Olive oil decanter centrifuge for small-scale olive oil mills - Sigma 6

The new Alfa Laval Sigma 6 two-phase decanter centrifuge is the perfect choice for olive oil extraction in small and medium-sized mills. Characterized by gentle product treatment and minimal heating, Sigma 6 produces olive oil of the highest quality. Thanks to the two-phase design, Sigma 6 consumes much less water and energy than three-phase decanters, and it does not produce any black water. Sigma 6 is therefore an ideal solution for oil producers who have a passion for both quality and the environment.


Suara pelanggan

Fabricadouro, Portugal

The results have been great. We get the yield we were looking for along with maximum quality.”
The relationship between Fabricadouro and Alfa Laval is really good. Alfa Laval always solves our problems. Their people are very close and available to us during the season. I would recommend Alfa Laval to anybody. They will be well served by buying Alfa Laval equipment.”

- Alvaro Vega, Owner of Fabricadouro

De Carlo, Italy

We have been using Alfa Laval equipment for the last 50 years, because Alfa Laval is always focused on improving the quality and efficiency of their products.
This has allowed us, on the one hand, to improve the quality of our olive oil. And on the other hand, we have been able to optimize costs, reducing the consumption of water, improving temperature control, and improving the flexibility and adaptability of the decanter for the product.
Sigma 6 gave us two advantages: the first is that we save on energy needed to heat up the water, and we also eliminated the need to spread black water in the field.
As we see with Sigma 6, they can help us to simplify mill operations and, where it is possible, increase the quality of oil we produce.

- Francesco De Carlo, Quality and Production Manager of De Carlo Olive Oil. 

First in olive oil

Olive oil decanters with supreme oil quality and high yield

Alfa Laval Sigma 6 is specifically designed for small and medium-sized olive oil producers. Thanks to a range of unique technical features, Sigma 6 preserves all the flavours of the olives while ensuring outstanding extraction efficiency and operating reliability.

Two-phase olive oil extraction is becoming more and more popular due to the low water and energy consumption, as well as the absence of black water. Alfa Laval Sigma 6 features the same technologies as our larger Sigma models, giving olive oil producers of all sizes access to the latest technology for oil extraction. A Sigma 6 works equally well for batch and continuous production.

And, as always when partnering with Alfa Laval, you have the full backing of our service network in case you need our assistance.

  • Outstanding oil quality as a result of very gentle product handling and minimal heating
  • The unique designs of the conveyor and bowl give Sigma 6 exceptionally high extraction efficiency, even at high flow rates
  • 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
  • Extra wear protection of the feed zone and solids outlet ensures high operating reliability and a long lifetime
  • Low water and energy consumption, no black water

First in quality

With an Alfa Laval Sigma 6, you can extract olive oil with all the flavours and nutrients of the olives intact. The key to high quality is to minimize the heat produced when the paste and oil are slung against the decanter walls during extraction. A Sigma 6 features a unique feed zone that gently accelerates the paste and a special liquid outlet that ejects the oil very close to the axis of rotation. Both of these innovations result in minimal heating, ensuring the highest product quality.

olive oil decanter centrifuge Alfa Laval

First in olive oil extraction efficiency

The Alfa Laval Sigma 6 features several innovations that enhance the efficiency of the oil extraction. The extra-long bowl, in combination with a liquid outlet that is very close to the feed zone, makes the retention time in the decanter longer, which in turn means you can extract a higher portion of the oil in the olives. The Sigma 6 operates with a thin layer of olive paste and with high differential speed, i.e. the conveyor rotates at a substantially higher speed than the bowl, allowing it to handle large flow rates with very high extraction efficiency.

Alfa Laval decanter centrifuge screw conveyor

First in reliability

Alfa Laval Sigma 6 is engineered and built for reliable operation – year in and year out. The Sigma 6 shares the same robust design that has made our Sigma models for large-scale production so popular among industrial olive oil producers. The feed zone and solids outlet have a tungsten carbide liner for wear protection, and the conveyor edges are covered with a flame-sprayed hard coating material. This improves the wear resistance of these components by five times.

Φυγοκεντρικός διαχωριστήρας Decanter ελαιόλαδου

First in environmental sustainability

The two-phase extraction process requires little or no dilution water, meaning that water consumption is much lower than is the case for three-phase extraction. It also means that the process does not produce any black water and that no energy is required for heating the dilution water. This is obviously good for the environment and lowers operating costs, especially in areas where water is scarce and where it is hard to dispose of black water. Alfa Laval decanters have very low power consumption thanks to the special design of the feed zone, the VDF-controlled motor and the unique solid and liquid outlets.

clean water sustainability

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.