Method for converter steelmaking by using rectification residues as exothermic agent

Abstract

The invention discloses a method for utilizing rectification residues as an exothermic agent in converter steelmaking, which aims at composition characteristics of rectification (distillation) residues generated in a coal processing process, combines a process technology of converter production and application of cold-bonded pellets, and uses the rectification (distillation) residues generated in the coal processing process as a binder and the exothermic agent to prepare the converter steelmaking by using the rectification residues as the exothermic agent. After being pelletized with steel slag fine powder and iron oxide scale as main raw materials, the raw materials are used as cold-bonded pellets in the converter steelmaking process for resource utilization, chemical heat provided by refined (distilled) residues generated in the coal processing process in the converter oxidation process is utilized, chemical heat needed by the reduction reaction of the cold-bonded pellets is balanced, and the converter steelmaking technological process is optimized.

Description

Technical Field

[0001] The invention relates to a method for utilizing rectification residue as a heating agent in converter steelmaking. Background Art

[0002] The distillation process of coal processing produces a variety of residues containing different types of organic matter and small amounts of heavy metals. These residues are potentially harmful to the environment and humans and are included in the national hazardous waste list. The list of hazardous wastes generated during coal processing in the 2025 National Hazardous Waste List is shown in the table below: ; The main harmful substances in the distillation residues produced during coal processing include: polycyclic aromatic hydrocarbons, acetophenone, styrene dimer, phenol and cumylphenol, alkenylbenzene, alcohols, and heavy metal compounds containing Cr, Ni, Cu, etc.

[0003] Literature review (1) Qiu Zegang, Li Zhuangzhuang, and Li Zhiqin published a paper titled "Research Progress on Conversion and Utilization Technology of Medium and Low Temperature Coal Tar" in the 4th issue of "Acta Petrolei Sinica" in 2024. The paper states that "With the development of coal tar deep processing technology, the comprehensive utilization of medium and low temperature coal tar has attracted attention. The current research status of medium and low temperature coal tar utilization at home and abroad is introduced, and the separation, hydrogenation and modification of medium and low temperature coal tar, production of fuel oil, special oil products and high-value chemicals, coal tar blending and hydrogenation, and coal tar pitch utilization are reviewed and analyzed. Based on the composition characteristics of medium and low temperature coal tar fractions, a technical route of "graded conversion and utilization" of medium and low temperature coal tar is proposed, making full use of its molecular characteristic structure and studying the use of efficient catalysts to make coal tar Directed conversion into target products. This provides a diversified, high-value and refined approach for the efficient and clean utilization of coal tar." The article does not mention the resource utilization of the refined (steamed) distillation residues produced during coal processing in the steelmaking industry; (2) He Xinfu, Gao Fan, Wu Hongju, and other authors published a paper entitled "Research Progress on Hydrogenation and Saturation Reaction of Polycyclic Aromatic Hydrocarbons in Oil-Rich Coal Tar" in the 7th issue of "Coalfield Geology and Exploration" in 2024. The article states that "coal tar is a liquid product of the low-temperature pyrolysis and high-temperature coking process of coal. According to statistics, my country's annual coal tar production reaches 26 million tons. Coal tar contains a large amount of polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, fluorene, anthracene, phenanthrene, and pyrene. Compounds are one of the important raw materials for separating and extracting aromatics or hydrogenating to produce liquid fuels. Common coal tar hydrogenation technologies for producing fuel oil include cutting fraction hydrogenation, delayed coking hydrogenation, full fraction hydrogenation, wide fraction hydrogenation, suspended bed hydrogenation, and boiling bed hydrogenation. By selecting appropriate process technologies, hydrogenating the heavy components of coal tar can improve the utilization efficiency of coal tar resources and the quality of fuel oil. "The content of the article does not mention the relevant content of the resource utilization of the refined (steamed) distillation residues produced during coal processing in the steelmaking industry; (3) Hui Jun, Sun Haocheng, Chen Junyu, Liu Chunyang, and four authors in 2023 No. 1 A paper titled "Research Progress on the Resource Utilization of Phenol Tar" was published in an issue of the journal Contemporary Chemical Industry. The paper states, "Phenol tar is a common hazardous waste produced in phenol / lactone production plants. It is produced in large quantities and has a complex composition. Blending and outsourcing are traditional disposal methods for companies, and research on its recycling is relatively limited. This review reviews recent progress in the resource utilization of phenol tar from the perspectives of synergistic utilization of units and extraction of high-value components. Currently, the primary utilization of phenol tar is as a partial feedstock for heavy oil processing plants and through continuous distillation to recover organic monomers. Other methods lack in-depth research." The paper also fails to mention the resource utilization of distillation residues generated during coal processing in the steelmaking industry.

[0004] According to the above literature, the distillation residue produced during coal processing has complex composition and large fluctuations in composition, making it a hazardous waste that is difficult to treat.

[0005] The steelmaking and rolling processes of steel companies both generate a certain amount of iron-containing dust and sludge, the two most abundant of which are iron oxide scale and steel slag fines. Using dry powder pelletizing at room temperature to pelletize these slag fines and then use them as raw materials for converter steelmaking is a mature process known in the industry as cold pelletizing technology.

[0006] The primary purpose of using cold-set pellets in converter steelmaking is to recover iron-containing materials. The iron oxide in the pellets is used to deslagging and balance the chemical heat of converter steelmaking. Currently, the amount of cold-set pellets used in converter steelmaking is less than 50 kg per ton of steel. This limitation is primarily due to the fact that the iron oxide in the pellets absorbs a significant amount of chemical heat during the reduction process, affecting converter temperature control.

[0007] References (1) Zhang Qingxue published a paper titled "Research on the Application of Medium-Temperature Consolidation Pellets of Steelmaking Converter Dust Sludge" in the 10th issue of "Steel" magazine in 2005. The paper states: "In order to understand the smelting performance of medium-temperature consolidation pellets of converter dust sludge in converters, a production test was conducted. In the test, the composition of molten iron, the carbon, phosphorus, sulfur content of molten steel at the end, and the slag data under normal production and test conditions were collected, and the comparison and data regression were carried out. The desulfurization and dephosphorization capacity, slag formation time, oxygen supply capacity and iron recovery under normal production and test conditions were analyzed. The test showed that the application of dust sludge pellets as slagging agent can accelerate the formation of initial slag and improve the desulfurization and dephosphorization capacity of converter slag; it can provide a certain amount of oxygen, Recover some iron elements;” The article does not mention the content of using the refined (steamed) distillation residues produced in the process of coal processing in converter steelmaking as resources; (2) Li Weidong, Sun Qun, Wang Xianghui, Ding Yong, Wang Guoqing, five authors published a paper entitled “Application of Iron-Carbon Composite Pellets in Converter Steelmaking” in the third issue of Angang Technology magazine in 2011. The article states that “In order to realize the application of iron-carbon composite pellets in converter steelmaking, the effect of the addition method and amount of iron-carbon composite pellets on the smelting results was studied. The results show that iron-carbon composite pellets can be used as slagging agents or cooling agents, which can stabilize the sulfur recovery amount in the converter. When used as slagging agents, iron-carbon composite pellets can shorten the slagging time, improve the dephosphorization capacity of converter slag, and recover some iron elements; when used as cooling agents, they can replace some cooling agents such as ores.” The article also does not mention the content of using the refined (steamed) distillation residues produced in the process of coal processing in converter steelmaking as resources; In summary, there is currently no process for resourceful utilization of the distillation residues produced during the coal processing process in converter steelmaking. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for utilizing distillation residue as a heat-generating agent in converter steelmaking, which can make large-scale use of the distillation residue produced by coal chemical enterprises as a heat-generating agent for converter steelmaking, thereby solving the problem of resource utilization of the distillation residue produced by coal chemical enterprises.

[0009] A method for using distillation residue as a heat-generating agent in converter steelmaking is implemented according to the following steps: S1. First, the distillation residue produced by a coal chemical enterprise is transported to the dry powder pelletizing production line for use; S2, transporting the steel slag powder and iron oxide scale to the dry powder pelletizing production line for use; S3, mixing the distillation residue with steel slag powder and iron oxide scale in a ratio of 40%:40%:20% by mass, and pressing them into 30-50 mm pellets using a high-pressure dry powder pelletizing machine; wherein the carbon content of the pellets is greater than 20%, and TFe>40%, and then transporting them to the converter production line for use; S4. During the converter smelting process, the pellets in step S3 are added to the converter as cold-solidified pellets in the early and middle stages of smelting. The adding process is consistent with the traditional process, and the added amount is increased by 15% compared with the amount of traditional cold-solidified pellets. The rest of the smelting process remains unchanged.

[0010] The inventor discovered the following scientific phenomena through experiments and research: 1. At the end of the converter blowing process, the molten steel and slag temperatures are the highest in the converter steelmaking process, ranging from 1580°C to 1750°C. Under these temperatures, the cracking of the distillation residue produced during coal processing is rapidly completed. The heavy metal oxides in the slag accelerate the cracking of organic matter, dissociating the distillation residue produced during coal processing into substances such as C, H, Cl, and O. These react with oxides such as FeO, MnO, and CaO in the slag, achieving the harmless conversion of the distillation residue produced during coal processing, including harmful substances such as dioxins. 2. Add the refined (steamed) distillation residue produced during coal processing to the converter. The heavy metal oxides in the refined (steamed) distillation residue produced during coal processing can react with the C / H released by the coal processing to form liquid metal droplets, which settle into the molten steel and become a component of the steel. The thermodynamic data of the carbothermal reduction reaction of the main heavy metal elements are as follows: C+(NiO)=CO(g)+[Ni] ΔG=87660-197.93TJ / mol 3C+(Cr2O3)=2[Cr]+3CO ΔG=785128-522.79TJ / mol 5C+(V2O5)=2[V]+5CO ΔG=352528.56-300.02TJ / mol MnO+C=Mn+CO ΔG=287400-170.08TJ / mol 5C+(Nb2O5)=2[Nb]+5CO ΔG=329426-283.15TJ / mol Cu2O+C=2[Cu]+CO ΔG=80690-212.38TJ / mol 3C+MoO3=[Mo]+3CO ΔG=281100-359.49TJ / mol 3. The use of cold-solidified pellets in the converter can balance the chemical heat of converter steelmaking. The main reason is that the FeO in the cold-solidified pellets undergoes a reduction reaction with the C in the molten iron. This reaction is an endothermic reaction. The oxidation reaction of carbon is as follows: 2C+O2=2CO ΔH =-11639 KJ / kg C+O2=CO2 ΔH = -34834 KJ / kg The reduction reaction of iron oxide under steelmaking conditions is as follows: FeO+C=Fe+CO ΔH =238229 KJ / kg Fe2O3+3C=2Fe ) +3CO (g) ΔH =722432 KJ / kg Based on the above situation, the inventors used the refined (steamed) distillation residue generated in the coal processing process to mix with iron oxide and steel slag powder and press them into balls to produce cold-solidified pellets, which were used as slagging agents and steel materials in the converter steelmaking process. The chemical heat balance provided by the refined (steamed) distillation residue was used to maintain the heat balance of the converter steelmaking when the amount of cold-solidified pellets added was too large, and at the same time, the resource utilization of the refined (steamed) distillation residue generated in the coal processing process was realized.

[0011] The innovative points of the present invention are as follows: 1. Based on the above situation, the inventor proposed a process technology for using the refined (steamed) distillation residue generated in the coal processing process as a binder and a heat-generating agent, and producing cold-solidified pellets with steel slag fine powder and iron oxide scale. It can be used as a slag-removing agent and steel material for converter steelmaking, which can increase the amount of cold-solidified pellets used in converter steelmaking, and achieve the process purpose of resource utilization of the refined (steamed) distillation residue generated in the coal processing process in converter steelmaking; 2. In order to use the refined (steamed) distillation residue generated in the coal processing process as a binder and a heat-generating agent to produce cold-solidified pellets, the inventor found that the organic matter in the refined (steamed) distillation residue generated in the coal processing process is weakly acidic, and the steel slag fine powder is adhered with high-alkalinity steel slag, which can react with the refined (steamed) distillation residue generated in the coal processing process, stabilize the processing performance of the refined (steamed) distillation residue generated in the coal processing process, solve the pollution problem in the production and processing of cold-solidified pellets, and the converter can increase the amount of such cold-solidified pellets added, which is beneficial to reducing the cost and increasing the efficiency of the converter.

[0012] The beneficial effects of the present invention are as follows: 1. By utilizing the present invention, a large amount of refined (steamed) distillation residues produced by coal chemical enterprises can be utilized as a heat-generating agent for converter steelmaking, thereby solving the problem of resource utilization of refined (steamed) distillation residues produced by coal chemical enterprises; 2. The present invention utilizes the oxidation and heat release characteristics of refined (steamed) distillation residues produced by coal chemical enterprises in the steelmaking process, and uses it as a heat-generating agent, which can increase the use of cold-solidified pellets in the converter steelmaking process, and improve the amount of steel slag fines and iron oxide scale utilized by the converter, which is beneficial to cost reduction and efficiency improvement of steel enterprises; 3. China's annual steelmaking capacity is about 1 billion tons. By utilizing the process of this project, China's steelmaking enterprises can consume more than 10 million tons of refined (steamed) distillation residues produced by coal chemical enterprises each year, with significant environmental benefits. DETAILED DESCRIPTION

[0013] The embodiment of the present invention is described by taking a 180-ton converter wire rod production line as an example, and the distillation residue produced by the coal chemical enterprise involved is also applicable to distillation residue.

[0014] A method for using distillation residue as a heat-generating agent in converter steelmaking is implemented according to the following steps: S1. First, the distillation residue produced by a coal chemical enterprise is transported to the dry powder pelletizing production line for use; S2, transporting the steel slag powder and iron oxide scale to the dry powder pelletizing production line for use; S3, mixing the distillation residue with steel slag powder and iron oxide scale in a ratio of 40%:40%:20% by mass, and pressing them into 30-50 mm pellets using a high-pressure dry powder pelletizing machine; wherein the carbon content of the pellets is greater than 20%, and TFe>40%, and then transporting them to the converter production line for use; S4. During the converter smelting process, the pellets in step S3 are added to the converter as cold-solidified pellets in the early and middle stages of smelting. The adding process is consistent with the traditional process, and the added amount is increased by 15% compared with the amount of traditional cold-solidified pellets. The rest of the smelting process remains unchanged.

Claims

1. A method for using distillation residue as a heat-generating agent in converter steelmaking, characterized in that Follow these steps to implement: S1. First, the distillation residue produced by a coal chemical enterprise is transported to the dry powder pelletizing production line for use; S2, transporting the steel slag powder and iron oxide scale to the dry powder pelletizing production line for use; S3, mixing the distillation residue with steel slag powder and iron oxide scale in a ratio of 40%:40%:20% by mass, and pressing them into 30-50 mm pellets using a high-pressure dry powder pelletizing machine; wherein the carbon content of the pellets is greater than 20%, and TFe>40%, and then transporting them to the converter production line for use; S4. During the converter smelting process, the pellets in step S3 are added to the converter as cold-solidified pellets in the early and middle stages of smelting. The adding process is consistent with the traditional process, and the added amount is increased by 15% compared with the amount of traditional cold-solidified pellets. The rest of the smelting process remains unchanged.