GB2127147A - Dust removal apparatus and method - Google Patents

Abstract

Apparatus for controlling pollution when handling bulk cargoes of pulverulent material comprises a frame 60 supporting a body 12 which defines an aperture 13 through which the bulk cargo is loaded into a container 66 of a vehicle 65. Air currents are generated by a fan unit drawing air into a duct 64 adjacent the aperture 13, which air currents flow both downwardly through the aperture 13 and horizontally immediately beneath the aperture so as to create an air curtain. Dust entrained in rising air currents, produced as a load is deposited through the aperture in the container 66, are deflected by the air curtain and drawn into the duct 64 leading to a filtration assembly 63, in which the dust is separated from the air flow. Screens (15, 16 & 61) depend from the body 12 around three sides of the aperture 13, to effect a seal to the vehicle container 66, thereby to ensure the air curtain extends across the aperture 13, towards the duct 64. <IMAGE>

Description

SPECIFICATION Dust removal apparatus and methods This invention relates to apparatus and methods for removing dust from a pulverulent material handling site where the material is to be loaded into a container.

The handling of pulverulent materials frequently causes significant dust pollution, and the more finely divided the pulverulent material, the greater is the likelihood of a dust problem. Despite this, when pulverulent materials are being handled on a small scale, it is possible to design totally sealed handling apparatus so that the likelihood of pollution is largely eliminated. On the other hand, when bulk cargoes of a pulverulent material are to be transferred from one container to another, the use of a sealed system maywell be impractical - for example, in the case of the transfer to a motor vehicle of such a bulk cargo from the hold of a ship or from a store.

In such a case, experience has shown that often the only economically-viable way to transfer the material is to employ a crane or like arrangement having an appropriately designed open grab or bucket for removing the cargo from the hold of the ship and depositing that cargo in the vehicle to be loaded.

This is especially so where the vessel to be unloaded is lying in a tidal berth and hence may rise and fall relative to the quayside where a vehicle to be loaded is positioned.

Observations of the unloading of a bulk cargo of pulverulent material from a vessel by means of a crane fitted with an appropriate design of bucket or grab have shown that the major source of dust pollution is the actual despositing of the pulverulent material into an open-topped vehicle body. Typically, the grab or bucket is emptied from a position some height above the vehicle body floor, such that the pulverulent material strikes the bottom of the vehicle - or material already loaded thereinto - with considerable force, and air in the vehicle body displaced by the depositing of material tends to carry upwardly and outwardly from the vehicle body a considerable quantity of the material.Naturally, the more finely divided is the pulverulent material and the lower is the density of that material, the greater is the likelihood of there being atmospheric pollution caused by the pulverulent material rising on air currents and being carried away from the vehicle being loaded.

It is a prime object of this invention to provide apparatus and methods for removing dust from a pulverulent material handling site in such a way that the operation of loading a container for the pulverulent material - such as a vehicle body - may be effected with a much reduced likelihood of atmospheric pollution by the pulverulent material rising from the container.

According to one aspect of this invention, there is provided apparatus for removing dust from a pulverulent material handling site where the material is to be loaded into a container, which apparatus comprises body means defining an aperture through which the pulverulent material to be loaded into a container is to be desposited, flexible seal means arranged to effect at least a partial seal between the body means and an opening of the container to be loaded, air extraction means to extract air from the space between the aperture in the body means and the seal means thereby to create a downward air-draught through the aperture and a separator unit through which the extracted air is passed before being exhausted to the ambient, thereby to separate from that air any pulverulent material dust entrained therein.

The apparatus of this invention is used in conjuction with a bulk loading device such as a crane having a bucket or grab for transferring the pulverulent material to the container to be loaded. The continuous extraction of air from the space between the container to be loaded and aperture in the body means through which the pulverulent material is deposited serves to ensure that any dust rising from the deposited material is carried away to the separator unit rather than rising upwardly through the aperture and hence into the ambient atmosphere.In order for the apparatus to function effectively, it is importantthatthe airflow in the region ofthe aperture and caused by the air extraction means has a volume flow rate sufficiently high to ensure that during the depositing of a mass of pulverulent material through the aperture, there is still an air down-draught through the aperture, notwithstanding the displacement of air by the deposited pulverulent material. Moreover, it is important that the seal means is arranged to provide an adequate seal to ensure that the just-described air flow takes place.

The seal means may substantially seal the whole of the body means to the container to be loaded, around the aperture in the body means, such that substantially all the air extracted by the air extraction means has been drawn downwardly through the aperture. An alternative is to generate an 'air curtain' by means of the air extraction means, which air curtain has a substantial generally horizontal flow rate across the aperture. This may be achieved by arranging the air extraction means to draw air from one side of the aperture in the body means, and for the seal means to effect a substantial seal to the container being loaded around the aperture except on the side of the aperture opposed to the side wherefrom the air extraction means draws air.In this way, in addition to the down-draught through the aperture created by the air extraction means, a cross-draught also will be created, to entrain any rising pulverulent material.

The apparatus of this invention may take two distinct forms; in the first of these, the body means is generally in the shape of a frame defining the aperture, the flexible seal means depending downwardly from the body means whereby the body means is positioned directly over the opening to a container to be loaded, and the pulverulent material is deposited through the aperture directly into the container; and in the second of these forms, the body means may include a hopper disposed beneath the aperture through which the pulverulent material is deposited, a ducted conveyor leading from the hopper to a downwardly-facing discharge opening in the body means, and the flexible seal means being disposed around that discharge opening, for sealing substantially to an opening in the container to be loaded.In this second form of the apparatus of this invention, the air extraction means should serve to remove air from the entire space between the aperture in the body means and the container opening through which the pulverulent material is deposited, the ducted conveyor constituting a part of that space.

In order further to assist the prevention of air rising upwardly through the aperture when the apparatus is in use, notwithstanding the downdraught therethrough, it is greatly preferred for there to be deflector plates mounted around the aperture, which deflector plates slope inwardly and downwardly with respect to the body means defining the aperture. Such deflector plates tend to deflect generally inwardly any rising air currents in the region of the flexible seal means, such that the deflected air is brought downwardly once more by the main body of the down-draught through the aperture. In a preferred embodiment, the body means defines a generally rectangular aperture, with four inwardly directed deflector plates mounted around the periphery thereof.

In addition to the deflector plates, one or more deflector bars may be mounted to extend across the aperture. Preferably, each such bar has an inverted V-shape, and serves the combined purposes of increasing the down-draught through the aperture, for a given volume air flow rate through the fan unit, breaking up the pulverulent material passing through the aperture and deflecting back down any upwardly rising air currents carrying the pulverulent material.

Conveniently there is an opening in the body means adjacent one end thereof and on substantially the same level as the aperture defined by the body means, the opening being connected by a duct to the air extraction means. In order to obtain the required air flow pattern, it is much preferred for there to be a chamber within the body means which chamber is positioned between said air extraction opening and the aperture in the body means.

The seal means may comprise a number of flexible rectangular sheets attached by their upper edges to the body means to hang downwardly therefrom. In a case where the air extraction means only creates a down-draught, for such sheets may be provided, arranged in two pairs in a rectangular formation to surround the aperture, and disposed to effect seals against the container to be loaded. The two seal sheets intended to lie along the front and rearwalls of a container to be loaded are preferably sub-divided into a plurality of blades, each of which overlies to some extent the next adjacent blade.

For the case of loading a relatively long container, as compared to the length of the aperture, one of the seal sheets may be disposed to seal against the material loaded in the container, as the loading proceeds, the container being moved relative to the body means as the container fills. An alternative is to have one of the seal sheets sufficiently long to effect a seal against one end wall of the container throughout the loading operation, the seal sheet overlying loaded material as the container and body means are moved relatively. Yet another possibility is to have one seal sheet mounted on the body means for horizontal movement in a direction perpendicular to the pane of the sheet.Such movement may be controlled by a servo-system sensing the position of the end face of a container being loaded relative to the body means, or the seal sheet may be springloaded always to engage said end face of the container.

For the case where an air-curtain is created across the aperture, most advantageously seal sheets are provided on three sides of the body means, whereby air may be drawn over loaded material through such gap as exists between the body means and the container. If a moving seal sheet or a relatively long seal sheet is provided to seal against one end face of the container, the side of the aperture opposed to that moving or relatively long seal sheet preferably has no seal sheet.

In the second form of this invention, the part of the body means defining the aperture is physically spaced from a second part of body means which defines a dishcarge opening around which seal means is provided. The two parts are connected together for example by means of a screw or belt conveyor which conveyor serves to transfer to the discharge opening material deposited through the aperture into a hopper, the discharge opening being positioned above a container to be loaded with the material. For such an arrangement the extraction means should draw air from the body means such that there is a down-draught created through the aperture, as in the first described form of this invention.This second form of the invention has however the advantage that the aperture in the body means may be disposed at a lower level than the discharge opening, and this may assist the unloading of a bulk cargo for example from the hold of a ship.

In either form of the invention, the separator unit may take any convenient form, having regard to the mass air flow rate effected by the extraction means and the type of a pulverulent material with which the apparatus is to be used. For example, the separator unit may comprise a known form of cartridge filtration unit so designed that the material separated by the unit falls under gravity into a hopper for subsequent disposal. In order to allow optimum utilisation of any of the forms of apparatus of this invention, it is preferred for it to be constructed as a wheeled self-contained unit, allowing the apparatus to be positioned appropriately for example on a quayside so that it may be used when a pulverulent material cargo in bulk form is to be unloaded from the hold of a ship and loaded into a container lorry.

Such a wheeled unit may advantageously be selfpropelled.

According to a second aspect of this invention, there is provided a method of loading a pulverulent material into a container, comprising depositing the material through an aperture defined by body means which is at least partially sealed to a container to be loaded, there being deflector plates within the aperture which plates slope downwardly and inwardly of the aperture to deflect air flows below the aperture, extracting air from the space below the aperture at a rate sufficient to cause a down-draught through the aperture, and passing the extracted air through separator unit to remove therefrom any pulverulent material entrained therein.

The method of this invention may be performed in such a manner as substantially all of the air extracted from said space passes downwardly through the aperture. Alternatively, the sealing may permit the entry of air into said space from a position opposed to the air extraction region, whereby a substantially horizontal air flow in the form of an 'air curtain' is established beneath the aperture.

When performing either method of this invention, it is most important that the air extracted from the space below the aperture is removed at a sufficiently high rate such that there will be no upward air currents through the aperture, notwithstanding the depositing of bulk material through the aperture and hence the displacement of air from within said space. Preferably, therefore, the average rate of flow of air downwardly through or below the aperture lies in the range of from 1.0 to 3.0 mis, which for a typical installation particularly adapted for the handling of bulk materials requires a volume extraction rate in the range of from 3.75 to 5.5 m3/s.

The sealing between the body means and the container is preferably effected by means of a plurality of flexible seal members, attached to the body means so as to depend downwardly therefrom.

The seal members are advantageously arranged in a rectangular formation with two opposed seal members spaced by a distance sufficient to lie over the sides of the container to be loaded. Since most motor vehicle containers are manufactured with a standard width, said two opposed seal members may be spaced by a pre-set distance so that the apparatus may be employed with any standard container. The other two seal members may be spaced apart by any appropriate distance not greater than the length of the container to be loaded, and at least one of the two seal members should have a downward extent sufficient to reach the bottom of the container to be loaded. Where an air curtain is to be established, only three such seal members need be provided.

With the above-described sealing arrangement, the apparatus may be used effectively to load a container irrespective of the length of the container, provided that the length thereof is not smaller than the distance between the rear seal member and the front seal member (when provided). A loading operation may therefore proceed in the following manner. Initially, the container is positioned such that the shorter of said other two seal members lies within but against the front of the container to be loaded, and the larger of said other two seal members lies within the container so as to extend downwardly to touch the floor of the container. The side seal members should lie against the side walls of the container.A substantial seal is thus effected between the seal members and the container itself, and the air extraction means can be operated so as to create the required down-draught of air through the aperture. Loading may then commence until the space within the container and between the front and rear seal members is sufficiently full; thereafter, the container may be moved forwardly with respect to the apparatus till the aperture is overlying a part of the container still to be loaded. In this position, the front (shorter) seal member should seal against material deposited in the container. The movement should not however be so great that the aperture overhangs the rear of the container, nor should the movement be such that the front seal no longer is able to contact already-loaded material within the container.After this movement, loading may continue either until the container is full, or until that section of the container is full, in which latter case the container may be moved once more with respect to the apparatus and loading continued. From the foregoing, it will be appreciated that the loading method of this invention may be performed either in a single step, with a relatively short container, or in two or more steps, depending upon the actual length of the container relative to the spacing between the front and rear seal members.

By way of example only, three specific embodiments of this invention will now be described in detail, reference being made to the accompanying drawings, in which: Figure 1 is a general perspective view of a first embodiment of a dust removal apparatus contructed in accordance with this invention; Figure 2 is a second general perspective view of the apparatus shown in Figure 1; Figure 3 is a general perspective view, partially from above of the part of the apparatus body defining an aperture through which pulverulent material is deposited; Figure 3A is a partially cut away view of the body part shown in Figure 3; Figures 4, 4A and 4B are three views of the body part shown in Figures 3 and 3A, Figure 4 being a plan view, and Figures 4A and 3B being sectional views taken on lines A-A and B-B marked on Figure 4;; Figure 5 is a sketch illustrating how the apparatus of Figures 1 to 4 is employed in conjunction with a motor vehicle to be loaded with pulverulent material; Figure 6 is a diagram illustrating airflow paths during a loading operation; Figure 7shows diagrammatically a first stage of a loading procedure using the apparatus of Figures 1 and 2; Figure 8 is a view similar to that of Figure 7, but showing a second stage of a loading operation; Figure 9 is a general perspective view of a second embodiment of dust removal apparatus constructed in accordance with this invention; and Figure 10 is a partially cut-away general perspective view of yet another embodiment of dust removal apparatus constructed in accordance with this invention.

Referring initiallyto Figures 1 to 8, there are shown the construction and operation of dust removal apparatus specifically intended for use in the bulk handling of pulverulent material, such as finely divided chalk or so-called tapioca granules which latter material nevertheless includes a high proportion of very finely divided tapioca powder. The loading of such materials in bulk generally causes considerable pollution problems because a dust cloud of the material rapidly forms and rises from the site of handling of the material, and the described apparatus of this invention seeks at least largely to eliminate such pollution.

The apparatus comprises a housing 10 which conveniently is in the form of a closed box but having doors appropriately provided to allow access to the interior thereof. For example, the housing 10 may be in the form of a conventional metallic container normally used for the transport of goods.

The housing 10 is provided with four castors 11 to allow movement of the apparatus from one site to another, and provided within the housing 10 is a motor-driven fan unit (not shown) for a purpose to be described below. The fan unit may for example comprise a diesel engine drivingly coupled to a centrifugal fan, there being provided within the housing 10 the required associated equipment for the proper running and control of the engine.

Mounted on the housing 10 so as to extend laterally from one side of the housing is a body 12 which defines an aperture 13 through which material to be loaded into a container is deposited. The body 12 is disposed on the housing 10 at a height appropriate to lie over the highest container to be loaded in conjunction with the apparatus, and thus the lower edge 14 of the body is typically 3m above the ground. Depending downwardly from the lower region of the body 12, around the aperture 13 therein, are seal members 15, 16, 17 and 18. The members 15 and 16 extend in a generally parallel disposition along the long edges of the body 12, and are in the form of relatively stiff but flexible sheets made of a natural or synthetic rubber or plastics material.Seal member 17 has a downward extent substantially equal to that of seal members 15 and 16, but seal member 17 is formed from a plurality of separate strips 17a, 17b ... each of which is flexible and overlaps to some extent the next adjacent strip.

Seal member 18 is similarly constructed to seal member 17, but has a downward extent equal approximately to twice that of seal member 17.

As can be seen from Figures 3, 3A and 4, 4A and 4B as well as Figures 6 to 8, the body 12 is made up of four outer plates 19 to 22, a generally U-shaped top plate 23 and four internal deflector plates 24, 25, 26 and 27. The aperture 13 is thus defined primarily by the deflector plates 24 to 27, each of which is disposed so as to slope both downwardly and inwardly, from the upper edge thereof. The side plate 19 is cut away as shown in Figures 1,2 and 3 to facilitate the depositing of cargo through the aperture 13. Extending across the aperture 13 is a plurality of bars 28, each of inverted V-shape, provided for a purpose to be described below.

End plate 20 of the body 12 is provided with a rectangular opening, to which is connected a duct 29, leading through an end wall of the housing 10 to a plenum chamber (not shown), mounted within the housing 10. The plenum chamber has a hopper at its lower end, whereas the upper part of the plenum chamber communicates with a filtration cabinet 30 mounted on top of the housing 10. Within the cabinet is a plurality of filter elements (not shown) for separating solid particulate material entrained in air flow passing through the cabinet 30 from the plenum chamber. The outlet from the cabinet 30 is connected by a duct 31 to the inlet of the fan unit in the housing 10, the outlet from the fan unit being fed into a discharge pipe 33 venting to atmosphere.A portion of the air discharged by the fan unit is bled off into the housing 10, for cooling of the engine, as well as to provide its combustion air supply.

When the seal members 15,16, 17 and 18 respectively effect seals against a substantially solid body, operation of fan unit will thus cause air to be drawn downwardly through the aperture 13 and into a chamber defined between plates 20, 23 and 25 at one end of the body 12 before entering the duct 29 leading to the plenum chamber in the housing. From there, the air is drawn by the fan unit through the filtration cabinet 30, where the solid matter is filtered out to drop into the hopper below the cabinet, the extracted air after passing through the fan unit being exhausted to atmosphere through pipe 33. The hopper has a valved discharge opening to allow the emptying thereof.

The operation of the above described apparatus will now be explained with reference to Figures 5 to 8. The apparatus is positioned on a quayside, adjacent to a crane or derrick, and a vehicle having a container to be loaded with the bulk pulverulent material cargo, such as the fixed-chassis lorry 35 (Figure 5) having a load-carrying body in the form of an open topped container 36, is parked beneath the body 12 of the apparatus.

Typically, the length of the container 36 may be about twice the distance between the seal members 17 and 18, and the lorry is first positioned beneath the body 12 such that the seal member 17 bears against the front wall 37 of the container 36. When so positioned, the seal member 18 projects down into the container 36 so as to engage the floor thereof. It will be appreciated that the separation of the seals 15 and 16 must be such that they may engage the outer sides of the container 36, but the width of such container lorries is largely standardised and hence the apparatus shown in Figures 1 and 2 may be used with a very large number of different designs of bulk cargo carving lorry.

Loading of the pulverulent material may then commence for example by means of a crane or derrick having a grab or bucket fitted thereto, or by means of an elevator, the loading device serving to deposit the pulverulent material through the aperture 13 into the container 36 to be filled. During this loading operation, the motor-driven fan unit within the housing 10 is operated, such that there is a downward air current through the aperture 13, and between the bars 28, as indicated by arrows 'A' shown in Figures 6 and 7. The bars 28 in effect restrict the area of the aperture 13 and hence for a given volume airflow rate through the aperture, the linear flow rate is increased.Moreover, the bars by virtue of their inverted V-shape, serve to break-up the pulverulent material deposited through the aperture, and also to assist in giving the material deposited in the container a flatter profile.

As the material is deposited through the aperture 13 as illustrated by arrow 'B' in Figure 6, rising air currents are generated within the container 36 (as illustrated by arrows 'C' in Figure 6) primarily because the material deposited displaces air within the container. The inwardly and downwardly sloping deflector plates 24 to 27 as well as the deflector bars 28 serve to deflect these rising air currents, thus at least slowing if not all together stopping the rising air currents together with any pulverulent material entrained therein. As a result, virtually no pulverulent material rises upwardly away from the aperture 13, and pollution by the material is substantially eliminated.

As the volume of material deposited on the floor of the container 36 rises, the seal 18 starts to be deflected as shown in Figure 7, the deposited material being heaped as shown and lying at the so-called angle of repose within the container. The seal effected by seal member 18 is at all times maintained, by virtue of the contact with the deposited material, the seal member being deflected as necessary. Eventually, when the front portion of the container 36 has been largely filled, the lorry 35 is moved forwardly relative to the apparatus, such that the container 36 takes up the relative position shown in Figure 8. Here, the seal member 18 is deflected as necessary to lie over the rear wall of the container, thus still maintaining a seal thereagainst.The shorterfront seal member 17 however now makes contact with and effects a seal against the alreadyloaded material within the container 36. Loading may then continue in the same way as before, until the container is full. Of course, in the case of a particularly long container, more than two loading steps may be employed; and similarly, for the case of a container not substantially shorter than the distance between the seal members 17 and 18, loading may be effected in a single step.

It will be appreciated that the volume flow rate for the air drawn by the fan unit within the housing 10 should be sufficient to ensure that all the air displaced by the depositing of material within the container 36 will be drawn into the duct 28, whilst maintaining the downward air draught through the aperture 13. In the case of the illustrated apparatus, a volume flow rate of about 4.6m3/s is employed, giving a linear airflow rate through the aperture 13, between the bars 28, of 1.25 m/s.

Figure 9 shows a second embodiment of this invention which embodies the same operating principles as have been described above with reference to Figures 1 to 8, and so far as is possible, parts common to the first embodiments, or performing substantially the same function, are given like reference characters and will not be described in detail again here. This second embodiment differs however in that the aperture through which pulverulent material is deposited is spaced from a discharge opening fitted with seal members and inteded for overlying an open-topped container to be loaded.

Thus, the apparatus comprises a motor-driven chassis unit 50 on which are separately mounted the housing 10 and the filtration cabinet 30. Also mounted on the chassis 50 is a body 51 having three distinct interconnected parts, comprising a hopper 52, a conveyor duct 53 and a discharge assembly 54.

The hopper 52 is of generally rectangular crosssectional shape and has provided within the mouth thereto four deflector plates 55, which correspond generally to the deflector plates 24 to 27 of the first-described embodiment. A conveyor mechanism such as a belt or screw conveyor is provided within duct 53, leading from the base of the hopper 52 to the top of the discharge assembly 54. An appropriate motor-drive arrangement for the conveyor is also provided, to allow the transfer of material deposited in the hopper 52 to the top of the discharge assembly. The discharge assembly 54 defines a downwardly-facing discharge opening around which are provided the seal members 15, 16, 17 and 18, corresponding to the similarly numbered seal members of the first described embodiment.

Though not shown in Figure 9, one or more air ducts are provided to allow the extraction of air from the body 51, from one or more points. For example, two such ducts may be provided, one adjacent each end of the conveyor duct 53, to allow air to be withdrawn primarily from the hopper 52 but also from the discharge assembly 54. However, provided that the seals of the discharge unit effect a sufficient seal against a container to be loaded, then only a relatively small amount of air will be withdrawn from this part of the apparatus, corresponding to the leakage of the seals together with the displacement of air caused by the depositing of material in the container.

The above-described second embodiment of this invention is used in much the same manner as the described first embodiment. However, the height of the discharge unit 54 is readily adjustable for example by pivoting the body 51 on the chassis 50.

Moreover, the hopper 52 is at a lower height than the body 12 of the first-described embodiment and consequently the depositing of material thereinto is simpler and often may be effected more readily and rapidly, for example by means of a bucket loader.

Figure 10 shows a third embodiment of this invention, and again so far as is possible, parts common to the first embodiment, or performing substantially the same function, are given like reference characters and will not be described in detail here.

The third embodiment of this invention employs seals on three sides only of the aperture 13 in the body 12, so that an air curtain, comprising a generally horizontal air flow immediately beneath the aperture 13, can be generated in addition to the down-draught through the aperture, as air is extracted from the space below the aperture. In addition, a moving seal is provided, to assist the accommodation of different lengths of vehiclemounted containers to be loaded, and also to permit loading along the length of the containers.

A free-standing frame 60 supports the body 12 at an appropriate height so that a vehicle may be driven therebeneath, the body 12 defining the aper ture 13 through which the pulverulent material is to be deposited into the vehicle container. On both long sides of the body 13 there are provided flexible seal members 15 and 16, depending downwardly so as to effect a substantial seal against a container beneath the body 12. Between the side seal members 13, there is provided an end seal member 61, slidably mounted on rails 62 extending horizontally from the body 12.The slidable seal member is spring urged to the left (in Figure 10) but may be moved to the position shown in outline in that Figure against the spring force for example by a vehicle reversing beneath the body 12, the rear of the vehicle container engaging the end seal member 61 and then moving that member as far as is appropriate. No seal member is provided at the front of the aperture (i.e.

opposed to end seal member 61), so that air may flow into the space beneath the aperture in the region of the front thereof.

Also mounted on the frame 60 is an extraction fan and separator unit 63, corresponding in function substantially to that described above with reference to Figures 1 to 8, but arranged to extract air through an inlet duct 64, positioned adjacent the right hand end (in Figure 10) of the aperture 13.

A vehicle 65 is loaded using the apparatus of Figure 10 by being reversed beneath the body 12 such that the front part of the vehicle container 66 lies beneath the aperture 13. The extraction and separator unit 63 is operated and the air flow paths are then generally as shown in Figure 10. Thus, in addition to the down-draught in the region of the aperture 13, generally horizontal air flows also occur beneath the aperture, serving as a horizontal air curtain which assists the reduction of pulverulent material rising upwardly, following the depositing thereof in the vehicle container, through the aperture.

As loading proceeds, the vehicle 65 is moved forwards as appropriate, the rear seal member 61 maintaining contact with the rear of the vehicle container and so ensuring that an effective air seal is maintained around three sides of that container.

Moreover, because the front, already loaded, portion of the vehicle container is exposed, the operator of the loading arrangement (for example, a grab or bucket loader) may observe the state of filling of the container and so give directions as to when the vehicle should be moved. The air currents maintained by the unit 63 ensure that virtually no air currents rise above the body 12 of the apparatus and so pollution by dust carried by such air currents is reduced to a minimum.

Claims (26)

1. Apparatus for removing dust from a pulverulent material handling site where the material is to be loaded into a container, which apparatus comprises body means defining an aperture through which the pulverulent material to be loaded into a container is to be deposited, flexible seal means arranged to effect at least a partial seal between the body means and an opening of the container to be loaded, air extraction means to extract air from the space between the aperture in the body means and the seal means thereby to create an air-draught in the region of the aperture preventing air rising upwardly therethrough, and a separator unit through which the extracted air is passed before being exhausted to the ambient, thereby to separate from that air any pulverulent material dust entrained therein.

2. Apparatus according to claim 1 wherein the seal means substantially seals the whole of the body means to the container to be loaded, around the aperture in the body means, such that substantially all the air extracted by the air extraction means is drawn downwardly through the apertures

3. Apparatus according to claim 1,wherein the air extraction means draws air from one side of the aperture in the body means, and the seal means effects a substantial seal to the container being loaded around the aperture except on the side of the aperture opposed to the side wherefrom the air extraction means draws air.

4. Apparatus according to any of the preceding claims, wherein there are deflector plates mounted around the aperture, which deflector plates slope inwardly and downwardly with respect to the body means defining the aperture.

5. Apparatus according to claim 4, wherein the body means defines a generally rectangular aperture, with four inwardly directed deflector plates mounted around the periphery thereof.

6. Apparatus according to any of the preceding claims, wherein one or more deflector bars are mounted to extend across the aperture.

7. Apparatus according to claim 6, wherein each said bar has an inverted V-shape.

8. Apparatus according to any of the preceding claims, wherein there is an opening in the body means adjacent one end thereof and on substantially the same level as the aperture defined by the body means, the opening being connected by a duct to the air extraction means.

9. Apparatus according to claim 8, wherein there is a chamber within the body means which chamber is positioned between said air extraction opening and the aperture in the body means.

10. Apparatus according to any of the preceding claims, wherein the seal means comprises a number of flexible rectangular sheets attached by their upper edges to the body means to hang downwardly therefrom.

11. Apparatus according to any of the preceding claims, wherein the body means is generally in the shape of a frame defining the aperture, the flexible seal means depending downwardly from the body means whereby the body means may be positioned directly over the opening to a container to be loaded.

12. Apparatus according to claim 11, wherein four said sheets are provided, arranged in two pairs in a rectangular formation to surround the aperture, and disposed to effect seals against the container to be loaded.

13. Apparatus according to claim 12 wherein the two seal sheets intended to lie along the front and rear walls of a container to be loaded are sub-divided into a plurality of blades, each of which overlies to some extent the next adjacent blade.

14. Apparatus according to claim 12 or claim 13, wherein one of the seal sheets is disposed to seal against the material loaded in the container, as the loading proceeds, the container being moved relative to the body means as the container fills.

15. Apparatus according to claim 12 or claim 13, wherein one of the seal sheets is sufficiently long to effect a seal against one end wall of the container throughout the loading operation, the seal sheet overlying loaded material as the container and body means are moved relatively.

16. Apparatus according to claim 12 or claim 13, wherein one seal sheet is mounted on the body means for horizontal movement in a direction per pendicularto the plane of the sheet.

17. Apparatus according to claim 3 or any claim depending thereon, wherein seal sheets are provided on three sides of the body means, whereby air may be drawn over loaded material through such a gap as exists between the body means and the container.

18. Apparatus according to any of claims 1 to 10, wherein the body means includes a hopper disposed beneath the aperture through which the pulverulent material is deposited and a ducted conveyor leading from the hopper to a downwardly-facing discharge opening, the flexible seal means being disposed around that discharge opening, for sealing substan tiallyto an opening in the container to be loaded.

19. Apparatus according to claim 18,wherein the air extraction means serves to remove air from the entire space between the aperture in the body means and the container opening through which the pulverulent material is deposited, the ducted conveyor consitituting a part of that space.

20. Apparatus according to any of the preceding claims, wherein the apparatus is constructed as a wheeled self-contained unit.

21. Apparatus according to claim 1 and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

22. A method of loading a pulverulent material into a container, comprising depositing the material through an aperture defined by body means which is at least partially sealed to a container to be loaded, there being deflector plates within the aperture which plates slope downwardly and inwardly of the aperture to deflect air flows below the aperture, extracting air from the space below the aperture at a rate sufficient to cause a down-draught through the aperture, and passing the extracted air through separator unit to remove therefrom any pulverulent material entrained therein.

23. A method according to claim 22, in which substantially all of the air extracted from said space passes downwardly through the aperture.

24. A method according to claim 22, in which sealing may permit the entry of air into said space from a position opposed to the air extraction region, whereby a substantially horizontal airflow is estab lished beneath the aperture.

25. A method according to any of claims 22 to 24 in which the average rate of flow of air downwardly through or below the aperture lies in the range of from 1.5 to 3.0 m/s.

26. A method according to claim 22 and substantially as hereinbefore described with reference to the accompanying drawings.