Refractory bricks for high-temperature industrial kilns
1、 The development trend of coke ovens with refractory bricks for coke ovens is to expand the volume of the carbonization chamber, reduce the partition between the combustion chamber and the carbonization chamber, shorten coke time, and improve production capacity. The roof, combustion chamber, carbonization chamber, ramp area, and regenerative chamber of the coke oven mainly use silicon bricks, while the rest use clay bricks, and the furnace head part uses high alumina refractory bricks. To build a modern large-scale coke oven, in order to select high-strength, high-density, and low expansion silica bricks, strengthen the furnace structure, and improve the thermal conductivity of the furnace wall.
2、 Refractory bricks for blast furnace are becoming larger and larger. New technologies such as high pressure furnace top, high air temperature, summary of spray, microcomputer control and so on are selected to strengthen training. The application conditions of refractory materials are extremely strict. The throat and body of blast furnace are generally clay bricks or high alumina refractory bricks, and the waist and bosh are mullite bricks, corundum bricks, Australiachrome corundum bricks and so on. In the 1970s, special refractory materials such as silicon carbide bricks combined with silicon nitride were used. The furnace hearth is often constructed with carbon bricks, microporous and ultra microporous carbon bricks, ceramic refractory materials, and carbon brick composite materials.
3、 The selection of refractory bricks for hot air furnaces mainly depends on the hot air temperature. When the air temperature is below 900 ℃, the selection of clay bricks with an air temperature of 900~1000 ℃, and the selection of high alumina refractory bricks, mullite bricks, or silica wire bricks for high temperature areas with an air temperature exceeding 1100 ℃, the selection of low creep high alumina refractory bricks, mullite bricks, silica bricks, and violet stone bricks as bricks and lattice bricks, Many hot air stoves now use fire-resistant balls instead of checkered bricks
4、 Refractory materials for hot metal pre-treatment. Hot metal pre-treatment is an important measure for producing stainless steel and low phosphorus steel, and improving the power of the furnace. During the process of desilication, dephosphorization, and desulfurization of molten iron, due to the effect of the flux, the alkalinity of the slag shakes from 0.5 to above 3.0, causing serious corrosion to the container lining. The slag part of the molten iron pre-treatment container does not need to be constructed by burning bricks, and different levels of Al2O3-SiC-C bricks are selected below the slag line.
5、 The development direction of the converter with refractory bricks is large-scale, high-temperature, and top bottom blowing. Due to the different application conditions of various parts of the furnace body, the corrosion rate of the lining is very different. Therefore, different types and qualities of lining are selected for summary and construction. Magnesium carbon bricks and magnesium dolomite carbon bricks are mainly selected for vulnerable areas such as furnace mouth, hat, furnace body loading mud, slag line, trunnion, tapping hole, and furnace bottom tuyere. Other parts and vulnerable areas such as furnace bottom vents should first choose magnesium carbon bricks. Magnesium dolomite bricks and fired oil immersed magnesium dolomite bricks.
6、 The development direction of refractory brick electric furnaces for electric furnaces is high-power and ultra-high-power electric furnaces and DC electric arc furnaces. The former is characterized by a significant increase in input heat energy per unit time, a significant reduction in melting time, and increasingly strict requirements for refractory materials. The latter has the economic benefits of energy conservation and low consumption of graphite electrodes. The roof has been changed from silicon bricks to high alumina refractory bricks with an Al2O3 content of 75% and 85%. Magnesium bricks, magnesium chromium bricks, and magnesium carbon bricks are directly combined. As a weak link in the furnace wall's good line area and popular part, the first choice is to cast magnesium chromium bricks, directly combined or magnesium chromium bricks and magnesium carbon bricks. The residual part of the upper part of the molten pool embankment is mostly made of bricks that are the same or similar to the popular part of the furnace wall. The furnace bottom is made of well sintered magnesia or fused magnesia, and the bottom electrode is added to the DC electric arc furnace. The structure of the furnace bottom is messy, and the raw materials used are the same, but there are certain requirements for conductivity, and the service life is correspondingly low.
7、 The open hearth furnace uses refractory bricks to replace the oxygen converter, and China still retains some open hearth furnaces. After the free use of oxygen top blowing operation, the exercise intensity has been strengthened. The lining is quickly damaged, and the roof has been replaced with magnesium aluminum bricks, magnesium chromium bricks, and square magnesium aluminum chromium composite pointed stone bricks instead of silicon bricks. The working layer of the furnace bottom is a sintered layer of fused magnesia sand, and the slope of the embankment is made of magnesia bricks. The top of the sediment chamber is composed of high alumina refractory bricks or magnesium aluminum bricks, and the grid bricks at the bottom of the regenerative chamber are made of clay bricks. High alumina refractory bricks are used in the middle and upper parts, and magnesium olivine bricks are also used in the upper part.
8、 The selection of refractory bricks for refining outside the furnace is a key technique for producing clean steel, increasing the power of the initial refining furnace, and ensuring smooth continuous casting. Up to now, there are dozens of refining methods used in industrial production, but most of the refining operations such as degassing, removing impurities, adjusting composition, and adjusting temperature are completed in steel drums. The refractory interference materials used in the elite equipment are subjected to thermal vibration, impact and corrosion of steel and slag in environments with significant changes in temperature, vacuum, slag alkalinity, and oxygen concentration in steel. Therefore, the quality requirements are extremely strict. According to the exercise technique and application site, commonly used are magnesium carbon bricks, magnesium dolomite carbon bricks, magnesium chromium bricks, fused magnesium chromium bricks, and cast magnesium chromium bricks. Steel fibers have also begun to use high alumina castables, low cement castables, and cementless low moisture castables.
9、 The refractory materials for steel casting equipment are mainly used in the continuous casting center tank, which is lined with silicon or magnesium insulation plates. The filters in the tank are mainly made of calcium oxide, zirconia, alumina or zirconia alumina refractory materials. The entire stopper rod is first made of aluminum carbon material, and the water slide is now made of aluminum carbon, mullite, corundum, chrome corundum, and aluminum carbon skateboards. For long nozzle, fused silica and aluminocarbon data are selected, as well as alumina zirconia composite data. For invasive nozzle, aluminocarbon and aluminocarbon composite data are selected. For sizing nozzle, zircon or zircon data are selected. For separation ring for horizontal continuous casting, single nitride is selected, and composite data such as silicon nitride boron nitride and Theron boron nitride are selected.
10、 The use of refractory bricks in steel drums has led to the continuous expansion of drum volume, improvement in steel temperature, and nitrogen spraying due to the demand for multiple furnaces of continuous casting and clean steel. Due to the influence of households, the conditions for using refractory materials are becoming increasingly strict. One of the developing trends is the selection of magnesium dolomite carbon bricks, aluminum magnesium for the slag line and other easily corrosive parts
