The characteristics and classification of magnesia refractories

 The melting point of MgO is as high as 2800℃, and the refractoriness of magnesia bricks is generally high, reaching above 2000℃. Therefore, magnesia bricks have good high temperature resistance, high temperature vacuum stability is good, and strong resistance to alkaline slag , but magnesia bricks have poor resistance to sulfate erosion, poor thermal shock stability, and are easy to hydrate. In addition to traditional magnesia bricks, magnesia refractories also include forsterite refractories and magnesia alumina spinel high-quality refractories, magnesia-chrome refractories, white jade refractories, etc.

Magnesium chromium refractory material. It is a refractory material made of magnesia and chromite, and with magnesia as the main component. According to the chemical composition, magnesia-chrome refractory products include chrome bricks and chrome-magnesia bricks. Magnesium-chromium refractory products have high refractoriness, high-temperature strength, good thermal shock stability, strong corrosion resistance to alkaline slag, adaptability to acidic slag, and good kiln-hanging properties. Magnesium-chromium refractory products are mainly used in RH ovens, AOD furnaces, non-ferrous metal smelting furnaces and glass kiln regenerators, cement rotary kilns, mixing furnaces, lime kilns and high-temperature kiln linings, etc.

However, due to the environmental impact of hexavalent chromium ion harm to the human body. Magnesium aluminum spinel refractory material. It is a refractory composed of magnesia and spinel with a magnesium oxide content (mass fraction) of not less than 20%. However, due to the large variation range of A12O3 and MgO content, we will use A12O3 and MgO as the main chemical composition of the refractory. It is called magnesia-aluminum spinel refractory. Magnesium-aluminum spinel refractories are mainly used in large cement rotary kilns, glass kiln regenerators, electric furnace tops, refining furnaces outside the furnace, ladle and other thermal equipment for enhanced operations.

Dolomite refractory material. The main component is white jade clinker. White jade clinker refers to calcining natural magnesium calcium salts or hydroxides to form a uniform and dense mixture of calcium oxide and magnesium oxide. According to the chemical mineral composition, it can be divided into the following two categories.

Article Source:The characteristics and classification of magnesia refractories
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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Refractory products for AOD refining furnace

 The AOD furnace is an argon-oxygen blown converter for two-step steelmaking. It is an atmospheric refining furnace. Its appearance is similar to that of a converter. It is mainly used for smelting stainless steel.

The working characteristics of AOD furnace are:

1.High working temperature. In order to reduce the carbon content in steel to a very low level, the refining temperature needs to be increased to over 1700 degrees Celsius.

2.The molten steel is stirred vigorously. The spraying of a large amount of high pressure caused the molten steel to agitate violently.

3.The alkalinity of the slag changes greatly.

4.Intermittent operation.

The working process of the AOD furnace is to first blow oxygen to decarburize, then add ferrosilicon or aluminum to reduce the chromium in the slag, and then add lime for desulfurization. During the whole smelting process, the slag changed from acidic to alkaline, and the atmosphere changed from silicon oxide to reducing atmosphere. Due to the above working characteristics, refractory materials for AOD furnaces are required to have high refractoriness and high temperature strength. Good thermal shock resistance and strong slag resistance. Especially for the tuyere and the area around the tuyere, it is more necessary to use refractory materials with good corrosion resistance and peeling resistance. The refractory materials commonly used in AOD furnaces are magnesia chrome bricks, magnesia carbon bricks, and magnesia dolomite bricks. In order to form a balanced furnace lining, the upper part of the tuyere is fused and then combined with magnesia chrome bricks, the other parts are directly combined with magnesia chrome bricks, or the tuyere part uses pre-reacted magnesia chrome bricks, and the rest are magnesia dolomite bricks. The top of the furnace can be made of high-aluminum refractory castables and refractory plastics, or can be built with magnesia bricks.

Article Source:The development and function of long nozzle
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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The development and function of long nozzle

 The invention of long nozzle started from the demand for the protection of molten steel pouring. Its use played a good role in preventing the secondary oxidation and slag entrapment of molten steel, and played an important role in the development of molten steel continuous casting. Tundish liquid steel pollution in different periods of continuous casting are almost related to the long nozzle, which has attracted the attention of more and more metallurgical workers.

In recent years, long nozzle has been continuously upgraded in terms of materials, structure and process operations. The new designed long nozzle structure realizes the immersion pouring, which effectively alleviates the serious entrapment and air suction during pouring. With the development of continuous casting technology, refractories are taking on more metallurgical tasks, and the metallurgical functions of the long nozzle are becoming more diversified, such as detection of slag under the ladle, formation of dispersed bubbles, and prevention of filling compound pollution. But the primary task of long nozzle is still protect the pouring of molten steel.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality refractory products are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

Article Source:The development and function of long nozzle
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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Lining method of EAF bottom ramming mass

 After feed in EAF bottom ramming mass, use a shovel or a nail rake to level it, and then use an aluminum alloy long ruler and a level to level it, taking the baseline released in advance as the standard, and then spread a canvas on the leveled ramming material, and the canvas will ramming the furnace bottom cover it all.

Put two vibrators on the canvas and keep a certain distance between the two vibrators. At the beginning, the two vibrators are best placed on the two ends of the furnace diameter inside the furnace shell. This will not only avoid mutual interference, but also enable the operator to reduce dust damage.

After the vibrator is activated, it starts to vibrate from the outer ring and ramming from the outside to the inside. The next circle should overlap the previous one by one third to prevent missed beating. Continuously vibrate from the inside of the brick wall until the center of the furnace is regarded as-times. After the ramming is completed, the ramming is repeated several times from the outside to the inside, and each layer of ramming material is simultaneously rammed multiple times with two vibrators.

After each layer of ramming is finished, remove the dust-proof canvas, and use a homemade nail rake to pull the surface of the ramming material in the same direction and comb into grooves to help increase the contact area of the upper and lower adjacent layers to form a seamless overall ramming stove bottom.

The density of the ramming material after compaction should reach 2.8g/cm2 or more. At this time, the vibrator jumps up and down, the amplitude is larger, and the vibration sound is louder than the previous few times. These phenomena indicate that the material layer is basically solid.

Knotting quality inspection method: use a 4mm diameter iron rod, such as φ 4mm welding rod, the insertion depth does not exceed 20mm.

Article Source:Lining method of EAF bottom ramming mass
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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The development of low creep high alumina brick

 Low creep high alumina brick is an acquainted product for refractory material and steel making workers. In 1985,in order to realize the nationalization of refractory material for Baosteel second-stage construction, metallurgy organization pay more attention to the research the low creep high alumina brick reaching the Japanese level.

Until now, many factories can produce the higher quality low creep alumina brick for the blast furnace and cowper stove. The burdening of the most of homebred low creep alumina brick is to add the family of sillimanite materials, whose process is complicated and cost is higher.

Early guidance Tangshan Iron and Steel author refractory plant for Bao steel to develop low creep high alumina brick, but with pure silica powder as a secondary mullitization provenance, products in 1550 ℃ 0.2 MPa 50 h creep rate index level over Japan. There was no disclosure of the technical know how to add quartz. In fact, this is a lesson to be learned from an article in the Russian data. A Ukrainian Institute refractory low creep high alumina brick submitted on paper entitled. High alumina refractories with high creep resistance at temperatures. At first glance, the title seems to be no novelty, but its high-performance products. The technology index of industrial scale produced by this share company :w(Al2O3)>73%, show porosity ≥18%,compression strength >100Pa, Heavy softening temperature (0.5MPa)> 1750 ℃, the creep rate (1600 ℃ 1.5MPa24h) <0.09%.Here note load softening temperature and pressure values creep rate tests.

Low creep high alumina brick is generally cannot afford such high stresses. The products used in the lower temperature hot stove brick dome, more than 9.5 years of continued operations. Speaker did not introduce technical points, did not explain the materials used, but no mention of the addition of quartz. But between the lines describe a little trace impurities in the raw material properties, the industry can determine its so-called "purity of 99% SiO2" is quartz, quartzite and general purity. In fact, the use of fused alumina, activated alumina, and a quartz-based raw materials to manufacture non-uniform state technical essentials multiphase quartz reaction product is so fully realized mullite bonded corundum microstructure to achieve excellent high temperature performance.

Article Source: The development of low creep high alumina brick
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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The main elements for controlling electric furnace steel-making

 The main elements for controlling electric furnace steel-making are the supply and quality of steel scrap. Adopting DRI which is also called sponge iron steel becomes the most efficient and economic processing measure. In 2000, Sponge iron production reach 43 million ton in the world, the main country are Venezuela, Mexico and India. For India, it tried to produce sponge iron steel in 1980 and could not reach 10 million ton in 1990, while it reached 54 million ton. The processing measure for smelting sponge iron steel is not complicated. It is to mix mineral flour and coke equality, balling, roast in the ring kiln and reduced iron to get sponge iron and impurities product.

The surface temperature of rotary kiln lining is 1000 degree centigrade or so and, it can bear mechanical stress, slagging, washout and heat shock function . In preheating zone, about 900 degree centigrade , it happened C+CO2---2CO reaction, the mine partly and slowly is reduced and then it happened Fe2O3+CO---2Fe0+CO2 reaction. The temperature of material, but in the zone of reduction, it happened Fe2O3+CO---2FeO+CO2, this reaction absorbs the heat , the reactant material temperature is lower than 100 degree centigrade, the refractory lining bear the sudden change for temperature of fuel burning and material cooling.

Article Source: BOF furnace classification and related refractories
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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BOF furnace classification and related refractories

 BOF is a vertical cylindrical furnace that does not require an external heating source and mainly uses liquid pig iron as raw material for steelmaking. According to the nature of refractory lining, it can be divided into acid BOF and alkaline BOF. According to the position where the gas is blown into the furnace, it is divided into bottom blowing, top blowing, side blowing and top and bottom combined blowing BOFs.

Because of the different components of molten iron and refractory resources in different countries in the world, the choice of furnace lining bricks is also emphasized. The United States mainly uses tar-combined magnesia bricks, periclase bricks, and tar impregnated and fired periclase bricks. Magnesia carbon bricks have also been used since the 1990s. France mainly uses dolomite bricks, magnesia dolomite bricks, dolomite carbon bricks, asphalt bonded magnesia bricks and magnesia carbon brick. The United Kingdom once used tar dolomite bricks and fired dolomite bricks. After 1989, a large number of MgO C bricks were used.

Russia mostly uses tar dolomite bricks, and a few factories also use tar magnesia bricks and periclase spinel bricks. Japan is the first country to move magnesia-carbon bricks from electric furnaces to BOFs, and its use effect is in a leading position in the world. The development of BOF lining in China has gone through the process of tar combined with dolomite bricks, tar combined with magnesia bricks, magnesia dolomite bricks, high calcium magnesia bricks, magnesia dolomite carbon bricks and magnesia carbon bricks. In summary, all countries in the world are gradually using magnesia carbon bricks to replace other bricks. Magnesia carbon brick has good thermal shock resistance, strong corrosion resistance, excellent stability at high temperatures, good thermal conductivity, good wear resistance and good spalling resistance, plus the improvement and progress of smelting technology and gunning technology Since the 1990s, the service life of furnace lining has been greatly improved, and the consumption of refractory materials per ton of steel generally does not exceed 2kg.

Article Source: BOF furnace classification and related refractories
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The application of cement kiln refractories

 We often use magnesite chrome brick, high alumina brick, clay bricks, silicon mullite brick, phosphate bonded high alumina brick, magnesia spinel brick, high alumina castable, low cement castable, calcium silicate board and ceramic fiber products in the cement rotary kiln.

Changxing factory is located on Xinmi city, Henan Province with abundant raw material resources. Reasonable price and best service providing for you. We also have professional kiln designers help you to do the refractory solution for you. You can discuss with our engineer face to face and visit factory to see the process of steel making.

Changxing refractory provides refractory products, calcium silicate products, castable & mortar, china refractory brick, ceramic fiber felt, ladle & tundish nozzle, ceramic fiber with high quality for you. Such as high alumina refractory bricks, magnesia carbon brick, clay refractory bricks and other refractory products.

Article Source: The application of cement kiln refractories
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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The use and composition of ladle purging plug

 In modern steel smelting technology, ladle purging plug is a very important functional element in the out-of-furnace refining technology. Inert gases such as argon are introduced into the molten steel through the ladle purging plug at the bottom of the ladle to provide power for the stirring of the molten steel to achieve uniform steel. Aim to make the alloy composition and uniform temperature are average in the liquid steel. According to the assembly mode, the purging plug can be divided into integrated purging plug and seperated purging plug. Both are composed of purging plug core and well block. Whether integrated purging plug or seperated purging plug, the function of the well block is to protect the brick core and prevent molten steel from corroding to any position of the brick core except the working surface. Usually the bricks will be damaged as follows: Erosion of molten steel, spalling, transversely broken, longitudinally cracked of well block.

Ladle purging plug is a very important functional element in the out-of-furnace refining technology. Inert gases such as argon are introduced into the molten steel through the ladle purging plug at the bottom of the ladle to provide power for the stirring of the molten steel to achieve uniform steel.

Article Source: The use and composition of ladle purging plug
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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