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Recycling bottle caps

This topic contains 5 replies, has 3 voices, and was last updated by  pseudonymous 2 years ago.

Ian Robertson ianrobbo

Recycling bottle caps

19/06/2019 at 17:36

Hi I am new here and already finding the site a mine of information:-)

Sometime in the past our company started collecting bottle caps and unfortunately did not separate them into different types so we now have 4 bulk bags ( approx 3 tonnes) of mixed PP and HDPE tops.

Any suggestions/ideas of what we could do with them?

We also have about 1 tonne (and growing) of granulated PET/PP mix.

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In reply to: Recycling bottle caps

20/06/2019 at 07:48

Hey there @ianrobbo !

bottle caps will “always” be PP or PE (which are from same family Polyolefin).
in order to have best quality of product output, i would recommend only using “food-grade” bottle caps, as the types of additives in them should be limited.

concerning the granulated PET/PP mix, from my point of view you won’t be able to do anything with it; PET & PP have highly different chemical stucture and product output will be very brittle (and not rerecyclable)

hope the info helps you out x)

In reply to: Recycling bottle caps

20/06/2019 at 09:21

Hi – Thanks for that.
I was hoping to be able to somehow separate the PET/PP granulated mix by dumping it in a water tank and then skimming the floating PP off the surface?

In reply to: Recycling bottle caps

20/06/2019 at 09:57

Hi Ian @ianrobbo
there is of course always the option of Pyrolysis and/or separating the PET/PP mix.

Simply shredding the (sorted) caps and selling them as raw material (flakes) is of course also an option.

In reply to: Recycling bottle caps

20/06/2019 at 12:38

I also come accross a posible stess test:
“Hit it hard, if it shatters it’s PP, if not it’s hdpe”

Another point for the sledgehammer shredding method!

In reply to: Recycling bottle caps

20/06/2019 at 15:26

Thanks to @alexsav

“If you have large batches and motivation, you could think of a sink/float method with a liquid medium that has a density between those of PP and HDPE. There is also research for separation of PP and HDPE size particles with hydrocyclones they are quite low cost but require a lot a fine tuning to get good efficiency.”

Float/Sink Separation of PP and HDPE

Study on the light medium separation of waste plastics with hydrocyclones (PM me for the full article)

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