PILOT PLANT FOR NEW TECHNOLOGY SCREENING
17 April 2003 - CSIRO

The Rotary Classifier (for particle classification or sorting) overcomes the major problems of 'blinding' (where material jams the holes of industrial screens, effectively reducing the screen's operating surface), and constant wear-and-tear on screens from abrasive granular material.

Rights to develop the Rotary Classifier in the field of mineral processing, quarrying rock and sand industries have been taken up by the Australian engineering services company, RCR Tomlinson Ltd, of Perth, Western Australia.

The contract with CSIRO Energy & Thermofluids Engineering provides for a fast-track development of the Rotary Classifier into industrial-scale application.

RCR Tomlinson Managing Director, John Linden, says: "We were very impressed with the potential of CSIRO's Rotary Classifier to replace vibrating screens as the preferred method of classifying (sorting) mined ore and other materials of interest to the mining industry.

"Screens have never been an elegant way to classify material, with high wear rate and constant blinding. We see the Rotary Classifier as a technology to offer the market an effective, fast, low cost unit operation, and this makes it an attractive technology for commercial development.

"We hope to have a pilot plant up and running within two years and our research agreement with CSIRO provides for RCR to manufacture and sell the Classifier alongside our apron feeder and scrubber products".

"CSIRO estimates that the Rotary Classifier could, as a conservative estimate, have a market potential of up to $100 million in Australia alone, but there is still some work to be done.

"The focus of the development work will be a Rotary Classifier for continuous processing", Mr Linden says.

The inventors of the Rotary Classifier are Dr Guy Metcalfe and Dr Kurt Liffman of CSIRO Energy & Thermofluids Engineering.

Dr Metcalfe says: "The Rotary Classifier is more than just a separator. It has been designed to separate different materials, classify particles into groups by size or density, or it can be a highly effective mixer for different density materials".

The device comprises a rotary longitudinal tube with a fixed endplate functioning as an output for the device, with holes for extracting particles from the tube. The holes are placed at different radial positions depending on the desired sizes of particulate material to be extracted. One or several sized fractions can be removed simultaneously.

Dr Metcalfe says: "Successful trials of a prototype Rotary Classifier have been conducted on materials such as building sand, which showed very fast and accurate separation. Classification was complete after three revolutions at 2 rpm.

"These are extraordinarily good results and highlight the speed and cost savings just on the operating side, even before wear and tear and production downtime are taken into account".

Other industrial applications where the Rotary Classifier can provide improved screening and mixing are:

Coal/ash separation, for separating coal from silicates at power stations.
Brick and concrete recycling, for removing contaminants such as steel, plastic, timber and organics prior to use.

Mineral sands reduction, this is an application for running the Classifier in a mode where it mixes instead of separates, to solve the problem of undesirable segregation in the heating kilns used in the reduction process to produce, for example, titanium. Based on CSIRO research, if coal is ground to a particular size, dependent on the density difference between coal and titanium oxide, all the particles will mix well and the reduction will proceed more effectively.
CSIRO has patented the Rotary Classifier and has retained rights to applications outside the field of mineral processing, quarrying rock and sand industries.

http://www.csiro.au

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