LU88425A1 - Device for distributing granular materials loaded on an agglomeration strip of ores - Google Patents

Description

Device for distributing granular materials loaded on an agglomeration strip of ores.

The present invention relates to a device for distributing granular materials loaded onto an agglomeration strip of ores, with a view in particular to ensuring vertical segregation within these materials.

The description which follows will refer more specifically to the agglomeration of iron ores. It goes without saying, however, that the invention is also applicable to the agglomeration of other ores, and even of other materials, capable of being treated under analogous conditions.

The iron ore strip agglomeration process has been known for a long time and is widely used around the world. It essentially consists of depositing on a moving strip a charge consisting essentially of a mixture of iron ores and fuel, generally coke dust, igniting this charge on its upper surface and sucking in air through the charge to advance combustion over the entire thickness of the layer formed by the charge on the strip. At the end of the operation, an agglomerated cake is obtained which, after crushing and screening, constitutes a quality charge for the blast furnace.

It is known that the materials loaded on an agglomeration strip usually consist of a mixture of granules of different sizes, ranging for example from "less than 2 mm" to "more than 8 mm". Each granule contains mainly particles of ores and coke; generally, large pellets have a lower proportion of fuel than small pellets. Experience has shown that it is advantageous to have the fine fraction of the mixture in the upper part of the layer of materials deposited on the agglomeration strip, and the larger fraction in the lower part of this same layer. This arrangement, known as vertical segregation, facilitates the ignition and agglomeration of the upper part of the charge, which is richer in fuel; it also improves the gas permeability of the rest of the charge by increasing its vacuum index, which promotes agglomeration proper.

Furthermore, it is sometimes desirable to operate a so-called transverse load segregation, to compensate for a lack of homogeneity which can lead to an irregular quality of the agglomerate produced. This lack of homogeneity can in fact give rise to a greater permeability of the load and to higher thermal losses in the lateral zones of the load.

Currently, the load to be agglomerated is generally deposited on the strip by means of a feed hopper provided, at its lower outlet orifice, with a roller which ensures the distribution of the load over the width of the strip. This device is installed above the initial part of the strip. It does not allow vertical segregation, or possibly transverse segregation, desired within the load.

The first object of the present invention is to propose a device which, in combination with a conventional loading installation, makes it possible to ensure the required vertical segregation of the materials, when these are deposited on the strip.

An additional object of the invention is to propose an additional device making it possible to carry out in addition a transverse segregation of these materials.

In accordance with the present invention, a device for distributing the granular materials loaded on an ore agglomeration strip, which comprises a feed hopper situated above the initial part of the strip, a load distribution roller arranged under said hopper and extending transversely across the width of the strip as well as a material layer equalization blade, is characterized in that it comprises, between said distribution roller and the upper surface of the strip, at least a plurality of parallel deflection elements oriented perpendicular to the axis of said distribution roller and distributed over the width of the strip, in that the distance between two neighboring deflection elements belonging to the same plurality of elements is chosen so as to allow the granules whose size is less than or equal to a predetermined dimension to pass and to deflect the granules whose size is greater than said predetermined dimension, and in that said deflection elements are, at least in part, inclined downward in the direction opposite to the direction of movement of said strip.

Within the same plurality of deflection elements, the distance between two neighboring elements can be constant; it can however also vary in any appropriate way, in particular to modulate the segregation operated by the present device along the width of the strip.

According to a particular embodiment, said deflection elements belonging to the same plurality can be constituted by bars which are arranged in a sheet and thus form a grid inclined upstream of the agglomeration strip. One can have one above the other several grids having between their respective bars of distances adapted to the size of the granules that each of the grids must deviate. In this case, this distance decreases from the upper grid to the lower grid.

The aforementioned deflection elements can also consist of plates, preferably vertical, the upper part of which is sliced obliquely and is thus inclined upstream of the agglomeration strip. The set of upper edges of these plates forms the deflection grid for the largest granules. Between these plates, one can have other series of plates parallel to the first and having decreasing spacings. Each of the plates of these additional series has an inclined upper edge, preferably parallel to that of the first plates. The inclined upper edges of any series of plates are arranged lower than those of the series of plates having a greater spacing.

According to another characteristic, said deflection elements are mobile; they are preferably bodies of revolution which rotate about an axis parallel to the axis of said distribution roller.

In particular, said deflection elements may consist of discs mounted on a shaft parallel to the axis of the distribution roller. Several series of discs can be installed, the diameter and preferably also the spacing remain constant in the same series, but vary from one series to another. The least spaced discs are also the ones with the smallest diameter.

These discs are advantageously perforated, and if necessary, reduced to rings, in order to reduce the weight of the device. It goes without saying that the recesses in the discs must not compromise, even locally, the spacing provided between two neighboring discs.

The device of the invention may also include deflection means, adapted to the deflection elements of the granules which have just been described.

These deflection means are generally constituted by plates, arranged at the outlet of the deflection elements and upstream of them relative to the direction of movement of the agglomeration strip. These plates are tilted up and down; they extend on the one hand to the immediate proximity of the elements to which they are adapted, and on the other hand to the region of the strip which must receive the granules coming from the corresponding deflection elements.

Where appropriate, and in particular with the disc-shaped rotating deflection elements, said plates may have notches at their upper edge, so that they can be inserted between these rotating elements. This arrangement also has the advantage that said plates form combs, the teeth of which unclog the. device, due to the rotation of said deflection elements.

According to another advantageous characteristic, said deflection means may comprise lateral guides, for directing the granules towards one or more zones of the width of the strip and thus effecting transverse segregation combined with vertical segregation. These lateral guides can also be articulated, so as to be able to modify the transverse segregation of the load.

Alternatively, such lateral guides can be mounted on the deflection grids which have been described above.

In combination with the aforementioned deflection means, the device can include a distribution device, which makes it possible to carry out crossed flows of material and thus to act on the segregation of the load.

The device of the invention may also include an inlet deflector, disposed between the distribution roller and the elements for deflecting the granules. This deflector is intended to receive the load coming from the distribution roller and to direct it towards the deflection elements; it can also help to improve the transverse distribution of the load.

The device of the invention may also include means for adjusting the thickness of at least one of the layers of granules deposited on the strip. These means may in particular comprise at least one generally inclined blade, arranged transversely relative to the strip and advantageously fixed to the lower end of the corresponding outlet deflector. This blade can be profiled so as to give any particular shape desired to the upper surface of the corresponding layer of material.

It may finally be advantageous for the device of the invention to be provided with means for shaking, respectively for vibrating said deflection elements, individually or in groups, continuously or intermittently, to prevent clogging of the device.

We will now describe in more detail some exemplary embodiments of the invention, with reference to the accompanying drawings, in which FIG. 1 is a perspective view illustrating a first variant of the device of the invention, the deflection elements of which are fixed; Fig. 2 is a view in longitudinal section of the device shown in FIG. 1; Fig. 3 is a perspective view illustrating a second variant of the device of the invention, the deflection elements of which are mobile; Fig. 4 is a view in longitudinal section of the device shown in FIG. 3; Fig. 5 is a plan view showing the position of inlet and outlet deflectors in a device of FIG. 3; Fig. 6 shows a view in longitudinal section of another variant of a device with movable deflection elements; and Fig. 7 shows outlet deflectors provided with lateral guides to operate a transverse load segregation.

These figures constitute schematic representations, where we have not reproduced the elements which are not essential for a good understanding of the invention. Identical or analogous elements are designated by the same reference numerals in all the figures.

Fig. 1 illustrates, in a perspective view, a first variant of the device of the invention, in which the deflection elements are fixed.

A conventional installation for loading an agglomeration strip essentially consists of a feed hopper 1, which contains the mixture to be agglomerated, of a distribution roller 2, which ensures that the load is distributed as evenly as possible. on the agglomeration strip 3, and an equalizing blade 4, which levels the load.

According to the invention, between the distribution roller 2 and the strip 3 is installed a device, generally designated by the reference numeral 5, which is intended to operate the vertical segregation of the load on the strip.

The device 5 shown here allows segregation into three superimposed layers. This arrangement is of course only described by way of simple example and has no limiting effect on the scope of the invention.

The device 5 comprises two superimposed grids, namely an upper grid 6 and a lower grid 7, which are inclined from top to bottom upstream of the agglomeration strip 3. The inclination of the two grids may be different.

These grids 6 and 7 consist of bars 8 arranged in vertical planes perpendicular to the axis of the roller 2. The cross section of these bars 8 can be arbitrary, for example round, square, rectangular or triangular. In the present example, the bars 8 are equidistant in each of the grids 6, 7 respectively; their spacing e in the upper grid 6 is greater than their spacing e 'in the lower grid 7. For example, e = 8 mm and e' = 4 mm.

In addition, the bars 8 of the upper grid 6 extend, towards the exit thereof, beyond the bars of the lower grid 7 by a length designated by its horizontal projection L.

The operation of this device is easily deduced from FIG. 2, which represents a view of the installation in longitudinal section, that is to say by a vertical plane parallel to the direction of movement of the strip 3.

The mixture consisting of granules of various sizes, contained in the feed hopper 1 flows onto the distribution roller 2, from where it is poured onto the upper grid 6 of the device 5. The large granules, that is to say those whose size is greater than or equal to the spacing e, are retained by the upper grid 6 and flow along it; they then fall on the strip 3 where they form a lower layer a.

The other granules cross the upper grid 6 through the slots of width e between the bars 8 and fall on the lower grid 7. In the same way, the medium-sized granules, that is to say between the spacings e and e ', are retained by the lower grid 7 and flow along it; they then fall on the large layer a: granules, where they form an intermediate layer b.

Finally, the fine granules, that is to say those whose size is less than the spacing e ', pass through the lower grid 7 and fall directly on the layer b of medium particles, to form a layer there. superior c.

The extra length L determines the distance between the start of the formation of layers a and b. It is preferably between 0.1 m and 0.7 m, to ensure sufficient separation of the deposition areas for the granules of different sizes while avoiding excessively reducing the useful length of the strip 3.

Furthermore, the device 5 can be provided with means, known per se and not shown, for varying the inclination of the grids 6 and 7 relative to a horizontal plane. Such a variation in inclination makes it possible to influence the efficiency of the separation of the granules. To further increase the efficiency of this separation and prevent clogging of the grids, they can be subjected to shaking or vibration, preferably continuously.

Fig. 3 shows, also in a perspective view, a second variant of the device of the invention, in which the deflection elements are movable.

This device includes the same conventional loading installation as in FIG. 1. The device 5, intended to operate the vertical segregation of the load on the strip, is here constituted by rotating discs of different diameters, mounted on a horizontal shaft 9. The shaft 9 is placed transversely relative to the strip 3 , and the discs are located in longitudinal vertical planes.

The device 5 shown here also makes it possible to achieve segregation in three layers superimposed on the strip. To this end, it comprises discs 10 of large diameter D, alternating with discs 11 of smaller diameter d. Two large discs 10 are spaced apart by a spacing e which is constant; the spacing e ', also constant, between a small disc 11 and a large neighboring disc 10 is, in practice, less than e / 2, due to the thickness of the discs. Indeed, the thickness of the discs 10 and 11 must be as small as possible, but it must however remain compatible with sufficient resistance of the discs to wear and to deformation.

The operation of this device is explained in FIG. 4, which represents a view of the installation in a longitudinal section taken immediately behind a large disc 10.

The mixture contained in the feed hopper 1 flows onto the distribution roller 2, from where it is poured over the upper part of the assembly 5 of the discs 10 and 11, which here rotates counterclockwise. To avoid an undesirable fall of large or medium granules on the strip by the downstream side of the discs 10 and 11, an inlet deflector 12 is provided, not shown in FIG. 3, which penetrates between the large discs 10 up to the periphery of the small discs 11. The serrated profile of the active edge of the inlet deflector 12 is clearly visible in FIG. 5.

Under these conditions, the large granules are retained at the periphery of the large disks 10 and they are driven by the rotation of the disks to a first outlet deflector 13. This deflects the large granules upstream to form on the strip the bottom layer a.

The rest of the granules fall between the large disks 10, where they meet the small disks 11, less spaced apart than the disks 10. At this stage, the medium granules are in turn retained by the teeth of the inlet deflector 12 and driven by the set of rotating discs up to a second outlet deflector 14. This also transfers them upstream of the strip to form on the layer a an intermediate layer b. The profile of the active edge of the outlet deflectors 13 and 14 is visible, in two fragments, in FIG. 5.

Finally, the smallest granules pass through the set of disks 10 and 11 and fall directly on the layer b of medium granules to form an upper layer c.

Fig. 6 shows, in a longitudinal section view, a third variant of the device of the invention, in which the deflection elements are also mobile. This variant is based on the same principle as that of FIGS. 3 and 4. It differs essentially from the fact that each set of discs 10 and 11 is mounted on a separate shaft 9, 9 'and that these various sets, with their respective deflectors 12, 13 and 14, are arranged one above each other. The advantage of this arrangement lies above all in the fact that it makes it possible to easily and more freely modify the size of the deflected granules, by replacing a single set of discs, such as 11, with another set having a different spacing.

Finally, FIG. 7 shows a group of outlet deflectors usable for example with a device of FIGS. 1 and 2 to operate a combined segregation, that is to say vertical and transverse, of the load. These deflectors can be distinct from the aforementioned deflection means, such as the plates 13 and 14 of FIGS. 4 and 6.

Here, three superimposed deflectors 15, 16 and 17 are shown inclined upstream of the strip, which respectively receive the flows of large, medium and fine granules coming from the device of FIGS. 1 and 2. They have lateral guides which make it possible to channel the various fractions of the load towards predetermined zones of the width of the strip.

At least one of these deflectors, for example the upper deflector 15, could be combined with the corresponding grid of FIG. 1, namely the upper grid 6, by equipping the latter with appropriate lateral guides.

The upper deflector 15 comprises lateral guides 18, oriented in the longitudinal direction relative to the strip. These guides extend over an upper part of the length of the deflector 15; they are extended in the lower part by oblique guides 19, which lead to a central opening and thus concentrate the large granules of the filler in the central zone of the strip.

The intermediate deflector 16 is, in principle, similar to the upper deflector 15; however, it has a wider central opening, thanks to which the average granules of the filler are deposited on a wider central zone of the strip.

Finally, the lower deflector 17 comprises lateral guides 18 which extend over its entire length; these are completed by central guides 20, placed in a chevron and deflecting the fine granules of the filler towards the edges of the strip.

Such central guides 20, placed in a chevron, can also be installed in the intermediate deflector 16, as shown in broken lines in FIG. 7.

In addition, the length of these deflectors 15, 16 and 17 decreases from the upper deflector 15 to the lower deflector 17; in this way, the outlet openings are offset longitudinally above the strip and the different layers of granules are deposited separately.

Finally, the oblique guides 19 and / or the central guides 20 can be articulated at 21 to allow the width of the outlet openings of the respective deflectors to be varied.

The present invention is not limited to the embodiments which have just been described and illustrated. It also extends to the variants that a person skilled in the art could make, for example by inserting a device which makes it possible to cross the flows of materials before the deflectors 15, 16, and 17.

Claims (15)

1. Device for distributing the granular materials loaded on an agglomeration strip of ores, which comprises a feed hopper (1) situated above the initial part of the strip (3), a distribution roller (2) of the load placed under said hopper and extending transversely over the width of the strip as well as a blade (4) for equalizing the layer of materials, characterized in that it comprises, between said distribution roller (2 ) and the upper surface of the strip (3), at least a plurality of parallel deflection elements (8; 10,11), oriented perpendicular to the axis of said distribution roller and distributed over the width of the strip, that the distance (e; e ') between two neighboring deflection elements belonging to the same plurality of elements is chosen so as to allow the passage of the granules whose size is less than or equal to a predetermined dimension and to deviate the granules whose Tai It is greater than said predetermined dimension, and in that said deflection elements are, at least in part, inclined downward in the direction opposite to the direction of movement of said strip. 2. Device according to claim I, characterized in that the distance between two neighboring elements is constant within the same plurality of deflection elements. 3. Device according to either of claims 1 and 2, characterized in that said deflection elements (8) are fixed. 4. Device according to either of Claims 1 to 3, characterized in that the said deflection elements belonging to the same plurality consist of bars (8) which are arranged in a sheet and which thus form a grid ( 6,7) inclined upstream of the agglomeration strip. 5. Device according to either of Claims 1 to 3, characterized in that the said deflection elements consist of plates, the upper part of which is cut obliquely and is thus inclined upstream of the strip d 'agglomeration. 6. Device according to either of claims 1 and 2, characterized in that said deflection elements (10,11) are movable. 7. Device according to claim 6, characterized in that said movable deflection elements are bodies of revolution which rotate about an axis parallel to the axis of said distribution roller (2). 8. Device according to claim 7, characterized in that said movable deflection elements consist of discs (10,11) mounted on at least one shaft (9,9 ') parallel to the axis of said distribution roller (2 ). 9. Device according to either of claims 1 to 8, characterized in that it comprises deflection means (12; 13, 14), adapted to said elements for deflecting the granules. 10. Device according to claim 9, characterized in that said deflection means are constituted by plates (13, 14), arranged at the outlet of the deflection elements (8; 10,11) and upstream thereof. ci with respect to the direction of movement of the agglomeration strip (3), in that these plates (13,14) are inclined and in that they extend on the one hand to immediate proximity of the elements of deflection to which they are respectively adapted, and secondly to the region of the strip to receive the granules from the corresponding deflection elements. 11. Device according to claim 10, characterized in that at least one of said plates (13,14) has notches at least along the edge to be inserted between said deflection elements (8; 10,11). 12. Device according to either of claims 1 to 11, characterized in that it includes deflectors (15, 16, 17) provided with lateral guides, respectively central (18, 19, 20), for directing the granules respectively towards one or more zones of the width of the strip. 13. Device according to claim 12, characterized in that at least a portion of said lateral guides, respectively central (18, 19; 20) are articulated (21) relative to said deflectors. 14. Device according to either of claims 1 to 13, characterized in that it comprises at least one additional equalization blade (4 '; 4 ") associated with one of said pluralities of deflection, respectively to one of said deflection means (13,14). 15. Device according to either of claims 1 to 14, characterized in that it comprises means for shaking, respectively for vibrating said deflection elements, individually or in groups.