A method for hydrogen-rich coupled smelting of high-proportion pellets in a blast furnace
By optimizing the pellet feed ratio and hydrogen-rich coupled smelting method, the problems of decreased permeability and increased carbon emissions caused by increasing the proportion of pellets in blast furnace ironmaking were solved, achieving efficient and stable low-carbon smelting results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHOUGANG GROUP CO LTD
- Filing Date
- 2026-03-10
- Publication Date
- 2026-06-02
Smart Images
Figure CN122128481A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of metallurgical ironmaking technology, and in particular to a method for hydrogen-rich coupled smelting of high-proportion pellets in a blast furnace. Background Technology
[0002] The steel industry is a crucial foundation of the national economy and a major contributor to energy consumption and carbon emissions. Statistics show that the steel industry accounts for approximately 15%-18% of the nation's total carbon emissions, with blast furnace ironmaking accounting for over 70% of the total emissions from the entire steelmaking process. Therefore, promoting low-carbon innovation in blast furnace ironmaking is crucial for the nation's implementation of its "dual-carbon" strategic goals. Currently, blast furnace ironmaking primarily uses sintered ore and pelletized ore as iron-containing raw materials. Among these, sintering has long dominated the blast furnace burden structure in my country due to its cost and technological inertia. However, the sintering process itself is energy-intensive and produces significant pollution; its energy consumption and carbon emissions are approximately three times that of the pelletizing process. Increasing the proportion of pelletized ore in the blast furnace feed is widely recognized as one of the most direct and effective ways to reduce carbon emissions from the ironmaking system.
[0003] However, in actual industrial production, increasing the proportion of pellets to a high level (e.g., exceeding 60%) faces severe technical challenges. The core issue lies in the significant difference between the metallurgical behavior of pellets and sinter under high-temperature reduction conditions in the furnace. As the proportion of pellets increases, the permeability of the furnace charge deteriorates in the softening zone, easily leading to an increase in the overall pressure differential of the blast furnace and unstable gas flow distribution, which can severely disrupt furnace operations. To maintain smooth operation, it is often necessary to adopt operations such as developing edge flow, which in turn leads to an increase in the fuel ratio, thus offsetting some of the carbon emission reduction benefits brought by pellets. This creates a contradictory situation of "increasing proportion - increasing pressure differential - high consumption," making it difficult to realize the environmental advantages of high-proportion pellet smelting under economically feasible conditions.
[0004] To overcome these challenges, existing technologies have proposed various solutions. The core idea mainly focuses on optimizing the top charging system. By adjusting the ore and coke charging matrix, the particle size distribution and porosity of the charge in the cold state are improved, thereby enhancing the permeability of the upper charge column. While these methods have some effect on improving furnace conditions, they fail to fundamentally address the essential problem of a sharp decrease in permeability caused by the reduction expansion, softening, and agglomeration of pellets in the lower part of the furnace after the reduction reaction. Summary of the Invention
[0005] This application provides a method for hydrogen-rich coupled smelting of high-proportion pellets in a blast furnace to solve the following technical problem: how to achieve low CO2 emissions from blast furnace ironmaking through high-proportion pellet smelting.
[0006] This application provides a method for coupled hydrogen-rich blast furnace smelting of high-proportion pellets, the method comprising:
[0007] Alkaline pellets with optimized metallurgical properties are mixed with acidic pellets and / or sinter to obtain a composite furnace charge with a high proportion of pellets. The composite charge is fed into the blast furnace for smelting. During the smelting process, hydrogen-rich gas is injected into the tuyeres of the blast furnace, and the amount of pulverized coal injected, the oxygen enrichment rate of the tuyeres, and the theoretical combustion temperature of the tuyeres are adjusted simultaneously to form a coupled smelting environment inside the blast furnace, thereby achieving stable smelting under conditions of high pellet proportion.
[0008] Optionally, the alkaline pellets satisfy the following: The alkalinity is 1.1–1.5, the reduction expansion rate is less than 13%, and the reduction adhesion index is less than 18%. The mass fraction of MgO is 0.5% to 3.0%, and the mass fraction of SiO2 is 2.5% to 6.0%.
[0009] Optionally, the total mass of the pellets is 65% to 100% of the mass of the composite furnace charge, and the basicity of the composite furnace charge is 1.45 to 1.60.
[0010] Optionally, the slag obtained after smelting has the following properties: basicity of 1.1 to 1.2 and mass ratio of MgO to Al2O3 of 0.50 to 0.60.
[0011] Optionally, the composite furnace charge may also include one or more of lump ore, direct reduced iron, pre-reduced pellets, scrap steel, and cold-pressed briquettes.
[0012] Optionally, the feeding operation may also include adding fuel and flux to the composite charge.
[0013] Optionally, the injection rate of the hydrogen-rich gas is 10 Nm³. 3 / t iron ~ 300Nm 3 / t iron, wherein the pulverized coal injection rate is 200kg / t iron to 300kg / t iron.
[0014] Optionally, the oxygen enrichment rate of the air vent is 4% to 8%, and the theoretical combustion temperature of the air vent area is 2000℃ to 2200℃.
[0015] Optionally, the hydrogen-rich gas is at least one of coke oven gas, hydrogen, natural gas, syngas, and hydrogen-containing gases.
[0016] Optionally, the volume fraction of hydrogen in the hydrogen-containing gas is greater than 40%.
[0017] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a method for coupled smelting of high-proportion pellets with hydrogen in a blast furnace. The method includes: mixing alkaline pellets with optimized metallurgical properties with acidic pellets and / or sinter to obtain a composite charge with a high proportion of pellets; charging the composite charge into the blast furnace for smelting; and during the smelting process, injecting hydrogen-rich gas into the tuyeres of the blast furnace and simultaneously adjusting the pulverized coal injection rate, tuyer oxygen enrichment rate, and theoretical combustion temperature of the tuyeres to form a coupled smelting environment inside the blast furnace, thereby achieving stable smelting under high pellet proportion conditions. By increasing the basicity of alkaline pellets to 1.1–1.5 and strictly controlling their reduction expansion rate and reduction bonding index, while simultaneously adjusting the MgO and SiO2 content, a metallurgically optimized alkaline pellet is obtained. This directly improves the structural stability of the pellets in the high-temperature zone of the furnace, reduces the inherent risk of permeability degradation due to excessive expansion, pulverization, and agglomeration, and makes it possible to use pellets as the main raw material. During the batching and mixing stage, not only is the total proportion of pellets controlled, but calculations and adjustments are also made to maintain the basicity of the entire composite furnace charge within a specific range of 1.45–1.60. This aims to ensure that even with a high proportion of pellets, the final slag still possesses excellent fluidity, desulfurization, and alkali removal capabilities, chemically guaranteeing the smooth slag-iron reaction in the lower part of the blast furnace. During the blast furnace smelting process, hydrogen-rich gas is injected into the tuyeres, and the pulverized coal injection rate, oxygen enrichment rate, and theoretical combustion temperature are simultaneously and precisely adjusted. Hydrogen, as a highly efficient reducing agent, directly replaces part of the carbon reduction, reducing carbon emissions. Simultaneously, the small molecular size and rapid diffusion of hydrogen, along with its reduction product being water vapor, help improve the utilization efficiency of in-furnace gas and dilute its viscosity, thereby directly improving the permeability of the burden and precisely offsetting the risk of increased pressure differential caused by high-proportion blast furnace pellets. Through oxygen enrichment and coal quantity adjustment, the changes in theoretical combustion temperature and heat caused by the injection of hydrogen-rich gas are compensated, stabilizing the thermal state of the tuyeres area within the optimal window. This provides stable thermal support for the melting of the upper burden and the reaction of the lower slag and iron, forming a chemical-thermodynamic complementarity with hydrogen-rich reduction. This application organically combines the low-carbon emission potential of high-proportion blast furnace pellets with the low-carbon emission driving force of hydrogen-rich smelting, and completely eliminates the high pressure differential resistance of high-proportion blast furnace pelletizing. Ultimately, under industrially feasible stable blast furnace operating conditions, it simultaneously achieves the two major goals of improved permeability and reduced carbon emissions. Attached Figure Description
[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.
[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic flow diagram of a high-proportion hydrogen-rich coupled smelting method for blast furnace pellets provided in an embodiment of this application. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0022] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "including" and "contains" as used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.
[0023] Figure 1 This is a schematic flow diagram of a high-proportion hydrogen-rich coupled smelting method for blast furnace pellets provided in an embodiment of this application.
[0024] like Figure 1 As shown in the embodiment of this application, a method for hydrogen-rich coupled smelting of high-proportion pellets in a blast furnace is provided, the method comprising: S1. Alkaline pellets with optimized metallurgical properties are mixed with acidic pellets and / or sinter to obtain a composite furnace charge with a high proportion of pellets. S2. Perform a charging operation on the composite furnace charge to load the composite furnace charge into the blast furnace for smelting; S3. During the smelting process, hydrogen-rich gas is injected into the tuyeres of the blast furnace, and the amount of pulverized coal injected, the oxygen enrichment rate of the tuyeres, and the theoretical combustion temperature of the tuyeres are adjusted simultaneously to form a coupled smelting environment inside the blast furnace and achieve stable smelting under high pellet proportion conditions.
[0025] By preparing alkaline pellets with specific components (such as basicity, MgO, and SiO2) and excellent metallurgical properties (low reduction expansion rate and low reduction adhesion index), the structural stability of the pellets during reduction in the high-temperature zone of the blast furnace is fundamentally improved, preventing pellet pulverization or agglomeration and providing a raw material basis for maintaining high permeability. Using this optimized alkaline pellet as the core, it is blended with acidic pellets, sinter, and other materials in specific proportions to construct a comprehensive furnace charge with a high pellet proportion (65–100%) and relatively high basicity (1.45–1.60). This ensures the overall low-carbon properties of the furnace charge and, through chemical blending, enhances its performance in subsequent metallurgical processes such as softening and dripping, aligning with the final slag performance requirements. During blast furnace smelting, hydrogen-rich gas is injected into the tuyeres. Hydrogen acts as a strong reducing agent and a low-molecular-weight gas, and the reduction reaction product is water vapor, which does not increase the volume of the gas and diffuses rapidly. This efficiently enhances indirect reduction, directly replacing part of the carbon reduction and reducing CO2 generation from the source of the chemical reaction. Simultaneous and precise control of the pulverized coal injection rate, oxygen enrichment rate, and theoretical combustion temperature ensures sufficient and stable high-temperature heat in the tuyeres area, compensating for the potential localized cooling effect of hydrogen reduction and ensuring complete gasification of the pulverized coal. Controlling the theoretical combustion temperature within a specific high-temperature range (2000–2200℃) maintains ample heat reserves and activity in the hearth, which is the thermodynamic basis for the smooth operation of the blast furnace. Optimized pellets combined with high-basicity feedstock improved the original structure and high-temperature performance of the blast furnace charge. Simultaneously, the hydrogen-rich gas and the oxygen-enriched tuyeres produced gas with superior reducing power and flowability. These two factors synergistically reduced the resistance of the gas passing through the charge, fundamentally addressing the core bottleneck of increased pressure differential caused by a high proportion of pellets, thus providing conditions for smooth blast furnace operation. With improved permeability, the reducing potential of the hydrogen-rich gas was fully realized, forming a highly efficient synergistic reduction system with some solid carbon (coke, pulverized coal). This made it possible to significantly reduce carbon consumption per ton of iron (fuel ratio) while maintaining high and stable blast furnace production, thereby directly and effectively reducing CO2 emissions from the blast furnace ironmaking system.
[0026] In some embodiments, the alkaline pellets satisfy the following: The alkalinity is 1.1–1.5, the reduction expansion rate is less than 13%, and the reduction adhesion index is less than 18%. The mass fraction of MgO is 0.5% to 3.0%, and the mass fraction of SiO2 is 2.5% to 6.0%.
[0027] The basicity of alkaline pellets, ranging from 1.1 to 1.5, provides a chemical basis for constructing high-basicity composite furnace charge. The higher basicity of alkaline pellets compared to conventional acidic pellets allows them to effectively contribute to basicity when mixed with acidic pellets and sinter, helping the composite furnace charge achieve the target basicity range of 1.45 to 1.60.
[0028] The reduction expansion rate of alkaline pellets (below 13%) and the reduction caking index (below 18%) together ensure the permeability inside the blast furnace. Under conditions of high pellet proportion, the low reduction expansion rate ensures the volume stability of the alkaline pellets during blast furnace reduction, reducing the risk of pulverization; the low reduction caking index prevents adhesion between alkaline pellets. These two characteristics work synergistically to maintain the pore structure of the burden column, thereby supporting the formation of a stable coupled smelting environment inside the blast furnace and achieving stable smelting.
[0029] The control of MgO mass fraction (0.5%–3.0%) and SiO2 mass fraction (2.5%–6.0%) in alkaline pellets serves to control slag performance and accurately calculate basicity, respectively. The introduction of MgO directly contributes to the slag composition, helping to achieve a MgO to Al2O3 mass ratio of 0.50–0.60, thereby optimizing slag fluidity and desulfurization / alkali removal capabilities. SiO2 content is the core variable for basicity calculation; controlling the SiO2 mass fraction within the range of 2.5%–6.0% ensures the controllability of the basicity of the alkaline pellets themselves and provides an accurate chemical basis for adjusting the overall basicity of the furnace charge.
[0030] In some embodiments, the total mass of the pellets is 65% to 100% of the mass of the composite furnace charge, and the basicity of the composite furnace charge is 1.45 to 1.60.
[0031] The total mass of pellets is the sum of the masses of alkaline and acidic pellets. A total mass ratio of 65% to 100% for pellets directly defines the technological characteristics of high-proportion pellet smelting. This high proportion range minimizes the use of traditional blast furnace raw materials such as sinter, and utilizes the low carbon emission advantage of the pellet production process from the source, laying a structural foundation for achieving low fuel ratio and low carbon dioxide emissions in the overall smelting process.
[0032] A comprehensive basicity of 1.45 to 1.60 provides the necessary chemical environment for high-proportion pellet smelting. This basicity range is higher than that of conventional blast furnace burdens. On the one hand, it can effectively neutralize the increase in overall acidity of the burden that may be caused by a significant increase in the proportion of pellets, avoiding excessive acidity in the slag, thereby ensuring that the final slag basicity can meet the requirement of 1.1 to 1.2. On the other hand, the higher comprehensive basicity of the burden helps to improve the metallurgical properties of the burden at high temperatures, especially the structure of the softening zone. This works synergistically with the low reduction expansion and low bonding characteristics of alkaline pellets to jointly maintain the permeability of the lower part of the blast furnace.
[0033] In some embodiments, the smelting process yields slag that satisfies the following conditions: basicity of 1.1 to 1.2 and mass ratio of MgO to Al2O3 of 0.50 to 0.60.
[0034] A slag basicity of 1.1 to 1.2 is a core indicator for assessing the balance between slag chemical properties and the smelting process. This basicity range reflects the final result after the overall burden basicity of 1.45 to 1.60 undergoes high-temperature physicochemical reactions within the blast furnace. Maintaining slag basicity within this target range ensures good desulfurization capacity and effectively controls the sulfur content in pig iron. Simultaneously, slag at this basicity has a suitable melting point and viscosity, facilitating smooth slag discharge and stabilizing the thermal state of the lower blast furnace hearth.
[0035] The mass ratio of MgO to Al2O3 in slag, between 0.50 and 0.60, is a key parameter for optimizing the slag's physicochemical properties. This ratio directly affects the slag's fluidity and stability. An appropriate amount of MgO can effectively reduce slag viscosity and improve its fluidity, while controlling the MgO to Al2O3 ratio can prevent excessive stickiness or deformation of the slag due to excessive Al2O3 content. Optimized fluidity ensures effective separation and smooth discharge of slag and molten iron, which is fundamental to the smooth operation of the blast furnace. Simultaneously, good slag properties provide the necessary lower conditions for the formation and maintenance of a coupled smelting environment within the blast furnace.
[0036] In some embodiments, the composite charge also includes one or more of lump ore, direct reduced iron, pre-reduced pellets, scrap steel, and cold-pressed briquettes.
[0037] Under the premise of ensuring that alkaline pellets are the core material, the total proportion of pellets is maintained at 65% to 100%, and the overall basicity of the furnace charge reaches 1.45 to 1.60, lump ore, direct reduced iron, pre-reduced pellets, scrap steel, or cold-pressed briquettes are allowed to be added. This allows the method to adapt to different resource conditions and market supply, providing more feedstock options for practical operation. Lump ore usually refers to lumpy ore obtained after crushing and screening natural iron ore, and is one of the traditional iron-containing raw materials for blast furnace ironmaking. In the embodiments of this application, lump ore is used in combination with pellets and sinter to adjust the overall basicity, chemical composition, and permeability of the raw materials fed into the furnace. Direct reduced iron and pre-reduced pellets, due to their high degree of metallization, can reduce the heat consumption of direct reduction of iron oxides in the blast furnace; scrap steel, as a pure source of metallic iron, mainly consumes physical heat during melting; cold-pressed briquettes are often used to recover iron-containing dust. By rationally incorporating these materials, the overall energy demand and gas distribution of the blast furnace can be adjusted, creating conditions for further optimizing the coupled smelting environment in conjunction with operations such as hydrogen-rich gas injection and theoretical combustion temperature control.
[0038] In some embodiments, the feeding operation further includes adding fuel and flux to the composite charge.
[0039] Adding fuel provides the necessary heat source, reducing agent, and permeable framework for the blast furnace smelting process. Under conditions with a high proportion of pellets, the proportion of sinter in the overall burden is significantly reduced, and sinter typically carries some fuel. Controlled fuel addition through the charging operation can directly replenish the reducing agent and heat required in the upper region of the blast furnace, and utilize fuel lumps (especially coke) to form a stable permeable framework within the furnace. This is a key physical measure that works in conjunction with the low-reduction expansion characteristics of alkaline pellets to maintain good permeability throughout the burden column, thereby supporting the formation of the coupled smelting environment.
[0040] Adding flux is a final component fine-tuning process to achieve the desired final slag performance. Although the target basicity and composition of the overall furnace charge have been set, the raw material composition may fluctuate in actual production. By adding flux during the charging stage, the total chemical composition of the charge can be adjusted online and flexibly. This is a direct and effective means to ensure that the final slag consistently meets the final performance targets of a slag basicity of 1.1 to 1.2 and an MgO to Al2O3 mass ratio of 0.50 to 0.60.
[0041] In some embodiments, the injection rate of the hydrogen-rich gas is 10 Nm³. 3 / t iron ~ 300Nm 3 / t iron, wherein the pulverized coal injection rate is 200kg / t iron to 300kg / t iron.
[0042] Hydrogen-rich gas injection rate 10 Nm 3 / t iron ~ 300Nm 3Iron production per ton is crucial for achieving enhanced gas reduction and pressure differential control within the blast furnace. Injecting hydrogen-rich gas into the blast furnace tuyeres allows the hydrogen component to act as a clean reducing agent, effectively participating in the indirect reduction of iron oxides and partially replacing the reduction function of carbon, thereby reducing carbon dioxide generation at the source. Simultaneously, the injection of hydrogen-rich gas alters the gas composition and combustion characteristics of the tuyeres' vortex zone, helping to optimize gas distribution and reduce the resistance of the lower blast furnace burden. This is essential for overcoming the pressure differential increase problem that can easily result from simply increasing the proportion of pellets.
[0043] A pulverized coal injection rate of 200 to 300 kg / ton of iron is fundamental to ensuring the thermal regime and carbon source supply in the lower part of the blast furnace. Maintaining this range of pulverized coal injection, while implementing hydrogen-rich injection, provides the blast furnace with the necessary heat, reducing agent, and carburizing agent. The combustion of pulverized coal before the tuyeres provides the main heat source for the smelting process, and its gasification product (CO) is one of the main reducing gases. This injection rate range ensures that even with reduced coke consumption in high-proportion pellet smelting, the blast furnace, especially the hearth region, still has a sufficient and stable heat supply and reducing atmosphere.
[0044] In some embodiments, the oxygen enrichment rate of the air vent is 4% to 8%, and the theoretical combustion temperature of the air vent area is 2000℃ to 2200℃.
[0045] A tuyere oxygen enrichment rate of 4% to 8% is crucial for achieving intensified smelting in the lower part of the blast furnace and for controlling the composition of the blast gas. Increasing the oxygen concentration in the blast accelerates the combustion of carbonaceous fuels (including pulverized coal and some coke) in front of the tuyere, thereby increasing the heat generated per unit blast and raising the hearth temperature. Simultaneously, oxygen enrichment reduces the proportion of nitrogen in the gas produced per unit of pig iron, which helps increase the concentration of reducing gas components in the gas and enhances its reducing capacity. This is essential for coordinating with hydrogen-rich gas injection and optimizing the overall reduction process in the blast furnace.
[0046] The theoretical combustion temperature of 2000℃ to 2200℃ in the tuyeres is a direct indicator for ensuring the stability of the blast furnace hearth thermal regime and the efficient combustion of pulverized coal. Controlling the theoretical combustion temperature within this range ensures, firstly, that the injected pulverized coal can burn fully in the tuyeres vortex zone, providing the blast furnace with the necessary and concentrated high-temperature heat. This is fundamental to maintaining ample heat reserves in the hearth and ensuring good slag-iron separation and fluidity. Secondly, this temperature range, matched with the pulverized coal injection rate and the hydrogen-rich gas injection rate, is a necessary control target for maintaining stable operation in the lower part of the blast furnace and preventing fluctuations in furnace conditions due to excessively high or low temperatures.
[0047] In some embodiments, the hydrogen-rich gas is at least one of coke oven gas, hydrogen, natural gas, syngas, and hydrogen-containing gases.
[0048] Coke oven gas is a common byproduct of integrated iron and steel enterprises. Hydrogen can be specially produced industrial hydrogen, natural gas is a widely available fossil fuel, syngas can be produced through coal or biomass gasification, and hydrogen-containing gases encompass hydrogen-containing byproduct gases from other industrial sectors. Allowing the use of one or more of these gases enables the high-proportion hydrogen-enriched blast furnace pellet coupled smelting method to select the most suitable or economical hydrogen-enriched gas supply scheme based on the energy structure, resource endowment, and cost factors of different regions and enterprises, significantly improving the industrial applicability and promotion potential of this method. Regardless of the specific type of hydrogen-enriched gas used, these gases share the common characteristic of containing hydrogen components that can effectively participate in the reduction reaction. Injecting such gases into the blast furnace through tuyeres is one of the key operations for achieving a coupled smelting environment. As a clean reducing agent, hydrogen can partially replace the role of carbonaceous reducing agents, directly contributing to reducing fuel consumption and carbon dioxide emissions in blast furnace smelting.
[0049] In some embodiments, the volume fraction of hydrogen in the hydrogen-containing gas is greater than 40%.
[0050] A hydrogen integral of over 40% is a fundamental prerequisite for ensuring sufficient reducing power and chemical activity in hydrogen-rich gas. This concentration requirement ensures that, regardless of the specific gas source, the content of hydrogen, the main active component, remains at a high level when injected into the blast furnace as "hydrogen-rich gas." High concentrations of hydrogen significantly enhance the indirect reduction capacity of coal gas for iron oxides, more effectively replacing the reduction function of carbon. This is a key chemical basis for achieving the core objectives of reducing fuel ratios and carbon dioxide emissions.
[0051] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national / industry standards; if there is no corresponding national / industry standard, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.
[0052] Example 1 The alkalinity of the alkaline pellets was adjusted to 1.1, and the chemical composition included 0.92% MgO, 2.39% SiO2, a reduction expansion index of 12%, a reduction binding index of 16%, and a reduction degree of 80%.
[0053] The composite furnace charge consists of basic pellets, acidic pellets, sinter, and a small amount of lump ore. The specific proportions (by mass percentage) are: 35% basic pellets, 30% acidic pellets, 30% sinter, and 5% lump ore. Therefore, the total proportion of pellets (the sum of basic and acidic pellets) in the composite furnace charge is 65%, and the basicity of the composite furnace charge is 1.50. Through the above proportions and flux adjustments, the binary basicity (CaO / SiO2) of the final slag is controlled at 1.16, and the MgO / Al2O3 ratio is 0.59, meeting the requirements for good fluidity and desulfurization.
[0054] The prepared composite charge and coke are fed into the blast furnace together through the blast furnace top charging system. During the smelting process, coke oven gas is injected into the furnace as a hydrogen-rich gas through the blast furnace tuyeres, with the injection rate controlled at 10 Nm³. 3 / ton of molten iron. The amount of pulverized coal injected into the blast furnace is simultaneously controlled at 280 kg / ton of molten iron, and the oxygen enrichment rate of the blast is set to 5.5%. Through the coordinated adjustment of the above operating parameters, the theoretical combustion temperature of the blast furnace tuyeres is maintained at 2010℃.
[0055] Compared with traditional operations where no hydrogen-rich gas is injected and the proportion of pellets is less than 60%, the blast furnace internal pressure difference is reduced by 10 kPa and the permeability index is increased by 11% when using the technical solution of this embodiment for smelting. At the same time, the blast furnace fuel consumption is reduced by 6 kg / ton of molten iron, and the corresponding carbon dioxide emissions are reduced by about 40 kg / ton of molten iron.
[0056] Example 2 The alkalinity of the alkaline pellets was adjusted to 1.35, the MgO content was 1.6%, the SiO2 content was 3.3%, the reduction expansion index was 10%, the reduction binding index was 13%, and the degree of reduction was 84%.
[0057] The composite furnace charge consists of basic pellets and sinter. The specific ratio (by mass percentage) is 80% basic pellets and 20% sinter. Therefore, the total proportion of pellets in the composite furnace charge is 80%, and the basicity of the composite furnace charge is 1.48. Through the above ratio and flux adjustment, the binary basicity (CaO / SiO2) of the final slag is controlled at 1.16, and the MgO / Al2O3 ratio is 0.58, meeting the requirements for good fluidity and desulfurization.
[0058] The prepared composite charge, along with coke and coke, is charged into the blast furnace via the top charging system. During the smelting process, coke oven gas is injected into the furnace as a hydrogen-rich gas through the blast furnace tuyeres, with the injection rate controlled at 150 Nm³. 3 / ton of molten iron. The amount of pulverized coal injected into the blast furnace is simultaneously controlled at 245 kg / ton of molten iron, and the oxygen enrichment rate of the blast is set to 6.5%. Through the coordinated adjustment of the above operating parameters, the theoretical combustion temperature of the blast furnace tuyeres is maintained at 2000℃.
[0059] The smelting method described in this embodiment, compared with the traditional operation of not injecting hydrogen-rich gas and having a pellet ratio of less than 60%, reduces the internal pressure difference of the blast furnace by 30 kPa and increases the permeability index by 15%. At the same time, the fuel consumption of the blast furnace is reduced by 60 kg / ton of molten iron, and the corresponding carbon dioxide emissions are reduced by 135 kg / ton of molten iron.
[0060] Example 3 The alkalinity of the alkaline pellets was adjusted to 1.5, the MgO content was 2.0%, the SiO2 content was 4.5%, the reduction expansion index was 9%, the reduction binding index was 11%, and the degree of reduction was 86%.
[0061] The composite furnace charge uses 100% alkaline pellets as the sole iron-containing raw material, with a composite basicity of 1.45. The final slag has a binary basicity (CaO / SiO2) of 1.19 and an MgO / Al2O3 ratio of 0.65, meeting the requirements for good fluidity and desulfurization.
[0062] The aforementioned combined furnace charge, along with coke and coke, is charged into the blast furnace via the blast furnace top charging system. During the smelting process, coke oven gas is injected into the furnace as a hydrogen-rich gas through the blast furnace tuyeres, with the injection rate controlled at 300 Nm³. 3 / ton of molten iron. The amount of pulverized coal injected into the blast furnace is simultaneously controlled at 200 kg / ton of molten iron, and the oxygen enrichment rate of the blast is set to 8.0%. Through the coordinated adjustment of the above operating parameters, the theoretical combustion temperature of the blast furnace tuyeres is maintained at 1995℃.
[0063] The smelting method described in this embodiment, compared with the traditional operation of not injecting hydrogen-rich gas and having a pellet ratio of less than 60%, reduces the internal pressure difference of the blast furnace by 60 kPa and increases the permeability index by 23%. At the same time, the blast furnace fuel consumption is reduced by 150 kg / ton of molten iron, and the corresponding carbon dioxide emissions are reduced by 500 kg / ton of molten iron.
[0064] Furthermore, one or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages: This invention achieves synergistic carbon reduction benefits by systematically coupling the low-carbon raw material advantage of high-proportion pellets (65%-100%) with the clean reduction advantage of hydrogen-rich gas injection.
[0065] The embodiments of the present invention allow the composite furnace charge to include a variety of iron-containing materials and allow the use of a variety of hydrogen-rich gases, which gives the technical solution strong resource compatibility and industrial adaptability.
[0066] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.
Claims
1. A method for coupled hydrogen-rich smelting of high-proportion blast furnace pellets, characterized in that, The method includes: Alkaline pellets with optimized metallurgical properties are mixed with acidic pellets and / or sinter to obtain a composite furnace charge with a high proportion of pellets. The composite charge is fed into the blast furnace for smelting. During the smelting process, hydrogen-rich gas is injected into the tuyeres of the blast furnace, and the amount of pulverized coal injected, the oxygen enrichment rate of the tuyeres, and the theoretical combustion temperature of the tuyeres are adjusted simultaneously to form a coupled smelting environment inside the blast furnace, thereby achieving stable smelting under conditions of high pellet proportion.
2. The method according to claim 1, characterized in that, The alkaline pellets satisfy the following: The alkalinity is 1.1–1.5, the reduction expansion rate is less than 13%, and the reduction adhesion index is less than 18%. The mass fraction of MgO is 0.5% to 3.0%, and the mass fraction of SiO2 is 2.5% to 6.0%.
3. The method according to claim 1, characterized in that, The total mass of the pellets is 65% to 100% of the mass of the composite furnace charge, and the basicity of the composite furnace charge is 1.45 to 1.
60.
4. The method according to claim 1, characterized in that, The slag obtained after smelting has the following properties: basicity of 1.1 to 1.2 and mass ratio of MgO to Al2O3 of 0.50 to 0.
60.
5. The method according to claim 1, characterized in that, The composite furnace charge also includes one or more of lump ore, direct reduced iron, pre-reduced pellets, scrap steel, and cold-pressed briquettes.
6. The method according to claim 1, characterized in that, The feeding operation also includes adding fuel and flux to the composite charge.
7. The method according to claim 1, characterized in that, The injection rate of the hydrogen-rich gas is 10 Nm. 3 / t iron ~ 300Nm 3 / t iron, wherein the pulverized coal injection rate is 200kg / t iron to 300kg / t iron.
8. The method according to claim 1, characterized in that, The oxygen enrichment rate of the air vent is 4% to 8%, and the theoretical combustion temperature of the air vent area is 2000℃ to 2200℃.
9. The method according to claim 1, characterized in that, The hydrogen-rich gas is at least one of coke oven gas, hydrogen, natural gas, syngas, and hydrogen-containing gases.
10. The method according to claim 9, characterized in that, The hydrogen-containing gas has a volume fraction of more than 40%.