Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

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Cyanide Gold Leaching with Copper Present (4 replies)

T
Japan Man
6 years ago
Japan Man 6 years ago

Hello Everyone,

We are a small mining operation working out of Japan tying to maximize gold recovery with copper rich ore using cyanidation.

In a previous cycle of cyanidation we ran with 800tons of dust (gold tailings) we recovered 1.3kilos of gold after Elution, 94% purity. This is our best results ever after using lime to increase the pH and then ammonia to help remove the copper.

Now, we’re looking to improve recovery, as our carbon tests prior to Elution have shown 2kilos or more, but we’re still only getting a tad above 50%.

Chemicals used:

  • Sodium Cyanide 1.2tons
  • Activated carbon 1ton
  • Ammonia 75kg
  • Hydrochloric Acid 20litres
  • Ammonia Nitrate 50kg
  • Hydrogen Peroxide 20litres

And copper treatment chemicals which local engineers sell as “Copper Remover”

A. 475kg
B. 40litres

My question is: Since copper interferes with gold leaching, does anyone have a way to reduce or remove copper from the material prior to consolidation? 

How do we improve gold leaching in the presence of copper?

d
Cyanide
6 years ago
Cyanide 6 years ago
J
Jorge
6 years ago
Jorge 6 years ago

I think, you should review information on the SART Process, which has been used for some gold operations to minimize the effect of soluble copper. In this case the idea is to treat the PLS with sodium sulphide to precipitate the copper before the PLS is in contact with the carbon.

You should get a sample of carbon and determine the presence of precious metals and other elements (e.g copper). 

T
tesaygo1
6 years ago
tesaygo1 6 years ago

Hello Japan Man,

Me too was currently in a study how to maximize the recovery of gold in a gold-copper ore and tailing. I tested already using sulfuric acid leaching, ammonia bicarbonate leaching and ammonia sulfate leaching.

Base from my own observation ammonia bicarbonate is good for a oxide ore or tailing and ammonium sulfate for sulfide one.

Anyway i didn't yet try out ammonia nitrate. Maybe we can sharing information if you dont mind. And i also like to visit Japan either, maybe i can visit you their. Then what do you mean about ammonia ? Liquid or solid state?

Regards,

Jason Lee

J
Jorge Quintanilla
6 years ago
Jorge Quintanilla 6 years ago

Hello everyone:
I had that problem years ago and I solved it in several ways at the same time.
I had the CIP CIP CIC system, with modified ZADRA. The real problem was the copper build up in tailings dam return solutions and throughout liquids at the plant.
1st, the leaching pH was reduced to a minimum, taking very good care that it does not fall out. Under this parameter, the leaching of gold can be improved by depressing the copper leaching. pH 9.5.
2nd low concentrations of cyanide but without lowering them, in our experience was 250-300 ppm of free cyanide.
3rd The carbon also adsorbs large amounts of copper on its surface, so before the elution of gold, we performed copper elution with cold system, that solution was pumped directly to the tailings dam, after which the carbon was pumped to the usual system with temperature and pressure to extract the gold.
4th In the elution and electrodeposition of gold with the Zadra system, we lower the voltage and amperage to the minimum in the cells but with enough to deposit the gold, then the copper process should work with 10 volts and 1000 amps, we reduce it to 2 volts and 150 to 200 amp.
If there was still some copper in the gold precipitate, then we increased the amount of sodium nitrate in the fluxes to obtain the gold.
5th. In a way that I still can not understand, but we got it in luck, in a lab test and also in the plant,  we precipitated the copper return solution from the tailing dam with nitric acid. The problem is, in short time 5 to 10 min, the precipitate returned to its liquid state, therefore the key in the system was that we extracted the precipitate immediately from having appeared at the base of the tank, then the remaining solution had very low concentrations of copper 1 to 5 ppm being that before the system contained 600 ppm.

The precipitate was drained in gutters that dried with the sun and stored.

Sorry for my poor english


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