Abstract:
An apparatus for rotary dumping of rail cars, including a material receiving pit. A rotational frame is disposed at least partially in the pit, is configured to dump a load from a rail car during rotational motion. A backside airflow diverter is disposed within the pit along with a backside hood for removing contaminated air. At least one baffle contacts the upper surface of the backside airflow diverter during at least a portion of the rotational motion. The invention includes an end of hood close off panel extending substantially from a platen supporting wall to the backside air flow diverter or an end ring baffle that extends from a grizzly upwardly to approximately the perimeter of a supporting ring and from the backside airflow diverter toward a dump side of the pit whereby dust laden air is substantially prevented from escaping from the pit under the end ring baffle.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of application Ser. No. 11/981,618 filed Oct. 31, 2007 which is a continuation of application Ser. No. 11/235,655 filed Sep. 26, 2005 now U.S. Pat. No. 7,322,785, which is a continuation-in-part of application Ser. No. 10/159,808, filed May 31, 2002 now U.S. Pat. No. 6,960,054, which claims the benefit of U.S. Provisional Application No. 60/294,809 filed May 31, 2001 all of which are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to rotary-dumping of material from rail cars, and more particularly, to a method and apparatus for controlling environmental contamination produced by rotary-dumping material from rail cars. 
       BACKGROUND OF THE INVENTION 
       [0003]    Rail cars have been used for many years to efficiently haul large quantities of bulk materials over land. Items commonly shipped include grain, iron ore and coal. Shipping such items via rail car is very efficient due to the ability to transport extremely large loads of these materials in one shipment. For example, one single rail car may hold up to 110 tons of coal and an entire train made up of such cars may be over 130 cars in length, extending 6000 feet in total length. 
         [0004]    Once at the destination, it is necessary to unload the cargo. For bulk material such as grain, ore, or coal, bottom-dumping and rotary-dumping are commonly used. Bottom-dumping involves staging a particular car over a receiving pit and opening hatches located in the bottom of the car. The cargo exits the car though the bottom hatches or doors and proceeds into the pit below. U.S. Pat. No. 5,302,071, assigned to Svedala Industries, Inc., discloses one example of a bottom-dumping rail car. 
         [0005]    Bottom-dumping requires the use of rail cars that are specifically designed for bottom-dumping. This is due to the need to direct the car contents to a centrally located chute on the bottom of the car. The sides of the car must be at least partially sloped to urge the contents towards the chute, or else there would be a partial retention of the material being carried. This configuration decreases the ratio of the car&#39;s size vs. cargo capacity. Additionally, the bottom-dump configured rail cars are not easily interchangeable with standard cars at a dumpsite because the dump apparatus for standard cars must be uniquely configured to accommodate bottom-dump cars. The bottom-dump rail cars are also environmentally disadvantageous, as will be described more fully below. 
         [0006]    Rotary-dumping is the other commonly used method of unloading a rail car. In rotary-dumping, a standard rectangular rail car is staged or indexed in a rotary-dump apparatus. The apparatus then rotates approximately one-half turn, thereby dumping the contents of the car into a receiving pit. Typically, the cars of the train remain connected during the dumping process through the use of rotary couplings between each car. Such couplings permit the cars to be rotated while still connected though an axis center at the coupling. U.S. Pat. Nos. 4,479,749 and 4,609,321, both assigned to Dravo Corporation, disclose conventional rotary-dump apparatuses. In some applications, such as the dumping of coal at major power plants, cars may be rotated and emptied at the rate of one car every four minutes. 
         [0007]    Environmental pollution is an important concern to the design of a material dumping facility. When the car&#39;s load is dumped, a large quantity of material exits the car in a very short time. The turbulence generated by the quick unloading causes fine dust particles to billow up from the receiving pit and pollute the air surrounding the dump facility. The resulting dust, such as from grain or coal, is very explosive when in sufficient density. It is also an environmental pollutant. Therefore, there is a need to provide an apparatus and method for minimizing the polluting effect of dust. 
         [0008]    Bottom-dump apparatuses have two critical drawbacks. First, they require special cars equipped with the bottom chutes as discussed previously. Second, the dust cloud produced by bottom-dumping is recognized by those skilled in the art to be larger, more aggressive and less controllable than the cloud produced by the rotary-dump method. 
         [0009]    Rotary-dump systems control the dust cloud by using fans with large motors to exhaust the dust-filled air surrounding the car though conduits and into filtering devices. This process requires a very high flow of air and correspondingly very large motors to drive such high capacity system. These motors are commonly several hundred horsepower. Multiple motors of this size may be required at any given installation. 
         [0010]    The cloud is typically large enough and aggressive enough to overpower any given removal system. Therefore, the airflow around the car and in the pit is controllably designed to keep the dust cloud suppressed long enough to allow the dust collection system to suck the dust from the surrounding area. The better the airflow is managed, the less horsepower is needed to drive the system. This results in greatly improved efficiency. 
         [0011]    The Dravo patents listed above disclose a method of enclosing a rail car within a fixed enclosure. This design has several drawbacks. First, it restricts the operator&#39;s ability to observe the load as it is being dumped to ensure that the system does not malfunction and that no impurities or foreign objects are introduced into the pit. Next, the fixed enclosure requires multiple large motors to drive the plurality of air handling units. The filtering portions of the air handling units are within the dumping facility, which makes cleaning and maintenance more difficult. The presence of the air filtering units in the dumping facility exposes the facility to the risk of damage due to the force of explosions that sometimes occur in the filtering assemblies. Finally the efficiency of the system is low due to the large motors required to produce sufficient air removal capacity because the control of the airflow around the car does not have good dust cloud retention time. 
         [0012]    There are two different types of rotary car dumpers in common use. Those skilled in the art refer to the two types of dumpers as rings out dumpers and rings in dumpers. The rings referred to are the structural ends of a car dumper which support the entire car dumper barrel and the railcar itself. Depending upon the design of a rotary car dumper it may have the rings located at the far ends of the dumper barrel, a rings out design, or it may have the rings located approximately one quarter of the length of the barrel in from the ends, the rings in design. 
         [0013]    When a railroad car is dumped more air is displaced by the rush of product exiting the railcar than can be evacuated by a blower system in a period of time during the dump. Thus, there is a tendency for the moving dust laden air to escape from the car dumper pit by any exit path that may be available. 
         [0014]    In the case of a rings out car dumper the dust laden air tends to escape beneath the end ring and travel upward between the end ring and the dumper pit wall. Thus, the dump creates an upward escaping cloud of dust laden air above track level. For reasons of air quality and environmental protection it is desirable to maintain the dust laden air beneath the track level within the dump pit area. Dust laden air that is above track level is harder to control and direct to a blower system for transport to a dust filter house. 
         [0015]    In the case of a rings in car dumper, the dumper pit is often design with a portion of the dumper pit wall extending under the center line of the track. This wall extension is in place to support the trunions that, in turn support the supporting rings and thus the dumper barrel and dumper platen. This wall extension beneath the dumper barrel prevents dumper mounted baffles from extending to the extreme ends of the dumper pit because the dumper mounted baffles would interfere with the protruding wall while rotating. This arrangement creates a gap between the dumper pit wall and the baffles that is equal to the thickness of the wall extension that supports the dumper barrel. 
         [0016]    Therefore, there is a continuing need to provide a rotary-dumper dust collection apparatus and system that overcomes the drawbacks of the prior art. 
       SUMMARY OF THE INVENTION 
       [0017]    The present invention addresses the disadvantages in the prior art and the need to provide an environmentally friendly and efficient way to unload rail cars by providing a method and apparatus for controlling dust generated by the rotary dumping of rail cars. One or more flexible baffles are provided to the back-side of a rotary dump frame to seal a portion of the material receiving pit during a portion of the rotary motion. The dust cloud generated by this dumping is retained in the pit for an increased time due to tumbling of the cloud induced by the baffles and other features of the facility. A plurality of intake ducts removes the dust cloud from the pit for transfer to a remote filtering facility. 
         [0018]    In a rings out dumper to prevent air from escaping beneath the end ring and traveling upward between the end ring and the dumper pit wall, the present invention includes an end ring baffle that protrudes from the grizzly to above the perimeter of the dumper end ring. The end ring baffle seals to the ski jump of the backside hood and extends toward the opposite side of the dump pit, sufficiently to prevent any airflow from escaping beneath the end ring. Thus, the end ring baffle extends from the backside hood toward the dump side of the pit. The precise length of the end ring baffle is determined by the dumper and pit design. The end ring baffle is fit to the grizzly which forms the reticulated top of the dumper pit hopper so that any air from the hopper is channeled upward past the perimeter of the end ring so that is unable to escape beneath the end ring. 
         [0019]    In the case of the rings in dumper, the present invention includes an end of hood close off panel. The end of hood close off panel extends from the barrel support wall to the ski jump of the backside hood. Thus, the end of hood close off panel creates a barrier to prevent dust laden air from escaping the dust containment area. As moveable baffles suspended from the dumper drum rotate around they first make contact with the platen support wall and then engage the end of hood close off panel as they leave the wall. This creates a continuous seal for the remainder of the rotation of the dumper which prevents dust laden air from escaping around the end of the baffle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a side detail view of a rotary-dump facility according to an embodiment of the present invention; 
           [0021]      FIG. 2  is a top view of a rotary-dump facility according to an embodiment of the present invention; 
           [0022]      FIG. 3  is a sectional view of a rotary-dump apparatus with airflow control features according to an embodiment of the present invention; 
           [0023]      FIG. 4  is a sectional view of the rotary-dump apparatus of  FIG. 3  in partial rotation; 
           [0024]      FIG. 5  is a sectional view of the rotary-dump apparatus of  FIG. 3  in partial rotation; 
           [0025]      FIG. 6  is a sectional view of the rotary-dump apparatus of  FIG. 3  in partial rotation; 
           [0026]      FIG. 7  is a sectional view of the rotary-dump apparatus of  FIG. 3  in partial rotation; 
           [0027]      FIG. 8  is a sectional view of the rotary-dump apparatus of  FIG. 3  at full rotational travel; 
           [0028]      FIG. 9  is a sectional view of a rotary-dump apparatus with airflow control features according to an embodiment of the present invention at partial rotation; 
           [0029]      FIG. 10  is a sectional view of the rotary-dump apparatus of  FIG. 9  in partial rotation; 
           [0030]      FIG. 11  is a sectional view of the rotary-dump apparatus of  FIG. 9  at full rotational travel; 
           [0031]      FIG. 12  is a partial detail end view of a rotary-dump apparatus according to an embodiment of the present invention; 
           [0032]      FIG. 13  is a detail end view of a rotary-dump frame with baffle according to an embodiment of the present invention; 
           [0033]      FIG. 14  is a detail view of a baffle according to an embodiment of the present invention; 
           [0034]      FIG. 15  is a detail end view of a rotary-dump frame with baffle according to an embodiment of the present invention; 
           [0035]      FIG. 16  is a detail view of a baffle according to an embodiment of the present invention; 
           [0036]      FIG. 17  is a detail view of a baffle according to an embodiment of the present invention; 
           [0037]      FIG. 18   a  is a side elevational view of a baffle for a rotary-dump apparatus according to an embodiment of the present invention; 
           [0038]      FIG. 18   b  is a side elevational view of a baffle for a rotary-dump apparatus according to an embodiment of the present invention; 
           [0039]      FIG. 19  is a sectional side view of a rotary-dump apparatus according to an embodiment of the present invention taken along line  2 - 2  of  FIG. 2 ; 
           [0040]      FIG. 20  is a sectional side view of a rotary-dump apparatus according to an embodiment of the present invention taken along line  3 - 3  of  FIG. 2 ; 
           [0041]      FIG. 21  is a partial top detail view of a rotary-dump apparatus according to an embodiment of the present invention; 
           [0042]      FIG. 22  is a partial top detail view of a rotary-dump apparatus according to an embodiment of the present invention; 
           [0043]      FIG. 23  is a sectional view of a rings out rotary dump apparatus in accordance with the present invention; 
           [0044]      FIG. 24  is a sectional view taken along elevational line  24 - 24  of  FIG. 23 ; 
           [0045]      FIG. 25  is a sectional view taken along section line  25 - 25  of  FIG. 23 ; 
           [0046]      FIG. 26  is a sectional view taken along section line  26 - 26  of  FIG. 23 ; 
           [0047]      FIG. 27  is a detailed sectional view taken from  FIG. 26 ; 
           [0048]      FIG. 28  is a sectional view of a rings in rotary dumper in accordance with the present invention; 
           [0049]      FIG. 29   a  is a front elevational view of an end of hood close off panel in accordance with the present invention; 
           [0050]      FIG. 29   b  is an end elevational view of end of hood close off panel; 
           [0051]      FIG. 29   c  is a plan view of end of hood close off panel; 
           [0052]      FIG. 30  is a schematic plan view of a rings out rotary dumper facility; and 
           [0053]      FIG. 31  is a schematic plan view of a rings in rotary dumper facility. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0054]    Referring to  FIGS. 1 and 2 , a material dumpsite  50  is shown. Throughout this description, reference will be made to the configuration of the present invention for use at a coal dumping facility. However, the invention is well suited to the dumping of a wide range of dust producing materials, such as ore and grain. 
         [0055]    The coal dumpsite  50  generally comprises a dumping facility  52  and a filter facility  54 . The material to be dumped enters the dump facility  52 , which is a rotary-type dump facility. The dumping of this material produces a dust cloud, which is sucked through ductwork and transferred to the filter facility  54  through air transfer ducts or conduits  56 . 
         [0056]    The filter facility  54 , also known as a bag house, functions to separate the coal dust particles from the air to prevent environmental contamination and the possibility of explosion. Bag houses  54  generally comprise an upper portion  55  and a lower portion  57  separated by a filter membrane assembly (not shown). The contaminated air is drawn through the filter assembly, and the filter assembly traps the contaminants in the lower portion  57  of the filter facility. Filtered air proceeds to the upper portion  55  of the filter facility  54  and exits through filtered air exit  58 . The filtered air arrives at fan housing  62  and finally exits through a clean air exhaust duct  60 . A drive motor  64  powers a fan (not shown) within fan housing  62 . The drive motor  64  rotates the fan, which causes air to rapidly move through the entire system as described hereinabove. The negative pressure created within the system, located prior to the fan housing, drives the system by drawing the contaminated air into the system of the rotary-dump facility  52 . 
         [0057]    A contaminant particle collector  68  is disposed within filter facility  54  and in communication with the facility lower portion  57  to collect the contaminant particles that accumulate on the filtering assembly. From time to time, the filtering assembly may be vibrated or flushed with a reverse flow of air in order to remove accumulated contaminants. The filter assemblies and filter facility  54 , as described herein, are more fully described in co-pending U.S. patent Ser. No. 10/037,319, which is hereby incorporated by reference. 
         [0058]    The filter facility  54  may comprise more than one fan housing  62  and drive motor  64 , as shown in  FIG. 2 . The ultimate number of drive motors depends on the capacity of the system in the particular installation and size of the individual motors utilized. A plurality of explosion vents  66  is provided to each of the upper and lower portions of the bag house  54 . 
         [0059]    In the event that a fire or explosion might occur in the bag house  54 , the explosion vents  66  minimize potential damage. The powder from coal or grain dust is highly explosive, as discussed previously. The explosion vents  66 , in conjunction with a remote filter facility  54  avoid damage to the dumping facility  52 , which is in contrast to a dumping facility that encloses the filtering facility within the same housing as the dump facility. 
         [0060]    Referring to  FIG. 3 , the coal dump facility  52  is shown with a coal car  69  in the upright configuration. The contaminated air enters the transfer duct  56  through a plurality of air inlet conduits  70 ,  72 . The dump-side intake  70  is located on the side closest to the direction of the dumping and the back side intake  72  is located approximately opposite the dump-side intake  70 . Each intake  70 ,  72  terminates in a respective dump-side hood  74  and backside hood  76 . The intakes  70 ,  72  exhaust the contaminated air that emanates from the pit  78 , which is located directly below the rotational dumping frame  80 . Each of the intakes  70 ,  72  spans the length of the pit  78 , as will be described below. 
         [0061]    The pit  78  presents a plurality of features to cooperate in controlling the movement of the dust cloud produced by a dumping activity. A dump-side diverter  82  is positioned on the dumping side of the pit  78 . The dump-side diverter  82  functions to both direct the flow of material being dumped, and to direct the airflow inside the pit  78 . A backside airflow diverter  84  is positioned in the pit  78  approximately opposite of the dump side diverter  82 . The backside diverter  84  is also referred to as the ski jump, due to the resemblance of its general shape. 
         [0062]    The ski jump  84  comprises a curved upper surface  86  and lower surface  88 . The backside hood  76  exhausts the dusty air from the pit  78  from beneath the lower surface  88  of the ski jump  84 . The sloped upper surface  86  cooperates with features on the rotational frame  80  to seal the backside of the frame  80  and control the airflow during a dumping operation. 
         [0063]    A dump-side hood baffle  90  protrudes from a portion of the side of the dump side hood  74 . This baffle  90  is a flexible rubber member that spans the width of the pit  78 . The baffle  90  is preferably a 3/16 inch thick belt comprised of 2-ply Dulon and 150# polyester. Baffle  90  is preferably of sufficient length to droop into the pit area  78 . The dump-side baffle  90  functions to control the airflow in the pit and induce a tumbling effect to the dust cloud caused by a dumping operation. The amount of time a dust cloud is retained in the pit is increased by making the cloud tumble, rather than naturally billowing straight up. Thus, the air intakes  70 ,  72  have more time to exhaust the dust cloud than if no dust cloud tumbling were provided. 
         [0064]    A grizzly  92  defines the bottom of the dumping pit  78 . A hopper  94 , as shown in  FIG. 1 , is disposed below the grizzly  92 . The grizzly  92  comprises a grid that screens impurities from the coal in car  69  that are larger than the aperture size in the grid. These impurities may include rocks and timber. The hopper  94  funnels the coal into a receiving pit, transport container or conveyor for transportation, storage or later use. 
         [0065]    The rotational frame  80  comprises a section of track  94  that is approximately the same length as a rail car  69 . The track  94  is sealed below, on the dump side and on the back side by plates  96  to prevent the escape of dust during a dumping operation. Each of the front  81  and back ends  83  of the rotational frame  80  are fastened to end plates  98  (shown in  FIG. 2 ). The end plates  98  are configured to permit the rotation of the frame  80  about an axis centered at the coupling of the rail car  69 , thereby permitting the cars  69  to remain coupled during a dumping operation. The rotational frame  80  receives a plurality of counterweights  100  to balance the car  69  and frame  80  during rotational motion. 
         [0066]    A plurality of frame baffles  102  are provided to the dump side  81  of rotational frame  80 . Referring to  FIGS. 3 ,  12 ,  13  and  15 , the baffles  102  are placed at multiple positions on the dump side of the rotational frame  80 .  FIG. 3  depicts three baffles  102  mounted to the frame  80  via hinged  103  fasteners. Such arrangement is shown with more detail in  FIG. 17 . The hinges  103  allow the baffles  102  to hang vertically regardless of the orientation of the rotational frame  80 , as shown in  FIGS. 3  though  8 . 
         [0067]      FIGS. 14 and 16  depict an alternative mounting configuration for the baffles  102 . An extension member  104  extends from the plate  96  to a fixed distance. The extension member is rigid. The baffle  102  is then fastened to the end of the extension member  104  via a hinged fastener  103 , as in  FIG. 17 , or by way of a fixed bracket  106 , as shown in  FIG. 14 . A further alternative involves fastening the fixed bracket  106  directly to the side of the frame  80  or plate  96  without an extension member  104 , as shown in  FIG. 16 . 
         [0068]      FIGS. 18   a  and  18   b  depict a baffle  102  according to a preferred embodiment. The baffle  102  comprises a top edge  108 , bottom edge  110 , first side edge  112 , second side edge  114 , two longitudinal side surfaces  116 ,  118  and leading edge  119 . The baffles  102  preferably extend the approximate length of the pit  78 , which is slightly longer than the length of a rail car  69 . Alternatively, a baffle  102  may comprise a series of baffle segments that, when operated as an assembly, are equivalent to a single baffle  102  spanning the approximate width of the pit  78 . 
         [0069]    Each baffle  102  is preferably fastened to a mounting bracket  106  by way of a plurality of threaded fasteners  107  extending through a respective plurality of apertures  120  in baffle. The apertures  120  communicate between the longitudinal surfaces  116 ,  118  of the baffle  102  and are equally spaced about a line adjacent the top  108  of the baffle  102 . A threaded bolt  132  is provided with a washer  134  (to minimize tearing through the aperture) to sandwich a portion of the baffle between the washer and a surface of the mounting bracket. The opposite surface of the bracket receives a locking washer (not shown) and threaded nut  136 . Those having skill in the art will recognize that other means for fastening the baffles  102  to the mounting brackets  106 , such as clamps and adhesives, may be used without departing from the spirit and scope of the present invention. The baffles  102  are preferable made from the same material as the dump-side hood baffle  90 . However, any flexible and rugged material may be used within the scope of the present invention. 
         [0070]    Referring to  FIGS. 3 through 8 , three baffles  102  are shown on rotational frame  80  throughout various points of a dumping cycle. Embodiments using fewer or greater numbers of baffles  102  are contemplated by the present invention. In.  FIG. 3 , the frame  80  is in a full upright position.  FIG. 4  shows the frame  80  rotated through approximately 60 degrees of motion. The first  122  of three baffles,  122 ,  124 , and  126 , is arched due to contact with the ski jump  84 . The length of each baffle  122 ,  124 ,  126  is preferably such that it will bow slightly, as shown in the figures, when contacting the upper surface  88  of the ski jump  84 . 
         [0071]      FIG. 5  shows the frame  80  at 90 degrees of rotation. Now, each of the first  122  and second  124  baffles are atop the ski jump  84 , thereby causing the baffles  122 ,  124  to bow. The contact between the upper surface  86  of the ski jump  84  and the leading edge  119  of the baffles  122 ,  124 ,  126  effectively bars the dust cloud from escaping out the backside of the dumping frame  80 . The cloud is sealed in the pit  78  until removed by the ducts  70 ,  72 . 
         [0072]      FIG. 6  shows the frame  80  at approximately 110 degrees of rotation. Now, only the second  124  of the baffles  122 ,  124 ,  126  is in contact with the ski jump  84 . This illustrates the point that, starting at approximately 60 degrees of rotation, one or more of the number of baffles  122 ,  124 ,  126  is in contact with the ski jump  84  to provide a seal on the backside of the frame  80 . 
         [0073]      FIG. 7  shows the frame  80  at approximately 130 degrees of rotation. Now, the third baffle  126  is in contact with the ski jump  84  and the first baffle  122  is completely past the jump  84 . The frame  80  continues its rotation until coming to 160 degrees of rotation as shown in  FIG. 8 . One hundred sixty degrees)(160° is a complete dumping motion for the depicted embodiment. Typically, the rail car  69  need not be rotated more than hundred sixty degrees) (160°) to achieve full dumping. 
         [0074]    The baffles  102  also provide the additional benefit of scraping the top surface  86  of the ski jump  84  with the leading edge  119  when the car  69  is rotated in the opposite direction. The scraping action shovels any accumulated dust off of surface  86 . This configuration results in a self-cleaning mechanism, which minimizes the need to periodically clean surfaces in the dump facility. 
         [0075]      FIGS. 9 ,  10  and  11  depict an alternative embodiment of the present invention wherein the rotary-dump facility  52  is configured to allow for a 180 degree dumping motion, while continuing to manage the airflow as previously discussed. These figures also illustrate that a counterclockwise direction dumping motion may be employed without departing from the spirit and scope of the present invention. Three baffles  122 ,  124 ,  126  are again shown as being hingedly fastened to the dump frame  80 . The second  124  and third  126  baffles are now disposed on protruding extension members  104 . A rigid airflow diverter member  127  is shown mounted in place of the hood baffle  90  to create the tumbling effect on the dust cloud within the pit  78 . 
         [0076]    The configuration of the ski jump  84  is modified with respect to that shown in  FIGS. 3-8  to accommodate the additional 20 degrees of rotation without structural interference between the ski jump  84  and the frame  80 . The sloped surface  86  of the ski jump  84  does not extend past the end of the backside hood  76  to provide the required clearance.  FIG. 9  shows that the upper surface  86  of the jump  84  no longer extends vertically above the backside hood  76 , as it did in  FIG. 3 .  FIGS. 9-11  show the frame  80  at 20°, 110° and 160°, respectively. The frame  80  may continue to rotate until reaching 180° without interference from the various dumping structures. 
         [0077]    Referring to  FIGS. 19 through 22 , various views of the rotary-dump facility  52  are shown to illustrate the hood  74 ,  76  and duct placements  70 ,  72  according to the preferred embodiment.  FIG. 19  shows a side sectional view of the dump side of the dump facility  52 . A plurality of dump side air intake ducts  70  branch off of the transfer duct  56 . Each branch  70  terminates in a hood  74 . The hoods  74  are approximately aligned with the top of the pit  78 . The hoods  74  span almost the entire distance between the end plates  98 . 
         [0078]    The operator station  128  is also shown in  FIG. 19 . The operator station  128  is generally placed above the dump side of the rotational frame  80  to provide the operator with a clear view of the pit area  78  and the grizzly  92 . This way, the operator may observe the dumping procedure to ensure safety and efficiency. Prior art systems that completely enclose the rail car  69  do not permit the operator to easily observe a dumping procedure. 
         [0079]      FIG. 20  shows a side sectional view of the backside of the dump facility  52 . A plurality of backside air intake ducts  72  branch off of the transfer duct  56 . Each branch terminates in a hood  76 . The hoods  76  are positioned near the bottom of the pit  78 . The relative positions of the dump-side  74  and backside  76  hoods may also be seen in  FIG. 3 . The hoods  76  span almost the entire distance between the end plates  98 . 
         [0080]      FIG. 21  shows a top partial sectional view of the dump side intakes  70  and respective hoods  74 . There are only relatively small gaps  138  between adjacent hoods  74 ,  76 . The minimal gaps  138  create a generally constant wall of suction to remove the dust cloud quickly.  FIG. 22  shows a top sectional view of the backside hoods  76 . The upper surface  86  of the ski jump  84  is outlined as a location reference. 
         [0081]    A major design goal for a dump-site  50  is to balance the system effectiveness with its efficiency. It is theoretically possible to remove a volume of air sufficient to dismiss the dust cloud without using any sealing systems. However, such systems would require enormous drive motors and would be undesirably inefficient. Therefore, it is a constant design goal to reduce the airflow to around 140,000 cubic feet per minute. The present invention provides a system and method that allows those design goals to be achieved in the preferred embodiments. To help achieve this goal, approximately 60 percent of the air volume is preferably removed from the backside duct system  72 . The remaining 40 percent is removed from the front or dump side  70 . The air duct hoods  74 ,  76  are spaced so as to achieve an even air distribution along the entire length of the dump frame  80 . 
         [0082]    Increasing the time the dust cloud is retained in the pit  78  allows a lower volume system to work effectively. Configuring the system as described herein and shown in the figures increases the retention time by tumbling the air below the dump frame  80  in the pit  78 . The tendency of the tumbling air is to remain in the sealed confines of the pit  78 , rather than seeking to escape. The baffles  102  and other features described herein contribute to this tumbling effect. 
         [0083]    Referring to  FIGS. 29   a ,  29   b  and  29   c , end of hood close off panel  222  includes arcuate shaped flat portion  228  and angled panel  230 . End of hood close off panel  222  is secured to platen support wall  224  by fasteners  232 . 
         [0084]    Referring to  FIGS. 30 and 31 ,  FIG. 30  depicts a rings out dumper facility  200 .  FIG. 31  depicts a rings in dumper facility  202 . Referring to  FIG. 30 , in a rings out dumper facility  200  supporting rings  204  are located at the far ends of the car dumper  206 . Referring to  FIG. 31 , in a rings in dumper facility  202  supporting rings  204  are located some distance inboard of the ends of car dumper  206 . 
         [0085]    Referring to  FIG. 23 , rings out dumper facility  200  generally includes support rings  204 , car dumper  206 , dumper platen  208 , supported rail car  210 , grizzly  212 , dual wheel trunion  214  and end ring baffle  216 . Support rings  204  support dumper platen  208  of car dumper  206 . Railcar  210  is supported by dumper platen  208 . Grizzly  212  is at the bottom of rings out dumper facility  200 . Grizzly  212  is a grating with openings through which dumped material may fall. Dual wheel trunion  214  supports supporting rings  204  thus, supporting car dumper  206  as it turns. 
         [0086]    Referring to  FIGS. 23-27 , end ring baffle  216  is located near to dumper pit wall  218  but inside of supporting ring  204 . End ring baffle  216  is attached to the end of and extends upwardly from grizzly  212 . End ring baffle  216  extends upwardly slightly beyond perimeter  220  of supporting ring  204 . The edge of end ring baffle  216  generally follows the perimeter  220  of supporting ring  204 . 
         [0087]    End ring baffle  216  is secured to grizzly  212  and caulked along its length to create a dust and air resistant shield. End ring baffle  216  is also secured to backside hood  76 . Referring to  FIGS. 24 and 26 , belting  226  may be utilized along the edge of backside hood  76  to seal backside hood  76  to supporting ring  204 . 
         [0088]    Referring particularly to  FIG. 27 , end ring baffle  216  is secured and sealed to the edge of grizzly  212 . 
         [0089]    Referring now to  FIGS. 28 ,  29   a ,  29   b , and  29   c , rings in dumper facility  202  generally includes car dumper  206 , dumper platen  208 , grizzly  212 , railcar  210 , and end of hood close off panel  222 . End of hood close off panel  222  extends from platen support wall  224  to backside diverter  84  (also known as the ski jump). End of hood close off panel  222  thus creates a barrier to prevent dust laden air from escaping the containment area. 
         [0090]    As baffles  102  rotate they first make contact with platen support wall  224  and then engages end of hood close off panel  222 . This arrangement creates a continuous seal for the remainder of rotation of the car dumper  206 , eliminating an escape path for dust laden air around the end of baffle  102 . 
         [0091]    In operation, a coal car  69  enters the rotary-dump facility  52  through entrance  130 . The car  69  may be coupled to adjacent cars with a rotary coupling. The car to be dumped  69  is indexed on to track  76 . The rotational frame  80  begins rotating the car  69  through a full dumping rotational motion of between 160 and 180 degrees, depending on facility design. As the car  69  is rotated, the material, such as coal, within the car  69  spills over the dump side of the car  69 . The car  69  exits the facility  52  through an exit  131  after dumping is completed and the car  69  is returned to its upright position. 
         [0092]    The dumping of the material generates a dust cloud. The cloud is retained in the pit  78  by sealing plates  96 ,  98  on the dump frame  80  and by the use of a plurality of baffles  102 . The baffles  102  and facility  52  design features, such as diverters  82 ,  84  hood baffle  90  and intake hoods  74 ,  76  cause the dust cloud to tumble within the pit  78 , thereby increasing the retention time of the dust cloud within the pit  78 . 
         [0093]    A plurality of intake hoods  74 ,  76  on both the dump side and back side of the frame  80  inhale the dust cloud and transmit the contaminated air through a transfer duct  56  to a remote filter facility  54 . The dirty air enters a lower portion  57  of the facility  54  and is passed through a filter assembly before arriving at an upper portion  55  of the facility  54 . The filter assembly traps the airborne contaminants in the lower portion  57  of the facility. The clean air continues through a filtered air exit duct  58 , through a fan housing  62  and exits to the atmosphere though a clean air exhaust duct  60 . 
         [0094]    In operation, end ring baffle  216  extends above grizzly  212  and beyond perimeter of supporting ring  204 . Thus, end ring baffle  216  seals off the space beneath supporting ring  204 , thus, preventing dust laden air from exiting dumping facility  252 . Thus dust laden air is retained in pit  78  until it can be removed by air flow. 
         [0095]    End of hood close off panel  222  creates a barrier between platen support wall  224  and backside diverter  84  thus blocking off a path of escape for dust laden air. End of hood close off panel  222  seals dust laden air in pit  78  until it can be removed by air flow. 
         [0096]    Although the present invention has been described with reference to the preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.