# Separation of zinc from gold



## Owusu

Hello all I need help, I used Merrill Crowle cyenide process to recover gold from an ore, I used zinc as a precipitator and after fluxing and smelting I get a grayish metal which was tested in the AAS machine. It came out with high presence of good, now my problem: am not able to recover the yellow gold from the gold zinc alloy please what do I do?


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## etack

Owusu said:


> It came out with high presence of good



If you can explain this it will help in directing your answer.

If good=gold than we also need to know what that % is.

If good=PM's we will need to know what they are.

If it is just gold and zinc straight to AR drop with SMB melt.

next time wash precipitate from drop with HCL and this will be taken care of then.

Eric


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## Owusu

etack said:


> Owusu said:
> 
> 
> 
> It came out with high presence of good
> 
> 
> 
> 
> If you can explain this it will help in directing your answer.
> 
> If good=gold than we also need to know what that % is.
> 
> If good=PM's we will need to know what they are.
> 
> If it is just gold and zinc straight to AR drop with SMB melt.
> 
> next time wash precipitate from drop with HCL and this will be taken care of then.
> 
> Eric
Click to expand...

Thanks Eric,
The gold reading from the AAS reading was 79% gold but the zinc wouldn't separate from the gold even With the introduction of flux and high temperature


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## etack

Dissolve in AR, precipitate, and melt.

Eric


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## Owusu

etack said:


> Dissolve in AR, precipitate, and melt.
> 
> Eric


Am in Ghana, how do I get the SMB? I have over 20kg of this alloy and can get more


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## etack

sodium metabisulfite=SMB

Eric


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## Owusu

etack said:


> sodium metabisulfite=SMB
> 
> Eric


I know thanks but i have checked almost all the mining chemical compoanies in Ghana but no one seems to know of it. Am ready to pay for even a sample and buy in bulk if needed. This is my Skype ID: owusu.boamah1 we can chart and I get to show you metal and help me get the sodium metabisulfite. Can hydrazine hydrate also work in AR for such a situation if YES how do I get to buy.
Thanks a ton


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## Marcel

Why not using nitric to dissolve the zinc, then AR the clean gold?
To precipitate, there are many ways, not only SMB. You can cement it f.i.


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## Owusu

Marcel said:


> Why not using nitric to dissolve the zinc, then AR the clean gold?
> To precipitate, there are many ways, not only SMB. You can cement it f.i.


Thanks Marcel but I used nitric acid and everything including the gold dissolved it's was out of the solution that the AAS meter read the high presence of gold. How then do I get the gold from the solution and what other precipitator can I use ?


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## Geo

SMB is a substitute for sulfur dioxide gas. if you can source this gas (which is a common gas) you can use it directly. sodium metabisulfite is a food additive, try sodium sulfite or sodium bisulfite.


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## philddreamer

> I used zinc as a precipitator


Owusu, you can use copper also as a precipitator, (cementing). If you have gold in solution, you can cement, like it has been mentioned. Take some clean copper and place it in the solution and the gold will cement out of solution. Mind you, your gold will have a bit of copper contamination. There are more detailed information in many posts; the search engine will help you find them.
Also, if you have a 79% of gold content, you best digest it in AR, like it has been suggested. You shouldn't try to run the alloy thru nitric, the karat, .790k, is too high. You should inquart with some silver and bring the karat down to about 6k, .250k, then the nitric will work dissolving the silver & zinc, thus leaving a gold sponge of about 98% to 99% purity. Then run the sponges thru AR for a higher purity. (If have melted the alloy into ingots, you need to melt it and make shot, this way the alloy will dissolve faster in the AR.) Run the shot thru AR, (HCl & Nitric). 


> I used nitric acid and everything including the gold dissolved


(Nitric alone will not dissolve gold... for the gold to dissolve, there must have been another chemical involved. 

Take care!
Phil


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## butcher

Gold will not dissolve in nitric acid (unless chloride contamination) as Philddreamer said above.

If this is a nitric solution using copper metal will cement anything of value from solution, make sure to use a large clean piece of copper (buss bar from electrical panels works well).


You can make your own copperas (FeSO4) ferrous sulfate crystals to precipitate gold.
If you can get sulfuric acid, and an old transformer (steel laminates), you can make ferrous sulfate (FeSO4) also called copperas which is very good for precipitating gold from a gold chloride solution, dilute the sulfuric to 10%, cut welds on transformer (separate copper from the iron) incinerate the shellac from the iron, cut the clean iron to small pieces, dissolve in the dilute acid, heat the solution to form nice green crystals, store in plastic container with lid to protect from oxidizing in air, wet crystals with few drops of acid to keep wet and slightly acidic this way the will stay green and active for precipitating gold, if they are brown from oxidizing in air they will not work to precipitate gold.
The crystals can also be used to test for gold in a chloride solution in a white spot plate or white plastic spoon pace a FeSO4 crystal add several drops of solution to be tested, a brown ring of precipitated gold around the ferrous sulfate crystal is positive for gold


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## philddreamer

I always use SMB, and I forgot all about the copperas! 
Thanks Richard!


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## nickvc

I'm a little late coming into this thread but my advice would be to rinse very thoroughly the precipitate from the cyanide solution,place in a beaker put into a good fume hood and use either hydrochloric or nitric acid, not both, to remove the zinc this should raise the quality of the gold to 90% plus, if you want fine gold then dissolve the recovered powders in either AR or hydrochloric and bleach, filter and precipitate with your precipitant of choice, this should yield a very high quality gold.
Be aware mixing cyanide with acid is deadly and gives no second chances, if you intend on working with these materials care and good extraction and scrubbing is essential!


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## Owusu

philddreamer said:


> I always use SMB, and I forgot all about the copperas!
> Thanks Richard!



Thanks guys but is it possible to have chloride contamination from a Merrill Crowle cyenide leaching process and how is it possible for the chloride to precipitate along the gold because like I said the the alloy dissolved in nitric acid, not forgetting that the nitric acid is highly concentrated.
Would you advice I continue using the zinc as a precipitator in the cyenide leaching process?


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## nickvc

Osuwu gold is not dissolved by nitric acid however strong, I suspect your material may contain no gold if all you have done is leach it in cyanide and drop it with zinc.


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## Owusu

nickvc said:


> Osuwu gold is not dissolved by nitric acid however strong, I suspect your material may contain no gold if all you have done is leach it in cyanide and drop it with zinc.



I am sure very sure because the samples were sent to the laboratory for further, first at Aglo gold Ashanti lab and the university of mines lab in Ghana, I can believe there might be an impurity or didn't do something right. We further took a sample of the pregnant solution ( gold bearing cyenide solution) and we had a reading of 24.896ppm
I got the ferrous sulfate so I will desolve in AR and and let you know the outcome
How can I add pictures or vidoes here so you experts can see what am talking about. The zinc turn very yellow after fluxing and smelting


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## philddreamer

> ...my advice would be to rinse very thoroughly the precipitate from the cyanide solution,place in a beaker put into a good fume hood and use either hydrochloric or nitric acid, not both, to remove the zinc this should raise the quality of the gold to 90% plus...


Nick, shouldn't the powder be incinerated BEFORE placing them in the beaker and adding the nitric or HCl? I know it doesn't take much heat to melt zinc, but incinerating the powders will get rid of any the traces of cyanide and, if gold is present, it will not dissolve.
Just a thought.
Phil


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## nickvc

Phil because the gold precipitate comes down in very fine form and is mixed with the zinc it's not easy to put a flame over it, similar to foils from AP, good rinsing and a decent hood and scrubber should suffice but always take care when mixing cyanide and acids, as I said earlier there are no second chances!

Owusu I'm still confused how all your precipitate dissolved from the cyanide leach, without hydrochloric or salts in abundance in the mix nitric will not dissolve gold, unless your missing something out in your description of your processes I'm dubious you have any. The process of leaching gold with cyanide is not new nor is the use of zinc to recover your values, it's well tried and tested and works so if all you did was to take your precipitate and melt it and then just add nitric you should still have visible gold in the bottom of your beaker, if you don't it wasn't there to start.


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## Owusu

nickvc said:


> Phil because the gold precipitate comes down in very fine form and is mixed with the zinc it's not easy to put a flame over it, similar to foils from AP, good rinsing and a decent hood and scrubber should suffice but always take care when mixing cyanide and acids, as I said earlier there are no second chances!
> 
> Owusu I'm still confused how all your precipitate dissolved from the cyanide leach, without hydrochloric or salts in abundance in the mix nitric will not dissolve gold, unless your missing something out in your description of your processes I'm dubious you have any. The process of leaching gold with cyanide is not new nor is the use of zinc to recover your values, it's well tried and tested and works so if all you did was to take your precipitate and melt it and then just add nitric you should still have visible gold in the bottom of your beaker, if you don't it wasn't there to start.



It beats my mind I would considered that the ore has no gold but we did fire assey test before starting the leaching process, we also took samples of the pregnant solution for test and it also came out very positive (mentioned the the values earlier) so am really worried but like u saying probably I missed something during the stripping the gold off the zinc. I will be going to the site, i will be very glad to share the pictures or videos with anyone interested, 
I will also be glade to get direction through the process till we get the gold. I don't mind paying for the service after we succeed this is my Skype ID: owusu.boamah1 I have spent too much on this and the prospects are so so high checking from the test results. 
I conducted a simple ore washing and mercury and we had gold but we know the mercury does not get enough gold so PlEASE don't give up on me
Thanks a lot


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## Labman

Those here on the forum are mostly scrap refiners that don't usually deal with gold ores. Halides and salts of halides do cause nitric acid to dissolve gold, but not just halides; chalcogens are oxidized to acid forms and can dissolve gold when strong nitric acid is involved, selenium is one of the worse. It's customary to use hot dilute sulfuric acid to remove excess zinc rather than nitric or hydrochloric acids. At 79% gold content, aqua regia or hydrochloric acid with chlorine or a peroxide will dissolve it better. Zinc/gold compounds are brittle and a complete alloy is formed. Zinc drops from cyanide solutions will almost always contain silver and some platinum group metals. Though platinum doesn't dissolve in nitric acid normally, if alloyed with a lot of silver it will dissolve. Sulfuric acid doesn't pose this problem. Use sulfuric.


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## RGJohn

Owusu said:


> Hello all I need help, I used Merrill Crowle cyenide process to recover gold from an ore, I used zinc as a precipitator and after fluxing and smelting I get a grayish metal which was tested in the AAS machine. It came out with high presence of good, now my problem: am not able to recover the yellow gold from the gold zinc alloy please what do I do?[/quot
> 
> I well know that I am just stupid so please accept that as a given.
> ----
> Why do you think that you have a zinc-gold alloy?
> Zinc is fluxed readily.
> When the precipitated gold and leftover zinc was smelted, it (the zinc) went into the glass or slag. Or up the chimney as zinc oxide.
> ----
> So, why do you believe the resulting 'grayish metal' is zinc or 'gold zinc' alloy?
> -----
> After a smelting types of operation, one obtains a button or if a larger operation, an ingot. In order to run AAS on same a certain portion would have to be digested and 'shot' on the AA. And one would have to have a specific tube and also standard solutions for calibration. You got all this?
> -----
> So I really have a fair number of questions and any further specifics would be much appreciated.
> Thanks in advance,
> John


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## goldshark

just wondering if there are any other fingers involved in the handling of the Zinc precipitates before they get to Owusa. Any way to do a quick strip of the Zinc precepts, then give them to him? Gold makes people do funny things.


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## Yggdrasil

goldshark said:


> just wondering if there are any other fingers involved in the handling of the Zinc precipitates before they get to Owusa. Any way to do a quick strip of the Zinc precepts, then give them to him? Gold makes people do funny things.


The latest reply was made in 2012, so I guess its resolved or forgotten.


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## goldshark

I see, whoops, sorry. Why is it popping up in the current forum highlights?


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## Yggdrasil

goldshark said:


> I see, whoops, sorry. Why is it popping up in the current forum highlights?


Maybe a forum feature?
It's good though, to refresh old threads from time to time.


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