Abstract:
A sifting apparatus for stratifying raw material includes a material feed-in device, a material support unit, a gas plenum, and a discharge control device. The material support unit receives material from the material feed-in device and has a surface having a plurality of openings for a gaseous medium introduced from underneath the material support unit, thereby effecting loosening and stratification of the material into a layer of relatively heavier material, and a layer of relatively lighter material atop the heavier material. The introduced gaseous medium originates in a pump, is collected in a pressurized reservoir and is controlled by a metered valve prior to introduction to the material support unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of U.S. Provisional Patent Application No. 62/051,184, filed Sep. 16, 2014, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    This disclosure relates generally to a sifting apparatus and, more specifically, to a sifting apparatus for preparatory concentration of raw materials including, e.g., raw coal. 
       BACKGROUND 
       [0003]    Sifting or settling apparatuses generally include a material feed device, material support unit with holes through which flows a gaseous fluid, often gas guided by a plenum disposed underneath the material support unit, and a discharge control device for controlling separated discharge of relatively heavier material and relatively lighter material. The inflowing pulsed gas operating to loosen the material fed onto the material support unit stratifies the material into layers of relatively lighter material atop of layers of relatively heavier material. An air sifting apparatus of this type is described, for example, in the publication Schubert “Aufbereitung fester mineralischer Rohstoffe”, Band II VEB Deutscher Verlag fuer Grundstoffindustrie, Leipzig, Pages 89 and 90. 
         [0004]    Typically, sifting apparatuses, like the one described above, produce a less distinct separation between the heavier and lighter materials when compared with wet sifting machines. To achieve satisfactory sorting results according to the aforementioned apparatus, traditionally multiple factors must be present including, for example, a large density difference between the components of the material. There is always a need for an improved sifting apparatus. 
       SUMMARY 
       [0005]    Sifting apparatuses (“jigs”), whether wet or dry, operate according to two functions: they stratify and then separate. Improved stratification can be achieved when the volume, acceleration, and pulse frequency of the gas or air used in the jigging stroke are each achieved with relative independence. The inclusion of a pressurized reservoir has not been utilized in dry jigging, and thus rapid decompression of the gaseous medium occurs in the gas plenum after each jigging stroke. This disclosure provides a sifting apparatus that offers a solution to the challenge of providing a jig in which the acceleration of the jigging stroke can be improved without excessive pressure loss in the plenum or at the pump discharge point and without deleterious flow change across the material support unit. Stratification can be achieved, and thus the separation will be enhanced, while shock to the pumping device is reduced. 
         [0006]    The solution to this challenge is principally comprised of providing a reservoir or at least one reservoir of sufficient size to accept gaseous flow from a pump to build a pressure and relatively large volume that will permit discharge of pulses of relatively smaller volumes as a controlled valve opens and closes, thereby causing flow of gas into the plenum, whereupon the pulsating gas flow is adjusted to a pulse strength sufficient to lift the particles of the material upward and, via the consequent varying distance of fall, thereby effect stratification of the material into relatively heavier material layers and relatively lighter material layers. 
         [0007]    One embodiment includes a sifting apparatus having a material support unit having a base with one or more apertures located therethrough; a plenum attached to an underside of the material support unit of e.g., a gravity separator; a gas or air dispenser that is attached to the plenum and in communication with the material support unit, and that provides a pulsating gaseous medium flow to the material support unit; a pump in communication with the dispenser, wherein the pump provides a pressurized medium; a reservoir that maintains a threshold pressure and that is positioned between the pump and the dispenser; and a discharge control in communication with the material support unit and operable to control discharge of a relatively heavier material. 
         [0008]    In accordance with embodiments of the jig, the pressure of the pulsating gas flow can also be adjusted by the proper selection of a pump, which will pressurize the reservoir. 
         [0009]    Additional features and advantages of the present disclosure are described below. This disclosure may be readily utilized as a basis for modifying or designing other structures, systems, and processes for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent implementations do not depart from the teachings of the disclosure as set forth in the appended claims. The novel features, which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages, will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The particular features and advantages of the present disclosure will be apparent from the detailed description set forth below in conjunction with the drawings in which like reference characters identify corresponding aspects throughout. 
           [0011]      FIG. 1  is a schematic side view of embodiments of a sifting apparatus of the present disclosure having a reservoir; and 
           [0012]      FIG. 2  is a flow diagram of embodiments of using the sifting apparatus of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    As shown in  FIG. 1 , a sifting apparatus or jig  100  may include a pressure build up system including a pump  102  and reservoir  104 , a pressure release unit including an adjustable orifice  106  and meter  108 , a plenum  110 , a material support unit  112 , a discharge control  114 , a light product discharge channel  116 , a heavy product discharge channel  118 , a dust collection housing  120 , and a material feed-in unit  122 . As can be seen from  FIG. 1 , the arrangement of the pump  102 , the plenum  110 , and the reservoir  104  may be connected to or incorporated into other traditional gravity separators (e.g., having features such as, a material support unit  112 , a light product discharge channel  116 , a heavy product discharge channel  118 , a dust collection housing  120 , and a material feed-in unit  122 ). 
         [0014]    The pump  102 , which assists in producing a gas or air flow to the remainder of the jig  100 , may deliver gas or air at a relatively constant pressure to the reservoir  104 , for example. This embodiment may extend the life of the jig  100  due to the structure of the jig  100  reducing the vacillation of pressure from intermittent flow of gas through the meter  108 . However, other embodiments may include variable or intermittent pressure being produced in the reservoir  104  by the pump  102 . 
         [0015]    The reservoir  104  stores air or gas supplied by the pump  102  and may have a pressure relief valve located thereon (not illustrated) for releasing excess pressure at or above a desired threshold. Such desired pressure threshold of the pressure release valve may be set by a user or may be determined according to the reservoir&#39;s  104  properties and capacity, for example. As illustrated, the reservoir  104  may be ovular in shape. However, the reservoir  104  may have any shape, size, and volume without deviating from the scope of the present disclosure. In further embodiments, the reservoir  104  may have a volume sufficient to reduce significant pressure drops in the reservoir when a relatively smaller volume of air or gas is released to the rest of the jig  100 . 
         [0016]    The adjustable orifice  106  allows for the flow of air or gas to the plenum  110  from the reservoir  104  and pump  102  to be controlled and adjusted. There can be a control to maintain the pressure above the material support unit to be plus or minus 2″ water gauge, which is essentially neutral with atmospheric pressure. Also, a seal on the light material discharge or a gaslock similar to a star gate can be utilized to assist this. The adjustable orifice  106  may be any device capable of adjusting and regulating gas flow (frequency of discharge and volume of gas) and may be controlled by various means such as electronically, wirelessly, Bluetooth, or direct user contact, for example. Proximate to the adjustable orifice  106  may be a metering device  108  capable of measuring flow pressure or rate of the gas being released to the plenum  110 , thereby allowing for the control of the frequency and volume of pulsations into the gas plenum  110 . The metering device  108  may have outputs such as analog, digital, and audible, for example. Further, such outputs may be directly communicated to a user or may be indirectly communicated to a user through a computer. By providing relatively independent control of volume, pressure (i.e., acceleration of flow), and frequency of pulse using the meter  108  and the adjustable orifice  106 , stratification and control of stratification of material on the material support unit  112  is enhanced. By producing enhanced stratification, the separation of relatively heavy material (e.g., iron) from relatively light material (e.g., coal) is also enhanced, thereby producing a more efficient jig  100 . 
         [0017]    The plenum  110  is in fluidic communication with the reservoir  104 . As illustrated, the plenum  110  may have a conical shape, with a greater surface area located at the top of the plenum  110  and a smaller surface area located at the bottom of the plenum  110 . However, the plenum  110  may have any shape or size without deviating from the scope of the present disclosure. Attached to the bottom of the plenum  110  may be the heavy product discharge channel  118 . However, it should be appreciated that the heavy product discharge channel  118  may be located anywhere upon the plenum  110 , or on the material support unit, or adjacent to the material support unit, where the lighter material cannot pass upon being stratified. 
         [0018]    Also attached to the plenum  110  is the material support unit  112  that provides support for the heavy and light material mixture waiting to be stratified. A surface area upon which the material mixture is supported may include a plate or screen having holes there through. The material support unit  112  may be made of any material capable of supporting the material mixture, such as wood, metal, metal alloy, plastic, or any other material, for example. The material support unit  112  may also have any shape sufficient to encompass the material mixture. In one embodiment, the material support unit  112  may have a shape substantially similar, or identical, to that of the corresponding area of the plenum  110  upon which it couples. In other embodiments, the material support unit  112  may have a shape independent of the shape of the plenum  110 . 
         [0019]    The material support unit  112  also enhances the stratification of the material mixture buy using movements such as rotation and pulsation, for example. The movement of the material support unit  112  may be provided by various means, including electronic, wireless, Bluetooth, or direct consumer contact, for example. The stratification of the material mixture is aided by a gaseous medium flow provided by the reservoir  104  and pump  102 . In an embodiment, a pulsating gaseous medium flow provided to the mixture material periodically lifts the material to promote stratification of the mixture into a heavy material layer and a lighter material layer located atop the heavy material layer without significantly segregating or separating the materials toward the ends or sides of the material support unit  112 . In a further embodiment, the plenum  110  may produce a more constant gas flow through the openings of the material support unit  112  along with a pulsating air gas flow, overlaid on the constant air flow, the pulse impacting the material mixture on the material support unit  112 . As illustrated, the material support unit device  112  may be located at an angle within the jig  100 . In other embodiments, the material support unit  112  may be oriented at different angles and orientations from that depicted in  FIG. 1 , including being directly or substantially horizontal, for example. 
         [0020]    As illustrated, the light product discharge channel  116  is attached to the material support unit  112 . However, it should be appreciated that the light product discharge channel  116  may be attached to the exterior of the plenum  110  at an area downstream from the material support unit  112  and in an area where the heavy material cannot access. Located proximate to the material support unit  112  and the light product discharge channel  116  is the discharge control device  114 . The discharge control device  114  allows for the adjustable selection or control of heavy material capable of passing through the discharge control device  114  and the light product discharge channel  116 . The discharge control device  114  may be controlled by any sufficient means, such as electronically, wirelessly, Bluetooth, or by direct user contact, for example. Further, the discharge control device  114  may include devices capable of determining densities of material, such as a nuclear sensor, X-ray sensor, optical sensor, or any other sensor capable of determining densities, for example. The discharge control device  114  may also include a device capable of determining thicknesses of material, such as, for example, a mechanical sensor. The discharge control device  114  may also be configured to direct the heavy material to a location separate from the light product discharge channel  116 , such as the heavy product discharge channel  118 . In an embodiment, the discharge control device  114  may include a device capable of automatically controlling discharge of the heavy material. 
         [0021]    A dust collection housing  120 , which manages the amount of dust released by the jig  100 , may be attached to the material support unit  112  by fasteners such as screws, clamps, snaps, epoxies, resins, and seals, for example. Specific embodiment of the system may or may not have a dust collector. The dust collection housing  120  may be conical in shape, as illustrated in  FIG. 1 , or may be any other shape sufficient to trap dust. 
         [0022]    A material feed-in device  122  may be proximate to the material support unit  112 , and also may be proximate to the dust collection housing  120 . In a further embodiment, the material feed-in device may be removably attached to the dust collection housing  120 . The material feed-in device provides for replenishment of the material mixture to the material support unit  112 . In so doing, the material feed-in device  122  may provide the material mixture in uniform or substantially uniform dosages, or may also provide the material variably. Such manner of replenishment may be calculated according to volume, density, or weight of the material mixture, for example. In yet another embodiment, the material feed-in device  122  may include a volume adjustment device. 
         [0023]    As seen in  FIG. 2 , a method  200  of using a jig according to the present disclosure is depicted. At block  202  the material support unit is supplied with a material mixture containing at least one relatively heavier material and at least one relatively lighter material. This supplying of the material mixture may occur directly or may occur through the use of a material feed-in. Supplying of the material mixture may occur at a uniform rate or may occur in variable dosages based on, for example, volume, density, and/or mass of the material mixture. 
         [0024]    At block  204  pressure is generated in the reservoir by using the pump. The pressure generated in the pump may be set by a user of the jig, or may be determined based on the physical characteristics of the reservoir and pumping power of the pump. At block  206  the material mixture located on the material support unit may be stratified. Such stratification may occur through the use of movements such as rotation, pulsation, and/or vibration of the material support unit, for example. At block  208  gas may be released from the reservoir to the material support unit. Such release of gas may be constant, or variable, or intermittent. 
         [0025]    In one embodiment, the release of gas from the reservoir may include releasing the entirety of the pressure, built up in the reservoir, all at once. In other embodiments of the present disclosure, the gas stored in the reservoir may be released gradually so that there always remains some pressure buildup within the reservoir. In yet another embodiment, the release of pressure from the reservoir may include releasing a constant gas flow along with a pulsating gas flow overlaid on the constant gas flow, for pulses to impact the material mixture on the material support unit. 
         [0026]    In the operation and use, the sifting apparatus or arrangement may operate similar to other sifting apparatuses (e.g., a gravity separator) or with other sifting apparatuses. Material to be handled is fed onto a support device e.g., through a funnel, which can perform the dosing preparation of the material. Gas or air introduced constantly flows upwardly through the support device from below so as to effect a base fluidization which contributes to a loosening of the material layer lying on the material support device. The loosened material layer exhibits a reduced resistance than would be exhibited by a material layer on the material bed support device which had not been subjected to a constant air or gas flow. As a result of this sifting movement, the layers of the material bed sort themselves into the relatively heavier material layer and the relatively lighter material layer. 
         [0027]    The present disclosure is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.