With the development of new dry-process cement production technology, corresponding refractory materials have also made considerable progress. In addition to breakthroughs in conventional refractory bricks, the performance of refractory castables has become more and more perfect, and is widely used in unshaped parts in kilns. As we all know, refractory castable is a kind of amorphous refractory without calcining. It is made up of refractory aggregate, refractory powder and cement in a certain proportion; it has good fluidity after adding water and stirring during construction. Then it is formed and cured (to be baked according to a certain temperature system) to make it condense and harden. Its use characteristics are as follows: First, the masonry structure has fewer joints, strong integrity, and good sealing performance. It can avoid the infiltration of clinker powder during application and operation; second, it is easy to anchor and easy to construct, which is beneficial to improve masonry efficiency and Masonry quality; The third is that the raw materials are widely used, which is convenient for comprehensive utilization of resources, and the delivery time is short, which can reduce the inventory and related expenses accordingly. Based on these advantages, the application ratio of refractory castables in the cement firing system has been increasing year by year. Taking the 5000t/d new dry process kiln as an example, the use ratio of refractory castables and refractory bricks has reached 1:1.
With the gradual expansion of its application, its life cycle has become the most concerned issue of all owners. In order to ensure the life cycle of the design requirements, the following aspects should be achieved: first, a strong manufacturer should be selected to ensure its own quality; second, reasonable selection and configuration should be carried out according to the use environment; third, construction There must be a reasonable construction plan and strict construction process control measures, including proportioning control, molding quality control and reasonable maintenance, heating system control and so on.
In layman’s terms, it is a kind of high temperature resistant concrete, so it also conforms to the theory of concrete. For example, the amount of water added is the fundamental reason for controlling whether it can achieve the design strength. However, driven by profits, some construction parties will add a lot of water to the castable in order to speed up the construction progress during the construction of refractory castables, resulting in the use of the kiln refractory lining after the construction is much lower than the design requirements , Even after half a year of use, serious problems have occurred and must be overhauled (and for well-constructed refractory castables, there is no need for overhaul after 3 to 5 years of use). We know that refractory investment accounts for a small proportion of the entire plant investment (about 2% to 4%), but its impact on the future operation of the entire system is very large. The loss due to a refractory lining accident for a day of stopping can be as little as hundreds of thousands or even millions. Therefore, ensuring the high operating rate of the firing system can achieve the high-quality, high-yield and low-consumption operation of the system. Therefore, the construction process control is particularly important. Usually we should strictly follow the following regulations.
First, the amount of water added to the castable should be strictly controlled in accordance with the instructions for use, and should not exceed the limit. On the premise of ensuring the construction performance, the amount of water added should be less than more.
Second, the mixing time of the castable is not less than 5min. When operating, use a compulsory mixer. When mixing, dry mix first, and then add 80% of the amount of water to stir. Then, depending on the degree of dryness and wetness, slowly add the remaining water and stir until Obtain a suitable working consistency.
Third, the pouring material poured into the mold frame should be immediately stratified with a vibrating rod. The height of each layer should not be greater than 300mm, and the vibration spacing should be 250mm. When vibrating, try to avoid touching the anchors and not damaging the heat insulation. Do not vibrate and re-vibrate on the same part for a long time. After seeing the reflow of the castable surface, the vibrating rod should be slowly withdrawn to avoid segregation and voids in the castable layer.
Fourth, when pouring a large area, the construction should be divided into blocks. The pouring area of each block should be about 1.5m². The expansion joints should be set according to the design and should not be omitted. The expansion joints should be set in the middle of the anchor interval.
