Abstract:
Mobile conveyor modules are used for transporting aggregate over a long distance, or for transferring the aggregate to other modules, and for stacking the aggregate either linearly or radially. These modules may be used in various combinations by themselves or in combination with existing conveyor systems and bridge stackers to stack aggregate on and off multi-lift leach pads and on multi-lift dump sites. The mobile conveyor modules are designed to be steerable and self-propelled, providing increased maneuverability and reducing relocation/reformation time. Multiple stacking methods may be used with the mobile conveyor modules either separately, or at the same time, advance and retreat stacking, the stacking of a berm, or the filling in of a corridor, may be accomplished on a variety of terrain.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the movement of bulk materials, and more particularly, pertains to moving and stacking material, such as ore, coal, granite, clay, salt, and potash, generally referred to herein as “aggregate”, by mobile belt conveyor modules. 
     2. Description of Related Art 
     The present invention is concerned with depositing aggregate into piles, and more particularly is an improved system and method for depositing aggregate into multi-lift dump sites, such as heap leach stacks, waste dump sites, or material dump sites, for example. 
     Prior art systems that perform these functions generally employ material conveyors mounted on bridges or trusses called bridge conveyors, bridges, or mobile stacking conveyors. Articulated mobile conveyors having sections are known. Each section is separately movable relative to the ground. Such a system is described in U.S. Pat. No. 5,749,452 granted May 12, 1998 to Brian M. Kenwisher for Mobile Conveyor Including Alignment System. Very long, endless conveyor belt assemblies are also known for transporting loose particulate material over long distances. These conveyors are only moveable in a direction transverse to their length. Such a conveyor assembly is described in U.S. Pat. No. 4,206,840 granted Jun. 10, 1980 to Raymond D. Hanson for a Movable Belt Conveyor Assembly. 
     One of the problems with the conveyor systems of the prior art is that such systems take time to move any appreciable distance when a new stack is to be started. This is especially true when stacking aggregate which is to be subjected to heap leach processes. These processes are used, for example, to extract copper or gold from the stacked piles of aggregate or leach pads containing the metal or mineral of interest. 
     In today&#39;s world, mining is a basic industry in a global economy. Thus, regardless of the site of the mining or leaching operation, it must be conducted in a manner that minimizes capital costs, minimizes operating costs, and minimizes the delay time between stacking heaps and recovering the metals or minerals of interest. 
     Prior art multiple lift stacking systems using bridges, with either advance or retreat stacking require considerable down time, a great deal of additional earth work effort, and a considerable amount of labor to extend and retract the overland conveyor used in the process. The prior art stacking processes delay recovery of the metals or minerals of interest from the aggregate. In an ongoing leaching operation, for example, a major concern is to leach the newly stacked aggregate immediately. Thus, at the completion of any lift, a complete leach cycle time is scheduled before stacking the next lift so that the material can be leached to full economic advantage at each lift. These concerns, in general, require movement of the prior art systems that could be both wasteful and unnecessary. 
     A prior art attempt to solve such problem is described in U.S. Pat. No. 6,085,890 granted Jul. 11, 2000 to Ronald R. Kelly, et al. for Heap Leach Stacking Process. However, even this approach requires down time, a shortcoming which the present invention overcomes. 
     SUMMARY OF THE INVENTION 
     Multiple lift pad and dump site stacking is enhanced in flexibility and speed by the use of mobile stackers, mobile trippers, and mobile conveyor modules, which are carried by rolling stock, such as wheels or crawler tracks which are steerable. Some of these modules are also self-powered so they are driveable to the required locations. The combination of mobile conveyor modules bringing aggregate to a tripper for distribution to a bridge stacker and a radial stacker provides efficient multiple lift stacking of a leach pad or a general dump site. Berm building and corridor filling occur at about the same time as the lift stacking. Moreover, the self-powered mobility of the mobile conveyor modules and tripper modules considerably reduces down time when the modules must be relocated. 
     The invention utilizes a mobile belt conveyor module mounted for movement with respect to the ground on steerable rolling stock. A mobile belt conveyor with a tripper, “mobile tripper module” mounted for movement with respect to the ground on steerable rolling stock is fed aggregate by the mobile belt conveyor module. A mobile stacker is fed aggregate by the mobile tripper module to stack the aggregate to lift level. The stacking method of the present invention comprises advance stacking a lift berm for conveyor travel at about the same time the extension half of the lift is being advance stacked. The retraction half of the lift is also advance stacked, leaving a completely stacked lift without corridors to be filled. Alternatively, the stacking method of the present invention comprises advance and retreat stacking in the extension phase, creating a corridor for conveyor travel. Advance and retreat stacking in the retraction phase while also stacking the corridor, leaves a completely stacked lift without a corridor to fill. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The exact nature of this invention, as well as its objects and its advantages, will become readily apparent from consideration of the following detailed description in conjunction with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof and wherein: 
     FIG. 1 is a partial perspective schematic layout of an on/off leach pad and waste dump stacking scheme; 
     FIG. 2 is a perspective illustration of a mobile radial stacker; 
     FIG. 3 is a perspective illustration of a self-powered steerable mobile belt conveyor module with a tripper car, “mobile tripper module”; 
     FIG. 4 is a perspective illustration of a bridge stacker or mobile stacking conveyor; 
     FIG. 5 is a perspective illustration of a self-powered steerable mobile belt conveyor module; 
     FIG. 6 is a perspective illustration of a stacking scheme utilizing the radial stacker, the self-powered mobile tripper module, and the self-powered mobile belt conveyor; 
     FIG. 7 is an isometric illustration indicating an area topography before heap stacking has begun; 
     FIG. 8 is an isometric illustration indicating the disposition of stacking system components on an area topography at the beginning of a stacking cycle for the first lift; 
     FIG. 9 is an isometric illustration indicating the disposition of stacking system components on an area topography after the extension phase of first lift stacking has begun; 
     FIG. 10 is an isometric illustration indicating the disposition of the stacking system components on an area topography wherein a stacker is building a berm to lift grade elevation; 
     FIG. 11 is an isometric illustration indicating the disposition of stacking system components on an area topography when the first lift cycle has reached the end of the area furthest away from the material supply; 
     FIG. 12 is an isometric illustration indicating the disposition of stacking system components on an area topography during the retraction phase of first lift stacking; 
     FIG. 13 is an isometric illustration indicating the disposition of the stacking system components on an area topography when the first lift cycle is being completed; 
     FIG. 14 is an isometric illustration indicating the disposition of stacking system components on an area topography after the first lift cycle has completed and the stacking bridge is being rotated into a starting position for the second lift cycle; 
     FIG. 15 is an isometric illustration indicating the disposition of stacking system components on an area topography after the extension phase of the second lift cycle has begun; 
     FIG. 16 is an isometric illustration indicating the disposition of stacking system components on an area topography during the extension phase of the second lift cycle; 
     FIG. 17 is an isometric illustration indicating the disposition of stacking system components on an area topography when the second lift cycle has reached the end of the area furthest away from the material supply and the stacking bridge is being rotated and translated around the end of the area to prepare to begin retraction; 
     FIG. 18 is an isometric illustration indicating the disposition of stacking system components on an area topography during the retraction phase of a second lift cycle; 
     FIG. 19 is an isometric illustration indicating the disposition of stacking system components and the area topography during the retraction phase with a radial stacker filling in the corridor to lift grade elevation; 
     FIG. 20 is an isometric illustration indicating the disposition of stacking system components on an area topography when the second lift cycle is completed and the grade elevation is being tapered out against the topographic slope; 
     FIG. 21 is a schematic illustration of a stacking layout for a dump site showing disposition of the stacking system components during the extension phase of a lift cycle; 
     FIG. 22 is a schematic illustration showing the disposition of stacking system components on a dump site when stacking has reached the end of the area furthest away from the material supply and the stacking bridge is being rotated and translated around the end of the area to prepare to begin retraction; 
     FIG. 23 is a schematic illustration showing the disposition of stacking system components on a dump site during retraction; 
     FIG. 24 is a schematic illustration showing the disposition of stacking system components on a dump site at about completion of the retraction phase with a radial stacker stacking the corridor; 
     FIG. 25 is a schematic illustration showing the relocation of the stacking system components to an adjacent dump site; and 
     FIG. 26 is a schematic illustration showing disposition of the stacking system components in the retraction phase of a multiple lift stacking cycle on a third adjacent dump site. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates in three dimensions and schematically one of many possible layouts for an on/off leach pad stacking scheme adjacent to a dump site. The stacking of the leach pad and dump site is being accomplished by prior art equipment. The conveyor modules of the present invention are not being used. Leach pad  11  is typically designed to capture the leach liquid and it&#39;s dissolved recoverable minerals or metals. A discharge conveyor  13  delivers aggregate to a stacking overland conveyor  15 , which is aligned parallel to the longer axis of the leach pad  11 . Overland conveyor  15  supplies the aggregate to bridge stacker  21 , which is shown retreat stacking a lift  27 . 
     Ahead of bridge stacker  21 , a reclaim bridge conveyor and associated equipment  19 , removes the leached aggregate lift  29  from it&#39;s path. This reclaimed aggregate is mostly unwanted residue. The removed aggregate is supplied to reclaim overland conveyor  17 . Overland conveyor  17  transfers the aggregate to conveyor  23 , which, in turn, supplies it to an extendible overland conveyor  31 . The extendible overland conveyor  31  is shown fully extended to the area  33  furthest away from the material supply. The extendible overland conveyor  31  supplies it&#39;s aggregate to a stacking bridge  35 , which is shown radially stacking the dump aggregate. 
     A normal dump stacking process would start with segment  41 . Then segment  43  would be stacked. Then segment  45 , and segment  47  would be stacked sequentially. After this five segment area is radially stacked, the extendible overland conveyor  31  would be moved to another area, indicated by phantom lines  37  following a path generally indicated by phantom lines  49 , for example. The stacking of each area may take up to a year. A third waste dump stack, area  39 , is also illustrated in phantom lines. A possible path of the extendible overland conveyor  31  for this area is illustrated by phantom lines  53 . 
     FIG. 2 illustrates a typical radial stacker, well known in the prior art, which is used in the system and method of the present invention. Radial stacker  41  has an aggregate receiving end  43  and an aggregate discharge end  45  with a belt conveyor in between. The radial stacker  41  is preferably mounted on a pair of crawler tracks  49 ,  51 . Crawler tracks  49  are located about three quarters along it&#39;s length to the discharge end  45 , below a lift structure  47  that elevates the discharge end  45  of the radial stacker  41  above it&#39;s receiving end  43 . The crawler tracks  49 ,  51  are moveable so that movement of crawler tracks  49  causes the radial stacker to follow a fixed radial arc. Movement of crawler tracks  49  and  51  parallel to the lengthwise axis of radial stacker  41  changes the travel arc for the radial stacker. The rectangular symbol  41  below the three dimensional drawing of the radial stacker shall be used in drawings hereinafter to indicate the radial stacker. 
     FIG. 3 illustrates a self-powered conveyor belt tripper/stacker module  53 , according to the present invention. The tripper module has a receiving hopper  59  at one end, and a discharge chute  57  at it&#39;s other end. A reversible tripper car  61  is movable along the truss structure  55  to remove aggregate from the main belt and discharge the aggregate on either side of the tripper module  53 . The truss structure  55  is mounted on rolling stock, such as wheels or a pair of crawler tracks  65 , for example, at or toward one end and another pair  63  at or toward the other end. The crawler tracks are steerable through about one hundred and eighty degrees. With driveability in a forward and reverse direction the crawler trucks are driveable through three hundred and sixty degrees. The steerable crawler tracks are driven by a power source (not shown). The tripper module  53  is preferably about 300 feet long from its receiving hopper  59  to its discharge chute  57 . The rectangular symbol  53  below the three dimensional drawing is a symbol for the tripper module  53  and will be used to represent the tripper module  53  in subsequent drawings. 
     FIG. 4 illustrates a mobile bridge stacker or mobile stacking conveyor  67 , well known in the prior art, which has a hopper  69  at one end for receiving aggregate and belt conveyor  71  which transports the aggregate to a tripper  73 . The tripper stacks the aggregate in front of the bridge stacker  67 . The entire bridge is made up of multiple sections  68 ,  70  pinned together, which allows for contraction and expansion of the length of the bridge. Each section is supported by crawler tracks  83 ,  81 , and  85 . These crawler tracks allow for radial and lateral movement of bridge stacker  67 . 
     FIG. 5 illustrates a self-powered steerable mobile belt conveyor module  87  according to the present invention. The belt conveyor module  87  has a receiving hopper  89  at one end and a discharge chute  91  at the other end with a conveyor belt in between. The mobile belt conveyor module  87  is built on a truss structure  88 , which is light weight and maneuverable. The truss structure supports a power unit  93  that powers rolling stock, like wheels or a pair of crawler tracks  95  and  97 , for example, with crawler tracks  95  disposed at or toward one end and another pair  97  disposed at or toward the other end. The crawler tracks are steerable through about one hundred eighty degrees and driveable through three hundred and sixty degrees. The mobile belt conveyor module  87  is preferably 250 feet long from its receiving hopper  89  to its discharge chute  91 . The rectangular symbol  87  below the illustration of the mobile belt conveyor module  87  is a symbol for the mobile belt conveyor and will be used to represent the belt conveyor module  87  in subsequent drawings. 
     FIG. 6 represents a retreat stacking system utilizing the system components of the present invention. This figure illustrates the flexibility of the conveyor modules of the present invention. In place of an overland conveyor, for example, a series of mobile conveyor modules  87  are positioned along a center line of a stack pad. The entire assembly is stacking and retreating in the direction of arrows  109  and  103 . 
     As the series of mobile conveyor modules  87  retreat along the corridor  106  in direction  109 , aggregate is being fed to tripper module  53   a , which supplies the aggregate through it&#39;s tripper unit  61 , to another mobile conveyor module  87   b . The tripper unit  61  is a reversible discharge conveyor capable of aggregate discharge to both sides. Tripper module  53   a  is shown loading aggregate into mobile belt conveyor module  87   b  which is displaced laterally  107  from tripper  53   a  by approximately ten to twelve feet. Mobile belt conveyor module  87   b  unloads the aggregate into the receiving hopper of a radial stacker  41   a  which retreat stacks the aggregate  99  in corridor  106 , thereby filling the corridor. 
     At the same time that corridor  106  is being stacked, tripper module  53   a  is supplying aggregate by way of it&#39;s reversible shuttle discharge tripper  61  to another mobile conveyor unit  87   c  which provides it&#39;s aggregate to another tripper conveyor  53   b  which supplies it&#39;s aggregate by way of it&#39;s shuttle discharge conveyor  61  to another mobile belt conveyor module  87   d , which in turn, feeds another radial stacker  41   b . Radial stacker  41   b  stacks aggregate  105  radially in a retreat direction  103  that is lateral to corridor  106 . 
     FIG. 7 shows an isometric view of the topography of an area  112  along with a fixed conveyor belt  101  which is intended to supply all the bulk prepared materials which are to be stacked on the heap stacking area  112 . Fixed conveyor belt  101  will discharge it&#39;s aggregate at discharge point  100 . 
     The topography of the leach stacking area  112  includes two relatively small ridges,  113  and three relatively small valleys  114  which may be naturally occurring or have been prepared by earth moving equipment. For illustration purposes, area  112  will be shown as stacked using two lift cycles. The first lift will be at an elevation that intersects the near side topography along first lift intersection contour  115 . The second lift will be at an elevation that intersects the near side topography along second lift intersection contour  116 . The final crest of the entire heap is to be the final heap crest contour  117 . The final toe is to be the final heap toe contour  118 . 
     The center line axis  119  of the heap area  112  will be the center line axis for the corridors of the two lift cycles according to the preferred embodiment of the present invention. It should be understood, however, that the present invention includes any reasonable number of lifts or lift cycles with the center line axis changing from lift to lift as desired. Center line axis  119  intersects the discharge point  100  of the fixed conveyor belt  101  so that conveyor belt  101  transfers it&#39;s material into the system at discharge point  100  during the entire heap stacking process for area  112 . 
     An area, like area  112  with it&#39;s unique geometry, is suitable for a leach pad since it allows the aggregate to be stacked so that the top of the first lift clears the ridges  113 , thereby allowing the valleys  114  to be used to collect the lixiviant, or leaching liquids containing the recovered metals or minerals, after it has passed through the heap. This choice of a natural topography alleviates the requirement for prior earth work preparation. This site is also suitable for dump stacking aggregate. 
     FIG. 8 illustrates the topography of FIG. 7 with the stacking system components according to the present invention located to begin the stacking process. The view of the area topography is from the far side looking back towards the near side of material supply at discharge point  100  before the first lift cycle begins. The system components are a tripper module  53 , a stacker  41 , and a bridge stacker  67 . All the components are located to begin stacking the extension phase of a lift cycle in an advance stacking mode. The aggregate will begin to be stacked in front of bridge  67  in a tapered fashion outward so that the bridge  67  can travel on top of the newly deposited lift material. In addition, stacker  41  will be building a berm in corridor area  122  during this extension phase of the lift stacking cycle. Stacker  41  may be a radial stacker or a regular conveyor stacker, which can not radial stack, but is capable of stacking a berm (berm stacker). 
     FIG. 9 illustrates the location of the stacking system components with respect to the area topography after stacking has begun. Radial stacker  41  is stacking aggregate in corridor area  122  building a berm to first lift elevation  131 , while at the same time advancing to remain abreast of bridge stacker  67 . Bridge stacker  67  is being supplied with material from tripper module  53 , which is also supplying stacker  41 . Bridge stacker  67  stacks the aggregate in front to it&#39;s lift elevation  131 . Bridge stacker  67  and stacker  41  extend out on top of the newly stacked aggregate at lift level  131 . 
     FIG. 10 illustrates the position of the stacking system components after the advance stacking mode has progressed, as can be seen by the number of mobile belt conveyor modules  87  needed to carry the aggregate from transfer point  100  to tripper module  53 . Tripper module  53  continues to supply the aggregate to bridge stacker  67  and stacker  41 . Stacker  41  continues to deposit material to build the berm  122  to grade level  131 . Bridge stacker  67  continues to deposit aggregate material in front of bridge  67  to stack aggregate in it&#39;s path to lift elevation  131 . Bridge stacker  67  could be operating in both the advance stacking and retreat stacking mode, if desired. This process is described and illustrated hereinafter. 
     The mobile belt conveyor belt modules  87  are moved into position as needed during the extension phase of a lift stock cycle to keep up with the pace of tripper  53 , bridge stacker  67 , and berm stacker  41 . Because the mobile belt conveyors are very mobile and maneuverable, it becomes more or less like adding links to a chain. 
     FIG. 11 illustrates the disposition of stacking system components on the area topography when the first lift cycle extension phase has reached the end of the area furthest away from the material supply point  100 . At this time, the bridge stacker  67  is rotating and translating around the end of area  112  to radially stack the end area and prepare to begin the retraction phase of the first lift cycle. The tripper  53  has been extended full length by using as many of the 250 feet long mobile belt conveyor modules  87  as required to supply aggregate from the discharge point  100  to tripper  53 . Tripper  53 , in turn, supplies the aggregate to stacking bridge  67 , which is now rotating and translating around the area  112  by moving on its track units  85  while continuing to deposit aggregate in front of it. In this way, the far end semi-circle portion of lift  131  is stacked before retraction begins. 
     FIG. 12 indicates the disposition of the stacking system components of the present invention on the area topography during first lift retraction. The number of mobile belt conveyor modules  87  has been reduced, because the distance between the aggregate discharge point  100  and the tripper  53  is being reduced during retraction. Tripper  53  feeds bridge stacker  67 , which continues to deposit aggregate to lift level  131 . Bridge stacker  67  continues to travel on top of the newly stacked lift level  132 . Tripper  53  is retracting on the berm that was stacked during the extension phase. No berm stacker is required during this retraction phase. 
     FIG. 13 illustrates the disposition of the stacking system components of the present invention on the area topography when the first lift retraction cycle is almost completed. The conveyor modules  87  have been reduced considerably because the distance between discharge point  100  and tripper  53  has been reduced to a minimum. Bridge stacker  67  continues to deposit materials in front as it translates over the newly deposited aggregate towards the lift contour  115 . 
     FIG. 14 illustrates the disposition of the stacking system components of the present invention on the area topography when the first lift cycle has been completed. As can be seen, the bridge stacker  67  is rotating and translating on it&#39;s tracks  85  to the starting position behind contour  116  for the start of the second lift cycle. The distance between the bridge stacker  67  and the discharge point  100  is quite small, only requiring one conveyor module  87  and tripper module  53 . 
     FIG. 15 illustrates the disposition of the stacking system components on the area topography when the second lift cycle has begun by tapering the current lift  132  into area  122  from the second lift intersection contour  116 . An alternative approach would be to build a berm for the bridge stacker  67  to ride up on and then proceed to advance and retreat stack the second lift in a manner more specifically illustrated and described hereinafter. Aggregate is discharged at point  100  from fixed conveyor  101  onto mobile belt conveyor module  87  and then to tripper module  53 . Tripper module  53  supplies bridge stacker  67  which stacks the aggregate behind the bridge stacker  67  as it advances in this extension phase, in a typical retreat stacking method. 
     Bridge  67  travels on top of the previously stacked lift  131 , which is at the same grade elevation that newly stacked lift  132  is being deposited on. As bridge  67  continues outward in this extension phase of retreat stacking, a corridor  122  is being formed. 
     FIG. 16 illustrates the disposition of the stacking system components of the present invention on the area topography when the extension phase of the second lift is half way completed. Bridge stacker  67  is stacking material behind it, as it moves forward towards the end of the stack area. Additional mobile belt conveyor modules  87  have been added as needed. The mobile belt conveyors  87  feed tripper module  53  which feeds bridge stacker  67 . The mobile belt conveyors  87  and tripper module  53  are traveling on the previously stacked heap, which is at a level lower than the second lift  132  thereby creating a corridor  122 . 
     FIG. 17 shows the disposition of the stacking system components of the present invention on the area topography when the second lift extension cycle has reached the end of area  112 , which is furthest away from the material supply point  100 . At this point, the maximum number of mobile belt conveyor modules  87  are being utilized. Stacker bridge  67  is, at this time, rotating and translating on it&#39;s tracks  85  in order to complete the far end semicircle portion of lift  132 . Tripper module  53  receives aggregate from the last in the line of mobile belt conveyor modules  87  to feed bridge stacker  67  as it continues to stack material in the retreat mode. 
     FIG. 18 illustrates the stacking system modules of the present invention in the area topography when the second lift is in retraction. The bridge stacker  67  is stacking material on the heap  131  to the second lift level  132 . In retraction, the mobile belt conveyor modules  87  are being removed, as they are no longer needed. The aggregate material is supplied to the tripper module  53 . During retraction, according to the present invention, the tripper module  53  supplies the aggregate to a bridge stacker  67  and to a radial stacker  41 . Bridge stacker  67  continues to retreat and stack the aggregate while the radial stacker  41  starts to stack aggregate into corridor  122 . 
     FIG. 19 illustrates continued retraction of bridge stacker  67  towards the supply point  100 . Radial stacker  41  continues to fill corridor  122  as the second lift retraction cycle continues. The mobile conveyor modules  87  continue to be removed as they are no longer needed. 
     FIG. 20 illustrates the placement of the stacking system components on the area of topography when the second lift cycle is being completed by tapering the current lift level  132  out against the topographic slope contour  116  on the material supply side. At this point, only one mobile belt conveyor module  87  is needed to feed tripper module  53 , which feeds bridge stacker  67 . Bridge stacker  67  is shown as travelling in front of a newly stacked lift  132  and about to pass over the contour  116  on to the topographical slope nearest the material supply point  100 , thereby completing the second lift cycle. 
     The complete process for applying two lifts has been illustrated. It should be kept in mind that more than two lifts are contemplated and are well within the capability of the stacking system components of the present invention. Only two lifts have been illustrated because it was felt this was sufficient to show the smooth and swift stacking sequence obtainable by the present invention. Moreover, although only retreat stacking and advance stacking modes have been shown used separately, the present invention contemplates use of both modes together. 
     Referring now to FIG. 21, a system and method according to the present invention of stacking aggregate on a dump is illustrated. A transfer or reclaim conveyor  139  conveys the aggregate to be dump stacked from an on/off pad  137 , for example, to a transfer point  141  where it is transferred to a conventional extendible conveyor  145 . FIG. 21 illustrates a pair of radially stacked areas  143 , each with a 220 meter radius  163  and  165 , which were radially stacked by a bridge stacker in a manner well known in the art. 
     FIG. 21 shows that after the 440 meter mark, the system and method of the present invention is utilized to finish stacking the dump site. At the end of the 440 meter mark, the end of the extendible conveyor  145  and second section  165 , the aggregate is transferred to a mobile belt conveyor module  87 . The mobile belt conveyor module transfers it&#39;s aggregate to a mobile tripper module  53 . Tripper module  53  supplies the aggregate to a bridge stacker  67  that stacks the aggregate to a first lift level  153  in front, in an advance stacking mode, and also stacks the aggregate behind in a retreat stack stacking mode. The bridge stacker  153  is shown advancing in the direction shown by arrows  161  in the extension phase of the dual lift stacking cycle. 
     The berm  151  on which tripper module  53  travels must be at the same level as the first lift  153 . This berm can be created by utilizing a berm stacker (not shown) or by truck hauled aggregate. 
     FIG. 22 illustrates the end of the extension cycle wherein the system of the present invention is utilizing the maximum number of mobile belt conveyor modules  87  needed to feed tripper module  53 , which feeds bridge stacker  67  that is traversing the end area in an arc to form the curved end of the first dual lift. Bridge stacker  67  continues to stack in the advance and retreat mode depositing aggregate  153  in front of it&#39;s path and aggregate  159  behind it, thereby effectively creating two lifts in one pass. 
     FIG. 23 illustrates the bridge stacker  67  in the extraction phase of the dual lift cycle. Bridge stacker  67  continues to stack material  153  in front and material  159  in back as it travels toward the transfer point  141 . The mobile belt conveyor modules  87  that feed tripper  53  are removed as they are not needed. Tripper module  53 , besides feeding bridge stacker  67 , is now also feeding another mobile belt conveyor module  87  that in turn feeds a radial stacker  41 . Radial stacker  41  lags behind bridge stacker  67  as it fills in newly created corridor  152 . 
     FIG. 24 shows the position of the system components of the present invention at the completion of the stacking cycle of bridge stacker  67 . At this point, although the stack has been completed to lift level  171 , the corridor  152  still needs to be stacked. Tripper module  53  supplies the aggregate to a radial stacker  41  to stack corridor  152  as it is being retracted in direction  173 . 
     Once this first pad has been stacked to lift level  171 , the extendible conveyor  145  is moved from transfer point  141  to a second stack area  175  (FIG. 25) for a second phase of stacking. A bridge tripper  53  located in this second area  175  feeds relocated bridge stacker  67 , which is again operating in both a retreat and advance stacking mode, stacking aggregate  153  in front and aggregate  159  in back at the same time. Extendible conveyor  145  was moved to the position shown from it&#39;s initial position shown in phantom lines  146 . Bridge stacker  67  likewise is moved to it&#39;s new starting position on the second dump stack  175 . The second dump stack  175  is completed in the same manner as described above for the first dump stack  171 . 
     FIG. 26 illustrates the placement of the system components on a third dump stack  185  while constructing a third dual lift. The extendible conveyor  145  has been relocated to the third dump stack area  185 . In order to get to the lift level, equipment ramps  179  were cut into the first and second dump stacks  171  and  175 . Equipment ramp  181  is cut into the third dump stack  185 . Each of these ramps are approximately at 12 degree lift or a 22.25% slope. 
     The mobile belt conveyor modules  87  of the present invention traverse this ramp  181  from the discharge point of the extendible conveyor  145  all the way to the tripper module  53 . Tripper module  53  feeds bridge stacker  67  which stacks in a retreat and advance mode. The corridor being built during the retraction phase shown will be stacked in the same manner as explained above in connection with FIG.  24 . 
     Although only two or three lifts have been shown for purposes of keeping the explanation as short as possible, it should be remembered that the system components of the present invention are capable of stacking many more lifts.