refractory performance is one of the factors that affect the service life of the blast furnace is very important. according to the working conditions to determine the index of blast furnace lining refractory performance, which has important significance to the development of blast furnace refractory material of new varieties and bf design and construction. the following important performance index of blast furnace refractories:
(1) thermal conductivity
thermal conductivity of blast furnace refractory material rate, especially on the hearth, furnace carbon brick, is a very important index. the blast furnace cooling wall by cooling the cooling equipment to be protected, and cooling equipment to give full play to the role of need refractory materials has high heat conduction heat transfer ability, therefore hope that the hearth, furnace carbon brick is higher in high temperature rate, to enhance the cooling effect, the erosion speed slow brick. as everyone knows, reduce the lining erosion caused by various reasons lining temperature will reduce. for example, the lining by slag, iron penetration and corrosion degree will decrease with the temperature; erosion of alkali metals and zinc on the lining mainly occurred in 800~1000 ℃, if the cooling temperature to 800 ℃, erosion of alkali metals and zinc on the lining will greatly ease. however, some parts of the lining of blast furnace is not requiring high thermal conductivity, such as ceramic cup brick requires good insulation properties, low thermal conductivity, the upper part of the shaft lining does not require high thermal conductivity.
(2) the corrosion resistance to molten iron
blast furnace with carbon brick masonry, hot metal corrosion is the main reason for the carbon bricks eroded. in the blast furnace overhaul often found, bottom carbon brick samples of w (fe) is very high, some even as high as 40%, and a network like distribution; hearth in the sample w (fe) can reach more than 10%, granular distribution dispersion. this shows that the erosion of hearth furnace molten iron, carbon brick is very serious. reduce the hot metal corrosion index of refractory materials, to prolong the life of blast furnace is very important.
(3) alkali resistance
sinter, coke and other raw material into the furnace of alkali metals and zinc is the important factor causing the lining erosion and destruction. there are many blast furnace hearth girth brick wall, bottom side, also related to the erosion and alkali metals and zinc. in a certain temperature of potassium vapor will penetrate into the inner lining, reacted with silicon and aluminum components, generation of potassium silicate, jia xiashi and other compounds. the reaction process is accompanied by a volume expansion, which will damage the lining, especially the stack to bosh commonly used silica alumina brick.
(4) slag resistance
in the blast furnace ore soft melting region, primary slag formation, its essential feature is the high content of feo, have very strong on the lining erosion. lower stack, belly, bosh and hearth area of the lining are affected by the slag erosion. if these parts of the brick for slag resistance is not good, will soon be erosion. previously, many of our country's bf with high aluminum brick or clay brick masonry, although of great thickness, but the general production of 2~3 years has been eroded away, the main reason is that these refractories slag corrosion resistance is very poor.
(5) micro porosity index
micro porosity index of blast furnace refractory material mainly refers to less than 1 micron pore volume and average pore diameter. molten iron carbon brick first base material carbonaceous particles around voids, cracks, infiltration of carbon brick, the brick split into pieces, the brick lose strength. the chemical erosion of alkali metal, zinc, co2 and water vapor oxidation erosion is gas first penetrate the lining, deposited in the appropriate temperature conditions and the chemical reaction with the brick lining, failure. that is to say, whether it is carbon or silicon aluminum brick, has the very big relations they erosion degree in the blast furnace and the microporous structure. therefore, the micro pore structure is an important index to characterize the corrosion resistance of blast furnace refractories.
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