the development of modern technology, greatly promotes the blast furnace technology progress in china, a greatly increased life expectancy. in addition to further optimize the furnace body structure parameters should be more reasonable, operation parameters, but also be attributed to the blast furnace lining refractory materials and construction technology progress. we are currently blast furnace lining refractory material application, preferably three more representative of the scheme. among them, a choice of high thermal conductive graphite carbon and semi graphitized carbon brick masonry hearth furnace burning: the microporous carbon brick with high thermal conductivity; and the use of ceramic cup technology; bosh, belly, lower stack using si3n4 combined with sic brick. the structure selection of materials with higher level, more expensive. scheme two with domestic charcoal block replacement scheme in a sintering brick, and domestic developed in conjunction with the si3n4 sic brick performance is close, and the price is much cheaper than the aluminum carbon brick instead of si3n4 combined with sic brick, in order to reduce the cost of the. scheme three the bottom structure of two identical, but in the bosh, belly, lower stack until the middle uses a lot of firing aluminum carbon brick instead of si3n4 combined with sic brick, further reducing the cost of blast furnace. the following on the blast furnace lining refractory material selection respectively to explain.
refractory hearth, furnace bottom choice
blast furnace, hearth is one of the important parts of the blast furnace, the length of life, life depends mainly on the two parts of the. therefore, the modern blast furnace in this part adopts mixed structure of carbon brick and ceramic cup. all the upper - lower bottom, rely on the surrounding cooling wall masonry ring carbon brick, the brick masonry hearth and bottom, in the central and medial masonry brick ceramic material ceramic target. using this structure, its purpose is to use the characteristics of carbon brick of good heat conduction performance, strengthen the furnace bottom cooling, the metal solidification isotherm (1500 ℃) to the upper bed, and the chemical reaction isotherm of 800 ℃ is pushed to the protective layer, thereby slowing the hearth erosion speed, prevent annular fault occurrence, prolong furnace life, in addition, the biggest weakness is the poor antioxidant capacity of carbon brick. although the blast furnace smelting is reductive atmosphere, but completely unmasked in contact with the furnace gas carbon brick, still very easy to oxidation. therefore, the neutral ceramic brick inside lined with a layer of high temperature properties especially good to protect carbon brick ovens during prophase and in furnace campaign is not oxidized ceramic cup technology, can effectively prevent the liquid slag and hot metal prematurely penetrative contact to carbon brick, indirectly, prolong the service life of blast furnace.
in the first scheme, we recommend that the bottom is a semi graphitized carbon brick and high thermal conductivity of graphite carbon brick, hearth sidewall for domestic microporous carbon brick, the brick to brick masonry is mo ceramic standard solution. in the two, third, we recommended not to domestic charcoal block instead of graphite carbon brick, semi graphitized carbon and microporous carbon brick, namely the bottom using semi carbonization of graphite not charcoal block, hearth sidewall using microporous not charcoal block, the block is not burning charcoal composite corundum brick masonry ceramic cup scheme. mo to brick and composite brown corundum brick has a strong ability to withstand high iron slag erosion, but also has a strong ability to scour. the hair, recommend this two kinds of materials for ceramic cup material scheme. scheme selection of firing brick, scheme two or three choose not charcoal block instead of firing brick, is based on the non burning model integrated bottom block used in anshan iron and steel, tisco, etc. after tiantie blast furnaces, has obtained the certain effect, but the price is relatively cheap.
two, the blast furnace tuyere region condition is one of the worst areas, in this region, scour, erosion, thermal shock three failure exist at the same time, especially to scour and erosion, destruction of this region caused by the huge brick; at the same time, the region is more holes, coupled with the refractory lining of tuyere area should to protect the lower carbon brick and corundum brick, but also effectively support the upper lining. therefore, the rationality of the structure design is very important. so, in our three scheme of corundum mullite composite bricks as the preferred scheme. corundum mo to anti brick compressive strength, flexural strength, anti erosion, anti erosion ability, but also has better seismic capacity. using centrifugal casting of corundum mullite composite bricks also body compact, masonry structure is tight, strong ability of anti erosion ability and resistance to mechanical wear and thermal shock.
slag, iron mouth region also should be combined brick structure is good. therefore, in the three scenario we recommend, air outlet, slag outlet are made of jade mullite composite brick structure.
three, strong erosion force
therefore, in this region using si3n4 combined with sic brick, high alumina brick brick point layout ai2o3 content greater than 70% is more reasonable. taking into account the alumina carbon brick especially burned into the research and application achievements microporous alumina carbon brick, we in the scheme two, third part of the selection of aluminum carbon brick instead of sic brick scheme.
four, in the middle of the main body, is the thermal shock damage, followed by mechanical erosion. in the refractory all, cast aluminum carbon brick especially firing seismic performance of microporous alumina carbon brick has excellent, but also has a certain ability to resist erosion. therefore, we choose the aluminum carbon brick in this area as a preferred solution, secondly, a grade high alumina bricks used on this site is also able to meet the requirements, and the price is cheap.
five, unshaped refractory material selection
unshaped refractory materials is an important part of blast furnace lining, plays a crucial role in the long campaign of blast furnace. in the blast furnace of unshaped refractory materials we start relatively early, and later through the digestion and absorption of advanced foreign technology, technology continues to improve, and development to a new level. recommended in the three scheme of supporting and refractories unshaped refractory materials, new results are developed by our institute, has been successfully used in large and medium-sized blast furnace in china, some products are also used for foreign engineering.
six, casthouse special refractories used in large and medium-sized blast furnace slag line, wire, iron ditch ditch and other parts, swing. the requirements of anti scour, erosion resistant, impervious, good oxidation resistance, long service life and convenient construction.
the iron, slag ditch, in order to prevent iron, slag hot metal and slag splashing, heat flow, smoke spread to reduce environmental pollution. slag ditch cover special refractory material combined with the domestic situation, the chemical combination of low cement ultra fine art production of steel fiber castables, requirements to meet or exceed the performance of foreign products of the same type of technology.
seven, hot air furnace refractory material selection
hot blast stove is the key equipment in the blast furnace system, has an important influence on a generation of hot blast stove of blast furnace campaign life, to improve the service life of hot air furnace, refractory bricks and refractory mud choose should has good fire resistance thermal shock resistance, masonry should also have the strength of the whole structure of good so, good tightness, good heat insulation. choose mu in refractory furnace, it is necessary to consider the life, but also consider the cost. the use of clay bricks and high alumina brick in hot blast stove in the lower part of the. in the upper stove in consideration of the high temperature air, using silica brick. refractory mortar and brick has the chemical composition of matching, high temperature performance slightly higher grade corresponding. in the furnace shell and the insulated lining choice between the coating as a protective layer, avoid harmful erosion on the furnace shell, the specific choice according to actual circumstances.
in the upper shaft, the damage is mainly due to decline in charge of lining erosion and chemical erosion. however, due to the new design of blast furnace is the inverted cooling wall technology, so the damage of lining cloth brings has greatly reduced. the chemical erosion mainly from potassium, sodium, alkali metal is reduced in the lower part of blast furnace, with the air rises to the upper shaft, the lining surface re solidification, aggregation, chemical reaction with the lining refractory, which cause serious damage to the lining, high-quality clay brick by vacuum impregnation phosphate processing, its resistance to alkali erosion greatly strengthen, at the same time the seismic resistance and strength has been improved, therefore, we choose the vacuum impregnation phosphorus clay brick in the upper shaft.