Method for converting steel with rectification residues as a heating agent

Abstract

The application discloses a method for using rectification residues as a heating agent in converter steelmaking, and is aimed at the composition characteristics of the rectification residues generated in the coal processing process, and combines the process technology of applying cold solid pellets in the converter production, so that the rectification residues generated in the coal processing process are used as the binding agent and the heating agent, and are combined with the steel slag fine powder and the oxidized iron scale as the main raw materials to form the pellets, and then are used as the cold solid pellet resource utilization in the converter steelmaking process, the chemical heat provided by the rectification residues generated in the coal processing process in the converter oxidation process is used to balance the chemical heat required by the reduction reaction of the cold solid pellets, and the process of the converter steelmaking is optimized.

Description

Technical Field

[0001] This invention relates to a method for using distillation residue as a heating agent in converter steelmaking. Background Technology

[0002] The distillation process of coal processing generates various residues containing different types of organic matter and trace amounts of heavy metals, posing potential hazards to the environment and humans. These residues are included in the National Hazardous Waste Catalogue. The list of hazardous wastes generated during coal processing in the 2025 National Hazardous Waste Catalogue is shown in the table below: ; The main harmful substances in the distillation residues produced during coal processing include: polycyclic aromatic hydrocarbons, acetophenone, styrene dimers, phenol and cumylphenol, alkenylbenzene, alcohols, and compounds containing heavy metals such as Cr, Ni, and Cu.

[0003] A review of literature (1) Qiu Zegang, Li Zhuangzhuang, and Li Zhiqin published a paper entitled "Research Progress on Medium and Low Temperature Coal Tar Conversion and Utilization Technology" in the 4th issue of the Journal of Petroleum Science 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. This paper introduces the current research status of medium and low temperature coal tar utilization at home and abroad, and reviews and analyzes the research and development of medium and low temperature coal tar separation, hydrogenation and upgrading utilization, production of fuel oil, special oil products and high-value chemicals, coal tar blending and hydrogenation, and coal pitch utilization. Based on the composition characteristics of medium and low temperature coal tar fractions, a technical route of "graded and fractional conversion and utilization" of medium and low temperature coal tar is proposed, making full use of its molecular characteristic structure, and studying efficient catalysts to make coal tar Targeted conversion into target products. This provides a diversified, high-value and refined approach for the efficient and clean utilization of coal tar. The content of the article does not mention the relevant content of the resource utilization of the distillation residue generated 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 Saturation Reaction of Polycyclic Aromatic Hydrocarbons in Oil-Rich Coal Tar" in the 7th issue of the 2024 Coalfield Geology and Exploration magazine. The article states that "coal tar is a liquid product of low-temperature pyrolysis and high-temperature coking processes in 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 for hydrogenating to produce liquid fuels. Common coal tar hydrogenation to fuel oil process technologies include fraction hydrogenation, delayed coking hydrogenation, full-fraction hydrogenation, wide-fraction hydrogenation, slurry bed hydrogenation, and fluidized bed hydrogenation. By selecting appropriate process technologies, hydrogenation of 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 distillation residue generated during coal processing in the steelmaking industry; (3) Hui Jun, Sun Haocheng, Chen Junyu, Liu Chunyang, the four authors, in the first issue of 2023 A paper titled "Research Progress on Resource Utilization of Phenol Tar" was published in the journal *Modern Chemical Industry*. The paper states that "Phenol tar is a common hazardous waste generated in phenol / ketone production plants, produced in large quantities with complex composition. Blending and outsourcing are traditional disposal methods for enterprises, while research on recycling is relatively limited. This paper reviews the research progress on resource utilization of phenol tar in recent years from two aspects: co-utilization in the plant and extraction of high-value components. Currently, the main utilization methods of phenol tar are as a partial feedstock for heavy oil processing plants and continuous distillation to recover organic monomers; other methods lack in-depth research." The paper also makes no mention of the resource utilization of distillation residues generated during coal processing in the steelmaking industry.

[0004] As can be seen from the literature above, the distillation residue produced during coal processing has a complex composition and fluctuates greatly, making it a hazardous waste that is difficult to handle.

[0005] Steelmaking and rolling processes in steel enterprises generate a certain amount of iron-containing dust and sludge, with the two largest contributors being iron oxide scale and steel slag powder. The mature technology of using dry powder pelletizing at room temperature to pelletize iron oxide scale and steel slag powder for use as raw materials in converter steelmaking is known in the industry as cold pelletizing technology.

[0006] The main function of using chilled pellets in converter steelmaking is to recover iron-containing materials and to utilize the iron oxide in the pellets for slag formation and to balance the chemical heat of converter steelmaking. Currently, the amount of chilled pellets used per ton of steel in converter steelmaking is less than 50 kg. The main reason for this limited use is that the iron oxide in the chilled pellets absorbs a large amount of chemical heat during the reduction process, affecting the temperature control of converter steelmaking.

[0007] According to literature (1), Zhang Qingxue published a paper entitled "Application Research of Medium-Temperature Solidified Pelletizing of Converter Dust and Sludge" in the 10th issue of "Iron and Steel" magazine in 2005. The paper states: "In order to understand the smelting performance of medium-temperature solidified pelletizing of converter dust and sludge in converter, a production test was conducted. During the test, the composition of molten iron, the carbon, phosphorus, and sulfur content of molten steel at the end point, and slag data were collected under normal production and test conditions. The data were compared and regressed to analyze the desulfurization and dephosphorization capacity, slag formation time, oxygen supply capacity, and iron element recovery under normal production and test conditions. The test showed that: the application of dust and sludge pellets as a slag-forming agent can accelerate the formation of initial slag, improve the desulfurization and dephosphorization capacity of converter slag, and provide a certain amount of oxygen." The article states that the content of "recovering some iron elements" is not mentioned in the article. The article does not mention the content of utilizing the distillation residue generated during the coal processing process in the converter steelmaking resource utilization process. (2) Li Weidong, Sun Qun, Wang Xianghui, Ding Yong, and Wang Guoqing published a paper entitled "Application of iron-carbon composite pellets in converter steelmaking" in the third issue of Ansteel Technology magazine in 2011. The article states that "in order to realize the application of iron-carbon composite pellets in converter steelmaking, the influence 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 slag-forming agents or cooling agents, which can stabilize the sulfur recovery of the converter. When iron-carbon composite pellets are used as slag-forming agents, they can shorten the slag formation time, improve the phosphorus removal 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 utilizing the distillation residue generated during the coal processing process in the converter steelmaking resource utilization process. In summary, there is currently no technological method for utilizing the distillation residue generated during coal processing in converter steelmaking. Summary of the Invention

[0008] The purpose of this invention is to provide a method for using distillation residue as a heating agent in converter steelmaking. This method can make extensive use of the distillation residue generated by coal chemical enterprises as a heating agent in converter steelmaking, thus solving the problem of resource utilization of distillation residue generated by coal chemical enterprises.

[0009] A method for using distillation residue as a heating agent in converter steelmaking is carried out according to the following steps: S1. First, the distillation residue generated by the coal chemical enterprise is transported to the dry powder pelletizing production line for later use. S2. Transport the steel slag concentrate and iron oxide scale to the dry powder pelletizing production line for later use; S3. Mix the distillation residue with steel slag concentrate and iron oxide scale in a mass percentage ratio of 40%:40%:20%, and press it into pellets of 30-50mm using a high-pressure dry powder pelletizer. The carbon content of the pellets is greater than 20%, and TFe is greater than 40%. Then, transport them to the converter production line for later use. S4. During the converter smelting process, the pellets from step S3 are added to the converter as cold-solidified pellets in the early and middle stages of smelting. The addition process is the same as the traditional process, but the amount added is 15% more than that of the traditional cold-solidified pellets. The rest of the smelting process remains unchanged.

[0010] The inventors discovered the following scientific phenomena through experimentation and research: 1. At the end of the converter blowing process, the temperature of the molten steel and the temperature of the slag in the converter are the highest in the converter steelmaking process, ranging from 1580℃ to 1750℃. Under these temperature conditions, the cracking of the distillation residues produced during coal processing is completed rapidly. The heavy metal oxides in the slag have the function of accelerating the cracking of organic matter, dissociating the distillation residues produced during coal processing into substances such as C, H, Cl, and O. These substances can react with oxides such as FeO, MnO, and CaO in the slag, thus achieving the harmless transformation of the distillation residues produced during coal processing, including harmful substances such as dioxins. 2. The distillation residue produced during coal processing is added to the converter. The heavy metal oxides in the distillation residue can react with the C / H released from its own decomposition, becoming liquid metal droplets that settle into the molten steel and become a component of the steel product. The thermodynamic data of the carbothermic reduction reaction of the main heavy metal elements are as follows: C+(NiO)=CO(g)+[Ni] ΔG = 87660 - 197.93 TJ / mol 3C + (Cr₂O₃) = 2[Cr] + 3CO ΔG = 785128 - 522.79 TJ / mol 5C + (V₂O₅) = 2[V] + 5CO ΔG = 352528.56 - 300.02 TJ / mol MnO + C = Mn + CO ΔG = 287400 - 170.08 TJ / mol 5C + (Nb₂O₅) = 2[Nb] + 5CO ΔG = 329426 - 283.15 TJ / mol Cu₂O + C = 2[Cu] + CO ΔG = 80690 - 212.38 TJ / mol 3C + MoO3 = [Mo] + 3CO ΔG = 281100 - 359.49 TJ / mol 3. The use of chilled pellets in converters can balance the chemical heat of converter steelmaking, mainly because the FeO in the chilled pellets undergoes a reduction reaction with the C in the molten iron. This reaction is endothermic. The oxidation reaction of carbon is as follows: 2C + O2 = 2CO ΔH =-11639 KJ / kg C + O₂ = CO₂ ΔH = -34834 KJ / kg The reduction reactions of iron oxides under steelmaking conditions are as follows: FeO + C = Fe + CO ΔH = 238229 KJ / kg Fe₂O₃ + 3C = 2Fe ) +3CO (g) ΔH = 722432 KJ / kg Based on the above scientific findings, the inventors utilize the distillation residue generated during coal processing to mix with iron oxide and steel slag concentrate, press it into pellets, and then produce cold-solidified pellets. These pellets are used as slag-reducing agents and steel feedstocks during converter steelmaking. The chemical heat balance provided by the distillation residue is utilized to balance the heat balance of converter steelmaking when the amount of cold-solidified pellets added is too large. At the same time, the resource utilization of the distillation residue generated during coal processing is realized.

[0011] The innovations of this invention are as follows: 1. Based on the above scientific discoveries, the inventors proposed a process technology that uses the distillation residue generated during coal processing as a binder and heating agent to produce cold-solidified pellets with steel slag concentrate and iron oxide scale. This process can be used as a slag-reducing agent and steel material in converter steelmaking, increasing the amount of cold-solidified pellets used in converter steelmaking and achieving the technological objective of resource utilization of the distillation residue generated during coal processing in converter steelmaking. 2. In order to use the distillation residue generated during coal processing as a binder and heating agent to produce cold-solidified pellets, the inventors discovered that the organic matter in the distillation residue generated during coal processing is weakly acidic, and the steel slag concentrate is adhered to with high-alkalinity steel slag. This allows the residue to react with the distillation residue generated during coal processing, stabilizing its processing performance, solving the pollution problem in the production and processing of cold-solidified pellets, and increasing the amount of these cold-solidified pellets added to the converter, which is beneficial for cost reduction and efficiency improvement in the converter.

[0012] The beneficial effects of this invention are as follows: 1. This invention enables the large-scale utilization of distillation residues generated by coal chemical enterprises as a heating agent in converter steelmaking, solving the problem of resource utilization of distillation residues generated by coal chemical enterprises; 2. This invention utilizes the exothermic oxidation characteristics of distillation residues generated by coal chemical enterprises in the steelmaking process as a heating agent, which can increase the amount of cold-solidified pellets used in converter steelmaking, and increase the amount of steel slag concentrate and iron oxide scale utilized in the converter, which is conducive to cost reduction and efficiency improvement for steel enterprises; 3. China's annual steelmaking capacity is about 1 billion tons. Using the process of this project, Chinese steelmaking enterprises can consume more than 10 million tons of distillation residues generated by coal chemical enterprises every year, with significant environmental benefits. Detailed Implementation

[0013] The embodiments of the present invention are illustrated using a 180-ton converter wire rod production line as an example. The distillation residues produced by coal chemical enterprises involved are also applicable to distillation residues.

[0014] A method for using distillation residue as a heating agent in converter steelmaking is carried out according to the following steps: S1. First, the distillation residue generated by the coal chemical enterprise is transported to the dry powder pelletizing production line for later use. S2. Transport the steel slag concentrate and iron oxide scale to the dry powder pelletizing production line for later use; S3. Mix the distillation residue with steel slag concentrate and iron oxide scale in a mass percentage ratio of 40%:40%:20%, and press it into pellets of 30-50mm using a high-pressure dry powder pelletizer. The carbon content of the pellets is greater than 20%, and TFe is greater than 40%. Then, transport them to the converter production line for later use. S4. During the converter smelting process, the pellets from step S3 are added to the converter as cold-solidified pellets in the early and middle stages of smelting. The addition process is the same as the traditional process, but the amount added is 15% more than that of the traditional cold-solidified pellets. The rest of the smelting process remains unchanged.

Claims

1. A method for using distillation residue as a heating agent in converter steelmaking, characterized in that... Follow these steps: S1. First, the distillation residue generated by the coal chemical enterprise is transported to the dry powder pelletizing production line for later use. S2. Transport the steel slag concentrate and iron oxide scale to the dry powder pelletizing production line for later use; S3. Mix the distillation residue with steel slag concentrate and iron oxide scale in a mass percentage ratio of 40%:40%:20%, and press it into pellets of 30-50mm using a high-pressure dry powder pelletizer. The carbon content of the pellets is greater than 20%, and TFe is greater than 40%. Then, transport them to the converter production line for later use. S4. During the converter smelting process, the pellets from step S3 are added to the converter as cold-solidified pellets in the early and middle stages of smelting. The addition process is the same as the traditional process, but the amount added is 15% more than that of the traditional cold-solidified pellets. The rest of the smelting process remains unchanged.