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

FIELD OF THE INVENTION

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

[0002] Mining is an important activity for the country's economic development, accounting for approximately 20% of the Brazilian exports in 2022. The mining 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; therefore, it must be conducted responsibly and sustainably.

[0003] In order to seek solutions that use less and 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 a blast furnace (BF) as a reduction reactor to obtain iron, which is then sent to the steel mill for steel production in basic oxygen converters (BOF). Using the BF-BOF route, an average of 500 kg of waste is generated for each ton of liquid steel produced. In addition, each ton of liquid steel obtained from electric arc furnaces, which use scrap as the majority of the charge, generates approximately 185 kg of waste.

[0004] It is estimated that ferrous scrap recycling in Brazil amounts to tens of millions of tons per year. If all of this material were sent to landfills, it would certainly create a serious environmental problem. Recycling and reusing this byproduct help reduce the amount of waste released into the environment, preventing soil and water pollution, in addition to 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 reduction process of the ferrous sources to the fuels used. Accordingly, it is extremely important to develop flexible technologies that aim to reuse and recycle materials, with the objective of mitigating environmental impacts without impacting the 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 B1, 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 stack that extends longitudinally through the furnace, which allows the use of lower-quality ferrous materials than ore, such as scrap, due to adequate control of the gas flow to enable the homogeneous reduction of the ferrous charge. However, the stacks 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 charge and, consequently, its preheating in the upper stack.

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

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

[0010] The present invention has as its second objective to provide a metallurgical furnace for the production of pig iron that is capable of operating with various types of fuels, which can be anthracite, fuel briquettes, mineral coal, charcoal, metallurgical coke, green petroleum coke, as well as additional fuels, such as synthesis gas and H 2 .

[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 the 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 stack; (ii) at least one lower stack; (iii) at least one fuel inlet positioned between the at least one upper stack and the at least one lower stack; (iv) at least one charge inlet positioned in the at least one upper stack; (v) at least one physical means for internal separation of the upper stack that extends longitudinally from the top thereof downwards, the physical means being adapted to divide the upper stack 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 stack.BRIEF DESCRIPTION OF THE FIGURES

[0013] The detailed description presented below refers to the attached figures and their respective reference numerals. Figure 1 shows a preferred embodiment of the metallurgical furnace according to the present invention. Figure 2 shows a detailed view of the charge preheating region in the metallurgical furnace according to the preferred embodiment of the present invention. 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

[0014] As a preliminary point, it should be emphasized that the following description will be based on a preferred embodiment of the invention. As will be evident to anyone skilled on the subject, however, the invention is not limited to this particular embodiment.

[0015] 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.

[0016] The metallurgical furnace of the present invention, illustrated in Figures 1 and 2, comprises at least one upper stack 1 where the charge (raw material) is inserted into the reactor. Preferably, the cross-section of the stack 1 is circular or rectangular. However, it should be emphasized that the present invention is not limited to any specific shape of the furnace.

[0017] The metallurgical furnace of the present invention further comprises at least one lower stack 2, preferably with a circular or rectangular cross-section. The diameter or width of the cross-section of the stack 2 is preferably larger than that of the stack 1.

[0018] The present invention further comprises at least one fuel inlet 10 positioned between the at least one upper stack 1 and the at least one lower stack 2. Fuel supply ducts can be coupled to ensure the fuel is fed to the furnace bed, preventing charge carryover when fine materials are used.

[0019] Preferably, the upper stack 1 comprises a set of upper tuyeres 8 and the lower stack 2 comprises 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 O 2 . Solid powdered, liquid, or gaseous fuels may further 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, it is further possible to use blower sets 11, as illustrated in figure 1, which can be connected to an air heating system (not shown) known in the state of the art.

[0020] The metallurgical furnace of the present invention further comprises at least one charge inlet 3, preferably positioned in the lateral upper part of the upper stack 1.

[0021] Additionally, the metallurgical furnace of the present invention comprises a physical means 5 for internal separation of the upper stack 1, which extends longitudinally from the top thereof downwards, the physical means 5 being adapted to divide the upper stack 1 into a central portion 6 and a peripheral portion 7. Preferably, the physical means 5 is a hood (Curtain Wall) that extends longitudinally from the top of the upper stack 1 to half its length, as shown in Figures 1 and 2.

[0022] Preferably, the physical means 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.

[0023] 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 stack 1. Preferably, the metallurgical furnace of the present invention comprises a plurality of gas outlets 4 and a plurality of charge inlets 3.

[0024] Preferably, for each gas outlet 4, a charge inlet 3 is provided adjacently. 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.

[0025] The use of gas outlets 4 in the metallurgical furnace of the present invention considerably increases its efficiency. This occurs because the gas outlets 4 allow the upward flow of hot air from the lower stack 2 to also pass through the peripheral region, generating a charge preheating region therein. These gas outlets contribute to the formation of new convective currents within the furnace, increasing heat exchange efficiency and expanding the 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.

[0026] The metallurgical furnace of the present invention can be operated with any of the permeabilizing fuels from the group consisting of: anthracite, fuel briquette, mineral coal, charcoal, metallurgical coke, green petroleum coke, synthesis gas, H 2 .

[0027] The metallurgical furnace of the present invention can be operated with any charge consisting of self-reducing briquettes produced from iron oxide sources, such as ores and steelmaking by-products, as well as scrap, scrap briquettes, and HBI (Hot Briquetted Iron).

[0028] The metallurgical furnace of the present invention presents flexibility in controlling pressure, temperature, and gas mixing in different regions of the furnace, allowing the same equipment to operate with varying qualities of ferrous charges and fuels.

[0029] Numerous variations affecting the scope of protection of the present application are permitted. In this way, it is emphasized that the present invention is not limited to the particular configurations / embodiments described above.

Claims

1. A metallurgical furnace comprising: at least one upper stack (1); at least one lower stack (2); at least one fuel inlet (10) positioned between the at least one upper stack (1) and the at least one lower stack (2); at least one charge inlet (3) positioned on the at least one upper stack (1); and 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); characterized in that it further comprises: at least one gas outlet (4) positioned on the upper part of the peripheral portion (7) of the at least one upper stack (1) to generate a charge pre-heating region; in which for each gas outlet (4) of the at least one gas outlet (4), a charge inlet (3) of the at least one charge inlet (3) is provided adjacently, causing the inserted charge to come into contact with the charge preheating region.

2. The metallurgical furnace according to claim 1, characterized in 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. The metallurgical furnace according to claim 1 or 2, characterized in 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. The 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 by-products, as well as scrap, scrap briquettes, and HBI (Hot Briquetted Iron).

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

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

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

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