Abstract:
A storage apparatus suitable for storing granular material in a large tank-like storage container into which material is introduced from an material inlet at a top of the storage container to pile up in a normal manner. A height adjustable leveling apparatus in the form of a rotary scraper is supported within the storage container which engages the uppermost portion of the heaped material and spreads it for leveling the upper surface of the material. Whereby the storage container may be filled to an upper level surface maximizing the useful volume of the storage container. Discharge from a central or peripheral port is likewise maximized by ensuring all material in the container to the discharge level is fed for reclamation.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This is a continuation-in-part application taking priority from PCT patent application serial number PCT/AU99/00747 filed on Sep. 9, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to bulk handling apparatus and in particular to storage apparatus for storing bulk granular materials. 
     2. Discussion of the Prior Art 
     Bulk granular materials are typically stored in silos or large sheds. Silos are mostly utilized for storing grain and reclaiming is achieved through a base cone arranged coincident with the repose angle of the grain such that all material will feed gravitationally to a central outlet for discharge from the silo. A disadvantage of this arrangement is that such silos are relatively high and this necessitates additional cost and complexity for equipment to feed grain into the silos. 
     Mined bulk granular material is often stored in sheds where it may be deposited, for example, by a central conveyor supported in the apex of a conventional portal frame shed. Reclaiming of the product is achieved using front end loaders charging dump hoppers travelling over an out-load conveyor which may be arranged in a tunnel and fed from a central point. Capital costs of such designs are very high and large land areas are required for such storage. Additionally, there is an ongoing reclaim cost necessitated by the use of supervised machinery to reclaim the material from the shed. 
     A further disadvantage of these systems is that many bulk solids have properties that will allow the forming of rat-holing and make those materials bridge over an out-loading point thereby stopping the exit flow of materials. The problem of bridging and rat-holing may become extreme in cases where material has been in static storage for a considerable period of time thereby having allowed gravitational pressures to cause settlement or compaction of what may have been a relatively freeflowing material. 
     Hydroscopic properties of some materials will allow them to become sticky in storage adding further to the problems of extracting such materials from silo type storage. Mined bulk granular material is also stored as open stockpiles serviced by rail mounted stacker reclaiming machinery. Disadvantages of such systems include the high cost of stockpiling and management with regard to the environment and high maintenance costs of the necessary equipment for stockpiling and reclaiming. 
     The present invention aims to alleviate at least one of the above disadvantages and to provide storage apparatus which will be reliable and efficient in use. 
     SUMMARY OF THE INVENTION 
     With the foregoing and other objects in view, this invention in one aspect resides broadly in storage apparatus suitable for storing granular material. The storage apparatus includes a storage container, a material inlet at the top of the storage container, a material outlet at the base of the storage container, and a height adjustable leveling apparatus for leveling the upper surface of material contained in the storage container. Thus the upper surface may be levelled to enable the container to be filled to capacity when filling, and when discharging to level the upper surface to ensure complete discharge of all materials as the container is emptied from the base. 
     The leveling apparatus could be any suitable form of conveying apparatus which conveys the material being fed into the container towards the outside of the container when filling and when emptying which conveys the material remaining about the periphery of the container towards the center of gravitational; discharge at the base. 
     In a preferred embodiment, the leveling apparatus is in the form of a driven rotary scraper rotatable about a vertical axis and having an overall diameter substantially equal to the inside diameter of the container, the scraper having blades thereon engagable with the upper surface of material in the container so as to move the engaged material selectively inward or outward as required. For this purpose, the blades may be fixed or adjustable and the wheel may be reversible to control the direction of feed of the granular material. 
     Alternatively, the vanes may be reversible or the scraper may include alternate sets which may be lowered for engagement with the granular material. Preferably the rotary scraper includes an outer ring frame supported on vertically adjustable mountings on or adjacent the container wall. It is also preferred that for the best mechanical advantage, the drive apparatus for selectively rotating the wheel are mounted on the vertically adjustable mountings and drive the outer ring frame. The drive motor may drive a pinion engaged with an annular rack on the ring frame. Alternatively, the rotary scraper may be supported from a central column and drive therefrom. However this would impose complexities and high loads due to the need to transmit high operating torque through the column to an inner ring of the rotary scraper. 
     This invention may also be applied to reclaiming materials from an unsupported pile. Thus according to another aspect this invention resides broadly in a method of and apparatus for reclaiming material from a stockpile of granular material including: providing a height adjustable spreading apparatus for spreading material from the upper surface of the stockpile outwardly for passage to the base of the stockpile; providing reclaiming apparatus at the base of the stockpile, and operating the spreading apparatus to cause feeding of that material in the stockpile which does not initially flow gravitationally to the reclaiming apparatus toward the base of the remaining stockpile to enable feeding of substantially all the material in the stockpile reclaiming apparatus. The stockpile may be supported on a base pad containing the reclaiming apparatus and, if desired, the stockpile may be contained within a peripheral wall. In a further aspect this invention may utilize open stockpile arrangements suitable for storing and or blending granular bulk solids and including: a circular storage or blending area; material outlet port or ports positioned on the storage area centerline at the base of the storage area; peripherally positioned supporting towers providing support for the height adjustable leveling-reclaiming apparatus; a centrally positioned support column and distribution means and the leveling apparatus generally as described earlier, may be supported in a peripheral annular support truss, this support truss in turn may be supported via the provision of a series of cabled sheaves and counterweights arrangements at the peripheral support towers. 
     The counterweight and cable and sheave system will be arranged to create a balance of mass between the leveling apparatus and the counterweights. Such a design requires only limited force to promote the up or down movement of the leveling/reclaiming apparatus The design of the counterweight sheave system will ensure that limited travel of the counterweights will enable the leveling apparatus to traverse the full operational height of the stockpile. 
     The leveling apparatus may then be directed up or down by simple mechanical means positioned at the base of each of the support towers. When applying the foregoing to a very large diameter stockpile additional support for the leveling apparatus may be provided at the inner hub of the leveling apparatus. 
     An inner annular truss providing support to the leveling apparatus may be counter balanced by a cable sheave and counterweight arrangement housed inside the hollow center support column. A single mechanical raising and lowering arrangement such as for instance a hydraulic ram may be selected to effect the required up and down travel of the leveling apparatus. 
     The leveling apparatus in the open stockpile application suitably has the scraper blades positioned in such a way so as to have the blades on the underside of the inner section of the leveling apparatus scrape the material outward to a position coincident with the top of the repose angle of the material stored. The rest of the scraper blades on the outer section of the leveling apparatus are positioned opposite to provide the outer part of the apparatus with inward scraping blades. These scraper blade positions ensure that the stockpile can be totally reclaimed of all stockpiled material. It follows that the reclaim ports should be positioned under the stockpile coincident with a position vertically down from the top of the repose angle at the top of the stockpile. 
     Driving of the leveling apparatus in the open application may be by means of a friction drive as described earlier but with the motor/gearbox or hydraulic drive pack drive units positioned at three equi-spaced points at the periphery on the leveling-reclaiming apparatus and having electric power supplied via a slipring arrangement at the center hub. Actual friction drive power is suitably applied at the outer annular support truss, this support truss is slideably attached to the perimeter support towers and supported by a series of counterweights inside the support tower structures. The support towers serve as the reaction columns for the drivers. 
     Operation of the leveling apparatus may be determined so as to have the apparatus, while the stockpile is in charging mode, rotating at its top position this will allow the incoming material to form a pile around the center column. This pile is embraced by the angle of repose of the material stored. 
     With only the material at the top of the pile being bladed outward, different grades of material may be added to the stockpile thus forming within the parameters of the installation an ever widening frustum pile consisting of several grades of material. Materials may be added to the stockpile until the base area of the stockpile is fully utilized. Reclaiming action of the leveling apparatus will reclaim layers of the varying grades of material, while in the process, blending the different grades into a new homogenous material composed of percentages of the grades that make up the stockpile. 
     The open stockpile management system may of course be enclosed with a lightweight low cost metal clad type structure providing weather or environmental protection should this at any time become necessary or desirable. 
     The reclaiming method and apparatus of this invention may be used to advantage with conventional silos and constitutes a further invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS. 
     FIG. 1 is a side view of a storage facility made in accordance with one aspect of this invention and shown partly cut-away; 
     FIG. 2 is a plan view of one form of a rotary scraper assembly; 
     FIG. 3 is a part sectional view showing the upper loading details of a storage container; 
     FIG. 4 illustrates the peripheral support mechanism for the rotary scraper; 
     FIG. 5 illustrates an alternate form of peripheral reclaiming apparatus for reclaiming material from a storage container; 
     FIG. 6 is a cut-away side view of an alternate form of storage facility utilizing a central material discharge; 
     FIG. 7 corresponds to FIG. 6 but illustrates a further discharge arrangement; 
     FIG. 8 diagrammatically illustrates one form of friction drive for rotating a rotary scraper; 
     FIG. 9 diagrammatically. illustrates an alternate form of friction drive; and 
     FIGS. 10 and 11 illustrate the rotary scraper support and slide arrangement in plan and side views respectively; and 
     FIG. 12 shows a sectional view of the open stockpile and illustrates the support of the leveling/reclaim apparatus by sheaved counterweight systems which may apply at either the perimeter only or for application at larger installations at both the perimeter and the center; and 
     FIG. 13 is a sectional view that illustrates the manner in which the leveling and reclaim apparatus is supported by the outer annular perimeter truss. The truss is slideably attached to the reaction column. The leveling/reclaim apparatus is shown with a series of perimeter support rollers Support at the center would be similar with an inner annular truss arrangement; and 
     FIG. 14 illustrates the friction drive assembly positioned on the leveling/reclaim apparatus, drive assembly is shown dotted. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The storage apparatus  10  is in the form of a low profile container  11  having a low pitched roof  12  supported by a container wall  28  and centrally by a large diameter central column  13 . A series of guide post assemblies  14  are arranged vertically about the inside periphery of the container  11  and rotary support apparatus  15  are engaged with the post assemblies  14  for vertical movement along the posts and support of the peripheral edge of the rotary scraper  16 . The material is introduced over a spreading cone  23  from a feed conveyor  27  and discharged from a peripheral reclaiming chamber  29  adjacent the container wall  28 . 
     In the illustrated embodiment, the container is an eighty meter diameter container with a wall height of about 20 meters and is adapted to contain about 80,000 tons of mined or manufactured granular material, such as bauxite or map dap fertilizer. The rotary scraper  16  illustrated in FIG. 2 has a series of radial arms  17  which extend from an inner annular hub  18  to an outer annular rim  19  which support scraper blades  20  in a suitable arrangement thereon. The blades  20  extend downwardly from the underside of the arms  17  so as to engage the top surface of material contained in container  11 . 
     As illustrated in FIG. 4, the outer rim  19  includes an angle section member  21  having a vertical web which provides radial location against the centering rollers  24  supported by the rotary support apparatus  15  and a horizontal web  25  providing vertical support on the horizontal centering rollers  26 . Both the rollers  24  and  26  are arranged for free rotation about their respective axes and are supported on each rotary support apparatus  15 . 
     The inner face of the vertical web  22  is also formed as an annular gear which meshes with a driven gear  30  mounted directly on the output shaft of a motor/gearbox assembly  31  mounted on the rotary support apparatus  15 . In order to resist the torque applied to the rotary support apparatus  15  by the drive motor  31 , each guidepost assembly  14  includes spaced apart posts between which the rotary support apparatus  15  engages. Each rotary support apparatus  15  is suspended from the upper edge of the container by a remotely operated hoist, all of which are operated simultaneously so that the rotary scraper  16  can be raised and lowered to a selected position. The inner hub  18  rotates freely about the central column  13 . FIG. 3 illustrates the central column  13  extending upwardly to provide an equipment deck  35  adjacent the roof and upwardly therebeyond to support the roof and to support the discharge chute  36  and upper end of the loading conveyor  37 . If desired, a transfer conveyor  38  may also be supported to take the product to an adjacent storage facility once the container is full. A flap valve  40  is provided for directing the flow either to the transfer conveyor  38  or the discharge chute  36  for discharge upon a cone shaped spreader cap  41  from which granular material flows into the container. 
     As shown in FIG. 5, discharge from the base of the container  11  is achieved through a reclaiming chamber  42  adjacent the sidewall  43  of the container  11 . A first belt-type  45  conveyor or feeder unit transfers material falling through the inlet  44  to an outloading conveyor  46  which elevates the material to a desired delivery station. 
     The storage apparatus  60  illustrated in FIG. 6 utilizes a centrally arranged auger  61  disposed within the central open structure column  62  about which material to be stored is introduced via a distribution cone  63  adjacent the column structure  62 . The auger  61  has a center shaft  65  supported by bearings  66  at its ends, and where so dictated by engineering design at suitable intermediate positions along its center shaft  65 . The bearings  66  allow the auger to rotate about its axis. The auger  61  is belt or chain driven by an electric motor  67  which is positioned adjacent the lower bearing  66  for suitable maintenance or service access away from the discharge port  68  at the base of the auger  61 . 
     The apparatus  70  illustrated in FIG. 7 is a variation on the apparatus  10  of FIG.  1 . In this form a reclaim tunnel  71  extends across the base of the container  72  so as to be fed gravitationally from opposed peripheral reclaim chambers  73 . As in the earlier embodiments feed is introduced axially from an inload conveyor  75  which dumps onto the apex  76  of the distribution cone  77  for even distribution thereabout. A conveyor  78  is supported in the tunnel  71  for transferring material fed through the chambers for discharge as required. 
     In use, in each of the above storage apparatus the feed distributed about the distribution cone will tend to pile up around the central column. However rotation of the rotary scraper in one direction will engage the scraper blades with the sloped face of the piled material and feed it outward until the sloped face is levelled. The rotary scraper is then raised to feed any further material supplied about the column toward walls of the container until the container is filled to the uppermost level of the rotary scraper. 
     When discharging material, gravity feed will initiate feed material to the central reclaiming station or the peripheral reclaiming station or stations. The material which remains, either against the walls in the case of a central discharge, or about the column in case of peripheral discharge can then be fed toward the respective reclaiming station by lowering the rotary scraper to engage the top of the remaining material and rotating it in the reverse direction to feed material inward to the column for discharge, or in the same direction for feeding material to peripheral discharge stations. The rotary scraper may be lowered to a position adjacent the floor so that practically all material is discharged. 
     FIGS. 8 and 9 show alternate friction drives for peripherally driving the rotary scraper  100 . In FIG. 8, the top annular chord  80  of the rotary scraper  100  is provided with a drive flange extending thereabout. A reversible friction drive wheel  82  is engaged with the flange  81  for rotating the rotary scraper  100 . 
     The wheel  82  is driven from a motor  83  carried by a pivot bracket  84  mounted on a slide plate  85  moveable along one of the peripheral guide post assemblies. The slide plate  85  also carries the lower reaction wheel  89  on a further pivot bracket  86  which may be pivoted upwards by a selectively operable ram  87  and linkage  88  to clamp the flange  81  between the friction wheel  82  and the reaction wheel  89  so as to regulate the driving force transferred to the rotary scraper. Thus the rotary scraper  16  may stall if undue loads are applied thereto such as by forcing the scraper too deeply into a pile of material to be levelled, without damaging the motor or drive. 
     In the arrangement illustrated in FIG. 9, each radial truss  90  from which the scraper blades are suspended carries a round-section ring  91 ,  92  at the and of its upper and lower chords  93 ,  94 . A friction driving wheel  95  engages a flange mounted on the top ring  91  and a reaction wheel  96  supports the lower ring  92 . The reaction wheel is supported directly on the slide  97  while the drive wheel  95  extends, from a motor/gearbox assembly supported pivotally from the slide  97  and adjustably by the selectively operable ram  98  which is used to regulate the driving force applied to the rotary scraper as described above. 
     The slide  97  as illustrated in FIG. 10 has opposed vertically extended angle rails  103  which engage captively through slide blocks  101  about the diagonally arranged square-section rails  102  which form the vertical chords of a composite post assembly  105 . Opposed pulley wheels  106  supported at the top of the slide  97  enable the slides to be raised and lowered by hoist cables, not shown, which extend between the wheels  106  on the slide  97  and the wheels  110  supported at the top of the post  105  and driven by an electric winching arrangement  111  for raising and lowering the slide. The vertical rails  102  are connected to the sidewall, shown dotted at  112 , through stand-off mounting brackets  113 . 
     The winches used to raise and lower the rotary scraper are preferably positioned atop the guide posts and spaced evenly about the periphery of the container. Additional winches may be provided intermediate the guide posts if desired and such as may be required for very large diameter containers where there may be a significant span between adjacent posts. Alternatively multi-stage pneumatic rams or the likes may be used as the means to raise and lower the rotary scraper. 
     From the above it will be seen that the overall height of the container is relatively low and this facilitates filling of the container. Furthermore the use of a spreader enables the container to be filled to capacity and completely emptied, thus effectively using the space for storage. In addition all processing is achieved without the need for supervised machinery such as front end loaders. 
     The open stockpile management system illustrated in FIGS. 12-14 is in the form of a circular area  114  having a series of equispaced perimeter support structures  115  that provide support to the outer circular support truss  116  upon and in which the leveling/reclaiming apparatus  117  is supported and rotates. 
     A central support and distribution column  118  is used to support an inner circular truss  119  in which the leveling/reclaiming apparatus  117  is also supported. The inner and outer circular trusses  119  and  116  are counterweighted by weights  120  and  122  to provide equality of mass between the combined weight of the trusses and the leveling/reclaim apparatus and the counterweights. 
     Height adjustment required during operation of the stockpile management system, is provided by a central hydraulic ram  121  positioned underneath counterweight  120  Material is deposited in conventional manner by a conveyor system depositing materials via a centrally positioned chute  123  over distribution cone  124 . Rotation of the leveling /reclaim apparatus will engage a series of scraper blades  125  positioned to move material outward. The apparatus  117  may during fill operations be positioned in its topmost location. Continual filling may be with material of consistent quality and grade but could also be with varying grades which would result in the stockpile having layers of varying grades  126 . 
     Outward scraping blades  125  will only promote the material outward to the point of intersection between the top level of the pile  127  and the top of the angle of repose  128  and produce the frustum shaped pile embraced by the base area  114  and the angle of repose  128 . Reclaim pockets  129  are located on the center-line and positioned in the base  114  coincident with a point vertically below the top of the angle of repose  128 . Inward grading blades  130  ensure that with operation of the management system. by rotation of the apparatus  117  the outer material will progressively be reclaimed. 
     With reference to FIG. 13, rotation of the leveling/reclaim apparatus is by means of a series of rollers  131  fitted at even spaces to the perimeter of the apparatus  117 . The rollers are supported in the inner and outer circular trusses  119  and  116 . The circular trusses  119  and  116  are supported by a cable arrangement via sheave sets  132 . With reference to FIG. 14, rotational drive power is provided with a motor/gearbox arrangement  133  that provides friction drive power to the friction face  134  of outer circular truss  116 . 
     Combined reaction and guiding attachments  136  transfer drive reaction forces to towers  115  and provide guides for vertical travel. 
     Thus it will be seen that this embodiment enables large volumes of granular bulk solids material to be readily managed in an automated fashion in respect of the stockpiling and-reclaiming of these materials. 
     While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.