Apparatus for comminuting waste materials

Apparatus for comminuting waste material into pieces having a size less than a predetermined size, comprising:

• a frame having an enclosure with an entrance opening for receiving the waste material;
• a set of overlapping scissor rolls rotatably mounted on the frame for shearing the waste material into smaller pieces as the material is passed between the scissor rolls;
• feed means for recieving the material from the entrance and directing the material between the scissor rolls;
• a screen mounted on the frame within the enclosure downstream of the scissor rolls for permitting undersized smaller pieces of a size less than the predetermined size to pass therethrough and for preventing oversized smaller pieces of a size greater than the predetermined size from passing therethrough;
• a recycle conveying means movably mounted on the frame within the enclosure for directing the smaller pieces over the screen and for recycling the oversized smaller pieces back to the feed means;
• drive means operatively connected to the scissor rolls and the conveying means for rotating the scissor rolls to shear the material into progressively smaller pieces during each pass of the material between the scissor rolls and for moving the conveying means to direct the smaller pieces over the screen to permit the undersized smaller pieces to pass through the screen and to continually recycle the oversized smaller pieces back to the feed means until the smaller pieces are reduced to undersized small pieces;
• and
• vacuum means for drawing air into the enclosure to form an air current and drawing the air current through the screen to entrain the undersized pieces passing through the screen therein and conveying the undersized pieces from the enclosure.