Olive oil decanter centrifuge for industrial-scale olive oil mills - Sigma 8

The new Alfa Laval Sigma 8 two-phase olive oil decanter centrifuge takes industrial-scale extraction of olive oil to a new level. Sigma 8 combines outstanding yield and operating reliability with supreme product quality and minimal operating costs. With high-capacity processing capabilities, Sigma 8 is ideal for large-scale producers of olive oil.


Customer's voice

Sociedad Agricola Ouro Vegetal, Portugal

The Alfa Laval Sigma 8 decanter was installed for this season, and up to now it has already processed 4000 tonnes of olives. Our first impression of the Sigma 8 was extraordinary, both in terms of yield and separation efficiency.
SAOV has been partnered with Alfa Laval since we started in 2004. Our relationship with Alfa Laval is very close and extremely good. It is familiar, based on mutual help, information sharing, companionship and reciprocal trust.
From the start, all Alfa Laval decanters we have tested have been efficient, reliable and long-lasting. In fact, they have been working for a long time, showing the long-lasting and long-term reliability of the equipment.

- Rita Marques, Food Quality Manager, SAOV

First in olive oil

Olive oil decanters with high yield and low operating costs

Alfa Laval Sigma 8 is the latest addition to Alfa Laval’s range of two-phase decanters for olive oil extraction. Building on experiences from more than 50 years of developing decanters for olive oil production, the new Sigma 8 features a number of innovations that ensure high yield, excellent retention of flavours and nutrients, low operating costs and high uptime.

Alfa Laval olive oil decanters have a solid reputation for reliable operation. Their robust design is proven to withstand tough operating conditions during harvesting season – year after year, in mills of all sizes.

With Alfa Laval as your partner, qualified help is just a phone call away. Our network of field service engineers and service centres is ready to support you with all types of service and spare parts.

  • Exceptional extraction efficiency, even at high flow rates, thanks to Sigma 8’s unique conveyor and bowl designs
  • Low power and water consumption
  • Very low solids content in extracted oil, resulting in lower load on the subsequent clarification stage and reduced downtime for flushing of the high-speed separator
  • Outstanding oil quality thanks to gentle product handling and minimal heating
  • Tungsten carbide wear protection: lining of feed zone and solids outlet, tungsten carbide tiles on the conveyor flight (the entire length)
olive oil decanter centrifuge Alfa Laval

First in yield

Alfa Laval Sigma 8 is designed for high yield. The bowl is longer than in traditional decanters. In combination with a liquid outlet that is very close to the feed zone, this increases retention time in the decanter and, in turn, the extraction efficiency. By operating with a thin layer of olive paste and with a high differential speed (i.e. the conveyor rotates at a substantially higher speed than the bowl), a Sigma 8 can extract oil with great efficiency at large flow rates.

Olive Oil clarification or purification

First in taste

With an Alfa Laval Sigma 8, you ensure all the flavours and nutrients in the oil are kept intact during extraction. For supreme product quality, it is crucial to minimize the heat generated by forces acting on the paste and oil in the decanter. The unique feed zone in a Sigma 8 accelerates the paste very gently. Together with a special liquid outlet that ejects the oil very close to the axis of rotation, this results in minimal heating and the highest possible product quality.

Industrial scale olive oil millers 640x360

First in uptime

The sturdy design of an Alfa Laval Sigma 8 ensures reliable operation under tough conditions. The feed zone and solids outlet are lined with tungsten carbide for extra wear protection and the conveyor is protected by tungsten carbide tiles. These components are easily replaced when required, and the extra protection increases wear resistance five times.

Olive oil processing industrial scale

First in olive oil production economy

Alfa Laval Sigma 8 is characterized by low operating costs. Two-phase operation keeps water and energy consumption low, and the process does not produce any black water. Alfa Laval decanters feature a number of technical innovations that minimize power consumption, such as a unique feed zone, VDF-controlled motor and specially designed outlets for oil and solids.


How it works

Sigma olive oil decanter centrifuge operating principles

The Sigma olive oil decanter centrifuge design makes sure the incoming paste is effectively separated into oil and wet solids.

The olive paste is fed into the bowl of the unit through a stationary inlet tube, and is then smoothly accelerated by an inlet rotor. Separation takes place in a horizontal cylindrical bowl equipped with a screw conveyor. Centrifugal force makes the oil accumulate at the liquid surface, while the solids settle on the inner wall of the bowl, surrounded by the water separated out of the feed stream.

The conveyor rotates at a slightly different speed than the bowl and moves the solids to the discharge ports in the conical end. Olive oil extraction takes place along the entire length of the cylindrical part of the bowl. The oil is returned to the large end for discharge, and then passes into collecting tanks via a filter.