Gravity Concentration Of Gold From Base Metal Flotation Mills

M. Ounpuu; Noranda Technology Centre
presented at: 24th Annual Meeting of the Canadian Mineral Processors January, 1992

November 20th, 1999

The Noranda Technology Centre, in cooperation with Noranda's milling operations, has been investigating the potential of gravity concentration of gold from base metal flotation mills. This paper outlines the pilot and plant testing conducted at three operations with distinctly different ore types; porphyry copper, complex massive sulphide and polymetallic semi-massive sulphide. Testing has been with the Knelson Concentrator which has proven to successfully recover fine gold in a simple, trouble free circuit.

This paper discusses in detail the preliminary sampling techniques which can be applied to determine if gravity concentration is applicable, the aspects of pilot and plant scale testing, the difficulties associated with determining a shift in gold balance and the pros and cons of producing a gravity concentrate. A number of case studies are also detailed and performance data of the Knelson Concentrator is provided.

"Fine (-100 mesh) free gold/electrum can be recovered by gravity techniques from the grinding circuits of base metal flotation mills. This gold generally cannot be recovered successfully from the flotation streams. The ratio of concentration for gold in a cyclone is an excellent way to quickly determine if gravity concentration is possible. If the gold is concentrating to the U/F then it must occur as a free gold bearing alloy."

"If the concentration of gold to the cyclone U/F is high then pilot scale testing can be skipped in favour of plant scale testing."
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