# COPPER SULPHIDE PROBLEMS



## REYMHO (Oct 31, 2011)

WE'RE PROCESSING GOLD ORES HERE, CYANIDATION THAT IS, D ORE ASSAYED 30% Cu CONTENT. WE NEED IDEAS FOR EARLY REMOVAL OF COPPER SULPHIDE, USING REAGENTS AND OR COPPPER DEPRESANTS


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## jimdoc (Oct 31, 2011)

REYMHO said:


> WE'RE PROCESSING GOLD ORES HERE, CYANIDATION THAT IS, D ORE ASSAYED 30% Cu CONTENT. WE NEED IDEAS FOR EARLY REMOVAL OF COPPER SULPHIDE, USING REAGENTS AND OR COPPPER DEPRESANTS



Why are you shouting?


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## Harold_V (Nov 1, 2011)

jimdoc said:


> REYMHO said:
> 
> 
> > WE'RE PROCESSING GOLD ORES HERE, CYANIDATION THAT IS, D ORE ASSAYED 30% Cu CONTENT. WE NEED IDEAS FOR EARLY REMOVAL OF COPPER SULPHIDE, USING REAGENTS AND OR COPPPER DEPRESANTS
> ...


Yep! Good question. 
This individual would be best served to edit his post, using both upper and lower case text, as is appropriate. Not likely to get any results this way.

Harold


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## Reno Chris (Nov 1, 2011)

It depends on what form your copper minerals are and where the gold is. You may be able to do a separating flotation, or you may do a pre-cyanide aeration and collect the bulk of the copper in the solution, or you may ship a whole ore concentrate off to a smelter. You have not really provided us with any detail, so its impossible to give a detailed answer with suggestions to look at.


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## Dr. Poe (Nov 9, 2011)

Wither you are leaching by vat or heap, you should keep your pH high (at least 11pH) , Keep all chlorides away from the cyanide as the deadly gas, cyano-chloride vaporizes at room temperature. However cyano-bromide doesn't vaporize until strongly heated and is much safer. Cyano-bromide picks up the copper sulfides faster. The activated carbon will collect copper, but will spit it out whenever a gold ion contacts it. Sometimes with heap leaches One just has to accept that most of the copper has to come out before goodly amounts of gold follow. The gold is in a cyanide or thiocyanide , but the copper is really in the form as an alkali polysulfide. You might try pumping your solution through an activated carbon (coconut charcoal) for at a rate of ten minutes 
in contact with the charcoal, then run your solution through an electrolytic cell to remove the copper. You won't get any copper until gold starts to displace it from the charcoal. Be cautious if you are using peroxide to help with cyanidation as too much peroxide will destroy your cyanide. The optimum concentration of alkali cyanides is 5%. Going over this concentration causes the efficiency to drop. Loaded carbon is stripped with hot sodium hydroxide and the gold plated onto steel wool at 4 volts positive. Dr. Poe


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## Harold_V (Nov 10, 2011)

REYMHO isn't likely to read any of the responses---considering he has never returned to the forum after posting his comment. 

Dr. Poe,
You commented on keeping the cyanide level at 5% maximum, yet when I processed a gold complex ore, I kept the free cyanide at no greater than .2%----and oxidized with bromine. I kept pH at no lower than 10. I achieved a recovery of the fire assayed ore of greater than 99.55%. The ore assayed in excess of 300 ounces/ton in gold. Silver recovery was not good, but that wasn't an issue for the given circumstance. 

I had read that keeping cyanide levels quite dilute eliminates the problem of dissolving copper. Can you please comment?

Harold


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## Dr. Poe (Nov 11, 2011)

Harold
The gold yield graft with cyanides rises sharply from .15 to 5.25% but drops just as sharply and at 8% hits zero.
If you aren't willing to mine copper and silver with your leach, then you aren't getting the cupoaurite and aurocuprite. Electrum probably also is left behind. The high copper content of his ore promises to hide a lot of gold. The release of cyanogen gas, NCCN, is a real problem when cyaniding a copper based gold ore. As gold is combining with the cyanide, alkali is released and the pH will climb to 11. Gold within silver, tellurium (sylvanite, nagyagite, etc) may also be left behind.
If your ore assays at 300 troy per ton, why are you using such a slow method of leaching?
Dr. Poe


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## Reno Chris (Nov 11, 2011)

When I did a heap leach project in the early 1980s, we kept a concentration of half a pound of cyanide per ton of water (0.25%) and the pH at around 11.
These ranges are industry standard. 
We got good results on both gold and silver, but had only a little copper (a few ppm) in our ore.


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## Harold_V (Nov 12, 2011)

Dr. Poe said:


> If your ore assays at 300 troy per ton, why are you using such a slow method of leaching?


Not if. I still have the (third party) assays to support what I'm discussing. I would be unaware of any faster method, and considered myself very fortunate to have solved the riddle, as I had a responsibility to the owner. For the record, it was only four five gallon buckets of ore. 

The ore was provided to me crushed to ½"-. At that point in time, I had no clue what would be required to extract the values, considering I have no chemical education and worked as a machinist with nothing but a high school education. 

My refining venture, at that point, was nothing more than a hobby. I had no clue what was required to extract the values, and become aware of the vast majority being very finely divided only after viewing a piece of the ore under 400 power magnification. At that point I could see miniscule bits of gold spread through the matrix. Common sense told me that in order for the gold to be dissolved, it would require fine crushing, as the ore was quite sound---not oxidized in the least. 

I had already tried an experimental column, whereby I tried leaching the values without further crushing----using cyanide alone. Extraction was, at best, miserable. So bad that the follow-up assay showed a greater concentration than the head assay. I attribute that to the unusually high gold content, more or less the luck of the draw. The results of the column were abysmal. A small button of gold (which I still have) that weighed, at best, maybe 40 grains. 

Not having any guidance on the ore in question, I pursued some old mining journals and concluded that I had a complex gold ore----likely combined with tellurium (it was discussed as a mispickel ore). I noted that the use of bromine would serve to oxidize the values, so I tried that and enjoyed success. By that time I had built a ball mill and an agitation tank, each of my own design. I simply ran the ore until it no longer yielded values, at which time it assayed virtually barren. The ore spent about 145 hours in the agitation tank, as I recall. Could be wrong on that account. 

I consider the entire experience a grand success and a wonderful opportunity to learn something new. 

I would have benefitted by having a chemical education, but I had to work with what I had. 

Harold


Upon edit: Your comments on concentration levels of cyanide likely explain why I didn't enjoy great extraction of silver. While it's all very foggy for me now (this was processed in the very late 70's or early 80's), I recall that I had to maintain a narrow level of concentration of cyanide and pH in order for the use of bromine to be successful. Feel free to correct me if I'm wrong. Balance was so critical that it was required that I adjust pH down on more than one occasion, which I accomplished by the addition of small amounts of sulfuric acid (introduced to the agitation tank while it was in operation). 

Had I known that a higher concentration may have recovered the silver, I'd have tried that once the gold was extracted. We live and learn.


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## Dr. Poe (Nov 14, 2011)

In South Africa, cyaniding is done as "Carbon in Pulp". Where activated carbon is ground with the ore and cyanide and aerated.
The carbon is then separated from the spent solution by flotation. Carbon is very easily floated.
In this method the cyanide is never maxed out as the carbon keeps it fresh. Hot alkali strips the carbon and the alkali solution is electrowined. Dr. Poe


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