Supplier of refractory bricks for tapping port of metallurgical steelmaking BOF
The taphole brick is the channel for the molten steel from the converter to flow to the ladle. It is in direct contact with the molten steel, and its life directly affects the steelmaking rhythm of the converter. From the structural point of view, the taphole brick is divided into integral brick (also called taphole pipe brick) and split brick; the integral brick is generally formed by isostatic pressing, and the split brick is formed by machine pressing. In order to facilitate installation on the converter, the taphole brick is often assembled into one with a steel pipe and a flange.
Principle Introduction : The taphole is the channel for molten steel to flow from the converter to the ladle, and it is one of the key refractory components of the converter. The taphole enables the separation of slag during the tapping process, reduces the pollution of molten steel caused by slag flowing into the ladle, and also reduces the burning of alloy elements; at the same time, the steel flow at the taphole strongly stirs the molten steel in the ladle, promotes the floating of slag inclusions and deoxidation products, which not only affects the production efficiency of molten steel smelting, but also affects the quality of molten steel.
Classification : The tapping hole of the converter can be divided into machine pressing and isostatic pressing in terms of forming methods. The machine pressing tapping hole has a large volume density and high strength; the isostatic pressing tapping hole has a uniform structure and uniform internal stress distribution. In terms of structure, it can be divided into split type and integral type. The split type is easy to install, but due to the gap in the product, it is easy to leak steel during use; the integral type is heavy and inconvenient to install, but because the product is a whole without gaps, it is not easy to leak steel. The choice of production method or structure of the tapping hole should be considered comprehensively in terms of use and installation.
Structure : The steel outlet is generally composed of steel outlet seat bricks and sleeve bricks (also called tube bricks). 1，Steel outlet brick: The tap hole seat brick is a brick that is placed outside the sleeve brick. Its function is to protect the sleeve brick and to support the converter brick when the sleeve brick is replaced and drilled, so that the sleeve brick can be replaced easily. Common seat bricks include pre-formed fixed products and bricks directly built on site. The split and integral tap hole seat bricks are pre-formed. When they are built, they can be directly installed after being assembled with the sleeve bricks. There are few steel leakage channels and a high safety factor. The brick-built tap hole seat bricks are generally built with working layer bricks in the converter shell, and permanent layer magnesium bricks are built on site in other places. The surrounding area is filled with ramming materials. The structure is relatively loose, with many steel leakage channels, but the cost is relatively low. The prefabricated tap hole seat bricks are generally square or round in shape, and the inner holes are all round. The size of the inner hole is 40~100mm of the outer diameter of the sleeve brick. 2，Steel outlet sleeve brick: The tap hole brick is the channel for the molten steel from the converter to flow to the ladle. It is in direct contact with the molten steel, and its life directly affects the steelmaking rhythm of the converter. In terms of structure, the tap hole brick is divided into integral brick (also called tap hole pipe brick) and split brick; the integral brick is generally formed by isostatic pressing, and the split brick is formed by machine pressing. In order to facilitate installation on the converter, the tap hole brick is often assembled into one with a steel pipe and flange.
Damage mechanism ：1，Oxidation of furnace gases: From the time when molten iron is charged into the converter to the blowing process, the tapping port is in a high-temperature oxidizing atmosphere. The furnace gas generated during the blowing process contains a large amount of CO. When it is discharged from the tapping port, a C-O reaction occurs, forming a decarburized layer on the inner wall surface of the tapping port, which directly causes damage to the tapping port. 2，Friction damage and mechanical scouring damage of molten steel and slag: When tapping steel, the tapping port has to withstand the huge pressure of the molten steel in the converter. At the same time, when the molten steel and slag flow out of the tapping port, they rub and scour against the inner wall of the tapping port, directly causing mechanical damage to the inner wall of the tapping port. 3，The tapping temperature is generally 1680~1710°C. Under the action of high-temperature molten steel, the material of the tapping port will soften, significantly reduce its strength, and even melt, causing damage to the tapping port.
Measures to increase life expectancy ：Measures to increase the life of the taphole include: 1，Hot-exchange tapping process optimization: The main problems of the converter tapping hole heat exchange process are: the tapping hole expansion time is long; the tapping hole is fixed by manual use of steel pipes; the tapping hole filler is filled with a converter spray gun. In response to these problems, the drill bit of the reamer was first optimized to shorten the drilling time and improve the drilling quality; secondly, a steel pipe was fixed on the inner wall when making the tapping hole sleeve bricks, which accelerated the replacement time of the sleeve bricks; finally, a special spray gun for the tapping hole was designed and used to improve the speed and quality of filling. Through these measures, the time for replacing the tapping hole is greatly shortened, the temperature in the furnace and the tapping hole shape are guaranteed, thereby ensuring the sintering effect of the steel mouth filler, laying the foundation for improving the life of the tapping hole. 2，Optimize the filling performance in the tapping hole：Poor quality of taphole filler can easily lead to air gaps around the taphole bricks, which will increase the damage rate of the taphole. Through experiments, special taphole fillers with high magnesium oxide content, good fluidity and fine particle size are used to ensure that the gap between the taphole bricks and the bricks can be filled, sintered evenly and with good sintering effect. 3，Reduce the tapping temperature: The main measures to reduce the tapping temperature include online and offline ladle baking, covering the ladle and tundish for insulation, using better insulation, and achieving full protection pouring of the continuous casting machine and low superheated steel pouring. Through the above measures, the tapping temperature is reduced by an average of 15°C to below 1690°C. The significant reduction in tapping temperature reduces the scouring and erosion of the tapping port by high-temperature molten steel and slag, effectively increasing the service life of the tapping port. 4，High carbon steelmaking technology: By promoting high-draw carbon steelmaking technology, the oxidizing properties of the final molten steel and slag are effectively reduced, and the oxidation erosion of the tapping port by the molten steel and slag is alleviated, creating conditions for increasing the life of the tapping port. 5，Slag blocking and slag protection technology at the tapping port: After steel is tapped, a slag stopper is used to block the steel outlet to reduce the corrosion and oxidation of the steel outlet by furnace gas and slag during the smelting process. When steel is almost finished tapping, a slag stopper is used to block the steel outlet to reduce the amount of slag and reduce the scouring and erosion of the steel outlet by slag. The slag protection technology is promoted. After the slag splashing furnace is protected, the slag is poured from the steel outlet surface. When the slag passes through the steel outlet, part of it adheres to form a slag layer to protect the inner wall of the steel outlet.
Taphole maintenance：1，During use, when uneven erosion of the slag layer occurs on the tapping side (such as pits around the tapping port and on the tapping surface, and unevenness around the tapping port), change the previous mode of repairing by simply relying on bag change time to achieve timely repair. 2，The steel flow should not be scattered, slag should not be dropped, the steel control time should not be more than 20 seconds, and the steel can be discharged cleanly; and the quality of each repair should be able to last for more than 16 hours. 3，When encountering the phenomenon of unclean steel, the furnace must be stopped immediately for processing.
Anshan justhigh refractory has 11 years of and production experience in the field of magnesia carbon bricks, aiming to provide customers with solutions for lining refractory solutions and refractory material supply for ladles, torpedo tanks, converters, ladles, tundishes, etc. in the steelmaking process. Our end customers are located in Asia, the Middle East, Europe and other countries. At the same time, our products have been recognized by customers. We have a strong technical R&D team, professional production lines and high-quality after-sales service, so you will not have any worries in the entire refractory procurement process.
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