Refractory brick manufacturers are not well formed. Lets see if this is done?

Clay particle grading refers to the percentage of particles with different sizes in the clay expressed as a percentage.

It determines the reasonable particle size distribution according to the properties of raw materials, production process environment, equipment and various physical indicators required by products. The use of appropriate particle size distribution is not only conducive to the formation of semi-finished products, but also conducive to the drying and sintering of green bodies, and products with high density and strength can be obtained. For shaped refractory products with different density, porosity and strength requirements, it can be obtained by adjusting the slurry particle grade.

The rationality of grain size distribution is not only related to the bulk density, porosity and strength during molding, but also related to the dryness, firing shrinkage and quality of green body. The raw materials with reasonable particle size distribution have uniform green body density after molding, relatively uniform moisture discharge during drying, and are not easy to burst locally, and the firing shrinkage is basically the same. Therefore, reasonable particle size distribution has an important influence on the forming, drying and firing of billets.

1 important influence of reasonable particle grading

1.1 effect of reasonable particle size distribution on forming and blank making

First of all, when the particles in the mud pile up during the molding and blank making of the shaped products, a certain amount of medium particles are usually added to the large particles to fill the gap between the large particles. Finally, the fine powder fills the remaining gap between the large and medium particles, and the gap between the deposits can be further reduced, so as to achieve the most compact accumulation of the mud. In the process of the closest accumulation of mud, all kinds of raw materials, including coarse, medium and fine, are indispensable. If all raw materials are coarse particles, the gap between particles is large, the bonding is poor, the density of green body is low, the porosity is high, and the plasticity is low during forming, so it is difficult to make green body. If all of them are fine particles, although the gap between the particles is small, the bonding is firm, and the porosity is low, the bulk density of the raw material fine powder will be relatively low, which can not meet the required bulk density during forming and blank making, and the strength of the formed green body is not high because there is no coarse particles to play the role of skeleton support. If the multi-component particle grading is considered, the porosity of the obtained slurry will be smaller, but in actual production, with the increase of particle composition, the role of each particle will be significantly weakened due to the continuous reduction of the diameter ratio of each particle, which will bring difficulties to the production process, increase the energy consumption of equipment, and then increase the process cost. Therefore, in the actual production, we can meet the production requirements by using three-component particles.

What is the proportion of coarse, medium and fine particles in the mud? According to the theoretical calculation and experimental results, it can be concluded that the content percentage of three component particles in the mud is 7:1:2. That is to say, during the process of close packing of raw materials, the percentage of coarse-grained materials and fine-grained materials is greater than that of medium grained materials. In this way, the slurry with reasonable particle grading has better plasticity, and can achieve semi-finished products with high density, low porosity and high green body strength.

In the actual production, if the raw material particles are too coarse, a certain amount of fine powder must be added to the mud or the amount of large particles must be reduced, otherwise there will be pockmarked surface, the appearance of the product is not very beautiful, and there will be many open pores, which will increase the apparent porosity and reduce the service performance of the product

If the raw material particle is too fine, a certain amount of coarse-grained raw material must be added to the raw material or the amount of fine powder must be reduced, otherwise the plasticity of the mud will be reduced and it is easy to cause cracks during molding.

1.2 effect of reasonable particle size distribution on product drying

When the slurry can reach close packing during forming and billet making, it is beneficial to the forming and can make the density of semi-finished products reach large, but it will make it difficult to discharge the moisture in the slurry, and dry cracks will occur when the drying temperature is slightly higher; Or a large amount of water can not be discharged completely, resulting in explosion at the initial stage of firing.