Resource utilization method of flue gas dedusting ash in aluminum industrial production

Abstract

The invention discloses a resource utilization method of flue gas dedusting ash in aluminum industrial production, which combines the characteristics of a desulfurization process in a steel-making process, utilizes the flue gas dedusting ash generated in the aluminum industrial production process as a main raw material, adds part of active substances, and utilizes the flue gas dedusting ash generated in the aluminum industrial production process as the main raw material. The flue gas dedusting ash produced in the production process of the aluminum industry is recycled, a desulfurizing agent produced in the steel-making process is recycled, the desulfurization process of steel-making is optimized, resource utilization of the flue gas dedusting ash produced in the production process of the aluminum industry is achieved, and a new method is developed for large-scale treatment of hazardous waste produced in the aluminum industry in the steel industry in China. And the technical advantage of cross innovation in different technical fields is manifested.

Description

Technical Field

[0001] The invention relates to a resource utilization method of flue gas dust removal ash in aluminum industrial production. Background Art

[0002] Aluminum industry production includes three major process technologies: electrolytic aluminum production, aluminum recycling production and aluminum liquid refining.

[0003] During the electrolytic aluminum production process, electrolysis is a simultaneous process involving electrolysis and metallurgical reduction reactions. During this process, after the electrolyte in the electrolytic cell dissociates, sodium and potassium salts, various alkali metals, and fluorine react with carbon (and also with aluminum metal), reducing them to metal vapor (or gaseous compounds), which escapes the molten pool and enters the dust collection system. In the dust collection system, the alkali metals are secondary oxidized by oxygen in the ambient air to form alkali metal oxides, which are present in the flue gas dust. Furthermore, during the electrolysis process, fine particles of raw material in the electrolytic cell, influenced by the kinetic conditions of the electrolysis process, also enter the dust collection system and become part of the flue gas dust. Therefore, the flue gas dust generated during the electrolytic aluminum process is rich in fluorides, carbides, nitrides, alkali metal oxides, and high-temperature α-Al2O3, and is toxic and reactive.

[0004] In the process of recycled aluminum and aluminum material processing, the dust ash produced during the remelting, refining, alloying of scrap aluminum and aluminum ingots, and the thermal processing of aluminum ash to recover metallic aluminum has the following characteristics: 1. In the process of gas heating or electric heating, the grease and organic matter adhering to the recycled aluminum raw materials evaporate under high temperature conditions and enter the flue gas dust removal system, so that the flue gas dust removal ash contains some organic matter or carbide; 2. In the above production process, the added slagging agents, refining agents and other refined raw materials, and some fine-particle raw materials enter the dust removal system under the action of different kinetic conditions and become part of the dust removal ash; 3. When the aluminum liquid comes into contact with air or gas, it will also undergo oxidation reaction or chemical reaction, and some of the fine-particle reaction products produced by the violent chemical reaction will also enter the flue gas dust removal system.

[0005] Therefore, in the process of recycled aluminum and aluminum material processing, the dust ash generated during the process of remelting, refining, alloying of scrap aluminum and aluminum ingots, and thermal processing of aluminum ash to recover metallic aluminum has complex components, including fluorides, carbides, nitrides and other components, and is also reactive and toxic.

[0006] In summary, dust collected by dust collection (removal) devices for the treatment of flue gas from aluminum ash heat recovery processes, as well as dust collected by dust collection (removal) devices for the treatment of flue gas from aluminum smelting and regeneration processes (including: recycled aluminum smelting flue gas, aluminum melt purification, impurity removal, alloying, and casting flue gas), is listed in the National Hazardous Waste Catalogue (2025 Edition) as waste code 321-034-48, and is considered a toxic and reactive hazardous waste. The inventors tested two types of flue gas dust removal ash generated by aluminum industrial production processes and transported by a hazardous waste enterprise in Shanxi. The composition ranges tested are shown in Table 1 below: ; Literature review (1) Guo Jing published a paper titled "Current Status of Recycling and Utilization of Aluminum Ash and Aluminum Slag from Aluminum Electrolysis" in the 27th volume of the Journal of Materials Guide in 2013. The paper states that "This paper summarizes the sources of aluminum ash and aluminum slag at home and abroad, the recovery of valuable components such as aluminum and alumina, and the use of aluminum ash and aluminum slag to obtain new products. It is believed that the recycling of aluminum ash and aluminum slag has entered a mature stage of product development. During this period, different processes and recycling methods have emerged continuously, and the product benefits are also good. Therefore, for aluminum industry manufacturers, they should strengthen their environmental awareness, recycle aluminum ash and aluminum slag, and at the same time obtain additional products to create benefits for the enterprise." The paper did not mention the relevant content of the resource utilization of flue gas dust removal ash generated in the production process of the aluminum industry; (2) Ke Jingjing published a paper titled "Comprehensive Utilization of Aluminum Ash in Aluminum Electrolysis Process" in the 3rd issue of the Journal of Aluminum and Magnesium Communications in 2011. The paper states that "With the rapid development of the aluminum smelting industry in recent years, aluminum ash has increased significantly. Through the unremitting efforts of scientific research and production workers over the years, Aluminum ash has been widely used. However, it must also be admitted that there is still a lot of work to be done on how to make better use of aluminum ash and turn it into treasure. With the continuous deepening of research, the application scope and availability of aluminum ash will surely become larger and larger." The article also did not mention the treatment process of flue gas dust removal ash generated by the aluminum industry; (3) Wang Weijing published a paper entitled "Progress in Resource Utilization and Harmless Treatment of Titanium and Aluminum Hazardous Wastes" in the third issue of "Mineral Protection and Utilization" in 2019. The article states that "In view of the potential risks of serious environmental pollution caused by titanium and aluminum hazardous wastes in my country and the waste of valuable element resources. Taking the acid decomposition waste slag generated by the sulfuric acid method titanium dioxide industry and the aluminum ash generated by the aluminum smelting process as typical representatives, the main progress and achievements made in the resource utilization and harmless treatment of titanium and aluminum hazardous wastes at home and abroad in recent years are reviewed. The main conclusions are as follows: (1) Cyclone separation and magnetic separation are the two most widely used methods for treating acid decomposition waste slag in the titanium dioxide industry. However, there are still problems such as low TiO2 recovery rate and TiO2 in the recovered products. Low grade and other problems; although the alkaline method has solved the above problems and achieved efficient recovery and utilization of titanium resources in acid hydrolysis waste slag, its current situation of poor economic efficiency and small scale needs to be further upgraded; (2) There are many studies on aluminum ash treatment, which mainly focus on resource utilization, and its harmless treatment is the fundamental means to completely solve the hazardous waste of aluminum ash. Further formulation of toxicity detection standards and environmental risk assessment of aluminum ash, strengthening the monitoring and harmless management of elements such as fluorine and nitrogen in aluminum ash, and realizing the promotion of aluminum ash resource utilization and harmless treatment technology are the future research directions. "The article also does not mention the relevant process technology content of the treatment and utilization of flue gas dust removal ash generated by the aluminum industry.

[0007] According to the above literature, the dust ash from the flue gas produced by the aluminum industry has complex composition and large fluctuations in composition. It is a hazardous waste that is difficult to treat and there is currently no clear resource utilization process.

[0008] Desulfurization is the most important process in the steelmaking process. The desulfurization process in steelmaking mainly consists of three process links: desulfurization of molten iron, desulfurization during the steelmaking and tapping process, and desulfurization during the molten steel refining process.

[0009] Sulfur is one of the active non-metallic elements and is also a surfactant in pure iron liquid and steel liquid. At the temperature of ironmaking and steelmaking, it can combine with many metal elements and non-metallic elements to form gaseous, solid or liquid compounds, making the desulfurization form more diverse.

[0010] References (1) Bao Guangda published a paper titled "Study on the Effect of CaF2 and Al2O3 on the Performance of KR Desulfurizer" in the 4th issue of "Steelmaking" magazine in 2023. The paper states: "Based on the experimental results and the influence of various factors, a desulfurizer with a melting temperature of 1400-1424℃, W(SiO2)=0-10%, W(CaF2) and W(Al2O3) of 5%-15%, and W(MgO)=6% was obtained. Its desulfurization efficiency is significantly better than the desulfurizer currently used by the enterprise, and And the comprehensive desulfurization ability of CaF2 is stronger than that of Al2O3. ", the article does not mention the use of flue gas dust generated by the aluminum industry as a desulfurizer; (2) Yang Biwen, Wang Haibei, Zheng Chaozhen, et al. published a paper entitled "The Effect of B2O3-Na2O Slag Adjuster on the Performance of Vanadium Titanium Hot Metal Desulfurization Slag" in the 10th issue of "Steel" magazine in 2021. The article states that "According to the desulfurization slag resulfurization test and melting point and viscosity analysis results, a small amount of B2O3+Na2O has a significant effect, and the industry In the industry, borax can be used as one of the main components of slag conditioning agents." The article also does not mention the process of using flue gas dust generated by the aluminum industry as a desulfurization agent; (3) Peng Qichun published a paper entitled "Research Progress on Deep Desulfurization of New LF Refining Slag" in the 3rd issue of "Steelmaking" magazine in 2010. The article states that "the currently commonly used desulfurized refining slag is mainly composed of CaO, Al2O3, SiO2, MgO, CaF2 and other components. CaO is an alkaline oxide and plays a major role in desulfurization. The article states that Al2O3 itself is acidic and has no desulfurizing effect, but it can reduce the basicity of the slag to a certain extent. However, Al2O3 can combine with CaO to form a low-melting-point compound, lowering the melting point of the refined slag. SiO2 mainly acts as a flux, also contributing to the foaming of the refined slag and reducing point-like inclusions in the steel. MgO has a certain ability to bind sulfur, but this ability is not as strong as CaO. The article also fails to mention the process of using flue gas dust generated by the aluminum industry as a desulfurizer.

[0011] In summary, there is currently no introduction to a process for using flue gas dust produced by the aluminum industry as a desulfurization agent for steelmaking. Summary of the Invention

[0012] The purpose of the present invention is to provide a method for resource utilization of flue gas dust removal ash in aluminum industrial production. Combined with the desulfurization process characteristics in the steelmaking process, the flue gas dust removal ash generated in the aluminum industrial production process is used as the main raw material, and some active substances are added. The flue gas dust removal ash generated in the aluminum industrial production process is used as the main raw material to produce a desulfurizer in the steelmaking process for resource utilization, thereby optimizing the steelmaking desulfurization process and realizing the resource utilization of the flue gas dust removal ash generated in the aluminum industrial production process.

[0013] The technical solution adopted by the present invention is a method for resource utilization of flue gas dust removal ash in aluminum industrial production, which is implemented according to the following steps: S1. First, the flue gas dust generated by the electrolytic aluminum enterprise is transported to the dry powder pelletizing production line for use; S2. Purchase coal tar as a binder and transport it to the dry powder pelletizing production line for use; S3, purchase CaCO3 particles with a particle size of less than 1mm and transport them to the pelletizing production line for use; S4. Evenly mix the flue gas dust ash and CaCO3 particles generated by the above-mentioned electrolytic aluminum enterprise in a ratio of 95%:5% by mass, then drip the above-mentioned coal tar into the mixture and stir evenly, and then use a high-pressure dry powder pelletizing machine to press into 30-50 mm pellets as a desulfurizer; wherein W[Al2O3+K2O+Na2O+Cl+F]% in the pellets is greater than 40%. If W[Al2O3+K2O+Na2O+Cl+F]% is less than 40%, reduce the amount of the flue gas dust ash, add aluminum ash to increase the amount of W[Al2O3+K2O+Na2O+Cl+F]% to greater than 40%, and then transport it to the molten iron KR desulfurization production line for use; S5. When desulfurizing molten iron, 1 kg of the pellets and 5 kg of lime are added to each ton of molten iron for desulfurization. The process used is the same as the original desulfurization process. S6. The pellets are used for desulfurization in the process of converter steel tapping. 1.5 kg of the pellets and 2.5 kg of lime are added per ton of molten steel to desulfurize the crude molten steel in the converter. The process used is consistent with the original desulfurization process.

[0014] The inventor discovered the following scientific phenomena through experiments and research: 1. Regardless of the desulfurization process, it is accompanied by chemical reactions between ions. The main components that affect steelmaking desulfurization include potassium salts and sodium salts with smaller ionic radius, fluoride ions, reducing components and aluminum oxide. When the desulfurizer contains alkali metal potassium salts and sodium salts, the potassium salts and sodium salts can not only form compounds with the sulfur element in the molten steel, but also improve the desulfurization reaction capacity of steelmaking; 2. Mineral tissues containing calcium and magnesium can react with sulfur to form stable compounds, and are one of the main components of current desulfurizers; 3. Alumina can form a stable 11CaO·7Al2O3·CaS mineral structure during the steelmaking desulfurization process, and is an important component that increases the steelmaking desulfurization reaction in the positive direction.

[0015] 4. The inventors discovered that the basic principle of desulfurization in steelmaking is to convert sulfur dissolved in molten iron into an insoluble phase, which then enters the slag or escapes into the gas phase through the slag. The generally accepted ionic equation for the desulfurization reaction between alkaline slag and molten iron is: [S]+(O 2- )=(S 2- )+[O] ΔG=71956-38T The desulfurization reaction in molten iron is a reduction process, [S]+2e - =S 2- ; Generate S 2- Then combine with appropriate metal cations. Ca 2+ With S 2- The bond is the strongest, it can be dissolved in the slag, or it can exist in the form of calcium compounds. 2- Most of the electrons are from O 2- Provided, the desulfurization process can be written as: [S]+O 2- =S 2- +[O] If O 2- is provided by calcium oxide, then the reaction formula is: [S]+CaO=CaS+[O] According to the above theory, the potassium salt, sodium salt, fluoride and magnesium-calcium-containing mineral components in the flue gas dust produced by the aluminum industry can all dissociate into anions, which are helpful for the desulfurization reaction of molten iron.

[0016] 5. The chlorides contained in the dust from the flue gas produced by the aluminum industry can produce the following chemical reactions: NaCl→Na + +Cl - Na + +[O] 2- →Na2O 2Cl - +MgO→MgCl2+O 2- 2Cl - +CaO→CaCl2+O 2- The minerals formed in the middle of the slag include CaClF, Ca3OCl4, etc. Therefore, chloride is an important substance in the metallurgical process that can lower the melting point of the slag and help desulfurize and dephosphorize the molten iron.

[0017] 6. The inventors discovered that the dust from the flue gas produced by the aluminum industry has small particle size, is formed during a high temperature process, has a distorted crystal structure, requires less chemical heat to participate in the desulfurization reaction, and can increase the speed of the desulfurization reaction.

[0018] The innovative features of the present invention are as follows: 1. Based on the above scientific discoveries, the inventors have proposed a process technology that uses flue gas dust generated during aluminum production as the main raw material for steelmaking desulfurization, adding some active substances to it as a steelmaking desulfurization agent. This process technology can be used in the process of steelmaking desulfurization and molten iron desulfurization, achieving the process goal of resource utilization of flue gas dust generated during aluminum production; 2. Since the composition of dust ash generated during aluminum industrial production fluctuates greatly, the inventors have utilized the basic principles of desulfurization reaction. While ensuring that the main components meet the desulfurization process requirements, the desulfurizer produced can use different aluminum industrial flue gas dust ash to meet the process requirements of steelmaking desulfurization, that is, W (Al2O3+ K2O+Na2O+Cl+F)>40%. When the above components cannot reach 40%, aluminum ash can be added to supplement Al2O3; 3. To achieve the above process objectives, the inventors used waste coal tar as a binder, took advantage of the fact that oil can form oil salts with alkali metal compounds, and adopted high-pressure dry powder anhydrous pelletizing technology to process the dust generated in the aluminum industry production process into a product that can meet the process requirements of steelmaking desulfurization agents, thereby achieving the process objective of efficient resource utilization of flue gas dust generated in the aluminum industry production process; 4. To increase the reaction speed of the desulfurizer, the inventors added some CaCO3 (of which CaO>50%) during the pelletizing process as a accelerator to increase the desulfurization reaction interface. The CO2 gas released by the thermal decomposition of CaCO3 caused the desulfurizer pellets to break into N particles, thereby increasing the desulfurization reaction speed and efficiency. 5. Coal tar, as a binder, can act as a reducing agent in the desulfurization process to participate in the desulfurization reaction and increase the speed of the desulfurization reaction.

[0019] The beneficial effects of the present invention are as follows: 1. By utilizing the present invention, the flue gas dust removal ash generated in the aluminum industry production process can be utilized on a large scale, solving the problem of resource utilization of the flue gas dust removal ash generated in the aluminum industry production process; 2. The present invention utilizes the characteristics of desulfurization of different components and adopts the advantages of superposition of the desulfurization effects of different components of the flue gas dust removal ash generated in the aluminum industry production process, which can improve the efficiency of the steelmaking desulfurization reaction; 3. By utilizing the process of the present invention, the process problem of the difficult treatment of the flue gas dust removal ash generated in the aluminum industry production process is solved, and at the same time, the amount of special desulfurization flux used in steelmaking desulfurization is reduced, which has huge environmental benefits. DETAILED DESCRIPTION

[0020] The embodiment of the present invention is described by taking a 150-ton converter plate production line as an example, wherein desulfurization is mainly used in the KR desulfurization process of the production line and the desulfurization process during the converter tapping process.

[0021] A method for resource utilization of flue gas dust in aluminum industry production is implemented according to the following steps: S1. First, the flue gas dust generated by the electrolytic aluminum enterprise is transported to the dry powder pelletizing production line for use; S2. Purchase coal tar as a binder and transport it to the dry powder pelletizing production line for use; S3, purchase CaCO3 particles with a particle size of less than 1mm and transport them to the pelletizing production line for use; S4. The flue gas dust ash generated by the electrolytic aluminum enterprise and the CaCO3 particles are mixed uniformly in a ratio of 95% by mass:5% by mass to form a mixture, and then 5% by weight of coal tar is dripped into the mixture, and after stirring evenly, the mixture is pressed into 30-50 mm pellets using a high-pressure dry powder pelletizing machine as a desulfurizer; wherein the W[Al2O3+K2O+Na2O+Cl+F]% in the pellets is greater than 40%. If the W[Al2O3+K2O+Na2O+Cl+F]% is less than 40%, the amount of the flue gas dust ash is reduced, and aluminum ash is added to increase the W[Al2O3+K2O+Na2O+Cl+F]% to greater than 40%, and then the pellets are transported to the molten iron KR desulfurization production line for use; S5. When desulfurizing molten iron, 1 kg of the pellets and 5 kg of lime are added to each ton of molten iron for desulfurization. The process used is the same as the original desulfurization process. S6. The pellets are used for desulfurization in the process of converter steel tapping. 1.5 kg of the pellets and 2.5 kg of lime are added per ton of molten steel to desulfurize the crude molten steel in the converter. The process used is consistent with the original desulfurization process.

Claims

1. A method for resource utilization of flue gas dust in aluminum industry production, characterized in that Follow these steps to implement production: S1. First, the flue gas dust generated by the electrolytic aluminum enterprise is transported to the dry powder pelletizing production line for use; S2. Purchase coal tar as a binder and transport it to the dry powder pelletizing production line for use; S3, purchase CaCO3 particles with a particle size of less than 1mm and transport them to the pelletizing production line for use; S4. The flue gas dust ash generated by the electrolytic aluminum enterprise and the CaCO3 particles are mixed uniformly in a ratio of 95% by mass:5% by mass to form a mixture, and then 5% by weight of coal tar is dripped into the mixture, and after stirring evenly, the mixture is pressed into 30-50 mm pellets using a high-pressure dry powder pelletizing machine as a desulfurizer; wherein the W[Al2O3+K2O+Na2O+Cl+F]% in the pellets is greater than 40%. If the W[Al2O3+K2O+Na2O+Cl+F]% is less than 40%, the amount of the flue gas dust ash is reduced, and aluminum ash is added to increase the W[Al2O3+K2O+Na2O+Cl+F]% to greater than 40%, and then the pellets are transported to the molten iron KR desulfurization production line for use; S5. When desulfurizing molten iron, 1 kg of the pellets and 5 kg of lime are added to each ton of molten iron for desulfurization. The process used is the same as the original desulfurization process. S6. The pellets are used for desulfurization in the process of converter steel tapping. 1.5 kg of the pellets and 2.5 kg of lime are added per ton of molten steel to desulfurize the crude molten steel in the converter. The process used is consistent with the original desulfurization process.