Gravity Separation & Concentration Methods

Gravity Separation & Concentration Methods

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Optimize high-grade gold recovery with Falcon (1 reply and 1 comment)

P
hydrometallurgictest
2 months ago
hydrometallurgictest 2 months ago

Hello, good day.

I work on a project that we operate with ore with a high gold content. The circuit is composed of gravimetry (Falcon) being fed by the Cycloning Under and the Cycloning Over feeds the flotation and leaching circuit. Currently our global recovery is around 91% and 75 to 80% of this recovery comes from gravimetry (electrodeposition of the intensive leaching solution that leaches the gravimetry concentrate).

We sample feed, concentrate and gravimetry waste, and we assess that the gravimetry waste still has a high gold content. For example gravimetry feed fluctuates between 60-90g/t and waste fluctuates between 40-70g/t.

We currently operate with a 16-minute cycle, Falcon amperage of 28 to 31A, G-Force of 135g and process water flow of 15m3/h. I have the hypothesis that, with this high gold reject, the cycle time could be shorter as there is a possibility of gravimetric gold in the reject.

GRG tests will be carried out in the near future, but gravimetric waste samples were collected to be sent for testing on a benchtop Falcon and considerable recovery was still achieved.

I would like to know if a shorter cycle time can actually increase this global recovery even further? And does the high operating amperage help or hinder the Falcon's operation?

Best regards.

Mike
2 months ago
Mike 2 months ago
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While a shorter cycle time might reduce gold losses to tails, another issue maybe part of the cause.  This would be the efficiency of your cyclones.  The efficiency of cyclones is rather poor as compared to other classifying methods.  And with the trend to operate the cyclones at higher feed densities, this efficiency gets worse.  This means that the amount of fine material in the underflow increases, particularly of the higher gravity fraction.  The result is that you might have a significant amount of fine gold feeding the gravimetric circuit.  This could lead to larger losses.

There is probably not a low cost solution, but two things would probablu help; decrease the cyclone feed density (might require more cyclones and bigger pumps), or two staging your cyclones to give better performanc, in which the under flow is reprocessed, requiring another sump, pump and cyclone bank, but smaller than the primary.

P
hydrometallurgictest
2 months ago

Hi Mike, thank you very much for your response.

Our mine has ore with a very high gold content, high GRG and also fine gold associated with carbonaceous matter (high preg robbing). As a result, the cycloning stage here operates in a way that favors the vast majority of ore being reported to the underflow due to the high GRG, only fine material that is reported to the overflow for a flotation stage.

Falcon's feed has the following characteristic granulometry:
P(80) = 50#
P(45) = 100#
P(20) = 200#

As previously mentioned, bench tests were carried out with material from the tailings and flotation feed and material from the cyclone overflow. Only this test was carried out, obtaining around 38% in the Falcon feed, 32% in the Falcon reject and 3% in the cyclone overflow.

More tests will be carried out as soon as the benchtop Falcon returns to our unit. However, taking into account both the results of this test and the preliminary results of current levels, we believe that a shorter cycle time could be beneficial.

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