Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B7/00—Blast furnaces
  • C21B7/08—Top armourings

Definitions

• the present invention relates to throat armour for a blast furnace.
• throat armour In a blast furnace, the use of throat armour to protect the outer shielding of the furnace above the charge against wear due to the raw materials loaded through the throat has long been known.
• this throat armour was merely formed with refractory bricks. Such refractory bricks are, however, not very resistant to wear. Since then, many methods have been developed to increase the working life of the throat armour.
• throat armour is nowadays formed using pig iron or cast steel shielding bricks.
• These shielding bricks which are much smaller in size than the shielding plates, are overlapped in large numbers over several rows and fixed to the outer shielding of the blast furnace.
• they form a smooth impact surface inside the furnace.
• each brick is dish-shaped.
• These dish-shaped bricks make it possible to form throat armour whose impact surface comprises material-retaining pockets.
• throat armour is new, its material-retaining pockets are filled with a concrete having a good wear resistance. This wear-resistant concrete then forms the majority of the impact surface and thus reduces the exposure of the metallic bricks to wear.
• Throat armour formed with dish-shaped bricks has an acceptable working life, but the fixing of the bricks to the outer shielding is complicated and the installation of the throat armour consequently takes a considerable time.
• annular segments of the throat armour may be pre- assembled in the workshop. These pre-assembled segments comprise a metallic supporting plate on to which the metallic bricks are individually fixed. In order to install the throat armour in the furnace, it is then sufficient to fix the pre- assembled ring segments to the outer shielding of the furnace. However, even though the time taken for installation inside the furnace is thus greatly reduced, it should still be noted that the assembly of a segment of such throat armour in the workshop is far from simple. Another weakness of this type of throat armour originates from the large number of fixing elements required to fix the shielding bricks.
• the objective of the present invention is to propose throat armour for a blast furnace which may be more easily installed, while having a working life that is comparable with, if not longer than, that of throat armour formed using pig iron or cast steel bricks.
• the protective elements are no longer bricks but nodular graphite cast iron plates.
• the present invention has in effect the merit of having noticed that throat armour formed with nodular graphite cast iron plates may attain a working life comparable with, if not longer than, throat armour formed using pig iron or cast steel bricks, with two conditions: (1) the plates are provided with superimposed rows of material- retaining pockets; and (2) the plates are provided with an internal cooling circuit behind said rows of material-retaining pockets. Because of the existence of these pockets, the plates have an excellent wear resistance with a weight that is considerably less than that of solid plates.
• the rear part of the plate forms, in spite of a reduced thickness, a support for the pockets which is distinguished by excellent stability in shape and high mechanical strength over time.
• the cooling of the plates also protects their fixing elements against overheating that could affect their mechanical strength.
• approximately two thirds of the thickness of a plate are formed by material-retaining pockets, while the rest of the thickness of the plate forms a solid plate in which the internal cooling circuit is arranged.
• the plates may be fixed to the outer shielding by means of threaded rods.
• Fixing elements such as internally threaded bushes, are also advantageously anchored in the cooled rear part of the plate, which guarantees their strength over time.
• the pockets are advantageously filled with a concrete having a good wear resistance. At least at the start of a blast furnace campaign, this wear- resistant concrete then forms the major part of the impact surface. As the wear- resistant concrete in the pockets wears away, said pockets are filled with charge material, which thus takes on the protective function of the initial wear- resistant concrete.
• the internal cooling circuit is preferably cast in the plate. It may for example have a serpentine path or may comprise parallel vertical channels extending between two horizontal collectors.
• the pockets have access openings in the impact surface of the throat armour, said openings penetrating the thickness of the plate obliquely, preferably making an angle between 30° and 50° with the vertical.
• Such an inclination of the pockets promotes the retention of the wear- resistant concrete or the charge material in the pockets.
• the lower edge of the opening of a pocket is advantageously formed by a vertical shoulder in order to promote still further the retention of the wear-resistant concrete or the charge material in the pockets.
• the material-retaining pockets of an uppermost row preferably have access openings in the upper end surface of the plate.
• the throat armour then comprises two superimposed plates, the upper plate has its lower edge bevelled, so as to give access to the pockets of the uppermost row of the lower plate. In this way, an excellent protection of the two superimposed plates is achieved at the level of their common joint.
• Figure 1 a three-dimensional view showing the rear face of a segment of throat armour of a blast furnace
• Figure 2 a three-dimensional view showing the front face of the segment of Figure 1 ;
• Figure 3 an elevation of the segment of Figure 1 , showing the front face
• Figure 4 a side elevation of the segment of Figure 1.
• FIGs 1 to 4 show an annular segment 10 of the throat armour of a blast furnace, which serves to protect the outer shielding of the furnace above the charge against wear by the raw materials loaded through the throat.
• These annular segments 10 are arranged side by side so as to form a continuous ring at the level of the blast furnace throat.
• a segment 10 may have, for example, a height of about 5 m and a width of about 1.0 m, so that the throat armour will be formed by some thirty segments 10 as shown in the figures.
• the segment 10 consists of two superimposed plates 12, 12'.
• Each plate 12, 12' comprises a rear surface 14, 14', which faces the outer shielding of the blast furnace, a front surface 16, 16', which is oriented towards the inside of the blast furnace and acts as the impact surface, two side surfaces 18, 20, 18', 20', an upper end 22, 22' and a lower end 24, 24'.
• the rear surface 14, 14' advantageously has a shape that matches the shape of the inner surface of the outer shielding at the place where it is fixed (see in particular the rear surface 14' of the lower plate 12' in Figure 4).
• Each plate 12, 12' is individually fixed to the outer shielding of the blast furnace. It can be seen in Figures 1 to 4 that, in the back 14, 14' of each plate 12, 12', four bushes 26, 26' are anchored, each provided with an internal thread. Into these bushes 26, 26' are screwed threaded rods (not shown) which are used to fix the plates 12, 12' to the outer shielding (not shown). Sealing is achieved by sealing caps (not shown) welded to the outer shielding.
• the plates 12, 12' are moulded plates made of nodular graphite cast iron. In order to guarantee their stability in shape and their mechanical strength over time, they are provided with an internal cooling circuit. It can be seen in Figure 3 that a plate 12, 12' comprises two serpentine channels whose path is shown by the broken lines 28, 30 or 28', 30'. It can be seen in Figure 4 that these channels are formed by pipes 32, 32', which are cast in the plate 12, 12' near the rear surface 14, 14'. The ends of these pipes 32, 32' emerge from the rear surface 14, 14' of the plate 12, 12' and form the connecting pipes 34, 36 and 34', 36'. Said connecting pipes emerge imperviously through the outer shielding where they enable the plates 12, 12' to be integrated into a cooling system of the blast furnace. The imperviousness of the passage of the connections 34, 34', 36, 36' into the outer shielding is achieved, for example, by means of sealing sleeves and/or expansion joints connected between each connector 34, 34', 36, 36' and the outer shielding.
• Each plate 12, 12' comprises, on the side of its front surface 16, 16', several rows of material-retaining pockets 40, 40' (see for example Figure 2).
• These material-retaining pockets 40, 40' have access openings in the front surface 16, 16' of the plate 12, 12' and penetrate the thickness of said plate obliquely, making an angle of approximately 40° with the vertical (see Figure 4).
• Vertical partitions 42, 42' delimit the pockets 40, 40' of a given row.
• the lower edge of the opening of a material-retaining pocket 40, 40' is advantageously formed by a vertical shoulder 44, 44' (see for example Figure 2).
• the dotted areas in the pockets 40, 40', 46, 46' represent a concrete 50 with a good wear resistance, which fills the pockets 40, 40', 46, 46' at least at the beginning of a blast furnace campaign.
• This wear-resistant concrete 50 then forms more than three quarters of the impact surface 16, 16' of a plate 12, 12' and thus reduces the exposure of said plate to wear.
• said pockets become filled with charge material, which thus takes on the protective function of the initial wear-resistant concrete. It remains to point out that the inclination of the pockets 40, 40', 46, 46' and the vertical shoulders 44, 44' promote the retention of the wear-resistant concrete or the charge material in the pockets 40, 40', 46, 46'.
• the cooling circuit also has a beneficial effect on the wear resistance of the concrete in the material-retaining pockets and it promotes the deposition of the charge materials replacing the wear-resistant concrete at the end of the campaign.
• the working life of the throat armour as described above may be estimated as equivalent to at least one blast furnace campaign, i.e. as at least 15 years.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Blast Furnaces (AREA)
• Aiming, Guidance, Guns With A Light Source, Armor, Camouflage, And Targets (AREA)
• Furnace Housings, Linings, Walls, And Ceilings (AREA)

Applications Claiming Priority (3)

Publications (2)

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ID=19731936

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• 2000
  • 2000-10-04 LU LU90649A patent/LU90649B1/fr active
  • 2000-12-15 TW TW089126856A patent/TW448283B/zh not_active IP Right Cessation
• 2001
  • 2001-09-24 EP EP01969764A patent/EP1330554B1/de not_active Expired - Lifetime
  • 2001-09-24 AT AT01969764T patent/ATE263256T1/de active
  • 2001-09-24 AR ARP010104476A patent/AR030793A1/es active IP Right Grant
  • 2001-09-24 DE DE60102598T patent/DE60102598T2/de not_active Expired - Lifetime
  • 2001-09-24 AU AU2001289915A patent/AU2001289915A1/en not_active Abandoned
  • 2001-09-24 WO PCT/EP2001/011030 patent/WO2002029122A1/en active IP Right Grant
  • 2001-09-24 CZ CZ20030938A patent/CZ298922B6/cs not_active IP Right Cessation

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