Based on the premise of returning surplus steel from steelmaking, under conditions such as compositional constraints, temperature constraints, and time constraints are all satisfied, analyze the weak links in energy-saving management in the steelmaking process, and formulate reasonable energy-saving targets for each link of the converter. Formulate optimization measures in combination with production demand and energy-saving demand.
Key words: converter surplus; steelmaking process; technical concept; feeding system
In the production process of the iron and steel industry, if the temperature is not up to standard, the composition of molten steel is unqualified, or the pouring quality is reduced due to mechanical equipment failure, it is necessary to add molten steel to the converter for blowing. This is surplus steel. There are obvious differences between recycled steel and non-recycled steel in steelmaking, namely the initial temperature in the converter, the initial composition of the slag, and the initial carbon content of the metal liquid. In view of this situation, the traditional normal steel blowing mode cannot be used when re-blowing the surplus steel of the converter, otherwise the surplus steel may be splashed during the smelting process, not only It will cause loss and consumption of steel materials, cause yellow smoke to overflow, and increase safety hazards in the steelmaking process, which is not conducive to the smooth progress of related work in the steelmaking process. In addition, the heat in the furnace during the recycling steelmaking process is also different from the conventional steelmaking process, which easily affects the control effect of the converter end point temperature and carbon content. Therefore, in order to promote the development and application of converter surplus steelmaking process, it is necessary to formulate optimization measures according to the actual situation to improve social and economic benefits.
High-efficiency, long-life compound blowing technology concept of converter
In the context of the current era, iron and steel enterprises can improve their core competitiveness and achieve healthy and stable development. They are working hard to reduce costs, improve the cleanliness of molten steel and strengthen management, and have achieved certain results. However, in reality, iron and steel enterprises are constrained in how to build a three-dimensional platform technology for high-efficiency and long-life composite blowing, and there are some problems that need to be solved reasonably in the process of realizing multi-objective collaborative optimization. Among these problematic situations, there are the following contradictions. First of all, it is reflected in the contradiction between the cleanliness of molten steel and the smelting efficiency of surplus steel. In the traditional concept of iron and steel smelting, the contradiction between these two processes is difficult to be unified and coordinated, making it difficult for the efficiency and quality of the actual production process to successfully achieve the ideal production target. Secondly, it reflects the contradiction in low oxidation control during the operation of the converter. Restricted by the iron and steel smelting production process and technology, the traditional “three highs and one low” operation mode is still used at this stage, which leads to serious restrictions on the dephosphorization of the converter. Low oxidation and low slag consumption will directly reduce the efficiency and quality of the converter dephosphorization process. Again, it is reflected in the contradiction between the converter bottom blowing and re-blowing. In the traditional concept, it is believed that high bottom blowing intensity will lead to an increase in the corrosion rate of the bottom of the furnace to some extent, thereby affecting the life of reblowing. In order to effectively prolong the life of re-blowing, it is necessary to reduce the intensity of the bottom blowing, and carry out centralized air supply and stirring work according to the original parts of the bottom blowing.
Steelmaking raw materials occupy an important position in steelmaking production and are the basis for the normal operation of the converter. Therefore, necessary tests must be carried out on them. At present, my country mainly uses two types of materials: domestically produced iron, low-alloyed slag remover and potassium permanganate as raw materials for steel; This steel should be selected for steelmaking when using a converter with a large amount of material but poor quality and high price. In the actual operation process, in order to ensure the effect of the converter smelting process, the relevant personnel must focus on the important control points in terms of temperature path and slagging law, and at the same time, they must also do a good job in the coordinated removal of multi-element oxidation. Due to the large differences in the combination of various parameters in the converter ironmaking process, such as different types of converters, different furnace charge structures, different feeding sequences, and different tapping operations, etc., it will lead to large fluctuations in the law of blowing reactions. . At the same time, in the blowing process, different thermodynamics and dynamics need to be used. Only in this way can the hammering time of the top and bottom of the converter be accurately controlled, thereby ensuring the high efficiency of precise smelting, and it is also positive for the maintenance of the bottom of the furnace. enhancement. While improving the quality and efficiency of iron and steel smelting, effectively control the amount of slagging generated during smelting, realize effective control of low oxidation, and promote the tapping temperature to match the high cleanliness standard. In addition, during the converter ironmaking process, relevant personnel also need to take measures to inhibit the peroxidation of slag, so as to reduce the maintenance difficulty of the life of the bottom blowing ventilation components. By coordinating the resolution of contradictions and traditional inertial thinking, it is possible to precisely control the various processes of the converter ironmaking process, so as to meet the production requirements of clean steel and lay a good foundation for the future development of iron and steel enterprises.
Current status of converter steelmaking process
Today, the converter ironmaking process has been widely used in the iron and steel smelting process, which has a certain impact on the efficiency and quality of ironmaking work. Since there are some problems in the application process of converter ironmaking, it is necessary to conduct an in-depth analysis of these problems and formulate a scientific and effective solution to the problems in combination with the actual situation, so that the converter ironmaking in the iron and steel smelting process can exert more potential positive influence. Converter tempering is to use the molten iron preheating method to heat the steel billet in the high temperature zone to make the temperature reach a certain high value, and then cool the molten iron to room temperature to ensure that no waste slag is generated during the metallurgical process. Since the steel production process and steelmaking technology have their own different characteristics. Therefore, for the same piece of ore, it uses the same material to produce two or more metal products; and for the same piece of raw ore, it is preheated on the same raw ore to make the temperature reach a certain high value.
Low dephosphorization rate in the early stage of blowing
In the converter ironmaking process, the dephosphorization records can be learned by taking samples from the inverted furnace. It is necessary to process the average dephosphorization rate to about 35% before the formal blowing. It will also show a low situation, which shows that the ideal slag dephosphorization utilization capacity has not been achieved. Observing the oxygen blowing test of the slag samples, it is found that there are many lime blocks in the slag. If the slag and lime blocks stick together, lime lumps will be formed, which will affect the dephosphorization reaction. When carrying out smelting work, slag removal is a very rigorous process problem. If the average dephosphorization rate is low, there will be certain difficulties in controlling the quality of steel, and the ideal state cannot be achieved smoothly.
The carbon and oxygen product height of molten steel at the end of blowing
In the converter ironmaking process, the efficiency and quality of iron and steel smelting can be reflected by the carbon-oxygen product value of molten steel. Therefore, it is necessary for relevant staff to take the carbon-oxygen product value as an important indicator when evaluating the smelting process. At the current stage, some iron and steel enterprises show high carbon and oxygen accumulation in the smelting process. Therefore, it is necessary to actively formulate more scientific and effective optimization measures according to the needs of iron and steel smelting to ensure that the carbon and oxygen accumulation value can be kept within a controllable range at all times.
Converter top blowing supply and bottom blowing gas supply
Today, the scope of application of the converter ironmaking process is relatively large, and various process technologies are becoming more and more mature. In practice, many iron and steel enterprises have not effectively applied the constant lance position blowing method in the process of using the converter ironmaking process to produce high-quality low-carbon steel, and the application effect and application frequency are limited. On the contrary, some small converter steelmaking plants will actively use the constant lance position blowing method for smelting work. In order to understand the slag melting situation more intuitively, it is necessary to formulate effective strategies in terms of nozzle parameter setting and lance position curve optimization. , Promote the improvement of the quality and effect of iron and steel smelting production.
Development of Converter Recycled Steelmaking Process
Converter does not leave slag
The converter steelmaking process uses the single slag method, the double slag method and the slag remaining method. In the process of applying the converter surplus steelmaking process, the final slag of the converter will contain a certain proportion of FeO, the proportion is 12%~18%. Using the slag retention method to operate can effectively increase the content of FeO in the early slag, so that the melting of the early slag can be properly advanced, reduce lime consumption, and improve metallurgical reaction capacity. In the smelting process of the remaining steel, if the slag retention method is used for operation and treatment, the FeO content contained in the slag will intensify the carbon-oxygen reaction to a certain extent, and it is easy to cause splashing accidents in the iron and steel smelting stage, increasing the safety of the smelting process risk. In actual work, relevant personnel are required to get out all the remaining residues in the furnace, so that no residues are left in the converter, and provide a reliable guarantee for the effect and safety of the subsequent steel smelting work.
Pour off part of the refining slag
There is more Al2O3 in the refining slag, and its alkalinity content is higher, which further increases the melting point of the refining slag to a certain extent. Under such circumstances, after entering the converter, the refining slag will encrust, causing the gas in the furnace to not be discharged smoothly. In this way, splashing will occur during blowing of surplus steel, which increases the probability of safety accidents. Therefore, in order to avoid this situation, the refining slag needs to be completely discharged before the converter.
Formulate the appropriate charging amount of molten iron and scrap steel
In the process of applying the converter steelmaking process, it is necessary to ensure that the composition and key temperature in the furnace reach the standard. This requires relevant personnel to refer to the weight of the remaining molten steel when deciding on the amount of molten iron and scrap steel. Generally, the ratio of molten iron to scrap steel is 10:1~12:1. For the carbon, silicon, manganese and other alloying elements in Huiyu steel, if all the content ratios are high, the lower limit needs to be taken, otherwise the lower limit should be taken. Adding the amount of recycled steel, molten iron and scrap steel together is the charging amount of a normal furnace. During the charging process, technical requirements must also be followed, and the loading of scrap steel, recycled steel and molten iron is strictly carried out.
Optimal feeding system
In the process of optimizing the feeding system, the loading amount of lightly burned dolomite must be clarified. In order to ensure the appropriate content of MgO in the slag, when adding light-burned dolomite, it accounts for about 40% of the amount of lime added compared with the amount of lime added. Secondly, when adding slagging material, choose a reasonable feeding method. Mix the molten iron and the remaining steel together. If the carbon content of the molten metal does not exceed 1%, the addition of light-burned dolomite and lime must be completed in one go. If it is higher than 1% when feeding, it is necessary to observe the decarburization reaction in time, and use reasonable means to reduce the carbon content of the molten metal. When the temperature is controlled to produce a strong deoxidation reaction, it indicates that the carbon content of the molten metal has been reduced to 1%. %the following. At this time, the deoxygenation reaction speed will gradually slow down, and the splashing situation is not easy to occur, so the link of suppressing the splashing situation can be omitted. In addition, because the carbon content is relatively low, the blowing time is also short. If the slag is added in batches, the blowing will be completed before the second batch is fully melted, resulting in waste of slag-making materials. Can not guarantee the economic benefits in the smelting process.
Application effect of converter recycling steelmaking process
Improve the quality of molten steel
Relevant personnel can obtain a standard basis when analyzing the steel type and quality of the surplus steel, and use this to determine the amount of slag and molten iron, which can effectively control the internal heat in the steelmaking process of the surplus steel and improve the hit rate of the converter end point , to prevent the phenomenon of molten steel peroxidation during normal operation, and effectively guarantee the quality of molten steel.
Through the reasonable application of technology, the phenomenon of splashing can be fundamentally avoided, and the difficulty of residue cleaning will be reduced to a certain extent, and personnel will devote more energy to the production process to improve the production efficiency of the enterprise. During converter ironmaking, in the high temperature zone, due to the characteristics of low gas and heat flux density, high temperature and high pressure, coking phenomenon is prone to occur in the process of converter steelmaking. Iron and steel enterprises should pay attention to this issue. Firstly, it is necessary to strictly control the quality of the smelting material entering the rolling process; secondly, it is necessary to strengthen the detection and temperature control of the content and acidity of molten iron in slag to ensure that the quality of steel products meets the requirements; thirdly, it is necessary to increase the refining speed and efficiency to increase productivity.
Reduce yellow smoke phenomenon
By developing the surplus steel blowing process, the smoke problem caused by splashing can be effectively reduced, which can ensure that the steel smelting process will not pollute the surrounding ecological environment, improve the economic benefits of the enterprise, and ensure social and ecological benefits .
Process optimization measures for converter steelmaking
Since the steelmaking process of steel mills mainly uses iron slag, in metallurgical production, iron and steel enterprises often use high-efficiency and highly automated converters. This not only saves energy and raw materials but also increases labor productivity. With the rapid development of my country’s economy. It has made important contributions to the sustained and healthy growth of my country’s national economy: firstly, our country is in the period of industrialization; secondly, our country is in the stage of socialist modernization; finally, it is the process of realizing socialization with Chinese characteristics. In the process of optimizing the converter steelmaking process, it is necessary Actively use advanced scientific concepts to set process parameters reasonably. First of all, it is necessary to measure the pressure loss of the pipeline. The purpose of this is to be able to understand various data information and formulate standards for the next work. At this stage, many iron and steel enterprises will produce high oxygen pipeline loss during smelting. Secondly, the water model test of the interaction between the oxygen jet and the molten pool is carried out. By observing the spattering in the iron and steel smelting process, it can be known that the degree of slagging during converter blowing is not ideal, and this situation is closely related to the phenomenon of metal spattering. If you want to solve this problem, you need to optimize the design of the nozzle parameters. Finally, optimize the blowing curve and improve the maintenance of breathable bricks. In the blowing process, the constant lance position operation can no longer meet the relevant requirements of the current high-quality blowing products. It is necessary to actively upgrade and optimize the process technology, and rationally use the method of grabbing the position curve to control the iron oxide content in the slag.
The converter steelmaking process is a widely used steelmaking technology. In order to further enhance the positive effect of the converter steelmaking process, it is necessary to formulate optimization measures for the converter steelmaking process. The use of technical means to improve production quality and efficiency ensures the economic and social benefits of the steel industry and brings favorable conditions for the stable development of the steel industry.