After the sintering process of refractory high alumina bricks is completed, we have another crucial step, which is the screening of finished products. If you want to screen out the best refractory bricks, you must first be familiar with the qualified screening process.
The entire screening process can be divided into the following parts:
1. Check whether the shape and size of the product meet the requirements of the drawing
Generally, there is a certain allowable range for the positive and negative deviations of the finished product size in the standard, which is called the allowable size deviation. In the standard, there are two ways to stipulate the allowable deviation of the product size:
1. For example, the standard size of the product on the drawing is 200mm, and the allowable deviation of the finished product size is ±2mm. Then, products of 202-198mm are all considered qualified products;
2. If the original drawing is still calculated as 200mm long, the allowable deviation of the finished product size is plus or minus 2%, then 200mm+200mm×2%＝204mm, 200mm-200mm×2%＝196mm finished products are all qualified products.
2. Check the defect status of the product
1. Distortion
The bending deformation that may occur in refractory products during the firing process is called distortion. The regulations on product distortion in the standard are different according to the product appearance quality requirements, grade, impact on masonry quality, and the length of the measured surface of the product.
For example, for ordinary high alumina bricks used in hot blast furnaces, the brick length is less than or equal to 345mm, and the distortion is not more than 1.5mm;
For products with a brick length greater than 345mm, the distortion is not more than 2.0mm.
2. Missing corners and missing edges
Different types of refractory products have clear regulations on the depth of missing corners and missing edges in the standard according to their use conditions, appearance quality requirements and grades. A few types (such as plug bricks) also limit the length of missing edges.
For example, for high-aluminum products used in hot blast furnaces, the length of missing corners (a+b+c) is allowed to be no more than 40mm, and the length of missing edges (e+f+g) is allowed to be no more than 50mm.
3. Melt Hole
Melted hole refers to the pit caused by the melting of low-melting materials on the brick surface. In the standard, there are strict controls on the surface (working surface) of refractory products that are in direct contact with the melt.
For example, the diameter of the melt hole of high-aluminum products for hot blast furnaces is stipulated as no more than 6mm for the working surface and no more than 8mm for the non-working surface;
The diameter of the melt hole of high alumina bricks for ladle is stipulated as no more than 5mm and 7mm respectively.
4. Crack
The crack that can be seen from the surface of the product when a part of the organizational structure of the product is split is called a crack. The crack regulations for various refractory products are also different according to their use conditions. For ordinary refractory materials, cracks with a width of less than 0.2mm are generally not restricted;
However, cracks with a width of more than 1mm are not allowed.
Therefore, a qualified refractory brick is not delivered to customers until it has gone through so many strict screenings to ensure that customers can get the best effect when using it.
