Refractory brick of cement kiln includes high alumina brick, mullite brick, corundum brick, silica brick, magnesia iron, magnesia alumina spinel brick and so on. Alkali resistant, wear-resistant, refractory products are more, refractory brick storage time is longer than amorphous, but should pay attention to dry and moisture-proof.
Rotary kiln outlet and cooling belt. Demand: The two refractory linings produce strong mechanical wear and chemical corrosion due to the joint action of high temperature clinker, secondary air and high temperature flame. Therefore, it requires good wear resistance, slag resistance and heat shock resistance.
Selection: The cooling belt generally uses a high aluminum brick (A1203 content 65%~75%), heat shock high aluminum brick, spinel brick, chrome magnesia brick, phosphate brick; High aluminum brick, refractory concrete (corundum aggregate), silicon carbide brick are commonly used at the discharge port.
Rotary kiln firing belt. Application requirements: The refractory lining of the rotary kiln sintering belt is mainly subjected to high temperature impact and chemical corrosion (alkali attack). Therefore, it is required to use fire-resistant and high-temperature refractory materials that are easy to hang kiln skin, and choose magnesium bricks and chrome-magnesium bricks.
Transition zone of rotary kiln (exothermic reaction zone). Requirements: The kiln skin will be suspended from time to time, the temperature changes frequently, the cylinder temperature is high, and the chemical erosion is serious. This requires the advantages of being able to withstand high temperature impact, high folding strength at high temperature, and small elastic modulus. High aluminum aluminum brick selection of corundum (A1203 content 50%~%), and directly with chrome magnesia brick, ordinary chrome magnesia brick, spinel brick mixed.
Preheater and calciner. Requirements: Selection of refractory high temperature insulation performance: the low temperature cyclone can directly cast castable (refractory concrete). Alkali resistant, wear-resistant clay bricks can be used in the following preheaters, calciners and connecting tubes, with the addition of thermal insulation composite layers. The top part is hung with firebrick, backed with slag wool, and can also be cast with castable. Castable is used on every bend. Semi-siliceous clay brick with dense structure can be used in the kiln tail ascending flue to prevent alkali corrosion.
Cement clinker cooling system. The refractory materials used in the grate cooling machine mainly include refractory brick, light cast brick, thermal insulation brick, heat insulation board and so on. Common chrome-magnesium bricks and high-purity aluminum bricks can be used in high temperature, cutting throat area, high temperature area and high temperature area. Clay bricks can be used in low to medium temperature areas.
How long can firebricks be stored? What are the storage precautions?
High temperature resistant brick can be stored for a long time, but attention should be paid to dry moisture-proof, magnesium brick moisture resistance is poor, moisture, deterioration, cracking loss. Magnesium bricks should be placed in a dry place when entering the factory and covered with tarpaulin. Storage capacity is not expired, do not burn magnesium bricks in the southern rainy season is better not more than 3 months, not more than half a year in the north, the fired magnesium bricks can be slightly longer. Prevent throwing and collision during handling.
The application range of various refractory bricks in cement kiln
Clay brick has good wear resistance, cold and heat resistance, small thermal conductivity, but high temperature resistance, chemical erosion resistance is poor, low compressive strength. Firebricks are cheap and are often used in various kilns. High alumina brick is generally used in rotary kiln firing belt. Compared with clay brick, its fire resistance and load softening temperature are higher, and its slag resistance is stronger.
Magnesia refractory brick includes magnesia brick, magnesia aluminum brick and chrome-magnesia brick. The chrome-magnesia brick used in cement kiln firing belt is an alkaline refractory material, containing 55% to 80% MgO and 8% to 20% Cr2O3. Strong slag resistance, corrosion resistance, high temperature resistance, high strength, but large thermal conductivity, poor cold and heat resistance, expensive, installation trouble. If used properly, the cycle can be doubled, with some factories using up to 400 to 500 days.
When storing magnesia firebrick, attention should be paid to moisture-proof, and the long storage period should not exceed half a year. When laying bricks, the longitudinal joint (bricks and bricks are 2~3mm, and the transverse joint (rings and rings) is 5~6mm, to prevent the brick from cracking when expanding at high temperature, because the expansion coefficient of magnesium bricks is about twice that of high aluminum bricks. When the kiln is lit, it gradually heats up.
Calcium phosphate brick is a new type of refractory material developed in recent years. It is made of phosphate combined with burnt bauxite aggregate, pressed by machine, and 42.5%~50% phosphoric acid solution is used as binder. Bricks made of aluminum phosphate are phosphate wear-resistant bricks. The above two kinds of bricks are non-sintered bricks, Al2O3 content is about 80%, with high temperature resistance, corrosion resistance, cold and heat resistance, wear resistance, high strength advantages, but high thermal conductivity. The phosphate brick is suitable for the firing belt, and the phosphate wear-resistant brick is suitable for the end of the cooling belt. Phosphate bricks replace high alumina bricks in cement and are widely used in cement industry.