Modern Quarrying Q4 2019

AUTHOR: MUNESU SHOKO

ON PHOTO: FISHER AIR SEPARATOR A machine that effectively removes unwanted fines from abrasive and non-abrasive aggregate applications.

AIR SEPARATOR

How do you eliminate large amounts of unwanted fines in your material? Many aggregate producers face this problem. The availability of water for washing, and the environmental issues that accompany settling ponds, magnify this problem. Fisher Industries’ Air Separator technology provides much needed answers to these questions. A vailable as portable or stationary units, the Fisher Air Separator is a field-proven machine that effectively removes unwanted fines from abrasive and non- abrasive aggregate applications. Supplied locally by Dakota Mining and Quarry Equipment, the air separator in many cases eliminates the need for wash plants and has proven itself effective in limestone, granite, trap rock, sand and gravel applications. The Air Separator was first introduced in Africa in 2010. Howard Behrmann, CEO of Dakota Mining and Quarry Equipment, explains that the concept has been tried and tested in a number of commodities. In aggregate quarries, the Fisher Air Separator has been successful in removing unwanted fines in manufactured sand for asphalt. On a major SANRAL project in the Free State, with the lack of water for washing the FAS was instrumental in delivering in specification crusher dust to the asphalt plant. The removal of fines from the manufactured sand for concrete use resulted in a significant saving in water and cement in the final mix. Several companies in the local aggregate space have purchased the air separator. These include Raubex Bloemfontein, SPH Cape Town, Independent Quarries East London, Great Karoo Crushing, Blasting and Excavating, OMV Stilfontein, Afrimat Port Elizabeth, Lafarge Port Elizabeth and Dorning Crushers Kokstad. Applications and tests The unit has successfully been tested at Namakwa Sands for the WASHING OUT SUPER FINES – NO WATER NEEDED

KEY TAKEAWAYS

The principle of operation is simple and the unit has minimal moving parts

The operation involves introducing the feed material into a vertically rotating chamber where a rotating fan assembly creates a counter air flow

The outer wall of the chamber is constructed in a way that a counter current air stream can pass from the outside inwards. The rotation of the chamber also acts as a fan, generating the counter current air flow

When processing natural fines with the Fisher Air Separator, a moisture content of 3% or less will provide the best results. In processing crusher fines, the Air Separator will run effectively at 3-5% moisture content

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MODERN QUARRYING QUARTER 4 - 2019