Abstract:
A compact housing for a dedusting apparatus utilizes a magnetic flux field to disrupt the static charge attracting dust particles to product particles, which along with fluidization and counter current airflow principles that are proven to dislodge dust particles from the product, provides a highly efficient, compact deduster. The housing supports a double wash deck with product flow separated between the back-to-back primary wash decks. A deflector directing the flow of product onto the primary wash decks is provided with an extension that extends parallel to the wash deck to eliminated product bouncing off of the wash deck. The lower air outlets are eliminated, while the upper air outlets are positioned in extensions to the main housing above the product inlet opening. Air flow through the Venturi zones is enhanced by directing clean air through slots formed in the lower deck members into the Venturi zones.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 11/454,437, filed on Jun. 16, 2006, now issued as U.S. Pat. No. ______ on ______. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention disclosed in this application is directed generally to an apparatus for the cleaning and handling of particulate materials, such as plastic pellets, grains, glass, and the like, and particularly to the a low profile, compact apparatus that can be utilized in confined spaces without loss of efficiency. 
       BACKGROUND OF THE INVENTION 
       [0003]    It is well known, particularly in the field of transporting and using particulate materials, commonly powders, granules, pellets, and the like, that it is important to keep product particles as free as possible of contaminants. Particulates are usually transported within a facility where they are to be mixed, packaged or used in a pressurized tubular system that in reality produces a stream of material that behaves somewhat like a fluid. As these materials move through the pipes, considerable friction is generated not only among the particles themselves, but also between the tube walls and the particles in the stream. In turn, this friction results in the development of particle dust, broken particles, fluff, streamers (ribbon-like elements that can “grow” into quite long and tangled), glass fibers in glass filled products, that can impede the flow of materials or even totally block the flow. The characteristics of such a transport system are quite well known, as is the importance and value of keeping product particles as free as possible of contaminants. 
         [0004]    The term “contaminant” as used herein includes a broad range of foreign material and includes foreign material as well as broken particles or streamers of the product being transported. The generation of contaminants, also referred to as dust, can be from a large number of sources, including, in the way of examples, the creation of dust particles during the processing of plastic pellets in which the larger particles are segregated to be re-ground; organic matter in food grains, such as shells and hulls; the creation of dust in the formation of iron ore pellets; and, as noted previously, the mere conveyance of the pellets in pipes and other mechanical conveying and handling systems. Using plastics as an example, such foreign material could have a detrimental effect on the finished product. Specifically, foreign material different in composition from the primary material, such as dust, and non uniform material of the primary product, such as streamers, would not necessarily have the same melting temperatures as the primary product and would cause flaws when the plastics material is melted and molded. 
         [0005]    Considering product quality, and focusing on moldable plastics as a primary example, foreign material different in composition from the primary material, such as dust, non-uniform material of the primary product, fluff, and streamers, does not necessarily have the same melting temperatures as the primary product and causes flaws when the material is melted and molded. These flaws result in finished products that are not uniform in color, may contain bubbles, and often appear to be blemished or stained, and are, therefore, unsellable. It is important to note that since these same non-uniform materials often do not melt at the same temperature as the primary product, the unmelted contaminants cause friction and premature wear to the molding machines, resulting in downtime, lost production, reduced productivity, increased maintenance and thus increased overall production costs. 
         [0006]    Since dust and other contaminants are generated mostly by the transport system, it is of primary importance to not only provide apparatus for thoroughly cleaning the particles, but to do so as close to the point of use of the particles as possible so as to avoid the generation of contaminants through additional transport. Accordingly, compact dedusters have been used for many years to clean materials in this application, capable of handling smaller volumes of product, yet also capable of thoroughly cleaning the product. The compact dedusters permit the installation of the deduster immediately before final use of the products, such as being installed directly on top of molding machines or extruders, or on top of silos, as well as under silos, rather than at an earlier stage after which re-contamination can occur before the products are utilized. Of course, the dedusters can be installed as a free standing unit, as well. 
         [0007]    Dedusters used to clean contaminants from particulate material can be found in U.S. Pat. No. 5,035,331, granted to Jerome I. Paulson on Jul. 30, 1991, in which air is blown upwardly through wash decks over which a flow of contaminated particulate material is passed so that the flow of air up through the wash decks removes the contaminants from the material flow. A magnetic field is provided by the deduster so that the particulate material flow passes through the magnetic field to neutralize the static charge on the particulates and facilitate the removal of the contaminants from the material. The flow of contaminant laden air is discharged from the deduster, while the cleaned particulate material is passed on to the manufacturing process. 
         [0008]    A compact dedusting apparatus is disclosed in U.S. Pat. No. 6,595,369, granted on Jul. 22, 2003, to Jerome I. Paulson. Like the larger dedusting apparatus depicted in U.S. Pat. No. 5,035,331, the follow of particulate material is cleansed of contaminates that have had the static charged attracting the contaminates to the particulates neutralized. The cleaning process utilizes a flow of air passing through the stream of particulate material passing over wash decks. The contaminate-laden air is discharged through the top of the dedusting apparatus, while the cleaned particulate material is discharged from the bottom of the deduster. 
         [0009]    These compact dedusters are provided with a single wash deck bathed in a magnetic flux field to provide dual action cleaning that fluidizes the flow of particles over the wash deck and uses a counter current flow to dislodge dust particles from the product for discharge from the apparatus. The magnetic flux field extends on opposing sides of the magnetic flux field generator, as well as above and below the magnet. Accordingly, a single wash deck is utilizing only a quarter of the magnetic flux filed that is generated. Furthermore, a single wash deck is limited in capacity. A double wash deck configuration is known from the Pelletron Max Series dedusters, wherein back to back wash decks are provided with a lower dust air outlet having a deflector panel to minimize the inadvertent discharge of cleaned particles with the dust-laden air being discharged from the lower air outlets. 
         [0010]    The discharge of dust-laden air through the upper air discharge openings is a limiting factor to the capacity of the compact deduster to clean particles. If the velocity of the air passing through the wash decks and through the Venturi zone is too great, cleaned particles will be carried over into the discharged air flow. Thus, deflectors have been provided in an attempt to minimize product carryover and air velocity is closely controlled. The compact dedusters disclosed in the aforementioned Paulson patents represent a compact package in which highly efficient particle dedusting operations are conducted; however, some commercial or industrial applications for the dedusters require yet a smaller compact design, which exacerbates the aforementioned problems of capacity, carryover, and air velocity. 
         [0011]    Accordingly, it would be desirable to provide a dedusting apparatus that is more compact than previously known without sacrificing capacity and preferably improving cleaning efficiencies. 
       SUMMARY OF THE INVENTION 
       [0012]    It is an object of the invention to overcome the disadvantages of the prior art by providing a compact dedusting apparatus that has improved air flow characteristics for the inlet of clean air into the housing and the discharge of dirty air from the housing. 
         [0013]    It is another object of this invention to provide an effective compact dedusting apparatus that can thoroughly clean a flow of particulate material of dust particles and other contaminants immediately prior to the particulate material being used. 
         [0014]    It is still another object of this invention to provide an enhanced wash deck configuration to increase the capacity of a compact dedusting apparatus. 
         [0015]    It is an advantage of this invention that the size of the housing of the compact deduster is reduced, while increasing the capacity of the unit by using a higher loading of particulates through the Venturi zone. 
         [0016]    It is a feature of this invention that the air outlets are positioned in extensions to the main housing. 
         [0017]    It is another advantage of this invention that the distance from the wash decks to the air outlet openings are established to minimize product carryover without deflector panels. 
         [0018]    It is another feature of this invention that a double wash deck configuration is utilized to increase operating capacities. 
         [0019]    It is still another advantage of this invention that the double wash deck does not require a lower air outlet. 
         [0020]    It is yet another feature of this invention that the flow of air through the Venturi zone is enhanced 
         [0021]    It is still another feature of this invention that the inlet air path is directed from the back of the housing to the backside of the Venturi panel. 
         [0022]    It is yet another advantage of this invention that the by-pass box on the sides of the deduster housing can be eliminated to further minimize the size of the deduster housing. 
         [0023]    It is a further feature of this invention that air slots are installed in the underside of the split wash deck to increase air flow in the Venturi zone. 
         [0024]    It is a further advantage of this invention that granular materials with heavy dust contamination can be cleaned efficiently. 
         [0025]    It is still a further feature of this invention that the inlet deflector directing the flow of product onto the primary wash decks includes a portion of the deflector panel oriented parallel to the wash decks. 
         [0026]    It is still a further advantage of this invention that the deflector smoothes the flow of product onto the primary wash deck by eliminating the bouncing of the product particles off the primary wash deck. 
         [0027]    It is a further object of this invention to enhance the flow of air into the Venturi zone by directing a flow of air through the lower deck members. 
         [0028]    It is still another feature of this invention that the lower deck members are formed with a plurality of slots that direct air through the lower deck members into the adjacent Venturi zone. 
         [0029]    It is still another advantage of this invention that the slots formed in the lower deck members enhance the flow of air into the Venturi zone and reduces the likelihood of dead air spots within the Venturi zone adjacent the first wash decks. 
         [0030]    It is a further object of this invention to provide a compact dedusting apparatus with improved air flow and a double wash deck to enhance capacity, which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
         [0031]    These and other objects, features and advantages are accomplished according to the instant invention by providing a compact housing for a dedusting apparatus utilizing a magnetic flux field to disrupt the static charge attracting dust particles to product particles, which along with fluidization and counter current airflow principles that are proven to dislodge dust particles from the product, provides a highly efficient, compact deduster. The housing supports a double wash deck with product flow separated between the back-to-back primary wash decks. A deflector directing the flow of product onto the primary wash decks is provided with an extension that extends parallel to the wash deck to eliminated product bouncing off of the wash deck. The lower air outlets are eliminated, while the upper air outlets are positioned in extensions to the main housing above the product inlet opening. Air flow through the Venturi zone is enhanced by directing clean air through slots formed in the lower deck members into the Venturi zones. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
           [0033]      FIG. 1  is a front elevational view of a compact dedusting apparatus incorporating the principles of the instant invention, the magnetic coil being shown in phantom; 
           [0034]      FIG. 2  is a side elevational view of the compact dedusting apparatus depicted in  FIG. 1 ; 
           [0035]      FIG. 3  is a top plan view of the compact dedusting apparatus depicted in  FIG. 1 ; 
           [0036]      FIG. 4  is a partial front elevational view of the compact dedusting apparatus showing the arrangement of the wash decks and Venturi zones for cleaning dust particles from a flow of product over the wash decks; 
           [0037]      FIG. 5  is a side elevational view of the housing for the compact dedusting apparatus reflecting the division of the sections for the clean air, dusty air and cleansing operations; 
           [0038]      FIG. 6  is a top plan view of the housing depicted in  FIGS. 4 and 5  showing the discharge path of the dusty air and the inlet of the dirty product; 
           [0039]      FIG. 7  is a front elevational view of the compact dedusting apparatus with the wash decks removed to better view the flow path of clean air inputted into the housing; 
           [0040]      FIG. 8  is a side elevational view of the housing corresponding to  FIG. 7  to better view the clean air flow path and the dusty air flow path through the housing; 
           [0041]      FIG. 9  is a top plan view of the housing depicted in  FIG. 8 ; 
           [0042]      FIG. 10  is a detail view of the inclined surface of the first wash deck; 
           [0043]      FIG. 11  is a detail view of the inclined surface of the second wash deck; 
           [0044]      FIG. 12  is a partial cross-sectional view of the slots in the wash decks corresponding to lines  12 - 12  of  FIG. 11 ; 
           [0045]      FIG. 13  is a partial side elevational view of the first wash deck assembly to show the configuration thereof; and 
           [0046]      FIG. 14  is a partial schematic front elevational view of the first and second wash deck assemblies to show air flow into the Venturi zone. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0047]    The dedusting apparatus is known in the art. A description of the structure and operation of a dedusting apparatus and a compact dedusting apparatus can be found in U.S. Pat. No. 5,035,331 and in U.S. Pat. No. 6,595,369, both of which were issued to Jerome I. Paulson, the contents of each of these patents being incorporated herein by reference. Typical particulate material to be cleaned by the dedusting apparatus  10  is plastic pellets that are to be passed into an injection molding machine to form plastic components. Examples of plastic particulate material that can be cleaned of contaminate material by the dedusting apparatus  10  are polyester, acrylic, high density polyethylene, polypropylene, nylon, polycarbonates, styrene, and low density polyethylene. Other types of particulate material that can be cleaned in the dedusting apparatus  10  include glass particles and grain. 
         [0048]    Referring to  FIGS. 1-9 , the dedusting apparatus  10  is connected to a vertical portion of a fluent material handling system (not shown) such that the particulate material is fed into a product inlet port  30  located at the top of an airtight casing  11 . The casing  11  has two subcomponents, a main housing  15  in which the wash decks apparatus  50 , as described below, is mounted, and an air flow passageway  16  primarily located behind the main housing  15 . The product inlet port  30  is in flow communication with the main housing  15  to direct product particulates onto the first wash deck  52  for cleaning. A magnetic coil  31  generating a flux field is mounted at the inlet port  30  so that the flow of particulate material into the housing  15  to be cleaned is subjected to the magnetic flux field to neutralize the static charges on the particulate pellets, thus making the separation of the contaminates from the pellets easier to accomplish. Air is fed into the casing  11  through a clean air inlet port  20  located in the lower part of the back of the casing  11 . As will be described in greater detail below, the air is distributed through from the clean air plenum  18  through internal passages to a first inlet opening  22  below the first wash decks  52  and to a second inlet opening  24  below the second wash decks  55 . 
         [0049]    The casing  11  is formed with a back panel  12 , in which the clean air inlet port  20  and the dusty air discharge port  25  are located, and integral side, top and bottom panels that form a generally rectangular configuration. A removable front door  13  is connected to the remainder of the casing  11  by fasteners  13   a  to permit access into the wash deck apparatus  50  for service and maintenance thereof. An interior panel  14  oriented parallel to the back panel  12  and the front door  14  divides the casing  11  into a main housing  15  situated between the interior panel  14  and the front door  13  and an air flow passageway  16  situated between the back panel  12  and the interior panel  14 . A separator panel  17  divides the air flow passageway into a lower clean air plenum  18  and an upper dusty air plenum  19 , each of which being in flow communication with the respective clean air port  20  and the dusty air port  25 . 
         [0050]    The configuration of the wash deck apparatus  50  is in a double set, oriented back-to-back such that the first wash decks  52  are angled downwardly at an incline of approximately 30 degrees from the horizontal in opposing transverse directions. The second wash decks  55  are positioned beneath the first wash decks  52  so as to receive the flow of product particles therefrom, as will be described in greater detail below, and convey the product over an inclined surface that is also oriented at about a 30 degree incline relative to the horizontal. The first wash decks  52  are formed in a central diamond-shaped assembly that includes a lower deck member  54  associated with each of the first wash decks  52  and connected thereto by a generally vertically extending portion  53 . The lower deck members  54  help define an air flow path that directs air transversely outwardly into Venturi zones  35  through which air is directed in a counter current flow to aggressively remove dust particles from the product. 
         [0051]    Product to be cleaned is introduced into the housing  15  through the product inlet opening  30  at the center of the top portion of the housing  15 . The magnetic coil  31  is positioned around the product inlet port  30  to introduce a magnetic flux field which covers the entire housing  15 . Since the product flow needs to be divided equally between the back-to-back first wash decks  52 , a divider  32  is positioned to split equally the product flow into two opposing transverse directions onto the first wash decks  52 . A product inlet deflector  40  is positioned at the product inlet opening  30  on opposite sides of the divider  32  to direct the product inflow uniformly over the respective first wash decks  52 . Each product inlet deflector  40  includes an inwardly directed member  42  that deflects the product toward the divider  32  to be spread evenly across the longitudinal width of the first wash deck  52 . A vertical portion  43  connects the inwardly directed member  42  with an angled portion  45  that serves as an anti-jump device to prevent product particles that impact directly onto the wash deck  52  from bouncing off the deck  52  and heading upwardly toward the dusty air discharge opening  28 . The anti-jump extension  45  thus reduces product carryover into the discharge of dusty air from the housing  15 . 
         [0052]    As can best be seen in  FIGS. 10-12 , the first air wash deck  52  and the second air wash deck  55  have a patterned array of holes  57  and slots  58 , the holes  57  creating jets of air, which are directed substantially vertically through the product layer flowing over the wash decks  52 ,  55 , causing the dust and streamers on the particulate product to be entrained in the air flow and be driven upwardly away from the particulate product. The slots  58  in the first air wash deck  52  provide a ribbon or sheet of air which accelerates the particulate product forwardly along the product path over the first air wash deck  52  toward the second wash deck  55 , moving the individual particles at a speed greater than their terminal velocity. This increased velocity of the product permits use of higher counter current air velocity in the Venturi zone  35  resulting in improved cleaning efficiency. 
         [0053]    The second air wash deck  55  is supported by the housing  15  in a downwardly directed incline opposite to that of the first air wash deck  52 , though also oriented at a minimum angle of 30 degrees to the horizontal. In other words, the second wash decks  55  are angled from both opposing sides to direct a flow of product particles toward the center where the product discharge port  34  is located. Pressurized air is introduced into the second air wash deck  55  from the second inlet openings  24  in the interior panel  14  located beneath the second wash decks  55  to pass upwardly through the second air wash deck  55  similarly to that described above with respect to the first air wash deck  52  to clean any remaining contaminates from the flow of particulate product directed onto the second air wash deck  55 . 
         [0054]    The product particles moving off of the first wash deck  52  may have sufficient velocity, particularly due to the velocity boost generated by the ribbon of air passing through the slots  58 , that the product particles may impact a generally vertical deflector plate  36  defining the outboard sides of the Venturi zones  35 . Product deflected off of the deflector plates  36  are directed downwardly to the second air wash decks  55 . The product discharge port  34  is provided at the center of the housing  15  between the two second wash decks  55  to receive product from the second wash decks  55  for discharge from the housing  15 . 
         [0055]    Air entering through the second inlet opening  24  is also directed behind the deflector plates  36 , through an air flow chamber  39  that is in flow communication with the clean air plenum  18  beneath the second air wash decks  55 , for use in adjusting the air flow in the Venturi zones  35 . The air flow chamber  39  extends rearwardly into the clean air plenum  18  rearwardly of the interior panel  14  to deliver air above the second wash decks  55  and behind the deflector plates  36 . The adjustment mechanism  38  is connected to each respective deflector plate  36  which is pivotally mounted about the longitudinally extending pivot  37  so that the bottom of each deflector plate  36  is movable into the corresponding Venturi zone  35  to permit a flow of air past the bottom of the deflector plates  36  into the Venturi zones  35  to increase the air flow through the Venturi zones  35 . The air flow through the wash decks  52 ,  55  and through the Venturi zones  35  is directed upwardly toward the dusty air outlet openings  28 . 
         [0056]    To boost the air flow through the Venturi zone  35  and to minimize any dead air spots within the Venturi zone  35 , the lower deck members  54  are provided with three to four rows of slots  59  that are oriented to blow air through the lower deck members  54  from the first clean air inlet opening  22  and into the Venturi zones  35  to boost the air flow and provide an even distribution of the air flow through the Venturi zones  35 . The loss of air through the slots  59  in the lower deck members  54  does not detract significantly to the performance of the air washing of particulate material passing over the first deck  52 . 
         [0057]    Higher velocity of air moving through the Venturi zones  35  results in a greater counter current flow cleaning action to remove dust particles from the product. The higher the velocity of the air is, the greater the chance of product particles being trapped in the air flow and being carried up to the dusty air discharge opening  28 . The vertical distance between the first wash deck  52  and the dusty air discharge opening  28  needs to be as large as possible, which is counter to the design goal of providing a compact deduster apparatus  10 . Accordingly, the casing  11  is formed with a pair of extensions  27  located on opposing ends of the casing  11  that project above the rectangular casing  11  into which the dusty air discharge openings  28  are formed. The extensions  27  are in flow communication with the main housing  15  to allow dusty air to flow upwardly through the dusty air discharge openings  28  into the extensions  27  then rearwardly and then downwardly behind the main housing  15  into the dusty air plenum  19  forming the upper portion of the passageways  16  to reach the dusty air discharge port  25  at the back of the casing  11 . 
         [0058]    As shown in  FIGS. 1 and 7 , the extensions  27  include a baffle  29  that elevates the opening  28  above the top of the main housing  11 . Since the velocity of the dusty air decreases with the extended vertical height of the discharge opening  28 , the likelihood of product carryover through the discharge opening  28  is reduced as the heavier particles will not rise to the elevated discharge opening  28 . 
         [0059]    By directing the clean air from the inlet port  20  into the clean air plenum  18 , air can be introduced under pressure to the first air wash decks  52  through the first inlet opening  22  centrally located within the diamond-shaped wash deck configuration below the first wash decks  52 , and to the second wash decks  55  through laterally spaced second air inlet openings  24  positioned beneath the second wash decks  55 , as is indicated by air flow arrows  61 - 63  in  FIGS. 7-9 . The portion of the clean air plenum  18  below the second wash decks  55  extends upwardly behind the deflector plates  36  to add air flow into the Venturi zones  35  as needed through adjustment of the pivoted deflector plates  36 . This arrangement of the clean air plenum  18  eliminates the need to have a by-pass box mounted on the side of the casing  11  to direct air flow into the Venturi zones  35 . 
         [0060]    The dusty air discharge path, represented by air flow arrows  64  in  FIGS. 7-9 , passes into housing extensions  27  positioned at the outside top corners of the casing  11  to provide a dusty air discharge opening  28  in the main housing  15  that is separated sufficiently from the first wash decks  52  to prevent product carryover, especially with respect to smaller product particulates within the product flow through the apparatus  10 . The utilization of the housing extensions  27  enable the casing  11  to maintain a lower profile, as the housing extensions  27  are positioned above the casing  11 , above the product inlet opening  34  into the main housing  15 , and laterally of the magnetic coil  31 , but below the mounting flange  33  that connects the apparatus  10  to the external line delivering product to the apparatus  10 . Thus, the dusty air flow path, represented by the air flow arrows  64 , exits the main housing  15  through a discharge opening  28  at the opposing upper, outboard extremities thereof, then upwardly and rearwardly through the housing extensions  27 , and then back down into the dusty air plenum  19  for discharge from the casing  11  through the port  25 . 
         [0061]    In operation, the dedusting apparatus  10  receives a volume of contaminated particulate material to be cleaned which is introduced into the product inlet port  30 . The particulate material passes through the magnetic flux field generated by magnetic coil  31  to disrupt the static charge attraction causing the contaminates to adhere to the individual particles of the particulate material. Material flow control is important in order to cause particulate particles to disperse in such a way that air can flow freely through the product stream so as to lift contaminants upward away from the product. The flow of material through the dedusting apparatus  10  is controlled by the inlet deflector members  40  and divided into laterally opposing flow paths by the divider  32  to drop onto the first air wash decks  52 . Preferably, the product inlet deflectors  40  and the divider  32  are positionally adjustable to optimize the flow characteristics of the particulate material being fed into the apparatus  10 . 
         [0062]    If the layer of particulate material on the first air wash deck  52  is too thick, air may prevented from passing efficiently through the particulate material to separate out the contaminates. If the layer of particulate material is too thin, the air flow will not be efficiently utilized. The divider  32  must be also positioned properly to divide the product flows to the opposing first air wash decks  52 . If one side of the wash deck apparatus  50  gets overloaded, as compared to the opposite side, the air flow through the wash deck apparatus  50  will seek the path of least resistance and move away from the overloaded side of the wash deck apparatus  50 , thus reducing the cleaning operation of the apparatus  10 . 
         [0063]    Pressurized air flows through the holes in first air wash deck  52  to separate the contaminates from the individual pellets of product material, the contaminate particles being smaller and lighter than the product particulates. The air flow through slots  58  accelerates the partially cleaned product toward deflector plate  36 . This partially cleaned particulate product then passes from the first wash decks  52  toward the corresponding second wash decks  55  and passes through a higher velocity counter air flow in the Venturi zones  35  passing upwardly on each opposing side of the wash deck apparatus  50  from the second air wash deck  55 , and through the lower deck members  54 , through the narrowed opening between the vertical member  53  of the first air wash desk  52  and the deflector plate  36 . The particulate product then falls onto the second air wash decks  55  for a further separation of contaminates from the particulate product. The lower deck members  54  direct the air passing through the second air wash decks  55  and the layer of particulate material thereon into the respective Venturi zones  35  as defined above. Lower dusty air discharge openings are not utilized, and thus special air deflector members are not necessary to prevent product carryover from the second air wash decks  55 , to increase the air flow through the respective Venturi zones  35 . 
         [0064]    The first air wash deck  52  separates small particles of 100 microns and less from the flow of particulate material thereon. The Venturi zones  35  (between the first air wash decks  52  and the deflector plates  36 ), when adjusted correctly, will remove larger contaminants, thereby providing a two stage separation of contaminants as large as 1/52 of an inch. The particulate material is then passed across the second air wash deck  55  with residual contaminates being separated at this time. Finally, the cleaned product drops to the bottom of the main housing  15  and is discharged out of the dedusting apparatus  10  through the product outlet port  34 . 
         [0065]    Because of the different characteristics of the various products that can be introduced into the apparatus  10  to be cleaned of dust particles, certain aspects of the apparatus are made adjustable, as is generally known in the art. For example, the positions of the product inlet deflectors  40  and the divider  32  are preferably positionally adjustable to evenly and equally distribute product flows to the opposing air wash decks  52 ,  55 . The deflector plates  36  forming the outboard sides of the respective Venturi zones  35  are preferably positionally adjustable so as to both change the physical dimensions of the Venturi zones  35 , which alone changes the velocity of the air flowing through the Venturi zones  35 , but also adds air flow past the deflector plates  36  into the Venturi zones  35 . Too much air and too great of a velocity for some products will increase the product carryover into the dusty air discharge openings. Under typical operating circumstances, the preferable pressure differential between the Venturi zones  35  and the dusty air discharge openings  28  is equal to about five inches of water. 
         [0066]    A clean air adjustment valve  21  is provided at the top of the clean air plenum  18  to control the volume and pressure of the clean air flow being introduced into the apparatus  10  through the clean air inlet port  20 . Similarly, air bleed out disks  24   a  are provided in the clean air plenum  18  below the second air wash decks  55  to control the air flow through the second wash decks  55  and the air flow available to the Venturi zones  35  from behind the deflector plates  36 . 
         [0067]    It will be understood that changes in the details, materials, steps and arrangements of parts, which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles of the scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description may be employed in other embodiments without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly, as well as in the specific form shown.