Polyethylene
Polyethylene Recycling
Polyethylene is a thermoplastic homopolymer used in a vast array of applications due to its variable crystalline structure. With approximately 10 million tonnes produced each year, PE is one of the most used polymers in the world today. Polyethylene is produced in various forms depending on its’ intended use; including, but not limited to: LDPE, LLDPE, HDPE and UHMW.
Recycling polyethylene can not only be extremely lucrative if done correctly, but is also one of the most simple and energy-efficient to reprocess. Despite this, there is still huge opportunity for the recycling industry to gain financially, as vast quantities are still landfilled each year. To see how Rotajet machines recycle polyethylene, take a look at the overview of the process shown below.
The Polyethylene Recycling Process
Shredding
Pre-Washing
Separation
Granulation
Drying
Bagging off
Shredder– In typical situations, a shredder is used for the initial size reduction of the material. The feed stock is normally reduced down to a shred of 40-50mm.
RJ-PWS-75 – The material is fed from the hopper into the Rotajet pre-washer to remove the majority of the contamination. This efficient incline plastic washer is fitted with inline filtration and automatic chemical dosing.
RJ-HKS-50 – A Rotajet sink-float is then used to separate the polyethylene from contaminants such as ABS, PVC, PET, glass, metals and others. The sinking fraction is screwed to bagging off for disposal whilst the floating fraction is transferred into the next stage.
RJ-GR – This powerful wet granulator ensures an even particle size so your final product is suitable for resale into the market. Durable and efficient, our granulators are completely welded and have a heavy steel construction, making them capable of withstanding the most demanding requirements present in the industry.
RJ-MD-55 – This horizontal mechanical dryer is the most efficient way of dewatering granulated and shredded plastics. Our mechanical dryers can reduce moisture levels for rigid plastics down to around 1%. The machine is fitted with a rotor which rotates at high speed (approx. 1450rpm). To ensure our dryers are simple to maintain, the rotor is fitted with easy-to-change wear paddles manufactured from D2 steel.
RJ-DB-ZZ – Finally, a zig-zag separator is used to remove any remaining fines, ensuring a product quality suitable for extrusion
Polyethylene - Explained
Polyethylene is the most commonly used type of plastic which, due to its variable crystalline structure, can be adapted to suit a broad range of purposes. The two most common examples of Polyethylene variations are the thermoplastic polymers High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE); both of which are made from the monomer ethylene.
LDPE - Low Density Polyethylene
In comparison to HDPE, LDPE is a low density plastic that is often not recycled. It’s flexible material and propensity to stretch make it ideal for various but specific plastic packing demands.
Common uses for LDPE include:
- Film wrap (cling film)
- Bubble wrap
- Plastic shopping bags
- Cereal packets
- Bread bags
Recycling LDPE has historically been demanding and complex due to its lightweight and flexible properties requiring a large amount of space. On top of this, the structure of LDPE makes it susceptible to getting caught in recycling machinery; thus leading to machine downtime and costly repairs. In recent years, however, the development of specially-designed machinery such as Rotajet’s range of recycling equipment has allowed the recycling of LDPE to be simple and hassle-free.
These solutions to recycling LDPE make for an extremely lucrative and environmentally-friendly alternative to landfilling. As well as the complex demands of LDPE, Rotajet’s Recycling Machinery is built to withstand the even the most unique demands of HDPE, PET, PVC, PP, PS among other plastic types
HDPE - High Density Polyethylene
HDPE is a type of plastic resin that is often used in plastic packaging to make various bottles. The unique thermophysical properties of HDPE make it highly dense and strong; and therefore desirable for use in plastic packaging. Compared to LDPE, HDPE is much more stiff, strong, and reliable due to its highly condensed molecular structure: therefore making it ideal for producing more demanding plastic packaging items.
HDPE is often used to make:
- Shampoo bottles
- Plastic bags
- Detergent bottles
- Milk bottle
HDPE plastic packaging is commonly collected from households by curbside recycling programs, with around 30% of the material being recycled. With its characteristic inability to withstand autoclaving, HDPE is a highly economical material for recycling, and as a result is consistently the most recycled type of plastic year on year.
The ease of recycling HDPE partnered with its high demand within the plastic packaging industry, makes it an extremely simple and lucrative process. Rotajet’s full range of recycling machinery can help to manage this process, with very little operator input and with an optimised use of resources; therefore helping to keep operational costs down whilst ensuring the highest possible high profit margin.
Contact Rotajet
We aim to get back to any enquiry within 12 hours, so please do contact us if you are interested in a specific machine or would like to discuss a cleaning requirement. Our friendly team are happy to help with email info@rotajet.co.uk or call +44 (0) 1924 271446.