Gravity Concentration at Campbell Mine
Operated by Placer Dome Canada Ltd.
J.A. Folinsbee and B. Hewitt
Presented at: Society for Mining, Metallurgy, and Exploration annual meeting
Denver, Colorado, USA - February 24-27, 1997
July 21st, 1998
The Campbell Mine is located on the north shore of Red Lake in North Western Ontario. This underground mine has operated continuously since 1949 and produced over 300,000 oz of gold each year from 1994 to 1996. Even though much of the property remains unexplored reserves are estimated at 4,500,000 tonnes grading 18 gpt gold.
Since its beginnings the Campbell mine has had a gravity gold recovery circuit. From 1947 to 1982 the gravity circuit consisted of jigs and mercury amalgamation. Concentrating tables were introduced in 1982 and in 1995 the circuit was changed, removing the jigs in favour of Knelson Concentrators to produce a refinable product.
Four weeks of test work with a KC-CD12 in early 1994 yielded recoveries averaging 48.8%, considerably more than the 30-35% recovery that the jigs were obtaining and the decision was made to go ahead with the purchase of two KC-CD30 units.
The two Knelson Concentrators were put online in January and February of 1995 and initially averaged about 40% recovery. After a period of refining the circuit operations, the Knelsons have averaged 50.17% recovery for the first nine months of 1996.
With the installation of the Knelson circuit the mill throughput was increased while still realising a 16% higher recovery in the gravity circuit.
- accounts for 50% of total gold recovery (over 150,000ozs/year). An increase of approx. 16% recovery over jigs
- has reduced gold deposition (locked up in scale) in autoclave from 1000 - 2100 oz/month to less than 500 oz/month.
- reduction of weekday gravity circuit labour by greater than 50%. Elimination of an overtime weekend shift.
- increase in mill throughput over pre Knelson period on top of an additional 16% recovery.
- less water use than original jig circuit
- potential for the elimination of the jig dewatering circuit including pumps and cyclones
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