Plastic Recycling Machines General Knowledge

1.Choose goods with minimal packaging, and which are packaged in a material that can be recycled or returned in your area.
2.Try to reduce the need to throw away plastics. For example, take a reusable shopping bag to the supermarket or corner shop, or re-use the bags you were given last time. Don’t accept a bag if you don’t need one. When they are beyond reuse, plastic carrier bags can be put into collection banks at some Morrisons, Tesco and Sainsbury’s supermarkets.Rather than throwing them away, give plastic toys or containers to children’s scrap stores or playgroups for reuse. Further details can be found here
3.Use plastic containers and bags again or make them into something else. For example use yoghurt pots to grow seedlings, use the top part of drinks bottles as cloches for plants and offer clean plastic carrier bags to charity shops.
4.Buy products that are refillable.
5.Think of ways of reducing the need for packaging. Don’t add extra packaging yourself - a melon, a grapefruit or a bunch of bananas already has natural packaging - does it need to go in a plastic bag as well as your shopping bag, and does that already efficiently packaged dairy product or piece of meat really need another wrapper?
6.Ask your local authority recycling officers which materials are currently collected or may be collected in the future.
7.Look for products, e.g. bin liners and refuse sacks, made from recycled plastic, now available in many supermarkets. Also look out for products packaged in at least partially recycled material. For example, Shell Oil’s 1 litre and 4 litre Helix oil packs now contain a proportion of recycled plastic, collected from domestic and industrial waste.
8.If it does not already run one, suggest to your local authority that it considers starting a plastics recycling scheme. The development of market opportunities has meant that at the moment demand is outstripping supply of plastic bottles, so new initiatives are needed to feed the process and ensure its success.
9.Encourage your local authority to buy products, such as street furniture, made from recycled plastic rather than wood.
10.When you put plastic bottles in plastic bottle recycling machines, or even in your bin, ALWAYS REMOVE THE BOTTLE TOPS.  This also enables them to be crushed more easily so they occupy less space.

Reference:http://www.wasteonline.org.uk/resources/InformationSheets/Plastics.htm

Drying, together with cutting, is one of the difficult step of any plastic recycling machines.

Drying is easy when talking about thick flakes of any plastic material.

For example drying HDPE flakes from plastic drums is the easiest job in this world because thickness is in the range of two or three millimeters, the material is elastic so you can put it into any spin dryer and you get them dry.

The matter becomes a little different when happening to thin flakes out of a film line, and for thin around 20 microns (of millimeter) or less, or brittle materials like Polystirene, PC, etc.

Let’s see one problem at a time.

This film first.

If your centrifugal dryer leaves one milligram of water per square centimeter (or change the units but the general concept remains) and your flakes weighs one gram, moisture content will be 0,1% and everybody is happy.

Because the centrifuge performs the same way, doesn’t matter the thickness of your flakes, the same one milligram of water per square centimeters means 10% if the flake weighs 0, 01 gram.

Most of everybody uses hot air for final drying, and because hot air cost a lot of energy, one matter is to start from a moisture content of 2% and a completely other one is a10% starting point.

So, before sizing the hot air drying system, you better care about the % of moisture out of your dryer, whatever it is.
We do love centrifuges for quite many reasons:
First is the fact we can get very low moisture content, even with very thin materials, and very proud of this.
Second because any centrifuge, while drying, it washes as well because it is the combination of friction with water presence.
Third because even the most sophisticated centrifuge is nothing but a rotor spinning into a screen basket that means it is an easy to maintain machine and cannot give lots of problems.
So, as far as today, the very best way we know to get plastic flakes dry, is to go with a well performing centrifuge.
Centrifuges can be very different and the one that makes thin film dry will make 30% fines running Polystirene so diameter, shape of the paddles, size of screen holes and may be something else should change accordingly.
After getting flakes mechanically dry, for some plastics, we will need further drying to get the best possible quality.
We’ll talk about Crystalline Polymers later in this chapter because they need something very specific.
For all other polymers, what we do suggest, is to get a good extruder with a venting, better with two, and feed it straight with the flakes you got after the centrifuge.
This what we do in all cases but one; dealing with film, doesn’t matter the thickness, washing and drying is done with flakes of about 30-40 mm. in size and any force feeding (we know of) accepts only way smaller flakes so further cutting is needed.
Because any granulator will make friction by cutting, meaning developing heat, and then, by blowing, flakes lose some more humidity and by the time they get to the extruder, will be dry enough for pelletizing.
Crystalline Polymers, as we said, need a chapter by its own
PET and PC in fact don’t like the mixture of water (moisture) and heat together plus the fact they are hygroscopic by themselves. (PA performs the same way even not being crystalline)
So if you dry and leave them in a storage place they will get moisture from the air and the energy you have been using to dry them is just thrown away.
Drying should occur just before extrusion and moisture content is measured in PPM and not a %
Both material need a dryer where they stay for sometimes (few hours) with or without vacuum and this because they should release the moisture that’s inside the flakes, or pellets
If these polymers are not completely dry, during extrusion IV (Intrinsic Viscosity) will decrease a lot and polymer loses its characteristics.
Mechanical drying at the end of the pp film drying line should deliver a flake with a moisture content of 0,5-0,6% and after this it will be a dryer unit job to decrease it to nothing (a good dry flakes should have 20 PPM before extrusion)

There are about 50 different groups of plastics, with hundreds of different varieties. All types of plastic are recyclable with plastic recycling machines.

To make sorting and thus recycling easier, the American Society of Plastics Industry developed a standard marking code to help consumers identify and sort the main types of plastic.

These types and their most common uses are:

1.PET - Polyethylene terephthalate - Fizzy drink bottles and oven-ready meal trays, peanut butter jars . PET types can be recycled by PET bottle washing line.

2.HDPE - High-density polyethylene - Bottles for milk and washing-up liquids, motor oil HDPE types can be recycled by PE granulating line.

3.PVC - Polyvinyl chloride - Food trays, fast food service items and shampoo, cooking oil bottles

4.LDPE - Low density polyethylene - Grocery bags and can liners.

5.PP - Polypropylene - Margarine tubs, microwaveable meal trays, bottle caps, yogurt containers, straws. PP types can be recycled by PP granulating recycling line.

6.PS - Polystyrene - foam meat or fish trays, hamburger boxes and egg cartons, vending cups, plastic cutlery, protective packaging for electronic goods and toys (packing peanuts).

7.OTHER - Any other plastics that do not fall into any of the above categories. - An example is melamine, which is often used in plastic plates and cups.