Refractory Bricks

The corundum mullite bricks in the process of grinding

Feb 23,2022

At present, corundum mullite brick is one of the main products of blast furnace ceramic cups. At present, the product still has some quality defects in terms of performance. The main manifestation is that the phenomenon of missing edges and corners in the grinding process of the product is more serious, which affects the product. Masonry quality. Through the improvement of this project, it can be ensured that the product quality qualification rate is increased by 2%, can pass the customer's quality acceptance smoothly, and the quality reputation is improved, and the market share of the product is further increased.

corundum mullite bricks

1.Analysis of the reasons for the lack of edges and corners of corundum mullite bricks in the process of grinding

Corundum mullite bricks have serious missing edges and corners during the grinding process. The analysis reasons are as follows:

1). Hardness. It is generally believed that hardness is an important indicator of the wear resistance of materials. The harder the material, the better the wear resistance, but in the case of large impact and wear, the impact of hardness is not necessarily very large. Refractory bricks are heterogeneous, and the hardness of each part may be different. For refractory bricks containing corundum and silicon carbide, if the bonding strength is sufficient, these high-hardness materials can still resist the abrasion of the refractory bricks when the wear-resistant materials with low hardness are worn out.

2). The mutual solubility of crystal structure and crystal. Materials with a certain specific crystal structure have better wear resistance. For example, cobalt with a close-packed hexagonal structure has a small friction coefficient and is resistant to wear. The wear resistance between metals with poor mutual solubility in metallurgy is also good.

3). Strength. Refractory bricks will encounter a large amount of impact wear during the use process. Therefore, high-strength refractory bricks have strong abrasion resistance.

4). Bulk density. Refractory bricks with large bulk density and low apparent porosity have high abrasion resistance.

5). Temperature. Temperature has an effect on the hardness, mutual solubility and reactivity of the material, and thus indirectly affects the wear resistance of refractory bricks. Generally, as the temperature increases, the mutual solubility and reactivity increase. Refractory bricks are used at high temperatures, and the abrasion resistance at high temperatures is very important.

6). Atmosphere. Similar to the effect of temperature, the atmosphere affects the mutual solubility and reactivity between materials, thereby affecting their wear resistance.

2. Key technology and project implementation content

According to the above factors, the product formula system is modified in a targeted manner: in the production process of the product, through the reasonable particle gradation and the selection and use of high-quality aggregates, the density of the corundum mullite bricks is increased; the firing temperature is optimized to improve the product The physical and chemical properties and abrasion resistance of the product ensure the quality of the later grinding and processing of the product, thereby ensuring the improvement of the quality of the product's pre-masonry.

1). Use high-quality raw materials: bauxite-grade raw materials of better quality and brown corundum raw materials are used as aggregates to ensure the high hardness of the material, increase the toughness of the refractory material, and will not increase the cost.

2). Increase the proportion of brown corundum fine powder in the matrix fine powder, and increase the alumina fine powder at the same time, reduce the porosity of the product after firing, and increase the density of the product.

3). Change the traditional product stacking method and increase the air intake holes of the kiln car stacking to make the firing temperature more uniform.

4). Increase the sintering temperature of the product, so that the product is fully sintered, and the internal materials are fully combined and mutually dissolved.

3. Project implementation plan

1). In combination with the performance requirements of the product, select materials with high body density and hardness, and finally determine that the raw material combination of brown corundum and bauxite is still selected. The hardness of brown corundum is used as the skeleton to provide high strength for the product. In terms of hardness, it is slightly inferior to brown corundum, but it has toughness. It can be wrapped with brown corundum at a slightly lower firing temperature. The combination can meet product performance and economic indicators.

2). Combined with the original formula structure, combined with a small amount of bauxite and brown corundum, supplemented by mullite raw materials and alumina powder, the bricks are formed under high pressure (increasing the body density of the bricks) to form a highly polymerized body. The traditional code kiln method increases the width of hand seams, improves the temperature homogenization performance of the kiln car, determines the appropriate firing temperature, and achieves the effect of mutual dissolution of raw materials, tight bonding, and small pores inside the product.

Corundum mullite bricks use brown corundum combined with bauxite to enhance the anti-wear performance of the product, but it has a certain effect on the softening temperature of the product under high-temperature load, and the proportion of bauxite is not easy to increase.

The amount of alumina powder added is sufficient to control 2a%. Too much alumina powder affects the firing temperature and also reduces the compactness of the brick body.

In the matrix fine powder, it is beneficial to reduce the addition of bauxite raw materials, and the addition ratio can be reduced to 1a% to enhance the hardness of the matrix.

 


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