Electric arc furnace short-process steelmaking technology based on hydrogen energy auxiliary reduction

Abstract

The invention belongs to the technical field of metallurgy, and particularly relates to an electric arc furnace short-process steelmaking technology based on hydrogen energy auxiliary reduction. The process comprises the following steps: preparing a composite pellet with a core-shell structure; carrying out segmented temperature control pre-reduction on the pellets in a green hydrogen shaft furnace to obtain high-temperature pre-reduced pellets and tail gas; the tail gas is subjected to dust removal, catalytic reforming, dehydration and decarburization treatment to obtain hydrogen-rich reformed gas, most of the hydrogen-rich reformed gas is circulated back to the shaft furnace, and a small part of the hydrogen-rich reformed gas is used for electric furnace injection; the high-temperature pellets are hotly charged into an electric arc furnace to be smelted, and part of reformed gas is injected for collaborative refining; waste heat of flue gas of the shaft furnace is recycled for power generation, and electric furnace waste gas is used for preheating pellets. By means of raw material design, process synergy and system circulation, efficient utilization of hydrogen and carbon resources is achieved, and the method has the advantages of being high in metallization ratio (larger than or equal to 92%), low in energy consumption and carbon emission and excellent in molten steel quality.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and in particular relates to a short-process steelmaking process for electric arc furnace based on hydrogen-assisted reduction. Background Technology

[0002] The steel industry is a major contributor to energy consumption and carbon emissions. The traditional blast furnace-converter long-process steelmaking process results in high carbon emissions per ton of steel. While the electric arc furnace short-process, primarily using scrap steel, can reduce carbon emissions, its raw material preparation still relies on fossil fuels when using pig iron or direct reduced iron. Hydrogen-based shaft furnace direct reduction is an important direction for green ironmaking, but existing technologies suffer from low and unstable metallization rates (75%-85%), low hydrogen utilization rates (<60%), and high energy consumption due to poor integration between the shaft furnace and electric arc furnace. Furthermore, large amounts of CO2 and H2O in the reduction tail gas are not effectively utilized; direct emissions or simple treatment lead to resource waste and an increased carbon footprint. Therefore, developing a new short-process steelmaking technology that achieves efficient hydrogen utilization, internal carbon recycling, and deep synergy among various processes is crucial for the industry's green transformation. Summary of the Invention

[0003] The purpose of this invention is to provide a short-process steelmaking process for electric arc furnace based on hydrogen-assisted reduction, so as to solve the problems existing in the prior art.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] A short-process steelmaking process using an electric arc furnace based on hydrogen-assisted reduction includes the following steps:

[0006] S1. Pellet preparation: High-grade iron ore powder, reduction accelerator and binder are mixed and granulated to form a pellet core. Then, a shell material is wrapped around the outside of the pellet core. After drying and curing, composite pellets with a particle size of 10-15mm are obtained.

[0007] S2, Vertical Furnace Pre-reduction: The composite pellets are fed into the green hydrogen vertical furnace for segmented temperature-controlled pre-reduction to obtain high-temperature pre-reduced pellets and high-temperature tail gas;

[0008] S3, Exhaust Gas Reforming and Recirculation: High-temperature exhaust gas is sequentially treated with dust removal, catalytic reforming, dehydration, and CO2 removal to obtain hydrogen-rich reformed gas;

[0009] S4. Electric Arc Furnace Melting: High-temperature pre-reduced pellets are hotly charged into an electric arc furnace for melting; at the same time, a portion of hydrogen-rich reforming gas is injected into the molten pool of the electric arc furnace.

[0010] S5. Waste heat recovery: The waste heat from the flue gas of the green hydrogen vertical furnace and the waste heat from the exhaust gas of the electric arc furnace are recovered and used for power generation and preheating of pellets, respectively.

[0011] Furthermore, in step S1, the total iron content (TFe) of the high-grade iron ore powder is ≥68%; the reduction promoter is CaF2 or Na2CO3, which accounts for 0.5%-1.5% of the mass of the pellet core; and the binder is bentonite, which accounts for 2-4% of the mass of the pellet core.

[0012] Furthermore, in step S1, the shell material, based on the dry total mass of the shell material, consists of 80%-90% carbonaceous material, 5-15% porous skeleton material, 0.5-1% alkali metal compound, and 4-4.5% binder.

[0013] Furthermore, the carbonaceous material is metallurgical coke powder or biochar, the porous framework material is porous silica micro powder, and the alkali metal compound is potassium carbonate or sodium carbonate.

[0014] Furthermore, in step S2, the segmented temperature-controlled pre-reduction method involves a composite pellet layer thickness ≤ 1.2m, with a drying section, a main reduction section, and a homogenizing section sequentially arranged along the material's downward direction, wherein:

[0015] The controlled temperature of the drying section is 440-460℃;

[0016] The controlled temperature of the main reduction section is 635-665℃. The reducing gas introduced into the main reduction section is a mixture of high-purity green hydrogen and recycled hydrogen-rich reformed gas, with a hydrogen volume concentration ≥90% and an introduction flow rate of 80-120 Nm³. 3 A mixed gas with a pressure of 0.3-0.5 MPa and an axial velocity of 0.15-0.3 m / s, and uniformly distributed through a porous distribution plate with an opening ratio of 60%;

[0017] The temperature of the heat spreader is controlled at 830-870℃, and circulating CO gas is introduced. The percentage of circulating CO gas in the total gas volume of this section is ≤15%.

[0018] Furthermore, in step S3, catalytic reforming is a CO2-H2O co-reforming reaction carried out in a reforming reactor. The catalyst is a Ni-based catalyst, and the reaction temperature is 600-750℃. After reforming, 70%-80% of the hydrogen-rich reforming gas is returned to the main reduction section of the green hydrogen vertical furnace, and 20%-30% of the hydrogen-rich reforming gas is allocated for injection into the electric arc furnace molten pool.

[0019] Furthermore, in step S4, the hot charging temperature of the high-temperature pre-reduced pellets is ≥750℃, and the electric arc furnace melting process includes a melting period and a refining period, wherein:

[0020] The power supply during the melting period is 10-14MW, achieved through deep arc electrode operation and bottom-blown oxygen to aid melting;

[0021] The power supply during the refining period is reduced to 7-9MW, and a slag-forming agent is added to form slag. The slag thickness is controlled at 100-120mm, the final carbon content is controlled at 0.03-0.05%, the final temperature is 1630-1650℃, the binary basicity R of the final slag is controlled at 2.8-3.2, and the TFe content in the final slag is ≤8%.

[0022] Furthermore, in step S5, the waste heat from the flue gas is used to generate steam with a pressure ≥1.6MPa through a waste heat boiler for power generation, and the waste heat from the exhaust gas is used to preheat the pellets to be fed into the furnace to above 500°C.

[0023] The present invention has the following beneficial effects:

[0024] 1. Through the core-shell structure of the composite pellet design, the core promoter reduces the reduction activation energy, and the shell generates active reducing gas in situ in the preheating section and catalyzes, so that the metallization rate of the vertical furnace is stabilized at over 92% and the reduction uniformity is good.

[0025] 2. By using the tail gas CO2-H2O co-reforming technology, some CO2 and H2O are converted into CO and H2, achieving efficient circulation of carbon and hydrogen elements within the system. The comprehensive utilization rate of hydrogen is >95%, and some CO2 is recovered, thereby reducing carbon emissions.

[0026] 3. The hydrogen-rich reforming gas can be used in two ways (returning to the vertical furnace and the electric furnace), playing multiple roles in the electric furnace such as stirring, deoxidation and slag reduction, further improving energy efficiency and metal yield.

[0027] 4. By using a segmented temperature-controlled pre-reduction method, the thermodynamic and kinetic requirements of different stages of the hydrogen reduction reaction of iron oxides are adapted, thereby improving product quality and stabilizing the metallization rate. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] Example 1:

[0031] like Figure 1 As shown, a short-process steelmaking process using an electric arc furnace based on hydrogen-assisted reduction includes the following steps:

[0032] S1. Pellet preparation:

[0033] Pellet core preparation: High-grade iron ore powder (68.5% TFe, passing through a 200-mesh sieve, accounting for 95.8%), reduction accelerator (CaF2, accounting for 1.2%), and binder (bentonite, accounting for 3.0%) were dry-mixed in a mixer for 25 minutes. Then, water was added to form pellets in a disc pelletizer, controlling the moisture content of the green pellets to 8.5% and the particle size to 11-13 mm. The green pellets were dried at 200℃ for 40 minutes and preheated at 500℃ for 30 minutes using a chain grate machine to obtain pellet cores with a compressive strength ≥400 N / pellet.

[0034] The mechanism of action of reduction promoters CaF2 or Na2CO3 is as follows: the reduction of iron oxides (such as Fe2O3, Fe3O4) requires the breaking of strong Fe-O ionic bonds. At the reduction temperature, the added CaF2 or Na2CO3 cations (Ca... 2+ Na + These promoters can partially embed or adsorb onto the surface and grain boundaries of iron oxide lattices, thereby disrupting the lattice and lowering the activation energy. Additionally, these promoters can form a low-melting-point liquid phase (e.g., a fluorine- or sodium-containing silicate liquid phase) with iron oxides or gangue components (such as SiO2) at lower temperatures. This liquid phase wets solid particles and, on the one hand, acts as a fast channel for ion diffusion, accelerating the O2-O2 process. 2- On the one hand, the removal of iron oxides by hydrogen is achieved; on the other hand, the liquid phase covering can prevent the sintering and agglomeration of fine metallic iron particles formed in the early stage of reduction, maintaining a highly reactive surface. Through the above-mentioned effects of the reduction promoter, the apparent activation energy of hydrogen reduction of iron oxides is significantly reduced, enabling the main reduction reaction to achieve a high reaction rate at a relatively low temperature (635-665℃), thereby improving the thermodynamic driving force and kinetic rate of the reduction process.

[0035] Preparation of shell slurry (shell material): Take carbonaceous material (metallurgical coke powder, 80% dry basis) with a particle size <0.074mm and a specific surface area of ​​250m². 2 / g of porous framework material (porous silica micro powder, 15% dry basis) and alkali metal compound (potassium carbonate, 1% dry basis) are dry-mixed. Carboxymethyl cellulose (binder, 4% dry basis) is prepared into a 2% aqueous solution. The dry mixture is then mixed with the carboxymethyl cellulose aqueous solution to form a homogeneous slurry.

[0036] Coating: After activating the core pellets by spraying a small amount of water mist onto their surface, the pellets are placed in a roller coating machine to uniformly spray the above slurry onto the pellet surface (the amount of slurry is calculated based on its dry basis, ensuring that the dry basis mass of the slurry is approximately 15% of the composite pellet mass). After drying and curing, composite pellets with a particle size of 10-15 mm are obtained.

[0037] Mechanism of action of the outer shell material: When the composite pellets enter the drying and preheating sections (450-650℃) of the vertical shaft furnace, the carbonaceous material (metallurgical coke powder / biochar) in the outer shell reacts with water vapor (H2O) escaping from the furnace atmosphere or the pellet interior to produce a water-gas reaction (C + H2O → CO + H2). This reaction generates high concentrations of CO and H2 in situ within the pores of the pellet shell, thus creating in-situ gasification and constructing a locally strong reducing atmosphere. The added alkali metal compounds (K2CO3 / Na2CO3) are highly efficient catalysts for the water-gas reaction. + / Na + Ions significantly lower the activation energy of the carbon-water vapor reaction, enabling the reaction to start and be maintained rapidly at lower temperatures. This ensures that the surface of the pellets is coated with a highly reducing "gas film" before they enter the main reduction stage. Porous silica micropowder forms a robust and interconnected porous network. Its functions are threefold: first, to maintain the shell shape during drying and curing, preventing cracking; second, to provide stable channels for the diffusion of the aforementioned water-gas reaction and gaseous products (CO, H2); and third, to serve as an excellent carrier for alkali metal catalysts, preventing their loss or agglomeration and failure. This design ingeniously alters the reduction mode. Traditional pellet reduction relies entirely on externally introduced hydrogen gas, a diffusion-controlled process "from the outside in." In the composite pellets of this invention, the shell actively generates reducing gas through chemical reaction before the arrival of external hydrogen gas, forming a synergistic reduction state from the inside (shell reaction layer) to the outside (main reducing gas). This not only significantly improved the initial reduction rate of the pellet surface (outer shell and adjacent core region), breaking the bottleneck of diffusion limitation, but also made the reduction of the entire pellet more uniform and effectively eliminated the radial reduction gradient.

[0038] S2, Vertical shaft furnace pre-reduction

[0039] The composite pellets were added to the green hydrogen vertical furnace with a thickness of 1.0m.

[0040] Drying section: Temperature controlled at 440-460℃, residence time 30 minutes. The main purpose of this stage is to physically remove residual free water and some of the water of crystallization from the pellets, preventing excessive evaporation of moisture in the main reduction section, which would consume heat and dilute the reducing atmosphere. The gentle temperature prevents premature and violent reaction of the outer carbonaceous material.

[0041] Main reduction section: Temperature controlled at 635-665℃. A reducing gas mixture of fresh green hydrogen (99.9% purity) and recycled hydrogen-rich reformed gas is introduced, with an H2 concentration ≥92% in the mixture. The total gas flow rate is 100 Nm³. 3 / h·t pellets, pressure 0.4MPa, axial flow velocity controlled at 0.2m / s by a gas distribution plate (aperture ratio ~60%) inside the furnace. In this mid-temperature range, the hydrogen diffusion coefficient is high, and iron oxides, after modification with an accelerator, possess sufficient reduction reactivity at this temperature. Choosing this temperature instead of the higher conventional temperature (>800℃) effectively inhibits the rapid growth and densification of metallic iron particles, thereby maintaining high porosity at the reaction interface, facilitating continuous hydrogen permeation and the removal of product water vapor. A mixed gas consisting of high-purity green hydrogen and recycled hydrogen-rich reformed gas (H2+CO) is introduced. H2 is responsible for the main reduction reaction (Fe... x O y The diffusion rate of H2 is fast (e.g., +yH2→xFe+yH2O). CO acts as an auxiliary reducing agent, and its reduction is an exothermic reaction that can locally supplement heat. Moreover, the molecular size of CO is slightly larger than that of H2, forming a complementary relationship in microporous diffusion behavior. A high concentration (≥90%) of reducing gas ensures a strong driving force for reduction.

[0042] Soaking Zone: Temperature controlled at 830-870℃. CO gas from the system circulation is introduced, accounting for 12% of the total gas flow in this zone. Raising the temperature to this range aims to thermodynamically promote the complete conversion of the most difficult-to-reduce FeO to Fe, ensuring a high metallization rate of ≥92%. Introducing a small amount of circulating CO adjusts the gas phase composition and slightly reduces the hydrogen partial pressure. This helps suppress the "excessive hydrogen permeation" phenomenon that may occur under a pure hydrogen atmosphere, reducing the dissolved hydrogen content in the product's metallic iron, thereby improving its subsequent processing performance. Simultaneously, at this temperature, the pellets already possess good metallic plasticity, which is beneficial for eliminating internal stress through solid-state diffusion, resulting in a denser, higher-strength pre-reduced product, facilitating hot-loading transportation.

[0043] After reduction, high-temperature pre-reduced pellets with a metallization rate of 94.3% are obtained, with an outlet temperature of approximately 820℃. High-temperature tail gas with a temperature of approximately 900℃ is discharged from the top of the vertical shaft furnace. The high-temperature tail gas contains approximately 45% H2, 15% CO, 20% CO2, 18% H2O, and 2% of other components.

[0044] S3, Exhaust Gas Reforming and Recirculation:

[0045] Dust removal: High-temperature exhaust gas is filtered by high-temperature metal filter bags, reducing dust concentration to <15mg / Nm³. 3 Protect downstream reforming catalysts from dust poisoning and clogging, ensuring their long-term activity.

[0046] Catalytic reforming: After dust removal, the gas enters a fixed-bed reforming reactor packed with Ni / Al2O3 catalyst, where a CO2-H2O co-reforming reaction is carried out at 700℃. The tail gas from the vertical shaft furnace is rich in unreacted H2, products H2O and CO2, as well as some CO. Under the action of the Ni / Fe-based catalyst, the following reactions mainly occur:

[0047] CO2 + H2 CO + H2O (reverse water vapor shift reaction);

[0048] CO + H₂O CO2 + H2 (water vapor shift reaction);

[0049] The two reactions described above are reversible, reaching dynamic equilibrium under suitable catalyst and reaction temperature (600-750℃), effectively converting some CO2 and H2O into CO and H2. If the exhaust gas contains trace amounts of methane (e.g., from a hydrogen source or a side reaction), the following may also occur:

[0050] CH4 + CO2 → 2CO + 2H2 (Methane reforming with carbon dioxide)

[0051] CH4 + H2O → CO + 3H2 (methane steam reforming)

[0052] These reactions further consume CO2 and H2O, increasing the yields of H2 and CO. These reactions occur at the active sites on the catalyst surface, ultimately breaking down and recombining most of the CO2 and H2O molecules in the exhaust gas into useful reducing agent molecules CO and H2. This not only recovers unreacted H2, but more importantly, it converts CO2, which would otherwise need to be captured, stored, or emitted in traditional processes, into valuable chemical feedstock (CO), achieving the recycling of carbon within the system.

[0053] Dehydration: The reformed gas is cooled to 40°C and condensate is removed by a gas-liquid separator, reducing the dew point to <3°C. Dehydration after the reforming reaction prevents condensate from causing corrosion in subsequent pipelines and equipment, and reduces the content of inert components (H2O) in the circulating gas.

[0054] CO2 Removal: After dehydration, the gas enters the Pressure Swing Adsorption (PSA) unit to remove CO2 to a content of <2.5%, yielding hydrogen-rich reformed gas, whose main components are approximately 70% H2, approximately 27% CO, and 3% other components. Removing residual CO2 can further increase the reduction potential of the circulating gas (increasing the effective H2 / CO concentration), resulting in higher quality gas returned to the vertical shaft furnace and improved reduction efficiency.

[0055] Gas distribution: 75% of the total hydrogen-rich reforming gas is returned to the main reduction section of the vertical shaft furnace for circulation; the remaining 25% is stored and prepared for use in electric arc furnace injection. The majority of the gas reuse ensures the main gas source and hydrocarbon circulation for the vertical shaft furnace reduction process; a small portion is led to the electric arc furnace to provide refining medium for the next process, realizing dual use of the gas.

[0056] S4, Electric Arc Furnace Melting:

[0057] Hot charging: High-temperature pre-reduced pellets are protected by N2 (flow rate 500 Nm³).3 The closed conveying system ( / h) is hot-loaded into the electric arc furnace at a temperature of 800℃ and a hot-loading rate of 90%.

[0058] Melting period: Power supply of 12MW, deep arc operation (an operation method in which the electric arc can penetrate deeper into the furnace charge layer and act directly on the molten pool by adjusting the electrode position. This can improve thermal efficiency, shorten melting time, and also help reduce electrode consumption and thermal erosion of the furnace lining), while oxygen is blown in from the bottom of the furnace at a flow rate of 35Nm³ / h.

[0059] Refining phase: Power supply reduced to 8MW. Slagging agents (lime, dolomite) added for slagging. Simultaneously, stored hydrogen-rich reformed gas is pumped at a pressure of 0.7MPa and a flow rate of 25Nm³. 3 / h is injected into the molten pool through the permeable bricks at the bottom of the furnace. The injected room temperature or low temperature gas expands rapidly in the high temperature molten pool, generating a strong pumping effect, promoting the homogenization of temperature and composition within the molten pool, and accelerating the slag-metal interface reaction. The CO component in the injected gas reacts with dissolved oxygen [O] in the molten steel to generate CO2. This is a deoxidation reaction that occurs inside the molten steel, which is more uniform than deoxidation by precipitation (such as adding aluminum), helping to obtain a lower and more uniform final oxygen content and improving the purity of the molten steel. The injected H2 and CO can reduce iron oxide (FeO) in the electric arc furnace slag: (FeO) + H2 → [Fe] + H2O or (FeO) + CO → [Fe] + CO2. This reaction can effectively reduce the TFe content of the final slag (≤8%), recover more iron elements into the molten steel, improve metal recovery, and reduce the corrosivity of the slag.

[0060] Endpoint control: At the end of refining, the carbon content of the molten steel is 0.042%, and the temperature is 1645℃. The TFe content in the final slag is 7.2%, and the binary basicity R is 3.0.

[0061] S5, Waste Heat Recovery

[0062] The 450℃ flue gas discharged from the green hydrogen vertical shaft furnace enters the waste heat boiler, generating 1.8MPa steam to drive a generator. The power generation of this furnace is 115MWh. The flue gas temperature (450-600℃) discharged from the vertical shaft furnace is a medium-low temperature heat source, suitable for generating medium-pressure steam (≥1.6MPa) through the waste heat boiler to drive a steam turbine generator set for power generation. This part of the electricity can be used to power the electric arc furnace or other equipment, and its power generation accounts for about 30%-35% of the power consumption of the electric arc furnace. The high-temperature exhaust gas of about 1300℃ generated by the electric arc furnace can preheat the next batch of composite pellets to above 500℃ through a radiant heat exchanger.

[0063] Example 2:

[0064] This embodiment provides a short-process steelmaking process using an electric arc furnace based on hydrogen-assisted reduction. The method and steps are basically the same as in Embodiment 1, except that:

[0065] S1. When preparing the pellet core, high-grade iron ore powder accounts for 95.5%, Na2CO3 is the reduction promoter, accounting for 0.5%, and bentonite accounts for 4.0%.

[0066] The shell slurry (shell material) is prepared as follows: the carbonaceous material is biochar, with a dry basis of 85%; the porous framework material is porous silica micro powder, with a dry basis of 10%; the alkali metal compound is sodium carbonate, with a dry basis of 0.8%; and the binder is carboxymethyl cellulose, with a dry basis of 4.2%.

[0067] S2, Vertical shaft furnace pre-reduction

[0068] Main reduction section: Total gas flow rate is 80 Nm³ 3 / h·t, pressure 0.3MPa, axial flow velocity controlled at 0.15m / s by gas distribution plate (opening ratio ~60%) inside the furnace.

[0069] S3. Gas distribution in tail gas reforming and circulation: 80% of the total amount of hydrogen-rich reformed gas is returned to the main reduction section of the vertical furnace for circulation; the remaining 20% ​​is stored and prepared for electric furnace injection.

[0070] S4, Electric Arc Furnace Melting:

[0071] Melting period: Power supply 14MW. Refining period: Power supply reduced to 9MW. End point control: At the end of refining, the final carbon content of the molten steel is 0.035%, and the temperature is 1632℃. The final slag contains 7.4% TFe and has a binary basicity R=2.8.

[0072] Example 3:

[0073] This embodiment provides a short-process steelmaking process using an electric arc furnace based on hydrogen-assisted reduction. The method and steps are basically the same as in Embodiment 1, except that:

[0074] S1. When preparing the pellet core, high-grade iron ore powder accounts for 96.5%, CaF2 is the reduction promoter, accounting for 1.5%, and bentonite is the binder, accounting for 2.0%.

[0075] The shell slurry (shell material) is prepared as follows: the carbonaceous material is metallurgical coke powder, accounting for 90% of the dry basis; the porous skeleton material is porous silica micro powder, accounting for 5% of the dry basis; the alkali metal compound is sodium carbonate, accounting for 0.5% of the dry basis; and the binder is carboxymethyl cellulose, accounting for 4.5% of the dry basis.

[0076] S2, Vertical shaft furnace pre-reduction

[0077] Main reduction section: Total gas flow rate is 120 Nm³3 / h·t, pressure 0.5MPa, axial flow velocity controlled at 0.3m / s by gas distribution plate (opening ratio ~60%) inside the furnace.

[0078] S3. Gas distribution in tail gas reforming and circulation: 70% of the total amount of hydrogen-rich reformed gas is returned to the main reduction section of the vertical furnace for circulation; the remaining 30% is stored and prepared for electric furnace injection.

[0079] S4, Electric Arc Furnace Melting:

[0080] Melting period: Power supply 10MW. Refining period: Power supply reduced to 7MW. End point control: At the end of refining, the carbon content of the molten steel is 0.045%, and the temperature is 1648℃. The TFe content in the final slag is 7.6%, and the binary basicity R=3.2.

[0081] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the design concept of the present invention should fall within the protection scope of the present invention.

[0082] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. An electric arc furnace short process steelmaking process based on hydrogen energy assisted reduction, characterized in that, The method comprises the following steps: S1, pellet preparation: mixing high-grade iron ore powder, reduction promoter and binder, granulating to form a pellet core, and wrapping the pellet core with a layer of shell material, and then drying and solidifying to obtain composite pellets with a particle size of 10-15 mm; S2, shaft furnace pre-reduction: sending the composite pellets into a green hydrogen shaft furnace for staged temperature control pre-reduction to obtain high-temperature pre-reduced pellets and high-temperature tail gas; S3, tail gas reforming and recycling: sequentially performing dust removal, catalytic reforming, dehydration and CO2 removal on the high-temperature tail gas to obtain hydrogen-rich reforming gas; S4, electric arc furnace smelting: hot charging the high-temperature pre-reduced pellets into an electric arc furnace for smelting; at the same time, a part of the hydrogen-rich reforming gas is injected into the molten pool of the electric arc furnace; S5, waste heat recovery: recovering the flue gas waste heat of the green hydrogen shaft furnace and the waste gas waste heat of the electric arc furnace for power generation and preheating of the pellets, respectively.

2. The hydrogen energy assisted reduction based EAF mini steelmaking process according to claim 1, characterized in that, In step S1, the total iron mass content TFe of the high-grade iron ore powder is ≥68%; the reduction promoter is CaF2 or Na2CO3, and the mass ratio of the reduction promoter in the pellet core is 0.5%-1.5%; the binder is bentonite, and the mass ratio of the binder in the pellet core is 2-4%.

3. The hydrogen energy assisted reduction based EAF mini steelmaking process according to claim 1, characterized in that, In step S1, the shell material is composed of 80%-90% carbonaceous material, 5-15% porous framework material, 0.5-1% alkali metal compound and 4-4.5% binder, based on the total dry mass of the shell material.

4. The hydrogen energy assisted reduction based EAF mini steelmaking process according to claim 3, characterized in that, The carbonaceous material is metallurgical coke powder or biomass charcoal, the porous framework material is porous silica powder, and the alkali metal compound is potassium carbonate or sodium carbonate.

5. The hydrogen energy-based assisted reduction-based electric arc furnace short- process steelmaking process according to claim 1, characterized in that, In step S2, the staged temperature control pre-reduction method is that the composite pellets are laid with a thickness ≤1.2 m, and a drying section, a main reduction section and a soaking section are sequentially arranged along the downward direction of the material, wherein: The control temperature of the drying section is 440-460℃; The control temperature of the main reduction section is 635-665℃, the reduction gas passed into the main reduction section is mixed gas of high-purity green hydrogen and circulating hydrogen-rich reforming gas, the volume concentration of hydrogen in the mixed gas is ≥90%, the passing flow is 80-120Nm 3 / h·t, the pressure is 0.3-0.5MPa, the axial flow speed is 0.15-0.3m / s, and the mixed gas is uniformly passed in through a porous distribution plate with an open porosity of 60%. The control temperature of the soaking section is 830-870℃, and circulating CO gas is introduced, and the percentage of the circulating CO gas in the total gas volume of the section is ≤15%.

6. The hydrogen energy-based assisted reduction-based electric arc furnace short- process steelmaking process according to claim 5, characterized in that, In step S3, the catalytic reforming is a CO2-H2O co-reforming reaction in a reforming reactor, the catalyst is a Ni-based catalyst, the reaction temperature is 600-750℃, and after reforming, 70%-80% of the hydrogen-rich reforming gas is returned to the main reduction section of the green hydrogen shaft furnace, and 20%-30% of the hydrogen-rich reforming gas is distributed for injection into the electric arc furnace molten pool.

7. The hydrogen energy-based assisted reduction-based electric arc furnace short- process steelmaking process according to claim 1, characterized in that, In step S4, the hot charging temperature of the high-temperature pre-reduced pellets is ≥750℃, and the electric arc furnace smelting process includes a melting period and a refining period, wherein: The power supply power during the melting period is 10-14 MW, and deep arc operation is performed through the electrode, and oxygen is blown from the bottom to assist melting; The power supply power during the refining period is reduced to 7-9 MW, and a slagging agent is added for slagging, the slag thickness is controlled to be 100-120 mm, the final carbon content is controlled to be 0.03-0.05%, the final temperature is 1630-1650℃, the control final slag binary basicity R is 2.8-3.2, and the TFe content in the final slag is ≤8%.

8. The hydrogen energy-based assisted reduction-based electric arc furnace short- process steelmaking process according to claim 1, characterized in that, In step S5, the flue gas waste heat is used to generate steam with a pressure ≥1.6 MPa through a waste heat boiler for power generation, and the waste gas waste heat is used to preheat the pellets to be charged into the furnace to a temperature above 500℃.

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