Metallurgical furnace

Abstract

The present invention relates to metallurgical processes and equipment and, more particularly, to a metallurgical furnace capable of operating with a wide range of raw materials and fuels. To this end, the metallurgical furnace of the present invention comprises (i) at least one upper stack (1); (ii) at least one lower stack (2); (iii) at least one fuel inlet (10) positioned between the at least one upper stack (1) and the at least one lower stack (2); (iv) at least one charge inlet (3) positioned on the at least one upper stack (1); (v) at least one physical means (5) of internal separation of the upper stack (1) that extends longitudinally from the top thereof downwards, the physical means (5) being suitable for dividing the upper stack (1) into a central portion (6) and a peripheral portion (7); and (vi) at least one gas outlet (4) positioned on the upper part of the peripheral portion (7) of the at least one upper stack (1). The gas outlets (4) are responsible for generating a charge pre-heating region (7) that increases the operational flexibility of the furnace.

Description

METALLURGICAL FURNACE FIELD OF INVENTION

[0001] The present invention relates to metallurgical processes and equipment. More particularly, the present invention relates to a metallurgical furnace for producing pig iron. BACKGROUND OF THE INVENTION

[0002] Mining is an important activity for the country's economic development, accounting for approximately 20% of Brazilian exports in 2022. The mineral sector contributes to revenue generation, job creation, and improvements in the state's infrastructure. However, it is important to emphasize that mining also generates environmental and social impacts and must therefore be conducted responsibly and sustainably.

[0003] In the search for solutions that increasingly use less mineral raw materials, one of the trends in the steel production market is based on the use of by-products generated throughout the steel production chain. The traditional steel production route uses the blast furnace (BF) as a reduction reactor to obtain iron, which is then sent to the steel mill for steel production in oxygen converters (BOF - Basic Oxygen Furnace). Using the BF-BOF route, an average of 500 kg of waste is generated for each ton of liquid steel produced. Furthermore, each ton of liquid steel obtained from electric arc furnaces, which use scrap as the majority of the feedstock, generates approximately 185 kg of waste.

[0004] It's estimated that Brazil recycles tens of millions of tons of ferrous scrap annually. If all this material were sent to landfills, it would certainly create a serious environmental problem. Recycling and reusing this byproduct helps reduce the amount of waste released into the environment, preventing soil and water pollution, and saving natural resources and energy.

[0005] Currently, there are no metallurgical furnaces on the market capable of operating with a wide range of raw materials and fuels. In general, new structural and operational configurations are required to adapt the ferrous metal reduction process to the fuels used. Therefore, it is extremely important to develop flexible technologies that allow for the reuse and reuse of materials, aiming to mitigate environmental impacts without impacting process productivity or the quality of the products generated.

[0006] Document BR 10 2013 033702 1 A2, owned by the same Applicant, describes the insertion of burners in a self-reducing furnace that allows for greater versatility in the use of pulverized solid carbonaceous fuels, liquid fuels, and gaseous fuels. Despite their versatility, these fuels are considered auxiliary fuels, and their use is limited.

[0007] Patent BR 11 2017 012467 0 Bl, owned by the same Applicant, describes a self-reducing metallurgical furnace that operates with a preferential central hot air flow due to the presence of a hood (Curtain Wall) located in the upper tank that extends longitudinally through the furnace, which allows the use of ferrous materials of lower quality than ore, such as scrap, due to adequate control of the gas flow to enable the homogeneous reduction of the ferrous load. However, the tanks are sealed in such a way that the passage of air through the sides of the equipment is impossible, which hinders the counterflow of hot air in the load and, consequently, its preheating in the upper tank.

[0008] The invention proposed here solves the problems of the prior art described above in a simple and efficient manner. SUMMARY OF THE INVENTION

[0009] The present invention has as a first objective to provide a metallurgical furnace for the production of pig iron from raw materials varied, such as self-reducing briquettes produced from iron oxide sources, such as ores and steelmaking co-products, as well as scrap, scrap briquettes and HBI (Hot Briquetted Iron).

[0010] The present invention has as a second objective to provide a metallurgical furnace for the production of pig iron that is capable of operating with different types of fuels, which may be anthracite, fuel briquette, mineral coal, charcoal, metallurgical coke, green petroleum coke, as well as additional fuels, such as synthesis gas and H2.

[0011] The present invention has as a third objective to provide a flexible metallurgical furnace for the production of pig iron that is capable of contributing to the mitigation of environmental impacts and to increasing the energy efficiency of the metallurgical production process.

[0012] In order to achieve the objectives described above, the present invention provides a metallurgical furnace comprising (i) at least one upper tank; (ii) at least one lower tank; (iii) at least one fuel inlet positioned between the at least one upper tank and the at least one lower tank; (iv) at least one charge inlet positioned in the at least one upper tank; (v) at least one physical means for internal separation of the upper tank that extends longitudinally from the top thereof downwards, the physical means being adapted to divide the upper tank into a central portion and a peripheral portion; and (vi) at least one gas outlet positioned in the upper part of the peripheral portion of the at least one upper tank. BRIEF DESCRIPTION OF THE FIGURES

[0013] The detailed description presented below refers to the attached figures and their respective reference numbers.

[0014] Figure 1 shows a preferred embodiment of the metallurgical furnace according to the present invention.

[0015] Figure 2 shows a detailed view of the pre- heating the charge in the metallurgical furnace according to the preferred embodiment of the present invention.

[0016] Figure 3 shows a preferred embodiment of the metallurgical furnace according to the present invention where a plurality of gas outlets and charge inlets are provided. DETAILED DESCRIPTION OF THE INVENTION

[0017] As a preliminary point, it should be noted that the following description will be based on a preferred embodiment of the invention. As will be evident to anyone skilled in the art, however, the invention is not limited to that particular embodiment.

[0018] The present invention provides a metallurgical furnace equipped with innovations that allow adequate control of the gas flow, enabling the operation to be carried out in a versatile manner and with a wide range of raw materials and fuels.

[0019] The metallurgical furnace of the present invention, illustrated in figures 1 and 2, comprises at least one upper tank 1 where the charge (raw material) is inserted into the reactor. Preferably, the cross-section of the tank 1 is circular or rectangular. However, it should be noted that the present invention is not limited to any specific shape of the furnace.

[0020] The metallurgical furnace of the present invention further comprises at least one lower tank 2, preferably circular or rectangular in cross-section. The diameter or width of the cross-section of tank 2 is preferably larger than that of tank 1.

[0021] The present invention further comprises at least one fuel inlet 10 positioned between the at least one upper tank 1 and the at least one lower tank 2. Fuel supply ducts may be coupled to ensure the fuel load to the furnace bed, avoiding occurrences of load carryover when fine materials are used.

[0022] Preferably, the upper bowl 1 comprises a set The upper tuyere 8 and the lower bowl 2 comprise a set of lower tuyeres 9, which serve to blow hot or cold air into the metallurgical furnace. The blown air may optionally be enriched with O2. Solid powdered, liquid, or gaseous fuels may also be injected through the tuyeres for partial combustion of the fuel, producing gas and providing the thermal energy necessary for the reduction and / or melting of the charge. If hot air is blown into the tuyeres, blower assemblies 11, as illustrated in Figure 1, may also be used, which may be connected to an air heating system (not shown) known in the prior art.

[0023] The metallurgical furnace of the present invention further comprises at least one load inlet 3, preferably positioned in the upper lateral part of the upper tank 1.

[0024] Additionally, the metallurgical furnace of the present invention comprises a physical means 5 for internal separation of the upper tank 1, which extends longitudinally from the top thereof downwards, the physical means 5 being adapted to divide the upper tank 1 into a central portion 6 and a peripheral portion 7. Preferably, the physical means 5 is a hood (Curtain Wall) which extends longitudinally from the top of the upper tank 1 to half of its length, as shown in figures 1 and 2.

[0025] Preferably, the physical medium 5 is adapted to receive, from the top, permeabilizing fuel so as to form at least one column of permeabilizing fuel located in the central portion 6.

[0026] The metallurgical furnace of the present invention further comprises at least one gas outlet 4 positioned at the upper part of the peripheral portion 7 of the upper bowl 1. Preferably, the metallurgical furnace of the present invention comprises a plurality of gas outlets 4 and a plurality of charge inlets 3.

[0027] Preferably, a charging inlet 3 is provided adjacent to each gas outlet 4. In this preferred embodiment illustrated in figure 3, the metallurgical furnace of the present invention has a set of at least thirty-six charge inlets 3 and gas outlets 4.

[0028] The use of gas outlets (4) in the metallurgical furnace of the present invention significantly increases its efficiency. This occurs because the gas outlets (4) allow the upward flow of hot air from the lower tank (2) to also pass through the peripheral region, generating a preheating zone for the load. These gas outlets contribute to the formation of new convective currents within the furnace, increasing the efficiency of heat exchange and expanding operational control. This allows the furnace to be operated with a wide range of raw materials and fuels. The metallurgical furnace of the present invention, therefore, utilizes the heat generated within it more efficiently, which reduces the energy demand of the production process.

[0029] The metallurgical furnace of the present invention can be operated by any of the permeabilizing fuels of the group consisting of: anthracite, fuel briquette, mineral coal, charcoal, metallurgical coke, green petroleum coke, synthesis gas, H2.

[0030] The metallurgical furnace of the present invention can be operated with any load consisting of self-reducing briquettes produced from iron oxide sources, such as ores and steelmaking co-products, as well as scrap, scrap briquettes and HBI Hot Briquetted Iron).

[0031] The metallurgical furnace of the present invention has flexibility in controlling pressure, temperature and gas mixture in different regions of the furnace, allowing the same equipment to operate with different qualities of ferrous and fuel loads.

[0032] Numerous variations affecting the scope of protection of this application are permitted. This reinforces the fact that the present invention is not limited to the particular configurations / embodiments described above.

Claims

CLAIMS 1. Metallurgical furnace comprising: at least one upper bowl (1); at least one lower bowl (2); at least one fuel inlet (10) positioned between the at least one upper bowl (1) and the at least one lower bowl (2); at least one charge inlet (3) positioned in the at least one upper bowl (1); and at least one physical means (5) for internal separation of the upper bowl (1) that extends longitudinally from the top thereof downwards, the physical means (5) being adapted to divide the upper bowl (1) into a central portion (6) and a peripheral portion (7), characterized in that it additionally comprises: at least one gas outlet (4) positioned in the upper part of the peripheral portion (7) of the at least one upper bowl (1) for generating a charge preheating region;wherein for each gas outlet (4) of the at least one gas outlet (4) there is provided adjacently a charge inlet (3) of the at least one charge inlet (3), causing the inserted charge to come into contact with the charge preheating region.; 2. Metallurgical furnace, according to claim 1, characterized by the fact that the physical means (5) is adapted to receive, from above, permeabilizing fuel in the central portion (6) so as to form at least one column of permeabilizing fuel.

3. Metallurgical furnace, according to claim 1 or 2, characterized by the fact that the permeabilizing fuel is at least one of the group consisting of anthracite, fuel briquette, mineral coal, charcoal, metallurgical coke, green petroleum coke, and additional fuels such as synthesis gas and H2.

4. Metallurgical furnace according to any one of claims 1 to 3, characterized in that the charge is at least one of the group consisting of self-reducing briquettes produced from iron oxide sources, such as ores and steelmaking co-products, in addition to scrap, scrap briquettes and HBI Hot Briquetted Iron.

5. Metallurgical furnace according to any one of claims 1 to 4, characterized in that the at least one physical medium (5) extends longitudinally from the top of the upper tank (1) to half of its length.

6. Metallurgical furnace according to any one of claims 1 to 5, characterized in that the upper bowl (1) comprises a set of upper tuyeres (8) and the lower bowl (2) comprises a set of lower tuyeres (9).

7. Metallurgical furnace according to any one of claims 1 to 6, characterized in that blower assemblies (11) are connected to the tuyere assemblies (8, 9) to blow hot air into the metallurgical furnace.