Introduction to Common Refractory Bricks From Material Composition (1)

Xinhongji Refractory mainly explains these common refractory bricks carefully from the material composition.

1. Silicon Refractories

Silicon refractories are refractory materials with silicon dioxide as the main component. Usually, the silica content is not less than 94%. It can be shaped or unshaped refractory material. The main variety is silica brick. Using silica as raw material and firing at 1350-1430°C, the main phases in silica bricks are transformed into tridymite, cristobalite, and glass. The true density must be within the range of 2.31~2.42 grams per cubic centimeter. It has the advantages of high thermal conductivity and load softening point and strong resistance to acid slag erosion. Silicon products are acidic refractory materials, which have strong resistance to acidic slag, but are easily eroded by alkaline slag and easily damaged by oxides such as potassium oxide and sodium oxide, but are resistant to oxidation such as ferrous oxide and iron oxide. The material has good resistance. Silicon bricks, a typical product in silicon products, have the characteristics of high load deformation temperature, and their load softening temperature is close to the melting point of phosphorus quartz and cristobalite (1670°C, 1713°C); silica brick masonry has good air tightness and structure Intensity, the biggest disadvantage is the low thermal shock resistance. Silica bricks are mainly used as structural materials for coke ovens, glass melting furnaces, acid steelmaking furnaces, and other thermal equipment.

2. Aluminum Silicate Refractories

Aluminum silicate refractories refer to refractory materials with Al2O3 and SiO2 as main components. Generally, it is made of natural raw materials such as pyrophyllite, refractory clay, high alumina bauxite, sillimanite group minerals, or artificial synthetic materials such as corundum and mullite. According to the Al2O3 content in the product (15%~30%, 30%~48%, >48%), it can be divided into semi-silicon, clay, and high alumina products. The refractory material has the advantages of being lightweight, thermal stable, and having good thermal insulation performance, but its deformation temperature is 1400°C. Therefore, aluminosilicate refractories are generally used as insulation materials in the metallurgical industry, not for working layers.

(1) Low-creep clay bricks. The performance of this clay refractory brick and the corresponding clay refractory castable is a low creep rate, and the volume is more stable under a high-temperature environment.

(2) Phosphoric acid-impregnated clay bricks. After being impregnated with a phosphoric acid solution, clay bricks have strong resistance to alkaline slag erosion and high compressive strength.

(3) Low-porosity clay bricks, also known as dense clay bricks, pay more attention to porosity during production, increasing the density of clay bricks, and making them compact and compressive.

(4) Lightweight clay bricks are generally used as refractory bricks for heat insulation in industrial kilns. They are light in size, low in density, have many pores, and have good heat insulation effects.

3. High Alumina Refractory Material

High-alumina bricks are higher than clay bricks in terms of performance and use effect, but the price of high-alumina refractory bricks is also higher than that of clay refractory bricks. Various:

(1) Low-creep high-alumina brick is a refractory brick with a low creep rate, strong heat storage capacity, and more stable volume at high temperatures. It has low creep performance with low-creep clay brick.

(2) Anti-flaking high-alumina bricks have strong anti-flaking performance, good alkali corrosion resistance, and stable thermal shock performance. They are generally used in cement rotary kilns.

(3) Phosphate high-alumina bricks, which are very different from phosphoric acid-impregnated clay bricks. Phosphate high-alumina bricks are high-alumina refractory bricks processed with phosphate solution as a binder. Abrasion is better.

(4) Micro-expansion high-alumina bricks. When making high-alumina bricks, a small amount of andalusite and sillimanite powder is added to make the volume of high-alumina bricks slightly expand. In the high-temperature kiln environment, the integrity is better and the slag resistance is enhanced.

(5) Grade 1, 2, and 3 high-alumina bricks. This type of high-alumina brick is determined by the level of aluminum content. The aluminum content of the third-grade high-alumina brick is 55%, and the aluminum content of the second-grade high-alumina brick is 65%. %, the aluminum content of first-grade high-alumina bricks is 75%, and the aluminum content of special-grade high-alumina bricks is above 80%. The higher the aluminum content of high-alumina bricks, the more expensive the price of high-alumina bricks will be.

(6) Lightweight high alumina bricks, together with light clay refractory bricks, are used as heat-insulating refractory bricks for kilns, which have a good heat insulation effect and stable thermal shock performance. When purchasing lightweight refractory bricks, if the lightweight clay bricks can meet the conditions of use, there is no need to purchase lightweight high-alumina bricks. The specific purchase of lightweight refractory bricks needs to consider the actual needs.