Production method of converter slagging agent

Abstract

The invention discloses a production method of a converter slagging agent, which comprises the following steps: S1, mixing electrolytic manganese slag with plant fiber, processing into particles with the particle size of 10-20mm by using extrusion granulation equipment, and transporting to a steelmaking production line for later use; s2, after molten steel subjected to LF refining is cast in a continuous casting machine, the pellets are added into a steel ladle, and then refining slag casting residues are poured into a slag tank; s3, repeating the operation until the slag tank is full of the refining slag; s4, slowly cooling the refining slag to 100 DEG C or below by adopting a slow cooling process for the slag tank filled with the refining slag, carrying out crushing and disintegration treatment, processing the refining slag to the granularity of 30-50mm, and then pulling slag blocks with the granularity of 30-50mm to a converter production line for later use through a screening system; and S5, converter smelting is started, when the first batch of slag auxiliary materials are added, the slag melting agent is added, the adding amount is 3-5 kg per ton of steel, and the other smelting processes are not changed.

Description

Technical Field

[0001] This invention relates to a method for producing a converter slagging agent. Background Technology

[0002] There are various types of slagging agents used in converter steelmaking processes. The most common include fluorite, iron ore, manganese ore, and bauxite. The main purpose of using slagging agents is to promote the dissolution of lime and improve smelting conditions. The basic principle is that certain oxides added to calcium oxide react with it, thereby lowering the melting point of calcium oxide to achieve the purpose of slagging and fluxing. The range of reduction in melting point caused by adding 1% of a certain substance to CaO is shown in the table below: ; Currently, there are four main types of fluorine-free composite slag agents in China: borate-based, CaO-Fe2O3-based, Al2O3-based, and MnO-based. In practical production applications, borate-based slag agents (with B2O5 as the main component) have limited resources and are relatively expensive; the preparation process of CaO-Fe2O3-based agents requires high-temperature equipment and is relatively complex; while the main minerals of Al2O3-based and MnO-based slag agents are common minerals widely distributed in China, thus they have the characteristics of sufficient supply and stable prices. These two types of slag agents have also been successfully put into industrial trials and applications.

[0003] According to the literature review, (1) Shen Jisheng, Zhao Weidong, Chen Shoujun, Zhu Wanjun, and Wang Xiang published a paper entitled "Research on Steelmaking Process of Using Flux for Slag Adjustment in Converter" in the 6th issue of Steelmaking magazine in 2017. The paper stated: "In order to solve the problems of large fluctuations in the composition of blast furnace molten iron, difficulty in achieving steady-state control and standardization of smelting operation in the molten iron smelting process, flux slag adjustment operation was introduced in converter operation. Application practice shows that after the converter uses flux slag adjustment operation, there is no splashing, no back-drying, and no sticking to the gun during the blowing process. It can reduce slag consumption by 9.3 kg / t and reduce metal blowing loss from 11.60% to 10.01%, achieving significant economic benefits and achieving the goal of smooth converter smelting and reducing production costs." (2) Tang Xiaohui and Deng Yong published a paper entitled "Jigang 45" in the 2nd issue of Metallurgy and Materials magazine in 2019. The paper, titled "Application of Economic Steelmaking Technology in Converters," includes the following statement: "The article introduces new ways to recycle waste from steel and aluminum plants. In order to reduce the cost of steelmaking processes, economical materials such as red mud balls, dust removal balls, and return slag are developed for converters. The application process of each material is tracked and explored. This not only reduces the cost of steelmaking processes but also makes a significant contribution to environmental protection, forming a circular economy production model."

[0004] As can be seen from the above literature, none of the literature mentions the process method for producing converter slagging agents using electrolytic manganese slag and LF refining slag.

[0005] Electrolytic manganese slag is the acid leaching residue produced during the electrolytic production of metallic manganese from manganese ore. It is a major solid waste from the electrolytic manganese industry. Because manganese ore often contains impurities such as Pb, Zn, Cu, Ni, and Cd, and the production process uses large amounts of ammonia, the main pollutants in electrolytic manganese slag are manganese and ammonia nitrogen, in addition to associated heavy metals. These pollutants are highly susceptible to migration into the surrounding ecosystem during long-term storage, posing ecological risks and ultimately harming human health. Statistics show that 1 ton of metallic manganese produces 3 to 12 tons of electrolytic manganese slag during production. Currently, the disposal of electrolytic manganese slag is mainly through open-air storage, with a comprehensive utilization rate of less than 10%. The main components of electrolytic manganese slag produced by a factory in southern Xinjiang Uygur Autonomous Region are shown in the table below: ; A review of literature (1) Xiao Xingyu, He Dejun, Chen Mengjun, and Liu Hui published a paper entitled "Research Status and Prospect of Comprehensive Utilization of Electrolytic Manganese Slag" in the 7th issue of Materials Reports in 2025. The paper states that "the large production volume and low comprehensive utilization rate of electrolytic manganese slag make its large-scale resource utilization a key problem restricting the sustainable and green development of the electrolytic manganese industry. At present, the comprehensive utilization of electrolytic manganese slag is mainly concentrated in low-end building materials products with low added value. With the decline of the building materials market, the resource utilization of electrolytic manganese slag is gradually transforming towards diversification and high added value." The paper systematically reviews the characteristics and hazards of electrolytic manganese slag, summarizes the basic status of comprehensive utilization of electrolytic manganese slag from three aspects: emission and utilization of electrolytic manganese slag, and relevant laws, regulations, policies and standards for comprehensive utilization, and focuses on The latest research progress of electrolytic manganese slag at home and abroad in the comprehensive recycling of valuable resources, preparation of glass ceramics-ceramic aggregates, preparation of building and road materials, ecological restoration and other aspects is summarized. The problems existing in the comprehensive utilization of electrolytic manganese slag are summarized and targeted suggestions are provided. It is pointed out that the efficient recycling of valuable resources, the use of high-value-added bulk building materials, ecological environment restoration, and soil-like ecological restoration are important development directions for the comprehensive utilization of electrolytic manganese slag in the future. (2) Li Jiale, Wan Tingyong, Ke Pingchao, Zhou Yipeng, and Xu Lingling, five authors, published a paper entitled "Research Progress on Harmless and Resource-based Treatment Technology of Electrolytic Manganese Slag" in the 7th issue of Inorganic Salt Industry in 2025. The paper states: "Electrolytic manganese slag (Electrolytic manganese slag) Manganese residue (EMR), rich in heavy metals (Mn, Cr, Pb) and ammonia nitrogen (NH3-N), has become a significant challenge hindering the green development of the manganese metallurgy industry. This paper introduces the sources, physicochemical properties, and environmental hazards of EMR from electrolytic manganese production processes, and systematically reviews the latest advancements in the harmless and resource-based treatment technologies for EMR. To address pollution control needs, gelation solidification, high-temperature solidification, and chemical solidification technologies achieve the stabilization and building material utilization of heavy metals and ammonia nitrogen in EMR through a multi-mechanism synergy; however, long-term environmental risks and carbon emission issues require further research. Regarding leaching processes, chemical leaching, bioleaching, and electric field-enhanced leaching technologies achieve the dual goals of harmlessness and resource utilization by selectively extracting valuable components; however, they face bottlenecks such as high acid consumption, long cycles, and toxic residues.

[0006] As can be seen from the literature review above, none of the literature mentioned the process method for producing converter slagging agents using electrolytic manganese slag and LF refining slag. Summary of the Invention

[0007] The purpose of this invention is to provide a method for producing a converter slagging agent, which utilizes steelmaking refining slag to treat electrolytic manganese slag, achieving the harmless transformation of electrolytic manganese slag without affecting the steelmaking process, and saving on the treatment cost of electrolytic manganese slag.

[0008] The technical solution adopted in this invention is a method for producing a converter slagging agent, which is implemented according to the following steps: S1. Mix electrolytic manganese slag with plant fiber. The electrolytic manganese slag and plant fiber are mixed in a mass percentage ratio of 95%:5%. Then, the mixture is processed into particles with a particle size of 10-20mm using an extrusion granulation equipment and transported to the steelmaking production line for later use. S2. After the molten steel refined by LF is poured into the continuous casting machine, the above pellets are added to the ladle, of which more than 200-350 kg of pellets are added for every ton of refining slag. Then the remaining refining slag is poured into the slag pot. S3. Repeat the above operation until the slag pot is full of refining slag; S4. The slag pot filled with refining slag adopts a slow cooling process to slowly cool the refining slag to below 100℃, and then crushes and disassembles it to process the refining slag into a particle size of 30-50mm. Then, through a screening system, the slag blocks with a particle size of 30-50mm are transported to the converter production line for use. The total amount of MnO+Al2O3+SiO2 in the slag blocks should be greater than 50%. S5. When the converter smelting begins, add the above slag-forming agent when adding the first batch of slag auxiliary materials. The amount added is 3-5 kg ​​per ton of steel. The rest of the smelting process remains unchanged.

[0009] After adding a small amount of plant fiber to the electrolytic manganese slag to form pellets, it is added to the hot LF refining slag. The residual heat and mineral structure of the refining slag are used to dehydrate, remove ammonia and desulfurize the electrolytic manganese residue. Then, during the slow cooling process of the refining slag, the components rich in aluminate and manganate are selected by screening process and used as slagging agents for converter resource utilization. The main functional components of the slagging agent are manganese oxide, iron oxide, silicon dioxide and alumina in the electrolytic manganese slag and alumina in the refining slag.

[0010] Technical principle of this invention: Through study and research, the inventors discovered that electrolytic manganese slag contains a certain amount of manganese oxide (MnO), which is itself a good slagging agent. Therefore, using electrolytic manganese slag as a converter slagging agent is feasible, mainly for the following reasons: During the converter blowing process, the initial slag mainly consists of FeO, SiO2, and a small amount of MnO. When lumpy lime comes into contact with the initial slag, because the slag and lime are wetted, the slag will penetrate into the pores and cracks on the lime surface. 2+ The diffusion rate in slag is greater than that in SiO4. 4- Therefore, Fe 2+The lime enters the lime block along pores and cracks, forming a low-FeO CaO (FeO) solid solution and a high-FeO FeO-CaO liquid phase. This liquid phase mixes with the primary slag, increasing the (CaO) content in the slag, and the lime begins to dissolve in the slag. Simultaneously, SiO4 that failed to diffuse into the lime block... 4- Reacting with CaO, CaO·SiO2 (C2S) and 3CaO·SiO2 (C3S) coating layers are formed on the surface of the lime block. Both (C2S) and (C3S) are high-melting-point substances; (C2S) has a melting point of 2130℃, while (C3S) is a partial melting point compound with a decomposition temperature of 2070℃. These coating layers separate the lime block from the slag, slowing down the dissolution rate of the lime. Therefore, reducing the thickness of the coating layer is beneficial to increasing the dissolution rate of the lime. The results show that the coating layer formed on the outer surface of the lime in contact with the slag is C2S, while the inner surface is C3S, which is the main reason for the hindered lime dissolution reaction.

[0011] In slag, MnO mainly reacts with SiO2 and Al2O3 to form low-melting-point compounds (see table), which lowers the slag melting point. Furthermore, since some SiO2 combines with MnO, the possibility of forming high-melting-point C2S and C3S is reduced. Therefore, increasing the amount of MnO in the slag should have a good and sustainable slag-forming effect.

[0012] For the reasons mentioned above, many steel mills add manganese ore as a slagging agent during converter steelmaking, which also has a good slagging effect. The main component of manganese ore slagging is (MnO), and the reaction in the furnace is as follows: (MnO)+(SiO2)= (MnO·SiO2) (MnO·SiO2)+2CaO)=(2CaO·SiO2)+(MnO) ; (MnO) exists stably in slag and can increase slag fluidity, which plays a positive role in effectively inhibiting slag drying. In addition, (MnO) can shorten the reaction time of acidic slag in the furnace, providing conditions for early slag formation and slowing down the erosion of the furnace lining.

[0013] As lime continues to melt, (MnO) exists in a free state in the slag, promoting slag fluidity. The slag-forming agent also contains a large amount of iron oxide, which can reduce the formation of (2CaO·SiO2) on the lime surface and make the formed (2CaO·SiO2) loose, which is conducive to lime dissolution and avoids re-drying in the middle of converter smelting.

[0014] The refining slag produced during the production of aluminum-killed steel contains 20%–35% Al2O3, which is an excellent slagging agent for converters. When added to the converter, in the presence of Fe2O3 in the converter slag, Al2O3 can form various compounds or solid solutions with very low melting points, such as 4CaO·Al2O3·Fe2O3 (C4AF, calcium aluminoferrite, melting point 1415℃). The melting point of the Al2O3-Fe2O3 solid solution is below 1370℃. Phase diagram calculations show that in slag with a basicity of 3 and FeO of 20%, 6% Al2O3 can lower the liquidus temperature by 130℃. Therefore, the Al2O3 content in the converter slag should generally be less than 1.5% to achieve slagging and enhance slag splashing protection. Thus, the refining slag produced during the production of aluminum-killed steel can be used as a slagging agent in converters after processing.

[0015] The innovations of this invention are as follows: 1. The inventors discovered that sulfides and ammonia nitrogen compounds in electrolytic manganese slag, when added to high-temperature liquid refining slag, cause the sulfides to form SO2 and escape, while the ammonia nitrogen compounds dissociate, rapidly achieving the harmless transformation of the two harmful substances; 2. After electrolytic manganese slag and liquid refining slag are mixed and melted, the residual sulfides in the electrolytic manganese slag form a new mineral phase, which enters the silicate minerals in the refining slag; 3. The manganese oxide in the electrolytic manganese slag reacts with the aluminates in the refining slag to form low-melting-point minerals, which are excellent composite slagging agents; 4. To achieve the separation of the slagging-functional components from the silicates in the refining slag that do not have slagging function, the inventors use a slow cooling process to treat the refining slag. During the slow cooling process, the dicalcium silicate phase transformation in the refining slag causes the dicalcium silicate to pulverize, forming powder. Through a sieving system, the separation of the slagging-functional components and the silicate components can be achieved.

[0016] The beneficial contributions of this invention are as follows: 1. By using steelmaking refining slag to treat electrolytic manganese slag, the harmless transformation of electrolytic manganese slag is achieved without affecting the steelmaking process, saving the treatment cost of electrolytic manganese slag, which is of great significance to social development; 2. By using electrolytic manganese slag and refining slag to replace the traditional slag-forming agent in converters for resource utilization, the cost of steelmaking is reduced, the total amount of solid waste is reduced, and the environmental protection significance is significant. Detailed Implementation

[0017] The implementation of this invention is illustrated using an 80-ton converter + LF + continuous casting machine production line as an example: A method for producing a converter slagging agent, comprising the following steps: S1. Mix electrolytic manganese slag with plant fiber. The electrolytic manganese slag and plant fiber are mixed in a mass percentage ratio of 95%:5%. Then, the mixture is processed into particles with a particle size of 10-20mm using an extrusion granulation equipment and transported to the steelmaking production line for later use. S2. After the molten steel refined by LF is poured into the continuous casting machine, the above pellets are added to the ladle, of which more than 200-350 kg of pellets are added for every ton of refining slag. Then the remaining refining slag is poured into the slag pot. S3. Repeat the above operation until the slag pot is full of refining slag; S4. The slag pot filled with refining slag adopts a slow cooling process to slowly cool the refining slag to below 100℃, and then crushes and disassembles it to process the refining slag into a particle size of 30-50mm. Then, through a screening system, the slag blocks with a particle size of 30-50mm are transported to the converter production line for use. The total amount of MnO+Al2O3+SiO2 in the slag blocks should be greater than 50%. S5. When the converter smelting begins, add the above slag-forming agent when adding the first batch of slag auxiliary materials. The amount added is 3-5 kg ​​per ton of steel. The rest of the smelting process remains unchanged.

Claims

1. A method for producing a converter slagging agent, characterized in that... Follow these steps: S1. Mix electrolytic manganese slag with plant fiber. The electrolytic manganese slag and plant fiber are mixed in a mass percentage ratio of 95%:5%. Then, the mixture is processed into particles with a particle size of 10-20mm using an extrusion granulation equipment and transported to the steelmaking production line for later use. S2. After the molten steel refined by LF is poured into the continuous casting machine, the above pellets are added to the ladle, of which more than 200-350 kg of pellets are added for every ton of refining slag. Then the remaining refining slag is poured into the slag pot. S3. Repeat the above operation until the slag pot is full of refining slag; S4. The slag pot filled with refining slag adopts a slow cooling process to slowly cool the refining slag to below 100℃, and then crushes and disassembles it to process the refining slag into a particle size of 30-50mm. Then, through a screening system, the slag blocks with a particle size of 30-50mm are transported to the converter production line for use. The total amount of MnO+Al2O3+SiO2 in the slag blocks should be greater than 50%. S5. When the converter smelting begins, add the above slag-forming agent when adding the first batch of slag auxiliary materials. The amount added is 3-5 kg ​​per ton of steel. The rest of the smelting process remains unchanged.