Air classification is
utilized to separate light materials from heavier materials through the use of
an air stream of sufficient velocity to carry away the lighter materials. This
machine is vital in the garbage sorting system to make the plant separate waste more
efficiently. A vertical zig zag air classifier with a rotating drum feeder will
be used in the MRF to separate aluminum, cartons and plastics from glass. The
feeder system uses a stationary drum with rotating blades that act as airlock
valves and a vertical feed hopper to deposit material into the drum. The
airlock valves allow the feeding system to take place in a confined space, providing
good energy efficiency. The vertical zig zag configuration has been shown to
enhance separation as a result of the pulsing of materials in and out of the
air stream that flows up the throat of the classifier, but at the expense of
increased jamming. A cyclone separator is used in conjunction with the air
classifier to remove the lighter separated fraction from the air stream after
it exits the classifier throat. The cyclone separator uses a centrifugal action
that results from the airflow through the cyclone to move the materials to the
walls of the separator. The materials then slide down the walls to the exit.
