The core of the physical and chemical indicators of special clay refractory bricks is low porosity, high load softening temperature, and high strength. The technical ideas of research and development mainly include the following aspects:

(1) Selection of raw materials. Special clay bricks are still in the category of clay bricks. The content of Al2O3 is less than 48%, so the main raw material is still coke gemstone, but the coke gemstone must be fully sintered and is mainly made of mullite crystal phase. Also, choose M45 mullite. There are many kinds of M45 mullite, one of which is made of hard clay after appropriate treatment (such as a wet process), and then calcined at a high temperature (greater than 1500 ℃). This raw material is mainly the mullite crystal phase. There is no or a small amount of cristobalite, and the remainder is a glassy phase.

According to the requirements of indicators such as load softening temperature, mullite, sillimanite, and andalusite are introduced.

(2) Appropriate grading and production process. According to the principle of close packing of crystallization chemistry, the raw materials are made of the coarse, medium, fine, and fine multi-stage ingredients, especially the introduction of fine powder or micro powder. Production process parameters such as binder selection, dosage, adding method, matrix homogenization, firing system, and other parameters.

(3) Introduce a sintering agent that is easy to sinter to improve the microporosity of the refractory. This is the characteristic and key to the development of special clay bricks with low porosity and high load softening temperature.

The selected sintering agent is a natural composite three-stone mineral with fine particle size (-200 mesh or -325 mesh). -1300℃ is easy to form a liquid phase, the liquid phase promotes the formation and development of mullite, increases the mullite of the matrix, strengthens the matrix, and at the same time blocks the pores in the material and reduces the porosity of the material.

The technical concept pays attention to the principle of microstructure as a guide. In the selection of main raw materials, coke gemstone, M45 mullite, sillimanite, andalusite or M70 mullite have more mullite phases. There are also three stones in the matrix, and there are special composite types of three stones in the sintering agent. In this way, an enhanced matrix microstructure is achieved.

In addition to the in-situ mullite phase generated by the three-stone minerals at high temperatures, the rest is a SiO2-rich liquid phase. The remaining SiO2 has dual functions: one is to react with Al2O3 to produce secondary mullite; the other is to fill the pores in the material and increase the microporosity, thereby obtaining special clay bricks with low pores and high load softening temperature.