The importance of ceramsite grinding to ceramsite production?

Ceramsite is a light, porous, fine particle material with a certain strength, which is often used in the manufacture of concrete, clay products, filling materials, etc. In the production of ceramsite, raw material crushing is an important process. The raw material is ground to make it into powder, which is completed by ceramsite sand grinding mill equipment.

The grinding process is the basic process of unfired ceramsite, which lays the quality foundation of ceramsite, especially the strength foundation, and creates conditions for granulation. The importance of ceramsite grinding process to ceramsite production is mainly reflected in the following aspects:

1. Improve the activity of waste slag and give strength to ceramsite. Unburned ceramsite mainly uses cement and active waste slag as the main source of strength. A considerable part of its strength is generated and endowed by the activity of waste residue, and the addition of a very small amount of cement (or not under autoclaved conditions) is only a supplement. Therefore, the degree of activity of waste slag determines the strength of ceramsite. Grinding is to stimulate the activity of waste slag by physical means, improve its gelling property, and increase the strength of ceramsite. The activator belongs to the chemical activation, and it must cooperate with the physical grinding activation to play a better role. Both are indispensable. Without the grinding process, the activity of the waste residue is only 30% to 40%. After the grinding and activation treatment, its activity can be increased to 80% to 100%. Therefore, grinding plays a key role in the strength of ceramsite. So, why can grinding improve the activity of waste residue?

① Break the hard vitreous body of active waste residue, especially fly ash. Grinding makes the vitreous body crack, roughen or pulverize, so that the silicon-aluminum components closed in the vitreous body are easy to dissolve, and the active components are easy to enter. In this way, the silica-alumina component is more likely to be in contact with the activator, resulting in a reaction excitation, so that the silica-alumina component is more converted into silicate and aluminate, and produces a gelation similar to cement to replace cement. Without grinding, due to the sealing effect of the vitreous body of waste slag, the activator is not easy to work, and the silicon and aluminum components are also difficult to dissolve.

②After grinding, the particle size becomes smaller, which increases the specific surface area of the active waste residue, exposes and produces many new surfaces, and increases the contact area between the activator and silicon-aluminum, which promotes the activation reaction. After grinding, a large particle may become hundreds, thousands or even tens of thousands of small particles, and the surface area increases many times, and the activator can react more with the active waste residue on these new surfaces. In addition, the smaller the particle becomes, the shorter the distance from the surface to the center of the particle, the easier it is for the activator to enter the interior and center of the waste residue particle to react with it, and the reaction will be more thorough.

③ During the grinding process, the activator and waste residue are mixed more uniformly, which increases their contact opportunities and expands their contact area, and can also promote the chemical activation of waste residue.

④In the grinding process, the friction heat is very high, which can increase the temperature of the material and make the activity The waste slag produces thermal excitation, which can also promote the activation of the waste slag.

2. After the material is finely ground, the granulation quality is greatly improved. The grinding process is not only the grinding waste residue, but the mixed grinding of all materials. After grinding, the fineness of the waste residue is greatly improved and becomes finer. The practice of granulation has proved that the finer the material is, the higher the granulation quality is, and the higher the granulation quality, the lower the cost of ceramsite, and the better the overall quality of ceramsite. The material without grinding has large particle size and poor cohesiveness. After granulation, the material is loose and the compactness is not enough. This makes the strength of the ceramsite ball billet very poor, and it will be broken in a large amount during the transportation and stacking process after it is released from the plate, and the yield of the finished product is very low, resulting in a decrease in output and an increase in the cost of ceramsite. After grinding, the granulation is dense, the surface of the billet is smooth and beautiful, and it is not easy to break, which improves the yield. At the same time, due to the good initial strength of the ceramsite ball blank, it can also increase the later strength, reduce the capillary porosity of the ceramsite, and correspondingly reduce the water absorption rate, and improve the water absorption resistance of the ceramsite. Compared with the ceramsite produced by grinding materials, the quality of ceramsite produced by grinding materials is one grade lower. To sum up, grinding is of decisive importance to the production of unfired ceramsite, which must not be underestimated.

3. Technical requirements of the grinding process The purpose of grinding is to make the particle size smaller and the material finer. In principle, finer materials are better, but if the grinding is too fine, it will increase power consumption and grinding labor costs, resulting in an increase in the cost of ceramsite, which is not cost-effective. Therefore, the fineness of grinding should not only meet the technical requirements of use, but also not greatly increase power consumption and other costs. Enough should be enough, not the finer the better. The specific grinding technical requirements are as follows:

① Grinding and sieve allowance If the fineness of grinding is characterized by the sieve allowance, it should be controlled at 0.08 square hole sieve, the sieve allowance is less than 3%; the national standard for the sieve allowance of general cement is less than 10%, and most cement plants are less than 8%. A few factories are less than 5%. The grinding fineness of the ceramsite mixture is finer, which belongs to high-fine grinding, and it should be less than 3%. If there is no condition, the mill cannot meet this requirement, at least it should be controlled at less than 8%.

②Grinding specific surface area The larger the specific surface area is, the better the activation reaction will be. Therefore, the specific surface area of grinding should be as large as possible. At present, the specific surface area of cement grinding is about 300mz/kg, and the specific surface area of high-fine cement is about 320-350mz/kg. The specific surface area of the ceramsite mixture should be equivalent to high-fine cement or slightly finer than cement, and it is best to control it at 350-400m2/kg. It is best to have 1/4 of the active waste residue grind to a fineness of 400-600mz/kg, and ultra-fine grinding can be used.

③ Grinding particle size distribution The particle size of the grinding active waste residue and cement should have a reasonable gradation. After the mixed material is ground, the particles smaller than 60tLm should be greater than 70%, the particles of 10-301um should be larger than soH, and the particles smaller than lOUm should be larger than 30%. Particles smaller than 5 μm should be greater than 10%.