The ultimate goal of operation and management of steel mills is to control costs and ensure the quality of good products, and ultimately obtain the greatest economic benefits. For steel mills, the consumption of refractory materials is an important measure of the technology and economy of steel enterprises. standard. With the increasing demand for steel in the current market, how to reduce the cost of the entire iron making plant and obtain higher economic benefits through the selection of refractory materials has always been a question of iron making. Only by continuously strengthening the fine selection of refractory materials can the cost and material consumption of iron and steel enterprises be effectively reduced, and can help iron and steel enterprises actively respond to the concept of green development in today's era, realize industrial green development, and ultimately improve economic and social benefits.
1. Preliminary preparation for the selection of refractory materials
Refractory materials generally refer to non-metallic materials with a refractoriness above 1580℃. Refractory materials include natural ores and products made according to certain purpose requirements. They have strong high temperature resistance characteristics and are manufactured by various high temperature equipment. Important material. Refractory materials can be viewed from a wide range, including shaped refractories and unshaped refractories. If further subdivided, there are 8 to 10 ways to classify refractory materials. Therefore, when selecting refractory materials, it is also the same technology and knowledge .
1.1 Specify where refractory materials are to be used in the kiln (purchasing direction)
The factory engineer must clearly indicate which part of the kiln is to be used before purchasing refractory materials. Due to the diversification of refractory materials, combined with different factors such as the shape, temperature, and ease of construction of various parts of the kiln, the basic direction of purchasing refractory materials depends on these factors. Only a good direction is determined. An accurate positioning and division can save the time when selecting materials to a large extent, and can make targeted purchases.
1.2 Distribution management of the purchaser's warehousing (placement of materials)
After purchasing refractory materials, it is necessary to arrange the storage place of the goods before the goods arrive. This is also particular. For example, if you purchase two types of products: shaped refractory materials (refractory bricks, etc.) and unshaped refractory materials (refractory castables, etc.). If it is not on the same day, try not to place it in the open field to prevent rain and moisture, which may cause changes in the physical and chemical properties of refractory materials. The other is the order of using materials, so that the order of using the materials first is the outside, and then the materials are the inside [2]. It is also necessary to consider the convenience of the truck during construction operations. Especially for refractory castables, no breakpoints should be allowed during construction to prevent the situation where there is anxious use on the one side and the other side cannot be transported to the construction site.
1.3 About the procurement of unshaped refractory materials
Unshaped refractory materials should have no inventory management as far as possible (unless they are ready for use), such as refractory castables (plastic, spray paint, etc.) in unshaped refractory materials. Due to the need for refractory castables to reach the most ideal state of construction and use, the long-term backlog of inventory
It will cause the material's physical and chemical properties to be reduced or unstable by external environmental factors. Therefore, in addition to no backlog of funds, no-inventory management of unshaped refractory materials is more important to ensure the optimal use effect.
1.4 Construction technical issues (important links)
In terms of construction, standardized construction operations can be carried out in accordance with the technical instructions given by the refractory manufacturer. The construction should not be repaired or reworked, so as to avoid unnecessary waste, no loss of repair, and no broken chain of the production line. In the process of construction, it is necessary to continuously improve the construction technology. Only by continuously standardizing the operation and using refractory materials reasonably and effectively can the economic benefits of the steelmaking plant be better guaranteed.
2. Measures to improve the economic selection of refractory materials in steel mills
2.1 Economical refractory control technology for the converter itself
The working conditions of the various parts of the converter are affected by operating factors and the corrosion rate of the furnace lining is relatively uneven. The converter causes damage to the trunnion, slag line and tap hole on both sides of the converter. Although the other parts are still relatively intact, the whole is still in the end. Can not continue to use. According to the damage characteristics of each part of the furnace lining, lining bricks of different grades and qualities are then selected to comprehensively build the furnace, and finally the damage reaches a basic balance. The iron and steel plants in my country mainly use magnesia-carbon bricks as furnace lining materials when they carry out converters. Since the slag line is in contact with molten slag for a long time, it is required to build magnesia-carbon bricks with excellent slag resistance. On the charging side, magnesia carbon bricks with strong slag resistance, high temperature resistance and thermal shock resistance should be selected for the direct impact and erosion of slag and molten steel and charged scrap and molten iron during oxygen blowing. According to the different degree of erosion, the hearth and the bottom of the furnace are eroded slightly, so ordinary magnesia-carbon bricks can be selected. For severely damaged ones, such as when top-bottom conversion technology is used, the damage is serious. High-grade magnesia carbon bricks with better oxidation resistance, better thermal shock resistance and higher temperature resistance should be selected. In order to better meet the needs of bottom-blowing transformation, the embedded furnace bottom structure, in order to be able to make the joints more secure, it is necessary to design and develop "embedded furnace bottom", in the bottom of the furnace bottom and the bottom of the furnace body masonry At this time, the bottom blow base bricks must be fixed first, and a layer of 100mm magnesia carbon bricks should be laid flat upwards. When the bottom blow is used for masonry, the height of the masonry should be 100mm higher than the plane of the furnace bottom masonry. In order to make the steel mouth structure more stable, it is necessary to continuously improve the brick design of the tap hole large bricks, and change the integral cylindrical tap hole sleeve bricks that were originally cast to the segmented multi-edge machine pressed magnesia carbon bricks. . At the same time, it is necessary to rationally configure and use high-life and large-area refills according to the time when the furnace is shut down, so as to increase the life of the furnace, reduce the consumption of refractory materials, and ultimately reduce the cost of iron and steel enterprises.
2.2 Low-cost molten steel refining and filling and ladle nozzle flow control technology
Ladle refers to an important container for holding and transporting molten steel between steelmaking and continuous casting. The sliding nozzle of the ladle is an important part of the ladle system. It directly relates to whether the molten steel in the entire ladle can be safely and stably injected into the middle. Only by continuously accelerating the hot turnover of the ladle and reducing the labor intensity of the packaging workers, it is necessary to continuously reduce the production cost, reduce the consumption of refractory materials, and ultimately improve the production efficiency and obtain the greatest economic benefits.
Sometimes there will be leakage of steel between the upper runner brick and the upper runner brick. The main reason is that the upper runner brick creeps into the cavity of the seat brick, and the fire mud in the contact place between the upper runner brick and the upper runner brick Relatively thick and sparse, this will cause the air in the created gap to diffuse, and finally cause the aluminum-carbon fire mud to be oxidized, which reduces the strength, and the gap will continue to widen, and the solution will leak steel. At the time, the leakage of steel is due to the deformation of the connecting plate, which makes it loose. Once the loosening occurs, the molten steel will traverse laterally between the contact surfaces . In order to prevent the occurrence of steel breakout, it is necessary to improve the quality of the skateboard in accordance with the smelting conditions of the iron smelter, improve the oxidation resistance and corrosion resistance of the skateboard, and strictly control the amount of water added to the fire mud to ensure that the fire mud is loaded. , It is exactly flush with the bowl mouth of the upper skateboard tile, and it is better to be 2mm~3mm lower than the bowl mouth. In order to prevent loosening of the connecting screw between the mounting plate and the connecting plate, the ability to resist deformation can be increased, the thread connection method can be changed, and the inner and outer countersunk countersunk screw connection of the bag can be changed.
2.3 Economical selection of lining materials for mixing furnace lining and molten iron ladle
The main function of the mixer in the storage of molten iron is to maintain a constant temperature, which facilitates the production of the steel plant and ensures the smooth completion of the converter operation. At present, the mixing furnace is chemically corroded due to long-term storage of molten iron and long-term erosion by the lining material, which shortens the service life of the mixing furnace. In the selection of refractory materials, the inspection of the damage condition of the mixer mainly depends on four aspects: the iron receiving hole, the area of the tapping slag line and the vault, the improvement of the technology of the jacket casting repair of the mixer, and the continuous improvement of the temperature. The overall modification technology of the tap hole can effectively improve the service life of the mixing furnace. The comprehensive lining technology adopted in the mixing furnace lining adopts different refractory materials according to different parts, which can largely eliminate the need for lining the furnace. The weakest link in masonry can help steel plants reduce production costs and improve production efficiency.
2.4 Economical selection of steel grades for continuous casting refractories
Refractory materials for continuous steel casting mainly include steel drums, tundishes, and integral stopper rods, sliding nozzles and shrouds that are matched with them. The continuous casting process is the last step of the steelmaking process. The tundish is the last step of the process. The last container for direct liquid steel, the refractory material used in the tundish is directly related to the quality of the liquid steel and also directly related to the service life of the tundish. In order to extend the service life of the tundish, increase the life of the nozzle, reduce the probability of bag penetration in the impact area, and improve the erosion resistance of the working lining, at the same time, it is necessary to continuously optimize and adjust the structure, continuously improve the existing baking process, and strictly stipulate The operation process and the standardization of the work order of the staff are very helpful to the development of the steel making plant.
3. Conclusion
There are many reasons for the consumption of refractory materials. Through a detailed analysis of the reasons for the consumption of refractory materials, in order to enable steel plants to use refractory materials to ensure quality and production efficiency, while reducing the cost of using refractory materials, A reasonable and efficient use.
Iron making plants can use the converter body economic refractory material control technology, low-cost molten steel refining and filling and ladle nozzle flow control technology, the economic selection of mixer lining and molten iron ladle lining materials, and the economic selection of continuous casting refractory materials by steel types. Continuously reduce the consumption of refractory materials, reduce economic costs, and help steelmaking plants to obtain maximum economic benefits.
