New process for smelting hot and cold metal feedstock mixtures producing reduced carbon emissions

Abstract

The invention relates to a method for smelting a metal-containing feedstock. More specifically, the present invention relates to a process for smelting hot and cold metal-containing feedstock mixtures that produce significantly reduced carbon emissions. According to a first aspect of the present invention, there is provided a method of smelting a metal-containing feedstock, the method comprising the steps of: (i) feeding a composition of hot and cold metal-containing feedstocks, a reducing agent, and a fluxing agent into an open furnace (OBF) through a plurality of adjustable feed chutes, wherein the OBF can operate in an open arc mode (short open arc and long open arc control modes), a brush arc mode and a submerged arc mode; (ii) heating the hot and cold metal-containing feedstock, reducing agent and fluxing agent in an OBF at a temperature of 1400 DEG C to 1800 DEG C, sufficiently smelting the feedstock, reducing agent and fluxing agent, thereby forming a liquid metal product, a liquid slag product and a CO-containing gas; (iii) carburizing the metal product by introducing a carbon source into the OBF; and (iv) ensuring that a composition of hot and cold metal-containing feedstocks, a reducing agent and a fluxing agent are continuously fed into the OBF through the adjustable feed chute to optimize the power-feed balance; wherein the carbon content of the liquid metal product is higher than 4.0% (m / m%), and the silicon content is lower than 1.5% (m / m%).

Description

Technical Field

[0001] This invention relates to a method for smelting metallic raw materials. More specifically, this invention relates to a method for smelting a mixture of hot and cold metallic raw materials that produces significantly reduced carbon emissions. Background Technology

[0002] In the prior art, electric arc furnaces (EAFs) are typically used to smelt direct reduced iron (DRI). Due to the use of highly conductive scrap steel and DRI, foamy slag is added to cover the electric arc.

[0003] In this regard, US 5,611,838 discloses a method that involves smelting scrap and DRI steel in an open-bath direct-current furnace using foamed slag and hollow electrodes. This method uses lances to inject oxygen through the furnace shell. However, this method cannot feed low-grade materials into the EAF, resulting in low recovery of the target metal and excessive slag production due to the oxidizing environment formed within the EAF.

[0004] WO 99 / 36581 discloses a dual-furnace system comprising a kiln for preliminary reduction of ore and an EAF for subsequent smelting, designed to optimize the interaction between pre-reduction and smelting. The aforementioned disclosure addresses the pre-reduction stage by employing a rotary hearth furnace, allowing pre-reduction and smelting to occur in two separate processing units. The system includes transferring pellets containing ore and reducing agent from the pre-reduction furnace to the smelting furnace. Furthermore, a connecting shell is provided for connecting the two processing units. However, using two separate units for pre-reduction and smelting adversely affects energy retention in the process. Therefore, more electrical energy needs to be input into the smelting furnace, leading to higher operating costs, reduced efficiency, and negative environmental impacts.

[0005] US2021 / 301359 addresses the integration of the Direct Reduced Iron (DRI) melting step with the DRI production step. Similar to WO99 / 36581, it teaches two distinct processing units for reduction and melting, consisting of a DRI melting furnace and a direct reduction vertical furnace. A discharge chute connects the discharge outlet of the vertical furnace to the inlet of the DRI furnace. This chute simultaneously supplies DRI and reducing gas from the vertical furnace, where the reducing gas plays a crucial role in controlling the furnace atmosphere to maintain a reducing environment. Notably, the reducing gas is generated from the upstream process and then introduced into the EAF. Furthermore, the document teaches the use of screw feeders or rotary feeders to regulate the feed rate of DRI into the furnace, which accepts high-grade raw materials. A throttling feed-discharge method is also employed to form piles according to the angle of repose within the DRI furnace.

[0006] WO2023 / 281153 teaches an iron processing method in which reducing gas from a DRI unit is introduced into an EAF to control the furnace atmosphere. This method focuses on first reducing phosphorus content and desulfurizing before introducing the intermediate iron product into the steel conversion unit. Although this method produces a high-carbon product, the 1%–4% high carbon content in the final product is often accompanied by a high silicon content, making the final product less than ideal, as it can be considered a cold stock. Due to the low temperature and high silicon content of the final product, downstream processes must provide additional energy and / or perform refining to further process the product obtained from the furnace. Therefore, it is necessary to minimize the silicon content in the final product to facilitate downstream processes.

[0007] Most notably, the methods in US5,611,838, WO99 / 36581, and US2021 / 301359 all employ an Exhaust Flame Furnace (EAF) to complete the smelting process. Most notably, EAFs operate in an oxidizing environment and utilize foamed slag to achieve the reduction of direct reduced iron, which naturally means that some target metals exist in the form of oxides. Furthermore, EAFs are suitable for intermittent operation, requiring regular replacement of the furnace lining refractory material, often leading to production interruptions, frequent maintenance, and increased maintenance costs. Another drawback of EAFs is that they can only accept high-grade feedstock. When low-grade feedstock is added to an EAF, excessive slag products are generated, resulting in low recovery rates, making EAFs unsuitable for situations with inconsistent feedstock quality.

[0008] Therefore, known process routes, when using low-grade raw materials, neither demonstrate high output efficiency nor achieve reduced carbon emissions. Given these challenges, there is an urgent need for innovative smelting technologies that can efficiently process a wider range of material qualities, reduce environmental footprint, decrease reliance on downstream processing, and operate continuously.

[0009] For the purposes of this specification, it should be understood that the following acronyms are synonymous with the phrases referenced below.

[0010] Purpose of the invention Therefore, the object of the present invention is to provide a novel method for smelting hot and cold metal-containing raw material mixtures that at least partially overcomes the aforementioned disadvantages and limitations, and / or provides a useful alternative to the prior art, thereby providing high-quality products that are more favorable to downstream processes when using low-grade raw materials, with a significantly lower carbon footprint and specific energy requirement. Summary of the Invention

[0011] According to a first aspect of the present invention, a method for smelting a metal-containing raw material is provided, the method comprising the following steps: (i) A combination of hot and cold metal-containing raw materials, reducing agents and fluxes are supplied to an open furnace (OBF) through multiple adjustable feed troughs, wherein the OBF can operate in open arc mode (short open arc and long open arc control mode), brush arc mode and immersed arc mode. (ii) At a temperature of 1400℃-1800℃, hot and cold metal-containing raw materials, reducing agents and fluxes are heated in OBF to fully melt the raw materials, reducing agents and fluxes, thereby forming liquid metal products, liquid slag products and CO-containing gas; (iii) Carburizing of metal products by introducing a carbon source into the OBF; and (iv) Ensure that hot and cold metal-containing raw material compositions, reducing agents and fluxes are continuously supplied to the OBF through an adjustable feed trough to optimize power-to-feed balance. The liquid metal product has a carbon content higher than 4.0% (m / m%) and a silicon content lower than 1.5% (m / m%).

[0012] The metal-containing raw material described in this invention is an iron-containing raw material.

[0013] In this article, "smelting" should be understood as the process of extracting iron from iron-containing raw materials. It should be understood that the iron-containing raw material can be any material, such as ore, concentrate, waste, powder, waste generated from the steel production value chain, or any combination of these materials, wherein the material or combination of the materials contains metallic iron (Fe) or compounds containing metallic iron (Fe).

[0014] Iron-containing raw materials can be pre-reduced iron raw materials or unreduced iron raw materials.

[0015] The pre-reduced iron-containing raw material described in this invention is pre-reduced iron ore.

[0016] Similarly, the unreduced iron raw material described in this invention is unreduced iron ore.

[0017] The pre-reduced iron ore can be hot-brquetted iron (HBI) or cold-reduced iron (CDRI). The HBI can be pulverized HBI (HBI < 20 mm). Iron-containing raw materials may include cold-pressed iron scrap (CBI<20mm).

[0018] Iron-containing raw materials may include scrap iron powder (<20 mm), iron oxide scale (mill scale) (<10 mm), pre-reduced iron ore powder (<10 mm), unreduced iron ore powder (<10 mm), and combinations thereof.

[0019] In embodiments of the present invention, the pre-reduced iron ore may be carbon-deficient or carbon-free HBI or CDRI. It should be understood that the pre-reduced iron ore may be low-iron HBI or CDRI. In another embodiment of the invention, the pre-reduced iron ore may include recycled waste.

[0020] The present invention also provides an iron-containing raw material composed of 100% 50 μm iron ore particles.

[0021] The present invention provides multiple adjustable feed troughs, which enable the introduction of a combination of hot and cold iron-containing raw material mixtures into the OBF.

[0022] Multiple adjustable feed troughs allow for the addition of hot and cold iron-containing raw material mixtures around the outer perimeter of the OBF inner wall or around at least one electrode of the OBF.

[0023] This invention can also use 100% hydrogen to produce low-grade HBI or cold DRI to further reduce the CO2 footprint. It should be understood that HBI or CDRI produced using 100% hydrogen has extremely low or even 0% carbon content.

[0024] This invention continuously replenishes the OBF with iron-containing raw materials, reducing agents, and fluxes through multiple adjustable feed troughs, thereby ensuring optimized weight loss and power-feed balance.

[0025] The specific energy requirement (SER) of a smelting process can be simply expressed as the ratio of MWh or power (MW) consumed per metric ton of total feed to the feed rate (tons / h). SER refers to the energy required to convert a 25°C feed into a product stream at the temperature required to exit the furnace. Therefore, SER is essentially a power-feed ratio. It should be understood that if the chemical composition or temperature of the feed deviates from the theoretical baseline, the theoretical SER will change significantly. According to the present invention, the power capacity of the DC furnace is up to 100MW, typically 400-700kWh / ton of molten metal, and the typical amount of reducing agent is 45-50kg / ton of molten metal, so that the carbon content of the produced liquid metal product is higher than 4.0%.

[0026] In embodiments of the present invention, the temperature of the liquid metal product can be 1330℃-1550℃.

[0027] In an embodiment of the present invention, the OBF can be a DC OBF (DC furnace).

[0028] In embodiments of the present invention, the DC furnace includes an insulated copper or steel furnace top.

[0029] In an embodiment of the present invention, the DC furnace consists of at least one electrode.

[0030] As described above, the DC furnace comprises multiple adjustable feed troughs, which allow a mixture of hot and cold iron-containing raw materials to be introduced into the DC furnace. These feed troughs may include a single feeder connected to each feed trough. The DC furnace may include any number of feed troughs, but in particular, the DC furnace includes 4 or 8 feed troughs. In another preferred embodiment, the DC furnace may include 6 or 12 feed troughs.

[0031] The reducing agent described in this invention can be a low-grade reducing agent, such as anthracite, fine-fraction coke, or petroleum coke. In embodiments of this invention, the reducing agent can be biochar. The reducing agent can be added to OBF in granular form, with a particle size equal to or less than 0-50 mm.

[0032] Fluxes can be selected from calcined dolomite, calcined limestone, quartzite, bauxite, and combinations thereof.

[0033] In this invention, liquid metal product materials can be formed by heating and melting, or at least partially melting, iron-containing raw materials, reducing agents and fluxing agents.

[0034] The residence time of iron-containing raw materials in OBF can be controlled to control the degree of reduction of iron-containing raw materials in OBF.

[0035] According to the present invention, the slag product can be used in downstream applications such as cement.

[0036] In the method, the degree of iron metallization in the iron-containing raw material can be as low as 86% to 94%.

[0037] It should be understood that carburizing involves taking a low-carbon metal product and converting it into a high-carbon metal product. This can be accomplished by exposing the metal product to a carbon-rich atmosphere. By heating the metal product in a carbon-rich atmosphere, carbon atoms are deposited on the surface of the metal product at the molecular level. According to the invention, carburizing can be achieved by injecting carbon into molten metal in a DC (discharge vessel). In an alternative embodiment of the invention, carburizing can be carried out in a torpedo, a hot metal ladles, or a suitable type of container.

[0038] In embodiments of the present invention, if desired, the DC furnace may include a carbon lance to introduce carbon into the DC furnace, thereby promoting carburization of the metal product.

[0039] It should be understood that by using carbon injection, the liquid metal product can be enriched with carbon, exceeding the carbon content level that is considered achievable according to the material balance of this method. From a material balance perspective, achieving a high carbon content above 4.0% in the liquid metal product often inevitably increases the content of impurities (such as silicon), which in turn adversely affects the high temperature of the liquid metal product, thereby impacting downstream processing.

[0040] It should also be understood that, since carburizing liquid metal products via carbon implantation allows for the use of less reducing agent in hot and cold iron-containing feedstock mixtures, it has now been unexpectedly found that lower silicon content can be obtained in liquid metal products than when carbon implantation is not used.

[0041] Liquid metal products have the following characteristic values:

[0042] This invention provides a multiphysics computational fluid dynamics model for the reaction, dynamics, and different conversion modes of a DC furnace.

[0043] It should be understood that the operations after exiting the furnace can be seamlessly integrated into the method of this invention. In view of the foregoing, it should be understood that by taking into account, in particular, the target parameters of the method (as described in the specific implementation below), including lower specific energy requirements and the ability to operate the OBF at higher energy inputs (increased power density), it is possible to achieve less greenhouse gas emissions, thereby reducing the net carbon footprint of the method to 20%-40% of that of the conventional BF route.

[0044] It should be understood that the steps of the method according to the invention do not necessarily have to be performed in sequence, as the method can be operated in an intermittent, semi-intermittent, or continuous manner. Furthermore, it is conceivable that the steps of the provided method do not necessarily need to be performed in the order listed herein. Attached Figure Description

[0045] The invention will now be further described by way of example with reference to the accompanying drawings, in which: Figure 1 This is a schematic diagram of a method for melting hot and cold metal-containing raw material mixtures according to the present invention; Figure 2 for Figure 1 A front cross-sectional view of the adjustable feed trough used in one embodiment of the method shown; Figure 3 for Figure 1 A front perspective view of the electrode arm assembly in the DC furnace used in the method shown; Figure 4 for Figure 1 A front view of the copper furnace top design used in a preferred embodiment of the DC furnace in the method shown; Figure 5 for Figure 1 A top view of a preferred embodiment of the OBF in the method shown, illustrating the arrangement of 12 feed troughs; and Figure 6 The illustration depicts Figure 1 A schematic diagram of the arc zone in the method shown. Detailed Implementation

[0046] The scope of the invention described herein is not limited to any specific embodiments or examples disclosed herein, as these embodiments or examples are intended to illustrate some aspects of the invention. Any equivalent embodiments should be considered within the scope of protection of the invention, as these equivalent embodiments will be readily apparent to those skilled in the art from the description herein.

[0047] test To illustrate the effectiveness of the working embodiment of the present invention, a 1 MW pilot-scale DC furnace according to the first aspect of the present invention was constructed, which can be industrially scaled up.

[0048] A total of 443 tons of natural gas (NG) was used to reduce DRI in 146 batches of materials, producing 127 slag heaps and 146 liquid metal product releases, with a total liquid metal product yield of 334 tons.

[0049] During the testing process, parameters such as the method's SER, liquid slag parameters, liquid metal product parameters, the effect of carbon lance carburizing on liquid metal products, scaling the furnace power density to reduce furnace size, and the effect of different refractory materials were evaluated, as well as the effects of combining different feeding methods with different OBF current settings (collectively referred to as "operating modes"). The test operation mode is as follows: 1. Short Open Arc Control (SOAC) operation, with feed distributed around the electrode periphery; 2. Short Opening Arc Control (SOAC) operation, with feed distributed around the perimeter of the furnace sidewall; 3. Arc brushing operation, with the feed material distributed around the electrode periphery; 4. Arc brushing operation, with the feed material distributed around the outer perimeter of the furnace sidewall; and 5. Immersion electrode operation, with the feed distributed around the outer perimeter of the furnace sidewall.

[0050] It should be understood that the present invention is not limited to the above-described operating modes, which are merely illustrative of the present invention.

[0051] Following the heating and stabilization phases, a total of seven test conditions were performed to verify the above parameters:

[0052] result: A high level of iron reduction was achieved, resulting in a low iron content (<1%) in the slag. The temperature difference between the liquid metal product and the liquid slag at the tapping point was only occasionally observed and was significantly affected by the carbon balance of the OBF (On-Balance Furnace). This, in turn, means that slag temperatures exceeding the limit of 1550°C may occur in commercial OBFs.

[0053] Because of the high level of superheat in the molten products and the relatively small reduction smelting volume compared to ferroalloy furnaces, this furnace can continue to operate and discharge even in a state of carbon excess. In contrast, the situation is significantly different if ferroalloys such as ferrochrome are being smelted. Both the metallic products and slag are highly likely to solidify at the discharge port, thus preventing discharge. This highlights the specific operational tolerances and challenges associated with different types of smelting methods and furnace conditions.

[0054] Liquid slag products The control of the composition of liquid slag products is affected by the following key factors: 1) As mentioned above, there is a delay between fluctuations in the carbon (C) and silicon (Si) content of liquid metal products and changes in furnace input parameters and their resulting effects.

[0055] 2) Natural variations in the chemical composition of direct reduced iron (DRI), particularly the carbon content.

[0056] 3) The slag and metal yields in the method are low, which means that even a very small change in the DRI composition (e.g., a change of 0.5% absolute value) can have a significant impact, and may even cause the slag composition to change by more than 2.5%.

[0057] Despite these influencing factors, there are still cases where the temperature of the liquid metal product and the composition of the liquid slag product meet the target specifications, even with fluctuations in the DRI composition. Table 1 below shows the target slag parameters.

[0058] Table 1: Target Slag Parameters

[0059] Liquid metal products Without using a carburizing agent injected into the liquid metal product via a spray gun system, an average carbon (C) content of 4.06% and a silicon (Si) content of 1.32% were successfully achieved in the liquid metal product. This was achieved by maintaining a high level of reducing agent in the furnace feed (up to 8 kg of reducing agent per 100 kg DRI). Furthermore, the average molten metal temperature recorded was 1381°C, lower than the target temperature of 1450°C.

[0060] Importantly, it should be recognized that the low metal temperature is primarily due to thermodynamic limitations, achieved by maintaining a high excess carbon level in the feed, allowing the carbon threshold to exceed 4.0%. This condition promotes significant silicon reduction into the liquid metal product. It has also been observed that prolonged overcarbonization leads to severe buildup on the sidewalls, resulting in a reduction in the crucible size of the OBF, making this operating condition unsustainable in the long term.

[0061] Surprisingly, however, by reducing the amount of reducing agent supplied to the furnace (3.5-4.5 kg / 100 kgDRI), lower carbon and silicon contents and higher liquid metal product exit temperatures were unexpectedly achieved. The results obtained by supplying less reducing agent are shown in Table 2 below.

[0062] Table 2: Analysis of liquid metal products supplied to OBF (3.5-4.5 kg / 100 kg DRI)

[0063] By using a pneumatic method to inject the carburizing agent of the liquid metal product through a carbon spray gun with a heat-resistant lining, according to row 5 of Table 2 above, unexpectedly, a liquid metal product with lower silicon content, higher carbon content, and higher furnace exit temperature was obtained.

[0064] Operating mode The composition of the liquid metal product is moderately influenced by the operating mode itself. However, this influence is masked by the effects of the furnace reducing agent (carbon) and the balance between feed and power. Furthermore, sidewall feeding plays a crucial role in controlling the formation of the protective sidewall deposit. Despite its advantages, this method occasionally results in some raw materials being discharged from both the liquid slag product and the liquid metal product outlet.

[0065] Furthermore, pneumatically injected carburizing materials have been shown to not only enhance the carburization of liquid metal products but also improve heat transfer from liquid slag products to liquid metal products. This is mainly attributed to the mixing effect caused by bubbling gas, which helps the liquid metal products reach a better tapping temperature.

[0066] Experimental conclusions The SER (Sequential Energy Flow) of this method was measured and found to be within the design margin range set by the SER target value of 465-550 kWh / ton of molten metal. Slag production was also controlled within the established target parameters. Effective and precise control of slag chemical composition and furnace carbon balance are extremely important considerations for achieving the target values. Furthermore, accurate and continuous monitoring of DRI (Distilled Intake) composition is crucial, as even small fluctuations in ore type and carbon content can significantly affect the chemical composition of the molten slag products and the overall carbon balance.

[0067] Liquid metal products are also produced within the target performance parameters. In-situ carbon injection systems are considered to play a fundamental and crucial role in achieving these objectives, particularly regarding the carbon content and temperature of the liquid metal products.

[0068] Different operating modes of the OBF were evaluated. Preferably, the OBF operates primarily at full power in brush arc or SOAC mode, while submerged arc operation is feasible only at lower power levels (which may be necessary). The design hearth power density for a commercial-scale OBF is set at 220 kW / m². 2 It has been proven to be an acceptable and safe level.

[0069] In-situ testing of carburizing of liquid metal products using a pneumatic injection lance system demonstrated significant operational benefits, as discussed above regarding achieving the target parameters. The OBF was also operated at high power levels to test the feasibility of future reductions in OBF furnace size, and results showed that increasing power density can reduce OBF size and associated capital expenditure.

[0070] In the accompanying drawings, the method for melting hot and cold metal-containing raw material mixtures according to the present invention is generally indicated by reference numeral 10.

[0071] Figure 1A schematic diagram of a method 10 for melting a hot and cold mixture of metal-containing raw materials according to the present invention is shown. like Figure 1 As shown, HBI, CDRI, waste and powder 20, reducing agent and flux 30 are fed through an adjustable feed trough 40. Figure 2 The hot and cold raw materials 20, as well as the reducing agent and flux 30 (where applicable), are fed into the DCF 50 in batches in different hoppers and proportionally distributed in the adjustable feed trough 40 (see [link to relevant documentation]). Figure 5 The weight loss and feed-power ratio system controls the furnace feeds 20 and 30, which can be fed into the center (hollow electrode) of DCF 50, the periphery of DCF 50 (side feed), or the high-intensity energy zone of DCF 50 (near the electrode).

[0072] The high airflow velocity around the DCF 50 plasma (not shown) draws materials 20 and 30 into the arc region. Figure 6 The DCF50 can use single or multiple graphite electrodes. Figure 3 The furnace is operated. The operation control of the furnace is achieved through a dedicated furnace control system (not shown) and the high stability of furnace operation with electrode ends (not shown). The control system is a combination of electrode current control, furnace impedance control, furnace resistance control, furnace power input and rectification control. The DCF 50 has a power capacity of up to 100 MW, typically 400-700 kWh / ton of molten metal, and a typical amount of reducing agent of 45-50 kg / ton of pig iron (target 0.1%C-4.5%C).

[0073] Furnace 50 itself is constructed of a steel outer shell and equipped with a refractory-based enclosure system, capable of safely containing molten material at temperatures up to 1800°C. Furnace 50 includes an insulated copper or steel roof. Figure 4 ).

[0074] Molten metal 60 (see Table 2 above) and molten slag 70 (see Table 1 above) are intermittently discharged from DCF 50 and conveyed to downstream processes for the production of steel (from molten metal 60) and cement substitutes (from slag 70). Depending on the plant's needs, molten metal 60 is discharged from a set of dedicated, uniquely positioned metal and slag outlets (not shown). The DCF50 is equipped with carbon lances 80, which can be strategically positioned to optimize the carbon supply location for hot iron carburizing if needed. Additional carburizing can also be accomplished by adding carbon to the torpedo.

[0075] The net carbon footprint of this production method 10 is estimated to be 20%-40% of that of the conventional BF route.

[0076] Meanwhile, Method 10 provides an improved alternative to the prior art, which can use a mixture of cold and hot low-grade feedstocks while exhibiting a significantly lower carbon footprint and high-efficiency output.

[0077] This specification is presented by way of example only and is intended to provide the most practical and easily understood description of the principles and concepts of the invention. In this respect, no attempt is made to show structural details of the invention and / or the devices used therein, except as necessary for a basic understanding of the invention.

Claims

1. A method for smelting metal-containing raw materials, the method comprising the following steps: (i) A combination of hot and cold metal-containing raw materials, reducing agent and flux is supplied to an open furnace (OBF) through multiple adjustable feed troughs, wherein the OBF can operate in open arc mode (short open arc and long open arc control mode), brush arc mode and submerged arc mode. (ii) At a temperature of 1400℃-1800℃, hot and cold metal-containing raw materials, reducing agents and fluxes are heated in OBF to fully melt the raw materials, reducing agents and fluxes, thereby forming liquid metal products, liquid slag products and CO-containing gas; (iii) Carburizing of metal products by introducing a carbon source into the OBF; and (iv) Ensure that the hot and cold metal-containing raw material composition, reducing agent and flux are continuously supplied to the OBF through an adjustable feed chute to optimize the power-feed balance; The liquid metal product has a carbon content higher than 4.0% (m / m%) and a silicon content lower than 1.5% (m / m%).

2. The method according to claim 1, wherein, The metal-containing raw material is an iron-containing raw material.

3. The method according to claim 1, wherein, The iron-containing raw material is any material, such as ore, concentrate, waste, powder, waste generated from the steel production value chain, or any combination of these materials, wherein the material or combination of materials contains metallic iron (Fe) or compounds containing metallic iron (Fe).

4. The method according to any one of claims 1-3, wherein, The iron-containing raw material is a pre-reduced iron raw material.

5. The method according to claim 4, wherein, The pre-reduced iron raw material is pre-reduced iron ore.

6. The method according to any one of claims 1-3, wherein, The iron-containing raw material is unreduced iron.

7. The method according to claim 6, wherein, The unreduced iron raw material is unreduced iron ore.

8. The method according to claim 5, wherein, The pre-reduced iron ore is hot-pressed iron (HBI) or cold-pressed iron (CDRI).

9. The method according to claim 8, wherein, The HBI is pulverized HBI (HBI < 20 mm).

10. The method according to any one of claims 1-3, wherein, The iron-containing raw materials include cold-pressed iron scrap (CBI < 20 mm).

11. The method according to any one of claims 1-3, wherein, The iron-containing raw materials include scrap iron powder (<20 mm), iron oxide scale (<10 mm), pre-reduced iron ore powder (<10 mm), unreduced iron ore powder (<10 mm), and combinations thereof.

12. The method according to claim 5, wherein, The pre-reduced iron ore is carbon-deficient or carbon-free HBI or CDRI.

13. The method according to claim 5, wherein, The pre-reduced iron ore is low-iron grade HBI or CDRI.

14. The method according to claim 12 or 13, wherein, The pre-reduced iron ore includes recycled waste.

15. The method according to claim 1, wherein, The temperature of the liquid metal product is 1330℃-1550℃.

16. The method according to claim 1 or 15, wherein, The liquid metal product has the following characteristic values: 。 17. The method according to claim 1, wherein, The OBF furnace has a power capacity of up to 100MW, typically 400-700kWh / ton of molten metal, and a typical amount of reducing agent of 45-50kg / ton of molten metal to ensure that the carbon content of the produced liquid metal product is higher than 4.0%.

18. The method according to any one of the preceding claims, wherein, The method continuously replenishes iron-containing raw materials, reducing agents, and fluxes into the electric furnace through multiple adjustable feed troughs to ensure optimized weight loss and power-feed balance.

19. The method according to claim 1, wherein, The reducing agent is a low-grade reducing agent, such as anthracite, fine-grained coke, or petroleum coke.

20. The method according to claim 1, wherein, The flux is selected from the group consisting of calcined dolomite, calcined limestone, quartzite, bauxite, and one or more combinations thereof.

21. The method according to any one of the preceding claims, wherein, In the method described, the degree of iron metallization in the iron-containing raw materials is as low as 86%-94%.

22. The method according to claim 1, wherein, The carburizing is achieved by injecting carbon into the molten metal in the OBF.

23. The method according to claim 22, wherein, The carburizing is carried out in the torpedo.

24. The method according to any one of the preceding claims, wherein, The net carbon footprint is 20%-40% of that of the traditional BF route.

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