The classification of Fused Cast AZS Block

Fused cast AZS block is the largest consumption species of fused refractory material at present. Glass erosion resistance is strong, with different composition of the glass can adapt. The product categories of fused cast AZS block are as follows:

1. According to zirconia content,fused cast AZS block is divided into three grades: 33 # AZS, 36 # AZS, 41 # AZS.

In general, with the improvement of zirconium dioxide content, baddeleyite mineral content increased, improved glass erosion resistance and high temperature softening property.

2. By casting method, AZS is divided into four types: ordinary casting (PT), tilted casting (QX), Quasi no shrinkage casting (ZWS), no shrinkage casting (WS).

Cast hole is a scourge of fused cast AZS block. When using the general pouring brick, cast hole will account for a third to half of the brick. In order to reduce or remove the cast hole, often used by pouring casting hole cut off without shrinkage cavity brick, increase the density of fused cast AZS block, enhanced ability to resist erosion.

3. According to production process method, products are divided into oxidation (Y) and reduction method (H) oxidizing atmosphere. Main impurity in fused cast AZS block is Fe3 +, Ti4 +, glass phase seepage temperature is high, greater than 1400 ℃. Reducing atmosphere,  main magazine in AZS is Fe2 +, Ti3 +, more than 1100 ℃, fused cast AZS block is easy to be eroded. Produce stones, stripes and bubble in the glass.

The use performance of Corundum Brick

The use performance of corundum brick refers to the corundum brick has the performance when used in high temperature. Including refractoriness, refractoriness under load, linear change rate, thermal shock resistance, slag resistance, acid resistance, alkali resistance, oxidation resistance, resistance to hydration and CO erosion resistance, etc.

1. Increase the refractoriness.

Refractoriness refers to corundum brick with non-melting performance under resistance to high temperature. Refractoriness is the basis for determining material whether can be used as a refractory brick. The international standardization organization stipulates above 1500 ℃ refractoriness of inorganic non-metallic materials is the refractory material. The significance of refractoriness and melting point is different. Can not take refractoriness as the use of corundum brick temperature. The basic factor of refractoriness to decide is chemical mineral composition and its distribution of corundum brick.

2. Increase the refractoriness under load.

Corundum brick refractoriness under load refers to the products bear constant load deformation temperature under the condition of rise temperature. It shows corundum brick the ability of resistance to high temperature and load effect, to a certain extent, indicates that products in the similar conditions of use case structure strength. The major factors that affect corundum brick refractoriness under load is the chemical mineral composition and microstructure. To improve the purity of raw materials, reduce the content of low melting or flux, increase the molding pressure, made of high density of bricks, can significantly improve products refractoriness under load.

3. Improve the thermal shock resistance

Thermal shock resistance refers to the corundum brick with damage resistance performance to the temperature change rapidly. Generally speaking, the thermal expansion rate of corundum brick is greater, thermal shock resistance is worse.

What are the unique advantages of Sillimanite Brick?

Sillimanite brick is refractory brick made of sillimanite minerals. Commonly using high temperature burning method and mud casting method to product.

Sillimanite brick has five big advantage of using:

1. The application of non-ferrous metal smelting industry

Use silicon carbid, high temperature resistance, big strength, good heat conduction performance, impact resistance, high-temperature indirect heating material, such as strong retort furnace. Distillation furnace tray, aluminium electrolyzer, copper melting furnace lining, furnace zinc powder with arc plate, the thermocouple protection tube, etc.

2. The application of iron and steel industry

The use of silicon carbide corrosion resistance. Thermal shock resistance to wear and tear. Good characteristics of thermal conductivity, for large blast furnace lining to improve the service life.

3. The application of metallurgical mineral processing industry

Silicon carbide hardness is second only to diamond, strong wear resistance, is wear-resisting pipe, the impeller, pump room, cyclone, ore bucket lined with ideal material, its wear resistance is  5 to 20 times than the service life of cast iron,rubber,  is one of the aviation flight track ideal material.

4. The application of building materials ceramic, grinding wheel industry

Using the coefficient of thermal conductivity.The characteristics of thermal radiation, high strength, manufacturing sheet kiln furniture, not only can reduce the capacity of kiln furniture, also improves the loading capacity of the kiln and the product quality, shorten the production cycle, is the ideal indirect materials of ceramic glaze baking sintering.

The Application of Ceramic Fiber Module in Industrial Furnace

Ceramic fiber is a kind of fibrous high temperature resistant material with soft and whippy in the 1970s, it open up a new approach for industrial furnaces and other thermal technology equipment of energy-saving reform. Ceramic fiber as a lightweight, the highly effective refractory insulation materials, has light weight, good thermal insulation performance, convenient to construct, without lining baking and many other advantages, so at present it is the most widely used industrial furnaces lining material. Ceramic fiber has very low thermal conductivity, used for furnace lining to reduce furnace wall cooling, has better energy saving effect. At the same time because of the characteristic of low thermal inertia, makes the temperature control of reheating furnace changes more convenient, so the ceramic fiber (module) as furnace lining widely used in the heating furnace of steel industry.

1. The application of ceramic fiber module in the steel industry: the traditional industrial furnaces refractory lining weight is bigger, furnace heat storage waste is serious, the heat preservation effect is poor, furnace grim temperature is over 100 ℃, furnaces temperature is difficult to precise control. In recent years, industrial furnace refractory lining of the furnace wall used in the design of the whole fiber lining, due to the fiber of low thermal conductivity, low density, light weight, when designing construction of the kiln, all adopt lighter steel support structure, which makes the development of the industrial furnace into the era of “kiln lightweight” kiln. Fiber heat storage is small, to adapt to the rapid heating and cooling mode of operation. Moreover fiber modules can be processed into different products, to adapt to the furnace shell inner wall various shapes. Fiber module has good mechanical vibration and impact resistance, chemical stability is also better, these advantages play an important role to the development of new type kiln.
2. The heat-resistant technology development trend of ceramic fiber module: the main bases of ceramic fiber are Al2O3 and SiO2, common ceramic fiber Al2O3 content is lower, the formation of fiber can not separate out mullite phase, known as: amorphous alumina oxide of ceramic fiber, the using temperature is around 1000 ℃. In recent years, developed a crystalline aluminum oxide ceramic fiber. The Al2O3 content reaches over 72%, melting point is very high, can separate out a homogeneous mullite phase rystal, known as the crystalline aluminum oxide ceramic fiber. The heat resistant temperature can reach 1 600℃.

At present, energy saving, environmental protection, prevent the earth warming has increasingly become the focus of world attention, fuel costs will become the bottleneck of iron and steel industry development.

Industry furnace, especially iron and steel industry furnace, when designing, should adopt ceramic fiber module as furnace lining as far as possible, should try to use maintenance time for the old heating furnace, change the carpet type lining or refractory brick or layer as ceramic fiber module structure, it is also an important measure to realize the sustainable development of iron and steel industry.

The Application of Magnesia in the Refractory Industry

The magnesia made of natural magnesia by one-step or two-step calcination process in a shaft kiln or rotary kiln is called sintered magnesia. The magnesia made of magnesia by melting in an electric arc furnace and then cooling to solid is called fused magnesia. Seawater magnesia is exacted from seawater.

 

Magnesia can also be divided into fused magnesia, intermediate magnesia, high purity magnesia and dead burned magnesia.

 

Dead burned magnesia is made of natural magnesia by firing at high temperature in a shaft kiln. It can be used to produce refractory bricks and monolithic materials for steel smelting in electrical furnaces.

 

Fused magnesia is made of chosen special grade natural magnesia or high purity light burned magnesia particles. It has high purity, large size, dense structure, good slag resistance and good thermal shock resistance. It is a good electronic insulation material and raw material for high grade magnesia brick, magnesia carbon brick and monolithic material.

 

Intermediate magnesia is made of 97% light burned magnesia by ball pressing and high temperature firing in a shaft kiln. It has good degree of sintering and fine crystal. It is used in the production of intermediate magnesia refractories.

 

High purity magnesia is made of natural magnesia by light burning, fine grinding, ball pressing, and ultra-high temperature firing in a shaft kiln.

The raw materials of Refractory Brick and firing methods

Refractory brick has a variety of raw materials, the composition is mainly divide with the six categories: earth, stone, sand, ore, powder and other.

1. Earth: aluminum earth, kaolin earth, clay, diatomaceous earth.
2. Stone: fluorite, kyanite, andalusite, forsterite, vermiculite, mullite, pyrophyllite, chlorite, dolomite, sillimanite, magnesium aluminate spinel, silica.
3. Sand: ceramic sand, zircon sand, quartz sand, magnesia snad.
4. Ore: chrome ore.
5. Powder: metal aluminium powder, silicon powder and silicon metal powder.
6. Other: Asphalt, graphite, phenolic resin, perlite, floating bead, corundum, sulfuric acid silicon, silicon carbide, soluble glass, silica sol, boron carbide, calcium aluminate cement, nitride materials, shale ceramsite, alumina, alumina sol, zirconium oxide, etc.

The firing stages of refractory brick:

1. At room temperature to 200 ℃, the temperature should not be too fast, in case of refractory brick body cracking, in the tunnel kiln firing, the former 4 parking temperature should not exceed 200 ℃.
2. 200 ~ 900℃: the temperature should speed up in the stage, for the organic matter content in the refractory brick and impurities of chemical reactions to conduct. During the period of 600 ~ 900 ℃, should stay stronger oxidation atmosphere in furnace, avoid  the “black heart” refractory waste.
3. 900℃ to the highest firing temperature: in the high temperature stage, should be smooth temperature and steady, continue to maintain the oxidizing atmosphere, make the refractory brick body heated evenly, also need to prevent cracking of refractory brick. Due to above 1100 ℃ high temperature, sintering shrinkage is very strong, shrinkage rate reaches 2-5%, so keep the gentle temperature gradient, eliminate internal stress is very important.
4. Cooling stage: according to the character changes of refractory products in the cooling section, the temperature should be fast cooling above of 800 ~ 1000 ℃ high temperature stage, under 800 ℃, should slow cooling rate, in fact, in the actual production, the cooling speed of actual use will not cause cold cracking risk to refractory products.

The production process of Refractory Materials

The variety quality of refractory materials has a big relationship with production process. The same raw material using different process, can produce need different varieties and quality of products.

The production process of generally block burned into refractory brick:

1. Raw materials

Make different refractory products, need to adopt different chemical mineral composition of raw materials.

Refractory products demand for raw materials are: suitable chemical mineral composition and content of impurities in raw material: fewer and uniform distribution. Facilitate mining processing and manufacturing, and lower cost.

2. The raw material processing

Raw material processing including mineral separation, drying, burning, crushing and screening.

3. Ingredients and mix practice (mixed)

Ingredients are the raw materials (large, medium and small three kinds of particles, raw material and clinker), additive (binder, mineralizer) and water to coordinate according to certain proportion.

4. Molding and drying

The purpose of molding is to make the refractory products with specification density, appearance size and strength. Molding methods can be divided into new moon and semi-dry forming. Metallurgical industry to use the most is the half dry molding in refractory products.