The development of modern technology has greatly promoted the progress of blast furnace technology in our country, and the life of blast furnace generation has been greatly improved. This should be attributed not only to the reasonable structure parameters of blast furnace body and the further optimization of operating parameters, but also to the progress of furnace lining refractory materials and construction technology. According to the current domestic application of BF lining refractory, we have made three representative schemes. Among them, in the first scheme, high thermal conductivity graphite carbon and semi-graphitized fired carbon bricks are selected to build the bottom of the furnace: the furnace cylinder adopts micro-porous carbon bricks with high thermal conductivity; And adopt ceramic cup technology; si3N4 combined sic bricks are selected for the furnace belly, waist and lower body. The material grade selected for this structure is higher and the cost is more expensive. In the second plan, the burnt carbon brick in the first plan is replaced by a domestic charcoal block, and the performance of the domestically developed and si3N4 combined sic brick is close, and the price is much cheaper, and the aluminum carbon brick partially replaces the si3N4 combined sic brick, in order to reduce the cost. Scheme 3 adopts the same furnace bottom structure as scheme 2, but a large number of fired aluminum-carbon bricks are used to replace si3N4 combined sic bricks in the furnace belly, waist, lower body and middle, further reducing the cost of the blast furnace. The selection of furnace lining refractories is described below.

Selection of refractory materials for hearth and hearth bottom

Furnace bottom and furnace cylinder are important parts of blast furnace, and the length of furnace life mainly depends on the service life of these two parts. Therefore, the mixed structure of carbon brick and ceramic cup is adopted in this part of modern blast furnace. All the lower part of the furnace is made of carbon bricks, the upper part of the furnace is made of ring carbon bricks near the peripheral cooling wall, and the parts of the furnace cylinder are also made of carbon bricks. Ceramic marks of ceramic materials are laid on the bottom of the furnace and inside of the carbon bricks. Using this structure form, the purpose is to use the characteristics of carbon brick heat conduction, strengthen the cooling of the bottom of the furnace, the solidification isotherm of hot metal (1500 ° C) is pushed upward, and the chemical reaction isotherm of about 800 ° C is pushed to the protective layer, so as to slow down the erosion rate of the bottom of the furnace, prevent the occurrence of circular faults, and extend the service life of the bottom of the furnace. The big weakness is poor antioxidant capacity. Although the smelting property of the blast furnace is a reducing atmosphere, the carbon bricks exposed in contact with the furnace gas are still very easy to oxidize. Therefore, the ceramic cup technology, which is embedded with a layer of neutral ceramic material with high temperature and good physical and chemical properties to protect the carbon brick from oxidation during the oven and the early stage of the furnace service, can effectively prevent the liquid slag and hot metal from penetrating into the carbon brick prematurely, and indirectly extend the service life of the blast furnace.

In Plan 1, we recommend the ceramic target of semi-graphitized carbon brick with high thermal conductivity at the bottom of the furnace, domestic micro-porous carbon brick on the side wall of the furnace cylinder, and mullite brick on the inside of the entire carbon brick. In Plan 2 and 3, we recommend replacing the high thermal conductivity graphite carbon brick, semi-graphitized carbon brick and micro-porous carbon brick with domestic non-carbonized block, that is, the semi-graphitized non-carbonized block is selected for the bottom of the furnace, the micro-porous non-carbonized block is selected for the side wall of the furnace cylinder, and the inner side of the entire non-carbonized block is the composite brown corundum brick ceramic cup scheme. Mullite brick and composite brown corundum brick have a strong ability to resist slag iron erosion, but also have a strong scouring ability. The two materials are recommended as ceramic cup materials in the scheme. Scheme 1 uses burnt carbon brick, scheme 2 and 3 use non-burnt carbon block instead of burnt carbon brick, based on the use of the new integrated furnace bottom with non-burnt carbon block in Angang, TiSCO, Tiantie and other blast furnaces, has achieved a certain effect, and the price is relatively cheap.

Second, the tuyere area is one of the areas where the working conditions of the whole blast furnace are harsh. In this area, three kinds of damage such as erosion, erosion and thermal shock exist at the same time, especially erosion and erosion, which cause great damage to the brick lining in this area; At the same time, there are many holes in this area, and the refractory masonry in the tuyere area should not only effectively protect the lower carbon brick and corundum brick, but also effectively support the upper brick lining. Therefore, the rationality of structural design in this area is very important. Therefore, in our three schemes, corundum mullite composite bricks are used as... Plan. Corundum mullite brick has high compressive and flexural strength, strong anti-erosion and anti-erosion ability, and has certain anti-seismic ability. The corundum mullite composite brick made by centrifugal casting is dense and the masonry structure is tight, and it has strong ability of resisting erosion, mechanical erosion and thermal shock.

Slag, iron mouth area should also choose composite brick structure. Therefore, in the three schemes we recommend, the tuyere and slag mouth are all selected as the combined brick structure of jade mullite.

Third, the mechanical scouring force is strong

Therefore, it is reasonable to select si3N4 combined sic brick in this area, and arrange high-aluminum brick with AI2O3 content greater than 70% in the brick in a point shape. Considering the research and application results of aluminum-carbon brick, especially the sintered microporous aluminum-carbon brick, we adopt the scheme of partially choosing aluminum-carbon brick instead of sic brick in scheme 2 and 3.

Fourth, in the middle of the furnace body, the main damage is thermal shock, followed by mechanical erosion. Among all the refractory materials, aluminum carbon brick, especially the fired microporous aluminum carbon brick, has excellent seismic performance, but also has a certain anti-erosion ability. Therefore, we choose aluminum carbon bricks in this area as... Second, a high aluminum brick used in this part can also meet the requirements, and the price is cheap.

In the furnace body, the damage is mainly due to the mechanical erosion and chemical erosion of the lining caused by the drop of the charge. However, because most of the newly designed blast furnaces use the inverted cooling wall technology, the damage caused by the cloth to the lining has been greatly improved. Chemical erosion mainly comes from potassium, sodium, alkali metals are reduced in the lower part of the blast furnace, as the air flow rises to the furnace body, the brick lining surface is re-solidified, aggregate, and chemical reaction occurs with the lining refractory material, thus causing serious damage to the furnace lining, the first clay brick through vacuum impregnation phosphoric acid treatment, its alkali metal erosion resistance is greatly strengthened. At the same time, its shock resistance and strength have also been improved to some extent, so we choose vacuum impregnated phosphorus clay brick in the furnace body.

Fifth, the choice of amorphous refractory materials

Amorphous refractory is an important component of BF lining and plays a vital role in BF longevity. In the blast furnace with amorphous refractory research, we started relatively early, and later through the digestion and absorption of foreign technology, technology continues to improve, and developed to a new level. The amorphous refractories recommended in the three programs are new results developed by our institute, and have been successfully used in domestic large and medium-sized blast furnaces, some of which are also used in foreign projects.

6. Special refractory materials for iron field are used in large and medium-sized blast furnace iron lines, slag lines, iron trenches, swing trenches and other parts. It requires anti-erosion, anti-erosion, non-penetration, good oxidation resistance, long life and convenient construction. The iron and slag ditch is covered to prevent hot metal and dissolved slag from splashing, hot air flow, and dust from spreading out to reduce environmental pollution. The special refractory material for iron slag trench cover is a low cement steel fiber castable produced by chemical combination of ultrafine powder, which can meet or exceed the technical requirements of the same type of products abroad.

7. Selection of refractory materials for hot blast stove

Hot blast furnace is the key equipment in the whole blast furnace system, the life of hot blast furnace has an important impact on the first generation of blast furnace life, in order to improve the life of hot blast furnace, the selection of refractory brick and refractory mud should have good fire and hot and cold, masonry should also have good overall structural strength, so that it has good sealing and heat preservation. In the selection of refractory materials in hot blast stove, both life and cost should be considered. Clay brick and high aluminum brick are used in the middle and lower part of hot blast stove. In view of the high wind temperature, silicon bricks are used in the upper part of the hot blast stove. The selection of refractory mud has a matching chemical composition with brick, and the grade with slightly higher high temperature performance corresponds to it. Choose spraying paint as a protective layer between the furnace shell and the insulating furnace lining to avoid the erosion of the harmful ingredients in the furnace shell, the specific choice can be determined according to the actual situation. (The above article is reproduced in the network, if there is infringement, please contact)