The electric arc furnace roof is an important element of the electric arc furnace, and the working conditions in the smelting process are very harsh. For example, continuous high temperature, mechanical vibration, rapid cold and heat, slag erosion, dust particle scouring, acid gas corrosion, etc., all cause damage to it. Especially its triangle area will be damaged earlier than the surrounding parts, often also because the triangle area resistant material used to the limit to cause the overall top of the furnace resistant material down the line. If a material is used to make the roof, and if it is damaged in the triangle area, it affects the whole roof, the outer part of the resistant material will be wasted. Therefore, in this case, the composite electric furnace roof came into being. In other words, the triangle part is made of high purity material, and the peripheral part is made of slightly lower grade material composite. In this way, the furnace top triangle area and the peripheral life can be synchronized. However, this composite roof in the production process and there is a great difficulty: when more than two kinds of materials to make the roof prefabricated parts, in forming either high-grade materials and low-grade materials easily mixed, reducing the grade of the triangle resistant materials, so as not to get the desired effect; either high-grade materials and low-grade materials between the interface is not handled well, resulting in the interface at the two materials delamination, cracking, shedding, etc.. Both of these two situations restrict the service life of composite furnace top prefabricated parts.
　　
In order to solve the above difficulties in manufacturing composite roof precast, Rongda designed and developed a composite roof structure with snap-in type, so as to meet the mixed precast of many grades of materials.
　　
The triangle area is the key part of the furnace top, the working environment is the most severe, and it is necessary to ensure the material has high purity, so this part is required to be prefabricated separately in advance. After the molding and maintenance expires, the mold is removed, and then the peripheral part is poured around it after the prefabricated part gains enough strength; the peripheral part is divided into two parts, the lower peripheral part and the upper peripheral part, according to the use environment and the degree of vulnerability, the lower peripheral part is the hot surface, close to the steel liquid surface, and the material grade is second only to the central triangle, the upper peripheral part is relatively cold surface, and there is basically no abnormality in the use environment.
　　
The above-mentioned composite snap-type furnace top prefabricated parts, the technical key points are: the triangle area is separately prefabricated, the thickness (height) is higher than the peripheral part; the upper part of the triangle area is equipped with three points of uniform distribution of the card holder to prevent frequent use of the fall off; the part of the triangle area and the peripheral contact with the vertical direction into 3 ° ~ 5 ° angle; the contact surface of the triangle area and the periphery is uniformly distributed a number of auxiliary card holder holes to prevent the fall off; card holder holes and horizontal The peripheral material is divided into upper and lower parts, which are casted in the same batch and at one time. The advantages of the technology are: while ensuring the service life of the top prefabricated parts, effectively reducing the dependence of the electric arc furnace top on the high energy consumption and high pollution way of preparing raw materials, and reducing the cost of the top prefabricated parts; effectively solving the problems of the composite structure of the electric arc furnace top prefabricated parts is not tight, and the triangle area is easy to fall off in advance; realizing the idea of synchronizing the life of the triangle area and the peripheral part of the electric arc furnace top.

Figure 1 Snap-in composite electric furnace top prefabricated products

Figure two is using the card position composite electric furnace top prefabricated parts

Figure 3 Snap-in composite electric furnace roof triangle shape schematic diagram

Fig.4 Schematic diagram of the periphery of the top of the composite electric furnace after forming

(Expert Group of Beijing United Rongda Engineering Materials Co., Ltd.)