Densification
process
Plastic
wastes which are coming as packaging films, fibers and foams have lower
density. So previously mentioned cutting or crushing methods can’t use for those
wastes to size reduction. Because of the lower density many problems can arise while
transporting, conveying, and feeding. In this method density is increased by
using agglomeration process.
Generally
there are three main methods are used to do agglomeration by densifying disks, by
compression, and by agitation.
 |
| densifying disks |
- Densifying disks
Mostly
films which are made up from PP, LDPE, HDPE and fibres made from polyamides are
converting in to granulate form using this method. In here plastic is slightly heated
by friction disks and densification is happen without happening thermal
degradation.
- By compression
In this method compression is used to extrude
plastic and form pellets continuously. Compressed material is coming out through
a die and it is chopped using a rotary cutter.
- By agitation
In this
method waste plastic is vigorously agitated causing the plastic material to agglomerate
in to densified particles. This is happening because high shear generated by
rotating blades brings plastic to a near melting state.
Advantages
of densification are reduced storage volume, reduced the transporting cost,
improved flow properties etc.
Pulverization
processes
 |
| pulverization mill |
Pulverization
mills like disk mills and pin mills are used in this method for converting plastic
waste in to fine powder. Recycle polymer powders including sintered powder
coatings, molding powders, fillers are produced using this method.
Mainly
this method is used for size reduction of PVC. After pulverization that powder
has high bulk density, excellent flow characteristics, and homogeneous composition.
