Technical measures for smelting clean steel

Smelting clean steel should be based on the variety and application requirements. The operations of hot metal pretreatment-steelmaking-refining-continuous casting should be under strict control. The main technical countermeasures are as Neutral Ramming Mass

follows:
(1) Hot metal pretreatment. The sulfur content of molten iron in the molten iron desulfurization or triple desulfurization process should be less than 0.005% or even less than 0.002%.
(2) End-point control of converter compound blowing and steelmaking. Improve dephosphorization conditions, increase the final hit rate of the end point composition and temperature, reduce the dissolved oxygen content of the steel grade, Tundish Nozzle

and reduce the number of non-metallic inclusions in the steel.
(3) Slag blocking and tapping. The slag blocking is adopted for tapping, and the thickness of the slag layer in the ladle is controlled below 50mm. Can avoid phosphorus back and improve the yield of the alloy, reduce oxide inclusions.
(4) Ladle slag modification. In the tapping process, slag modifier is added to the steel stream. Reduce iron oxide and adjust ladle slag composition.
(5) Refining outside the furnace. According to the quality requirements of steel grades, one or more refining combinations are selected to complete the refining task of molten steel, to achieve dehydrogenation, extremely low carbonation, High Alumina Brick

extremely low sulfidation, denitrification, reduce inclusions and form control of inclusions, etc.
(6) Protection pouring. The use of protective pouring technology in the pouring process is particularly important for the production of clean steel. The ladle-tundish-crystallizer adopts long nozzle argon seal protection pouring, the

tundish adopts double-layer protective slag, and the crystallizer adopts protective slag. It has the function of adsorbing inclusions and reducing secondary oxidation.
(7) Tundish metallurgy. Organize reasonable molten steel flow and reasonable molten steel residence time in the tundish to promote the floating of inclusions.
(8) Crystallizer operation technology. Choose protective slag with proper performance; immersion nozzle centering and proper insertion depth; pulling speed and liquid level stability; applying crystallizer electromagnetic stirring

technology; controlling the flow of molten steel, which is beneficial to the upward discharge of gas and inclusions and improves the quality of the slab .
(9) Internal quality control of the slab. Use electromagnetic stirring and light pressure technology to reduce center looseness, center segregation and shrinkage. Increase the density of the slab.
(10) Use straight crystallizer arc continuous casting machine and vertical curved continuous casting machine to facilitate the floating of inclusions.

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Nozzle filling compound treatment method

In view of the impact of the nozzle filling compound on the quality of the molten steel in the tundish, part or most of the nozzle filling compound, which is very polluted by molten steel, is taken away manually, which greatly reduces the pollution to the molten steel and reduces the impact on the tundish. Corrosion of refractory materials. The specific operation method is as follows:
(1) Raise the ladle to a high position under the action of the hydraulic cylinder of the ladle turntable.
(2) Put on the ladle shroud, the lower port of the ladle shroud leaves the liquid surface and slag surface of the impact zone.Silica Ramming Mass
(3) Place the container for collecting nozzle filling compound under the ladle shroud port.
(4) Open the slide mechanism to the maximum position, that is, the upper and lower slide holes are aligned.High Alumina Brick
(5) Collect the nozzle filling compound.
(6) Approximately 1/2 to 2/3 of the nozzle filling compound will be collected, and the steel will be casted immediately.
(7) Lower the ladle and insert the ladle shroud into the molten steel in the impact zone.

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The impact of sintering temperature and holding time for refractory materials

refractory

Sintering temperature and holding time is an important external sintering refractory material. With the increase of temperature, the vapor pressure of the material increases, the diffusion coefficient increases, and the viscosity of the liquid phase decreases, thus facilitating the process of material transfer such as evaporation-aggregation, diffusion of ions and vacancies, particle rearrangement, viscous and plastic flow. So that sintering speed. Prolonging the sintering time can also promote the completion of sintering. However, in the latter stage of sintering, unreasonably prolonging the sintering time can sometimes aggravate the secondary recrystallization, but can not obtain a sufficiently dense product.
The firing temperature of refractory products should be controlled within the sintering temperature range, at this temperature should maintain the appropriate sintering time to complete the sintering, if continue to increase the temperature deformation of the body.

The impact of the atmosphere:
Atmosphere directly affects the firing effect and product quality. Burning atmosphere can be divided into general oxidizing atmosphere, neutral atmosphere and reducing atmosphere. Different materials for the green body should choose a different atmosphere to ensure the physical and chemical reactions in the body smoothly. At the end of sintering, the atmosphere (the type of gas in the pores) has an influence on the sintering when the pores are closed. Study of Al2O3 sintering found that when the gas solubility in the lattice is small and slow diffusion, the isolated pores is not easy to discharge from the body. For example, Al2O3 is sintered in argon and air. On the contrary, when the diffusion rate of gas in the lattice is fast enough, the atmosphere has no effect on the sintering end. If the atmosphere to control the defect structure has a certain role, you can speed up the proliferation and conducive to sintering.

It must be pointed out that the influence of firing atmosphere depends on the material composition, sintering conditions, the type and amount of additives, and other factors. Therefore, specific analysis should be conducted for different temperatures.

In the actual sintering process, the impact of the above factors are interrelated and mutually restrictive. The factors that play a major role under different conditions may be different.


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Cement rotary kiln refractory materials magnesium aluminum spinel brick

refractory materials

Magnesia-alumina spinel brick is high purity magnesia and pre-synthesized magnesium spinel as the main 6 material, the reasonable grading, high pressure molding, high temperature firing obtained products. Its characteristics are high, high strength, corrosion resistance, low coefficient of thermal expansion, thermal shock resistance, is the ideal transition from cement transition zone refractory materials for sale.
Magnesia-alumina spinel production of ingredients in the amount of magnesium aluminate spinel is not more good female, with the increase in the amount of spinel thermal shock resistance becomes better, but due to mismatch expansion will make g degrees (especially anti-fracture Strength) to Alz05 as the standard, the product A120: should not be large; 15% -20%, preferably 10% -18%, which is consistent with the experimental data of magnesia aluminum brick.
Magnesium aluminum tip stone brick main impurity is so z, should not exceed 1.5%.
Over the past twenty years, people have been seeking to replace magnesia-chrome bricks in addition to six valence-polluting technology, first of all, looking to the periclase spinel brick. The initial report was optimistic but gradually came the different message from the cement plant: "The kiln skin is not found." The eutectic temperature of the original spinel brick 4 cement is close to (slightly lower) the firing temperature of the cement. This is fatal, so spinel brick kiln lining in our cement kiln back to 15 ~ 20m to reach the transition zone, occupy the original high-alumina brick or ordinary magnesia-chrome brick position.
The academic community agreed that re20J affect the product's resistance to atmospheric changes, spinel brick in the transition zone is better than magnesia-chrome brick, one of the explanations is k205 content Below the M-K line, however, the addition of 4% re20J to spinel bricks improves the brittleness of bricks. When the expansion rate of only 113%, flexural strength 12MPa, will be. 05P kiln 38-40m area use 8 months wear 30mm, and commonly used spinel brick wear amount is 80 "120mm, and said that this high-speed rail bricks for burning belt can hang the kiln skin.
Spinel thermal shock resistance, anti-B 'alkali corrosion, acid gas erosion resistance, anti-atmospheric ability to change are better than ordinary magnesia chrome brick, but on the cement rotary kiln transition belt and discharge belt with refractory brick suppliers, Should also have a small thermal conductivity, good wear resistance, anti-shear fracture capacity, which determines the availability of spinel brick.
Wear resistance is poor, in the 2500t kiln can run stably for more than 8 months Feng Mao Wei angle.
China periclase spinel brick ingredients, the use of sintered high purity magnesia, mid-range magnesia and synthetic spinel sand (5i020 6% -20%), thermal shock resistance indicators are generally more than 10 times, the best of 2D Times or more. However, the high temperature flexural strength (1400Y, o.5h), roughly 2-3MPa, most products less than 3MPa, which is spinel brick to be improved technology. There are no national standards for the sharp stone blocks used in cement kilns, and all the manufacturing enterprises use each other for reference to form the spinel brick used in China's cement rotary kiln.
Spinel brick has the advantage of good thermal shock resistance, the use of clinker reaction during the spinel can form a thin layer of calcium aluminate protective layer, so that the liquid is not easy to penetrate, anti-spalling performance ratio Direct combination of magnesium chrome brick good. In the cement rotary kiln cooling zone and transition zone service life than the direct combination of magnesia-chrome brick to double. But slightly less resistant to erosion in the direct combination of magnesia-chrome brick. At the same time, spinel brick easy hydration, thermal conductivity larger kiln cylinder temperature than the use of direct combination of magnesia-chrome brick high.

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Coke oven repair with refractory materials

refractory materials

Coke oven repair with refractory materials
Coke oven refractory masonry minor repair is the preventive maintenance of coke oven masonry and routine repair. The project is small, generally do not stop production conditions, by the workshop repair personnel repair masonry defects. Ovens for minor repairs in coke ovens include: repair of gaps, cracks and holes, compacting of gaps between masonry and equipment, reworking of loose iron pieces embedded in masonry, replacement of adjustment equipment, opening of blocked ramps and burners Brick, replace the stove at the bottom with refractory brick, repair coke oven door refractory lining brick. Primary repair of coke oven masonry wet repair, semi-dry repair and dry repair three types.
Repair parts by the repair items are:
① roof area, including the top surface of the furnace roof sealing and renovation, flue cleaning, ramp opening, burner brick and conditioning brick replacement, stopper brick gunning and riser refractory lining material brick replacement.
③ Taiwan, including stoves, furnace walls and walls of the front wall to resist various types of damage to the repair and spraying, the furnace at the end of the refractory brick suppliers floor and door repair and replacement of furnace linings, furnace shoulder seam repair and so on. )
③ regenerator area includes both sides of the flue corridor and basement. Repair projects have refractory brick gas pipeline and dredging, sealing walls, gas pipe fittings and exchange switch and the furnace at the junction of the seal, a small amount of replacement and replacement of lattice bricks, regenerator wall furnace renovation of the furnace head and so on.
1. Wet repair wet method of making up mainly by gunning and wiping, these methods are used tools and operations are relatively simple, and the use of a wider range, regardless of hot, cold, or carbonization chamber walls, fire fighters Internal, regenerative room, ramp and furnace roof can be used in all parts. The main disadvantage of wet-fill furnaces is that while repairing old defects, they can cause new damage to the masonry.
(1) Spray gun Put the prepared mud into the shotcrete machine, use the pressure of the compressed air to press the mud out of the shotcrete machine and spray it on the damaged wall to repair the damaged parts. Spray a wide range of applications, regardless of the size of the cracks, peeling, Ma face, depression, etc., can be sprayed, can complement the red hot wall, but also make up for the lower temperature of the roof and regenerator area. The advantages are: simple operation, high speed and high efficiency, wide range of applications, can make the formation of scattered slurry sprayed on the masonry, the general requirements of the thickness of each layer of pulp is not more than 7mm, after the first layer of dry Second floor. The disadvantages of this method are as follows: the water content of mud is as high as 40%. When the mud touches the wall, the pressure of water vapor will affect the bonding between the mud and the wall due to the violent evaporation of water. At the same time, the sudden cooling of red-hot wall due to the mud with large water content caused the cracking of silica brick masonry and directly affected the life of the coke oven. Therefore, this method is currently not used, only for use with wiping or wiping more difficult to use.
(2) wiping first with a shovel shovel furnace wall to eliminate defects in the site of deposition of carbon, and compressed air purge, and then to be rubbed spray a layer of 3 ~ 5mm thick mud, and then use a large shovel to wipe the mud Press the wall of the defect site, stay for a few seconds and then slide the trowel along the parallel direction of the wall, each time the wall of the mud should not be too thick, so as not to mud due to gravity and fall off, mud After adhering to the wall, use a spatula to wipe the wall with the wiping layer.
Mud fill with mud water content than the mud is much smaller, so the side effects of masonry is relatively small. Wipe up is not suitable for smaller cracks, but for large cracks, holes, etc. make up quickly. Therefore, wiping is the current wet method of making up the main means. Wiping operation technology is more difficult to grasp, wiping well, hanging time can be long, therefore, need to repair hot in practice constantly sum up experience and find good methods of operation, in order to prolong a repair linked to the time.
2. Wet method of making up the mud
There are two main types of wet-fill muds; one is a siliceous or clay-based mud with water glass as the binder; the other is a clay mud with phosphate or phosphate as the binder. The former was widely used by various coking plants until the 1960s. Each time a subsidy was applied, the time was relatively short, usually two and a half months to one month or so. The latter started in the early 1960s. Due to its long hanging material (about the former 8 to 10 times), it is quickly adopted, instead of water glass mortar.
(1) Silicate Mortar Silicone mortar containing water-based glass absorbs CO2 and precipitates SiO2 gel at room temperature and high temperature. It not only adheres the mud material to the wall to be filled, but also has Higher intensity. In addition, Na2O (or K2O) in water glass can reduce the melting temperature of the clay to make it appear in advance of the liquid phase at high temperatures, and also promote the adhesion of the clay to the furnace wall. The bonding between the water glass gypsum and the wall is a physical combination. As the water in the gypsum is more watery, the water shrinks greatly after it evaporates, and the bond with the wall is not strong, so the hanging time is short.
Water glass preparation of clay fire clay, except for the mechanism of making up the same with the water glass of silicon fire mud, water glass at high temperatures, clay and clay brick can make kaolinite rapid formation of mullite crystals, thereby increasing the mud Strength and stability. However, clay prepared by using water glass must be used promptly. Otherwise, the SiO2 gel precipitated from water glass will lose its bonding ability with Al2O3. In the water glass mortar, by adding a certain amount of sodium carbonate (Na2CO3), the mud can appear early in the liquid phase at high temperatures, increasing the bond capacity of the mud.
Borax with a particle size of 0.2mm and talcum powder were mixed at a mass ratio of 3:10 and then mixed with a fine clay clinker powder in a mass ratio of 1: 6, and then prepared with a water glass solution having a density of 1.11 The required consistency. It will be better to use this clay to fill the furnace wall. ?
(2) phosphate cement phosphate (H3PO4) and refractories in aluminum, silicon and other oxides chemical reaction, can generate phosphate cementitious materials. The cementitious material has the advantages of plasticity, low temperature curing, high temperature sintering, high refractoriness, good thermal stability and strong adhesive force. Therefore, it is widely used in the hot repair of industrial furnaces.
In the coke oven repair mortar material, phosphoric acid as a binder clay material, with the most solid combination of silica brick masonry. Because of the action of phosphoric acid and Al2O3 in clay fire clay, a good cementitious material of aluminum phosphate cement is formed, which belongs to a fire-hardening binder that hardens when heated. Al2O3 (about 40%) in clay fire clay does not react with phosphoric acid at room temperature (has a slow action with Al2O3? 2H2O in the clay raw material) and dehydrates at about 200 DEG C to produce aluminum dihydrogen phosphate Al (H2PO4 ) 3 and aluminum phosphate (AlPO4) at 250-280 ° C to form an amorphous substance, which becomes H2 (AlP3O10) at 300-400 ° C and dehydrates to aluminum metaphosphate [Al (PO3) 3] at 500 ° C n, aluminum tetraphosphate [Al (PO3) 3] 4 is formed at 800 ° C, phosphorus pentoxide is partially decomposed and precipitated into cristobalite (AlPO4) at 1000-1200 ° C, while the major part Still tetra-aluminum trimetaphosphate [Al (PO3)
3〕 4, at 1300 ~ 1500 ℃ under the conditions of the reaction is relatively strong, long-term high temperature, AlPO4 will become pure corundum (Al2O3). The aluminum phosphate monobasic and the aluminum metaphosphate produced in the reaction of phosphoric acid and Al2O3 are good gelling materials. They are well integrated with the silica brick wall and gradually sintered to harden, and finally change the square quartz-shaped aluminum phosphate, not only high melting point, but also with a similar wall of silica brick crystal transition. When the temperature changes, it is relatively close to the expansion (or shrinkage) of the silica brick, which reduces the internal stress between the phosphoric acid mud layer and the silica brick wall, so that the repair layer can extend the hanging time.
Since phosphoric acid can work with impurities (MgO, CaO, Fe2O3 and other basic oxides) in clay fire clay at room temperature to form compounds such as magnesium phosphate, calcium phosphate and iron phosphate, the clay material has certain properties at room temperature Sticky. However, when the content of magnesium phosphate in the mud exceeds 1.5%, the mud will lose its plasticity at normal temperature, which is not conducive to the construction work of spraying and wiping. Therefore, it is usually required that the clay in the clay should be less than 0.5% MgO, CaO should be less than 1%, Fe2O3 the smaller the better. SiO 2 (about 50%) in clay fire clay and phosphoric acid at above 260 ° C will form SiO 2 [SiO (PO2) 2). Although SiO 2 and SiO 2 also belong to cementitious material , But they do not have the same crystalline conversion properties as silica bricks, so the bonding to silica bricks is far less than that of aluminum phosphate cementitious materials. Therefore, the current wet repair silica brick coke oven masonry using phosphate - clay mud instead of phosphate - siliceous mud.
Preparation of phosphoric acid-clay clay material: clay fire clay is prepared from clay clinker and raw materials. Clinker does not work with phosphoric acid at room temperature, so the low viscosity is not good for the spray and wipe, but its residual shrinkage is small, strength is good; raw material residual shrinkage, but the porosity is low, but also can improve the mud The adhesion, which is conducive to construction operations.
Clay sprinkler, generally 20% of the raw materials and 80% of the clinker with, and is the use of fine-grained mud; wiping mud with the ratio and size of the plant varies, Anshan Chemical The plant is made with 50% gunning material and 50% particle size less than 3mm clinker; while WISCO coking plant is made of 80% clay clinker with particle size less than 3mm and 20% clay raw material. Spray water content is generally 30% to 40%, while wiping material is about 17%.
Phosphoric acid in the amount of clay in the mud is: each 100kg spray material added to the relative density of 1.25 to 1.3 orthophosphoric acid solution (ie orthophosphoric acid and water diluted) 37 ~ 42kg; each 100kg wadding added relative density of 1.3 ~ 1.4 of orthophosphoric acid solution 26kg.
In the preparation of mud, in order to make full use of phosphoric acid and mud, and discharge the gas generated, the mud stir should be trapped after a day to use. But the test shows that the bonding strength of mud and silica brick decreased significantly with the storage time of the mud, so the mud should not be stored for too long after the modulation so as to prevent the mud from losing its chemical activity.
(3) Plastic Plastic Plastic is often used in the form of wiping and ramming for the repair of various industrial furnaces. Because it still needs to be mixed with liquid gelling agent before use, it still belongs to the type of wet wiping. Plastic materials can be divided into clay, aluminum, corundum, silicon, chromium, zirconium, silicon carbide, etc., of which clay and high aluminum used more generally. Plastic construction facilitation, repair part of the overall good, less gap, wear resistance, thermal stability, slag resistance, impact resistance are better. Its low thermal conductivity, but thermal storage ability.


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Molten steel temperature and carbon corrosion of aluminum-magnesium spinel refractories

refractory materials

With the progress of metallurgical technology, the performance of refractories material also put forward higher requirements. Because aluminum-magnesium spinel refractory material has the advantages of high melting point, low thermal expansion coefficient, thermal shock resistance and slag resistance, it is widely used in electric furnace, refined ladle and skateboard and other major parts. In high temperature conditions, the refractory materials for sale reacts not only with slag and reacts with molten steel, but also has an important effect on the refractory process.

Production practice shows that the molten steel temperature and its carbon mass fraction are the main factors that affect the reaction between refractory and molten steel. Therefore, it is very important to study the effect of molten steel temperature and its mass fraction on the erosion of aluminum-magnesium spinel refractory.

In this paper, Mg-Al spinel refractory brick suppliers were prepared by fused magnesia and fused corundum as raw materials. The effects of molten steel temperature and carbon mass fraction on the erosion of refractory materials were studied by thermodynamic calculation and thermal experiment. The chemical analysis of carbon in molten steel before and after the experiment was carried out, and the microstructure of the refractory suppliers was observed by scanning electron microscope.

(1) Thermodynamics analysis shows that Mg (g) and A1 produced by the reaction of magnesium oxide and aluminum oxide components with carbon in the refractory material with the increase of temperature. o (g) of the equilibrium sub-pressure increases.

(2) The experimental study shows that the erosion index of refractory increases with the temperature of molten steel, especially when the temperature is higher than 1630 ℃, the erosion index of refractory is affected by temperature. The corrosion index of refractory material decreases with the increase of carbon in molten steel when the boron (C) 0.12% of molten steel decreases, thus alleviating the erosion degree of refractory material.

(3) The erosion mechanism of molten steel to spinel refractories can be summarized as follows: First, the carbon and refractory components of molten steel react chemically with eroded refractory materials: secondly. The penetration of molten steel into the refractory material and the analysis of the low melting point phase in the refractory particles reduce the binding force between the refractory particles and exacerbate the degree of damage to the refractory material.

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The requirements of refractory materials for shaft kilns

refractory brick

① high temperature heat loss: refractoriness of not less than 1580 ℃ inorganic non-metallic materials and products called refractory materials. In the kiln under high temperature, do not soften, insoluble; in normal or abnormal circumstances, can maintain a certain structural strength and bulk density stability. This kind of refractory masonry lining of the kiln in order to maintain the normal operation and production.
② anti-acid and alkali chemical erosion: the material in the kiln of the calcination process, to go through a series of complex physical and chemical reactions, different parts of the acid gas or alkaline slag will erode the kiln lining. Especially in the firing zone, the reaction material in the high temperature liquid phase, the chemical effect of refractory material is more intense. So the material can not participate in chemical reactions, does not appear sticky phenomenon.
③ anti-material movement wear: shaft kiln calcination process, the material from top to bottom, from low temperature to high temperature, to the low temperature kept moving. The lining of the inner wall of the kiln body is always subjected to the movement of the material, especially the clinker formed after calcination is stronger and the wear of the lining is more serious. Therefore, masonry in the kiln body of the refractory material must have a strong anti-wear ability.
④ specifications of the size: refractory masonry quality of the kiln calcination process has an important impact. Shaft kiln is not round, calcined easily lead to "partial fire" phenomenon; brick surface uneven, contact is not close, in the kiln bottom position is unstable, due to thermal shock phenomenon will occur loose lining, reduce service life and kiln heat loss Increase and so on. Therefore, the shape and shape of the refractory brick must be standardized and accurate, which is to ensure the quality of the most basic conditions of masonry.

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Other refractory materials for industrial furnaces

refractory materials

Other industrial furnaces include boilers, gas stoves, heating furnaces. Building materials industry, the use of refractories furnace up, such as calcined cement industrial furnace and glass melting furnace.
Calcined cement rotary kiln working temperature in the firing zone for the 1450 ~ 1500 ℃, masonry subjected to high temperature and alkali erosion, the production of frequent rotation caused by masonry vibration, while the wear and impact of sports load, masonry Laying layer to make the brick temperature fluctuations, so the use of cement masonry with high refractoriness, good alkali resistance, high compressive strength, good thermal stability of refractories. Generally in the firing zone with the use of magnesia bricks or magnesia-alumina bricks, the calcining belt uses good quality high alumina bricks or phosphates high alumina bricks, and other places use clay tiles.
Glass kiln masonry suffered 1600 ~ 1700 ℃ high temperature role, with the material and glass chemical erosion and mechanical action, as well as dust, air erosion and so on. So the refractory material must have the ideal anti-erosion performance, and should avoid the glass in the stones, stripes, bubbles and other defects. According to this requirement glass melting furnace generally use high-quality silica brick, fused zirconia corundum brick, fused α-β corundum brick, thermal storage room using magnesia or magnesia chrome brick. Refractory industrial kiln, according to the calcined raw materials and firing products, common shaft kiln, rotary kiln, inverted flame kiln and tunnel kiln and so on. Shaft kiln masonry is subjected to high temperature and abrasive wear. Therefore, the refractory used should have substantially the same chemical properties as the calcined raw material, the refractoriness suitable for the calcination temperature of the raw material, and the good high temperature volumetric stability, mechanical strength and slag resistance. For example, calcined limestone and clay clinker can be used in clay kiln lining, calcined magnesite and dolomite shaft kiln lining magnesium, calcined bauxite with high alumina brick or high alumina brick.
Rotary kiln masonry due to rotation leaving the masonry vibration, while the movement of the charge also wear and impact masonry, masonry in addition to meet the requirements of the production process, but also should have high strength and wear resistance.
The flame-resistant kiln is affected by the high temperature effect and the scouring effect of the combustion air flow and the abrupt change in the temperature of the kiln cooling. Therefore, the refractory used has high refractoriness and mechanical strength as well as good thermal stability and high temperature volumetric stability Wait. Masonry use of refractory materials and firing products should be consistent, such as firing high-alumina refractory bricks and magnesia brick masonry using high alumina brick, magnesia brick and silicon brick.
Tunnel kiln due to the high temperature of the firing zone, masonry quality requirements. Therefore, the masonry should be used refractory, fire resistance, mechanical strength and load softening temperature are high, high temperature stability and good dimensional dimensions of the refractory material. At the same time the performance of masonry and firing performance should be adapted.

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Advantages and disadvantages of carbon blast furnace refractory material

blast furnace refractory material

The main carbon refractory material used for blast furnace are carbon brick, graphite carbon brick, graphite silicon carbide ladle brick, self-bonding or nitrogen-bonded silicon carbide brick and ramming materials.

(1) Characteristics of carbon refractory materials for iron making

1) Carbon refractory is the ideal refractory for blast furnace refractory lining material, it has the following advantages:

① Carbon refractory  has high refractoriness, it will neither melts nor soften in blast furnace.

② Carbon refractory’s thermal expansion coefficient is small, it has a good volume stability in large temperature range.

③ Carbon-saturated molten iron will not erode carbon brick, in certain cooling condition, the corrosion of the slag to the Carbon lining is also small.

④ Carbon refractory has high thermal conductivity and electrical conductivity, using carbon refractory in the furnace bottom and hearth can make cooler play full performance, thereby extending the life of furnace lining material to prevent burning through.

⑤ Carbon refractory has excellent cutting performance, it can be made into shaped products in a very small size to meet the masonry requirements.

2) The biggest drawback of carbon refractories is that carbon and graphite burn in oxidizing atmosphere. When temperature reaches 700℃, carbon refractories begin react with carbon dioxide, and 500℃ it will react with water, and higher than 400℃ it will be oxidized. So for carbon brick’s exposed part, a protective layer should be built.


(2) Silicon carbide brick

Silicon carbide brick is a kind of inert material, it has good thermal conductivity, small expansion coefficient, high temperature strength, small creep deformation, and also silicon carbide brick has good anti-slag, anti-iron scouring and corrosion resistance, besides, silicon carbide’s oxidation resistance is better than carbon materials. The main problem is to find a combination of alkali-resistant metal corrosion. Also useful in nitride-bonded or self-bonded silicon carbide refractories. To extend the life of lower part of furnace, it is better to use silicon carbide brick.


(3) Aluminum carbon brick

Blast furnace aluminum carbon brick uses high quality bauxite and graphite as main raw material, being added a small amount of silicon carbide and additives, using resin as binder, and finally burnt through a compression-molding process. Aluminum carbon brick has the characteristics of high temperature resistance, good thermal conductivity, good alkali resistance, low porosity, small dimensional deviation and low price. It can be used in blast furnace heart, furnace waist, furnace body, iron mouth area, bottom of the furnace and other parts.

The characteristics of unshaped refractory are as follows.

Compared with shaped refractory, due to can celled the complex firing process, unshaped refractory suppliers production process is simpler, it is easy to use. Unshaped refractory has the advantage of plasticity, easy complex product molding, and conducive to mechanized construction, and low cost, and unshaped refractory’s using life is similar to that of refractory bricks. Its refractoriness and chemical stability is close to or can reach the level of similar refractory bricks. Besides, unshaped refractories can be prefabricated into large pieces.

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Advantages and disadvantages of carbon blast furnace refractory material
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New trends of China refractory materials

New trends of China refractory materials

Refractory industry, a serious excess capacity is more prominent in the current situation. Therefore, we must resolutely control the production, firmly grasp the domestic and abroad markets. China is a large consumer of refractory material, refractory brick suppliers consumption accounts is about 60% of the total global consumption, is still the leading market for refractories. Therefore, no matter how the economic situation changes, the domestic market is still a large market for refractory consumption. At the same time, refractory production need to expand the international market.

Chinese refractory products exported to more than 150 countries and regions. It is noteworthy that Vietnam, Indonesia, the demand of refractory brick china is increasing. In 2016, the export volume of alkaline refractory materials up to 877,600 tons. refractory company  Silicate Alumina refractory material up to 662,400 tons. In this regard, refractory production and export enterprises need to stabilize the existing export market, at the same time, tracking changes of the international market timely, and further expand the market space, increase exports.

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New trends of China refractory materials

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How to prevent ladle refractory material sticky slag

Our Ladle Refractories has Ladle magnesia carbon brick,Alumina-magnesite Carbon Brick for Ladle, Ladle Unshaped Refractory Material, Ladle Permanent Layer Castable.

With the following proper methods, we could prevents the ladle refractory material sticky slag from steel making.
It will guarantee the better quality of steel.
1. Increasing the hot turnover of ladle and decreasing the quantity and time of turnover of ladle.
2. Do better cleaning work of ladle bricks ladle, clean the ladle timely and fully, especially for the ladle month part.
3. Repair the damaged parts of the ladle lining timely, to prevent the molten steel and slag from entering into the lining.
4. Pour the slag out timely after work, shorten the time from pouring to turning over of the ladle.
5. Improve the performance of the pouring molten steel from the converter, prevent the converter slag into the ladle. And added the lime when do refining, to make sure the steel is fully melted.
6. Control the quantity of ladle, shorten the time of ladle keep for waiting, and do preheating before put the ladle into work.
7. On ladle refractories material, better the masonry quality, use the suitale size of fire bricks and improve the capacity of thermal shock resistance.
8. With suitable ladel covering agent, the use of it will keep the ladle insulated and with less ladle slag.
9. Choose the same grade of mortar to refractory bricks, such as with clay mortar for clay firebrick and magnesia mortar for magnesia firebricks.

Article source:
How to prevent ladle refractory material sticky slag

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