One Line, Two Polymers

The first thing worth being clear about is that PP and HDPE do not need two lines. The published FAQ answers it directly: rigid PP and HDPE share the same process route, with the separation and drying settings adjusted to the mix. That single sentence is what makes the WL series a product line rather than two product lines sold separately.

The practical consequence shows up at the separation stage. Float-sink separation is published as removing the sinks — metal, stone and heavier plastics — while the PP and HDPE that the line is built for stay with the float fraction. A mixed rigid feed of crates and drums does not ask the line to split PP from PE; it asks the line to strip everything that is not PP or PE away from them. That framing keeps the equipment list short and the process route the same across feedstocks.

The material fit is published just as plainly: crates, drums, buckets, caps, pipe offcuts and injection-molded scrap in PP and HDPE. If your feed is film, the structures change — our vertical versus horizontal dewatering comparison covers why film and rigid flakes are handled by different machines — but within the rigid world, one line covers both polymers.

Six Stages, Six Jobs

The published process sequence has six stages, each tuned to the feedstock rather than fixed at a catalogue setting. Read them as a chain of contamination removal, not as a list of machines:

• Feed. Baled or loose rigid scrap is metered into the line. Metering matters because every downstream stage is sized on a steady load.
• Crushing. The PS-series crusher reduces material to a size the washer can handle. The published guidance for friction washing is a pre-crush of typically 10-30 mm — too coarse reduces cleaning, too fine complicates separation — and the PS screens run from 3 to 15 mm for an output typically in the 5-20 mm range. Claw-type blades are the published fit for hard plastic.
• Friction washing. The FW-series friction washer strips soil, labels and residue off flake surfaces. Rinsing alone removes loose dirt; the adhered oil, label adhesive and compacted soil need mechanical friction against the polymer surface, combined with spray rinsing. The FW series runs at 500-800 rpm across its models, and larger or heavily contaminated lines use two or three washers in series.
• Float-sink separation. Density separation removes the sinks: metal, stone and heavy plastics. This is the stage that makes a mixed rigid feed survivable — and the reason metal removal upstream is still recommended before the crusher, which is not designed for metal.
• Dewatering. Mechanical dewatering removes the bulk of the surface water. On rigid flakes the vertical centrifugal machines are published at a dewatering rate of 95% or higher.
• Drying. Thermal drying brings the flakes to the moisture your granulator accepts, and the series is published at an outlet moisture of 2% or lower.

Two stages deserve a closer look because they carry most of the cleaning load. Friction washing is where the contamination that survived crushing gets attacked: oil, glue and soil are lifted from the surface, then carried away by spray water, and adhesive residue left after de-labeling is one of the main things the stage removes. For oily material, the published position is that heated wash liquor improves results — and whether heat is needed for your feed is confirmed in a material test, not assumed from a brochure.

Float-sink is where the line earns its tolerance for dirty feed. Soil and sand, ferrous metal, and heavier plastics all leave here instead of travelling into the dryer or, worse, into a granulator. The published contamination list for the line — soil and sand, paper labels, product residue, cap and closure fractions, ferrous metal — maps onto the stages one to one, and that mapping is the real specification of the line.

The Published WL Table

The line is published in four reference configurations. Note that the table carries three consumption columns at once — capacity, water and power — and one quality column. Final sizing is confirmed after a material study.

Three things are worth reading out of the table together. First, the water column scales almost linearly with capacity — from 3-5 t/h on WL-500 to 12-20 t/h on WL-5000 — which is why water infrastructure deserves the same planning attention as electrical supply. Second, the outlet moisture column does not move: ≤2% across the range, because the drying stage is sized per project to hold the published figure regardless of throughput. Third, the typical-feed column widens as the models grow, from household plastics up to mixed rigid and film — the larger the line, the more contamination variance it is designed to absorb.

Every machine inside the line — the single shaft shredder for bulky feed, the PS-series crusher, the friction washer, the dewatering machine — is also available as a standalone unit with the same published specifications, which matters when you are upgrading an existing line stage by stage rather than building new. For a worked example of what one output stream looks like downstream, our post on PP food container recycling follows the hot-wash route for a single rigid stream.

Water: The Second Consumption Figure

Capacity is the number everyone quotes; water is the number that decides whether a site can host the line. The published range is 3 to 20 t/h depending on model, and the published design answer is a closed-loop water system including settling, filtration and water treatment.

The closed loop is what turns those circulation figures into an operating cost you can plan around. Settling takes the heavy fraction out of the wash water, filtration handles the fines, and water treatment keeps the recirculated water from progressively re-contaminating the flakes it is meant to clean. The friction washers contribute their own published water figures — 2-4 m³/h on FW-500 rising to 8-12 m³/h on FW-1200, depending on rinse intensity — and the rinse stage matters as much as the friction stage, because the spray is what carries the released contamination away from the flake surface.

When comparing quotes, ask what the water figure includes. A line specified without its water treatment loop will look cheaper on the capacity column and more expensive every month after commissioning.

What to Send With the Enquiry

The line pages close with the same request: send material details. Four inputs turn a capacity question into a line configuration:

• Material form — crates, drums, buckets, caps, pipe offcuts, injection-molded scrap, and the PP/HDPE mix ratio if known, since the separation and drying settings are adjusted to the mix.
• Contamination level — the published scope covers soil and sand, paper labels, product residue, cap and closure fractions and ferrous metal; the heavier each class, the more wash stages get configured.
• Hourly capacity — honestly stated, because the WL table trades capacity against water and power, and the model is confirmed after a material study.
• Target flake quality — what your granulator or end customer accepts, since that decides the drying stage and the final ≤2% moisture commitment.

Send those four and the published table does most of the work: WL-500 through WL-5000 covers 500-800 kg/h up to 3,000-5,000 kg/h, the closed-loop water design sizes itself from the model, and a material study on your own bales replaces the catalogue ranges with numbers for your yard.

Frequently Asked Questions