Drs Guy Metcalfe (left) and Kurl Liffman examine granular material after separation in the laboratory-scale Rotary Classifier.

Dr Guy Metcalfe (left) and Dr Kurl Liffman examine granular material separated in the laboratory-scale Rotary Classifier.

Dry solution to separating particles

A CSIRO-developed tumbler may be the answer to the costly problem of blocked screens in minerals processing.

  • 9 January 2008 | Updated 14 October 2011

CSIRO’s research into the important area of dry process granular separation has seen the development of the Rotary Classifier.

Now on the path to commercialisation, the CSIRO Rotary Classifier has application to several industries, but it has particular relevance to a problem in minerals processing.

An industrial problem

Mining industries typically separate minerals for processing using screens up to three by six metres in size. However, the holes in the screens often become blocked – known in the trade as blinding.

Blinding reduces the operating surface of the screens and causes downtime while the screen is unblocked.

CSIRO’s solution

CSIRO developed a system, called a Rotary Classifier, which separates granular material by tumbling it in a tilted vessel at various speeds.

As the material tumbles, small, high-density particles move towards the centre, and larger, less-dense particles move radially outward, allowing different materials to be extracted at selected locations.

CSIRO’s Rotary Classifier is:

  • fully automated
  • stable
  • consistent in terms of size and density segregation.


The Rotary Classifier’s ability to process large volumes on a much smaller footprint than traditional screens is also a drawcard.

The technology has been successfully tested with the coal and mineral sands industry.

Advantages of the Rotary Classifier over conventional screens include:

  • using less water and energy
  • ability to do dry processing
  • processing large volumes on a much smaller footprint
  • reduced processing time.

Partnering with industry

RCR Tomlinson Ltd, a Western Australia-based mining equipment company, is working with CSIRO to test the technology and look at opportunities for its commercialisation.

They plan to build one, possibly two, pilot plants.


Industries where this technology could be applied include:

  • minerals
  • grains
  • construction
  • chemicals.

The reduced reliance on water means this technology could be of great benefit to the iron ore industry, where it is common for there to be limited or no water available.

Learn more about CSIRO’s work in Fluid Dynamics.