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Flexible, durable and versatile

Semi-transparent polyethylene film rolled up

Polyethylene, or PE for short, is the most widely used thermoplastic in our society and an essential part of modern life.
As a versatile and cost-effective polymer, it is used in a wide range of industries and products. Its popularity is due to its excellent combination of properties such as high durability, chemical resistance, flexibility and ease of processing. From packaging, pipes and containers to medical implants, polyethylene has become an integral part of our everyday lives.

The History of Polyethylene

In the early 1950s, the commercial breakthrough in polyethylene production came with the development of the Ziegler-Natta catalyst process, which uses titanium-based catalysts to enable production at reaction pressure and eventually lower the reaction temperature to normal pressure and room temperature. For this invention, Karl Ziegler and Giulio Natta were awarded the Nobel Prize in Chemistry by the Royal Swedish Academy of Sciences in 1963.
From 1943 to 1969, Ziegler was director of the Max Planck Institute for Coal Research, founded in 1912, in Mülheim an der Ruhr, Germany, about 5 km from SIEBTECHNIK TEMA GmbH, which has been producing centrifuges at this site since 1922.

The future is sustainable

Up to now the raw material e.g. for Polyethylene derivatives is natural gas and crude oil.

Herstellung von Kunststoffen

All of these uses cause, among other things, carbon emissions during the production, use and/or end-of-life of these products. Therefore, carbon-neutral fossil fuel substitutes must be used to achieve the overall goal of net zero carbon emissions.

In the near future, the industry will turn to sustainable feedstocks for the chemical industry, such as Synthetic Ethylene. Here, specific power-to-chemicals processes are already in place, for example converting CO₂ from biogas and green hydrogen (H₂) into Methanol using renewable energy. This Methanol can be catalytically converted into Synthetic Ethylene using the Methanol-To-Olefins (MTO) process.

Beispielhafter synthetischer Produktionsprozess von Ethylen der Vorstufe von Polyethylen

Beispielhafter synthetischer Produktionsprozess

Ethylene to Polyethylene

The Ziegler- and metallocene-based catalyst families have proven to be very flexible in the copolymerization of ethylene with other olefins and form the basis for the wide range of polyethylene resins available today.

Depending on the process, different types of PE with different properties can be produced. They are categorized based on their density, molecular weight and branching structure. Different types of polyethylene result, such as high density polyethylene (PE-HD or HDPE), linear low density polyethylene (PE-LLD or LLDPE) and low density polyethylene (PE-LD or LDPE).

The industry introduced solution processes, gas-phase processes and slurry processes to improve the specific properties of HDPE and created an expanding variety of HDPE.

What are centrifuges used for?

High Density Polyethylene (PE-HD or HDPE)

Immediately after the invention of the process and its first implementation in industrial production, SIEBTECHNIK TEMA supplied the first decanter centrifuges for solid-liquid separation of HDPE in the 1960s. SIEBTECHNIK TEMA continuously working decanter centrifuges are used in the slurry HDPE processes where HDPE solid particles are separated from Hexane or Pentane after multiple reaction steps.

Today‘s multiple-reactor suspension processes enable the production of a wide range of HDPE derivatives.


HDPE Prozessschema

HDPE Prozess

Processes with a multi-stage reactor cascade using Ziegler catalysts that tailor the multimodal molecular weight distribution required for each HDPE grade are used worldwide.

The high demand for HDPE in industry and private households today requires large production plants that manufacture several hundred thousand tons of HDPE annually with SIEBTECHNIK TEMA decanters.

The trend is clearly towards large decanters, which SIEBTECHNIK TEMA has significantly developed further so that they can provide many years of low-maintenance, high-performance service in the gas-tight process.
In addition to the excellent separation results, our customers appreciate the flexibility of our decanter centrifuges even for difficult HDPE products with very high wax contents at extremely high solids throughputs.

Many other production slurry processes exist.

Recycling of HDPE

Novel recycling processes that separate HDPE from composite material and reprocess it into granules using CONTURBEX filtering centrifuges from SIEBTECHNIK TEMA..

Polytunnel on a strawberry field. Polyethylene film for agriculture
Close-up of HDPE (High Density Polyethylene) pipes
Milk bottle made of HDPE (high density polyethylene)
LLDPE food packaging (Linear Low Density Polyethylene)

Ultra-High-Molecular-Weight PE (PE-UHMW or UHMW-PE)

The material is processed into fibers and then spun into yarn that is used to make armor, cut-resistant gloves, and other demanding applications such as high-performance sailing, suspension lines on sport parachutes and paragliders, rigging for sailing, kites, and kite lines for kite sports, and in the medical industry for fibers for surgical applications and hip and knee prostheses.

UHMW-PE has polymer chains many times longer than HDPE. Separation from the solvent is accomplished with gas tight SIEBTECHNIK TEMA decanter centrifuges.

Chlorinated Polyethylene (PE-C or CPE)

In the production of CPE SIEBTECHNIK TEMA filtrating centrifuges made of High Alloy Stainless Steel or Titanium are used. The processing takes place under usage of hydrochloric acid.

SIEBTECHNIK TEMA decanter centrifuge DZ 7. View from the drive side of the decanter.
Screen decanter TURBOSCREEN type TSDT 1100
CONTURBEX sieve screw centrifuge-for sodium carbonate or soda ash
Schubzentrifuge SHS für Kaliumchlorid

Centrifuge Components Materials

Centrifuge components must not only withstand high forces, but also process-related stresses such as corrosion, wear and high temperatures. Cost and availability of materials also play an important role. Our customers select the necessary product-contacting materials according to these very specific requirements.

Duplex and high-alloy stainless steels, Hastelloy® and titanium materials for a wide variety of processes and stresses are part of our daily business in centrifuge construction. Our quality management has developed very detailed and cost effective processes for design, manufacturing processes and component testing based on European guidelines.

Typical sheet metal and forging materials for centrifuge wetted components include

  • EN 1.4404 / AISI 316L
  • EN 1.4571 / AISI 316Ti
  • EN 1.4462 / AISI 318LN / Duplex
  • EN 1.4410 / AISI F53 / Super Duplex
  • Lean Duplex
  • EN 1.4539 / AISI 904L
  • EN 1.4547 / 254SMO®
  • EN 1.4529 / AISI 926
  • EN 2.4819 / INCONEL® Alloy C-276
  • EN 2.4602 / Hastelloy® C22
  • EN 2.4610 / Hastelloy® C4
  • EN 3.7035 / Ti-II / Titan 994-Ti-grade 2
  • EN 3.7235 / Ti-IIPd / Titan 994 Pd-Ti-grade 7
  • and their casting materials
SIEBTECHNIK sieve screw centrifuge CONTURBEX H700 for lactose - hall view with several machines

Screen scroll centrifuge CONTURBEX

The CONTURBEX is a continuously operating, filtering centrifuge with a very wide range of applications.

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SHS pusher centrifuge in fertilizer production

SHS pusher centrifuge

The SIEBTECHNIK TEMA SHS pusher centrifuge has established itself and proven itself as a modern high-performance unit in many industries.

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SIEBTECHNIK TEMA decanter centrifuge DZ 7. View from the drive side of the decanter.

Decanter centrifuge – solid bowl

Our decanters are individual, functional and versatile. They offer highly efficient separation of even the finest solids with almost complete clarification of the liquid phase.

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SHORTBOWL decanter for lactose in the production hall in Mülheim an der Ruhr

SHORTBOWL decanter centrifuge

Due to the special geometry of the rotating parts, the SHORTBOWL decanter centrifuge - solid bowl is best suited for separating fine solid particles with a high specific density difference to the liquid phase.

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Screen decanter TURBOSCREEN type TSDT 1100

TURBOSCREEN screen bowl decanter centrifuge

It combines the process engineering advantages of a sedimenting decanter and a filtering centrifuge in one machine.

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STReAM Zentrifugen - SIEBTECHNIK TEMA Remote Advanced Monitoring mit optionaler Cloud-Anbindung.

STReAM Centrifuges

SIEBTECHNIK TEMA Remote Advanced Monitoring
Your digital module for preventive centrifuge maintenance - with optional cloud connection

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Ölzustandsüberwachung Headerbild - gelbes Getriebeöl

Fluid Observer

We have developed an oil quality monitoring system specially tailored to our centrifuges. Reduce downtimes and extend your machine running time with the SIEBTECHNIK TEMA Fluid Observer!

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