compression_VS_densification
There are two main options to recycle EPS scrap. One way is to use heat (thermal densification) and the other way is without heating (compression). Compression involves crushing and compacting EPS by machine. The compacted materials are extruded into a solid ‘log’. The log is cut to length to fit onto a pellet. It is usual for the densified EPS to be stored on-site until 5 to 20 metric tones are available, as this makes transport and distribution more cost-effective. The more densely compacted the EPS is, the better, since a higher weight of EPS can be loaded for transport and a higher price per tone may be paid by the recycler. Compression can reduce EPS volume by up to forty times.
Thermal densification involves breaking up and melting EPS inside a controlled-temperature chamber. The temperature is controlled to allow the EPS to melt without burning. Higher compression ratios (up to 95% volume reduction) can be achieved using the melting method that involves heating the expanded polystyrene to a very high temperature to compress the product. The disadvantage of this method is that it involved a hot element that needed to remain powered throughout the day, and this proved to be very energy inefficient and posed safety hazards due to the off-gassing of chemicals. On-and-off operation of the machine can be a big waste of energy and time because of cooling and re-heating of the machine.
