Steel production plant comprising spacer sleeve

Abstract

The steel production plant (1) comprises an electric arc furnace (2) in which metal material is melted; and a ladle (4) in which the molten metal material is poured from an outlet (12) of the electric arc furnace (2). The steel production plant further comprises a sleeve (22) extending between the outlet (12) of the electric arc furnace (2) and the ladle (4), the molten metal material being poured from the outlet (12) of the electric arc furnace into said sleeve (22) and flowing to the ladle (4), said sleeve (22) being arranged to isolate the flow (20) of molten metal material flowing through said sleeve (22) from ambient air.

Description

Technical Field

[0001] The present invention relates to steel production equipment having the following types: an electric arc furnace in which metal material is melted; and a ladle in which molten metal material is poured from the outlet of the electric arc furnace. Background Technology

[0002] Steel can currently be produced via two main manufacturing routes. The most common route today, known as the "BF-BOF route," involves producing molten iron in a blast furnace (BF) by reducing iron oxides with a reducing agent (primarily coke), and then converting the iron into steel in a converter process or a basic oxygen converter (BOF). This route releases significant amounts of CO2, both in the coking plant's coke production and in the iron production process.

[0003] The second main route involves the so-called "direct reduction method." This includes methods under the trademarks MIDREX®, FINMET®, ENERGIRON® / HYL, COREX®, FINEX®, etc., in which sponge iron is produced by directly reducing an iron oxide carrier in the form of HDRI (Hot Direct Reduced Iron), CDRI (Cold Direct Reduced Iron), or HBI (Hot Briquetted Iron). The sponge iron in HDRI, CDRI, and HBI forms undergoes further processing in an electric arc furnace (EAF) to produce steel.

[0004] Therefore, one of the main options chosen by steelmakers to reduce CO2 emissions is the shift from the BF-BOF route to the DRI-EAF route. However, using DRI products with scrap steel in conventional electric arc furnaces has some limitations. In reality, scrap steel contains a significant amount of impurities, and the resulting molten steel will require further processing to produce high-quality steel grades. Furthermore, to date, electric arc furnaces have been used to produce specific steel grades, primarily for long product applications, which does not have the same limitations in metallurgy as those specifically for steel grades used in automotive products.

[0005] For example, molten steel produced from a basic oxygen converter contains 20 to 90 parts per million (ppm) of nitrogen, compared to 100 to 140 ppm of nitrogen in molten steel produced in an electric arc furnace (EAF). Therefore, current EAF steels have significantly higher nitrogen content than BOF steels and fail to meet the requirements for high-grade steels. High nitrogen content can lead to inconsistent mechanical properties in hot-rolled steels, embrittlement of the heat-affected zone (HAZ) in welded steels, and poor cold formability. Summary of the Invention

[0006] One of the objectives of this invention is to solve this problem by proposing a steel production device that reduces the nitrogen content of molten steel produced in an electric arc furnace.

[0007] Therefore, the present invention relates to steel production equipment of the above type, wherein the steel production equipment further includes a sleeve extending between the outlet of the electric arc furnace and the ladle, wherein molten metal material is poured from the outlet of the electric arc furnace into the sleeve and flows to the ladle, and the sleeve is arranged to isolate the flow of molten metal material flowing through the sleeve from the ambient air.

[0008] Passing the molten metal through a sleeve between the outlet of the electric arc furnace and the ladle allows for a reduction in the exposure of the molten metal to the atmosphere as it flows from the furnace to the ladle. Consequently, nitrogen absorption caused by the molten metal is significantly limited, and the quality of the produced steel is improved.

[0009] Steel production equipment may also include the following features, either individually or in any technically feasible combination:

[0010] - The sleeve extends between an upper end and a lower end, the upper end being attached in a liquid-tight manner to the outlet of the electric arc furnace, and the lower end extending within the internal volume of the ladle.

[0011] - The sleeve includes at least one inert material injection inlet in fluid communication with an inert material source, the inert material injection inlet being located inside the sleeve around an opening for a flow of molten metal material flowing through the sleeve.

[0012] - The inert material is argon.

[0013] - The sleeve includes at least one additive injection inlet in fluid communication with an additive source fluid, the additive injection inlet being located inside the sleeve around an opening for a flow of molten metal material flowing through the sleeve.

[0014] - The additives include at least one mineral and / or at least one iron alloy.

[0015] - The sleeve includes a slag detection device arranged to detect slag in the molten metal flow.

[0016] - The steel production equipment includes at least one additive inlet into the internal volume of a ladle for introducing at least one additive into the molten metal material within the ladle.

[0017] - The additives must include at least carbon.

[0018] - The added carbon is biomass-based carbon, such as biochar, recycled carbon including graphite refractories, graphite material byproducts, coke powder, and petroleum coke.

[0019] - An electric arc furnace includes: an internal volume in which a metallic material is melted; and at least one electrode capable of being positioned in the internal volume to generate an electric arc in the internal volume, thereby melting the metallic material.

[0020] - The electrodes can move relative to the internal volume, making the depth of the electrodes in the metallic material adjustable.

[0021] - The metal material melted in the electric arc furnace contains at least 40% direct reduced iron by weight.

[0022] - The metal material melted in the electric arc furnace contains 40% to 60% direct reduced iron by weight. Attached Figure Description

[0023] Other aspects and advantages of the invention will become apparent after reading the following description, which is given by way of example and with reference to the accompanying drawings, wherein:

[0024] - Figure 1 This is a cross-sectional schematic diagram of the steel production equipment according to the present invention. Detailed Implementation

[0025] refer to Figure 1 It describes a steel production equipment 1 that includes an electric arc furnace 2 and a ladle 4.

[0026] An electric arc furnace 2 is arranged to receive metallic material to be melted. For this purpose, the electric arc furnace 2 includes an internal volume 6 into which the metallic material is introduced. The metallic material includes, for example, scrap steel. The scrap steel may be melted together with pig iron and / or direct reduced iron (DRI). For example, usable scrap steel is referred to as old scrap (E1 or E3), new scrap (E8), shredded scrap 20 (E40), or fragmented scrap (E46) in the EU-21 scrap steel specification. In a preferred embodiment, the material melted in the electric arc furnace 2 contains at least 40% by weight, preferably 40% to 60% by weight, direct reduced iron.

[0027] The percentage of DRI and / or pig iron in the charge is highly dependent on the available scrap steel and the quality of the steel to be produced. If the levels of impurities such as copper, chromium, molybdenum, nickel, tin, antimony, zinc, and / or arsenic are low, the amount of scrap steel to be charged can be increased, and thus the amount of DRI can be reduced.

[0028] The electric arc furnace 2 also includes at least one electrode 8, which is positioned within the internal volume 6 to generate arc radiation heat within the internal volume 6. For this purpose, the electrode 8 is electrically connected to a power source (not shown) and extends at least partially within the internal volume 6. The electrode 8 preferably operates using CO2-neutral electricity, which specifically includes electricity from renewable sources, defined as energy generated by renewable resources that are naturally replenished on a human timescale, including sources such as sunlight, wind, rain, tides, waves, and geothermal energy. In some embodiments, electricity from nuclear sources may be used because it does not emit CO2 to be produced.

[0029] According to the embodiment, the electrode 8 is movable relative to the internal volume 6, such that the depth of the electrode 8 within the stack of metal material placed in the electric arc furnace 2 is adjustable. More specifically, the electrode 8 extends, for example, through an opening in the furnace top 10 of the electric arc furnace 2, which encloses the internal volume 6. The electrode 8 is capable of translational movement within the opening, such that the length of the electrode 8 extending within the internal volume 6 is adjustable.

[0030] By moving electrode 8 relative to the metal material, the electric arc from electrode 8 can gradually cause the metal material to melt, and as the metal material is melted and liquefied, it penetrates the metal material, so that the metal material can be completely melted when electrode 8 approaches the bottom of the metal material. The length of the electric arc is also adjustable, so that the arc is shorter when electrode 8 is lowered toward the unmelted metal material, and longer when electrode 8 has penetrated the metal material. In this way, when the tip of electrode 8 is kept close to the furnace top 10, the heat radiated by the electric arc will not be transferred to the furnace top 10 of the electric arc furnace 2. As the tip of electrode 8 extends into the metal material, the electric arc can be lengthened to increase the heat radiated by the electric arc.

[0031] according to Figure 1 In the illustrated embodiment, the electric arc furnace 2 includes a plurality of parallel electrodes 8. More specifically, multiple electrodes 8 are provided for an electric arc furnace powered by alternating current. When the electric arc furnace is powered by direct current, a single electrode can be used.

[0032] According to the implementation plan, the electric arc furnace 2 may also include one or more burners to assist the electrode 8 in melting the metal material.

[0033] The electric arc furnace 2 includes an outlet 12 for pouring molten metal material out of the internal volume 6 of the electric arc furnace 2. The outlet 12 extends, for example, below the internal volume 6, allowing the molten metal material to flow through the outlet 12 by gravity. A valve (not shown) is provided, for example, to open or close the outlet 12.

[0034] The ladle 4 forms a container for receiving molten metal for further processing as known per se. For this purpose, the ladle 2 includes an internal volume 14 accessible via an upper opening 16 through which the molten metal flows into the internal volume 14 of the ladle 4. Figure 1 As shown, the ladle 4 is placed, for example, on the trolley 18, allowing the ladle 4 to move between different processing stations, including below the electric arc furnace 2, and more particularly below the outlet 12 of the electric arc furnace 2.

[0035] When the metal material in the internal volume 6 of the electric arc furnace 2 has melted and the ladle 4 is placed below the outlet 12 of the electric arc furnace 2, as Figure 1 As shown, molten metal material is allowed to flow from the internal volume 6 through the outlet 12 and the upper opening 16 of the ladle 4 into the internal volume 14 of the ladle 4 in the form of a molten metal material stream 20. Between the outlet 12 and the upper opening 16, the molten metal material stream 20 is exposed to the atmosphere, where the metal material interacts with the ambient air and is able to absorb nitrogen.

[0036] To minimize nitrogen absorption, the steel production apparatus 1 according to the invention includes a sleeve extending between the outlet 12 of the electric arc furnace 2 and the ladle 4, through which the molten metal flow 20 flows from the outlet 12 into the internal volume 14 of the ladle 4. The sleeve 22 is arranged to isolate the molten metal flowing through it from the ambient air, such that nitrogen absorption caused by the molten metal is effectively prevented as it flows through the sleeve. The sleeve 22 is made, for example, of a refractory material, such as oxides of aluminum, silicon, magnesium, zirconium, calcium, or mixtures thereof.

[0037] The sleeve 22 extends between the upper end 24 and the lower end 26, with the upper end 24 attached to the outlet 12 of the electric arc furnace 2 and the lower end 26 extending within the internal volume 14 of the ladle 4.

[0038] Between the upper end 24 and the lower end 26, the sleeve 22 includes a wall 28 defining an internal channel 30, which is isolated from ambient air. The internal channel 30 may have, for example, a circular cross-section larger than the cross-section of the molten metal flow 20. It should be understood that other cross-sectional shapes may also be considered.

[0039] According to the embodiment, the upper end 24 is attached to the outlet 12 via a connector. The connector is attached to the outlet 12, and the sleeve 22 is nested on the connector. The connector is arranged to place the outlet 12 in fluid communication with the internal channel 30 of the sleeve. The connector, for example, has an external shape substantially complementary to the shape of the internal channel 30 at the upper end 24 of the sleeve 22. According to a particular example, the external shape of the connector is substantially conical, and the diameter decreases from the outlet 12 toward the internal channel 30.

[0040] At the upper end 24, the internal channel 30 is in fluid communication with the internal volume 6 of the electric arc furnace 2. The sleeve 22 is attached to the outlet 12 of the electric arc furnace 2 in a liquid-tight manner at the upper end 24, so that when it is poured out of the internal volume 6 of the electric arc furnace 2, the molten metal material flow 20 flows completely into the internal channel 30 of the sleeve 22.

[0041] At its lower end 26, the sleeve 22 opens into the internal volume 14 of the ladle 4, allowing the internal channel 30 to fluidly communicate with the internal volume 14 of the ladle 4 at the lower end 26. More specifically, the lower end 26 of the sleeve 22 extends, for example, near the bottom 32 of the internal volume 14 of the ladle 4, such that when the molten metal fills the internal volume 14 of the ladle 4, the lower end 26 is rapidly immersed in the molten metal. This allows for further reduction of the contact between the molten metal and ambient air, as the molten metal flowing out from the lower end 26 of the sleeve 22 flows into the molten metal already present in the internal volume 14 of the ladle 4, without contacting the ambient air.

[0042] According to a particular embodiment, the sleeve 22 includes at least one inert material injection inlet 34 in fluid communication with an inert material source 36. The inert material injection inlet 34 is located inside the sleeve 22, i.e., at the opening of an internal channel 30 into the sleeve 22, allowing inert material to be injected around a stream of molten metal flowing within the internal channel 30. The inert material is arranged to neutralize the interaction between the molten metal stream 20 and the ambient air, such that the metal does not absorb nitrogen if it comes into contact with the atmosphere. The inert material is injected around the molten metal stream 20, for example, in gaseous form. The inert material is, for example, argon. The inert material injection inlet 34 extends, for example, near an upper opening 24 of the sleeve 22, and the inert material is drawn towards the lower end 26 of the sleeve by the molten metal stream 20.

[0043] According to a specific embodiment that can be combined with the above embodiments, the sleeve 22 includes at least one additive injection inlet 38 in fluid communication with the additive source 40. The additive injection inlet 38 is located inside the sleeve 22, i.e., at the opening of the internal channel 30, allowing at least one additive to be injected around the molten metal flow 20 flowing within the internal channel 30. The additive can be used to treat the metal material as it flows within the sleeve 20, thereby utilizing the fluid dynamics of the molten metal in the sleeve 20. The additive includes, for example, at least one mineral and / or at least one ferroalloy. According to a specific embodiment, coke is injected into the internal channel 30 via the additive injection inlet 38 to react with oxygen dissolved in the melt. Alternatively or additionally, lime powder is injected into the internal channel 30 via the additive injection inlet 38 or another additive injection inlet (not shown) to desulfurize the metal material as it flows from the internal volume 6 of the electric arc furnace 2 to the internal volume 14 of the ladle 4.

[0044] According to an embodiment that can be combined with the above-described embodiments, the sleeve 20 includes a slag detection device 42, which is arranged to detect slag in the molten metal flow 20 flowing from the internal volume 6 of the electric arc furnace to the internal volume 14 of the ladle 4. Such a slag detection device 42 is, for example, an electromagnetic sensor. The slag detection device 42 allows monitoring of slag entrainment from the electric arc furnace 2 to the ladle 4, which is detrimental to the quality of the molten metal, as the slag is improperly melted metal.

[0045] According to the implementation scheme, the steel production equipment 1 also includes at least one additive inlet 44 for introducing at least one additive into the molten metal material in the ladle 4. Such an additive is added to the molten metal material to become one of the components of the steel produced in the steel production equipment. Such additives are, for example, carbon, silicon, and / or aluminum, or a mixture of at least two of these materials. The added carbon can be biomass-based carbon, such as biochar, recycled carbon including graphite refractories, graphite material byproducts (graphite powder), coke powder, or petroleum coke. Biochar is preferred. Biochar refers to charcoal produced by the pyrolysis of biomass under anaerobic conditions. Biomass is a renewable organic material derived from plants and animals. Biomass sources used for energy include wood and wood processing waste—firewood, wood pellets and sawdust, sawdust and waste from wood and furniture factories, and black liquor from pulp and paper mills; agricultural crops and waste—corn, soybeans, sugarcane, switchgrass, woody plants and algae, as well as agricultural and food processing residues; biomaterials in municipal solid waste paper, cotton and wool products; and food, yard and wood waste, as well as animal manure and human sewage.

[0046] Additive inlet 44 is arranged such that additives are introduced into the molten metal material in ladle 4 via upper opening 16. Additive inlet 44 is in fluid communication with at least one additive source (not shown). It should be understood that several additive inlets may be provided near upper opening 16 of ladle 4, for example, one inlet for each type of additive to be added to the molten metal material.

[0047] As is known to all, once the additives have been added to the molten metal, the ladle 4 can be moved to a subsequent processing station, such as a ladle furnace, to complete the steel production.

[0048] The sleeve 22 according to the invention allows for effective reduction of the interaction between the molten metal flow 20 and the ambient air during the pouring of molten metal into the ladle 4. Therefore, the molten metal absorbs little or no nitrogen from the atmosphere, thereby improving the composition of the finished steel produced using the steel production equipment 1.

Claims

1. A steel production apparatus (1), comprising an electric arc furnace (2) in which metal material is melted; and a ladle (4) in which the molten metal material is poured from the outlet (12) of the electric arc furnace (2), characterized in that, The steel production equipment also includes a sleeve (22) extending between the outlet (12) of the electric arc furnace (2) and the ladle (4), wherein the molten metal material is poured from the outlet (12) of the electric arc furnace into the sleeve (22) and flows to the ladle (4), and the sleeve (22) is arranged to isolate the flow (20) of the molten metal material flowing through the sleeve (22) from the ambient air.

2. The steel production equipment according to claim 1, wherein, The sleeve (22) extends between an upper end (24) and a lower end (26), the upper end (24) being attached in a liquid-tight manner to the outlet (12) of the electric arc furnace (2), and the lower end (26) extending within the internal volume (14) of the ladle (4).

3. The steel production equipment according to claim 1 or 2, wherein, The sleeve (22) includes at least one inert material injection inlet (34) in fluid communication with an inert material source (36), the inert material injection inlet (34) opening inside the sleeve (22) around the flow (20) of the molten metal material flowing through the sleeve (22).

4. The steel production equipment according to claim 3, wherein, The inert material is argon.

5. The steel production equipment according to any one of claims 1 to 4, wherein, The sleeve (22) includes at least one additive injection inlet (38) in fluid communication with an additive source (40), the additive injection inlet (38) opening inside the sleeve (22) around the flow (20) of the molten metal material flowing through the sleeve (22).

6. The steel production equipment according to claim 5, wherein, The additives include at least one mineral and / or at least one iron alloy.

7. The steel production equipment according to any one of claims 1 to 6, wherein, The sleeve (22) includes a slag detection device (42) which is arranged to detect slag in the molten metal material stream (20).

8. The steel production equipment according to any one of claims 1 to 7, further comprising at least one additive inlet (44) into the internal volume (14) of the ladle (4) for introducing at least one additive into the molten metal material in the ladle (4).

9. The steel production equipment according to claim 8, wherein, The additives include at least carbon.

10. The steel production equipment according to claim 9, wherein, The added carbon is biomass-based, such as biochar, recycled carbon including graphite refractories, graphite material byproducts, coke powder, and petroleum coke.

11. The steel production equipment according to any one of claims 1 to 10, wherein, The electric arc furnace (2) includes an internal volume (6) in which the metal material is melted; and at least one electrode (8) capable of being positioned in the internal volume (6) to generate an electric arc in the internal volume (6) thereby melting the metal material.

12. The steel production equipment according to claim 11, wherein, The electrode (8) is movable relative to the internal volume (6), such that the depth of the electrode (8) in the metal material is adjustable.

13. The steel production equipment according to any one of claims 1 to 12, wherein, The metal material melted in the electric arc furnace (2) contains at least 40% direct reduced iron by weight.

14. The steel production equipment according to claim 13, wherein, The metal material melted in the electric arc furnace (2) contains 40% to 60% direct reduced iron by weight.

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