Requirements and Development Trends of Refractory Materials for Electric Arc Furnace Taps
2023年04月24日
The common tapping method for electric arc furnaces is slot tapping. Due to the large inclination angle of the electric arc furnace, this type of tapping corrodes refractory materials quickly, shortens the service life of the electric arc furnace lining, and affects steelmaking efficiency; Severe erosion of the ladle also affects its lifespan; It can easily lead to the diffusion of molten steel and oxidation, seriously affecting the quality of the steel; It is difficult to retain steel slag for tapping. Leaving steel slag for tapping can more fully utilize heat and reduce power consumption. Without slag entering the ladle, it can reduce the erosion of slag on refractory materials. However, slot tapping is not conducive to reducing refractory material loss and reducing power consumption
In order to overcome these shortcomings of slot tapping, the eccentric bottom tapping technology was developed in the late 1970s. China began using arc furnace eccentric bottom tapping technology in the 1980s. Eccentric bottom tapping has the following characteristics: firstly, the area of the water-cooled wall can be increased, thereby reducing the consumption and cost of refractory materials; 2、 Fast steel tapping, non dispersed flow, reduced air oxidation, can improve the quality of steel; 3、 Easy to achieve slag free steel tapping, reducing heat loss and erosion of refractory materials, reducing power consumption, and extending furnace lining life.
This tapping method, when the gate is closed, fills the tapping hole with filler from the top, and then the furnace material can be loaded for steelmaking. When the gate is opened, the filler and molten steel flow down from the steel outlet. The gate is a mechanical mechanism, and the filler is generally magnesium, silicon, and olivine refractory materials. Tail bricks are magnesium based, silicon carbide based, corundum silicon carbide carbon based, and magnesium carbon based refractory materials. Sleeve bricks are mostly made of magnesium and magnesium carbon refractory materials. Block bricks are generally oil immersed and combined with magnesium bricks. The gap between the sleeve brick and the seat brick is generally filled with magnesium sealant. During use, the main factors that affect its service life are the damage to the tail bricks and sleeve bricks, and their lifespan also represents the lifespan or replacement frequency of the steel outlet.
Analysis of the wear mechanism of refractory materials used for tapping holes
From the loss process of sleeve bricks and tail bricks at the eccentric bottom tapping hole, it can be seen that thermal shock peeling and steel erosion are the main causes of loss for fired magnesium sleeve bricks and tail bricks. For MgO-C sleeve bricks and seat bricks, the main reason is the formation of a loose decarburization layer due to the oxidation of carbon inside the magnesium carbon bricks. Then, the molten steel washes away the decarburization layer. Due to certain reasons, such as low supply power, lack of refining furnace and failure of certain equipment components, the operation is delayed, resulting in longer steel retention time in the electric arc furnace, higher steelmaking temperature, or poor filler performance. In this case, the filling material will be sintered, and when the tapping gate is opened, the tapping port will be blocked and unable to be tapped. At this point, it is necessary to use an oxygen blowing tube to blow oxygen and burn out the steel mouth, but this will generate local high temperature and overheating, causing the burned magnesium sleeve bricks to undergo thermal shock peeling and mechanical wear, resulting in high-temperature chemical corrosion and mechanical wear of the magnesium carbon sleeve bricks. This local damage is severe, so high-quality alkaline fillers should be selected, with the lowest possible tapping temperature and shorter steelmaking time.
Due to the exposure of the tapping groove outside the furnace, it is subjected to stronger thermal shock resistance and oxidation. At the same time, slag is produced during tapping, resulting in more severe erosion of the tapping groove by slag. This indicates that during the steelmaking process, the tapping groove is not only oxidized by air to form a loose decarburization layer, but also subjected to rapid cooling by cold air to cause internal thermal stress in the tapping groove,
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Electric fusion bricks and clay bricks are both refractory materials and have a wide range of uses in building materials. Today, Yuhua Electric Fusion Technology will introduce their differences to everyone:
Refractory bricks are abbreviated as firebricks. Refractory materials made by firing refractory clay or other refractory materials. Light yellow or brownish in color. Mainly used for building smelting furnaces, capable of withstanding high temperatures ranging from 1580 ℃ to 1770 ℃. Also known as firebricks. Refractory materials with a certain shape and size. According to the preparation process, it can be divided into fired bricks, unburned bricks, electric fused bricks (fused cast bricks), and fire-resistant and insulated bricks; According to shape and size, it can be divided into standard bricks, ordinary bricks, special bricks, etc. It can be used as high-temperature building materials and structural materials for building kilns and various thermal equipment, and can withstand various physical and chemical changes and mechanical effects at high temperatures. For example, refractory clay bricks, high alumina bricks, silica bricks, magnesium bricks, etc.
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