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How to recover low grade placer gold mine (3 replies)

Victor Bergman
12 months ago
Victor Bergman 12 months ago

I know of a placer gold mine with an average grade is 0.3 ppm (0.3 gram/tonne) and the reserve is 30 million tons. The mine located in remote area and we do not have sufficient water although we send a sample for Knelson company but the max recovery was obtained 32%. I am looking for a new method with low water consumption, it is highly appreciated if anybody can help me for this issue.

We want to process 5 million tons per year, approximately 700 t/hr. Refer to our size to grade distribution, 80% is under 19mm and 25% is under 50 micron.

12 months ago
JohnnyD 12 months ago

Knelson concentration the best process ,follow by GEMINI TABLES. you could recover 75% of the water, however 0.3 grs/ton is not high.

There is no dry process for this high capacity. The air jigging and air tables are for < 1000 tpd. However I agree that you may want to start the process with dry screening to improve the grade to be process, reduce the material weight and then the < 2mm to a Knelson line of concentrators (water recover system ), the gold tailings later (future) can be process at higher gold price.

John Koenig
12 months ago
John Koenig 12 months ago

Also have you considered a multi stage circuit, focusing first on recovery than on grade? This could be done with air jogs and air tables using no water at all. The main issue would be capacity, as they are generally lower capacity.

It also looks like you could do an improvement by dry screening at 6500 and discarding the coarse.

While a single air circuit of 700 t/hr is practical, using knelson or similar would require several machines and also multi-stage and or circuits to get good recovery and grade.

Using a air jigs or tables on a portion of the stream would reduce the over all water requirement.

12 months ago
JohnnyD 12 months ago

First to screen and reduce the weight for the value mineral, then is available a air classification for the -2 mm - 1 mm.(I do not know for 700tons/hr capacity, may be) Then Knelson of course many units for the high recovery of fines that the jigs or air table s would not be able. Finally since the recovery would be around 50% the gold tailings could be stock for future recovery. We tested on Kelsey jigs the recovery (up grading) the tailings of CN- gold.

In a gravity process , considering the recovery of water (75%) you still need as fresh clean water 1m3/tn of process mineral (around).

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