FR2588069A1 - PROCESS FOR IGNITING A BED OF ORE FOR ITS AGGLOMERATION - Google Patents

Abstract

THE SUBJECT OF THE PRESENT INVENTION IS A PROCESS FOR IGNITING A BED OF ORE WITH A VIEW OF ITS AGGLOMERATION, IN WHICH A MIXTURE OF SOLID FUEL AND ORE IS HOT-FRITTED, THE MIXTURE FORMING A BED 29 IN CONTINUOUS HORIZONTAL MOVEMENT UNDER A OVEN CALLED IGNITION HOOD, SUCTION BEING MADE UNDER THE BED, THE OVEN BEING HEATED BY THE BURNERS 15. ACCORDING TO THE INVENTION, THE BURNERS ARE ARRANGED ABOVE THE BED AND DIRECTED TOWARDS THE BED, THE SPINKS 31 OF THE BURNERS ARE APPROACHED ON THE UPPER PART OF THE BED TO BE AGGLOMERATED BY ADJUSTING THE ALTITUDE AND ANGULAR SO AS TO GENERATE SECANT AND INCANDESCENT CIRCULAR OR ELLIPTICAL SURFACES ON THE BED.

Description

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  The subject of the present invention is a process

  ignition of a bed of ore for its agglomeration

  tion. It is known that this operation consists in sintering hot a mixture of solid fuel and ore, for example coke dust and iron ore,

  in view of the agglomeration of the latter, for him

  put to resist crushing in the blast furnace loads. The industrial plant usually has a continuous grid moving slowly

  o10 horizontally under an oven called an ignition hood.

  The ignition, made by the hood is intended to wear

  the upper part of the mixture to be agglomerated at a time

  sufficient to ensure the maintenance of his

  bustion. Thanks to an aspiration carried out under the grid,

  this reaction makes it possible to obtain the drying, dehydration and

  and decarbonization of the lower part of this layer. Usually, the height of the vault is of the order of one meter, and does not fall below 700mm. Burners located in the hood, on the top

  the bed to be agglomerated ensure thermal and direct

  gent towards the oxidation air bed warmed up in the

  flame. Indeed, agglomeration on a grid of mines

  rais is a process which requires a thermal input obtained: - on the one hand, by the combustion of gaseous or liquid fuels in the burners of the fume hood,

  - on the other hand, by burning solid fuels

  constituting the mixture deposited on the grid.

  The search for savings on the cost of these thermal inputs and the improvement of the ignition conditions to increase the quality of the agglomerate have led

  to present the present invention.

  So far, the burners are placed at a

  fixed and are fixed to heat the furnace atmosphere, whose vault radiates to heat the layer

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slow moving.

  In accordance with the present invention, by a

  altitude and angularity of the ignition burners,

  the sting of these is approached on the upper part.

  bed to be sintered, so as to generate surfaces

  Circular or elliptical intersecting and incandescent.

  The burners, placed side by side, are arranged

  transversely to the movement of the bed, in one or more

  sieurs rangées. Each row of burners is arranged

  on a mechanical device for angular adjustment with

  vertically, allowing to adjust the angle of

  squats darts while another mechanical device sets the distance of the burners from the surface

upper bed to agglomerate.

  Other features of the invention appear

  will be in the following description given

  by way of non-limiting example with reference to the accompanying drawings, and which will make it clear how the invention

can be realized.

  Figure 1 is a top plan view of an installation for the application of the method according to the present invention; Figure 2 is a longitudinal sectional view of said installation, along the line A-A of Figure 3; Figure 3 is a cross-sectional view of the plant along the line B-B of Figure 2, and Figure 4 is a schematic view showing

  a burner placed opposite the agglomerate layer

  Mérer. The installation shown in the Figures comprises for example three rows of burners each fed for example by a natural gas collector 11a, 11b, 11c,

  a steel gas collector 12a, 12b, 12c and a collector

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  13a, 13b, 13c, connected to respective distributor lines 11,12,13. For each row of burners, one of the collectors can act as a support beam and have a suitable section, for example square (12a, 12b, 12c). This beam, to which the burners 15 are fixed on each row, is supported by screw jacks 16,

  16 'which allow to adjust the altitude of all

  theirs simultaneously. The cylinders are supported on the

  frame of the hood. Glances 17 are planned through

  to the refractory 18 to allow observation and

  monitoring the operation of the burners.

  The lower part of each burner forms a parallelepiped block 21 with rectangular section or

  square whose lower face 21a, according to a

  Advantageous feature of the present invention is a radiation surface. This face 21a is raised in temperature to radiate on the bed to be agglomerated, thus creating an ignition shaft. The geometry of this radiating face can be concave, with the heart of the flame placed at the optical center. Where appropriate, this

  face can be heated by small burners

iliary.

  The blocks 21 are arranged against each other

  very, to form a continuous line. The inferior faces

  21a burners are located projecting from the bottom surface 23 of the vault of the hood (taking into account a possible vertical movement for adjusting the position of the flames of the burners:

  depending on the setting, they can be level or

deny back).

  According to the method of the present invention, the lower face 21a of the burners is located at a distance of between about 20 and 30 cm above the layer to be agglomerated (instead of 70 to 100 according to conventional methods). This short distance allows

  particularly the heating of the bed to be agglomerated by

  the lower side of the burners.

  For example, a weather sensor has been

25.

  Figure 4 shows schematically a burner inclined at an angle α on the vertical, to be oriented towards the material to be agglomerated which approaches it, as indicated by the arrow F in this Figure. The angle a will advantageously be between 0 and 30. The burner is adjustable by means of a ball-and-socket system 26 housed in the refractory 18 of the fume hood. The burner comprises a fuel inlet 27 and an air inlet 28. Its lower face 21a is at a height L (20 to 30 cm) above the bed to be agglomerated 29. The tip of the sting 31 of the flame is established on the bed to define a circular or elliptical section of dimension S, such that the sections of two adjacent burners are

cover on their edges.

  The burners can thus go up or down, and tilt in the plane of movement of the bed. The aim is to obtain the optimum impact of the sting

  burners to ensure the most perfect combustion pos-

  from the upper side of the bed, reducing the

  parasitic thermal losses to the atmosphere of the

boratory oven and walls.

  The mechanical adjustments can be ordered from

  tomatically according to various parameters, such as the speed of the bed, the height of the layer,

  the nature of the ore and the fuel used.

  In addition to their traditional function of providing the necessary calories, the burners bring the reaction oxygen into the layer by the air which is heated during its passage in the burners. The excess air can be adjusted to a value of 45 to 50%, for example of the amount necessary for a complete combustion of

  fuel injected by the burners.

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  It goes without saying that the described and illustrated embodiment is only an example, and that it can be

  modified in particular by substituting

nomic.

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Claims (10)

claims   1. A process for igniting an ore bed for agglomeration, in which a mixture is sintered hot   of solid fuel and ore, the mixture of   mantle a bed (29) in continuous horizontal movement under an oven called an ignition hood, an aspiration being   made under the bed, the oven being heated by brigs their (15),   characterized in that the burners are arranged   above the bed and directed towards it, the darts (31) of the burners are approached on the upper part of the bed to be agglomerated by an adjustment in altitude and angular, so as to generate on the bed circular surfaces   or elliptical secant and incandescent.   2. Method according to claim 1, characterized in that the burners (15) are placed side by side, transversely to the displacement of the bed, on at least one row.   3. Method according to claim 2,   characterized in that the burners are fixed to a collector   fuel or air supply (12), dis-   laid horizontally andforming beam support burner. 4. Method according to claim 3, characterized in that the beam (12) is supported by   cylinders (16) adjustable in height.   5. Method according to one of claims 2 or 4,   characterized in that the lower portions (21):   burners have a rectangular section.   6. Method according to one of the preceding claims,   characterized in that the lower faces (21a) of the burners are heated to radiate on   the bed to be agglomerated (29), thus creating a votin d'al- Lumage. 7-2588069   7. Process according to claim 6,   characterized in that the radiating face (21a) of each   that burner is a concave surface, with the heart of   the flame placed at the optical center of the surface.   8. Method according to one of claims 6 or 7,   characterized in that the lower faces (21a) of the   burners are heated by auxiliary burners.   9. Method according to one of the preceding claims,   characterized in that the burners can be inclined with respect to the vertical, at an angle of between 0 and 30, so as to direct the flame towards the material   the bed (29) that approaches the flame.   10. Method according to one of the preceding claims,   characterized in that the burners (15) are at a   distance of the order of 20 to 30 cm from the bed to be agglomerated (29).