Novel process for smelting metal feedstocks 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 method of smelting a metal-containing feedstock that yields significantly reduced carbon emissions. According to the present invention there is provided a method of smelting a metal-containing feedstock, the method comprising the steps of: (i) feeding the metal-containing feedstock, a reducing agent and a fluxing agent into an open furnace (OBF) by feeding the metal-containing feedstock from the periphery to the side wall or from the periphery to the electrode, wherein the OBF is operable in an open arc mode (short open arc and long open arc control mode), a brush arc mode, and a submerged arc mode wherein at least one stack arrangement is formed during feeding from the periphery to the sidewall; (ii) heating the metal-containing feedstock in an OBF at a temperature of 1400-1800 DEG C to sufficiently melt the metal-containing feedstock, 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 continuous supply of the metal-containing feedstock, reducing agent and fluxing agent into the OBF to maintain at least one stack arrangement formed during the supply from the periphery to the sidewall; 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 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 new method for smelting metal-containing raw materials, which at least partially overcomes the above-mentioned disadvantages and limitations, and / or provides a useful alternative to the prior art, thereby significantly reducing the carbon footprint and achieving high-efficiency output when using low-grade raw materials. 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) The metal-containing raw material, reducing agent and fluxes are supplied to an open furnace (OBF) by supplying the metal-containing raw material from the periphery to the sidewall or from the periphery to the electrode, wherein the OBF can operate in an open arc mode (short open arc and long open arc control mode), a brush arc mode and an immersed arc mode, wherein at least one material pile arrangement is formed during the supply process from the periphery to the sidewall; (ii) At a temperature of 1400℃-1800℃, the metal-containing raw material is heated in OBF to fully melt the metal-containing raw material, thereby forming liquid metal product, liquid slag product and CO-containing gas; (iii) Carburizing of metal products by introducing a carbon source into the OBF; and (iv) Ensure a continuous supply of metallic raw materials, reducing agents and fluxes to the OBF to maintain at least one stockpile arrangement formed during the supply process from the periphery to the sidewalls; 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. In this article, "material pile" should be understood as an assembly formed by stacking one material on top of another material, and stacking them substantially vertically.

[0014] It should be understood that the iron-containing raw material can be any material, such as ore, waste, concentrate, or any combination of these materials, and the material or combination of the materials contains metallic iron (Fe) or compounds containing metallic iron (Fe).

[0015] Iron-containing raw materials can be pre-reduced iron raw materials.

[0016] The pre-reduced iron raw material described in this invention is pre-reduced iron ore.

[0017] The pre-reduced iron ore can be selected from the group consisting of hot briquetted iron (HBI), cold DRI (CDRI), and hot DRI (HDRI).

[0018] In embodiments of the present invention, the pre-reduced iron ore may be carbon-deficient or carbon-free HBI, CDRI, or HDRI. It should be understood that the pre-reduced iron ore may be low-iron grade HBI, CDRI, or HDRI.

[0019] In other embodiments of the invention, the pre-reduced iron ore may include recycled waste.

[0020] This invention can also use 100% hydrogen to produce low-grade HBI, cold DRI, or hot DRI, thereby further reducing the CO2 footprint. It should be understood that HBI or DRI produced using 100% hydrogen has extremely low, or even 0%, carbon content.

[0021] It should be understood that when HDRI is unavailable, the present invention may preheat HBI and CDRI in an inert atmosphere before supplying them to OBF. Therefore, in embodiments of the present invention, the OBF may include a preheating system to preheat the HBI or CDRI to the temperature required to supply the OBF, thereby improving energy efficiency.

[0022] This invention achieves continuous replenishment of iron-containing raw materials, reducing agents, and fluxes by selecting to supply iron-containing raw materials to the OBF from the periphery to the sidewall or from the periphery to the electrode, thereby ensuring that weight loss and power-to-feed balance are optimized.

[0023] The iron-containing material can be supplied from the periphery to the sidewall or from the periphery to the electrode, so that the iron-containing material can be added around the periphery of the inner wall of the OBF or around at least one electrode of the OBF.

[0024] It should be understood that weight loss and power-feed balance are indispensable in this paper.

[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. In this invention, the power capacity of the OBF is up to 120MW, typically 400-700 kWh / ton of molten metal, and the typical amount of reducing agent is 40-60 kg / ton of molten metal, resulting in a carbon content of the produced liquid metal product 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 an AC OBF (AC furnace).

[0028] In this invention, the OBF can be a circular furnace. In another embodiment of this invention, the OBF can be a rectangular furnace.

[0029] It should be understood that if the grade of the metal-containing raw material is lower than that of the blast furnace pellets, the SER may be higher than the above values.

[0030] The reducing agent described in this invention can be a low-grade reducing agent, such as anthracite, fine-fractionated coke, or petroleum coke. The reducing agent can be added to OBF in granular form, with a particle size equal to or less than 0-50 mm.

[0031] The flux can be selected from calcined dolomite, calcined limestone, quartzite, bauxite, and combinations thereof.

[0032] 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.

[0033] 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.

[0034] Before feeding the iron-containing raw material into the OBF, a granulation step can be performed first. Granulation can be completed in a granulation device.

[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 metallization of iron in the iron-containing raw material can be 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.

[0038] According to the present invention, carburizing can be achieved by injecting carbon into molten metal in an OBF.

[0039] In an alternative embodiment of the invention, carburizing can be carried out in a torpedo or a suitable type of container.

[0040] In embodiments of the present invention, if desired, the OBF may include a carbon spray gun to introduce carbon into the OBF, thereby promoting carburization of the metal product.

[0041] 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.

[0042] It should also be understood that, since carburizing liquid metal products through carbon implantation reduces the amount of reducing agent required, it has now been unexpectedly found that lower silicon content can be obtained in liquid metal products than when carbon implantation is not used.

[0043] Liquid metal products are characterized by their chemical similarity to typical molten metal from a blast furnace. Liquid metal products have the following characteristic values: .

[0044] This invention provides a multiphysics computational fluid dynamics model for the reaction, dynamics, and different conversion modes of OBF.

[0045] 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.

[0046] It should be understood that the steps of the method according to the invention do not necessarily have to be performed sequentially, 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

[0047] 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 the method for smelting metal-containing raw materials according to the present invention; Figure 2 for Figure 1 A front perspective view of the six rectangular electrodes arranged in a straight line within the OBF used in one embodiment of the method shown. Figure 3 for Figure 2 A front perspective view of the furnace charge stack arrangement with six rectangular electrodes arranged in a straight line inside the OBF used in the method shown. Figure 4 for Figure 1 A front view of the OBF internal circular three-electrode furnace feeding system used in one embodiment of the method shown; Figure 5 for Figure 4 A top view of the OBF inner circular three-electrode stack arrangement used in the method shown; Figure 6 The top view shows the operating modes of different embodiments of the OBF of the present invention (submerged arc-open pool; submerged arc-open pool; open / brushed arc-reduced open pool; brushed arc-reduced open pool; and shielded arc-bath-covered pool). Figure 7(a) is a schematic diagram of the feed stack relative to OBF vs SAF during DRI melting in submerged arc operation (where the electrodes are immersed); Figure 7(b) is a schematic diagram of the feed stack related to OBF vs SAF during DRI melting, wherein the transfer is configured to switch the operation from submerged arc operation to brush arc operation when the conductive HDRI contacts the electrode; Figure 7(c) is a schematic diagram of the feed stack related to OBF vs SAF during DRI melting in brush arc operation, at which point the electrode is just above or flush with the molten material; Figure 7(d) is a schematic diagram of the feed pile relative to OBF vs SAF during DRI melting in open-arc operation, where the electrode is not in contact with the slag pool or material pile; and Figure 8 This is a schematic diagram of the carbon injection gun used in the method according to the present invention. Detailed Implementation

[0048] 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.

[0049] test To illustrate the effectiveness of the working embodiment of the present invention, a 1 MW pilot-scale DC furnace was constructed, wherein the furnace is equivalent to 1 / 6 of a 6-electrode linearly arranged rectangular OBF.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] Following the heating and stabilization phases, a total of seven test conditions were performed to verify the above parameters:

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 2) Natural variations in the chemical composition of direct reduced iron (DRI), particularly the carbon content.

[0058] 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%.

[0059] 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.

[0060] Table 1: Target Slag Parameters

[0061] 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.

[0062] 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.

[0063] 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.

[0064] Table 2: Analysis of liquid metal products supplied to OBF (3.5-4.5 kg / 100 kg DRI)

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] In the accompanying drawings, the method for smelting metallic raw materials according to the present invention is generally indicated by reference numeral 10.

[0073] Figure 1 A schematic diagram of a method 10 for smelting metal-containing raw materials according to the present invention is shown. Figure 1 As shown, low-grade BF pellets; HBI, CDRI or HDRI (less than 66% Fe) 20, reducing agent and flux 30 are injected into OBF 40 to form at least one stock arrangement. When HDRI is unavailable, CDRI and HBI can be preheated in an inert atmosphere and conveyed by a hot-charge screw conveyor (not shown) and then fed to OBF 40. If no pretreatment is required, HDRI is conveyed by a hot-charge screw feeder (not shown) together with reducing agent and flux (cold-charged separately) and then fed to OBF 40 by a cold-charged vibrating feeder (not shown). Raw materials 20 and 30 are mainly loaded on the periphery of OBF 40 to form an optimal stock arrangement (e.g., Figure 3 , Figure 5 , Figure 6 (As shown in Figures 7(a) to 7(d)).

[0074] The power capacity of furnace 40 is up to 120 MW, typically 580-640 kWh / ton of liquid metal product, and the typical dosage of reducing agent is 40-60 kg / t of liquid metal product (carbon content higher than 4.0%).

[0075] The furnace 40 itself is made of a steel shell and is equipped with a refractory-based enclosure system, which can safely contain molten material at temperatures up to 1800°C. The weight loss and power-feed ratio system controls the furnace feed, while the feed burden level is controlled by radar within OBF 40 (not shown). Furnace 40 can be circular ( Figure 4 ) or rectangle ( Figure 2 Using three or six carbon electrodes (respectively). Figure 2 and Figure 4 ).

[0076] Liquid metal product 50 (see Table 2 above) and molten slag 60 (see Table 1) are intermittently discharged from OBF 40 and conveyed to downstream processes for the production of steel (from liquid metal product 50) and cement substitutes (from liquid slag product). Table 2 shows typical analyses of the liquid metal and molten slag products discharged from the OBF. Chemical analyses can be adjusted to represent most typical analyses of the molten metal and slag discharged from the blast furnace.

[0077] like Figure 8 As shown, the furnace 40 is equipped with a carbon spray gun 70, which can be strategically positioned to optimize the carbon supply position for carburizing the liquid metal product if needed.

[0078] Additional carburizing can also be accomplished by adding carbon to the torpedo. Liquid slag product 60 is typically discharged every 6 hours (80-150 tons, depending on the Fe feedstock grade). The net carbon footprint of this production method 10 is estimated to be 20%-40% of that of the conventional BF route.

[0079] Meanwhile, Method 10 provides an improved alternative to existing technologies, which can utilize low-grade raw materials while exhibiting a significantly lower carbon footprint and high-efficiency output. 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) The metal-containing raw material, reducing agent and flux are supplied to the open furnace (OBF) by supplying the metal-containing raw material from the periphery to the sidewall or from the periphery to the electrode, 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, wherein at least one material pile arrangement is formed during the supply process from the periphery to the sidewall. (ii) At a temperature of 1400°C to 1800°C, the metal-containing raw material is heated in OBF to fully melt the metal-containing raw material, thereby forming liquid metal product, liquid slag product and CO-containing gas; (iii) Carburizing of metal products by introducing a carbon source into the OBF; and (iv) Ensure a continuous supply of metallic raw materials, reducing agents and fluxes to the OBF to maintain at least one stockpile arrangement formed during the supply process from the periphery to the sidewalls; 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, waste, concentrate, or any combination of these materials, and the material or combination of the materials contains metallic iron (Fe) or a compound 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 claim 5, wherein, The pre-reduced iron ore is selected from the group consisting of hot-pressed iron (HBI), cold DRI (CDRI), and hot DRI (HDRI).

7. The method according to any one of claims 4-6, wherein, The pre-reduced iron ore is carbon-deficient or carbon-free HBI, CDRI, or HDRI.

8. The method according to claim 7, wherein, The pre-reduced iron ore is low-iron grade HBI, CDRI, or HDRI.

9. The method according to claim 7 or 8, wherein, The pre-reduced iron ore includes recycled waste.

10. The method according to any one of the preceding claims, wherein, The low-grade HBI or the cold or hot DRI is produced using 100% hydrogen to further reduce the CO2 footprint.

11. The method according to claim 1, wherein, By selecting to supply the metal-containing raw material to the OBF from the periphery to the sidewall or from the periphery to the electrode, the method achieves continuous replenishment of the iron-containing raw material, reducing agent, and flux, thereby ensuring that weight loss and power-feed balance are optimized.

12. The method according to claim 1, wherein, The OBF is a circular furnace.

13. The method according to claim 1, wherein, The OBF is a rectangular furnace.

14. The method according to claim 1, wherein, The OBF has a power capacity of up to 120 MW, typically 400-700 kWh / ton of molten metal, and a typical amount of reducing agent of 40-60 kg / ton of molten metal, resulting in a carbon content of more than 4.0% in the produced liquid metal product.

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, wherein, The liquid metal product has the following characteristic values: 。 17. 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.

18. 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.

19. The method according to any one of the preceding claims, wherein, In the method, the degree of iron metallization in the iron-containing raw material can be 86% to 94%.

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

21. The method according to claim 1, wherein, The carburizing is carried out in the torpedo or ladle.

22. 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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