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distinguish between plastic and glass

large_ghostman

Well-Known Member
Most Helpful Member
#21
As. Said above, CleanRobotics.com does just that, image processing, and separating conveyors to identify cans (whole, crouched, ...) from plastic bottles (whole, partially full, crushed) from cups, or even a half of a hamburger. Each is sorted into organic waste, aluminum, steel, or plastics bins. All happens in fraction of a second.

It may not be a great (optimal) use of energy and recycling (their trash bins are actually in stadiums, convention centers and malls), but they have made plenty of cash by translating their vision system software into other sorting automation projects.
I missed that part of the post, its an interesting area of science with these vision systems, my drone used the vision system lib from labview to avoid obstacles. This was 3-4 years ago maybe two i cant remember :D, but the latest open source ones are on a whole other level! Really cool tech but with a potentially sinister side. Also as cell phones get better quality cameras on them, it starts to really open up the possibilities.

Take milk bottles in the UK, alot of people dont know that the plastic cap is different from the milk bottle, if you wash the bottle out and stick the cap back on, then throw it in the recycle bin. The chances are that milk bottle will not get recycled because the cap would need to be separated. We cant be far away from a phone app that scans your stuff for recycling, it could flag up things like this before you put it in your recycle box for the local authority to come and collect it.

It would make a big difference here to true recycle rates. Sorry i missed the stadium bit, its got me thinking :D.
 

large_ghostman

Well-Known Member
Most Helpful Member
#22
BTW gophert would you mind pm ing me your email address? I would like to share something with you for an opinion on it. Its EG related, also did you have much to do with PEG?
 

camerart

Active Member
#23
Hi,
As mentioned there is a problem with the flotation method, unless the materials are ground down.
I would think some kind of ringing test, where the glass would ring higher. Perhaps a vibrating table or high freuqency speaker.
Best of luck, Camerart.
 
Last edited:

unclejed613

Well-Known Member
#24
this is a bit of a tough one. i was going to say measure the dielectric constant, but "plastics" of various types and various formulations of glass all have dielectric constants in the same range of 2 to 10. there's a lot of overlap between plastics and glasses and their dielectric properties. there may be an RF absorption characteristic that you could find, where a particular frequency gets absorbed by a silicate molecule, but not by polymers.
 

gophert

Active Member
#25
this is a bit of a tough one. i was going to say measure the dielectric constant, but "plastics" of various types and various formulations of glass all have dielectric constants in the same range of 2 to 10. there's a lot of overlap between plastics and glasses and their dielectric properties. there may be an RF absorption characteristic that you could find, where a particular frequency gets absorbed by a silicate molecule, but not by polymers.
Unfortunately, silica is a common additive for paints (like the bumper facia on your car). And Mica (a silicate mineral) is a common filler for polypropylene used in automotive parts. Talc (another silicate mineral) is used in ABS and Polycarbonate. Good luck.

Stop focusing on electronics - the density of glass is about 2x or more of plastics. Mill them to powders/small pieces and use Air classifying (wind sifting). Or just dump it all into a landfill (if wind sifting talks more energy than the fuel value of the plastic less incremental transport cost.
 

JimB

Super Moderator
Most Helpful Member
#26
Or just dump it all into a landfill
Woah! Hold that thought right there!

You cannot say things like that.
You will have our little eco warrior (LLG) on your tail for saying things like that.

He will go on to explain how this confirms the low standards that the USA has in these areas.

JimB
 

gophert

Active Member
#27
Woah! Hold that thought right there!

You cannot say things like that.
You will have our little eco warrior (LLG) on your tail for saying things like that.

He will go on to explain how this confirms the low standards that the USA has in these areas.

JimB
I'll take that challenge. Some communities / countries spend more on the back end trying to recycle than the fuel value of the material. There is virtually no use for recycled plastics vs the quantity produced so burning is the only logical option. If you use more fuel to assemble all the plastic to a single power generation station, then it is a useless effort (since nearly all costs are energy.

Communities would be much better off banning one-time use plastic items (bags, packaging, straws, etc).
 

JimB

Super Moderator
Most Helpful Member
#28
Communities would be much better off banning one-time use plastic items
Quite correct.
There is political discussion along those lines in the UK.
How many decades before we get there is another matter.

JimB
 

large_ghostman

Well-Known Member
Most Helpful Member
#29
Quite correct.
There is political discussion along those lines in the UK.
How many decades before we get there is another matter.

JimB
Apparently 18 months for Scotland Jim! Looks like Scotland will be the first. Do you watch first ministers questions? It was raised the other week, got to admit i am no fan of NS at the moment but she surprised me on this. And i am sure you seen the pics on the news of the highland stags all caught up in fishing nets etc.

I have joined the local beach watch, its a tiny 4 mile beach right opposite us at the back of a golf course, every two weeks we spend 4 hours cleaning it up. No tourists go there its just washed up ****.

So far in the 4 months we been doing it (21 people) we have taken 18 tons of junk off it.
 

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