Monolithic Refractories: a comprehensive analysis

Homogeneous refractory materials are mechanical mixtures of refractory materials that act as aggregates, adhesives, metallic materials, or other desirable product properties. The mixing of materials causes physical and chemical reactions during installation and during the molding of prefabricated objects, not during use. Monolithic refractory differs from refractory bricks is that they are not cast or fired before use, although the chemical and physical properties show similar and sometimes better properties. The main advantage of unshaped refractories is that they hardly require high energy requirements to form and preform, thereby saving a lot of labor and energy. Since it has nothing to do with molding or firing, manufacturing and delivery times are shorter, and users need less inventory. Since combustion is not required, a lot of energy is saved and expensive pollution control devices for furnace exhaust gas are not required. On the other hand, monolithic refractories involve the simplified construction of complex structures. Monolithic refractories can be partially repaired without destroying the entire structure, saving materials, time, and labor. Monolithic refractory materials are ideal for installing airtight walls, so they are most suitable for building pressure vessels that operate under high pressure and high temperature.They are easier to install and shorter to complete. Depending on the type of application, monolithic refractories can be applied in various ways.

In the past 20 years, the monolithic refractory industry has undergone a series of developments in the addition of materials and the material composition of bonding systems. In addition, new application methods have helped them replace brick applications in various applications. The following developments have significantly increased the market share of monolithic refractories in various applications:

  • Although plastic refractories have been used for decades, plastic gunning has opened up new applications. In remote areas, the direct application of plastics is usually impossible. In addition, in extremely cold regions, conventional weapons are sometimes not feasible because it is difficult to obtain a normal current of water. Refractories for plastic guns solve these problems by providing good performance and convenience. It also provides quick installation in kilns and rotary kilns, making it easier and more convenient.

  • The development of low-grade and ultra-low-grade cement casting has opened up many previously unexplored applications for monolithic refractories. Its properties are not worse, and in many cases better than those of bricks, which saves the user's time, effort and money. Cement forms with low and very low cement content have been used for blast furnaces, screws and iron pipelines. Applicable in various furnaces, steel and transfer chambers, rotary kilns and trays. It is also used for a wide variety of off-the-shelf and small items such as pocket blocks, pools, boots, slabs, partitions, bowls, and manhole blocks. , various types of flashlights and other similar uses.

  • The use of cementless bonding systems by replacing luminescent calcium cement with sol-gel bonding is another step in the advancement of monolithic refractories. Sol-gel bonding systems produce self-flowing materials, which have significant advantages over low-cement and ultra-low-cement concretes with excellent physical and chemical properties. In addition, they can be installed by pumping, which reduces installation time. The composition does not contain chemically bound water, so the drying and cooking time are greatly reduced.

  • Since the development of cementless pumpable compositions, low cement and ultra low cement compositions have been improved by carefully adjusting the particle size so that they can also be installed by pumping. This pump installation process eliminates some of the problems associated with low and ultra-low cement compositions, thus increasing the application fields of their cement compositions and therefore expanding their application fields.

  • A new type of low cement content castable is formed by applying refractory materials (such as alumina-magnesium spinel) in sintered or cast form. These castables are completely free of SiO2, so they can be used to make ultra-clean steel. In addition, because of their high temperature resistance, they are used in high temperature and high pressure areas.

  • The latest development in this field is the application of low and ultra-low cement-based and cement-free compositions through spray guns or "shot concrete". The process combines gun castables and low-cement refractories, thereby providing convenience for spraying applications that are close to the characteristics of low-cement castable compositions. Although the current application of this technology is limited to a few specific fields, it has great potential in various other applications in the near future.