Processing plastic for recycling

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Discussion Overview

The discussion revolves around the design and construction of machines for processing plastic items, specifically focusing on small-scale agglomeration techniques for plastic films. Participants explore the feasibility, safety, and environmental implications of such methods, as well as alternative approaches to densifying plastic.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • The original poster (OP) seeks to build a small-scale agglomerator for plastic films, noting that such machines are prevalent in China and India but not elsewhere, possibly due to high power consumption and weight.
  • Some participants express concerns about the health risks associated with processing hot plastic, suggesting that a solid understanding of the chemistry of plastics is necessary before proceeding.
  • One participant questions the claim that such methods are banned in Australia and asks for evidence, while also inquiring about alternative methods for densifying plastic film.
  • Another participant emphasizes that DIY recycling methods are not advisable by 'western' standards and raises concerns about emissions and wastewater management in small-scale operations.
  • Concerns are raised about the mixing of different plastics and the challenges of sorting them effectively at a small scale, suggesting that compacting without proper sorting could lead to waste issues.

Areas of Agreement / Disagreement

Participants express differing views on the viability and safety of DIY plastic processing methods. While some caution against proceeding without adequate knowledge, others advocate for exploring alternative methods. The discussion remains unresolved regarding the safety and practicality of the proposed agglomeration technique.

Contextual Notes

Limitations include the lack of consensus on the safety of processing plastics at home, the need for proper sorting and handling of different types of plastics, and concerns about emissions and wastewater management that may not be fully addressed in small-scale operations.

d-Wizz
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TL;DR
Advice for building specialised small-scale machinery to assist with recycling various plastic items.
[Mentor Note: link to OP's blog website deleted]

I need to learn where to find someone who will work with me to design and build machines for processing various plastic items. The end result will be granulated plastic, but the journey there will be different according to the physical and mechanical properties of the material being processed.

In summary, I am looking at building a small-scale agglomerator for plastic films. Research thus far seems to suggest that these machines are commonly used in China and India but nowhere else. The power consumption in the tens of kW may be one reason and the size and weight (1,000 kg) may be another. I want to investigate whether the concept is viable on a smaller scale such that domestic electricity (10A, 240V) can be used.

The basic concept is that a drum with blades on the bottom and on the sides rotates at very high speed. When plastic film is placed inside the drum, the friction generates sufficient heat to densify the plastic. The blades prevent the material from becoming one large lump. Apparently, at a certain stage, a cup of cold water is introduced into the drum. The plastic immediately solidifies and the blades chop it up. The result is said to resemble "plastic popcorn".
 
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Welcome to PF.

I don't know much about the subject matter, but here is a link to a local startup company here in Silicon Valley that is bringing AI and more robotics to the field of Recycling. Maybe have a look at their website and contact them if it looks like there may be some synergy with your efforts. Good luck.

https://www.everestlabs.ai/
 
d-Wizz said:
Research thus far seems to suggest that these machines are commonly used in China and India but nowhere else.
Erm... There is a reason for that.

Plenty of DIY-level 'recycling' methods gone viral on youtube and such (yes, many of them from India and China - kind of sad to see some done with 'western' machinery), but you should know that the reason they are banned to there is that hot plastic can very easily become really, really, seriously unhealthy.

Without having a solid knowledge about chemistry of plastics I recommend you to abandon this idea.
 
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Rive said:
Without having a solid knowledge about chemistry of plastics I recommend you to abandon this idea.
I would be interested to receive your evidence for this being "banned" in Australia.

Would you therefore suggest an alternative method for densifying plastic film? I've been using a sandwich press for 4 years and it's tedious and very labour-intensive. Agglomeration seemed like a much faster and efficient method.

Fumes are not a problem with adequate ventilation or extraction system. That's the #1 reason I do not work with PVC.
 

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d-Wizz said:
Would you therefore suggest an alternative method for densifying plastic film?
Nope.
By 'western' standards, this is just no to be done DIY.
Waste is for the (selective) waste bins.

d-Wizz said:
Fumes are not a problem with adequate ventilation or extraction system.
The place I live still about stoves for the winter.
Stoves has 'adequate ventilation'.
Still, when it's winter, the air quality is often terrible.
This is due two reasons.
- some financially less blessed people burns anything what can be acquired and can be burned
- stoves having ventilation, not filtering...

In short, emission is also a problem. Just ventilation is far from enough.

Regarding the attachment you (?) removed... There was two points you can/should seriously consider.
- the wastewater of washing is also a concern, and to properly address that it's best to have bigger plants for processing
- there was that line about the different melting point of different plastics, and the result of mixing them... At small scale you cannot expect consistent sorting.

Ps.: regarding that 'compacting'... Actually, before (DIY) compacting plastic waste is proper for sorting. After 'compacting' it's unknown waste -> landfill :confused: I really do hope I took that part about the sandwich press wrong...
 

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