Converter is fireproof environment of material lining work, working layer, filling layer and permanent layer include in converter firebrick lining. Working layer is mixed with molten steel, broken bits directly contact of heat vital energy, keep getting of the respect such as physics, mechanical, chemistry erode; Fill layer interpose is mixed at working layer between permanent layer, use tar magnesia normally or dolomite makings pounds tar to hit and be become, its action is to reduce the to furnace casing extruding when expanding in firebrick lining, prevent damage permanent layer, and can demolish incomplete brick conveniently; Permanent layer is used at protecting furnace casing, can bake bricks magnesium, the build by laying bricks or stones such as tar union magnesian firebrick is become, do not tear open commonly when furnace repair change.
Turn kiln the working environment of layer of job of firebrick lining build by laying bricks or stones is as follows: 1) firebrick suffers the effect of high temperature thermal current. Its action results from liquid state metal and slag, react especially the high temperature action of the area, make firebrick exterior bate, fused. In last few years, because connect the fine outside casting, furnace and smelt the development of special steel, requirement high temperature blows steel or high temperature tapping, make firebrick high temperature fused quickly. (2) firebrick is sufferred machinery is destroyed and pound. Fluid of the steel inside furnace and slaggy and ceaseless shift, churn acuteness, erode ceaselessly firebrick; When loading molten iron of useless steel, add, firebrick will get very big impact; When cleared mouth attachment, still can produce the mechanical effect such as concussion. 3, the effect that still can have urgent cold urgent heat. Converter steel-making is periodic. Temperature of the lining after tapping of each heat heat is very high, in fluctuation inside the time interval of two furnace, firebrick surface temperature drops quickly, temperature of below fusion one furnace rises quickly again, such furnace villages experience the effect of urgent cold urgent heat repeatedly, especially the effect that upside lining suffers is the biggest. (4) chemistry is eroded. Its chemistry is eroded basically originate broken bits, gas and molten steel. In advocating a course, strong chemical reaction produces inside converter, will fireproof tile is soaked, make its melt is destroyed.
Build by laying bricks or stones builds converter firebrick plan. (1) is used simple and easy on long law as string of 1 dish of construction. Converter bottom design breathes freely 8 pieces brick, 4 converter use dead hearth, abide by after falling first, go up, first inside hind the build by laying bricks or stones outside builds kind. Permanent layer basically uses 2) converter lining magnesia brick, working layer uses build by laying bricks or stones of magnesian carbon brick to build. Because of the magnesian carbon brick that uses inside furnace bigger, and all press pack with norms model, is not to press furnace of ordinal build by laying bricks or stones, the ability after cause share firebrick needs to make be assembled beforehand outside furnace in construction site enters furnace, press strictly when build by laying bricks or stones is built pack with norms model. (3) whole lining uses block of dry wet union (wet build by laying bricks or stones basically stands by tapping mouth) . On the exterior join of hearth, can undertake breathing freely after lining is finished the exterior join of component. (4) because build by laying bricks or stones builds converter lining firebrick after finishing be about to put into production, construction must plan as a whole elaborate organization, scientificly, strengthen cooperate, ensure converter build by laying bricks or stones is built quality, safe, quick. Generally speaking, operating a condition cannot be changed at will, it is the skill decision of course of the product that differs by production, engineering technology and operation personnel. But another when assure service life of liner of blast furnace firebrick important step is to safeguard.
Lining protects furnace to be able to make the land of service life twice of firebrick increases. So, of lining it is very important to maintain. The measure that converter repairs maintenance (1) is right around bedding face, use hot do as one pleases to repair makings is fixed repair. The spray that is used at the place such as trunnion fills. Change of this law lining is bigger, if timely gush fills,reach maintenance, can make lining life amounts to above 8000 times, if maintenance is undeserved, service life can amount to above 1000 times. (2) splashs broken bits to protect furnace. This law is joined in furnace a few burn magnesian ball or dolomite material gently, make the melting point of broken bits and viscosity rise, will contain through high-pressured nitrogen burn gently the broken bits of stone splashs magnesian He Baiyun to go up in lining, decrease be opposite when smelt the next time of lining erode. Generally speaking, every furnace should splash broken bits, can maintain the firebrick of lining so, make lining life achieves 20000 furnace above. Although this method has taller service life, but it needs much nitrogen, wasted many magnesian He Baiyun the resource such as stone, also take away much quantity of heat at the same time, and every furnace splashs broken bits, can affect steel-making efficiency. The advantage that splashs broken bits to protect furnace so has how old, need to be evaluated integratedly.
What element can affect the liner life of converter firebrick? Before developing magnesian charcoal brick, the liner of converter firebrick basically is the magnesia brick that is united in wedlock with tar pitch and magnesian dolomite brick, it is 200~300 small converter at first. Since magnesian charcoal brick applies successfully at converter lining, the application of magnesian charcoal brick in converter increasingly grow in quantity, at present converter is versed in line basically is build by laying bricks or stones of magnesian charcoal brick is built. Permanent line uses magnesia brick, juncture makings uses magnesium to pound dozen of makings character. The service life of transducer also work up does not splash broken bits furnace thousands of times to now, and through splashing broken bits, life can be amounted to by tens of thousands, the lining of firebrick turns into permanent. Normally, temperature of small converter tapping is high, smelt condition is poor, the quality that uses fireproof data is inferior also, its service life is corresponding also and consequently inferior.
Have to influencing factor of the life in converter firebrick lining: (Every increase the ferric oxide in broken bits of 1) slag composition 1% can decrease 1820 times with life; Content of the MgO in slag is higher, of lining erode smaller; The alkalinity in broken bits is bigger, of lining erode smaller. (2) tapping temperature is higher, life is briefer. Average temperature exceeds 1600 ℃ , every increase 50 ℃ service life halve. (3) fusion time is longer, namely fusion time is longer, become the service life that corrodes quickly and fusion time inverse ratio. (4) intermittence is operated. When smelting furnace stops, temperature drops, the temperature when opening furnace to use rises quickly, this meeting causes intense thermal shock, often produce thermal stress, cause corrode quickly, crackle flakes even, make lining life is reduced greatly thereby. (When 5) is imposing molten iron and furnace burden, of furnace retroflexion and be bumped or erode, what cause lining is intermittent attaint, answer to be repaired in time, otherwise, its service life will be reduced greatly.
Domestic converter agrees basically with firebrick and Japan. The magnesian charcoal brick of 18% chooses carbolic content commonly more, differ with Europe, the magnesian charcoal brick of 10%-15% of content of more choice carbon. If produce rhythm of negative loading, steel-making fast, should choose the magnesian charcoal brick with low carbon higher content, it is better to fight aggressivity because of its. Conversely, if steel-making rhythm is slow, intermittent time is longer, criterion appropriate chooses the charcoal brick with the higher volume that contain carbon.
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