What is the ore mineralogy of copper? Is it oxide or sulphide type mineral/s?

Hello - this is Todd Harvey from Global Resource Engineers

Can you answer a couple of questions on the process for me?:

1. What type of elution circuit are you using?
2. What are the main copper minerals?
3. Do you have assay data on how much Cu is being extracted?
4. What are your solution grades coming out of the leach circuit - Au, Ag, Cu, Fe - free/total cyanide, pH
5. What is your cyanide concentration target - in the circuit and in the tails?
6. Do you add cyanide stagewise or all in the first leach tank?
7. Is your carbon activity impacted by the copper - what does your activity profile look like in the CIP tanks and after strip/regeneration?

There are a couple of things to consider here:

1. Avoid mining the copper rich materials if possible - this may not be possible of course but certainly it would help - cyanide consumption would go down considerably and EW would be easier.
2. Adding cyanide stagewise in smaller concentrations can help reduce the driving force reducing copper dissolution and cyanide consumption.
3. Acid carbon washing does not generally reduce the copper prior to elution.  It actually can make it harder to elute.  A cold caustic cyanide prewash can remove the copper and this is a good option and you can install a small Cu EW circuit to remove the copper from the eluant and recycle it.  You may be able to use iron precipitation to remove the copper as well. I would recommend some simple test work to design a new wash procedure.
4. The adsorption of copper cyanide complexes on carbon is highly pH dependent.  If you can raise you leach/CIP pH at or above 10.6 your copper adsorption will fall dramatically.  You will now have dissolved copper remaining in solution that may have to be removed.

If you need more advice fee free to contact me.  I can help with test work, design etc...

Regards

Todd

I believe you could affect the copper in several stages. I published a paper in SMME preprint number 93-230 regarding control of copper in carbon adsorption and gold recovery circuits. In that paper it is described how cyanide addition in the adsorption circuit can force a large amount of copper off from the carbon, and also a 'cold cyanide strip' process of removing copper from the carbon, before stripping the gold and silver. Lastly the selective voltage control in electrowinning can reject copper in the deposition onto cathodes. Preprint # 93-230, Ttitle "Control of Copper in Carbon Adsorption and Gold Recovery Circuits - American Girl Mining Experience". I worked closely with an industry carbon expert, Rick Follis in making the plans and chemistry changes and accomplishing much copper reduction in the circuit.

Morning

Leaching: you need to change this ore to oxides by roasting(difficult) , maybe use washing by water ,Increase lime,blending with another ore by different ratio {you need make a lot of tests).

Adsorption: If you find a lot of copper in preg-solution and sent to carbon unit you can do {cold stripping) after finish from adsorption ..

REGARDS

MAte, I had a similar problem from Heap leach solutions. We had a Zadra circuit and found cold stripping the carbon on a first run and then standard hot strip on a second run eradicated a lot of the copper.