JP5644582B2 - Method for suppressing dust generation during transport of powder - Google Patents

Description

The present invention relates to a method for suppressing dust generation when a granular material (including dust) is conveyed using a conveying device.

In the conveyance system of a granular material, for example, dust generation occurs at a connecting portion of a conveyor (conveyance device), which is not preferable. In particular, in ironworks, raw materials (powder) such as iron ore, coal, sintered ore, and coke are transported in large quantities by conveyors, so the amount of dust (fine powder) that is generated at the transit area, etc. However, the scattered dust is also a useful raw material. Usually, a dust collector is installed at the location where such dust is generated, and the dust is forcibly sucked and collected.
However, such a dust collection facility is equipped with a suction pipe, dust collector, suction blower, exhaust tower, etc. that cover the raw material transport route, and is a large-scale facility. necessary. For this reason, although water spraying is also performed as a simple dust generation suppressing means, the water content of the raw material is increased, which is not preferable in terms of quality and energy.
In such a situation, there is a need to suppress dust generation simply and with as little moisture as possible, and as one means for that, a technique using foam has been studied and used.

For example, Patent Document 1 discloses a method and an apparatus for supplying a minimum amount of foam sufficient to cover a raw material over the entire width of a conveyor, whereby it is possible to suppress dust generation while saving medicine. Has been.
Further, Patent Document 2 discloses a method of shielding a dust generation location with foam in transferring a raw material. Specifically, for the purpose of preventing dust generation of the raw material at the connecting portion of the conveyor, foam is sprayed from above the raw material to the downstream of the chute installed at the connecting portion. Further, for the purpose of preventing dust generation in the hold at the time of loading, foam is projected from above toward the material discharge part from the turning chute, and the material loading layer is shielded with foam.

JP 2000-62939 A JP 48-42969 A

However, the conventional method still has the following problems to be solved.
The method described in Patent Document 1 is based on the premise that the dust generation site is shielded with foam, and a large amount of foam is required. In addition, it is often difficult to reliably supply a large amount of foam on an operating conveyor. Furthermore, it is difficult for the foam to come into contact with the dust inside the layer of the granular material, and dust is generated again at the subsequent connecting portion, so a large amount of foam must be supplied to each of the connecting portions, for example, It was necessary to install a large number of foam supply devices and to disperse a large amount of foam.
The dust generation prevention method of the transfer part of the conveyor described in Patent Document 2 has a foam chute portion disposed above the conveyor chute and covers the raw material with foam, so that a large amount of foam is required as in Patent Document 1. Met. In addition, the dust prevention method in the cargo hold at the time of loading also arranges the foaming device that supplies foam above the raw material discharge part from the swivel chute, projects the foam toward the raw material discharge part, and foams the raw material. As in Patent Document 1, a large amount of foam was necessary.

The present invention has been made in view of such circumstances, and a dust generation suppressing method at the time of conveying a granular material that can efficiently and economically suppress the generation of the granular material without using a large amount of bubbles. The purpose is to provide.

The dust generation suppressing method at the time of conveying the granular material according to the present invention in accordance with the above object is a granular material comprising any one or more of iron ore, coal, sintered ore, and coke using a conveying device. upon conveying the, before you load the powder and granular material to the conveying device, inclined downward toward the conveyance direction of the powder or granular material, moreover, downward with respect to the horizontal direction, of the powder or granular material Along the slope inclined beyond the angle of repose within the range of 85 degrees or less, the powder particles are slid down toward the falling powder particles on the lower layer side when loaded on the transfer device. Supply foam.

In dust suppression method when powder particles conveyed according to the present invention, the transport device provided with a plurality, in the transit portion of the transport device adjacent to the conveying direction of the powder or granular material, placing the chute with the slope It has Rukoto is preferable.

In dust suppression method when powder particles conveyed according to the present invention, the upstream side of the conveying device, wherein the beveled surface arranged storage hopper example Bei Zheng Rukoto are preferred.

The dust generation suppressing method at the time of conveying a granular material according to the present invention, when conveying a granular material using a conveying device, before the granular material is loaded on the conveying device, the granular material along an inclined slope Since the body is slid down and the foam is supplied toward the falling granular material on the lower layer side when loaded on the transport device, at least the lower layer side of the granular material layer can be brought into contact with the foam. For example, the granular material rolls in the conveying process to cause particle size segregation, so that there are a relatively large amount of coarse particles on the upper surface side of the granular material layer and a large amount of fine powder as a dust generation source on the lower layer side.
Therefore, as described above, since at least the lower layer side of the granular material layer is brought into contact with the foam, a large amount of fine powder can be brought into contact with the foam, so that a large amount of foam is used efficiently and economically. It becomes possible to suppress dust generation of the powder.

Further, a chute having a slope inclined in the range of 85 degrees or less exceeding the angle of repose of the granular material is disposed on the connecting portion of the adjacent conveying device downwardly with respect to the horizontal direction. In the case of sliding down along the slope, particle size segregation can be further generated in the powder particles sliding down the chute. Thereby, the fine powder on the lower layer side of the granular material layer can be further increased, and as a result, the fine powder can be brought into contact with the foam, so that the effect of the present invention becomes more remarkable.

And it is equipped with the slope which inclines below toward the conveyance direction of a granular material in the upstream of a conveying apparatus, and also exceeds the angle of repose of a granular material to the downward direction with respect to a horizontal direction, and the inclination angle of a granular material is 85. When the storage hopper set within a range of less than or equal to the degree is disposed and the powder particles are slid along the slope of the storage hopper, particle size segregation can be further caused in the powder particles sliding down the storage hopper. Thereby, the fine powder on the lower layer side of the granular material layer can be further increased, and as a result, the fine powder can be brought into contact with the foam, so that the effect of the present invention becomes more remarkable.

It is explanatory drawing of the dust generation suppression method at the time of the granular material conveyance which concerns on one embodiment of this invention. It is explanatory drawing of the dust generation suppression method at the time of the granular material conveyance which concerns on a prior art example.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
With reference to FIG. 1, a granular material conveyance facility (hereinafter, also simply referred to as a conveyance facility) 10 that uses the method for suppressing dust generation during granular particle conveyance according to an embodiment of the present invention will be described.
The transport facility 10 has a storage hopper 12 for the granular material 11 and a plurality of (here, two) belt conveyors (an example of a transport device) that transports the granular material 11 cut out from the storage hopper 12 in the horizontal direction. 13 and 14, and a chute 15 disposed at the connecting portion of the belt conveyors 13 and 14 adjacent to each other in the conveying direction of the granular material 11.

The granular material 11 is a raw material (iron ore, coal, sintered ore, coke, etc.) used in an ironworks, but is not particularly limited as long as dust is generated. Ceramic powder, resin powder, food (raw material) powder, or the like may be used.
Moreover, although the belt conveyors 13 and 14 were used for conveyance of the granular material 11, it is not limited to this, The kind and conveyance path | route (for example, horizontal, diagonal, vertical) of the granular material to convey Depending on the case, for example, a conveyor such as a bucket conveyor, a slat conveyor, a steel conveyor, or a screw conveyor can be used. In addition, the number of installed transport apparatuses may be one, or may be three or more, depending on the transport path.

The transport facility 10 is provided with a foam production device 16.
A plurality of (here, two) hoses 17 and 18 are connected to the foam production device 16, and the foam produced by the foam production device 16 is discharged to the downstream ends of the hoses 17 and 18, respectively. Nozzles (foam discharge means) 19 and 20 for (spraying) are attached.
As the foam production apparatus 16, a conventionally known apparatus (for example, an apparatus described in Patent Documents 1 and 2) that produces foam (foam) by mixing a surfactant (medicine) and air with water can be used. In addition, although one foam manufacturing apparatus 16 was used here, you may install multiple units | sets according to the structure of a conveyance installation.

Of the two nozzles 19 and 20 described above, the upstream nozzle 19 is a belt at the upstream end of the upstream belt conveyor 13 (upstream from the supply position of the powder 11 from the storage hopper 12). 23 is installed above (directly above). Further, the downstream nozzle 20 is installed above (directly above) the belt 24 at the upstream end of the downstream belt conveyor 14 (upstream from the sliding position of the granular material 11 from the chute 15).
The bubble discharge ports (spout ports) 21 and 22 of the nozzles 19 and 20 are all directed to the falling powder body 11 which is the lower layer side when loaded on the belts 23 and 24.

The discharge ports 21 and 22 of the nozzles 19 and 20 may be directed to the loading surfaces (also referred to as mounting surface, upper surface, or surface) 25 and 26 of the belts 23 and 24 on which the powder particles 11 are loaded.
Moreover, although the two nozzles 19 and 20 which discharge | release foam are used, 3 or more can also be used according to the generation range and the number of generation | occurrence | production locations of dust (the number of hoses is also the same).
Further, the configuration of the nozzle for discharging bubbles is not limited to the above-described configuration. For example, the nozzle is provided with discharge ports formed at the same or different pitch in the longitudinal direction, and this is used for conveying the granular material. It can also be arranged in a direction perpendicular to the direction (belt moving direction).

Subsequently, a dust generation suppressing method at the time of conveying a granular material according to an embodiment of the present invention will be described with reference to the above-described granular material conveying facility 10.
As shown in FIG. 1, the dust generation suppressing method at the time of conveying the granular material is such that the granular material 11 is loaded on each of the belt conveyors 13 and 14 when the granular material 11 is conveyed using the respective belt conveyors 13 and 14. This is a method of supplying bubbles onto the loading surfaces 25 and 26 of the belts 23 and 24 of the belt conveyors 13 and 14 before being carried out. Specifically, bubbles are continuously supplied from the storage hopper 12 onto the loading surface 25 of the belt 23 before the granular material 11 is cut out (dropped) to the upstream belt conveyor 13 by the nozzle 19. Further, bubbles are continuously supplied from the upstream belt conveyor 13 through the chute 15 onto the loading surface 26 of the belt 24 before the granular material 11 drops onto the downstream belt conveyor 14 by the nozzle 20. .

Therefore, with the movement of the belt 23 of the belt conveyor 13, the foam supplied on the belt 23 moves to the lower side of the storage hopper 12 and comes into contact with the lower side of the falling granular material 11. In addition, as the belt 24 of the belt conveyor 14 moves, the foam supplied on the belt 24 moves to the lower side of the chute 15 and comes into contact with the powder body 11 that is falling.
At this time, the foam supplied on the belts 23 and 24 is in contact with the falling powder 11 from its side (the direction of the lower layer when loaded on the loading surfaces 25 and 26). doing. It is to be noted that the bubbles are discharged (sprayed) so as to come into contact with only the side of the above-described falling powder 11, and the powder 11 and the foam are dropped, and the powder on each belt 23, 24. It is also possible to supply foam on the loading surfaces 25, 26 before the body 11 is loaded.

The following is a description of how the present inventors diligently studied and led to the above-described invention.
2, the two nozzles 19 and 20 attached to the foam production device 16 via the hoses 17 and 18 emit bubbles to the upper surface of the powder 11. I can do it. Specifically, the upstream nozzle 19 blows bubbles from above on the powder 11 cut out from the storage hopper 12a, and blows bubbles onto the powder 11 in the middle of dropping from the storage hopper 12a. Then, in the process in which the granular material 11 falls and rotates, the aim is to mix the foam into the granular material 11. Further, the nozzle 20 on the downstream side supplies bubbles from above the particles 11 just before the particles 11 transfer from the belt conveyor 13 to the belt conveyor 14, and the bubbles are converted into particles in the rolling process of the transfer. 11 is intended to be mixed.

As described above, in the conventional transport facility, by supplying a large amount of foam to each connecting portion of the belt conveyors 13 and 14, dust generation is suppressed by covering the entire granular material 11 with the foam.
However, with this transfer facility, a sufficient dust generation suppression effect could not be obtained. The cause is considered to be that the mixing effect of the foam and the granular material is small, and the foam is not sufficiently brought into contact with the fine powder which is a dust generation source.
As a result of detailed observation of the state of the powder and foam, the present inventors have found that the upper surface side of the powder layer has a relatively large amount of coarse particles, and the lower layer side has a large amount of fine powder as a dust generation source. . This is because particle size segregation occurs in the course of rolling of the granular material, and the coarse particles gather upward and the fine powder gathers downward.

In view of the above-described effects, the present inventors have also proposed a method for further increasing and utilizing the segregation effect of the granular material, that is, the fine particle layer easily gathers on the lower layer side of the granular material layer. The present inventors have conceived the above-described method for suppressing dust generation during the transportation of the granular material according to the present invention, in which bubbles are supplied aiming at the lower layer.
Thereby, it becomes possible to suppress dust generation efficiently and economically, without using a lot of foam which covers the whole granular material.
Note that, as described above, in the granular material, in the rolling process, since the fine powder easily collects on the lower layer side of the granular material layer, the storage hopper 12 and the chute 15 are preferably configured as follows.

As shown in FIG. 1, the storage hopper 12 disposed on the upstream side of the belt conveyor 13 has a slope 27 that slopes downward in the conveying direction of the powder particles 11 and a vertical that faces (opposites) the slope 27. It has a surface 28 (a surface perpendicular to the horizontal direction) and has an asymmetric shape when viewed from the side. The inner width of the storage hopper 12 is reduced toward the lower side (the diameter is reduced), and the shape in plan view may be a rectangle, a square, a circle, an ellipse, or an oval.
As described above, the shape of the storage hopper 12 is defined, and the powder 11 stored in the storage hopper 12 is slid along the slope 27, so that the fine powder is easily collected on the slope 27 side.

Thereby, after cutting out the granular material 11 from the storage hopper 12, fine powder can be further concentrated on the lower layer side of the granular material 11 layer on the belt 23 of the belt conveyor 13. Therefore, immediately before the granular material 11 is cut out on the belt 23 of the belt conveyor 13, the foam 19 is supplied onto the stacking surface 25 of the belt 23 with the nozzle 19, thereby reducing the dust generation effect of the granular material 11 due to the foam. Can be bigger.
Here, the inclination angle θ1 of the inclined surface 27 of the storage hopper 12 is preferably set in the range of 85 degrees or less exceeding the angle of repose of the granular material 11 downward in the horizontal direction.

Thereby, although the granular material 11 can slide down stably along the slope 27 of the storage hopper 12, it is preferable to make a minimum into "the angle of repose of granular material +5 degree | times", and an upper limit is 80 degree | times, Further, it is preferably set to 75 degrees.
In addition, although the angle of repose of a granular material changes with kinds of granular material, if it is a raw material used in an ironworks, it is about 30 to 60 degree | times.
Further, the vertical surface of the storage hopper (the surface facing the inclined surface 27) is not a vertical surface, so that the inner width of the storage hopper narrows from the upper end to the lower end of the storage hopper (for example, the storage hopper 12a) or may be tilted to be identical.

Furthermore, the chute 15 also includes a slope 29 for the powder body 11 to slide down.
Here, immediately before the granular material 11 is loaded on the belt 24 of the belt conveyor 14 from the chute 15, bubbles are supplied by the nozzles 20 onto the loading surface 26 of the belt 24. This is because particle size segregation occurs when the granular material 11 slides down the chute 15 and the fine powder moves to the lower layer, so that the fine powder further concentrates on the lower layer side on the belt 24 of the belt conveyor 14 after the transfer, This is because the contact probability of bubbles and fine powder can be increased.
The inclination angle θ2 of the slope 29 of the chute 15 is also preferably in the above-described angle range of the inclination angle θ1 like the slope 27 of the storage hopper 12.
As described above, it is preferable to set the inclinations θ1 and θ2 of the slopes of the storage hopper and the chute, but the inclination is not limited to this inclination as long as the particles can slide down.

Next, examples carried out for confirming the effects of the present invention will be described.
Here, dry granule of ore is used as a granular material, and this granular material is conveyed by the granular material conveying equipment shown in FIGS. 1 and 2 to measure the amount of dust generation. The dust generation situation was compared. In addition, when using the conveyance equipment of FIG. 2, not only the foam production apparatus but also the case where a water supply apparatus was installed instead of the foam production apparatus, the amount of dust generation was measured.

First, the results of comparing the effects of forced dust collection, the amount of water and bubbles applied, and the method of applying bubbles on the dust generation situation will be described. In addition, the comparison of dust generation situation is the case of normal forced dust collection (using a dust collector) as reference example 1, and the case of not collecting dust (no dust collector, no water or foam spraying) is a reference example Example 2 is a case where dust collection is stopped and water or foam is sprayed using the transport facility of FIG. 2 as Comparative Examples 1 to 10, and only foam is sprayed using the transport facility of FIG. Performed as ~ 3.
Table 1 shows the test conditions and test results.

The amount of application in Table 1 is shown as converted from the water supply amount and the ore transport amount to the amount of water increase of the ore (= (water content) / {(water content) + (ore)} × 100). In addition, the foam was mixed with a surfactant (active ingredient) equivalent to 0.3% by mass with respect to water and foamed while mixing 20 times the volume of air in the foam production apparatus. Using. For this reason, the amount of foam sprayed is obtained by including the amount of surfactant in the moisture of the above-described calculation formula.
In addition, the amount of dust generation was determined as a value per unit time and unit area by placing a plurality of containers around the dust generation location, weighing the dust that has fallen into the containers and accumulated.

Reference Example 1 shown in Table 1 shows the results when normal forced dust collection was performed, and the dust generation amount was 5 g / m ² / hour. On the other hand, Reference Example 2 is a state in which forced dust collection is stopped, and dust is scattered, resulting in a dust generation amount of 100 g / m ² / hour.
On the other hand, Comparative Examples 1 to 5 are results of carrying out water spraying with the transport facility shown in FIG. 2 and increasing the amount of water sprayed from 0.2 mass% to a maximum of 4 mass%. is there. As can be seen from Table 1, the amount of dust generation decreased as the amount of water sprayed increased, but even when the amount of spraying was equivalent to the maximum of 4% by mass (15 g / m ² / hour), Dust suppression effect was not reached.
In Comparative Examples 6 to 10, foam spraying was carried out with the transport facility shown in FIG. 2, and the amount of foam sprayed at that time (the amount of foam corresponding to the amount of water) was equivalent to 0.2 mass% to a maximum of 4 mass. It is the result of increasing to% equivalent. As is clear from Table 1, the amount of dust generation decreased with an increase in the amount of foam sprayed, and the dust generation suppression effect was greater than in the case of water alone. Therefore, although it is thought that the mixing property with the granular material was improved by the foam, since the foam was sprayed from above the granular material, even if the foam was sprayed up to a maximum of 4% by mass, the dust generation suppressing effect ( 10 g / m ² / hour) did not reach when the dust collector was used (Reference Example 1).

On the other hand, Examples 1-3 are the results of increasing the amount of foam dispersion from 0.2% by mass to 1% by mass using the transport facility shown in FIG. Since the angle of repose of the granular material was 45 degrees, the angle of inclination of the cone (slope) at the bottom of the storage hopper was set to 65 degrees downward with respect to the horizontal direction, and the chute installed at the connecting part of the belt conveyor The inclination angle was set to 50 degrees downward with respect to the horizontal direction.
As shown in Example 1 of Table 1, before the granular material was placed on the belt conveyor, since the foam was spread on the loading surface, even when the amount of foam spread is as small as 0.2% by mass, Compared with Comparative Examples 1 and 6 using the transport facility of FIG. 2, the amount of dust generation was significantly suppressed (40 g / m ² / hour). In particular, it was found that by setting the amount of foam sprayed to 0.5% by mass or more, a dust generation suppressing effect equal to or higher than that of Reference Example 1 using a dust collector can be obtained.
From the above, it is possible to efficiently and economically suppress dust generation without using a large amount of bubbles by using the dust generation suppressing method of the present invention at the time of conveying the granular material. I was able to confirm that.

Subsequently, with respect to the above-described second embodiment, the result of comparing the inclination angle of the cone at the lower part of the storage hopper and the effect of the presence or absence of the chute disposed on the connecting portion of the adjacent belt conveyor will be described with reference to Table 2. . In Table 2, when a chute is used, the inclination angle of the slope is set to 50 degrees.

Reference Example 3 shown in Table 2 is the result of disposing the cone at the lower part of the storage hopper of Example 2 perpendicularly to the horizontal direction and removing the chute from the connecting portion of the belt conveyor. Thereby, although the dust generation amount increased to 50 g / m ² / hour, the dust generation amount could be reduced by 10 g / m ² / hour as compared with Comparative Example 7 in which the amount of foam sprayed was the same.
Reference Example 4 is a result of installing a chute at the connecting portion of the belt conveyor in Reference Example 3 , and as a result, the dust generation amount was reduced to 15 g / m ² / hour. Similarly, Example 4 is the result of setting the inclination angle of the cone at the lower part of the storage hopper to 65 degrees in Reference Example 3 , and as a result, the dust generation amount could be reduced to 15 g / m ² / hour.
In Example 5, Reference Example 4, is a result of setting the angle of inclination of the member hopper bottom of the cone to 85 degrees, compared to the results of the cone of Reference Example 4 arranged vertically, amount of dust Can be reduced to 10 g / m ² / hour.
From the above, even if the chute is not arranged at the connecting part of the conveying device adjacent in the conveying direction of the granular material (for example, it is not installed according to the standard of the amount of dust generation or the connecting height), It was confirmed that it was possible to efficiently and economically suppress dust particles without using a large amount of bubbles.

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, a case where a part or all of the above-described embodiments and modification examples are combined to constitute the dust generation suppressing method during conveyance of the granular material of the present invention is also included in the scope of the present invention.
In the above-described embodiment, the case where the present invention is applied to the portion for cutting the granular material from the storage hopper to the belt conveyor and the connecting portion of the adjacent belt conveyor has been described, but the invention is applied to only one of them. You can also

DESCRIPTION OF SYMBOLS 10: Granular material conveyance equipment, 11: Granules, 12, 12a: Storage hopper, 13, 14: Belt conveyor (conveyance device), 15: Chute, 16: Foam production device, 17, 18: Hose, 19 , 20: nozzle, 21, 22: discharge port, 23, 24: belt, 25, 26: loading surface, 27: slope, 28: vertical surface, 29: slope

Claims (3)

Using the transfer device, iron ore, coal, sintered ore, and, upon conveying the granular material consisting of either one or more of coke, before you load the powder and granular material to the conveying device, The powder is slanted downward in the conveying direction of the granular material, and further down along the slope inclined in the range of 85 degrees or less exceeding the angle of repose of the granular material downward with respect to the horizontal direction. A method for suppressing dust generation during transportation of a granular material, wherein the particulate material is slid down and bubbles are supplied toward the falling granular material on the lower layer side when the granular material is loaded on the transportation device . 2. The dust generation suppressing method according to claim 1, wherein a plurality of the conveying devices are provided, and a chute including the inclined surface is disposed at a connecting portion of the conveying device adjacent to the conveying direction of the granular material. dust suppression method when granular material transport, characterized that you have to. In dust suppression method during claim 1 granular material transport of, wherein the upstream side of the conveying device, generation of dust during powder particles conveyed, characterized in Tei Rukoto arranged storage hopper example Bei the slope Suppression method.

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