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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Patent Application No. 61/178,651 filed on May 15, 2009 in the U.S. Patent Trademark Office, the disclosure of which is incorporated herein in its entirety by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Apparatuses and methods consistent with the present invention relate to a rock dusting apparatus for distributing rock dust, aggregate or other materials. 
         [0004]    2. Description of the Related Art 
         [0005]    The present invention involves an apparatus and method for distributing rock dust particularly for use in the underground coal mining industry. However, the apparatus may be used to distribute other materials. 
         [0006]    The accumulation of coal dust common in underground mines can lead to dangerous explosions. To minimize this risk, rock dust is distributed to the face and floor of the mine to reduce the accumulation of coal dust. While mechanical rock dusters are used to apply the rock dust, the machines in existence today require constant attention during operation as well as a large amount of maintenance. Additionally, the known machines are not easily transportable. 
         [0007]    Further, some of these machines use highly pressurized air, which may lead unsafe conditions. As such, the tanks containing this highly pressurized air require pressure relief valves to prevent a catastrophic failure of the tank due to the highly pressurized air. These additional mechanical parts add to the cost and maintenance requirements of the machine. 
         [0008]    Thus, there exists a need for an improved rock dusting apparatus that solves the maintenance and portability problems. 
       SUMMARY OF THE INVENTION 
       [0009]    Exemplary embodiments of the present invention address at least the above problems and/or disadvantages and other disadvantages not described above. Also, the present invention is not required to overcome the disadvantages described above, and an exemplary embodiment of the present invention may not overcome any of the problems described above. 
         [0010]    The present invention provides a more efficient way of distributing rock dust particularly for use in underground coal mines. However, this apparatus is not limited to the distribution of rock dust. One of ordinary skill will understand that the present invention may be utilized for the distribution of other types of aggregate and particulate matter. 
         [0011]    According to an exemplary aspect of the present invention, there is provided a rock duster including a cylindrical tank body having an inlet portion and an outlet portion, the inlet portion disposed toward a bottom end of the cylindrical tank and the outlet portion disposed toward an top end of the cylindrical tank; an air supply unit connected to the inlet portion of the tank to supply air, wherein the inlet portion injects the air in a substantially circumferential direction with respect to an axis of the cylindrical tank body. The tank body may include a circular top member removably attached to a top of the cylindrical tank body. 
         [0012]    The inlet portion may include a circular member disposed at a bottom of the cylindrical tank, the circular member containing a plurality of nozzles directed to inject the air in the substantially circumferential direction. Each of the plurality of nozzles may include an air flow orifice. The plurality of nozzles may be spaced circumferentially from one another, radially spaced from one another, or a combination of both. The circular member may include an agitator attached to the circular member. 
         [0013]    According to another exemplary aspect of the invention, the rock dusting apparatus includes a cylindrical tank body having an air inlet and an outlet portion, the air inlet disposed toward a bottom portion of the cylindrical tank and the outlet portion disposed in a top portion of the cylindrical tank; a top member removably attached to a top of the cylindrical tank body and configured to releasably seal the top of the cylindrical tank body; a bottom member attached to a bottom of the cylindrical tank body and configured to seal the bottom of the cylindrical tank body; an air supply unit connected to air inlet to supply air to the bottom portion of the cylindrical tank body; and a circular member disposed within the cylindrical tank body between the top member and the bottom member to divide the cylindrical tank body into the top portion and the bottom portion, the circular member is configured to inject air from the bottom portion into the top portion in a substantially circumferential direction with respect to an axis of the cylindrical tank body. 
         [0014]    Each of the plurality of nozzles may include an air flow orifice. The plurality of nozzles may be spaced circumferentially from one another, radially spaced from one another, or a combination of both. The circular member may include an agitator attached to the circular member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The above and/or other aspects of the present invention will be more apparent by describing certain exemplary embodiments of the present invention with reference to the accompanying drawings, in which: 
           [0016]      FIG. 1A  is a side view of the tank illustrating a rock dusting apparatus according to an exemplary embodiment&#39; 
           [0017]      FIG. 1B  is a top view of the inlet portion of  FIG. 1A ; 
           [0018]      FIG. 2  is a side view of a rock dusting apparatus according to another exemplary embodiment; 
           [0019]      FIG. 3A  shows the air distributor of the embodiment of  FIG. 2 ; 
           [0020]      FIG. 3B  is a side view air distributor of  FIG. 3A ; 
           [0021]      FIG. 4  shows a rock dusting system according to an exemplary embodiment; 
           [0022]      FIG. 5  shows the regenerative blow of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0023]    Certain exemplary embodiments of the present invention will now be described in greater detail with reference to the accompanying drawings. 
         [0024]    In the following description, same drawing reference numerals are used for the same elements even in different drawings. The matters defined in the description, such as detailed construction and elements, are provided to assist in a comprehensive understanding of the invention. Thus, it is apparent that the present invention can be carried out without those specifically defined matters. Also, well-known functions or constructions are not described in detail since they would obscure the invention with unnecessary detail. 
         [0025]      FIG. 1A  shows configuration of a first exemplary embodiment of the present invention. The cylindrical tank body  100  is generally oriented such that its cylindrical axis  140  extends vertically. However, this orientation is not necessary and the cylindrical axis may be arranged toward a horizontal position. However, for the purposes of the description below, assume the cylindrical axis is vertically oriented. 
         [0026]    The cylindrical tank body  100  is generally cylindrical in shape and forms a substantially sealed container with the exception of the inlet portion  110  and the outlet portion  120 . The top member is  150  removably secured to the cylindrical tank body  100  and removed for the purpose of filling the body with aggregate. 
         [0027]    An air supply source provides pressurized air to the inlet portion  110  disposed at the bottom of the cylindrical tank body  100 . The air is distributed into the cylindrical tank body  100  using a plurality of nozzles  160 . As shown in  FIG. 1B , the nozzles  160  direct the pressurized air  170  into a substantially circumferential air flow  130  with respect to the cylindrical axis  140 . This air flow creates a vortex effect within the cylindrical tank body  100  capable mixing some of the aggregate disposed within the cylindrical tank body  100  with the air to carry the aggregate and air mixture to the outlet portion  120 . This velocity component of the air (vortex) permits aggregate to be effectively dispersed within the cylindrical tank body  100  without requiring excessive air pressure. The air and aggregate mixture exits the outlet portion  120  to be dispersed where desired. 
         [0028]    One aspect of the present embodiment is the use of a regenerative blow  221 , which is also known as a ring compressor. While other air sources may be used, the ring compressor provides a relative low pressure, high volume air flow. 
         [0029]    The nozzles  160  may be configured as holes within plate metal having a directional component or as holes extending along the cylindrical axis that have directing nozzle portions attached thereto. These directing nozzle portions may be directed to distribute the air in the circumferential direction. 
         [0030]    As illustrated in  FIG. 1B , the nozzles  160  may be circumferentially spaced from one another around the inlet portion. The nozzles  160  may also be spaced radially from one another. In this embodiment, the nozzles  160  are spaced circumferentially at two different radial positions. 
         [0031]    While the shape of the cylindrical tank body  100  is described as cylindrical in this exemplary embodiment, other shapes may be used. 
         [0032]      FIG. 2  shows a partial sectional view of sealable tank  207  used in the rock duster apparatus. The sealable tank includes a tank lid  2099 , a side member  214  and a bottom member  213 . The side member  214 , the tank lid  209  and the bottom member  213  are connected to each other to form an air-tight seal. To facilitate removal of the tank lid  209 , the sealable tank  207  may also include a lid locking lever ring  208  for removably securing and sealing the tank lid  209 . The removable tank lid  209  facilitates loading of the sealable tank  207  with rock dust, aggregate, or other particulate matter for distribution. 
         [0033]    An air distributor  201  is disposed above the bottom member  213  of dividing the sealable tank  207  into a loading portion  215  and an air expansion chamber  205 . The air expansion chamber  205  is positioned below the loading portion  215 . The sealable tank  207  also includes an inlet port  206  for supplying pressurized air to the expansion chamber  205 . The inlet port  206  may be provided with a control value to control the rate at which the apparatus dispenses the particulate matter. The air from the air expansion chamber  205  is distributed to the loading portion  215 , which is loaded with rock dust or other particulate matter to be blow with the air through the outlet  210 . The air is distributed using a mass air distributor  201  which distributes the pressurized air so as to induce a vortex in the loading portion  215  of the sealable tank  207 . Delivering the air in this manner efficiently uses the energy of the pressurized air to carry the rock dust or other particulate matter to the tank outlet  210  for distribution. 
         [0034]    As shown in  FIGS. 2 ,  3 A and  3 B, according to this exemplary embodiment, the mass air distributor  201  may include multiple intake ports  204  that distribute air from the air expansion chamber  205  to the upper portion  215  of the tank body  212 . The intake ports  204  are provided at various locations on the mass air distributor  201  to induce a vortex air flow in the loading portion  215 . The intake portions  204  are disposed in a direction so as to direct the air to induce a circumferential circulation of air in the upper portion  212  of the sealable tank  207 . This air flow creates a vortex effect within the upper portion  212  of the sealable tank  207 . Accordingly, the air attains a suitable velocity enabling it to carrying the rock dust or other particulate matter toward the tank outlet  210 . In this embodiment, the sealable tank  207  is substantially cylindrical to aid in inducing this vortex air circulation. However, other tank shapes may be used. 
         [0035]    These intake ports  204  may be directed substantially circumferentially with respect to the center of the tank  207  to aid in directing the air flow to create a vortex. The intake ports  204  may also include air flow orifices  203  to aid in directing the air flow and controlling the amount of air flow. The orifices may be configured to convert the static air pressure of the air in the expansion chamber  205  into air velocity, thereby reducing the static air pressure in the upper portion. Thus, by controlling the velocity of air in this fashion, a vortex of relatively low pressure air may carry the rock dust or particulate to the tank outlet  210 . 
         [0036]    Also, as shown in  FIG. 2 , the sealable tank  207  may include an agitator to aid in dislodging the rock dust or other aggregate from the surface of the mass air distributor  201 . In the configuration of  FIG. 2 , this agitator causes vibration as air from the air expansion chamber  205  passes through an air powered agitator  202  attached to the mass air distributor  201 . 
         [0037]    Operationally, the pressurized air  170  is introduced through the inlet port  206  and enters the air expansion chamber  205 . The pressurized air then passes through the mass air distributor  201  through the intake ports  204  and air flow orifices  203 , air also passes through the air powered agitator  202 , which is used to facilitate the mixing of the air and rock dust. 
         [0038]    The air stream which is now in a vortex motion created by the mass air distributor  201 , mixes with the dust or aggregate and rises up to the top of tank  207 . This rising mixture is then captured by the air directing plate  211 , which directs the mixed air and rock dust through the outlet  210  for distribution. 
         [0039]      FIGS. 4 and 5  show a rock dusting system according to another exemplary embodiment of the present invention. This air supply system is shown in combination with the exemplary embodiment of  FIG. 2 , but can also be applied to the exemplary embodiment of  FIG. 1 . 
         [0040]    The regenerative blower and tank assembly of  FIG. 4  shows regenerative blower  221  coupled to a sealable tank  207  using an inlet port  206 . The air supply system includes an inlet filter  222  disposed on the inlet port  216  of the regenerative blower  221 . An outlet relief value  223  is disposed on the outlet port  217  of regenerative blower  221  to prevent excessive back pressure from damaging the regenerative blower  221 . A hose  224  transfers the pressurized air from the regenerative blower  221  to an air moisture separator  225 . The air moisture separator  225  is not required but may aid in the distribution of aggregate or other particulate matter whose physical properties are negatively impacted by moisture. As illustrated in  FIG. 4 , the pressurized air leaving the moisture separator  225  enters the inlet port  206  of the sealable tank  207 . If used in the exemplary embodiment of  FIG. 1 , a distribution manifold may be utilized to distribute the air to each nozzle. 
         [0041]    The system includes a motor starter  228  connected to the regenerative blower  221  by an electric cable  229 . 
         [0042]    As shown in  FIG. 5 , the regenerative blower  FIG. 3  may include an electric motor  218 , an enclosed fan assembly  220 , a mounting plate  219 , and inlet port  216  and an outlet port  217 . The regenerative blower  221  pulls air into the inlet port  216  and pushes air through the outlet port  217  at a predetermined volume or CFM to supply the rock duster apparatus. 
         [0043]    In operation, the lid locking lever  208  and lid  209  are removed. Rock dust or other aggregate is placed into tank  207 . The lid  209  is replaced and locking lever ring  208  is engaged. The motor starter  228  is electrically connected, such as by using an electric extension cord. The motor starter  228  is engaged and the rock dust is distributed. 
         [0044]    In another embodiment shown in  FIGS. 6-8 , the shape of the mass air distributor  301  may be modified into a concave shape. This mass air distributor  301  may be used in combination with the other features of tank  207  discussed in  FIGS. 1-5 . This concave shape improves the ability of the apparatus to induce vortex/tornado effect within the sealable tank  207  and aids in eliminating dead zones where material is not blown from the tank during normal operation. As shown in the figures, the air flow orifices  303  are disposed on intake ports  304  positioned at multiple locations along the surface of the mass air distributor  301  to distribute air from the air expansion chamber  205  to the upper portion  212  of the sealable tank  207 . An air powered agitator  202  may also be disposed in the center of the mass air distributor  301 . 
         [0045]    Testing has shown that the apparatus effectively emits rock dust when using approximately 0.625 cfm per 1 pound of dust per hour when the air pressure is less than 5 psi. However, in the embodiments shown above, the air pressure supplied to the tank may range from 3 to 8 psi. For example, to distribute 250 lbs of rock dust over an 8 hour period, a 2 hp ring air compressor at 150 cfm may be used. 
         [0046]    However, air flow requirements will change with the particulate or aggregate to be dispersed using the apparatus described above. The apparatus is not limited to rock dust distribution and may be used to distribute seed, fertilizer or any other particular requiring dispersion. 
         [0047]    Although a few exemplary embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

Summary:
A rock dusting or aggregate distributing apparatus is provided having a cylindrical tank body connected to an air supply unit. A circular member is disposed within the cylindrical tank body between the top member and the bottom member to divide the cylindrical tank body into a top portion and bottom portion, the circular member is configured to inject air from the bottom portion into the top portion in a substantially circumferential direction with respect to an axis of the cylindrical tank body to disperse rock dust or aggregate.