Patent Publication Number: US-7591377-B2

Title: Method and apparatus for a vibrating screen aggregate separator

Description:
This application claims the benefit of U.S. Provisional Application No. 60/757,606, filed Jan. 10, 2006, the contents of which are incorporated herein by reference in their entirety. 

   FIELD OF THE INVENTION 
   The present invention generally relates to aggregate separators, and more particularly to a mobile, vibrating screen apparatus that is used to separate granular materials. 
   BACKGROUND 
   Since excavation of materials from the earth&#39;s surface, or subjacent to the earth&#39;s surface, has been occurring, the need to refine the excavated material has existed. In particular, the excavated material is often comprised of various compositions, such as rock, sand, pebbles, mineral deposits, and other contaminants or otherwise undesirable compositions. In such instances, the desired material, e.g., sand and pebbles of reduced diameter, are often required to be separated from larger diameter contaminants that may be contained within the excavated material. 
   Depending upon the application, separation of the larger diameter contaminants from the desired material may be accomplished through the use of a number of various aggregate separation devices. Vibratory feeders, for example, utilize conveyor belts that are configured to: accept raw material input at one end of the conveyor belt; transport the raw material to the other end of the conveyor belt; vibrate the conveyor belt during transport to mechanically expel unwanted material; and deposit the refined material at the opposite end of the conveyor belt. Other conveyor based feeders may utilize electromagnetic means to separate ferrous materials from non-ferrous materials. 
   Due to the sheer size and weight of these prior art aggregate separators, however, transportability becomes an almost prohibitive constraint to their use at job sites whose locations are constantly changing. Fixed location quarries, on the other hand, may utilize these prior art aggregate separators effectively, since once the prior art aggregate separators are installed at the quarry, transportability is no longer an issue. 
   Other job sites requiring excavation and back filling operations, such as construction job sites, however, pose transportability issues in regard to prior art aggregate separators. For example, the size and weight of conveyor based aggregate separators nearly preclude their transport via towable trailers, especially to construction sites having limited access. In addition, should the conveyor based aggregate separators find their way to a particular construction job site, their mere presence may hinder other construction activities that may be occurring at the job site, simply due to the amount of area required to operate the conveyor based aggregate separators. 
   Efforts continue, therefore, to improve the methods and apparatus that may be used for aggregate separation. In particular, advancements are desired to develop aggregate separators that are more conducive to transportability. In addition, once at the job site, such a transportable aggregate separation device must occupy as little space as possible, so as to avoid disruption of other activities that may be occurring. 
   SUMMARY 
   To overcome limitations in the prior art, and to overcome other limitations that will become apparent upon reading and understanding the present specification, various embodiments of the present invention disclose an apparatus and method of using a highly mobile, vibrating screen aggregate separator to separate finer grained materials from more coarsely grained materials. 
   In accordance with one embodiment of the invention, an aggregate separation device comprises a container, a suspension system that is coupled to the container, and a screen that is coupled to the suspension system. The screen is configured with a plurality of perforations having a first diameter. The aggregate separation device further comprises a hollow shaft that is coupled to the screen, an unbalanced rod displaced within the hollow shaft, a mechanical energy source that is coupled to the unbalanced rod and is adapted to rotate the unbalanced rod to transfer vibrational energy to the screen via the hollow shaft. The aggregate separation device further comprises a support bearing that is coupled along a length of the unbalanced rod to prevent excessive deflection of the unbalanced rod during rotation. 
   In accordance with another embodiment of the invention, a method of separating desired material from an aggregate material comprises placing a quantity of aggregate material onto a screen, the screen being configured with a plurality of perforations having a first diameter. The method further comprising displacing an unbalanced rod within a hollow shaft, rotating the unbalanced rod within the hollow shaft to transfer vibrational energy to the screen, supporting the unbalanced rod at a midpoint along a length of the unbalanced rod to eliminate excessive deflections of the unbalanced rod during rotation and filtering desired material from the aggregate material through the screen in response to the vibrational energy transfer. The desired material being composed of granules having a diameter less than the first diameter. 
   In accordance with another embodiment of the invention, an aggregate separation device comprises a container having first and second openings, a suspension system that is coupled to the container, a screen that is coupled to the suspension system and displaced over the first opening. The screen is configured with a plurality of perforations having a first diameter. The aggregate separation device further comprises a hollow shaft that is coupled to the screen, the hollow shaft including an unbalanced rod displaced within the hollow shaft. The aggregate separation device further comprises a mechanical energy source that is coupled to the unbalanced rod and is adapted to rotate the unbalanced rod to vibrate the screen. The aggregate material that is placed on the screen is filtered into granules having a diameter less than the first diameter by the vibrating screen and the granules are accessible within the container via the second opening. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various aspects and advantages of the invention will become apparent upon review of the following detailed description and upon reference to the drawings in which: 
       FIG. 1A  illustrates a front view of an exemplary vibrating screen aggregate separator; 
       FIG. 1B  illustrates the front view of an alternate embodiment of the vibrating screen aggregate separator of  FIG. 1A ; 
       FIG. 1C  illustrates an exploded view of a stop mechanism used by the vibrating screen aggregate separators of  FIGS. 1A and 1B ; 
       FIG. 2A  illustrates a rear view of the vibrating screen aggregate separator of  FIGS. 1A and 1B ; 
       FIG. 2B  illustrates a rear view of an alternate vibrating screen aggregate separator; 
       FIG. 3A  illustrates an expanded view of the vibrating screen aggregate separator of  FIG. 1A ; 
       FIG. 3B  illustrates an alternate expanded view of the vibrating screen aggregate separator of  FIG. 1B ; 
       FIG. 4A  illustrates exemplary details of a container of the vibrating screen aggregate separator of  FIGS. 1A and 1B ; 
       FIG. 4B  illustrates alternate details of an exemplary container of the vibrating screen aggregate separator of  FIGS. 1A and 1B ; 
       FIG. 5  illustrates an exemplary suspension system of the vibrating screen aggregate separator of  FIGS. 1A and 1B ; 
       FIG. 6  illustrates an exemplary diagram of the screen/support structure composite assembly of the vibrating screen aggregate separator of  FIGS. 1A and 1B ; 
       FIG. 7A  illustrates exemplary details of a support structure of the vibrating screen aggregate separator of  FIG. 1A ; 
       FIG. 7B  illustrates alternate details of a support structure of the vibrating screen aggregate separator of  FIG. 1A ; 
       FIG. 7C  illustrates exemplary details of a support structure of the vibrating screen aggregate separator of  FIG. 1B ; 
       FIG. 7D  illustrates alternate details of a support structure of the vibrating screen aggregate separator of  FIG. 1B ; 
       FIG. 8  illustrates a transportable configuration of the vibrating screen aggregate separator of  FIG. 1 ; and 
       FIG. 9  illustrates a flow diagram of a method of operating a vibrating screen aggregate separator. 
   

   DETAILED DESCRIPTION 
   Generally, the various embodiments of the present invention are applied to a vibrating screen aggregate separation device that may be used to separate granular material. In particular, a mesh design associated with the screen, such as a sieve, contains perforations to allow smaller diameter material, i.e., the desired material, to pass through into a container that is situated below the screen. The screen may be angled so that once the pre-screened material is placed on top of the screen, the larger diameter material, i.e., the undesired material, may simply roll off of the screen to be safely separated away from the desired material that is stored within the container. 
   Guiding panels may be attached to the container and situated above the screen, to allow pre-screened material to be placed on the screen with a minimum of spillage. Such may be the case, for example, when the bucket width of a front loader, bucket loader, or other material moving device, is wider than the vibrating screen. In such instances, once the bucket is maneuvered to drop material onto the vibrating screen, material from each end of the bucket may be collected by each guiding panel and directed to the vibrating screen for subsequent separation. 
   A suspension system may be affixed between the container and the vibrating screen to allow a range of motion that is conducive to vibration of the screen, while at the same time, is supportive of the weight of the pre-screened material. That is to say, in other words, that the screen is maintained at a separation distance from the container, so as to allow full scale deflection of the screen during all vibration cycles while simultaneously preventing contact between the screen and the container. 
   Thus, so long as the weight of the pre-screened material is maintained within the weight constraints of the suspension system, full scale deflections may be imparted to the screen in an oscillatory fashion, so as to cause a vibrating movement of the screen. During screen vibration, aggregate is separated into one of two material types: 1) oversized material that rolls off the screen with a trajectory defined by the pitch orientation of the screen to form a pile of undesired material; or 2) appropriately sized material that passes through the mesh of the screen into the container to form a pile of desired material. The maximum size of each grain of the desired material may be selected by appropriately adjusting the diameter of the mesh perforations of the screen to be equal to the maximum grain size that is required in the desired material. 
   Oscillatory deflections may be imparted to the screen via rotation of an unbalanced rod along its longitudinal axis within a hollow shaft that may be coupled to the screen. An unbalance is formed in the rod by creating a mass at each end of the rod that is greater than the rod&#39;s mass at its center. As the rod is rotated along its longitudinal axis, the angular momentum at each end of the rod is greater than the angular momentum at the center of the rod due to the increased mass at each end of the unbalanced rod. Thus, the moment of inertia generated at each end of the rod is greater than the moment of inertia at the rod&#39;s center. The difference in moments of inertia imparts an oscillation to the screen, whose fundamental frequency is inversely proportional to the amount of time required to rotate the unbalanced rod through a 360 degree cycle. 
   The unbalanced rod may be housed within a hollow shaft, the hollow shaft being rigidly coupled to the screen and associated supporting structures. At each end of the hollow shaft, supporting structures, such as pillow block bearings, may be attached. The unbalanced rod may then be secured to each pillow block bearing to provide load support during the unbalanced rod&#39;s rotation along its longitudinal axis. 
   In order to add further stability to the unbalanced rod during rotation, a third supporting structure may be added. In particular, while the unbalanced rod is secured at each end by, for example, pillow block bearings, an additional pillow block bearing may be added at, or near, the center point of the unbalanced rod. As such, positioning of the unbalanced rod through all rotation cycles may be controlled so as to avoid excessive deflections of the unbalanced rod that are orthogonal to its longitudinal axis. 
   Such deflections may be caused, for example, by the elasticity of the material used for the unbalanced rod, whereby excessive forces imposed on the unbalanced rod cause it to bend, or strain, under stress. In other embodiments, the necessity of a center-mounted support structure for the unbalanced rod may be obviated by increasing the rigidity of the unbalanced rod, thereby decreasing its elasticity. Such increases in rigidity may be accomplished, for example, through selection of more rigid materials, or conversely, through a design of the unbalanced rod that is resistant to stress induced deformation. 
   The unbalanced rod&#39;s rotation may be effected by applying a rotational force at either end of the rod. In one embodiment, a pulley, or gear, may be attached to one end of the rod, which may then be coupled to a mechanical energy source, such as an electrical motor or combustion engine. The motor or engine, having its own rotating shaft and pulley, or gear, may then impart rotational energy to the unbalanced rod via a belt or chain. In particular, the pulley that is attached to the motor may be non-rigidly coupled, via a belt or chain, to the pulley that is attached to the unbalanced rod. As such, the motor&#39;s shaft may rotate substantially vibration free, while at the same time imparting rotational energy to the unbalanced rod, which in turn imparts oscillatory deflections to the unbalanced rod that are orthogonal to its longitudinal axis of rotation. 
   As the unbalanced rod oscillates, vibrational energy is transferred to the screen, whereby variations in the tension of the belt or chain may also occur. However, due to the non-rigidity of the belt or chain that couples each pulley, oscillatory deflections of the unbalanced rod do not cause damage to the motor, since any potentially damaging deflections are largely absorbed by the interaction of the belt or chain with each pulley. 
   Turning to  FIG. 1A , a front view of exemplary vibrating screen aggregate separator  100  is illustrated. As can be seen, support structure  104  may be coupled to screen  106  via various support members of support structure  104 . Each support member may include vertical support members  114  and/or other support members (not shown) to provide support at other angles with respect to screen  106 . 
   Guiding panels  108  may be attached to container  102  and situated above screen  106  as illustrated, to allow pre-screened material to be placed onto screen  106  with a minimum of spillage. Such may be the case, for example, if the bucket width of a front loader, bucket loader, or other material moving device, is wider than the width of screen  106 . In such instances, once the bucket is maneuvered to drop material onto screen  106 , material from each end of the bucket may be collected by each guiding panel  108  and directed to screen  106  for subsequent separation. 
   In particular, it can be seen that each guiding panel  108  extends outward from two sides of container  102 . Each guiding panel  108  is additionally angled downward, toward screen  106  and support structure  104 , such that once pre-screened material is deposited onto guiding panels  108 , the pre-screened material may slide onto screen  106  via gravitational and/or vibrational forces that are active during operation of vibrating screen aggregate separator  100 . 
   As discussed in more detail below, suspension system  112 , may be coupled between container  102  and screen  106  to allow a range of motion that is conducive to vibration of screen  106 , while at the same time, is supportive of the weight of the pre-screened material that is deposited onto screen  106 . That is to say, in other words, that screen  106  is maintained at a separation distance  118  from container  102 , so as to allow full scale deflection of screen  106  and supporting structure  104  during all vibration cycles, while simultaneously preventing contact between screen  106 /supporting structure  104  and container  102 . 
   Thus, so long as the weight of the pre-screened material is maintained within the design constraints of suspension system  112 , full scale deflections may be imparted to screen  106  in an oscillatory fashion, so as to cause a vibrating movement of screen  106 . As discussed in more detail below, for example, suspension system  112  may include a plurality of coiled springs having a plurality of spring constants k 1 , k 2 , . . . , kn, and associated range of physical dimensions. Each of the plurality of springs may then interact with one another to produce a variable compression force that is adaptive to the position of screen  106  and support structure  104  relative to container  102 . 
   For example, once the initial load of pre-screened material is deposited onto screen  106  and support structure  104 , the amount of compression force that is exerted by suspension system  112  is maximized by the mechanical engagement of individual springs within suspension system  112  that have higher spring constants. As the pre-screened material begins to either drop into container  102 , or is rejected by screen  106 , the amount of compression force that is exerted by suspension system  112  reduces due to the decreasing weight of the pre-screened material. As such, during the course of aggregate separation of a single load of material, distance  118  is maintained within a range of distance, such that support structure  104  and screen  106  is precluded from making contact with container  102 . 
   During the vibrating movement of screen  106 , which is induced by shaft  116 , the oversized material either rolls off screen  106  with a trajectory defined by the pitch orientation of screen  106 , or the desired material passes through the mesh of screen  106  into container  102 . The maximum size of each grain of the desired material may be selected by appropriately adjusting the diameter of mesh perforations  120  of screen  106  to be equal to the maximum grain size that is required in the desired material. 
   Mobility of vibrating screen aggregate separator  100  is exemplified in at least 2 respects. First, a conveyor system is not required, which allows vibrating screen aggregate separator  100  to be easily transported to a job site via virtually any truck and/or towable trailer. Second, once at the job site, optional casters  110  allow maneuvering of vibrating screen aggregate separator  100  to a location within the job site that is unobtrusive to the other activities that may be occurring at the job site. 
   Turning to  FIG. 1B , an alternate embodiment of vibrating screen aggregate separator  100  is exemplified, whereby support structure  152  is incorporated. In particular, support structure  152  may exist at, or about, the center point along the length of shaft  116 , whereby shaft  116  may be rigidly coupled to each end of support structure  152 . As discussed in more detail below, support structure  152  implements additional stability for shaft  116 , as well as its contents, during vibration of screen  106 . 
   Turning to  FIG. 1C , an exploded detail of a stop mechanism for the vibrating aggregate separators of  FIGS. 1A and 1B  is exemplified. Due to the non-rigidity of the coupling between screen  106  and container  102 , under certain conditions, screen  106  may tend to pitch upward causing suspension system  112  to hyperextend, or in an extreme case, cause screen  106  to separate from container  102 . Such a hyperextension may be caused, for example, by an uneven load of aggregate placed onto screen  106 , or simply during the initiation or cessation of the vibration of screen  106 . 
   In such instances, one or more rods  154  may be inserted through one or more corners of support structure  104  and corresponding corners of container  102  as illustrated. Retainer nuts  158 , or other coupling means, may be secured at each end of rod  154  so as to maintain spring  156  at a positive compression force. In operation, any upward movement of screen  106  and support structure  104  may be opposed by the compression force of spring  156 , such that any hyperextension of spring  112  is reduced by the compression force of spring  156  and eventual dead stop by retainer nuts  158 . 
   Turning to  FIG. 2A , the back side of vibrating screen aggregate separator  200  is exemplified, whereby opening  202  is provided within container  102 . In particular, as the screened material falls into container  102  during operation, it collects into a pile of desired material within container  102  that is accessible via opening  202 . As such, the bucket of a front loader, bucket loader, or other material moving device, having a bucket width that is narrower than opening  202  may be easily inserted into opening  202 . 
   Thus, the pile of desired material may be extracted from container  202  by inserting the bucket into opening  202 , scooping the desired material into the bucket, and transporting the desired material to various locations within the construction site that are in need of screened aggregate. Such locations may include plumbing, sewage, and utility trenches, as well as any other excavations, that are in need of screened backfill. 
   As discussed in more detail below, vibrating screen aggregate separator  200  may include a mechanical energy source, such as an electrical motor or combustion engine  204 . Motor  204  may transfer rotational energy to pulley  208  via a non-rigid energy transfer mechanism, such as belt or chain  206 . Pulley  208  may in turn be coupled to an unbalanced rod (not shown), which is rotated by the rotational energy transferred to pulley  208 , which in turn causes vibration during operation of vibrating screen aggregate separator  200 . 
   Turning to  FIG. 2B , the back side of an alternate vibrating screen aggregate separator  250  is exemplified, whereby an alternately shaped opening  254  is provided within container  252 . In particular, opening  254  is squared off at the corners in order to provide the largest opening possible to facilitate retrieval of the desired material from container  252 . In addition, the floor of container  252  is removed to further facilitate retrieval of the desired material from container  252  by providing maximum vertical clearance of opening  254 . Further, casters have been removed from vibrating screen aggregate separator  250 , whereby an alternate means of mobility is implemented as discussed in more detail below. 
   Turning to  FIG. 3A , an expanded view of vibrating screen aggregate separator  300  is exemplified. Screen  106  and support structure  104  may be coupled together in a rigid manner, e.g., via welded or bolted connections. The screen  106 /support structure  104  composite assembly may, or may not, be coupled to suspension system  112  in a rigid manner. In such an instance, the screen  106 /support structure  104  composite assembly “floats” above container  102 , whereby the distance between the screen  106 /support structure  104  composite assembly and container  102  is maintained within a distance range. The distance range is conducive to allow a full load of pre-screened aggregate to be placed on top of the screen  106 /support structure  104  composite assembly, while at the same time facilitating screening of the aggregate material via oscillatory deflections that are applied to the screen  106 /support structure  104  composite assembly. 
   Oscillatory deflections may be imparted to the screen  106 /support structure  104  composite assembly via rotation of unbalanced rod  306  along its longitudinal axis. In particular, the rod&#39;s mass at each end of the rod is made to be greater than the rod&#39;s mass at its center, by the addition of weight offsets  308 . In one embodiment, weight offsets  308  may be comprised of the same material as unbalanced rod  306 . As such, shorter sections of rod material may be welded, clamped, bolted, or otherwise coupled to unbalanced rod  306  to provide weight offsets  308 . 
   As unbalanced rod  306  is rotated along its longitudinal axis, the angular momentum at each end of unbalanced rod  306  is greater than the angular momentum at the center of unbalanced rod  306 . Thus, the moment of inertia generated at each end of unbalanced rod  306  is greater than the moment of inertia at the center of unbalanced rod  306 . The difference in moments of inertia imparts a vibrational oscillation to the screen  106 /support structure  104  composite assembly, whose fundamental frequency is inversely proportional to the amount of time required to rotate unbalanced rod  306  through a 360 degree cycle. 
   In order to facilitate the transfer of vibrational energy, unbalanced rod  306  may be displaced within hollow shaft  302 , where hollow shaft  302  may be coupled to the screen  106 /support structure  104  composite assembly. At each end of hollow shaft  302 , supporting structures, such as pillow block bearings  304 , may be attached. Unbalanced rod  306  may then be secured to each pillow block bearing  304  to provide load support during the rotation of unbalanced rod  306  within hollow shaft  302 . 
   The rotation of unbalanced rod  306  may be effected by applying a rotational force at either end of unbalanced rod  306 . In one embodiment, pulley  208  may be attached to one end of unbalanced rod  306 , which may then be coupled to a mechanical energy source, such as an electrical motor, or combustion engine  204 . Motor  204 , having its own rotating shaft and pulley  310 , may then impart rotational energy to unbalanced rod  306  via belt or chain  206 . In particular, pulley  310  may be non-rigidly coupled, via belt or chain  206 , to pulley  208  in order to allow mechanical energy to be transferred from motor  204  to unbalanced rod  306 . 
   As such, the shaft of motor  204  may rotate substantially vibration free, while at the same time imparting rotational energy to unbalanced rod  306 , which in turn causes oscillatory deflections of unbalanced rod  306  that are orthogonal to its longitudinal axis of rotation. As unbalanced rod  306  oscillates, variations in the tension of belt or chain  206  may also occur. However, due to the non-rigidity of belt or chain  206  that couples each pulley, oscillatory deflections of unbalanced rod  306  do not cause damage to the motor, since any potentially damaging deflections are substantially absorbed by the interaction of belt or chain  306  with pulleys  208  and  310 . 
   Oscillatory deflections of unbalanced rod  306  further cause vibrational energy to be transferred to the screen  106 /support structure  104  composite assembly via hollow shaft  302  and the supporting structures of hollow shaft  302 . As vibrational energy is transferred to the screen  106 /support structure  104  composite assembly, pre-screened aggregate previously placed onto screen  106  is caused to either fall into container  102  as desired material, or to slide off of screen  106  as undesired material. The desired material may then be collected via openings  202  and  254  as discussed above in relation to  FIGS. 2A and 2B . 
   Turning to  FIG. 3B , an alternate embodiment of vibrating screen aggregate separator  300  is exemplified, whereby in order to add further stability to unbalanced rod  306  during rotation, supporting structure  352  may be added. In particular, while the unbalanced rod is secured at each end by, for example, pillow block bearings  304 , an additional pillow block bearing  352  may be added at, or near, the center point of unbalanced rod  306 . As such, positioning of unbalanced rod  306  through all rotation cycles may be controlled so as to avoid excessive deflections of unbalanced rod  306  that are orthogonal to its longitudinal axis. Such deflections may be caused, for example, by the elasticity of the material used for the unbalanced rod, whereby excessive forces imposed on the unbalanced rod cause it to bend, or strain, under stress. 
   Support structure  152  may also be added at, or near, the mid-point of hollow shaft  302  (not shown in  FIG. 3B ). In such an instance, hollow shaft  302  may be rigidly coupled to either side of support structure  152  without passing through the interior of support structure  152  as discussed above in relation to  FIG. 1B . Unbalanced rod  306  rotates within the interior of support structure  152  while being further supported by pillow block bearing  352  during rotation. As such, excessive deflections of unbalanced rod  306  are substantially eliminated by pillow block bearing  352  to prevent undue stress or strain on unbalanced rod  306  during rotation. 
   In other embodiments, the necessity of a center-mounted support structure for unbalanced rod  306  may be obviated by increasing the rigidity of unbalanced rod  306 , thereby decreasing its elasticity. Such increases in rigidity may be accomplished, for example, through selection of more rigid materials, or conversely, through a design of the unbalanced rod that is resistant to stress induced deformation. For example, ribs may be disposed along the longitudinal axis of unbalanced rod  306  in order to provide additional stiffness. 
   Turning to  FIG. 4A , other details of container  102  are exemplified. In particular, as discussed above, container  102  may provide a downward slope from one end of container  102  to the other, whereby top edge  406  is higher than bottom edge  410  with respect to vertical axis  412 . Such a slope allows aggregate material to more easily roll/slide off of vibrating screen  106  of  FIGS. 1A-1C  during the aggregate separation operation. 
   In one embodiment, container  102  is comprised of four walls that extend along vertical axis  412 , where the four walls provide top edges  404 - 410 . Thus, top edges  404 - 410  combine to form the structural support for suspension system  112 , as well as the support for the screen  106 /support structure  104  composite assembly of  FIGS. 1A-1C . 
   Ingress of the desired material into container  102  during aggregate separation is facilitated by opening  402 , which provides the outlet that is required by the screen  106 /support structure  104  composite assembly of  FIGS. 1A-1C . In particular, opening  402  allows screened material to fall into container  102  during aggregate separation. Egress of the desired material is further facilitated by opening  416  as exemplified in  FIG. 4B . In one embodiment, for example, opening  416  may exist at back side  414  of container  102 , whereby back side  414  also forms top edge  406 . Other embodiments may instead provide egress of the desired material either from an opening that exists at the front side of container  102 , or from openings that exist at the left and/or right side of container  102 . 
   Turning to  FIG. 5 , suspension system  112 , as discussed above in relation to  FIGS. 1A-1C , is exemplified in greater detail. Suspension system  112  may be comprised of a plurality of coiled spring assemblies  502  having a plurality of spring constants k 1 , k 2 , . . . , kn, and associated range of physical dimensions. As illustrated, springs  506  are shown to have a larger diameter than springs  504 , such that springs  504  may have a larger spring constant as compared to the spring constant of springs  506 . 
   Any number of spring assemblies may be attached to top edges  404 - 410 , whereby in one embodiment, two spring assemblies  502  may be coupled to top edge  406  and two spring assemblies  502  may be coupled to bottom edge  410 . Spring assemblies  502  may also be coupled to top edges  404  and  408  as required. While spring assemblies  502  are shown to be comprised of inner spring  504  and outer spring  506 , other configurations (not shown) may be provided such that springs  504  and  506  may exist independently of one another. 
   In operation, spring assemblies  502  are engaged to maintain the vibrating screen and associated support structure (not shown) at a minimum separation distance from container  102 , so as to allow full scale deflection of the vibrating screen and associated support structure during all vibration cycles. For example, once the initial load of pre-screened material is deposited onto the vibrating screen and associated support structure, the amount of compression force exerted by suspension system  112  is maximized, such that springs  504  and  506  combine to support the weight of the pre-screened material, as well as the vibrating screen and associated support structure. 
   As the pre-screened material begins to either drop into container  102 , or is rejected by the vibrating screen, the amount of compression force that is exerted by suspension system  112  reduces due to the decreasing weight of the pre-screened material. In particular, springs  504  may be allowed to reach their uncompressed height once the pre-screened material has reached a threshold weight, whereas springs  506  remain compressed to the extent necessary to support the weight of the remaining pre-screened material, as well as the vibrating screen and associated support structure. As such, during the course of aggregate separation of a single load of material, a distance is maintained within a range of distance, such that the vibrating screen and associated support structure are precluded from making contact with container  102  during each vibration cycle. 
   Turning to  FIG. 6 , an exemplary diagram of the screen  106 /support structure  104  composite assembly of  FIGS. 1A-1C  is illustrated. Support structure  104  may assume virtually any shape, but is illustrated as a substantially rectangular structure. Longitudinal beams  604  are sized such that they coincide with top edges  406  and  410  of container  102  as illustrated in  FIGS. 4 and 5 . Similarly, beams  606  are configured to be substantially perpendicular to beams  604  and are sized such that they coincide with side edges  404  and  408  of container  102 . Other beams  608  may be added to support structure  104  at varying angles with respect to beams  604  and  606  as may be necessary for added support. 
   Screen  106  and support structure  104  may be coupled together in a rigid manner, e.g., via welded or bolted connections, to form a composite assembly. The composite assembly may then “float” above container  102  of  FIGS. 1A-1C , whereby the distance between the screen  106 /support structure  104  composite assembly and container  102  is maintained within a distance range by suspension system  112  as discussed above in relation to  FIGS. 1A-1C ,  3 , and  5 . 
   The dimensions of mesh perforations  612  and  614  of screen  106  may be selected to be equal to the maximum grain size that is allowed to be collected as desired material within container  102 . In particular, any particle of pre-screened aggregate having dimensions smaller than those defined by mesh perforations  612  and  614  are allowed passage into container  102  during aggregate separation. Any particle of pre-screened aggregate having dimensions larger than those defined by mesh perforations  612  and  614 , on the other hand, are disallowed passage into container  102  and are thus required to roll/slide off of screen  106  to form the separated undesired material pile located outside of container  102 . 
   Turning to  FIGS. 7A through 7D , alternate embodiments of support structure  104  are illustrated. In  FIG. 7A , for example, support beams  606  and  608  are bored at approximately their center points to allow insertion of hollow shaft  302 . Once inserted, hollow shaft  302  may be clamped, welded, bolted, or otherwise rigidly coupled to beams  606  and  608 . At each end of hollow shaft  302 , supporting structures, such as pillow block bearings  304 , may be attached as discussed above in relation to  FIG. 3A . The unbalanced rod (not shown) may then be secured to each pillow block bearing  304  at coupling positions  702  in order to provide load support during the rotation of the unbalanced rod within hollow shaft  302  during aggregate separation. 
   In  FIG. 7C , for example, support beams  606  and  608  are bored at approximately their center points to allow insertion of hollow shaft  302 . Support structure  152  may also be displaced between support beams  608 . Once inserted, hollow shaft  302  may be clamped, welded, bolted, or otherwise rigidly coupled to beams  606  and  608  and to each side of support structure  152  as illustrated. At each end of hollow shaft  302 , supporting structures, such as pillow block bearings  304 , may be attached as discussed above in relation to  FIG. 3B . In addition, pillow block bearing  352  (not shown) may be mounted to the interior of support structure  152  as discussed above in relation to  FIG. 3B . The unbalanced rod (not shown) may then be secured to each pillow block bearing  304  at coupling positions  702 , as well as to pillow block bearing  352 , in order to provide load support during the rotation of the unbalanced rod within hollow shaft  302  during aggregate separation. 
   Turning to  FIG. 7B , support beams  606  and  608  are not bored, but are instead left intact. As such, hollow shaft  302  may be coupled to the underside of beams  606  and  608  via one or more of a clamped, welded, bolted, or other rigid coupling means. At each end of hollow shaft  302 , supporting structures, such as pillow block bearings  304 , may be attached as discussed above in relation to  FIG. 3A . The unbalanced rod (not shown) may then be secured to each pillow block bearing  304  at coupling positions  702  in order to provide load support during the rotation of the unbalanced rod within hollow shaft  302  during aggregate separation. 
   Turning to  FIG. 7D , support beams  606  and  608  are not bored, but are instead left intact. As such, hollow shaft  302  may be coupled to the underside of beams  606  and  608  and to each side of support structure  152  via one or more of a clamped, welded, bolted, or other rigid coupling means. At each end of hollow shaft  302 , supporting structures, such as pillow block bearings  304 , may be attached as discussed above in relation to  FIG. 3B . Pillow block bearing  352  (not shown) may also be displaced within the interior of support structure  152 . The unbalanced rod may then be secured to each pillow block bearing  304  at coupling positions  702 , as well as to pillow block bearing  352  (not shown), in order to provide load support during the rotation of the unbalanced rod within hollow shaft  302  during aggregate separation. 
   As discussed above, aggregate separation can be useful anytime materials are excavated and then reused. In one application, vibrating screen aggregate separator  808  of  FIG. 8  may be transported to a construction site via truck  802  and/or towable trailer  806 . In the illustrated embodiment, vibrating screen aggregate separator  808  is not configured with casters and is instead located to a position within the construction site through the use of tractor  804 . 
   In such an instance, vibrating screen aggregate separator  808  may be lifted off of trailer  806  by inserting the bucket of tractor  804  into openings  202 ,  254 , and  416  as illustrated in  FIGS. 2A ,  2 B, and  4 B, respectively. In particular, once the bucket of tractor  804  is inserted into opening  202 , as illustrated in  FIG. 8 , vibrating screen aggregate separator  808  may be lifted off of trailer  806 . Vibrating screen aggregate separator  808  may then be located anywhere within the construction site by: backing tractor  804  off of trailer  806 ; relocating vibrating screen aggregate separator  808  to the desired location; and lowering the bucket of tractor  804  at the desired location. 
   Turning to  FIG. 9 , a method of operating vibrating screen aggregate separator  808  is exemplified. It is noted that steps  902  and  904  may be interchanged with one another, since rotation of unbalanced rod  306  to cause vibration of screen  106  may be commenced prior to placing a load of aggregate material onto screen  106 . Once at the desired location, motor  204  of  FIGS. 2A ,  2 B, and  3 A may be started, which causes rotation of unbalanced rod  306  of  FIGS. 3A-3B  as in step  904 . Rotation of unbalanced rod  306  then transfers vibrational energy to screen  106  and supporting structure  104  as discussed above. Any aggregate material placed onto screen  106 , via step  902 , is then filtered into desired material as in step  906 , which falls into container  102  of  FIGS. 1A-1C ,  2 A,  2 B,  3 A,  4 A- 4 B, and  5  for collection as in step  908 . Any undesired material rolls or slides off of screen  106  to be safely separated from the desired material within container  102 . 
   In operation, therefore, tractor  804  may collect all material that has been excavated from plumbing, sewage, and utility trenches, as well as any other excavations that may have been necessary at the construction site. The collected material may then be transported to vibrating screen aggregate separator  808  via tractor  804  and deposited onto vibrating screen  106 , whereby any spillage is minimized by guiding panels  108 . Those trenches requiring backfill of a finer composition may then be filled with the desired material that is generated by vibrating screen aggregate separator  808 . In particular, tractor  806  may collect the desired material from within container  102 , via openings  202 ,  254 , and  416  as in step  910 , and may relocate the desired material to those trenches requiring a finer composition backfill. 
   Other aspects and embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended, therefore, that the specification and illustrated embodiments be considered as examples only, with a true scope and spirit of the invention being indicated by the following claims.