Recycling bottle caps
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.
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)
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?
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.”
Study on the light medium separation of waste plastics with hydrocyclones (PM me for the full article)
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