Obviously, the high-performance furnace door brick should have good thermal shock stability, anti-permeability, anti-corrosion and anti-carbon deposition, meanwhile, it should have both energy-saving and environmental protection requirements and pay attention to economic benefits.

2. Technological Innovation

2.1 Forming and firing technology of extra-large volume special furnace door brick

During the production process of forming and firing, it is difficult to realize the super volume special furnace door brick. Through long-time process exploration and repeated tests, Yixing Dingshan Refractory Material finally developed the key technology of one-time casting and forming of super volume special furnace door brick, and found out the corresponding firing technology.

Taking the 6-meters coke oven as an example, only five blocks are needed to assemble a complete furnace door, which greatly reduces the brick seam on the working face of the furnace door, improves the overall tightness of the furnace door, effectively avoids the phenomenon of ‘smoke escaping and gas leaking’, and promotes the Environmental Friendly Production of the Coking enterprise.

2.2 Glazing and firing technology of high temperature ceramic glaze on the surface of oversized furnace door brick

In the production process of coke oven, harmful substances such as tar, graphite and so on penetrate and erode the furnace door brick and the problem of surface carbon. Yixing Dingshan Refractory Material organized technical force to cooperate with the R&D team of Wuhan University of science and technology to develop high temperature and low expansion ceramic glaze.

The glaze can not only withstand the environment of 1,300 ℃ without blistering, flying or falling off, but also keep the glaze smooth. At the same time, the expansion coefficient of the glaze layer is basically close to the expansion coefficient of the brick body, so that the thermal expansion and contraction rate of the brick body and the glaze layer are basically the same, so that the brick body and the glaze layer are not cracked or falling off, so as to ensure the overall consistency of the glaze layer and the brick body, and realize the work table of the furnace door brick. The glaze surface has high density and smoothness, so as to effectively avoid the infiltration and erosion of harmful substances on the furnace door brick and the deposited carbon layer.

The technology of high temperature ceramic glaze is to spray the ceramic glaze on the surface of the unglazed ware body, and form a uniform ceramic glaze on the surface of the furnace door brick after high temperature firing. In the long-term use of the coke oven door, the glaze and the brick body are closely combined without falling off and melting under high temperature. It can make the working face of the furnace door brick cover the smooth ceramic glaze for a long time. The existing common technology is to spray organic or inorganic coating on the surface of the brick in the cold state, and the appearance of such furnace door brick products seems to be the same attractive before they are put into use, but the coating will burn off quickly in case of high temperature environment, at this time, the working face does not have the ability to resist the penetration and erosion of harmful substances, nor can it effectively solve the problem of carbon depositing on the surface of the furnace door brick. Yixing Dingshan Refractory Material’s furnace door brick products, which use the high temperature ceramic glaze technology, are covered with a uniform ceramic glaze all the time after being put into use, which greatly reduces the work of carbon removal in the daily production of Coking.

2.3 Key technologies to significantly improve thermal shock stability

In the process of coke oven production, the key factor affecting the service life of the brick is whether the brick can withstand the rapid change of temperature due to the frequent opening and closing of the door. The R & D team of Yixing Dingshan Refractory Material has finally determined the material formula of the new furnace door brick products by using the Micro Pore Theory and the Transformation Toughening Principle, through systematic research, analysis, comparison and selection. Through the inspection of professional organizations, it is found that after 120 times of water cooling at 1100 ℃, the test block is intact and does not crack, and the strength retention rate is more than 80%.