Ferroalloy furnace: a way to prevent carbon furnace lining failure

Carbon lining is the material of choice for most ferroalloy linings. However, as the capacity of submerged arc furnaces continues to increase, the early failure of the lining is a very prominent problem. This technology uses a relatively simple method to solve the problem that has long plagued the industry.

Inventory the currently used carbon furnace lining masonry methods, nothing more than these three: carbon brick seamless method, carbon brick wide seam method, cold ramming and paste integral ramming method.

These three methods all have their own disadvantages and weaknesses. The carbon brick seamless method is actually unable to achieve true seamlessness. The molten iron can infiltrate the bottom of the carbon brick along the crack of the brick and float the carbon brick and cause the entire furnace lining to be scrapped. The carbon brick wide seam method processes the sides of the carbon brick into a ring-shaped groove, leaving a gap of about 50mm when building the furnace, and fill the gap with cold ramming;

Its disadvantage is that the structure of the wide seam part is relatively loose, unlike the carbon brick that is made into a dense structure through high pressure by a press, and is resistant to corrosion by hot metal, so the wide seam part will be eroded early in use, and the molten iron will quickly reach the carbon. The bottom of the brick floats up, causing failure. Because of the loose lining structure formed by the cold ramming and paste ramming method, the performance is not as good as that of carbon bricks and the service life is very short.

After long-term exploration and research, the author has combined the advantages of the three furnace building methods, using the hot-melt property of carbon paste, that is, the paste remains solid at room temperature, melts at high temperature and can be fused, and finally becomes graphitized. The characteristics of solid state, invented a furnace construction method to prevent the early failure of the furnace lining, thereby prolonging the life of the furnace lining, and overcome the problems that have plagued the industry for a long time! This method has obtained the national utility model patent authorization.

This method is based on the seamless method of carbon bricks, and special treatment is carried out on the weak part of the furnace lining-brick joints, thereby solving the problem of brick joints. Brick seams are divided into vertical seams and flat seams.

1. Special treatment of vertical seam of brick

The standing seam treatment method is to cut two inverted dovetail seal grooves around the carbon bricks, and then fill them with a special low-expansion coarse seam paste to make the carbon bricks a pre-baked matrix and self-baked paste Composite carbon brick composed of an endless belt of materials.

After the submerged arc furnace lining is constructed according to the seamless masonry method, the electric furnace is put into use. When the temperature rises, the self-baking paste pre-installed in the carbon brick inverted dovetail tank will melt, fuse, roast and solidify. The standing seams of adjacent carbon bricks are sealed together, which is equivalent to a sealing ring in a mechanical part, which prevents the penetration of molten iron. At the same time, since it is inside the carbon brick, the molten iron will not wash it out, so its the loose structure formed by the paste can also meet actual needs. The connection diagram between the self-baking carbon calcined body and the carbon brick is shown in Figure.

2. Special treatment of brick flat seam

The general design of the furnace lining is 3 layers of carbon bricks, that is, there are two flat seams, and the arrangement of each layer of carbon bricks is staggered by 45° from the lower layer. Inverted dovetail grooves that are wider and shallower than the side grooves are processed on the joint surfaces of the upper and lower carbon bricks, and then filled with the self-baking paste together with the side grooves, and tamped and ground.

When the electric furnace is put into production after the masonry is completed, these flat grooves form a flat prismatic mesh, and the intersections of the upper and lower grooves are fused together, and the upper and lower layers of carbon bricks are joined together through this prismatic mesh. In the future, even if molten iron penetrates to the bottom of the carbon brick, it will not float the carbon brick. The three-dimensional viewof the self-baked paste after sintering is shown in Figure 2, and the three-dimensional schematic diagram of the upper and lower carbon bricks is shown in Figure. 

Through the different treatments of vertical seams and flat seams, the carbon bricks used to form the furnace lining, including wall bricks and taphole bricks, are tightly connected into a whole, which prevents iron penetration, which perfectly solves the problem of the industry. 

This method is very simple to implement and very effective. It is worthy of attention and adoption by colleagues in the industry. I believe that the promotion and application of this method will greatly extend the life of the furnace lining, greatly reduce the production cost, and raise the lining technology to a new level.