The thermal shock stability of silica brick is not tall, be poorer in fireproof material, but temperature of its loading bate and fireproof degree more adjacent, silica brick has good repellency to acidity slag, commonly used at vitreous kiln, Jiao Lu, hot-blast stove, used good word can be used 10 to 20 years of above.
The quality mark of silica brick SiO2 not under 93 ％ . To Al2O3, feO, the oxide such as Fe2O3 also has good repellency, but poor to the counteractive ability of alkalescent slag, easy by CaO, k2O, na2O wait for oxide action and destroy. The loading bate temperature of silica brick is as high as L640-1680 ℃ , use bulk for a long time below high temperature to compare stability.
The composition of silica brick one, chemical composition silica brick is You Chunshi mix with a few milk of lime after stone classics calcination is handpick and become. Partial aggregate is used after usable useless silica brick is broken. Advanced silica brick raw material should learn to handle through become privileged, learn composition with the generalization of purify impurity silica brick.
Brilliant photograph is formed see not hard, of silica brick see not hard: The photograph composition of silica brick basically is SiO2 crystallization and the silicate crystallization such as a few siliceous calcium the sort with crystal SiO2 is very much, have quartz, scale quartz and Fang Shiying photograph of brilliant of 3 kinds of brilliant silica brick is comprised (%) is siliceous the silicate such as calcium is crystal what SiO2 crystallizes is a lot of more phyletic, fang Shiying 2080, Fang Shiying 315, vitreous photograph 440. In photograph of silica brick brilliant, melting point is higher is SiO2 crystal, melting point is 1713deg; C. Silica brick is impossible to be comprised by 100% pure SiO2. Because the purity of raw material is achieved hard,this is not, cannot be united in wedlock because of SiO2 crystal however, have other part so. These crystal appearances that become minute of composition and the melting point of a few glass photographs are low, rise to combine the function of SiO2 crystal grain, tie thing so. The crystal of big grain SiO2 in the brick calls aggregate. The corrosion resistance that ties thing and high temperature resistant the gender is poorer than aggregate. But combinative other people can make aggregate union too less inattentive, want to choose correctly to tie thing so.
(1) chemistry is mineral. The quality mark of the SiO2 in silica brick should is more than 93% . The brilliant photograph in general silica brick is scale quadrate and in season, in season with a few remain in season, matrix is vitreous photograph.
(2) true density and bulk density. The true density of silica brick is one of important signs that judge crystal change extent. The true density of general silica brick is less than 2.388/cm3, the true density of high quality silica brick is 2.33-2.34g/cm3. Silica is 2.65g/cm3. Scale quartz changes rate taller, firing the true density of silica brick is smaller. Accordingly, the mineral composition of silica brick can be judged according to the true density of silica brick. The bulk density of silica brick and hole rate are concerned. The hole rate of general silica brick is 17%-25% , bulk density is 1.8-1.95g/cm3. Of silica brick shape pressure is higher, bulk density is bigger. The structural strength that increases bulk density to be able to raise silica brick, hot conductivity and be able to bear or endure broken bits sex.
(3) fireproof sex. The fireproof sex of silica brick is inferior, temperature is between 1670-1730 ℃ . The quality mark as a result of SiO2, brilliant, foreign matter sort and amount have change a bit, dan Bo is moved lesser. The quality mark of 2 oxidation silicon is higher, the quality fraction of foreign matter is smaller, fireproof sex is taller. Especially A12O3, k2O, the quality mark of Na2O is higher, the fireproof sex of silica brick is poorer. Altogether, silica brick is fireproof the gender is not tall, cannot satisfy the requirement of aggrandizement smelt.
(Temperature of 4) bear bate. The bear bate temperature of silica brick is higher, it is commonly between 1620-1670 ℃ , as fireproof as its sex is adjacent. Its are main the reason depends on making silica brick advocate brilliant photograph is the reticulate structure that forms by the scale quartz that has spearhead macle and matrix viscosity taller vitreous photograph be caused by. Silica brick heats below load action, from begin bate to be out of shape destroy, temperature interval is not big, once reach bate temperature, can destroy quickly, bring about load bate to be out of shape temperature range is narrow. Begin bate temperature to be close to its fireproof sex, this is a kind of special function of silica brick.
(5) bulk stability. Silica brick is heating in the process, expand besides general heat outside, still can produce brilliant change, companion has bulk to expand. The remain that if have in the brick,did not change is in season, the meeting below high temperature continues to become scale in season or square is in season, produce larger volume to expand. Common silica brick heats from normal temperature when 1450 ℃ , bulk expands rate for 1.5%-2.2% , and from 1450 ℃ refrigeration arrives when 250 ℃ , bulk is contractive, remain eventually quite expand rate for 0.1%-0.9% . The remain of high quality silica brick expands rate do not exceed 0.3%-0.4% .
(6) fights thermal shock function; The crystal inside silica brick changes change is acuteness and quickly because of temperature, bulk expands suddenly or contract, produce greater internal stress, make silica brick burst or flake. Silicon is so fireproof the heat-resisting shake performance of firebrick is poorer, water-cooling falls in 850 ℃ only 1-2 second. But it is when the use temperature of silica brick when 600 ℃ above is fluctuant, because crystal does not have rapid change, performance of its heat-resisting shake is better. (7) defends broken bits performance. Silica brick serves as a kind of acidity firebrick, to acidity, weak acidity slag is mixed the furnace gas that contains caustic gas has very strong corrosion resistance. It still is had fight certainly corrode action. When because become,Si02 and CaO or FeO coexist, after Si02 absorbs a certain quantity of Cao and FeO, the fluid photograph with two kinds of older viscosity produces below high temperature, form the hole of frit drop or infiltration firebrick not easily.
How to realize the long-term heat preservation of silica brick hot-blast stove? Basis of silica brick hot-blast stove stops the accident of furnace time and maintenance position and equipment, can use different heat preservation method. (1) blast furnace inside 6 days cease wind, hot-blast stove has a lot of to inspect an item, cease hot-blast stove is burned before wind, burn roof temperature to permission higher cost can. (2) blast furnace inside 10 days cease wind, hot-blast stove did not inspect an item, blast furnace rests hot-blast stove of the refrigeration before wind, drop waste gas temperature especially, during heat preservation roof temperature under furnace is burned when 700 ℃ , temperature of the waste gas inside 10 days does not exceed 400 ℃ . If be long (be more than 10 days) heat preservation, use roof temperature under 750 ℃ burn furnace to heat; If abandon air temperature prep above 350 ℃ , undertake sending wind refrigeration, sirocco discharges atmosphere through flowing backwards by sirocco manager in. Affect construction into blast furnace to prevent sirocco change, should flowing backwards cease one is built to block a wall inside the sirocco conduit between wind canal and blast furnace. Hot-blast stove carries Wen Jiang on the head to come when 750 ℃ , compulsive combustion furnace, ask when combustion furnace again for 0.5~1.0h, roof temperature amounts to 1100~1200 ℃ . Undertake sending wind refrigeration when 350 ℃ . Cold blast rate is controlled in 100~300m3/min, wind pressure is controlled in 5kPa, air cooling by allocate and transfer of other blast furnace or installation fanner. The regular job process of operating sequence and hot-blast stove is same, every hot-blast stove burns by turns send wind. Every class hot-blast stove of every silica brick changes about. Use heat preservation of this kind of method many days 100, the effect is first-rate.
Fireproof material occurrence craze, fall off, easy how to wear away to do? Want to solve a problem thoroughly, need to be dug from germ, the analysis gives real reason, flourish Cheng Naicai is engaged in be able to bear or endure service of timber production, research and development is old, can solve all sorts of difficulty problems of liner of furnace of high temperature kiln, welcome broad new old friend to seek advice reach technical communication.
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