Equipos Auxiliares

Tanque de Separación por Flotación para PET, PE/PP y Escamas de Plástico Mixto

Un tanque de separación por flotación y hundimiento divide escamas de plástico mixto por gravedad específica en un baño de agua controlado. Rumtoo diseña el tanque según su alimentación real (botellas PET, PEHD, tapas PP, film, PVC), pureza objetivo y tasa de reutilización de agua.

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Plastic floating separation tank for PET, PE and PP flakes

Cómo Elegir su Tanque de Separación por Flotación

Tank volume alone never predicts real-world purity. The machine must be matched to the feed density spread, flake size, contamination load and water-reuse target — here is the selection path that actually works.

1

Mapear la dispersión de densidad y punto de corte

Liste cada polímero: PE 0.91-0.94, PP 0.85-0.91, PET 1.38-1.40. Si la diferencia es menor a 0.02 g/cm³, Rumtoo añade etapas de hidrociclón o electrostática.

2

Elegir longitud del tanque y tiempo de retención

Un tiempo de retención de 60–120 segundos es ideal. Rumtoo dimensiona el tanque para que las escamas viajen a 0.05–0.10 m/s.

3

Dimensionar el bucle de reutilización de agua y lodos

Rumtoo especifica un tanque de sedimentación y bucle DAF para que el 70–85% del agua se reutilice y el lodo se descargue como torta seca.

4

Integrar removedor de etiquetas y lavado en caliente

El tanque opera con carga estable gracias a la integración con las etapas previas, protegiendo la línea de incrustaciones de papel.

Lo que los Compradores Necesitan de un Tanque de Flotación

The business reason to install a sink float tank is not the technology — it is a measurable jump in PE/PP and PET purity, a lower reject rate at the extruder, and a closed water loop that avoids wastewater permits and 30–50 m³/day of fresh water consumption.

Separación de Densidad de Alta Pureza

Pureza típica del 98–99% en un paso. Diseños de doble tanque con ajuste de salmuera permiten alcanzar 99.5%+ para rPET grado alimentario.

70–85% de Reutilización de Agua

El agua de reposición cae a 3–5 m³ por tonelada, ahorrando USD 30,000–80,000 anuales en costos de agua y vertido.

Elimina Papel, Film y Finos Metálicos

Es la etapa clave que elimina el PVC y papel antes de la extrusora. Los intervalos de cambio de malla de la extrusora suelen triplicarse.

Capacidad de 500 a 5000 kg/h

Rumtoo escala la longitud y velocidad del skimmer. Una línea de 5000 kg/h cabe en unos 18 metros con bajo volumen de lodo.

Common Sink Float Problems and Real Fixes

Most poor-separation reports trace back to five production conditions — not the tank itself. This table shows what actually goes wrong in running lines and how Rumtoo corrects it during commissioning.

Problem

PET pellets float instead of sink — extruder rejects rPET for PVC contamination.

Rumtoo Solution

Rumtoo adds a short de-foaming baffle and lowers paddle speed; most "PET floating" cases are actually entrained air in thin bottle-wall flakes. Persistent cases get a brine dosing line that lifts water density to 1.05 g/cm³ for a guaranteed PET-PS separation.

Problem

Water turns gray, filters clog within two shifts and discharge fails limits.

Rumtoo Solution

Rumtoo sizes the sedimentation tank, bag filter and DAF loop so fine label, paper and glue particles are removed continuously. Sludge is de-watered to 60–70% solids in a screw press instead of being pumped out as liquid.

Problem

Paddle agitators foul with film and rope — tank shuts down twice a week for cleanout.

Rumtoo Solution

Rumtoo specifies an upstream trommel and film-rope separator so ribbons and long strands never reach the tank. Paddle geometry is adapted (cut-blade vs flat paddle) to the dominant flake shape in your feed.

Problem

Winter start-up produces black sludge and foul odor from caustic carry-over.

Rumtoo Solution

Rumtoo isolates the hot-wash caustic loop from the sink float bath with a rinse buffer tank and specifies a weekly tank drain/scrub SOP. A pH and turbidity sensor warns before biological growth crosses odor thresholds.

Referencia de Máquina y Principio de Separación por Densidad

Las escamas mixtas entran en un baño de agua donde agitadores de paletas y un flujo transversal llevan las fracciones de baja densidad (PE/PP, 0.90–0.94 g/cm³) a un skimmer superior, mientras que las escamas de alta densidad (PET, PVC, metales) se hunden y se descargan mediante un transportador de tornillo.

Stainless steel sink float tank with paddle agitator and skimmer

Vista de Máquina: agitador de paletas, skimmer de vertedero y tornillo de fondo

El cuerpo del tanque está construido en acero inoxidable 304 o 316L para resistir el lavado cáustico. Los agitadores mantienen el baño en movimiento para evitar la aglomeración; un skimmer de superficie retira la fracción flotante; un tornillo de descarga extrae las escamas pesadas con mínima pérdida de agua.

  • Agitadores de paletas de velocidad variable sintonizados al tamaño de escama
  • Altura de vertedero ajustable para un control preciso del punto de corte
  • Diseño de doble etapa disponible para purificación secundaria de alta precisión

Vista de Proceso: flotación de PE/PP, hundimiento de PET/PVC en línea de lavado

En una línea de botellas PET, el tanque se ubica tras el removedor de etiquetas. Las tapas de PEHD/PP flotan; el PET, PVC y metales se hunden. En una línea de PEHD/PP rígido ocurre lo inverso. En ambos casos, el tanque elimina el polímero incorrecto antes del lavado en caliente para proteger el intercambiador y la extrusora.

  • Separa PET/PVC/metal de PE/PP con 98–99% de pureza en un paso
  • Elimina papel, etiquetas y restos de film que flotan tras el prelavado
  • Circuito de agua que alimenta el bucle de filtración para 70–85% de reutilización
Recycled PE and PP plastic flakes after sink float separation

Sink Float Separation Tank in Operation

Watch how the paddle agitator, weir skimmer and sinking screw conveyor separate mixed plastic flakes into pure PE/PP floating fraction and PET/PVC sinking fraction in a controlled water bath.

Typical Sink Float Tank Use Cases

A sink float tank earns its place in any plastic washing line where the target and contaminant polymers differ by at least 0.05 g/cm³ and the feed is already wet from pre-wash.

  • PET Bottle-to-Bottle Washing Lines

    Removes HDPE caps, PP rings, paper label fragments and PLA sleeves from PET flakes before hot wash. Critical stage for lines targeting food-grade rPET approval from EFSA, FDA or similar regulators.

  • HDPE Milk/Detergent Jug Recycling

    Separates PP caps, PET tamper bands, metal fines and dirt from HDPE flakes produced from milk, detergent and motor-oil bottles. Prepares HDPE flakes for pipe, crate and packaging compounders.

  • PP Rigid Packaging and Caps Regrind

    Splits PP from residual PET, PVC tamper bands and PS labels coming off food tubs, buckets and cap regrind so compounders receive a single-polymer feedstock.

  • Mixed Post-Consumer Plastic Sorting

    Acts as the first bulk density stage for mixed post-consumer curbside input, routing a clean PE/PP float fraction to pelletizing while high-density material is sent to NIR, electrostatic or manual picking.

  • Agricultural Film and Big-Bag Reclaim

    Paired with a pre-wash, the tank floats LDPE film fragments while soil fines, stones and metal wear particles sink — reducing extruder melt filter changes by 2–3×.

  • WEEE and Automotive Plastic Regrind

    Used as a rough density splitter ahead of electrostatic separation to remove metals, glass fragments and rubber from ABS/PS/HIPS-dominant WEEE and automotive shredder residue feeds.

Reference Configurations

These are sizing references. Actual purity, water reuse and sludge volume depend on feed composition, contamination level and the filtration loop selected — Rumtoo confirms the final specification after reviewing your material data.

ModelThroughputTank VolumePowerKey Features
RT-SF500300–500 kg/h2.5 m³3 kWCompact single-stage tank, 304 stainless, for small PET or HDPE lines
RT-SF1000800–1200 kg/h5 m³5.5 kWPaddle agitator + weir skimmer, bag filter loop, suits standard PET bottle washing lines
RT-SF20001500–2500 kg/h9 m³7.5 kWTwin-tank with brine adjustment, DAF loop, 70–80% water reuse
RT-SF50003500–5000 kg/h18 m³15 kWBottle-to-bottle grade twin-tank, 316L, DAF + screw press, 80–85% water reuse

Typical water make-up with a full reuse loop is 3–5 m³ per ton of clean flake. Energy consumption is 20–35 kWh per ton including agitators, pumps and filtration. Rumtoo sizes the unit after reviewing your feed analysis, contamination level and local water and discharge cost.

Sink Float Tank Checklist Before RFQ

Bring these data points to the RFQ and Rumtoo can size the tank, water-reuse loop and commissioning protocol in the first reply — avoiding weeks of back-and-forth.

  1. Polymer Mix and Density Spread

    List every polymer in the feed with its approximate share — PET, HDPE, PP, PVC, PS, PA, metals — so Rumtoo can confirm the cut-point target and decide whether plain water, salt brine, or a two-stage tank is required.

  2. Feed Flake Size and Shape

    Share the flake size distribution (typical working range is 6–30 mm), shape (flake vs film vs granule) and fines content below 4 mm. Particle size controls paddle speed and retention time.

  3. Contamination Load (Paper, Film, Fines, Sand, Metal)

    Specify the expected contamination per ton — paper label, PE/PP film, paper pulp, sand and metal fines. This determines filtration, sludge press sizing and tank cleaning frequency.

  4. Target Throughput and Shift Pattern

    Provide target kg/h, planned shift hours and scheduled cleaning windows. Rumtoo builds around a realistic effective uptime, not name-plate capacity.

  5. Water Source, Reuse Target and Discharge Limits

    Share local water cost, discharge cost and effluent limits (COD, TSS, pH). The water-reuse loop is sized for the economic break-even between make-up water cost and capex.

  6. Downstream Stages (Hot Wash, Friction, NIR, Electrostatic)

    Describe the full line — what comes before and after the tank. Rumtoo adjusts the cut-point, skimmer angle and discharge method so the tank integrates with existing hot-wash, friction and polishing stages.

Sink Float Tank vs Alternative Separation Methods

A sink float tank is the right answer when the density gap is clear and the feed is already wet. This table shows where it wins and where a hydrocyclone, electrostatic separator or NIR sorter fits better.

Decision CriteriaHydrocycloneNIR Optical SorterElectrostatic SeparatorRumtoo Sink Float Tank
PE/PP vs PET bulk separationGood, but high capexWorks if colors differNeeds pre-dryingProven at 98–99% in one pass
Food-grade bottle-to-bottle rPETWorks as polishing stageWorks upstream of washFinal PVC-ppm stageEssential bulk stage, add electrostatic for <50 ppm
Handles paper, label and film finesPoorNot designed for thisBlocks the fieldRemoves them continuously
Water consumptionVery high, high pressureNoneNone3–5 m³/ton with reuse loop
Energy per ton40–60 kWh + pump pressure10–15 kWh30–50 kWh20–35 kWh including filtration
Capex vs operating costHigh capex, high opexVery high capex, low opexMedium capex, low opexLow-medium capex, low opex

Preguntas Frecuentes

¿Puede separar PET de PVC?

No por sí solo, ya que sus densidades se solapan (1.35–1.45 g/cm³). El tanque elimina PE/PP, pero para grado alimentario <50 ppm PVC, Rumtoo añade separación electrostática u óptica.

¿Se requiere agua caliente en el tanque?

La separación ocurre a 25–40 °C. Rumtoo suele aprovechar el calor del lavado en caliente posterior mediante un intercambiador para optimizar energía.

¿Listo para Dimensionar un Tanque de Flotación para su Línea?

Envíe a Rumtoo un análisis de su flujo. Devolveremos un modelo ROI y plan de puesta en marcha en 24 horas.

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