Reasonable particle grading is crucial to the molding of refractory bricks. In the molding process of shaped products, the particles in the mud are usually dominated by large particles, a certain amount of medium particles are added to fill the gaps between the large particles, and finally the remaining gaps are filled with fine powder to achieve the most compact stacking state. Reasonable particle grading can make the mud reach the best stacking density and avoid problems such as excessive pores, low density, and poor plasticity in the blank.
Specifically, the ratio of coarse, medium, and fine particles in the mud should be 7:1:2. In actual production, if the particles are too coarse, it is necessary to add an appropriate amount of fine powder or reduce the amount of large particles to avoid the appearance of pockmarks and open pores on the surface of the blank, affecting the appearance and performance of the finished product. On the contrary, if the particles are too fine, it is necessary to add coarse particles or reduce fine powder to improve the plasticity of the mud and avoid cracks during molding.
Reasonable particle grading also affects the drying and firing of refractory bricks. During the drying process, although a dense green body is conducive to increasing density, it is also easy to cause difficulty in discharging moisture, which in turn causes cracks during drying or bursting in the early stage of firing. In addition, the particle grading also has a significant effect on the shrinkage during firing. The firing shrinkage of fine powder is greater than that of coarse particles. Too fine mud tends to shrink too much during firing, while too coarse does not shrink enough, resulting in uneven shrinkage.
To ensure the rationality and stability of the particle grading, the raw materials must first be crushed to a suitable particle size, and the cone crusher and vibrating screen must be kept in stable operation to prevent particle segregation. The fluidity of the crushed material in the silo must also be controlled to avoid uneven particle distribution.
In short, reasonable particle grading is crucial for the production of alkaline shaped refractory bricks. By optimizing the particle grading of the mud, the density and appearance quality of the green body can be improved, the qualified rate of drying and firing can be ensured, and high-quality refractory products can be obtained.
