Too much downtime. (mainly about sorting)
 
 
This is the problem 99% of recyclers are facing.
And it is the most expensive item of the line you cannot even see.
This happens because, first, scraps are never the same, they can contain stones, steel, paper, textiles, you name it.
Machinery are not normally prepared to handle all this so you got in trouble, don't you ?
Yes, you did spend very little to buy your plant but now you realize you cannot make any money out of it, even putting all your efforts and the 25 hours per day you have available.
When I say plastic recycling is a difficult very few takes me into consideration till they start their own system.
Are you one of them ?  If yes keep reading.
Machinery, all kind, cannot handle everything, whatever quantity and quality and workers are not very intersted in your business and they care very little about yourself.
Starting from this general concept, let's see what can be done.
Most of the time a recycling line starts with a conveyor belt where people is supposed to remove whatever is not the kind of plastic you are dealing with.
This may work well from sunrise to sunset but what happens for the rest of the time ?
It happens people don't pay attention anymore, a piece of steel goes into the granulator and you are down for a week time, if everything goes right.
Specially when talking about film scraps, where workers should open bales by hands, you cannot pretend they will be working night time, don't you ?
A metal detector doesn't help much because, when it stops the conveyor too often, workers start the conveyor twice and everything goes through.
A magnetic conveyor removes steel by itself, doesn't need human control and never stops the line.
What about the rest of the craps, like stones, aluminum, stainless steel etc ?
Two ways, first one expensive and 100% efficient and second that can be homemade.
First one is to run film into a double shaft shredder to decrease the size of film and then put a huge aspirator to suck up whatever is light while heavy pieces remain on the conveyor.
This is largely used into garbage separation systems and proven to work very well.
Second way is to lift material up, with a conveyor belt, and have an inclined rubber sheet facing the other side of the conveyor so heavy pieces will jump one way and flat film falls down on another conveyor.
The only unwanted materials, when running film, will be wood and expanded materials floating together with PE.
If material is HDPE bottles, to be positive nothing heavy goes into granualtor it will be matter to put a blower at the end of first conveyor and blow bottles onto another conveyor. (you have just to put back on the conveyor bottles still full of liquid)
Stones and steel will fall on the ground and your granualtor is safe.
When it goes to PET bottles the matter becomes a little more complicated.
First because sorting should be a lot more precise and second because, if this kind of contamination is not removed 100%  you'll find it together with your beautiful clean and dry flakes that will worth nothing.
There is no easy way out in this case or, to better express myself, not a cheap way out.
You can use the same system of HDPE bottles to remove steel, glass and stones but it doesn't work with aluminum cans and PVC bottles.
You already know NIR, X-rays, Eddy current separators and their cost.
There are other systems available but none of them has a 100% efficiency and, unless you are running, at least, 2 tons/hour, none of them is economically viable.
All this is only to talk a little bit about sorting of most common plastic scraps.
But downtime resides aminly in this part of the line because, after granulation, flakes can be dosed to the rest of the line and a constant flow of material with a stated size, weight and other characteristics should make any more problem.
Unless you bought real junk machinery by which, in this case, I (nobody) can do nothing.
Sorry for you about that :-)
 
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