A method and apparatus for co-producing iron and gas using Joule heat-driven processes that can achieve self-termination.

Abstract

This invention relates to the field of ironmaking technology, specifically to a method and apparatus for self-terminating Joule-driven ironmaking and gas co-production, aiming to solve the technical problems of high energy consumption, large carbon emissions, and long reaction cycles in traditional ironmaking processes. This invention uses green electricity as a driving force, utilizing the Joule effect to achieve direct reduction ironmaking from iron ore powder. The reaction self-termination is achieved through a system short circuit triggered by the formation of the metallic phase, simultaneously completing the efficient co-recovery of gas. The process employs a carbon-based conductive reducing agent for direct heating, eliminating heat transfer losses and increasing the reaction rate. The green electricity supply aligns with the requirements of dual-carbon development, the product has high purity of metallic iron particles, and the gas recovery value is significant. The apparatus achieves continuous operation and has a compact structure, providing a new technical path for the green and low-carbon transformation of the ironmaking industry.

Description

Technical Field

[0001] This invention relates to the field of ironmaking technology, specifically to a method and apparatus for co-producing iron and gas using Joule heat-driven processes that can achieve self-termination. Background Technology

[0002] The steel industry is a fundamental pillar industry of the national economy. Ironmaking, as the core process in steel production, directly determines the industry's energy consumption, carbon emissions, and resource utilization efficiency through its technological level. Currently, traditional ironmaking processes mainly rely on blast furnace ironmaking, supplemented by non-blast furnace ironmaking processes such as rotary hearth furnaces and rotary kilns. Among these, blast furnace ironmaking holds a dominant position in the industry due to its mature technology system, but its production process suffers from many insurmountable technical defects. Non-blast furnace ironmaking processes have also not fundamentally solved the core issues of energy consumption, carbon emissions, and resource utilization.

[0003] Blast furnace ironmaking uses coke as the main reducing agent and heat source. Iron ore powder needs to be sintered into pellets or lumps before being fed into the furnace. The iron is then reduced and smelted under high temperature and pressure in conjunction with coke. This entire process not only relies on high-quality coking coal resources but also suffers from high energy consumption and a long process flow. Heat transfer in blast furnace ironmaking is primarily indirect. Heat generated from fuel combustion is transferred to the materials inside the furnace via radiation from the furnace wall and convection from flue gas. A large amount of heat is lost with blast furnace gas and cooling wastewater, resulting in low energy efficiency and high energy consumption per unit of product. Simultaneously, the large-scale combustion of fossil fuels such as coke produces significant amounts of carbon dioxide, leading to high carbon emission intensity, which contradicts the national "dual-carbon" development goals and makes it difficult to meet the requirements of the ironmaking industry's green and low-carbon transformation. Furthermore, although some of the blast furnace gas produced during ironmaking can be recovered and reused, technological limitations result in low gas recovery efficiency and high purification difficulty, failing to fully exploit its energy value.

[0004] Non-blast furnace ironmaking processes, such as direct reduction ironmaking in rotary hearth furnaces, simplify the process flow and have a relatively wide range of raw material adaptability, but they still cannot get rid of the traditional indirect heating mode. They mostly use gas or pulverized coal combustion for heating, resulting in significant heat loss and limited improvement in energy utilization. Moreover, the internal space utilization of rotary hearth furnaces is low, the material laying method is limited, and the processing efficiency is difficult to improve significantly. At the same time, the use of fossil fuels still leads to high carbon emissions.

[0005] To address the technical bottlenecks of traditional ironmaking processes, the industry has conducted numerous studies and improvements, such as optimizing blast furnace structures, developing new reducing agents, and improving the efficiency of gas recovery systems. However, these improvements are mostly localized optimizations of traditional processes and have not fundamentally changed the core model of indirect heating and reliance on fossil fuels. The problems of high energy consumption and large carbon emissions remain unresolved. Furthermore, existing ironmaking processes struggle to achieve precise self-termination of the reaction process, and external control measures can easily lead to energy waste or incomplete reactions. Moreover, the synergy between ironmaking and gas recovery is poor, failing to achieve efficient, tiered utilization of resources.

[0006] Therefore, developing a novel ironmaking technology that breaks away from the traditional indirect heating mode, is driven by clean energy, enables self-termination of the reaction, and can simultaneously recover coal gas is crucial for promoting the green, low-carbon, efficient, and high-quality development of the ironmaking industry. This invention, based on the Joule effect, uses green electricity to achieve direct reduction ironmaking from iron ore powder, utilizes the inherent characteristics of the reaction to achieve self-termination, and simultaneously achieves efficient recovery of coal gas. It fundamentally solves the core technical defects of traditional ironmaking processes and possesses significant technological innovation and industrial application value. Summary of the Invention

[0007] The purpose of this invention is to provide a Joule-driven co-production method and apparatus for ironmaking and coal gas that can achieve self-termination, so as to solve the technical problems of high energy consumption, large carbon emissions, low coal gas recovery efficiency and difficulty in precise control of reaction process in existing ironmaking processes, and to realize green, low-carbon, high-efficiency and high-quality ironmaking process, as well as the synergistic and cascaded utilization of ironmaking and coal gas.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a self-terminating Joule-driven co-production method for ironmaking and coal gasification.

[0009] Includes the following steps:

[0010] S1 Preparation of carbon-based conductive reducing agent: After crushing biomass, it is mixed with industrial coke powder at a mass ratio of 0%-60% and 40%-100% to obtain a carbon-based conductive reducing agent.

[0011] S2 Raw material drying and mixing: After drying the iron ore powder and the carbon-based conductive reducing agent obtained in step S1 to a moisture content of ≤2%, they are mixed evenly at a mass ratio of 70~100:20~40 to obtain the reaction raw materials.

[0012] S3 Joule self-terminating reaction: The mixed reaction materials are fed into the reaction zone of a vertical furnace via a chain drive. A mechanical load is applied by a hydraulic device to tightly bind the materials and form a conductor. An inert gas is introduced into the furnace to create an inert atmosphere. Then, green electricity is introduced, and pulse impacts are applied to the conductor through a fixed electrode at the bottom and a sliding electrode at the top, triggering the Joule effect to generate high temperature and achieve direct reduction of iron ore powder. As the reduction reaction proceeds, the metal phase is continuously generated in the furnace. When the metal phase reaches a certain content, the system short-circuits, the Joule effect automatically stops, and the reaction is self-terminating.

[0013] S4 Product Crushing and Magnetic Separation: The reaction product is discharged from the vertical furnace and crushed and dissociated by the crushing device. Then it is classified by the magnetic separation device to obtain high-purity metallic iron particles and carbon-rich slag phase. The carbon-rich slag phase can be returned to the system for recycling.

[0014] S5 Coal Gas Co-recovery: Coal gas generated during the ironmaking process is continuously discharged from the coal gas outlet at the top of the vertical furnace and enters the coal gas recovery device for efficient recovery. The recovered coal gas can be recycled as energy fuel.

[0015] The present invention also proposes a Joule-driven co-production device for ironmaking and gasification that can achieve self-termination.

[0016] Specifically, it includes a chain drive system, a Joule heating drive system, a sample reaction cell, a gas recovery device, a crushing device, and a magnetic separation device. Each component is linked together in sequence to form a complete operation chain.

[0017] The chain drive system includes a feeder, a transmission and conveying unit, and a discharge mechanism. It is equipped with a load self-termination function and a gas recovery adaptation structure to realize continuous feeding of reaction raw materials and continuous discharge of reaction products, adapting to the continuous operation requirements of vertical furnaces.

[0018] The Joule heating drive system includes a DC power supply, a controllable current source, a bottom fixed electrode, and a top sliding electrode. The bottom fixed electrode is located at the bottom of the sample reaction cell, and the top sliding electrode is connected to the upper static load input structure of the sample reaction cell and can move synchronously to ensure close contact with the conductor. This system is used to apply pulse impacts to the raw materials in the sample reaction cell to trigger the Joule effect and generate high temperature.

[0019] The sample reaction cell has a vertical furnace structure with a closed furnace design. The furnace cavity is an inert atmosphere cavity to avoid oxidation of raw materials and products. The furnace body is equipped with an upper static load input structure connected to the top sliding electrode. A hydraulic device is used to provide a stable mechanical pressure load to the raw materials in the furnace, so that the raw materials are tightly bound to form a conductor. The upper part of the furnace body integrates a gas outlet for exporting the gas generated during the ironmaking process.

[0020] The gas recovery device is sealed and connected to the gas outlet at the top of the furnace body, and is used to receive and recover the recoverable gas generated during the ironmaking process, so as to realize the cascade utilization of the gas.

[0021] The crushing device and the magnetic separation device are connected in sequence. The crushing device is used to dissociate the reaction products, and the magnetic separation device is used to classify and recover the crushed materials to obtain high-purity metallic iron particles and carbon-rich slag phase.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. Breaking away from traditional indirect heating mode, significantly improving energy utilization efficiency: This invention utilizes the Joule effect to achieve direct heating. The mixed system of iron ore powder and carbon-based conductive reducing agent is used as a conductor. After green electricity is introduced, it realizes the conversion of electrical energy into heat energy, completely eliminating the energy loss caused by heat radiation and heat convection in the traditional indirect heating process, greatly improving energy utilization efficiency and reducing energy consumption per unit product.

[0024] 2. Green electricity drives low-carbon and environmental protection, meeting the requirements of dual-carbon development: This invention uses green electricity as the main energy source to replace traditional fossil fuels such as coke and gas, reducing carbon dioxide emissions at the source. At the same time, biomass is added to the carbon-based conductive reducing agent to replace part of the coke powder, further reducing the consumption of fossil resources, which is in line with the national "dual-carbon" development goals and the requirements of the green and low-carbon transformation of the ironmaking industry.

[0025] 3. Automatic termination of reaction, precise process control and energy saving: This invention utilizes the system short circuit caused by the formation of the metal phase during the reduction of iron ore powder to achieve automatic termination of the reaction. There is no need to set up additional temperature and time control devices to regulate the reaction endpoint. This not only reduces the difficulty of process control, but also avoids energy waste or incomplete reaction caused by external control deviations, further improving the energy saving of the process and the stability of product quality.

[0026] 4. Co-processing of ironmaking and coal gas to achieve tiered utilization of resources: While realizing the reduction of iron ore powder for ironmaking, this invention achieves efficient co-processing of coal gas through a coal gas recovery device at the top of the furnace. The recovered coal gas can be recycled as energy fuel, and the carbon-rich slag phase can also be returned to the system for reuse, realizing tiered and efficient utilization of resources in the ironmaking process and improving the overall economic benefits of the process.

[0027] 5. High product purity, compact equipment, and strong continuous operation capability: This invention uses the Joule effect for direct heating, avoiding the introduction of external impurities, resulting in high purity iron particles with significant value for subsequent processing and utilization; the equipment adopts a chain drive system combined with a vertical furnace body, which is compact in structure and has high space utilization, enabling continuous transmission of reaction raw materials and continuous operation of the ironmaking process, making it suitable for large-scale industrial application. Attached Figure Description

[0028] Figure 1 Bar charts showing the reduction efficiency of comparative examples 1, 2, 3, and 4;

[0029] Figure 2 Bar graphs showing the reduction efficiency of Comparative Examples 2, 5, 6, 7, 8 and Example 1;

[0030] Figure 3 The reaction time-temperature curves for Example 1 and Comparative Example 7 are shown below.

[0031] Figure 4Bar graphs showing the iron purity of Example 1 and Comparative Example 11;

[0032] Figure 5 (a) A physical image of the metallic iron product obtained by the method of the present invention; Figure 5 (b) Microscopic image of the metallic iron product obtained by the method of the present invention;

[0033] Figure 6 This invention provides a bar chart showing the proportions of various components in coal gas obtained using the method of this invention.

[0034] Figure 7 This is a schematic diagram of the device structure of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] The technical solution adopted in this invention is as follows:

[0037] Step 1: Preparation of carbon-based conductive reducing agent: After crushing biomass, it is mixed with industrial coke powder in a certain proportion to obtain carbon-based conductive reducing agent; the biomass is crushed in a shear crusher, and the mass percentage of each component in the carbon-based conductive reducing agent is: biomass 0%-60%, industrial coke powder 40%-100%.

[0038] Step 2: Raw material drying and mixing: The iron ore powder and the prepared carbon-based conductive reducing agent are dried separately until the moisture content is ≤2%, then uniformly mixed to obtain the reaction raw materials; the mass ratio of iron ore powder to carbon-based conductive reducing agent is 70~100:20~40.

[0039] Step 3: Joule self-termination reaction: The mixed reaction raw materials are fed into the reaction zone of the vertical furnace through a chain drive. Mechanical load is applied to make the raw materials tightly bonded to form a conductor. Green electricity is introduced under an inert atmosphere to trigger the Joule effect to reduce iron ore powder. When the metal phase is generated and causes a short circuit in the system, the reaction is self-terminating.

[0040] Step 4: Product crushing and magnetic separation: The reaction product is crushed and then classified by magnetic separation to obtain metallic iron particles and carbon-rich slag phase;

[0041] Step 5: Coal gas co-recovery: The coal gas generated during the ironmaking process is discharged from the exhaust port at the top of the vertical furnace and efficiently recovered through a coal gas recovery device.

[0042] To better understand the technology of the present invention, the following specific embodiments and comparative examples are provided.

[0043] Example 1

[0044] The raw material composition of this comparative example was: 30% conductive reducing agent (made from 30% corn stalks and 70% industrial coke powder) and 70% iron ore powder. The Joule heating device parameters were set as follows: temperature 1600℃, reaction time 40s, mechanical load, and the dezincification rate was tested after the reaction. At this time, the metallization rate was 95.74%, the reduction degree was 96.33%, and the reaction termination time was less than the set reaction time.

[0045] Comparative Examples 1-8

[0046]

[0047] Based on the data analysis in Table 1, the following conclusions can be drawn:

[0048] Comparative Examples 1, 2, 3, and 4 constitute a set of parallel control experiments. Figure 1 The data shows that the metallization rate and reduction degree significantly improve with increasing temperature, but excessively high temperatures cause excessive damage to the reactor. A temperature of 1400℃ is recommended.

[0049] Comparative Examples 2, 5, 6, 7, and 8 form a group of control experiments conducted at different time points. According to... Figure 2 Data analysis results show that the metallization rate and reduction degree increase significantly with the increase of current, with the reduction effect of Comparative Example 8 being particularly outstanding, and the metallization rate reaching 90.17%.

[0050] Example 1 is a set of experiments based on Comparative Example 7 with increased mechanical load. Combined with... Figure 3 Data analysis shows that the example exhibited a sudden temperature drop after 24 seconds, initiating a self-terminating experiment. This indicates a faster reaction and a slightly higher temperature than the comparative example 7, ultimately achieving a high dezincification rate and self-termination function in a shorter time.

[0051] Comparative Examples 9, 10, and 11

[0052] Comparative Examples 9, 10, and 11 are the results of experiments conducted using a tubular furnace to simulate a non-blast furnace traditional process: their data are recorded in Table 2. When the reaction proceeded for 10 minutes, the metallization rate reached 25.23%; after the reaction continued for 30 minutes, the metallization rate further increased to 91.54%.

[0053]

[0054] In summary, a comparison of the data in Tables 1 and 2 clearly shows that the direct heating method based on the Joule effect has a much shorter reaction time than the traditional ironmaking process, significantly shortening the reaction cycle and resulting in significantly higher reaction efficiency. Furthermore, the use of resistance heating and green electricity achieves higher energy utilization and lower carbon emissions.

[0055] pass Figure 5 It can be seen that the metallic iron product generated by the new method has a distinct iron particle structure, and its purity can reach over 90% (as tested). Figure 4 ),pass Figure 6 In the analysis of coal gas, the new methods of coal gas recovery mainly focus on reusable gases such as carbon monoxide and hydrogen.

[0056] The Joule effect driven ironmaking and gas co-production device used in this embodiment can achieve self-termination. The device includes: a chain drive system, a Joule heating drive system, a sample reaction tank, a gas recovery device, a crushing device and a magnetic separation device. Each component is linked in sequence to form a complete process operation link.

[0057] The chain drive system enables continuous feeding of reaction raw materials and continuous unloading of products. The chain drive system includes a feeder and a transmission and conveying unit. The drive system is equipped with a load self-termination function and a gas recovery device structure, which is suitable for the continuous operation requirements of vertical furnaces.

[0058] The sample reaction cell on the transmission and conveying unit is an independent vertical furnace structure (such as...). Figure 7 To ensure the sealing and inert atmosphere of each reaction unit, the feeder delivers the raw materials into the vertical reactor. After the reaction is completed, the lower electrode automatically avoids the material, which then falls from the vertical reactor into the ore crusher for crushing.

[0059] The Joule heating drive system includes a DC power supply, a controllable current source, a bottom fixed electrode, and a top sliding electrode. It is used to apply pulse impacts to the raw materials in the sample reaction cell and trigger the Joule effect. The top sliding electrode of the Joule heating drive system moves down synchronously with the static load input structure of the hydraulic device and is always in close contact with the conductor in the furnace to ensure stable triggering of the Joule effect.

[0060] The gas recovery device (gas recoverer) is sealed and connected to the gas outlet of the vertical furnace body, with no gas leakage and a recovery efficiency of ≥95%;

[0061] The crushing and magnetic separation units work together (the crushing unit is a crusher and the magnetic separation unit is a magnetic separator, respectively) to achieve efficient product dissociation and graded recovery. The entire unit has strong continuous operation capability, and the single batch processing capacity can be flexibly adjusted according to industrial needs.

[0062] The scope of protection of this invention is not limited to the above embodiments. For those skilled in the art, this invention can have various improvements and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for co-producing iron and gas using Joule heat-driven processes that can achieve self-termination, characterized in that, Includes the following steps: S1 Preparation of carbon-based conductive reducing agent: After crushing biomass, it is mixed with industrial coke powder in a certain proportion to obtain a carbon-based conductive reducing agent; S2 Raw material drying and mixing: The iron ore powder and the carbon-based conductive reducing agent obtained in step S1 are dried separately until the moisture content is ≤2%, and then mixed evenly to obtain the reaction raw materials; S3 Joule self-termination reaction: The mixed reaction raw materials are fed into the reaction zone of the vertical furnace through a chain drive. Mechanical load is applied to make the raw materials tightly bonded to form a conductor. Green electricity is introduced under an inert atmosphere to trigger the Joule effect to achieve the reduction of iron ore powder. When the metal phase is generated and causes a short circuit in the system, the reaction is self-terminating. S4 Product Crushing and Magnetic Separation: The reaction product is crushed and then classified by magnetic separation to obtain metallic iron particles and carbon-rich slag phase. S5 Coal Gas Co-recovery: Coal gas generated during the ironmaking process is discharged from the exhaust port at the top of the vertical furnace and efficiently recovered through a coal gas recovery device.

2. The method according to claim 1, characterized in that, In step S1, the biomass is crushed in a shear crusher, and the mass percentage of each component in the carbon-based conductive reducing agent is: biomass 0%-60%, industrial coke powder 40%-100%.

3. The method according to claim 1, characterized in that, In step S2, the mass ratio of iron ore powder to carbon-based conductive reducing agent is 70~100:20~40.

4. A Joule-heat-driven co-production apparatus for ironmaking and gasification that implements the method of any one of claims 1-3, characterized in that, It includes a chain drive system, a Joule heating drive system, a sample reaction cell, a gas recovery device, a crushing device, and a magnetic separation device. Each component is linked together to form a complete process chain. The chain drive system is used to realize the continuous transmission of reaction raw materials from feed to the output of reaction products; The Joule heating drive system includes a DC power supply, a controllable current source, a bottom fixed electrode, and a top sliding electrode, which are used to apply pulse impacts to the raw materials in the sample reaction cell and trigger the Joule effect. The sample reaction cell is a vertical furnace structure, equipped with an upper static load input structure and connected to the top sliding electrode. A hydraulic device is used to provide mechanical pressure load for the raw materials, and a gas outlet is integrated at the top of the furnace. The gas recovery device is connected to the gas outlet at the top of the furnace body and is used to receive and recover the recoverable gas generated during the ironmaking process. The crushing device and the magnetic separation device are connected in sequence for dissociating and classifying the reaction products.

5. The apparatus according to claim 4, characterized in that, The sample reaction cell adopts a closed furnace structure, and the inner cavity of the furnace is an inert atmosphere cavity to avoid oxidation of raw materials and products during the reaction process.

6. The apparatus according to claim 4, characterized in that, The top sliding electrode moves synchronously with the upper static load input structure to ensure close contact with the conductor and to ensure stable triggering of the Joule effect.

7. The apparatus according to claim 4, characterized in that, The chain drive system includes a feeder and a transmission and conveying unit. The chain drive system is equipped with a load self-termination function and a gas recovery device structure, which is suitable for the continuous operation requirements of vertical furnaces.

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