Apparatus for segregating foreign matter from smokable material

Abstract

Particles of non-smokable material are segregated from a flow of a mixture of smokable and non-smokable materials by subjecting the flow to a first segregating treatment which divides the flow into a first stream consisting practically exclusively of smokable material, and a second stream constituting a relatively small percentage of the flow and containing substantially all of the non-smokable material and the remnant of smokable material. The second stream is treated for a second time, preferably at the discharge end of a pneumatic conveyor system including at least one conduit, to segregate the non-smokable material from the remnant of smokable material which latter can be admitted to the first stream. The segregating device which divides the flow into the first and second streams is or can be utilized to treat the second stream, i.e., to segregate smokable material of the second stream from the non-smokable material of the second stream.

1 . Apparatus for segregating foreign matter which is randomly distributed in a flow of comminuted smokable material, comprising: 
 means for advancing the flow in a predetermined direction along a first path;    means for subdividing the flow, in a predetermined portion of said path, into a first stream which is at least substantially devoid of foreign matter and a second stream which contains at least a major part of foreign matter and is at least likely to contain some smokable material; and    means for pneumatically reintroducing, along a second path, at least some of the second stream into said first path upstream of said predetermined portion of said first path.    
   
   
       2 . The apparatus of  claim 1 , wherein said reintroducing means comprises at least one tubular conveyor.  
   
   
       3 . The apparatus of  claim 1 , further comprising means for collecting the second stream downstream of said subdividing means, as seen in said predetermined direction, and means for segregating at least some foreign matter from said second path prior to reintroduction of at least some of said second stream into said first path.  
   
   
       4 . The apparatus of  claim 3  for segregating relatively heavy foreign matter from lighter material, wherein said segregating means includes means for receiving the relatively heavy foreign matter by gravity flow and said reintroducing means includes a suction-operated gathering device for lighter material at said collecting means.  
   
   
       5 . The apparatus of  claim 4 , further comprising a conveyor extending at least substantially transversely of said predetermined direction downstream of said subdividing means and arranged to collect and advance the second stream, said conveyor having a discharge end at said segregating means.  
   
   
       6 . The apparatus of  claim 5 , wherein said discharge end is disposed at a level above said segregating means.  
   
   
       7 . The apparatus of  claim 5 , wherein said conveyor is an endless conveyor.  
   
   
       8 . The apparatus of  claim 4 , wherein said gathering device is arranged to draw lighter material from said second stream at said collecting means.  
   
   
       9 . The apparatus of  claim 8 , wherein said gathering device is disposed at a level above said segregating means.  
   
   
       10 . The apparatus of  claim 1 , further comprising a conveyor extending at least substantially transversely of said predetermined direction downstream of said subdividing means and arranged to collect the second stream.  
   
   
       11 . The apparatus of  claim 10 , wherein said conveyor is arranged to deliver the second stream to said reintroducing means.  
   
   
       12 . The apparatus of  claim 10 , wherein said conveyor includes an endless belt conveyor.  
   
   
       13 . The apparatus of  claim 1 , wherein said advancing means comprises a vibratory trough and an endless belt conveyor arranged to receive the flow from said trough.  
   
   
       14 . The apparatus of  claim 1 , wherein said advancing means comprises a track arranged to convey said at least some of the second stream to said subdividing means, said reintroducing means having an outlet arranged to discharge said at least some of said second stream into said track.  
   
   
       15 . The apparatus of  claim 14 , wherein said track includes a partition between said advancing means for the flow and said at least some of said second stream.  
   
   
       16 . The apparatus of  claim 14 , further comprising a receptacle arranged to receive said at least some of the second stream from said outlet of said reintroducing means.  
   
   
       17 . The apparatus of  claim 16 , wherein said receptacle has an open top for reception of at least some of the second stream.