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Introduction of refractory materials for electric arc furnace

2021-02-03 11:15:08
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Magnesia-zirconium bricks have high refractoriness of Liaoning magnesia-chrome bricks. The melting point of zirconia is 2715℃, and the temperature exceeds 1660℃ before being corroded by clinker. Another feature of zirconia particles is that microcracks are formed around the particles, which absorbs external Stress, under hot and cold conditions, has greater fracture strength. It has obvious advantages in the corrosion resistance of the clinker liquid phase, the influence of the redox atmosphere and the compressive strength. Early magnesia-zirconium bricks had the characteristic of higher thermal conductivity than spinel bricks, and this situation has been improved. Magnesia-zirconium bricks have excellent performance and are used in cement kilns with harsh working conditions. With further improvement of performance and maintaining excellent gas, the production cost is reduced, and it is convenient for popularization and application.


Directly bonded magnesia-chrome bricks have good high temperature resistance, SiO2 corrosion resistance and oxidation-reduction resistance. At the same time, it has high high temperature strength and resistance to mechanical stress, and good kiln skin hanging performance, which is widely used in the firing zone.


The chromium spinel in the magnesia chrome brick is difficult to be wetted by the cement component. It is generally believed that the Cr2O3 dispersed in the liquid phase can increase the viscosity of the liquid phase and inhibit the liquid phase from penetrating into the deep part of the brick. Therefore, it is in the burning zone of the cement rotary kiln In the high temperature area, most of them use magnesia chrome bricks. However, under high temperature, the cement clinker and the brick are in direct contact, so that when the brick is melted, the magnesium oxide reacts with the cement clinker to form CMS, which accelerates the damage of the brick.

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When magnesia-chrome bricks are used in cement kilns, under the action of alkali, trivalent chromium is converted into hexavalent chromium with extremely strong oxidizing ability. The content of chromium in the air exceeds 10mg/m3, and the chromium content of the aqueous solution exceeds 0.5mg/ At L time, it will cause extremely serious harm to the human body. Since the mid-1980s, industrialized countries have formulated a series of environmental protection, sanitation and other specifications, and the use of magnesia chrome bricks has been restricted to a certain extent.


First of all, let's understand what kind of furnace the electric arc furnace is. The industrial furnace that generates electric arc heating by metal electrode or non-metal electrode is called electric arc furnace. Electric arc furnaces can be divided into three-phase electric arc furnaces, consumable electric arc furnaces, single-phase electric arc furnaces and resistance electric arc furnaces according to the arc form. The furnace body of the electric arc steelmaking furnace is composed of the furnace cover, the furnace door, the tapping trough and the furnace body. The furnace bottom and the furnace wall use alkaline


Refractory or acidic refractory masonry. Electric arc steelmaking furnaces are divided into ordinary power electric arc furnaces, high power electric arc furnaces and ultra-high power electric arc furnaces according to the transformer capacity per ton of furnace capacity. Electric arc furnace steelmaking is to input electric energy into the electric arc steelmaking furnace through graphite electrodes, and the electricity generated between the electrode end and the charge


The arc is the heat source for steelmaking. The electric arc furnace uses electric energy as the heat source, and the atmosphere in the furnace can be adjusted, which is extremely beneficial for smelting steel grades that contain more oxidizable elements. Soon after the invention of electric arc furnace steelmaking, it was used to smelt alloy steel and has been greatly developed.


With the improvement of electric arc furnace equipment and the improvement of smelting technology, the development of the electric power industry, the cost of electric arc furnace steelmaking continues to drop. Now electric arc furnace steelmaking is not only used to produce alloy steel, but also used to produce ordinary carbon steel. The proportion of output in the total steel output of major industrial countries continues to rise. Refractory materials used in electric arc furnaces. The electric arc furnace is a device that uses the electric arc generated between the electrode end and the charge as the heat source to perform electric diarl steelmaking. The development of electric arc furnace technology is the development of direct current electric arc furnace, furnace bottom gas agitation and furnace bottom tapping based on the use of high power. These technical achievements are inseparable from the development and application of new refractory materials. At the same time, the consumption of refractory materials is also reduced, and it is easy to control automatically. The electric arc furnace is composed of furnace roof, furnace wall, furnace bottom and tapping trough.


The knotted lining is made of well-sintered magnesia or fused magnesia. Pay attention to the cohesion of each layer during construction, and strive to keep the thickness and density of each layer consistent. In the early 1990s, China's 150t ultra-high power electric arc furnace bottom had a long life of 239 furnaces. There are working lining and lining under the ramming layer. The working lining is made of tar pitch combined with magnesia bricks, and the long-term lining is generally made of magnesia bricks. At the slag line on the upper part of the embankment slope, due to the severe erosion of the slag, the same or similar lining bricks as the hot spots of the furnace wall are now used, such as cast magnesia chrome bricks or combined with magnesia chrome bricks. The effect is better when the magnesia carbon brick is used for masonry, and the service life can be as high as 100 to 200 heats.

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