Abstract:
An apparatus for separating a mixed particulate material into particles of at least two different specific gravities or ranges of specific gravity, wherein the apparatus comprises an air compressor for providing compressed air into the discharge tube, which, through the venturi effect, creates a vacuum in a connecting hose. The connecting hose is connected to the top of a separation chamber wherein the mixed particulate material, which is vacuumed in by a vacuum hose, is separated and the particles fall into a hopper, while the lighter material is discharged from the discharge tube by virtue of the vacuum created by the flow of compressed air. A conveyor can be used to collect either or both of the lower and higher specific gravity materials, and bring them to other locations. A number of different sensors can be added to the automatic unloader valve to determine when a pre-determined amount of material has been collected. The entire operation of the apparatus can be controlled by a computer, which can also be connected through a network to other computers whereby the apparatus for separating materials can be operated remotely.

Description:
PRIORITY 
     The present application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No. 60/400,043, filed Aug. 2, 2002, the entire content of which is expressly incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention is directed generally to separation apparatus, and is particularly concerned with a mobile apparatus for separating mixed particulate material into particles of different sizes and/or different specific gravities. The invention also relates to method for separating mixed particulate materials into particles of different sizes and/or specific gravities and to methods for operating a mobile mixed particulate material separation apparatus in accordance with the characteristics of the material being separated. 
     BACKGROUND OF THE INVENTION 
     There are many situations in which it is necessary to separate a mixed granular or particulate material into granules or particles of different sizes, specific gravities or both. One example, in connection with which the present invention finds particular utility, is the remediation of indoor or outdoor firearm training facilities which have become saturated with lead from used bullets. In this saturated state, it can be unsafe to continue use of the firearm training facilities. In order to restore these sites to an unsaturated, usable condition, the lead bullets must be removed from the backstop material with which they are mixed, and then the backstop material may then be re-used, recycled or discarded. Different types of backstop material (e.g., sand, or granulated rubber), make it difficult to use any one type of remediation system at different facilities. Mechanical screening can, at least to some degree, be used to separate the mixture of backstop material and bullets into its component parts; however, since mechanical screening relies on size differences between the granules or particles to be separated, it is not capable of separating bullets and backstop material which are of the same or similar size. 
     Separation of used bullets from backdrop material allows for recycling of the lead, which requires a certain level of purity in the product to be recycled. By separating the lead bullets from similarly sized backstop material, the backstop material can be returned to the site for repeated usage. The lead bullets can then be removed from the site in a relatively pure form for recycling and reuse. 
     Air separation (also known as dry separation) provides a method for separating mixed granular or particulate materials into their component parts by relying on differences in the specific gravity (rather than size) of the granules or particles to be separated. The theory of air separation is well understood by those skilled in art. Briefly, air separation is carried out by allowing the mixed granular or particulate material to fall vertically by gravity across a horizontal stream or flow of air. Assuming that all of the granules or particles are of approximately the same size (and hence experience approximately the same drag force from the moving air), granules or particles of greater mass will be accelerated more slowly by the moving air than those of lesser mass. As a result, the heavier granules or particles will fall closer to the initial drop point than the lighter granules or particles. By positioning hoppers or receptacles at these locations, the heavier and lighter granules or particles can be collected and processed separately. Examples of air separators can be found in U.S. Pat. Nos. 775,965 and 2,978,103. 
     In theory, air separation provides a useful way to separate lead bullets from backstop material of similar size in an environmental remediation operation of the type described above. In reality, however, there are a number of problems with the prior art approaches. For example, prior art air separators are generally designed to operate with small size granular or particulate materials, but the backstop material at an indoor remediation site is generally much larger in granule size than typically encountered with outdoor granular materials. This can result in poor separation between the backstop material and lead bullets. Still another problem with existing types of air separators is the fact that the prior art separators are bulky, are by design more complicated, require large amounts of space, and are not mobile. 
     Yet another difficulty with the prior art separators is that use of them with firearm training facilities sometimes requires shutting down the facility to move all the saturated backstop material to the prior art separator where separation of the bullets from the backstop material occurs. The cleaned backstop material can then be reused in the same facility, or sold as scrap or for some other purpose. 
     SUMMARY OF THE INVENTION 
     It is therefore a general object of the invention to provide a mobile material separator that will obviate or minimize problems of the type previously described. 
     A primary object of the present invention is provide an apparatus which is capable of separating a mixed backstop material into particles of at least two different specific gravities or ranges of specific gravity, and which can be adjusted to accommodate the specific characteristics of the mixed particulate material which is to be separated. As used herein, the term “particles” shall refer to any particulate or granular material containing granules, particles or other discrete components of at least two different specific gravities or ranges of specific gravity. 
     Another object of the invention is to provide a separation apparatus which is useful for separating lead bullets from backstop material as part of a remediation effort, and which is also useful for separating other types of mixed granular materials into their component parts. 
     A further object of the invention is to provide a separation apparatus which is useful for separating lead bullets from backstop material as part of a saturation remediation effort. 
     The present invention is also directed to methods for separating mixed particle material into particles of different sizes and/or specific gravities, and to methods for operating a mixed particle material separation apparatus to accommodate different types of and characteristics of mixed particle materials. These methods can be carried out using the exemplary apparatus disclosed and claimed herein. 
     A further object of the invention is to provide an apparatus for separating mixed particle material into particles of at least two different specific gravities or ranges of specific gravity, and which can operate in a continuous closed loop mode. 
     It is a further object of the invention to provide an apparatus for separating a mixed particulate material into particles of at least two different specific gravities or ranges of specific gravity. 
     A further object of the invention is to provide an apparatus for separating a mixed particulate material into particles of at least two different specific gravities or ranges of specific gravity, and which will place lighter material back in its original location. 
     A further object of the invention is to provide an apparatus for separating a mixed particulate material into particles of at least two different specific gravities or ranges of specific gravity, which will place the lighter material back to a more desirable location. 
     It is a further object of the invention to provide an apparatus for separating mixed particulate material into particles of at least two different specific gravities or ranges of specific gravity, wherein an air flow mechanism, tube, chamber size, and chamber length can be modified to accommodate materials of varied specific gravities. 
     It is a specific object of the invention to provide an apparatus for separating a mixed particulate material into particles of at least two different specific gravities or ranges of specific gravity, that can separate used bullets or other firearm projectiles from backstop material. 
     The above-described objects are realized by the present invention which relates to an apparatus for separating mixed particulate material into particles of at least two different specific gravities or ranges of specific gravity. In a preferred embodiment, the apparatus comprises an air compressor for providing compressed air into the discharge tube, which, through the venturi effect, creates a vacuum in a connecting hose. The connecting hose is connected to the top of a separation chamber wherein the mixed particulate material, which is vacuumed in by a vacuum hose, is separated and the heavier materials (higher specific gravity) fall into a hopper, while the light backstop material (lower specific gravity) is discharged from the discharge tube by virtue of the vacuum. In addition, the apparatus also comprises an air adjustment valve, automatic unloader valve, stand and discharge tube adjuster. In other embodiments of the invention, conveyor systems can be used to collect either or both the lower and higher specific gravity materials, and bring them to other more convenient locations. A number of different sensors can be added to the automatic unloader valve to determine when a pre-determined amount of higher specific gravity material has been collected. The entire operation of the apparatus can be controlled by a computer, which can also be connected through a network to other computers whereby the apparatus for separating materials can be operated remotely. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features and advantages of the present invention will best be understood by reference to the detailed description of the preferred embodiments which follows, when read in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram of a mobile air powered material separator in accordance with a first embodiment of the present invention; 
         FIG. 2  is a block diagram of a mobile air powered material separator in accordance with a second embodiment of the present invention; 
         FIG. 3  is a block diagram of an alternative unloader valve for the material separator in accordance with a third embodiment of the present invention; 
         FIG. 4  is a block diagram of an mobile air powered material separator in accordance with a fourth embodiment of the present invention; 
         FIG. 5  is a block diagram of a mobile air powered material separator in accordance with a fifth embodiment of the present invention; and 
         FIGS. 6A-E  illustrate several perspective views of a sixth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The various features of the preferred embodiments will now be described with reference to the drawing figures, in which like parts are identified with the same reference characters. The following description of the presently contemplated best mode of practicing the invention is not to be taken in a limiting sense, but is provided merely for the purpose of describing the general principles of the invention. 
       FIG. 1  is a block diagram of a mobile air powered material separator  100  in accordance with a first embodiment of the invention. The mobile air powered material separator (material separator)  100  is constructed to perform the following operations in one continuous closed loop: transport a mixed material comprising particles of different specific gravities; separate the transported material by specific gravity; and replace the lighter material back to its original location, or to a more desirable one. Airflow, tube and chamber size, and chamber length can be changed to accommodate materials of varied specific gravities. 
     Air compressor  10  is a commercially available air compressor, of which many different manufacturers are known in the industry. Preferably, though not necessarily, air compressor  10  will discharge air at a volume of 1200 CFM and 100 to 125 PSI. Compressed air from air compressor  10  is fed into four injector tubes  6 , which direct air into a discharge tube  2 . Using air adjustment valve  12 , the amount of compressed air feeding the injector tubes  6  can be varied to achieve desirable separation levels on materials with different specific gravities. Other CFM values can be used (for example 850 CFM can be used in other applications) than that mentioned above. These CFM values can be higher, as air adjustment valve  12  can regulate the flow of air from air compressor  10  into discharge tube  2 . The injector tubes  6  are placed in a manner so as not to restrict flow in the discharge tube  2 . As the air exits the discharge tube  2 , a resulting vacuum is created behind the injector tubes  6 . A higher CFM value yields a higher vacuum in the separation chamber  4 , angle of entry connection  26 , connecting hose  8  and discharge tube  2 . This vacuum is transferred to the separation chamber  4  by a connecting hose  8 . The separation chamber  4 , being larger in area, slows the air flow down. The air moves through material separator  100  from the bottom  5  to the top  7  of the separation chamber  4 . As a result of the design of the separation chamber  4 , angle of entry connection  26  and the venturi effect upon both of those items, there is little or no air flow velocity in the separation chamber  4  at any point just below the location where the angel of entry connection  26  intersects with the separation chamber  4 . 
     Material  32  will enter the separation chamber  4  through the angle of entry connection  26  via vacuum hose  30 . Angle of entry connection  26  is located at the lower portion  9  of the separation chamber  4 . The vacuum created by air moving through injector tubes  6 , into discharge tube  2 , draws material  32  through the vacuum hose  30  into the separation chamber  4 . Material  32  is generally composed of a mixture of lower specific gravity material  34  and higher specific gravity material  28 . In an exemplary embodiment of the present invention, the material separator  100  is used to clean backstop material of bullets in firearms training or practice facilities. In this case, therefore, the lower specific gravity material  34  are the particles of rubber (or granulated rubber backstop material  55 ) and the higher specific gravity material  28  are bullets  57 . The combination of bullets  57  and granulated rubber backstop material  55  is the material  32 . 
     The angle at which angle of entry connection  26  makes with respect to separation chamber  4  is important for proper functioning of material separator  100 . If, for example, the angle between angle of entry connection  26  and separation chamber  4  is 90°, then little or no material would travel up separation chamber  4 . This results because the vacuumed material  32  travels straight into separation chamber  4  and strikes the opposite wall; the vacuumed material  32  has no upward velocity vector. While it can be possible to attach a sufficiently large air compressor  10  to the material separator  100  to draw vacuumed material  32  up the separation chamber  4  even in that extreme circumstance, such an embodiment would not be preferred. On the other extreme, if the angle between angle of entry connection  26  and separation chamber is 0° (i.e., pointing straight up), then it is possible that no separation of material will occur, as the material with higher specific gravity (i.e., the bullets) do not strike the inner wall of separation chamber  4  which causes them to slow down, and thus do not fall onto automatic unloader valve  20 . Thus, there are a range of angles that the angle of entry connection  26  can make with separation chamber  4 . Preferably, the angle between the angle of entry connection  26  and the separation chamber  4  should be between 40° and 50°. More preferably, the angle between the angle of entry connection  26  and the separation chamber  4  should be at or about 45°. Though the angle between the angle of entry connection  26  and the separation chamber  4  can be made variable, in the preferred embodiment of the present invention it is fixed at the time of assembly of the material separator  100  to be at or about 45°. 
     The vacuum created by air compressor  10  and injector tubes  6  draws vacuumed material  32  up through vacuum hose  30 , and into separation chamber  4 , through angle of entry connection  26 . As discussed above, because angle of entry connection  26  is at an angle to separation chamber  4 , vacuumed material  32  will have both an upward and horizontal velocity component, therefore causing the vacuumed material  32  to strike against the inner wall of separation chamber  4 . This causes the vacuumed material  32  to slow down somewhat, allowing the lower specific gravity material  34  to continue up the separation chamber  4 , and the higher specific gravity material  28  to fall to the bottom  5  of the separation chamber  4 . The lower specific gravity material  34  continues up the separation chamber  4 , through connecting hose  8 , and is then expelled out of the discharge tube  2 . Alternatively, the discharged lower specific gravity material  34  can be piped to some other desirable location. The higher specific gravity material  28  builds up in the bottom of the separation chamber until the weight of the build-up opens the automatic unloader valve  20 . In a first embodiment of the present invention, the amount of build-up of higher specific gravity material  28  and the amount of time between successive openings of the automatic unloader valve  20  is controlled by the position of a counterweight  18  on the valve arm  16 . In another embodiment of the present invention, the automatic unloader valve  20  is opened by a pneumatic piston  75  (that runs on compressed air), that is timed to open at a determinable interval. This is shown and described in greater detail with respect to  FIGS. 6A-E  below. The determinable interval is preferably set to six seconds, but can be changed depending upon the particular circumstances and operating conditions. In this additional embodiment of the present invention, level sensor  70  (operation of which in conjunction with an unloader valve assembly  71  is described in greater detail with respect to  FIG. 3  below), can be omitted since emptying of the separation chamber  4  is accomplished on an adjustable timed basis. 
     The one-step material separator  100  has particular utility in shooting ranges in which the backstop is comprised of small rubber pieces. The material separator  100  vacuums the rubber and bullets off the range, separates the bullets, and blows the rubber pieces back, all in one continuous processing loop. Frame  22  and air compressor  10  can be combined as an integral unit in the material separator  100 , and can be fabricated small enough to enter through a standard sized door and wheeled into position. The material separator  100  can separate other materials with different specific gravities, such as sand and bullets, or paper and bullets, among other combinations. The material separator  100  is advantageous over prior art systems because of its continuous operating properties and its integral, mobile structure. 
       FIG. 2  is a block diagram of a mobile air powered material separator  200  in accordance with a second embodiment of the invention. Although the first embodiment of the invention shown in  FIG. 1  operates very well (up to 95% efficiency in separating the lower specific gravity material  34  from the higher specific gravity material  28 ) in some applications, it can be necessary to further cleanse the lower specific gravity material from the higher specific gravity material. This can be especially true in firearm training facilities that have not had their backstop material cleaned for extended periods of time. In this case, there is an alternative method for further cleansing of the backstop material. Shown in  FIG. 2  are conveyor belt  62 , second discharge tube  50 , air cone adapter  56  and second air hose  58 . As the highly cleansed higher specific gravity material  59  falls to the bottom of separation chamber  4 , it falls onto conveyor belt  62 . There can be an automatic unloader valve  20  as in the first embodiment illustrated in  FIG. 1  (or unloader valve assembly  71  discussed below), but that is not required. 
     Once the highly cleansed higher specific gravity material  59  falls onto conveyor belt  62 , it is carried at an incline of first angle  38  to the top of the conveyor belt  62 , where it falls off the conveyor belt  62  through a hopper  63  then through hole  52  in second discharge tube  50 . First angle  38  can be between 30° and 40°, but is preferably at or about 35°. The material separator  200  can be manufactured such that first angle (as well as second angle  40 , discussed below) is field-adjustable, but, in a preferred embodiment of the present invention, the first and second angles  38  and  40  are set at time of manufacture and are not adjusted in the field. A second hopper can be placed at the bottom  5  of separation tube  4  to guide the highly cleansed higher specific gravity material  59  onto the conveyor belt  62 . Thereafter, a guide can be placed to spread out the highly cleansed higher specific gravity material  59  on the conveyor  62 . The guide and second hopper are not shown in  FIG. 2 . Placed within the lower end  51  of second discharge tube  50  is an air cone adapter  56 . There is a space between air cone adapter  56  and the floor of lower end  51  of second discharge tube  50 . Generally, the air cone adapter  56  is approximately half the diameter of the second discharge tube  50 , though that ratio is not critical. 
     Attached to the end of air cone adapter  56  is second air hose  58 , which is attached to air compressor  10 . Air is forced through second air hose  58  into air cone adapter  56  which causes the air to flow through the second discharge tube  50  and out the upper end  53  of second discharge tube  50 . As the highly cleansed higher specific gravity material  59  falls through hole  52 , the higher specific gravity material (in this instance, bullets  57 ) falls down second discharge tube  50 , under air cone adapter  56 , and out of second discharge tube  50  into container  54 . The air being forced through air cone adapter  56  and second discharge tube  50  causes the lower specific gravity material (in this instance, the granulated rubber backstop material  55 ) to be discharged forcibly from the upper end  53  of second discharge tube  50 . The result is that the material falling from the second discharge air tube  50  (bullets  57 ) is extremely clean; in many instances over 99% free of the lower specific gravity material  34  (granulated rubber backstop material  55 ). 
     A small space between air cone adapter  56  and the floor of second discharge tube  50  is maintained so that the highly cleansed higher specific gravity material  59  can fall out of second discharge air tube  50  into container  54  (which can have wheels as shown for convenient transport). In a preferred embodiment of the present invention, the container  54  is a 30 gallon drum that rests on a pallet, so that an operator can move it. By way of example, the pallet and drum can weigh approximately 1000 lbs. when the drum is two-thirds filled with used bullets. The operator will use a pallet jack to move the partially filled drum and pallet. 
       FIG. 3  is a block diagram of an alternative unloader valve for the material separator in accordance with a third embodiment of the invention. In the embodiment illustrated in  FIG. 3 , the automatic unloader valve  20  of  FIG. 1  has been replaced with unloader valve assembly  71 , which is comprised of unloader valve  72 , valve servo  74 , level sensor  70 , computer  78  and can include a communications network  80 . In this embodiment of the present invention, the level sensor  70  determines when it is time to empty separation tube  4 . The level sensor  70  can be a weight sensor, an optical sensor, or even operate by an indirect measurement, such as an electrical characteristic (resistance, capacitance or inductance), as well as many other types of sensing mechanisms. 
     Operation of unloader valve assembly  71  begins with level sensor  70  reporting to computer  78  its measurements. When the measurement reaches or surpasses a predefined point, computer  78  transmits a signal to valve servo  74 , which opens unloader valve  72 , causing the higher specific gravity material  28  to fall away from separation tube  4 . In this case, there can be a conveyor which carries the higher specific gravity material  28  away from the immediate area. In some cases, computer  78  can completely control material separator  100 , such that it operates automatically. Computer  78  can be in communications with other computers via network  80 . A remote computer (not shown) can operate material separator  100  via network  80  and computer  78 . 
       FIG. 4  is a block diagram of an mobile air powered material separator  400  in accordance with a fourth embodiment of the invention. Material separator  400  shown in  FIG. 4  combines two material separators  100  from  FIG. 1 , with a slight modification. In the material separator  400  of  FIG. 4 , the first material separator  100   a  is configured as discussed above, that is, vacuumed material  32  enters the separation chamber  4   a  through angle of entry connection  26   a . The separation chamber  4   a  discharges the lower specific gravity material  34  through discharge tube  2   a , and the higher specific gravity material  28  is dropped to the bottom  5   a  of separation tube  4   a  where it is then deposited into bin  82   a.    
     However, not all the material dropped into bin  82   a  is higher specific gravity material  28 ; there is some lower specific gravity material  34  mixed in. Thus, the second material separation tube  4   b  is configured as shown to further cleanse the mixed material. Second material separator  100   b  is slightly different from the first material separator  100   a  in that its angle of entry connection  26   b  is sloped downward and into separation chamber  4   b  as opposed to upward and into separation chamber  4   a  of material separator  100   a . In one embodiment of the present invention, the diameter D 2  of the second separation chamber  4   b  is smaller than the diameter D 1  of the first separation chamber  4   a . However, in a preferred embodiment of the present invention, the diameters of the two separation chamber  4   a  and  4   b  are substantially the same. In this case, the air flow in the second separation chamber  4   b  is adjusted to be less than the air flow in the first separation chamber  4   a . The reason for this is because the material entering the second separation chamber  4   b  is much cleaner than the material than that which entered the first separation chamber  4   a , there does not have to be as much air flow, or vacuum in the second separation chamber  4   b . This conserves the air flow needed from air compressor  10 , making the configuration more efficient Also, the second separation chamber  4   b  can be shorter than the first separation chamber  4   a.    
     As the highly cleansed higher specific gravity material  59  leaves the first separation chamber  4   a , it is deposited in first bin  82   a , and then is drawn into the second angle of entry connection  26   b  from the vacuum developed through the second separation chamber  4   b  (although the air hoses  14 , air compressor  10  and other elements shown in  FIG. 1  have not been shown in  FIG. 4 , creation of the vacuum through the venturi effect occurs just as described in detail above). Also, there can be a vibrator plate (not shown in  FIG. 4 ) on the bottom of bin  82   a  which would assist the travel of the highly cleansed higher specific gravity material  59  down the slope of the bottom of the first bin  82   a  into the second angle of entry connection  26   b . The highly cleansed higher specific gravity material  59  that enters into the second separation chamber  4   b  through the second angle of entry connection  26   b  is acted upon by the vacuum that is present in the second separation chamber  4   b . The higher specific gravity material  28  falls to the bottom  5   b  of the second separation chamber  4   b  (bullets  57 ), and then is deposited into second bin  82   b . The lower specific gravity material  34  is forced upward through the second separation chamber  4   b , and out directional discharge nozzle  60 . This places the lower specific gravity material  34  (in the case of the firearms facility, granulated rubber backstop material  55 ), to its original location. The unloader valve assembly  71  of  FIG. 3  can be used in the material separator  400  of  FIG. 4 , and the entire assembly of material separator  400  can also be placed on one frame  22 , as shown and described in reference to  FIGS. 6A-E . 
       FIG. 5  is a block diagram of a mobile air powered material separator  500  in accordance with a fifth embodiment of the invention. The embodiment illustrated in  FIG. 54  is used when it is necessary to clean the mixed material extremely well. Although the embodiment of  FIG. 5  shows three material separators,  100   a ,  100   b  and  100   c  connected together, it will be apparent to one skilled in the art that there is no limit as to how many material separators  100  can be connected in such a series arrangement. 
     In  FIG. 5  first material separator  100   a  vacuums mixed material  32  in the normal manner as described above. Eventually, lower specific gravity material  34  is discharged via discharge tube  30   a , and higher and some lower specific gravity material  28  and  34  is deposited into bin  82   a . This material is referred to as first highly cleansed higher specific gravity material  59   a . Once bin  82   a  reaches a certain level, second material separator  100   b  is engaged (perhaps through unloader valve assembly  71 ), vacuums the first highly cleansed higher specific gravity material  59   a  into separation chamber  4   b  and performs the separation process again, as described above. In this instance, however, the material deposited into bin  82   b  is even more highly separated and is very nearly all higher specific gravity material  28 . This material is second highly cleansed higher specific gravity material  59   b . But, in some instances, that might not be sufficient, and hence a third material separator  100   c  is engaged, again separating the lower specific gravity material  34  from the higher specific gravity material  28 . Then, what is discharged from discharge tube  2   c  is lower specific gravity material  34 , and substantially only higher specific gravity material  28  is deposited into bin  82   c  (third highly cleansed higher specific gravity material  59   c ). 
     It is possible, using the embodiment illustrated in  FIG. 5 , to separate four or more different specific gravity materials. Since the output of air compressor  10  can be calibrated for each material separator  100 , different flow levels can be established through use of air adjustment valves  12   a - c . The operation of the embodiment shown in  FIG. 4  would then be as follows. Material  32  contains four materials, with specific gravities g 1 , g 2 , g 3  and g 4 , respectively. Specific gravity g 1  is greater than g 2 , g 2  is greater than g 3 , and g 3  is greater than g 4 . Thus, the material with specific gravity g 1  is the heaviest, and the material with specific gravity g 4  is the lightest. Air flow  110   a , established through air compressor  10 , air adjustment valve  12   a  and air tube  14   a , is strong enough to only vacuum the material with specific gravity g 4  up separation tube  4   a . The materials with specific gravities g 1 , g 2  and g 3  fall into bin  82   a , as described above (first highly cleansed higher specific gravity material  59   b ). Material  34   a  with specific gravity g 4  is then discharged through discharge tube  2   a.    
     The process repeats in material separator  100   b . First highly cleansed higher specific gravity material  59   a  is vacuumed into second separation chamber  4   b . Here though, air flow  110   b , established through air compressor  10 , air adjustment valve  12   b  and air tube  14   b , is strong enough to only vacuum material with specific gravity g 3  and what remains of the material with specific gravity g 4  up separator tube  4   b . Material  34   b  with specific gravities g 3  and g 4  is then discharged through discharge tube  2   b . Materials with specific gravities g 1  and g 2  fall into bin  82   b  (along with a substantially lesser amount of materials with specific gravities g 3  and g 4 ). This is second highly cleansed higher specific gravity material  59   b . Material separator  100   c  then vacuums materials with specific gravities g 1  and g 2 , and the substantially lesser amounts of materials with specific gravities g 3  and g 4  (second highly cleansed higher specific gravity material  59   b ) into separator tube  4   c . Air flow  110   c , established through air compressor  10 , air adjustment valve  12   c  and air tube  14   c , is strong enough to only push material with specific gravity g 2  (and materials with specific gravities of g 3  and g 4 ) up separation tube  4   c . The heaviest material, with specific gravity g 1  (third highly cleansed higher specific gravity material  59   c ), is in bin  82   c , and the material with specific gravity g 2  (along with whatever remains of materials with specific gravities g 3  and g 4 ) is discharged via discharge tube  2   c  (material  34   c ). Through operation of three material separators, four different materials have been separated: material with specific gravity g 4  through discharge tube  34   a ; material with substantially only specific gravity g 3  through discharge tube  34   b ; material with substantially only specific gravity g 2  through discharge tube  34   c , and material with substantially only specific gravity g 1  rests in bin  82   c . Of course, further refinement can take place by combining the embodiment of  FIG. 2  with the embodiment of  FIGS. 4 and 5 . 
       FIGS. 6A-E  illustrate several perspective views of a sixth embodiment of the present invention. In  FIGS. 6A-E , many of the components of the previous embodiments have been utilized, along with some new ones, in order to create a more compact, versatile material separator  600 . The material separator  600  shown in  FIGS. 6A-E  comprises a frame  22 , onto which is assembled a separation chamber  4  (attached to which is angle of entry connection  26  and unloader valve  72 ), a conveyor  62 , air hoses  14   a - c , second discharge tube  50 , an air cone adapter  56 , second air hose  58  (attached to an air compressor  10 ), hopper  63  and second hopper  77 . 
     Operation of the material separator  600  of  FIGS. 6A-E  is essentially the same as that discussed in  FIG. 2 . As the highly cleansed higher gravity material  59  falls to the bottom of separation chamber  4 , it falls onto conveyor belt  62 . There can be an automatic unloader valve  20  as in the first embodiment illustrated in  FIG. 1 , but that is not required. 
     Once the highly cleansed higher gravity material  59  falls onto conveyor belt  62 , it is carried at a third angle  42  of inclination of between 30° and 40° to the top of the conveyor belt  62 , where it falls off the conveyor belt  62  through a hopper  63  into second discharge tube  50 . Preferably, the third angle  42  of inclination of the conveyor  62  is at or about 35°. Though the third angle  42  of inclination of the conveyor  62  can be varied, in a preferred embodiment of the present invention, the third angle  42  of inclination of conveyor  62  is fixed to be at or about 35° when the material separator  100  is assembled. A second hopper  77  is located at the bottom  5  of separation tube  4 , to guide the highly cleansed backstop material  59  onto the conveyor belt  62 . Thereafter, a guide can be placed to spread out the highly cleansed backstop material on the conveyor  62 . The guide is not shown in  FIGS. 6A-E . Placed within the lower end  51  of second discharge tube  50  is air cone adapter  56 . There is a space between air cone adapter  56  and the floor of the second discharge tube  50 . Generally, the air cone  56  is approximately half the diameter of the second discharge tube  50 , though that ratio is not critical. 
     Attached to the end of air cone adapter  56  is second air hose  58 , which is attached to air compressor  10 . Air is forced through second air hose  58  into air cone adapter  56  which causes the air to flow through the second discharge tube  50  and out the upper end  53  of second discharge tube  50 . As the highly cleansed higher specific gravity material  59  falls through the hopper  63 , substantially all of the higher specific gravity material  59  (in this instance, bullets  57 ) falls down second discharge tube  50 , under air cone adapter  56 , and out of second discharge tube  50  into a container  54  (container  54  is not shown in  FIGS. 6A-E ). The air being forced through air cone adapter  56  and second discharge tube  50  causes the lower specific gravity material  34  (in this instance, the granulated rubber backstop material  55 ) to be discharged forcibly from the upper end  53  of second discharge tube  50 . The result is that the material discharged from the second discharge air tube  50  is comprised of the lower specific gravity material  34 , and the material that falls from second discharge tube  50  into container  54 , higher specific gravity material  28  (bullets  57 ) is extremely clean; in many instances over 99% free of the lower specific gravity material  34  (granulated rubber backstop material  55 ). 
     Third angle  42  represents the angle by which the conveyor belt  62  is inclined from the horizontal, and fourth angle  44  is the angle by which the second discharge tube  50  is inclined from the horizontal. In a preferred embodiment of the invention, the third angle  42  is at or about 35°, and fourth angle  44  is at or about 45°. As discussed above, while the fourth angle  44  can be made to be field adjustable, in the preferred embodiment of the present invention, the fourth angle  44  is fixed at the time of manufacture of the material separator  600  to be at or about 45°. 
     Container  54 , in a preferred embodiment of the present invention, is a 30 gallon drum that rests on a pallet, so that an operator can easily move it. By way of example, the pallet and drum can weigh approximately 1000 lbs. when the drum is two-thirds filled with used bullets. The operator will use a pallet jack to move the partially filled drum and pallet. In another embodiment of the present invention, as discussed above, container  54  itself can have wheels for convenient transport, 
     The present invention has been described with reference to certain exemplary embodiments thereof. However, it will be readily apparent to those skilled in the art that it is possible to embody the invention in specific forms other than those of the exemplary embodiments described above. This may be done without departing from the spirit and scope of the invention as defined in the appended claims and equivalents thereof. The exemplary embodiments are merely illustrative and should not be considered restrictive in any way.