Plastic washing line for soft plastics

PE PP film recycling washing line

A film washing line has one job: take baled or loose post-consumer soft plastic that arrives full of soil, sand, product residue and the occasional stone, and hand back flake that a pelletising line can actually run. Everything between those two points is contamination removal, and every stage removes something the stage before it physically could not.

The line below is built around that sequence. Nine stages, each with a specific target, and one of them — sink-float separation — decides how pure the finished flake ends up.

What this line runs on

This plastic film crushing, washing and drying recycling line is mainly used for post-consumer soft plastic materials such as HDPE, LDPE, LLDPE film, bags, PP woven bags, raffia, big bags, film, agricultural film (greenhouse film, mulching film, banana film), and PP non-woven.

Those materials look similar on a spec sheet and behave nothing alike on a line. Post-consumer bags carry ink and product residue. Woven sacks carry sand trapped inside the weave, plus sewing thread and labels. Agricultural film carries soil and stones, sometimes at a weight that rivals the plastic itself. Non-woven carries fibres that wrap around shafts.

Spec the washing stages for the dirtiest feedstock you expect to run, not the average one. A line configured for clean industrial film will choke on mulching film; a line configured for mulching film will run clean film without complaint.

Before

Four typical infeed conditions, from field-collected agricultural film through to baled woven sacks. Anything in this range can go on the conveyor; what changes is how hard the washing section has to work behind it.

After

Washed film flake as it leaves the drying section, still faintly damp. This is the standard output of the line without the optional squeezer.

Run the same line on coloured feed, or fit the squeezer dryer at the end, and the output changes shape as well as moisture. These four are all products of one line configured differently.

How the line is laid out

Material enters at the conveyor, moves through size reduction, then through three separate cleaning principles in sequence, then through two stages of water removal before it reaches the silo. The layout is linear on purpose — every transfer point is a place where wet flake can hang up, so the fewer direction changes, the better the line runs unattended.

Line capacity and what each tier costs you

Four standard tiers, from 200–300 kg/h up to 1500 kg/h. Output is the number most buyers start from, but it is rarely the number that decides the purchase. Floor area and water supply usually do.

Two things worth reading off that table before you pick a tier. Floor area nearly triples between the smallest and largest line, from 350 m² to 1000 m² — if your building is already up, that constraint may settle the decision for you. And water consumption scales faster than output does: five times the throughput needs roughly six times the flow. A site on limited water supply will hit that wall before it hits any power limit.

Installed power in the table is connected load, not measured draw. Actual consumption runs lower, because not every motor sits at full load at the same time.

Water, power and the people the line needs

A film washing line is a wet process, and water is the utility that most often decides whether a site can host one. Four stages draw on it: the wet crusher, the friction washer, the sink-float tank and the high speed friction washer. Between them they need 4–5 m³/h at 200–300 kg/h and 20–30 m³/h at 1500 kg/h.

Those figures are circulating flow, not fresh intake. Dirty water leaves each stage, drops its solids in settling and filtration, and returns to the tanks. What has to be topped up is only the water that leaves with the wet flake and the water that evaporates. The material that genuinely leaves the site is the sludge — soil, sand, fibre and the sunk fraction from the float tank — and that needs a disposal route planned before commissioning rather than after.

Power behaves more predictably. Installed load runs 110–160 kW on the smallest line and 380–600 kW on the largest; because the crusher and the friction washers never peak together, measured draw sits below the connected figure. Manpower is modest for the throughput: 2–3 operators on the smallest tier and 6–8 on the largest, most of them on the infeed side sorting and feeding rather than on the machines themselves.

Key equipment, stage by stage

Eleven machines, in the order material passes through them, grouped into the four things the line actually does: get material in and cut it down, clean it, take the water back out, and store or densify what is left. The last machine is optional and depends on what you intend to do with the flake.

Conveyor

Transports material to the shredder or crusher. High side walls suit varied materials — bulky film that would spill off a flat belt stays on this one.

Shredder

Pre-shreds material. Available as single shaft or two-rotor, heavy duty type for pre-shredding, with Siemens PLC control.

This is where baled and bagged feed becomes something the wet crusher can accept. A whole big bag will not feed a crusher; a shredded one will.

Wet crusher

Wet crushing pre-washes the material and avoids the problem of flying dust and smoke. It turns large material into small pieces in this module, which improves the washing result and makes the final product easier to pack. V rotor and blade design, easy operation.

Crushing under water does two jobs at once: it sizes the material, and the water carries away the grit that crushing releases — grit that would otherwise ride downstream on the flake.

Friction washer

Particular removal of sediment mud and sand from agricultural film by friction and mass water flushing. Removes sand, dirt and adhesives through high-speed rubbing.

Sink-float washing tank

Separates PE and PP, which float, from heavier impurities, which sink.

This is the only stage on the line that removes contamination by density rather than by force. Grit, stones, metal fines and any PET or PVC fragments that came in with the feed all sink out here. Nothing downstream can do this job.

High speed friction washer

High speed and efficiency washing equipment, running at 1200 rpm with dynamic balance treatment.

Screw loader

Transports material with water to downstream equipment. All parts in contact with water are made of stainless steel.

Dewatering machine

A centrifugal dryer with a rotor given dynamic balance treatment and an octagonal screen. Each vane top side is equipped with a stainless steel block, replaceable after wearing. Runs at 1440 rpm.

The replaceable wear block matters more than it sounds. Vane tips are the fastest-wearing surface in the whole drying section, and on machines without replaceable tips the entire rotor becomes a consumable.

Pipe drying system

Reduces moisture at 1500 rpm with an electrical heater. Better efficiency for thick film and bags.

Centrifugal drying throws off free water. What it cannot reach is the moisture held in folds and creases — which is exactly what thick film and heavy bags carry most of. That is the gap this stage closes.

Silo

Stainless steel construction, sized to order.

Squeezer dryer (option)

Removes moisture to 3–5% and compacts material through mechanical friction and electric heating.

Worth adding if the flake is going straight into pelletising or into a long-distance shipment. Flake at 3–5% moisture extrudes without a vented barrel fighting the water, and it ships at a far better density than loose washed film.

What comes out, and where it goes

The line produces two named products, and which one you get is decided by a single piece of equipment rather than by how the washing section is set up.

Product A is soft film or raffia flake at 60–100 mm. That is the standard output of the line as configured above, taken from the silo after pipe drying. It sells as washed flake to compounders and film producers, or it feeds your own pelletising line directly. Flake this size handles well in big bags and pneumatic conveying, but its bulk density is low, which is what makes it expensive to ship any distance.

Product B is semi-molten slices — what the specification table calls wine bottle stoppers, after their shape. This is what the optional squeezer dryer produces: moisture down to 3–5%, and the flake compacted into dense irregular lumps instead of loose film. The density gain is the point. It stores in a fraction of the space, it ships economically, and it feeds an extruder without the barrel having to boil off water it should never have received.

If you are selling washed flake to a local buyer, Product A is usually enough and the squeezer is capital you do not need. If you are pelletising on site, or shipping across a border, the squeezer normally pays for itself on freight and extruder throughput alone.

See the line running

Models & specification

Frequently asked questions