AU2003229100B2 - Particulate material storage structure - Google Patents

Description

WO 03/097492 PCT/AU03/00640 PARTICULATE MATERIAL STORAGE STRUCTURE FIELD OF INVENTION This invention relates to a particulate material storage structure. More particularly, this invention relates to a partially underground storage system. 5 BACKGROUND ART The following discussion of the prior art is not intended to be, nor should it be interpreted as, an indicator of the common general knowledge pertaining to the invention, but rather is to be understood to give an indication of the developmental process which led to the invention. 10 Particulate material may be granulated. Such material includes rice, polymer beads and cereal grains. Such material is known to be stored in silos or other bulk storage facilities to protect it from (i) contamination such as by moisture, fungi, foreign matter, (ii) degradation caused by temperature fluctuations or solar exposure, or (iii) infestation from pests such as weevils, mice and the like. 15 A bulk storage facility located partially underground is described in AU 522872 (Vidal). AU 522872 discloses a bulk storage facility having inclined side walls 34 supported by artificially placed particulate material 23 and end walls 32 supported by artificially placed particulate material 45 and reinforced by steel elements 44 installed in layers of the particulate material 45. The walls of the structure are made from prefabricated 20 concrete panels such as facing elements 40 forming part of the end wall 32. At the base apex of the structure there is provided auger agitation meats to prevent blockages in the opening 38 which feeds reclaimed bulk material onto a conveyor located in a tunnel 24. The bulk storage facility is not cornpartrnentalised and it would be difficult to achieve regular exposure to all of stored bulk material for treatment thereof to overcome problems 25 associated with contamination, degradation or infestation. It is an object of this invention to inter alia ameliorate one or more of the disadvantages of the above mentioned prior art. STATEMENT OF INVENTION Accordingly, in one aspect the invention provides a partly subterranean particulate 30 storage structure for storing particulate material, the storage structure including: (a) at least first and second compartments; WO 03/097492 PCT/AU03/00640 2 (b) delivery means for selectively delivering the particulate material to each of the compartments one at a time; (c) conveying means for conveying the particulate material from a closable outlet at a base of each said compartment to a location above ground; 5 (d) at least one subterranean downwardly inclined wall terminating at the base and an upwardly extending wall, wherein at least one partition wall divides the first and second compartments. The particulate material may be granulated material and includes any material capable of forming discrete particles suitable for stockpiling. Examples include (i) mineral ores 10 such as coal, (ii) agricultural and industrial chemicals such as super phosphates and (iii) agricultural products such as rice and wheat. The subterranean downwardly inclined wall of the storage structure is preferably supported by a solid mass of earth or rubble. The earth or rubble may be pre-existing and may be excavated. Alternatively, the earth or rubble may be built up to form a supporting 15 inclined surface on which the inclined wall may be located. Preferably, the surface bearing the downwardly inclined wall is excavated from pre-existing earth. Preferably, the angle of inclination of the inclined wall is relatively shallow to decrease or obviate the need for reinforcing means to prevent land slippage. Preferably, the excavated earth is compacted to decrease or obviate the occurrence of subsidence under load once the storage structure is 20 fully installed. Preferably the angle of the downwardly inclined wall is 25 to 40* relative to the horizontal. Still more preferably, the angle of inclination of the downwardly inclined wall is 28 to 300 to the horizontal. However, it will be appreciated that preferably the downwardly inclined wall has an angle of inclination substantially corresponding to the angle of repose of the particulate material. Accordingly, the angle of inclination of the 25 downwardly inclined wall is dependent on the settling and flow properties of the particulate material and may be varied accordingly. The downwardly inclined wall may form an inverse pyramidal conical structure. However, preferably the structure includes at least two symmetrically opposed planar walls converging to the base. The base may extend linearly along a substantial portion of the 30 length of the structure. The base may terminate in one or more openings in communication with a subterranean tunnel. The tumnel may extend parallel to the base. The tunnel may shadow at least the length of the base. The tunnel may be in communication with the above WO 03/097492 PCT/AU03/00640 3 ground surface by means of a maintenance shaft which extends from a proximal end of the tunnel closest to particulate material supply lines up to the ground surface. The tunnel may house the conveying means. The conveying means may include any suitable means for receiving dispensed particulate material via the opening and conveying it 5 to an end point, Accordingly, chain conveyors, bucket conveyors, trolleys, optionally adapted to travel along rails, and many other alternatives would be effective to convey particulate material from the base outlet to the location above ground as a person skilled in the art would appreciate. Preferably, the conveying means includes a motor end drum endless belt conveyor extending along a linear length of the tunnel whereby to transport any 10 particulate material dispensed through the opening to a distal end of the tunnel. The conveying means may comprise a unitary means of conveying the particulate material to the ground surface or may include two or more transport means combined to effectively convey the material. For example, conveyance of the particular material through the tunnel may be achieved by an endless belt conveyor extending substantially horizontally through the 15 tunnel. Elevation of the particulate material from the distal end of the tunnel may be achieved by elevation means. The elevation means may include any suitable means for lifting the particulate material from the distal end of the tunnel to the ground surface and includes lift elevators, vacuum means and augers. The lift elevator may include a plurality of buckets as is 20 standard in the art whereby buckets hinged to an inclined chain conveyor receive convey and dispense discrete amounts of particulate material per bucket from the distal end of the tunnel to the ground surface to be received by, for example, a truck or lorry adapted for bulk loads, or a railway truck for transport by rail. The ends of the structure may be inclined or substantially vertical walls, Preferably, 25 the proximal end of the structure includes a wall with a shallow gradient. In one embodiment, the proximal end of the structure comprises a moderately graded distal end wall extending from the base to ground level. The proximal end of the structure may alternatively include a sheer wall which steeply extends from the distal end of the tunnel to the ground surface. The distal end of the structure may be similarly configured. Preferably, 30 the distal end of the structure includes a sheer wall steeply inclined and substantially vertical extending from near the distal end of the structure to a point above ground level, The end walls may be planar or may be convex. Preferably the end walls, particularly the sheer WO 03/097492 PCT/AU03/00640 4 distal end wall has an internally concave surface to better distribute the forces applied to it by the particulate material. Notwithstanding this, the sheer end wall may have an internally convex surface to dissipate forces applied by the particulate material to its lateral edges and thereby bear against excavated earth which is able to withstand the potentially large forces 5 applied by the particulate material. The sheer end wall may include reinforced concrete panels, supported by steel bearers or gussets, particularly if the conveying means continues behind the wall up to ground surface level, whereby behind the sheer wall there may be a hollow shaft. The storage structure above ground level preferably includes a roof. The roof may be 10 located in a single plane. Alternatively, the roof may include a pair of roof structures extending upwardly from the sides of the structure to an apex. The roof may extend from ground level up to the apex. Alternatively, the structure may include side walls extending above ground level to substantially increase the volume capacity of the structure as a whole. The structure above ground level may therefore be configured according to normal building 15 structure principles applicable to large warehouses or hangers and may include a steel frame. The compartments are defined by one or more partition walls located within the structure. The partition walls may be solid inflexible structures. However, it is preferred that the internal partition walls be made from flexible material. The partition wall may be 20 capable of flexing in response to the application of a load. The load may be such as that corresponding to the forces that may be applied by the particulate material. The partition walls may be made from light material, such as polymeric sheet material. The sheet material may be any one or a combination of a number of lightweight materials such as cork, fibreboard, fibreglass, polyethylene, polypropylene and the like. 25 Preferably, the sheet material is a sandwich panel. The sandwich panel preferably has a foam core. The sheet material may includes an abrasion resistant skin. The abrasion resistant skin is preferably hard wearing and may comprise a layer of plastic such as polypropylene, polycarbonate. The abrasion resistant skin may comprise an outer layer of metal. The metal skin may be steel or aluminium. For reasons which will be apparent in 30 relation to the following discussion of flex limiting means, the skin is preferably steel to resist abrasion by steel or other cables.

WO 03/097492 PCT/AU03/00640 5 The partition wall may be substantially vertical. The partition wall may extend from the base to a level intermediate the height of the structure. Alternatively, the partition wall may extend substantially the full height of the internal space of the structure in the area of the compartments. The partition wall may be defined in shape to correspond to the internal 5 shape of the structure whereby to provide a fully extended partition whereby to separate two adjacent compartments. The partition wall may normally in use be substantially vertical, The partition wall may extend substantially laterally across said structure. The partition wall may be movable within the structure. The partition wall may be movable from a first position within said 10 structure to a second position, This may be effective to vary the volume of the first compartment and/or the second compartment. The partition wall may be adapted to reciprocate within the internal space of the structure in a longitudinal direction. Where the structure includes a roof truss or upper frame extending into the internal spaces and the partition wall fully extends up to the upper region of the roof area, this may 15 cause a problem. Moreover, where the partition wall is to be moved in a longitudinal direction from one position to a second position within the internal space of the structure, the roof truss or frame may present an obstruction. For example, a bottom chord or strut of the truss, such as a lateral compression beam, may impede the movement of the partition wall from the first to the second position. To overcome this, the partition wall may be 20 adapted to pivot about a central axis extending through the plane of the partition wall intermediate its height. The partition wall may include a pivot point located on each side. the pivot points may be reinforced in the area of the partition wall adjacent the pivot points whereby to be capable of bearing the load of the partition wall as it rotates about the pivot points. 25 By so pivoting the partition wall, the top region of the partition wall which would otherwise run into the truss beam when being moved, instead pivots underneath and is righted to a substantially vertical orientation only when the partition wall has moved under and is clear of the truss beam. The pivot points may be engaged in tracks which run along the respective sides of the structure. 30 The partition wall may be mounted on running means to facilitate movement of the partition wall. The running means may include rollers engaging the structure at or near the WO 03/097492 PCT/AU03/00640 6 base. For example, the rollers may be in the form of a pair of rollers which straddle the conveying means. Preferably, the structure includes flex limiting means. The flex limiting means may be adapted to limit the flexion of the partition wall. The flex limiting means may include 5 solid or rigid structures which prevent the partition wall from collapsing under the load of particulate material in an adjacent compartment, Alternatively, the flex limiting means may pennit the partition wall to flex whereby to disperse the load applied to the wall by permitting the partition wall to assume a concave configuration. The flex limiting means may include a cable capable of high tension. The flex 10 limiting neans may include one or more high tension cables. The high tension cables may be anchored to anchor points at the periphery of the structure. The high tension cables may be releasably engageable to the anchor points. The anchor points may be located at ground level, The anchor points may include multiple anchor points such as eyelets and/or hooks located at spaced intervals along the side walls of the structure. The anchor points may 15 include a plurality of anchor points arranged in a grid pattern to permit the flex limiting means to extend from a variety of points. This may be both along a horizontal line along the side wall and/or a vertical line up the side wall. The flex limiting means may include one or more cables which extend laterally across the width of the structure. The flex limiting means may be oriented substantially horizontally or diagonally or a number of cables may 20 be oriented collectively in a combination of both. Preferably, the flex limiting means includes a number of vertically spaced, substantially parallel cables extending either side of the partition wall. Alternatively, the flex limiting means may be located centrally within the partition wall purpose built for the structure. Preferably, the flex limiting means is located either 25 side of the partition wall so that the flexion of said partition wall in either direction transverse to the general plane of the partition wall is limited. The anchor points may include pylons embedded in the surrounding earth and are preferably concreted into position. The pylons may provide support for the roof of the structure. The cable may be steel cable. The cable may be draped across the compartment 30 and not be under tension unless a load is applied to the partition wall. Preferably, however, the cable is held at high tension to minimise the distortion of the partition wall upon application of a load thereto. The high tension cable may extend vertically, horizontally WO 03/097492 PCT/AU03/00640 7 and/ox diagonally across the structure. Preferably, the cable extends horizontally across the structure. The partition wall may include a pair of panels. The pair of panels may be located either side of the flex limiting means or other reinforcing means. Alternatively, the cable 5 may be embedded during manufacture or installation in the partition wall comprising for example a single sheet or panel. The delivery means may extend along the peak of the roof. The delivery means may be aligned longitudinally relative to the structure. The delivery means may include an overhead conveyor, The conveyor may be an endless belt conveyor. The delivery means 10 may include selective means for selectively delivering particular types of particulate material to selected compartments. The selective means may be movable from one delivery point to another corresponding to one compartment or another. The selective delivery means may include a conveyor on a trolley. The trolley may be movable along a track. The selective delivery means may include a tripper conveyor system. The conveyor means may 15 be located in a conveying shaft at the apex of the roof of the structure. One or more compartments may include agitation means. The agitation means may be adapted for recirculating the particulate material within each said compartment to shift particulate material located near the base to the top of the pile of particulate material in the compartment. The particulate material may be prone to clumping and blocking near the 20 opening at the base. For example, heat or pressure sensitive material such as polymer material may tend to fuse or otherwise undesirably clump together, particularly under the pressure of the particulate material above. It will be appreciated that where quantities of around 1000 tones are contained in a particular compartment, the pressure near the base can be considerable. Particulate material which is moisture sensitive, such as cereals, may 25 also tend to clump at the base. Moreover, it is desirable to turnover the particulate material where the particulate material is required to be regularly treated to prevent contamination, degradation, or infestation such as may result from fungi or bacterial degradation. Accordingly, treatment means may be located in the structure above the particulate material whereby to dispense treatment, such as may be in the form of a spray, onto the particulate 30 material. The agitation means facilitates a more even application of treatment to the whole of the particulate material stored and promotes drying to combat problems associated with the exposure of particulate material to heat, moisture and pressure. Preferably, the agitation WO 03/097492 PCT/AU03/00640 g means includes elevation means. Preferably, the agitation means operates in a shaft, such as a substantially vertical shaft. The shaft may be reinforced against internal collapse. Where an auger is used, the shaft may lightly abut against the auger and particulate material contained within the lines of the auger so that the particulate material raised by the auger is 5 not subject to fall back and the frictional forces against the rotation of the auger are minimised. The agitation means may therefore be in the form of an auger sheathed in a shaft the internal surface of which lightly abuts said auger along its length. In one embodiment of the storage structure, the conveying means may include an elevating means for raising particulate material from the compartments to an elevated 10 distribution means above ground, the distribution means being operative to selectively direct material either to a discharge point or to delivery means to direct material into the storage structure. In this embodiment, there is preferably a supply station where initial supply of material to be stored in the structure is delivered to the elevating means at a location intermediate. the section where the conveying means conveys material from the 15 compartments and the elevated distribution means. The dimensions of the structure may vary considerably. The structure may be of the order of 100 to 500 metres long and 20 to 100 metres wide at ground level. The subterranean walls may be 12 to 70 metres deep. In a particularly preferred embodiment, the structure is 500 metres long, 70 metres wide at ground level, the peak of the roof is 20 20 metres above ground level and the subterranean side walls extend 40 metres from the ground level to the base. The structure is preferably substantially weatherproof, including waterproof. The subterranean inclined side wall is preferably lined with a waterproof material. The waterproof internal surface of the side wall may be a sprayed cementitious mix. The 25 internal surface may be made up of concrete panels. The internal surface may include flexible metal or plastic sheets. Where the particulate material includes food matter, it is necessary to use an internal surface which is food safe. In like manner, depending on the chemical nature of the particulate material, particularly preferred internal surfaces may have predetermined chemically inert characteristics to safely or economically store the relevant 30 material. In a preferred embodiment, the side walls are merely excavated earth lined with plastic sheeting, such as black PVC lining. This is effective for many applications and is WO 03/097492 PCT/AU03/00640 9 extremely economic to install compared to prior art alternatives requiring the placement of substantial self-supporting or artificially placed structures. BRIEF DESCRIPTION OF THE DRAWINGS So that the invention may be more readily understood, one or more embodiments of 5 the invention will be described by way of illustration only having regard to the drawings where: Fig. 1 is a transverse section side elevation view of a storage system according to one embodiment of the invention; Fig. 2 is a transverse section end elevation view of the embodiment shown in Fig. 1; 10 Fig. 3 is a transverse section end elevation view of a second embodiment of the invention; Fig. 4 is a schematic side view of a trigger mechanism according to one embodiment; Fig. 5 is a transverse end elevation view of a storage system shown in Figure 2, but in greater detail; 15 Fig. 6 is a transverse side elevation view of a third embodiment; Fig. 7 is a transverse side elevation view according to a fourth embodiment; Fig. 8 is a transverse end elevation of a storage system according to another embodiment; and Fig. 9 is a longitudinal sectional view of a yet further embodiment. 20 DETAILED DESCRIPTION OF THE DRAWINGS In Figures 1, 2 and 5 there is shown a particulate material M storage system 10 including a delivery means in the form of an overhead delivery conveyor 20 located in a delivery conveyor shaft 30 extending horizontally along the apex of the roof 40 of the structure 10. The roof 40 is substantially an A-frame structure including a steel frame 41 25 mounted onto side pylons 50 which are embedded into the ground at 51 wherein they are concreted into place and optionally reinforced by large steel bolts 52. The steel frame 41 is tapered towards the apex of the structure 10 to minimise the amount of material used in the frame and reduce the overall weight of the frame 41. The roof end walls are made from standard materials, such as corrugated iron optionally replaced strategically with skylight 30 materials such as perspex to provide natural daylight. The above ground vertical side walls standing in the plane of the pylons 50 are reinforced by the steel frame of the above ground WO 03/097492 PCT/AU03/00640 10 structure which may include horizontal or diagonal cross beams extending between the pylons 50. At lower ground level G the ground is excavated to form a shallow V-shaped channel extending substantially the length of the structure 10. The channel 60 is defined by symmetrically opposed and downwardly inclined side walls 70 comprising black PVC 5 plastic film sheet covering the earth lining the channel 60. The underground walls 70 converge at a base 80. The base 80 includes a pneumatically operated valve opening 81 in communication with a tunnel 90 which houses a reclaiming conveyor 100. The proximal end of the structure 10 includes an eud wall 110 with a similar inclination to the underground side walls 70. Underneath the proximal end wall 110 is a 10 reinforced maintenance shaft 111 providing access to the reclaiming conveyor 100. The distal end of the storage structure 10 includes a concrete wall 120 reinforced by triangular gussets 121. At the distal end of the structure 10 the tunnel 90 terminates at a steeply inclined shaft 130 housing a bucket chain elevator 131 adapted to lift particulate material M deposited on the reclaiming conveyor 100, motorised by motor and drum 105, 15 into the individual buckets 132 and taken to a transport means at just above ground level G. Within the structure 10, the internal space is compartmentalised by one or more internal partition walls 140. The partition walls 140 comprise a double layer of flexible polymer material defining a narrow cavity therebetween. In the cavity 141 there is located an internal tension cable 142 at about ground level G. The internal cable 142 extends between 20 pylons 50 at which the ends of the cable are anchored and are operative to prevent either panel 143 or 144 unduly flexing under load. Agitation means 150 is provided in the form of an auger 151 operating within a chute 152 which extends from just above the pneumatic valve 81 to a height just above the anticipated highest level P that the particulate material M is anticipated to reach. The 25 agitation means 150 operates as an agitator, as an unblocker to the valve 81 and as a recycling means ensuring that, over an extended period of time, the particulate material M is satisfactorily mixed, For cereals such as wheat and rice, it is standard practice to spray the particulate material M for fungicides and the like to extend the life of the grain. Accordingly, depending from the delivery conveyor chute 30 or the internal steel frame of 30 the structure 10 are spray means 160 which may be in communication with external tanks containing a sprayable treatment composition adapted to be pumped to the spray means 160, The sprayers 160 may also be in selective communication with an external water source WO 03/097492 PCT/AU03/00640 11 which may be activated to spray water in the event of undesirable combustion. For example, coal dust is well known to be prone to spontaneous combustion in favourable conditions. The partition walls 140 may extend fully the height of the structure 10 or may 5 terminate intermediate the height of the structure as shown at 145. The shorter partition wall 145 permits ventilation of the compartments whereby to reduce moisture damage and fungi attack. The delivery conveyor 20 includes a tripper conveyor 170 shown in Figure 4. The tripper conveyor 170 is mounted on trolley wheels 171. The trolley mounted tripper 10 conveyor 170 may be moved from one delivery chute 172 to another whereby to selectively deliver particulate material to a particular compartment. For example, the storage structure 10 may be used to store various cereals such as wheat, rice and com which are discretely stored in the various compartments. The particulate material storage system is controlled overall by an integrated 15 computer system operable by an'operator and configured to activate various components as appropriate. For example, the compartments may include smoke detectors and/or temperature sensors which provide feedback as to whether water sprinklers should be activated. The computer system is adapted to control the movements of the tripper conve'yor trolley 171 to determine the particular compartment to which particulate material 20 travelling along conveyor 20 is delivered. The tail drum end conveyor 100, pneumatic valves 81 and bucket elevator 130 are controlled for coordinated operation. Blockage sensors may be positioned at the base 80 providing feedback for the agitation of the particulate material by the turnover means 150, A preferred method of installation will now be described. In some jurisdictions, 25 work, health and safety regulations mandate that working heights of 20 metres or greater be attended with significantly increased health and safety requirements. This significantly increases the costs of installation due to increased equipment and time delays. Accordingly, this method seeks to avoid requiring workers to operate at heights having a clearance of greater than 20 metres to the next level. Accordingly, the method may include, not 30 necessarily in order, the following steps: 1. assemble roof 40 in situ. In a preferred embodiment, the apex of the roof 40 is set at a height of 20 metres higher than the peripheral edges of the roof 40; WO 03/097492 PCT/AU03/00640 12 2. optionally install pylons 50 with lower portions 51 embedded in the earth and optionally reinforced with bolts 52; 3. optionally raise roof 40 and mount on the pylons 50; 4. excavate the earth to obtain the V-shaped channel 60 and optionally the distal and 5 proximal end walls 120, 110; and 5. excavate and reinforce the tunnel 90, maintenance shaft 11, and elevator shaft 133; 6. optionally build the distal concrete wall 120; and 7. optionally lay the plastic sheeting forming the internal surface of inclined subterranean side walls 70, 10 The inclusion of the vertical side wall structures 50 above ground in structure 10 may effectively double the amount of particulate material M which may be stored in a particular structure. An alternative structure 200 is shown in Figure 3 in which the vertical above ground side walls 50 of structure 10 are dispensed with such that the peripheral edges of the roof 40 are supported at ground level. This significantly decreases the cost of installation 15 due to the absence of the pylons 50 and the requirement to lift the assembled roof structure onto the pylons during installation. However, it is still necessary to establish anchor points at ground level embedded in the earth surrounding the excavated chawnel 60 to provide anchor points for the high tension cables 142 supporting the one or more partition walls 140. 20 Referring to Figure 6, the third embodiment shown is similar to that shown in Figure 1. The partition walls 141 extend the full height of the internal space of the structure 210. Figure 6 shows a trolley 173 which runs on tracks along the apex of the roof 40. The trolley 173 carries the trigger conveyor or belt inverter 170 adapted to selectively dispense particulate material in a particular compartment 220 through the chute 172. At the base of 25 the compartment 220 is a sliding metal plate 221 with a simple cut-out opening (not shown). Controlled by pneumatic rams, the sliding plate 221 is moved longitudinally along the base 80 to selectively dispense particulate material onto the reclaiming conveyor 100. In Figure 7, compartment 220 is shown with the addition of a lift auger 151 adapted to agitate the particulate material M. 30 In Figure 8 a storage structure according to another embodiment is shown. the structure includes an in-load conveyor with a belt inverter distributor 301 effective to deliver the particulate material to a selected compartment. The perimeter 302 of the WO 03/097492 PCT/AU03/00640 13 segregation or partition wall (in the plane of the sheet of the drawing) is defined by a fundamentally hexagonal shape. A baffle cap 303 is provided to reduce the gravitational pressure of the granulated or particulate material on a sliding valve 306. Wheels 304 at the base of the partition wall enable the partition wall to be moved from one position to another 5 to change the capacity volumes of the compartments. The conveyor housing 305 can be constructed from many different materials suitable for the purpose. For example, the conveyor housing 305 may be made by ramming and compacting earth following excavation, from steel or from concrete. The valve slide 306 may be pneumatically or hydraulically controlled, preferably using a pneumatic ram. A 10 retrieval conveyor 307 is shown which takes particulate material from gravitational feed from the base via the valve slide 306 and delivers the particulate material to a waiting transport at ground level as described in relation to reclaiming conveyor 100. The structure includes a roof 311 including roof cladding, The roof may be set at a suitable inclination, preferably 32 degrees pitch, The roof frame includes a top chord 312 of 15 the truss and a compression beam or strut 308 which forms the bottom chord of the truss. Because the partition wall when vertical extends above the compression beam 308, to move the partition wall ppst the compression beam 308, it is necessary to either dismantle the top portion of the partition wall or, preferably, to pivot the partition wall about a horizontal axis and move the partition wall past the compression beam 308. Accordingly, the partition wall 20 is provided with pivot means intermediate its height on each of its sides which movingly engage with the side walls such as along tracks for the purpose. Where the partition wall is to be moved between adjacent compression beams 308, the partition wall remains vertical and is pushed along on its wheels 304. The structure 300 is provided with side pylons or columns 310 and spaced intervals 25 along the length of the structure 300. These pylons 310 are used to mount anchor points for high tension cables 309 acting as flex limiting means. Three pairs of horizontal and parallel high tension cables 309 are shown. Each pair is located either side of the partition wall so that the wall is fully supported throughout its height and width. The cables 309 may be released and relocated to different locations depending on where the partition wall is to be 30 located. In Eig. 9 the reclaiming conveyor 100 delivers particulate material to the bucket chain elevator 131 as in other embodiments. However in this embodiment the bucket chain WO 03/097492 PCT/AU03/00640 14 elevator 131, instead of delivering material to just above ground level, delivers the material to an elevated distribution head 410 from which the particulate material may be discharged tbxough chute 412 tbe transport vehicle 415. The distribution head 410 includes a diverting valve 420 which can be selectively switched between two operative conditions, in one of 5 which the particulate material is delivered through chute 412, In the other condition, the valve 420 directs material elevated by bucket chain elevator 131 through path 425 to the delivery conveyor 20 at the top of the structure 10. This embodiment enables the elimination of the supply conveyor indicated by numeral 250 in Figs 6 and 7 through which material is initially supplied in these embodiments, with associated cost savings. In 10 particular, the material can be supplied from supply transport vehicle 430 at supply station 432 through chute 435 to the elevator 131 for initial supply to the structure 10, with the bucket chain elevator 131 also being used for discharge of stored material to vehicle 415. The diverting valve 420 can be normally held in its condition to direct material to the delivery conveyor 20 whereby inadvertent operation ofthe conveying means 100, 130 15 merely recycles material back to the structure. When used in this specification and claims, the terms "comprises" and "comprising" and,variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

Claims (12)

1. A partly subterranean particulate storage structure for storing particulate material, said storage structure including: 5 (a) at least first and second compartments; (b) delivery means for selectively delivering said particulate material to each of said compartments one at a time; (c) conveying means for conveying said particulate material from a closable outlet at a base of each said compartment to a location above ground; 0 (d) at least one subterranean downwardly inclined wall tenninating at said base and an upwardly extending wall, wherein at least one partition wall divides said first and second compartments.

2- A storage structure according claim 1, wherein said partition wall is in use substantially vertical and extends substantially laterally across said structure.

3. A storage structure according claim 1, wherein said partition wall is pivotable to facilitate 5 movement of said partition wall from a first position to a second position in said structure.

4. A storage structure according claim 3, wherein said partition wall is pivotable about a horizontal axis.

5. A storage structure according claim I, wherein said partition wall is capable of flexing in response to the application of a load. .O 6- A storage structure according to claim 1, wherein said partition wall is made from polymeric sheet material of one or more sandwich panels having a foam core and an abrasion resistant skin.

7. A storage structure according to claim 1, wherein said partition wall is movable from one position within said structure to another, whereby to vary the volume of said first compartment 25 and/or said second compartment.

8. A storage structure according to claim 7 wherein said partition wall is mounted on running means to facilitate said movement.

9. A storage structure according to claim 8, wherein said running means includes rollers engaging said structure at or near said base. 30 10. A storage structure according to claim 1, wherein said structure includes flex limiting means to limit the flexion of said partition wall.

11. A storage structure according to claim 10, wherein said flex limiting means includes a cable capable of high tension. 16 12, A storage structure according to claim 11, wherein said flex limiting means is anchored to anchor points at the periphery of said structure. ) 11 A storage structure according to claim 12, wherein said anchor points are located at 5 intervals along the length of said storage structure and at vertical intervals along the side walls of said structure,

14. A storage structure according to claim 10, wherein said flex limiting means is located either side of said partition wall so that the flexion of said partition wall in either direction transverse to the general plane of said partition. wall is limited. 10 15. A storage structure according to claim 11, wherein said flex limiting means comprises two or more high tension cables releasably mounted to anchor points on the side walls of said structure.

16. A storage structure according to claim 1, wherein said delivery means includes a tripper conveyor system. 15 17. A storage structure according to claim 1, further including agitation means in the form of an auger sheathed in a. shaft the internal surface of which lightly abuts said auger along its length.

18. A storage structure according to claim 17, wherein said agitation means is operable intermittently or is selectively operable. 20 19. A storage structure according to any one of the preceding claims wherein said conveying means includes an elevating means for raising particulate material from said compartments to an elevated distribution means above ground, the distribution means being operative to selectively direct material either to a discharge point or to delivery means to direct material into the storage structure. 25 20. A storage structure according to claim 19 wherein there is a supply station where initial supply of material to be stored in the structure is delivered to the elevating means at a location intermediate the section where the conveying means conveys material from the compartments and the elevated distribution means.