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Title:
COOLED BOX FOR POSITIONING NOZZLES IN ARC FURNACES
Document Type and Number:
WIPO Patent Application WO/2008/136027
Kind Code:
A1
Abstract:
The present invention relates to a cooled box (1) for positioning nozzles (30) in arc furnaqes (2) . The box comprises a tubular body (10) which, in turnf comprises a plurality of ingots (20) that are mutually fastened and arranged such as to be the tubular body side walls.

Inventors:
MIANI STEFANO (IT)
BARBANO ALESSANDRO (IT)
RUBEO BRUNO (IT)
Application Number:
PCT/IT2007/000336
Publication Date:
November 13, 2008
Filing Date:
May 07, 2007
Export Citation:
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Assignee:
CONCAST STANDARD AG (CH)
MIANI STEFANO (IT)
BARBANO ALESSANDRO (IT)
RUBEO BRUNO (IT)
International Classes:
F27D1/12; C21C5/46; C21C5/52; F23M5/02; F23M5/08; F27B3/20
Foreign References:
DE4138091A11992-05-21
Attorney, Agent or Firm:
BELLONI, Giancarlo et al. (Via Senato 8, Milano, IT)
Download PDF:
Claims:

CLAIMS

1. A cooled box (1) for positioning nozzles within an arc furnace (2), comprising a tubular body (10), said tubular body (10) comprising a plurality of ingots (20) which are mutually fastened and arranged such as to be the side walls of said tubular body (10) .

2. ' " The ~~ cooled box ~~ (±) according to the preceding claim-, wherein the tubular body (10) defines an axis X.

3. The cooled box (1) according to any preceding claim, comprising a circumferentially segmented structure.

4. The cooled box (1) according to claim 2, wherein the ingots (20) are arranged substantially in the axis X direction and are mutually juxtaposed along contact lines and/or surfaces that are substantially arranged in the axis X direction.

5. The cooled box. (1) according to claim 2, wherein. the ingots (20) are substantially arranged in the axis X direction and are mutually fastened along junction lines that are substantially arranged in the axis X direction.

6. The cooled box (1) according to any preceding claim, wherein a longitudinal axis Y of each single ingot is enclosed in a plane passing along the axis X.

7. The cooled box (1) according to any preceding claim, wherein the contact lines and/or surfaces between two

adjacent ingots are enclosed in planes passing along the axis X.

8. The cooled box (1) according to any preceding claim, wherein the ingots (20) are arranged such as to form an approximately frusto-conical or frusto-pyramidal shape.

9. The cooled box (1) according to any preceding claim, wherein a longitudinal axis Y of each single ingot forms, with the axis X, an angle α having a width ranging between 1° and 4°, preferably 2°.

10. The cooled box (1) according to any claim 1 to 7, wherein the ingots are arranged such as to form an approximately cylindrical or prismatic shape.

11. The cooled box (1) according to any claim 1 to 7, wherein a longitudinal axis Y of each individual ingot is parallel to the axis X.

12. The cooled box (1) according to any preceding claim, wherein the tubular body (10) of the box (1) comprises a channel (11) therein, which is adapted to house a nozzle (30).

13. The cooled box (1) according to the preceding claim, wherein said channel (11) has a regular polygon-shaped section.

14. The cooled box (1) according to claim 12, wherein said channel (H) has a section having a shape selected

from the group comprising: irregular polygons, circumferences, ellipses, λ 8' shape.

15. The cooled box (1) according to any claim 12 to 14, wherein the channel (11) has a diameter ranging between 100 and 400 mm, preferably between 120 and 250 mm.

16. The cooled box (1) according to any preceding claim, wherein the ingots (20) comprise a channel (21) therein for the circulation of the cooling fluid.

17. The cooled box (1) according to the preceding claim, wherein the channel (21) of each ingot (20) is substantially U-shaped, is formed by two rectilinear and parallel conducts (211, 212) running almost the whole length of the ingot, which are mutually connected by a third transversal conduct (213) . 18. The cooled box (1) according to any claim 16 to 17, wherein the cooling channel (21) of each ingot (20) is connected to the cooling channels of the other ingots

(20) , such as to form an individual cooling circuit (12) which runs through the whole tubular body (10) . 19. The cooled box (1) according to the preceding claim, wherein the channels (21) of the ingots (20) are mutually connected in series .

20. The cooled box (1) according to claim 18, wherein the channels (21) of the ingots (20) are mutually connected in parallel or according to a mixed in-

series/parallel scheme.

21. The cooled box (1) according to any preceding claim, wherein each ingot (20) comprises a shoulder (23) on the side intended to be the inner wall of the tubular body (10) .

22. The cooled box (1) according to any preceding claim, wherein the tubular body (10) comprises, within the channel (11) , a diaphragm (13) .

23. The cooled box (1) according to claim 21 and 22, wherein said diaphragm (13) comprises said shoulders

(23) .

24. The cooled box (1) according to any preceding claim further comprising a shield (6) .

25. The cooled box (1) according to any preceding claim further comprising a protective pipe fitting (7) .

26. The cooled box (1) according to claim 24 wherein the inclination of the X axis of the tubular body (ϊt>) relative to the shield (6) ranges between 30° and 60°, preferably it ranges between 40° and 50°. 27. The cooled box (1) according to any preceding claim, wherein the length of each ingot (20) ranges between 350 and 550 mm, preferably between 420 and 480 mm. 28. The cooled box (1) according to any preceding claim, wherein the total usable length of the tubular body (10) is substantially equal to the length of the individual

ingot (20) .

29. The cooled box (1) according to any preceding claim, wherein the ingots (20) are made of copper.

30. The cooled box (1) according to any claim 1 to 28, wherein the ingots (20) are made of a material selected from the group comprising: steel, sinterized ceramic materials, alumina, sinterized superalloys, Inconel, and Hastelloy.

31. The cooled box (1) according to any preceding claim, wherein the ingots are made from an individual monolithic block .

32. The cooled box (1) according to any claim 1 to 30, wherein each ingot (20) comprises a main body (22) and a nose (24) . 33. The cooled box (1) according to the preceding claim, wherein the main body (22) is run through by the cooling channel (21) , while the nose (24) is not run through by the cooling channel (21) .

34. The cooled box (1) according to claim 32 or 33, wherein the nose (24) is made of a material which is different from the one composing the main body (22) of the ingot (20) .

35. The cooled box (1) according to any claim 32 to 34, wherein the ingot (20) comprises a plating (25) of the nose (24) being made with a layer of a material which is

different from the one composing the main body (22) .

36. The cooled box (1) according to any claim 32 to 35, wherein the main body (22) , the nose (24) , and/or the plating (25) are made of copper, steel, ceramic material, or superalloy.

37. The cooled box (1) according to any claim 32 to 36, wherein the nose (24) , and/or the plating (25) are interchangeable, such as to be able to be easily replaced without removing the main body (22) of the ingot (20) from the tubular body (10) .

38. The cooled box (1) according to any claim 32 to 37, wherein the ingot (20) comprises a surface treatment (26) of the nose (24) , said treatment comprising an anti-wear material layer applied by plasma spraying. 39. The cooled box (1) according to the preceding claim, wherein said anti-wear material comprises alumina and/or zirconia.

40. The cooled box (1) according to any preceding claim, wherein the ingots (20) are mutually fastened by welding along the side surfaces.

41. The cooled box (1) according to any preceding claim, wherein the ingots (20) are mutually fastened by a shape coupling.

42. The cooled box (1) according to the preceding claim, wherein the ingots (20) are mutually fastened by a

dovetail fitting.

43. The cooled box (1) according to any preceding claim, wherein the ingots (20) are fastened through an outer rimming- (14) . 44. The cooled box (1) according to any preceding claim, further comprising a sealing ring (15) adapted to seal the interspace that may be present between the nozzle (30) and the channel (11) , particularly between the nozzle (30) and the diaphragm (13) . 45. The cooled box (1) according to the preceding claim, wherein said sealing ring (15) is made of a material comprising ceramic fibers, glass fibers, steel fibers, or other materials adapted to create a barrier which is resistant to the working temperatures of the furnace. 46. The cooled box (1) according to claim 18, wherein the cooling circuit (12) comprises a ring (16) which is suitable to connect the individual cooling channels (21) of the ingots (20) and two hoses (17, 18) for the connection of the circuit (12) to the feeding and outflow lines of the cooling fluid.

47. The cooled box (1) according to any preceding claim, wherein at least one ingot (20) comprises a conduct (211, 212) extending until it opens on the nose (24) of the ingot (20) . 48. The cooled box (1) according to the preceding claim,

wherein the at least one ingot (20) comprising the conduct (211, 212) extending until it opens on the nose (24) of the ingot (20) has a larger size than the other ingots (20) . 49. A method for manufacturing a tubular body (10) of a cooled box (1) according to any preceding claim, comprising the steps of:

- providing a plurality of ingots (20) ;

- creating a cooling channel (21) within each ingot (20) ;

- mutually fastening the ingots (20) by placing them in such an arrangement as to form the tubular body (10) side walls;

- connecting the individual cooling channels (21) such as to form an individual cooling circuit (12) .

50. The method according to the preceding claim, wherein the step of providing the ingots (20) comprises a step of drawing the material.

51. The method according to the claim 49, wherein the step of arranging the ingots (20) comprises a step of sintering, casting, and/or moulding.

52. The method according to any claim 49 to 51, wherein the step of arranging the ingots (20) comprises a step of applying a shoulder (23) . 53. The method according to any claim 49 to 52, wherein

the step of arranging the ingots (20) comprises the arrangement of two special ingots that are intended to be respectively located as the first and the last in the series. 54. The method according to claim 49, wherein the step of creating a cooling channel (21) within an ingot (20) comprises a double step of longitudinal deep drilling the ingot (20) , such as to create two rectilinear and parallel conducts (211, 212) . 55. The method according to the preceding claim, wherein the step of creating a cooling channel (21) further comprises a milling step suitable to produce a third conduct (213) transversal to the first two conducts (211, 212) . 56. The method according to the preceding claim, wherein the step of creating a cooling channel (21) further comprises a step of inserting a cap (214) suitable to restore the sealing of the channel (21) at the third conduct (213) obtained by milling. 57. The method according to claim 49, wherein the step of arranging n ingots (20) comprises creating two contact side surfaces (27, 28) upon each ingot, which mutually form a 360°/n wide angle β, the contact side surfaces (27, 28) being suitable to contact the corresponding surfaces of the adjacent ingots.

58. The method according to the preceding claim, wherein the contact side surfaces (27, 28) are obtained by- machine tooling.

59. The method according to claim 57 or 58, wherein during the step of creating the angle β an angle α is introduced between the axis Y of the individual ingot and the X axis of the tubular body.

60. The method according to claim 49, wherein the step of mutually fastening the ingots (20) comprises the welding of two adjacent ingots along the edges of the contact side surfaces (27, 28) . , ,

61. The method according to claim 47, wherein the step of mutually fastening the ingots (20) comprises the mutual fitting of the ingots (20) , or the insertion of an outer rimming (14) .

62. Method according to claim 49, wherein the step of connecting the cooling channels (21) comprises the addition of a ring (16) on the rear portion of the tubular body (10) . 63. Method for manufacturing a cooled box (l) according to any claim 1 to 48, comprising the steps of:

- arranging a tubular body (10) according to any claim 49 to 62;

- arranging a shield (6) ; - fastening the tubular body (10) to the shield (6) .

64. The method according to the preceding claim, wherein the step of arranging the shield (6) comprises the step of cutting a quadrangular metallic plate (60) having a size suitable to close the opening formed in the furnace side wall.

65. The method according to claim 63 or 64, wherein the step of arranging the shield (6) comprises the step of making a hole in the plate (60) which is suitable to snugly house the tubular body (10) in the selected orientation.

66. The method according to any claim 63 to 65, further comprising the steps of arranging and fastening a protective pipe fitting (7) .

Description:

w Cooled box for positioning nozzles in arc furnaces"

[0001] . It is the object of the present invention a cooled box for the positioning of nozzles, such as burners, injectors and/or lances, within electric arc furnaces for founding steel .

[0002] . In the field of electric arc furnaces for steelmaking use, it is known to make openings in the side walls of the furnace chamber (or shaft) . Through such openings it is possible to introduce devices (or nozzles) such as auxiliary burners, injectors and/or lances. [0003] . Auxiliary burners allow adding further amounts of heat to the heat provided by the electric arc, in order to facilitate and speed up the founding of the metal bulk. By "injector" is commonly meant a fitting suitable to concomitantly inject gas and powder in the shaft. By "lance" is commonly meant an injector of the supersonic type. Injectors and lances, beside acting as gas injectors or burners, allow introducing additives useful to the metallurgic process in the molten metal bath, such as coal, lime or powders.

[0004] . Herein and below, auxiliary burners, injectors, and lances will be generally referred to as "nozzles" . [0005] . To the purpose of protecting these nozzles

against the temperatures found inside the furnace (1500 0 C - 1700 0 C), it is known to provide boxes which are cooled by means of an inner circulation of a fluid, particularly water. [0006]. A box of the known type is illustrated, for example, in Fig. 1 - 3.

[0007] . Such boxes are commonly made by casting a monolithic piece of copper. In the centre of the box a channel is located which is sloped and suitable to house the nozzle. The inclination of the channel allows directing the nozzle as much as possible towards the centre of the furnace.

[0008] . The boxes of the known type, although allowing introducing the nozzles within the furnace, are not without drawbacks.

[0009] . In fact, as the box is made as a monolith, great inner stresses arise which derive from thermal dilatations caused by the temperature reached inside the furnace. Thereby, the boxes of a known type are characterized by a very short working life (after a few weeks, they require extraordinary maintenance) , at the end of which cracking, flaws and wear phenomena will occur, which are such as to make the replacement of the box necessary. [0010] . Furthermore, casting the copper monolithic

block is a very complicated work, which requires a high specialization from the manufacturer, therefore involving high costs.

[0011] . In the end, given the monolithic block structure of the boxes of a known type, and given the position and size of the channel, the burner placement such that the flame is near to the bath, and directed thereto, is not possible. The channel conformation often determines a burner positioning such as to direct the flame at least partially towards the refractory material lining within the shaft. This causes the refractory early wear and imposes frequent maintenance activities on the furnace .

[0012] . It is the object of the present invention to provide a cooled box, which has such structural and functional features as to at least partially overcome the drawbacks mentioned with reference to the prior art.

[0013] . Particularly, it is the task of the present invention to provide a cooled box which is shaped such as to have a longer working life than the boxes of a known type.

[0014] . Particularly, it is the task of the present invention to provide a cooled box which can be produced through a simpler and less specialized process than the boxes of a known type.

[0015] . Particularly, it is the task of the present invention to provide a cooled box which allows placing the burner such that the flame is proximate to the bath and directed thereto. [0016] . This object and these tasks are achieved via a cooled box of the type described in claim 1. [0017] . Further embodiments will be described in the dependent claims . [0018] . Further features and advantages of the cooled box according to the invention will appear from the description set forth herein below of preferred exemplary embodiments thereof, which is given merely by way of non- limiting example with reference to the annexed Figures, in which: [0019] . Fig. 1 illustrates the section of an electric arc furnace of a known type;

[0020] . Fig. 2 illustrates a cooled box of a known type operatively placed within a furnace; [0021] . Fig. 3 illustrates a cooled box similar to the one of Figure 2, disassembled from the furnace;

[0022].. Fig. 4 schematically illustrates a perspective view of a cooled box in accordance with the invention; [0023] . Fig. 5 illustrates the detail of a furnace similar to the one designated with V in Fig. 1, comprising a cooled box in accordance with the invention;

[0024] . Fig. 6 illustrates a front view of the cooled ox in accordance with the invention;

[0025] . Pig. 7 illustrates a side view of the cooled box in accordance with the invention; [0026] . Fig. 8 illustrates a view of the section taken along the line VIII-VIII in Figure 6;

[0027]. Fig.- 9- illustrates a view of the -cooled box -in accordance with the invention similar to the one in Fig.

8, further comprising a nozzle; [0028] . Fig. 10 illustrates a plan view of a first step of processing an ingot suitable to manufacture the cooled box in accordance with the invention;

[0029] . Fig. 11 illustrates a view of the section taken along the line XI-XI in Figure 10; [0030] . Fig. 12 illustrates a view of the section taken along the line XII-XII in Figure 10;

[0031] . Fig. 13 illustrates three different views of a cap to be applied to the ingot in Figure 9;

[0032] . Fig. 14 illustrates a plan view of a second step of processing an ingot suitable to manufacture the cooled box in accordance with the invention;

[0033] ' . Fig. 15 illustrates a view of the section taken along the line XV-XV of Fig. 14;

[0034] . Fig. 16 illustrates a view of the section taken along the line XVI-XVI of Fig. 14;

[0035]. Fig. 17 illustrates a side view of a third step of processing an ingot suitable to manufacture the cooled box in accordance with the invention;

[0036] . Pig. 18 illustrates a front view of the ingot in Fig. 14;

[0037] . Fig. 19 illustrates a perspective view of a finished -ingot- suitable to manufacture the- cooled -box- in- accordance with the invention;

[0038] . Fig. 20 illustrates a perspective view of a finished ingot, similar to the one in Fig. 19;

[0039] . Fig. 21 illustrates a perspective view of a finished ingot, similar to the one in Fig. 18;

[0040] . Fig. 22 illustrates a front view of the assembled ingots during a first step of manufacturing the cooled box in accordance with the invention;

[0041] . Fig. 23 illustrates a front view of the assembled ingots during a second step of manufacturing the cooled box in accordance with the invention;

[0042] . Fig. 24 illustrates a different type of ingot in a view similar to the one in Fig. 11;

[0043] . Fig. 25 illustrates a different type of ingot in a view similar to the one in Fig. 11;

[0044] . Fig. 26 illustrates a different type of ingot in a view similar to the one in Fig. 11; [0045] . Fig. 27 illustrates an enlargement of the

detail designated with XXVII in Fig. 26;

[0046] ." Fig. 28 illustrates a view similar to the one in Fig. 22 of a first alternative embodiment of the tubular body according to the invention; [0047] . Fig. 29 illustrates a view similar to the one in Fig. 22 of a second alternative embodiment of the tubular"bodyaccording to the-invention;

[0048] . Fig. 30 illustrates a front view of the cooled box shield according to the invention; [0049] . Fig. 31 illustrates a view similar to the one in Fig. 7 of another embodiment of the cooled box according to the invention.

[0050] . With reference to the above-mentioned Figures, a cooled box (or simply "box") has been generally designated with 1. The cooled box 1 is located within an opening made in the side wall of an arc furnace 2 (see

Fig. 1) .

[0051]. In a manner known per se, the arc furnace 2 comprises a refractory material inner lining 3, a cooling system 4 and, upon operation, a molten metal bath 5.

[0052] . The cooled box 1 according to the invention comprises a tubular body 10. The tubular body 10 comprises, in turn, a plurality of bars or ingots 20 which are mutually fastened and arranged such as to be the side walls of the same tubular body.

[0053] . In accordance with the embodiment of the box 1 as represented in the Figures, the tubular body 10 defines an axis X.

[0054] . Particularly, the ingots 20 are arranged in the axis X direction (with the only exception being a small angle α described below) and are mutually juxtaposed along-contact—lines—and/or- sur-faces -being—also- arranged.. in the axial direction. Particularly, the ingots 20 are mutually fastened along junction lines also arranged in the axial direction. In other terms, the tubular body 10 of the cooled box 1 according to the invention comprises a circumferentially segmented structure.

[0055] . In accordance with the embodiment of the box 1 represented in the Figures, the ingots are arranged such as to form an approximately frusto-conical or frusto- pyramidal shape .

[0056] . In accordance with " an. embodiment, the ingots are arranged such that a longitudinal axis Y of each individual ingot is enclosed in a plane passing along the X-axis. The contact and/or junction surfaces between the ingots can also be enclosed in a plane passing along the X-axis.

[0057] . Particularly, the ingots are arranged such that a longitudinal axis Y of each individual ingot forms an angle α with the axis X having a width ranging between 1°

and 4°, preferably 2° (see Fig. 8 and 17) . [0058] . In accordance with other possible embodiments, the ingots can be arranged in different manners, for example such as to form an approximately cylindrical or prismatic shape. That is, the ingots can be arranged such that a longitudinal axis Y of each individual ingot is -parallel- to-the-ax-i-s—Xr

[0059] . In accordance with an embodiment, the tubular body 10 of box 1 comprises a channel 11 therein. Such a channel 11 is suitable to house a nozzle 30 of a type known per se.

[0060] . In the embodiment illustrated in the Figures, particularly in Fig. 22, the channel 11 has a regular decagon-shaped section. In accordance with other embodiments, and in order to meet particular contingent needs, the channel section can take other shapes, for example the shape of another, either regular or non- regular, polygon; a circumference; an ellipse; an V 8'; and the like. [0061], In accordance with an embodiment, the channel 11 has a diameter ranging between 100 and 400 mm, preferably between 120 and 250 mm.

[0062] . In accordance with an embodiment of the box 1 according to the invention, the ingots 20 comprise a channel 21 for the cooling fluid to circulate therein,

preferably for cooling water circulation.

[0063] . In accordance with the embodiment as represented in the Figures, the channel 21 of each ingot

20 is .substantially U-shaped, the arms of which run almost the whole length of the ingot. The two rectilinear and parallel conducts 211 and 212 being the U arms are

-joined-tø-eaeh-othe-r—by—a—^th-i-r-d—tr-ansvers al—conduct—213—

[0064] . The cooling channel 21 of each ingot is preferably connected to the cooling channels of the other ingots, such as to form an individual cooling circuit 12 running through the whole tubular body 10. [0065] . In accordance with the embodiment illustrated herein, the channel 21 of each ingot 20 is connected in series with the channels of the two ingots adjacent thereto, with the only exception being the first and the last ingots in the pathway. These latter channels are suitable to be connected to the feeding line and to the outflow line of the cooling fluid, respectively. [0066] . In accordance with other embodiments (not illustrated) , the individual channels are differently connected, for example according to an in-parallel scheme or according to a mixed in-series/parallel scheme. [0067] . A method to provide a tubular body 10 comprising a cooling circuit 12 according to the invention will be further described herein below.

[0068] . In accordance with the embodiment represented in the Figures (see, particularly, Fig. 19, 20, and 21) , each individual ingot 20 comprises a shoulder 23 on the side intended to be the inner wall of the tubular body 10. As " a consequence, the tubular body 10 comprises, inside the channel 11, a diaphragm 13 comprising all the -shoulders—2-3—of-al-1—the—i-ngot-s—20~

[0069] . In accordance with the embodiment represented in the Figures (see, particularly, Fig. 4, 6-9, and 30) , the box according to the invention further comprises a shield 6 and a protective pipe fitting 7.

[0070] . The shield 6 and the protective pipe fitting 7 allow completely closing a standard quadrangular-shaped opening obtained in the furnace side wall, while allowing any type of inclination of the tubular body 10.

[0071] . In the embodiments represented herein, the inclination of the axis X of the tubular body 10 relative to the shield 6 ranges between 30° and 60°, preferably it ranges between 40° and 50°. [0072] . In accordance with the embodiment represented in the Figures, the length of each ingot ranges between 350 and 550 mm, preferably between 420 and 480 mm. As it can be clearly seen in Fig. 7, 8, and 9, the usable length of the tubular body 10 in the whole is substantially equal to the length of the individual ingot

20 .

[0073] . The features of the cooled box 1 according to the invention described above, particularly the length and inclination of the tubular body 10, allow bringing the nozzles 30 to a highly reduced spacing from the molten metal bath. Particularly, when the nozzle 30 is a -bur-ne-r- 7 —th-ϊs—p-1-aeemenfe—a-l-løws—preserving—-the—r efractory- material coating 3 against the flame . [0074] . In accordance with an embodiment of the invention, the individual ingots 20 are made from a single block of copper.

[0075] . In accordance with other possible embodiments, the individual ingots 20 can be made from a single block of other material, adapted to be used at the temperatures which are characteristic of the furnace, such as steel, sinterized materials, for example ceramic materials (such as alumina, or aluminium oxide, Al 2 O 3 ) or so-called superalloys of the Inconel ® type (sold by Special Metals Corporation) or of the Hastelloy ® type (sold by Haynes International), or the like.

[0076] . In accordance with an embodiment of the invention, the individual ingots 20 are made from an individual monolithic block, as schematically shown in Fig. 11 and 15. [0077] . In accordance with other possible embodiments,

the individual ingots can be made in several pieces. [0078] . For example, the ingots can advantageously comprise a main body 22 and a "nose" 24. By "main body" 22 is meant that ingot portion which, in the operative configuration in which the box 1 is mounted and ready to operate, is nearest to the shield 6. The main body 22 is run-through--by—fche-eoo-1-ing—©hanne-l—^2-1- ^ -

[0079] . Instead, the nose 24 of the ingot 20 is that portion which, in the operative configuration in which the box 1 is mounted and ready to operate, is the most distant from the shield 6. The nose 24 is the ingot portion most exposed to wear. It is not run through by the cooling channel since, being particularly exposed to wear, liquid leakages could easily occur within the shaft .

[0080] . As schematically shown in Fig. 24, the ingot may comprise a nose 24 made of a material which is different from the one composing the main body 22. [0081] . As schematically shown in Fig. 25, the ingot may comprise a plating 25 of the nose 24, i.e. a covering of the nose 24 made with a layer of a material different from the one composing the main body 22 and the nose 24. [0082] . In what has been described above, both the ingot 20 main body 22, the nose 24, and the plating 25 can be made of copper, steel, ceramic material or

superalloy.

[0083] . In accordance with some possible embodiments, the nose 24 or the plating 25 of the individual ingot 20 are interchangeable, such as to be capable of being easily replaced during the working life of the box 1 without having to remove the main body 22 of the ingot 20 from—fche—tttbuiar—body—1-0 ^ -

[0084] . As schematically shown in Pig. 26 and 27, the ingots 20 may comprise a surface treatment 26 of the nose 24. This surface treatment can, for example, comprise an anti-wear material layer applied by plasma spraying.

Anti-wear materials are, for example, ceramic materials such as alumina (aluminium oxide, Al 2 O 3 ) and zirconia

(zirconium oxide, ZrO 2 ) . [0085] . As stated above, the tubular body 10 comprises a plurality of mutually fastened ingots 20. In accordance with the embodiment of Fig. 22, the ingots are mutually fastened by welding along their side surfaces.

[0086] . This kind of fastening between the ingots 20 originates a tubular body 10 capable of conjugating a high mechanical strength and the ability of undergoing thermal dilatations, without creating undue inner stresses. [0087] . In accordance with other possible embodiments, on the other hand, the ingots 20 are mutually fastened in

different manners. In Fig. 28, for example, a tubular body 10 is schematically illustrated in which the ingots 20 are mutually fastened by means of shape coupling, particularly through a dovetail. In Fig. 29 a tubular body 10 is instead schematically illustrated in which the ingots 20 are simply mutually juxtaposed and fastened through-an-~outer—r-immi-ng—1-4—

[0088] . These kinds of fastening among the ingots allow an easy disassembly of the tubular body 10, for example in order to replace a damaged or worn individual ingot 20. In the event that the ingots 20 are mutually welded, the tubular body 10 can however be disassembled by removing the welding seam. [0089] . In accordance with an embodiment, the box 1 further comprises a sealing ring 15 to seal any gap between the nozzle 30 and the channel 11, particularly between the nozzle and diaphragm 13. The sealing ring 15 avoids, that the flames within the furnace are canalized within any gap between the nozzle 30 and the diaphragm 13 and that therefore dangerously come back along the channel 11.

[0090] . The sealing ring 15 is made of a material suitable to create a barrier resistant to the operative temperatures which are characteristic of the inside of the arc furnace (1500-1700 0 C) . A material having these

features can, for example, be obtained from ceramic fibers, glass fibers, steel fibers, or the like. The fibers can be mutually braided, weaved or packed to form a mat . [0091] . As stated above, the tubular body 10 comprises a cooling circuit 12 running therethrough, thus allowing exposure—to—t-he—furnace-wor-king—temperatures-. [0092] . The cooling circuit 12 comprises, as stated above, the set of the cooling channels 21 of ingots 20. Furthermore, the cooling circuit 12 comprises a ring 16 which is suitable to connect the individual cooling channels 21 of the ingots 20.

[0093]. The ring 16, as illustrated in Fig. 23, is particularly suitable to create a passageway which allows the fluid exiting from an ingot channel to be directed in the next ingot channel. Therefore, the ring 16 is suitable to connect in series the individual cooling channels 21. [0094] . In accordance with other embodiments (not illustrated) , the ring 16 is suitable to differently connect the individual channels 21, for example according to an in-parallel scheme, or according to a mixed in series/parallel scheme. [0095] . The cooling circuit is completed by two hoses 17 and 18 for connecting the circuit 12 to the feeding

and outflow lines of the cooling fluid.

[0096] . A method for providing a cooled box 1 according to the invention will be described below.

[0097] . The method for manufacturing the cooled box 1 first comprises providing the tubular body 10. Therefore, a method for providing the tubular body 10 according to -the—±nvention—-wi-1-1—be—f-i-rst described—below—-Such—a. method comprises the steps of:

- providing a plurality of ingots 20; - creating a cooling channel 21 within each ingot 20;

- mutually fastening the ingots 20 by arranging them in an arrangement such as to form the side walls of the tubular body 10;

- connecting the individual cooling channels 21 such as to form an individual cooling circuit 12.

[0098] . In accordance with an embodiment of the above- described method according, .to the invention, the arrangement of the ingots comprises the step of drawing the material, particularly copper. [0099] . In accordance with other possible embodiments, the arrangement of the ingots may comprise a sintering step (for materials such as ceramics and superalloys) , or a casting and/or moulding step (for materials such as copper and steel) . [00100] . In accordance with an embodiment of the method

according to the invention, the arrangement of an individual ingot comprises a step of applying a shoulder 23 (see Fig. 14 and 15) , for example by welding. [00101] . In accordance with an embodiment of the method according to the invention, the arrangement of the ingots 20 comprises arranging two special ingots (see Fig. 20 and—21-)—which—are-intended—to—be—locafeed-as-th e-first-and- last of the series, respectively. These ingots have an appendix which allows extending one of the two conducts 211 and 212, respectively. In Fig. 22 and 23, it can be seen that these ingots are intended to house the hoses 17 and 18.

[00102] . In accordance with an embodiment of the method according to the invention, the creation of a cooling channel 21 within each ingot 20 comprises a double step of longitudinal deep drilling of the ingot 20. Thereby, two conducts 211 and 212 are produced which are rectilinear and parallel relative to each other. [00103] . A further milling step provides the third conduct 213 transversal to the first two (Fig. 10 to 12) . The cooling channel 21 is completed by the insertion of a cap 214 (Fig. 13) suitable to restore the sealing of channel 21 at the milling (Fig. 14 to 16) . The cap 214 can, for example, be locked in situ by welding. [00104] . In accordance with an embodiment of the method

according to the invention, the arrangement of n ingots provides for the creation of two contact side surfaces 27 and 28 which form, relative to each other, a 360°/n wide angle β (see Pig. 18) . This operation can be obtained, for example, by machine tooling. The thus-obtained side surfaces 27 and 28 are intended to contact the -corresponding~side-sur~faces of—the-ad-jacent-ingots. [00105] . During the step of creating the angle JB, an optional angle α can be also introduced between the axis F of the individual ingot and the axis X of the tubular body (see Fig. 17) . In this manner, a tubular body 10 is obtained which has a frusto-conical or frusto-pyramidal shape. Instead, if the angle α is maintained null, a tubular body 10 is obtained which has a cylindrical or prismatic shape.

[00106] . In accordance with an alternative embodiment of the method, the step of arranging the individual ingot 20, for example by sintering or casting, can already comprise other steps separately described above. In a so- called net-shape approach, the step of arranging the individual ingot 20 can, for example, comprise the steps of arranging the cooling channel, side surfaces 27 and 28, and relative angles α and β, arranging the shoulder 23, etc. Such an embodiment of the net-shape method complicates the manufacturing step of the ingot 20, but

sharply ' reduces the total number of steps of the method. [00107]. In accordance with an embodiment of the method according to the invention, the step of mutually fastening the ingots 20 comprises welding an ingot to the adjacent ingot along the edges of the contact side surfaces 27 and 28, respectively.

- [00108]——-In—accordance- with— other—possible—embodiments- of the method according to the invention, the step of mutually fastening the ingots 20 may comprise mutually joining the ingots, (for example by means of a dovetail joint) or the insertion of an outer rimming. [00109]. In accordance with an embodiment of the method according to the invention, the step of connecting the individual cooling channels 21 to form an individual cooling circuit 12 comprises the addition of a ring 16 to the rear portion of the tubular body 10.

[00110] . The method for providing the cooled box 1 according to the invention comprises the steps of:

- producing the tubular body 10 (see above) ; - providing the shield 6;

- fastening the tubular body 10 and the shield 6 to each other such as to form the cooled box 1.

[00111] . In accordance with an embodiment of the method according to the present invention, the step of arranging the shield comprises the steps of cutting a quadrangular

metallic plate 60 having a size suitable to close the opening made in the furnace side wall. In the quadrangular metallic plate 60, a hole is required to be made having such a shape and size as to snugly accommodate the tubular body 10 in the selected orientation (see Fig. 30) .

[00112]-.-—In- accordance- with- - an- embodiment,- -the— method, for providing the cooled box 1 also comprises the steps of providing and fastening the protective pipe fitting 7. The protective pipe fitting 7 has the purpose of closing the space that has been left opened between the shield 6 and the tubular body IQ . The use of this protective pipe fitting allows carrying out a tubular body 10 consisting of ingots of an individual length. The use of this protective pipe fitting further allows inclining the tubular body relative to the shield 6 as desired. [00113] . Alternatively, greatly complicating the method, ingots 20 having variable lengths could be produced, such as to obtain a snug adhesion of the shield 6 to the tubular body 10, despite the inclination of the latter. Such an embodiment is schematically illustrated in Fig. 31.

[00114-] . In the light ' of what has been described above, it will be understood by those skilled in the art that the particular circumferentially segmented structure of

the tubular body 10 allows to the same body to dilate and shrink following temperature-induced deformations, without that, for this, crackings or flaws occur in the metallic mass . [00115] . The above-described structure of the tubular body 10 can, in fact, be compared to an isostatic structure—in-- which —the- -dilatations—imposed— by——£he- temperature do not induce high stress states . On the contrary, the monolithic block structure of the conventional type can without doubt be compared to a highly hyperstatic structure in which a dilatation imposed by the temperature necessarily induces also potentially very high stress states.

[00116] . Furthermore, the method for manufacturing the cooled box 1 according to the invention can be carried . out through a sequence of technologically simple steps (drawing, drilling, milling, welding, etc.), without having to employ complex and costly technologies, such as casting. [00117] . The particular conformation of the cooling channels 21 can allow, if required, to extend the drilling so as to open the conduct 211 or 212 on the ingot nose 24. This possibility allows for the insertion of a further nozzle having a reduced size to be flanked to the main nozzle 30. Relative to a diameter of channel

11 of about 200 mm, the diameter of conduct 211 or 212 is about 20 mm.

[00118] . In accordance with a possible embodiment, the ingot intended to accommodate the auxiliary nozzle is of larger dimensions than the other ingots 30. An auxiliary conduct having a diameter higher than the conducts 211 or -2-12—can—thus—be-obta-i-ned- T —such—as—to-accommodate-a- nozzle- having a diameter as large as 35 mm, or more. [00119] . The cooled box 1 according to the invention, due to the particular conformation thereof, allows for an efficient protection, both thermal and mechanical, of the nozzles 30.

[00120] . The particular structure of the cooled box 1 according to the invention allows bringing the nozzles 30 very near to . the molten metal bath, and thus allows improving the nozzles efficacy. Particularly, the burner efficiency takes great advantage from the fact that it is located near the bath and oriented thereto. This placement further preserves the refractory coating from early wear. If, on the other hand, as in the prior art solution, the burner is located spaced from the bath and is incorrectly oriented, it loses efficacy and determinates a substantial wear of the refractory. [00121] . The increased rise towards the inside of the furnace must necessarily be accompanied by an increased

mechanical strength. In fact, while the metallic material is loaded inside the furnace, the risk that impacts occur on the nose of the tubular body 10 is high. The particular structure of the box 1 according to the invention proved to be extremely solid, such as to absorb the metallic material impacts without experiencing

-relevant damages-.-

[00122] . Furthermore, in the case where a particularly violent impact damages the tubular body, the damage will be easily repairable by replacing only the damages ingots .

[00123] . The cooled box structure according to the invention further allows reducing by about 50% of the metallic mass employed as compared with the monolithic block structure of the cooled boxes of a conventional type, and kept any other features unchanged. [00124] . It is clear that variations and/or additions to what has been described and illustrated above may be provided. [00125] . Generally, all the features described above with relation to specific possible embodiments can be carried out independently from each other.

[00126] . To the embodiments of the cooled box 1 described above, those skilled in the art, aiming at meeting contingent and specific needs, will be able to

carry out a number of modifications, adaptations, and replacements of elements with others being functionally equivalent, however, without departing from the scope of the following claims.