distinguish between plastic and glass

Thread Starter

Ilyas Ennaoui

Joined Apr 29, 2018
2
Hello everyone .
I am working on a project, and I stuck in one part, concerning, how to distinguish between plastic and glass, and papers if possible.
what kind of sensors can I use in this case.
thank you in advance
 

jpanhalt

Joined Jan 18, 2008
10,108
Welcome to AAC.

Try the well know flame test. You can also measure refractive index and numerous other properties. Do you have any clue what the "plastic" is or even a good definition for "plastic" versus "glass." (FYI, a lot of compounds form "glasses." I assume you mean ordinary soda lime glass.)
 

Thread Starter

Ilyas Ennaoui

Joined Apr 29, 2018
2
Welcome to AAC.

Try the well know flame test. You can also measure refractive index and numerous other properties. Do you have any clue what the "plastic" is or even a good definition for "plastic" versus "glass." (FYI, a lot of compounds form "glasses." I assume you mean ordinary soda lime glass.)
Thanks for your answer.
I want to make a Smart trash that will be able to sort these components
 

jpanhalt

Joined Jan 18, 2008
10,108
Can you give some more clues? Will the materials be in a single layer on a conveyor? Will they be crushed? One option is to crush the whole pile and use a sieve to sort out the smaller glass particles. Then use flotation for a final separation (glass is heavier than water; most plastics are lighter).

What are you thoughts on what is beginning to sound like a homework problem?
 

-live wire-

Joined Dec 22, 2017
912
You can measure how reflective they are with certain sensors. Or, for plastic, it would probably float while crushed up glass will sink (in water). So you just need to crush it all up and pour it into water. Before that, try mixing it all up and blowing it all around. The light papers would fly around but heavier things would not. Then use huge induction heaters to melt all the metal recyclables after you take the other stuff out. As a bonus, the molten metal will melt the remaining trash that people threw in. This assumes there are also metal cans and stuff.
 

DickCappels

Joined Aug 21, 2008
6,542
Just a guess but you will probably get good results measuring the propagation velocity of an acoustic wave, perhaps something as simple as hitting the bottle with a solenoid and watching the wavefront travel for a distance in the medium in question.
 

ebp

Joined Feb 8, 2018
2,332
In a heavily automated sorting plant I know of, glass is taken out early in the process with gravity sorting. Plastics are sorted late in the process using a conveyor, optical recognition and air jets. This is established technology in quite widespread use.
 

wayneh

Joined Sep 9, 2010
16,399
This is established technology...
Bingo. Let's not reinvent the wheel.
I was thinking a fluidized bed, a column with upflow air and maybe an augur up the middle, would allow separation by bulk density. Glass would "sink" while anything plastic would "float". You then adjust the takeaway positions and rates and the thing can operate continuously at steady state.
 
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