refractory

First of all, the most basic is the nature of silica brick belongs to acidic.The true density of silica brick is the smaller, the lime change is the more complete, in the oven,generated residual expansion is the smaller. In the silica brick, the true density of the quartz crystal is the smallest, the linear expansion rate is small, the thermal stability is better than that of quartz, the thermal conductivity is good, the fire resistance is high under load, the slag resistance and corrosion resistance is strong, and is the most stable volume form.  In the firing of good silica brick, the highest content of quartz scales, accounting for 50% to 80%. Fang Shiying accounted for second place, only 10% to 10%. Quartz and glass phase content in the 5% to 5%.When the working temperature is lower than 600 ~ 700 ℃, the silica brick volume change is large, the thermal shock resistance is poor, thermal stability is not good. If the long-term operating temperature of coke oven, masonry broken easily.Determine whether the thermal stability of silica brick is the true density of the key is that the true density of the size of the quartz is to determine one of the important signs.Silica brick is the ideal refractory product for coke ovens, and important parts of modern large and medium-sized coke ovens (eg, combustion chambers, ramps and regenerators) are constructed of silica bricks. In the oven process, the maximum expansion of silicon bricks occurs between 100 ~ 300 ℃, 300 ℃ before the expansion of the volume of the total expansion of about 70% to 70%.

Characteristics

Ceramic fiber board product quality of a material is solid, good toughness and strength, has excellent ability to resist wind erosion. Heating is not inflation, qualitative light, construction is convenient, can be arbitrary bending shear, is ideal energy-saving materials of kiln, pipe and other insulation equipment.

1. High crushing strength, long service life.

2. Low thermal capacity, low thermal conductivity.

3. Non- brittle material, good toughness.

4. Size precision, good flatness.

5. Easily cut installation, construction is convenient.

6. Excellent resistance to wind erosion performance.

7. Continuous production, uniform fiber distribution, stable performance.

Application scope

1. The back lining of cement building materials industry kiln keep warm.

2. Petrochemical, metallurgy, ceramics, glass industry kiln back lining keep warm.

3. Heat treatment furnace back lining keep warm.

Ceramic fiber, as a new refractory insulation material, has been one of the most popular insulation materials. It is mainly composed of SiO2 and Al2O3 and has high refractoriness over 1580℃.

The insulation mechanism of ceramic fiber can be explained in the following aspects:

(1) Poor heat transfer capability
Ceramic fiber is non-directional intertwined. Heat is transferred along the fiber, but the non-directional interleaving slows the heat transfer. Besides, when fiber is in contact with the hot face, it is seldom vertical contact. This makes it difficult for heat to transfer to fiber. When the contact points of the fiber reach 80%, heat transfer resistance gets higher. Since fiber itself is opaque, heat rays in the fiber cannot pass. And the area of fiber is small, so it receives less radiation and heat radiation is basically not transmitted in the fiber.

(2) Poor convective heat transfer capability
When fibers are intertwined together, a lot of gas chambers are formed. Those gas chambers are filled with still air. Air has poor heat transfer capability and prevents the invasion of hot air flow.

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A brick kiln is a type of tunnel kiln where wet bricks made of gangue and shale are fired into finished bricks. It is usually more than 140m long and 2.8m, 3.3m, 4.6m, 6.9m or 9.2m wide, according to the size of the kiln.

With the development of the brick and tile industry, tunnel kilns are widely used. Issues such as the ends, firing quality and energy consumption of the kiln are gradually emerging. The dome of the traditional dome tunnel kiln is built with T-shaped refractory bricks. Since refractory bricks have poor thermal shock resistance, there are always slitting and spalling problems. In addition, the horizontal thrust of the dome kiln is large, so the wall requires special reinforcement. This consumes a lot of materials and time.

Because the upper space is large and the temperature difference is great, this greatly affects the quality of products and increases coal consumption. In the recent decade, the tunnel kiln begins to be flat-topped. Initially, the flat top is built with refractory cement blocks and refractory concrete. But since these materials have poor thermal shock resistance, the service life is just 2 years, so it greatly increases the غير مجاز مي باشدt.

Ceramic fiber is made of alumina powder. The powder is melt at 2000℃ and then spun and blown into fiber. It has high purity, good thermal shock resistance and good acid and alkali resistance. Its service life can reach up to 10 years. It is easy and safe to install. It is only 1/20 of refractory bricks and has good energy saving performance.

Refractory bricks, also called shaped refractory materials, have high strength and wide applications and are easy to construct. They have been widely used in a variety of industrial furnaces.

(1) Common fire clay bricks are generally used in the refractory masonry of furnaces and kilns. in the linings, walls, bottoms and flues, they are used below 1250℃. When used in the combustion chamber, they can be used above 1400℃.

(2) High alumina bricks are generally used in the parts of furnaces exposed to high temperature, severe erosion and high load, burner bricks and some parts that have special requirements. They are allowed to be used at 1300-1650℃.

(3) Lightweight fireclay bricks can be used in the lining of furnaces to resist high temperature molten slags and corrosive gases. They can be used at 1150-1400℃.

(4) Lightweight alumina bricks can be used the low-temperature linings below 1350℃ and the parts that are not exposed to high temperature molten substances and erosion. They can be in direct contact with the flame.

(5) Common corundum brick can be used in the hot face of linings in heavy oil gasifiers, important parts of saline wastewater incinerators and radiant burners. It is generally used below 1600-1670℃.

(6) Silicon carbide bricks have high thermal conductivity, good thermal stability and high strength. They can resist the reductive atmosphere. They can be used in the lings that are required to have good wear resistance, good thermal stability, good thermal conductivity and reductive atmosphere resistance. they can be used below 1400-1600℃.

Article:http://refractorybrick.over-blog.com/

The raw material consumption of refractory materials refers to the amount of raw materials consumed when producing a ton of refractory materials.

The raw material consumption (Kg/ton) is equal to the ratio of the amount of raw materials consumed (kg) and the amount of qualified refractory materials (ton).

The amount of raw materials consumed is respectively calculated according to fired refractory products (according to the material), non-burnt refractory products (according to the material), special refractory (according to the material) and monolithic refractories (according to the material).

The raw materials consumed include raw material, clinker and waste bricks, but do not include mineralizing agent and binding agents (such as lime, pulp waste, iron phosphate, sodium silicate, aluminum sulfate, etc.).

Mullite is a general name of a series of minerals composed of aluminum silicate. It is rare. Mullite is the mineral generated by aluminum silicate at high temperature. Natural mullite crystals are needle-like and tufted. It can be used to produce refractory materials.

Mullite is the only binary compound under atmospheric pressure among Al2O3 -SiO2 binary system, expressed as 3Al2O3-2SiO2. Natural mullite is rare, so it is generally synthesized by the sintering method or fusing method. Its Mohs hardness is 6-7. Its refractoriness is 1800℃. At 1800℃, it is stable, while it is decomposed into corundum and liquid at 1810℃.

Mullite brick is a high quality refractory material. It has a uniform expansion, excellent thermal shock resistance, high softening point under load, small high temperature creep, high hardness and good chemical corrosion resistance. Currently, mullite bricks mainly include high purity fused mullite brick, common fused mullite brick, sintered mullite brick made of natural bauxite ore and light burned mullite brick.

High temperature mullite insulation brick is a new energy-saving refractory material. It has high temperature resistance, high strength, small thermal conductivity and good energy-saving effects. It is widely used in petroleum cracking furnaces, metallurgy hot stoves, ceramics roller kilns, tunnel kilns, porcelain drawer kilns, crucible furnaces and the lining of a variety of electric furnaces. It can contact with flame directly.

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Magnesia carbon brick is made of MgO (melting point 2800 ℃) and carbon material with a high melting point that is difficult to be infiltrated by slags by adding a variety of non-oxide additives. It is mainly used in the converter, AC arc furnace, DC arc furnace lining, ladle slag lines and other parts.

The factors for the production of MgO-C bricks include raw materials, binding agents and additives.

1) Magnesia sand

Magnesia sand should have high purity. Compared to sintered magnesia brick, fused magnesia brick has more complete crystal structure and stable reducing effect on carbon, so the production of magnesai brick turns to fused magnesia bricks. Given the binding state of carbon and infiltration of binding agents, fused magnesia can be mixed with sintered magnesia.

MgO-C brick made of magnesia sand with high MgO content, large periclase particles and a lime-silica ratio of greater than 2 has the best quality.

2) Graphite

Graphite is another raw material for MgO-C bricks. It has good basic refractory properties. It contains 85%-98% fixed carbon and 13%-2% ash nd has a relative density of 2.09-2.23 and a melting point of 3640K ( volatile).

There are three reasons for the oxidization of graphite during use:
a. Oxygen in the air
b. Oxides in the slag
c. Oxides in graphite itself

Oxide impurities can react with graphite and make the structure loose, permeability increased and strength reduced, which is the main reason for the damage of magnesia carbon brick. Therefore, graphite with high purity and large flake crystals is mainly used for the production of magnesia carbon brick.

3) Binding agent

Binding agent is important for MgO-C refractories and other carbon refractory products. Graphite and refractory oxides are not miscible. Thwy rely on binding agents to bond. At high temperature, the binding agent will be carbonized and form carbon bond with graphite. These binding agents are typically phenolic resins, modified bitumen, petroleum cracking by-products. Among them, phenolic resin has the best performance.

4) Additives

During the damaging process of MgO-C bricks, the oxidization of graphite is the main reason. The oxidation and carbon loss result in loose structure and weak strenth. In order to improve the oxidation resistance of MgO-C bricks, a certain amount of additives are added, including silica powder, alumina powder, FeSi alloy, CaSi alloy, SiC, Si3N4 and B4C. another function of additives is to build a bridge between refractory oxides and graphite and reinforce the binding between refractory oxides and graphite.

Fire clay brick accounts for an important position in the refractory industry. The most important feature of fire clay brick is that the raw materials can be obtainded locally.

Fire clay brick is cheap and durable. It can be used for fire protection, thermal insulation, sound insulation and moisture absorption. Therefore, it is widely used in industrial production. The scrap bricks can be reused as aggregate.

When purchasing fire clay bricks, some professional knowledge is needed and some principles should be followed.

1) Take your need into account, such as specifications and materials.

2) Select appropriate manufacturers. Shop around and capare the price before you buy. Also pay attention to the credibility of manufacturers, after sales service, product quality and service attitude.

3) After selecting a manufaturer, give a visit to the factory to understand the strength of manufacturers, scale, production qualification, production capacity and evaluation on the product from other customers.

4) Pay attention to the proper use of fire clay brick in the production and the implementation of safety measures so as to make full use of fire clay brick, reduce unnecessary losses, extend the service life ansd reduce the غير مجاز مي باشدt.

Magnesia brick is a basic refractory product with periclase as its main mineral phase. It contains not less than 91% MgO and not less than 3.0% CaO.

Magnesia brick is composed of 80-90% periclase and 8%-20% other mineral phase including magnesium ferrite (MgO·Fe2O3), forsterite (2MgO · SiO2) and Calcium and magnesium olive stone (CaO·MgO·SiO2).Silicate glass contains about 3-5% magnesium, calcium and iron. These silicates may contain tricalcium silicate (3CaO · SiO2), magnesium rhodonite (3CaO · MgO · 2SiO2), calcium and magnesium olivine and forsterite, dicalcium silicate (2CaO · SiO2).

Magnesia brick has good thermal conductivity, good thermal expansion, good corrosion resistance to alkali molten slags and bad corrosion resistance to acid molten slags. Due to the low-melting silicate cements surrounded periclase, the beginning point of the softening temperature under load is not too high, but the collapse temperature is close to the beginning point. Its refractoriness is over 2000℃, but it does not make sense in the actual use. Bad thermal shock stability is one of the main reasons for the destruction.

In the storage and transport, special attention should be paid to moisture-proof to avoid burst after affected with damp.