# New kind of solution for extracting gold from e-scrap found?



## Finn from Ecuador (Feb 11, 2016)

Dear Sirs

I got this link from another forum where this article was causing confusion.

According to what i have learned from here there are strange details in the article, maybe it's just the reporter, but it comes from university chemistry team anyway.

http://words.usask.ca/news/2016/01/29/gold-diggers/

You are the specialists, what do you say?

Salud

Finn


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## g_axelsson (Feb 11, 2016)

The only thing they tell is that they have a new revolutionary method to dissolve gold based on vinegar. That's not enough information to comment on.

Göran


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## rickbb (Feb 11, 2016)

I've found that anytime someone spends all their time talking about how great their new discovery is without ever saying what this discovery is, is just selling you a bag of hot air.

If it works then prove it. If you can prove it you won't need to waste any time on selling it.


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## galenrog (Feb 11, 2016)

I read this a few weeks ago. The article offered no useful information, except that the process, which was not defined in the article, works in a small scale, controlled, laboratory environment. 

Will it work in a large scale field environment? Will it be economical? What will be in the waste stream? 

There are more unanswered questions. They may have something here. It took time and a lot of work for sodium cyanide to replace sodium hypochlorite for leaching ores, and we are better for it. Time will tell on this one, too.


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## Loito (Feb 18, 2016)

Hi, 

I found this YouTube Video about the process. The uploader is one of the postdocs I guess. I also searched for a publication or paper, but did not find something. One additional Information I found out was, that they use concentrated vinegar (acetic acid), a small amount of oxidant (maybe simple H2O2) and another acid (maybe HCl to form a chloro complex). To recover the Gold they use zinc powder.

https://www.youtube.com/watch?v=Wqql-5S8dm4


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## g_axelsson (Feb 18, 2016)

I did some digging but the only thing I could find was a five year old patent, http://www.google.com/patents/US20120228151 where the guy is among the patent holders.
If they are going to license the technology then they need a patent, unless they realize it would be impossible to get a patent and is trying to lock people up contractually before realizing the truth.

I must say that their aqua regia in the movie was not impressive, 5 minutes and the surface gold plating was hardly touched. And as usual the academic chemistry world have no idea of how gold reclamation from electronic scrap is done today. I haven't heard of any major refinery that uses aqua regia for recovering gold from gold plated circuit boards. That is what we usually call "Making a mess" on this forum.
Another critique of that process, how many refineries have the luxury of running unpopulated circuit boards? Gold in electronics is only partly visible, gold dissolved in solder and as bond wires in ic:s is a major part of the gold content.

But it would be a nice process for that gold plated scrap we all have lying around and an alternative to the sulfuric cell. I would use it on all IDE connectors I have..

Göran


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## fpower60 (Feb 19, 2016)

Hi everyone there! this is from university we just have to find the doc report on saskatchewan university http://artsandscience.usask.ca/chemistry/


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## tucsonarizonan (Mar 27, 2016)

That granular white thing at the bottom of the video looks like OxyClean (sodium carbonate peroxyhydrate) which is a source of peroxide. Anybody willing to experiment? I don't have a source of concentrated acetic acid.


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## patnor1011 (Mar 27, 2016)

I hope someone will figure out what it is. 8)


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## rickbb (Mar 29, 2016)

Hmmmm, acid plus peroxide dissolves gold, now where have I heard that before?


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## pp2kr (Jul 14, 2016)

Hello all
I tested a solution like you discussed here.
5ml Acetic acid+5ml H2O2(30%)+1ml HCl. It worked to leach gold foils from pcbs(at 60ºC). No sucess from CPU pins. I think the copper is begin attacked by the solution.

I need to make some tests here but this lecture head me to start chemistry bacharelor course.


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## nickvc (Jul 15, 2016)

Gold will go into solution if there is HCl and an oxidiser present but to get good dissolution you either need to remove the base metals first or dissolve everything.
With nitric as the oxidiser you can dissolve most, but not all metals, with the other oxidisers you need small particles for most of the metals to dissolve again certain metals cause problems.
The forum has dedicated countless hours discussing just about every known method or process and nothing new seems to have appeared, what is written here on the forum is about as good as anyone is going to get and the basic principle we work to is to remove the base metals first and then refine the values the only other methods involve leaches which target just the values which can be hazardous or very complicated chemistry, well for me, new leaches are been investigated but so far few seem very promising most seem to have a few glitches that are difficult to overcome, perhaps someone will discover the new process that actually works and if they do you can guarantee it will be discussed here at some point.


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## kurtak (Jul 15, 2016)

nickvc said:


> Gold will go into solution if there is HCl and an oxidiser present but to get good dissolution you either need to remove the base metals first or dissolve everything.
> With nitric as the oxidiser you can dissolve most, but not all metals, with the other oxidisers you need small particles for most of the metals to dissolve again certain metals cause problems.
> The forum has dedicated countless hours discussing just about every known method or process and nothing new seems to have appeared, what is written here on the forum is about as good as anyone is going to get and the basic principle we work to is to remove the base metals first and then refine the values the only other methods involve leaches which target just the values which can be hazardous or very complicated chemistry, well for me, new leaches are been investigated but so far few seem very promising most seem to have a few glitches that are difficult to overcome, perhaps someone will discover the new process that actually works and if they do you can guarantee it will be discussed here at some point.



VERY well said Nick

Kurt


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## pp2kr (Jul 15, 2016)

I have found some information around these guys and theirs studies. Here is what I have collected around the web. Maybe a clue....

1- Investigating Acidified Organic Solvents for Gold Leaching Hiwa Salimi, PhD student, chemistry department, University of Saskatchewan Some water-miscible organic solvents including DMSO, DMF, methanol, ethanol, acetone and THF in combination with HCl and low concentrations of an oxidant such as H2O2 or HNO3 were investigated for dissolution of gold. THF showed the best results demonstrating that gold powder could be completely dissolved in 2 hours in 1 mol/L HCl and 0.1 mol/L H2O2. Increasing the oxidant concentration to 0.3 M shortened the leaching time to 30 min. No complete gold dissolution was observed for the rest of solvents even after 24 hours. Although a THF/HCl/H2O2 mixture showed a slower dissolution rate in comparison with aqua regia, the applied conditions are considerably milder which is highly promising for gold leaching on an industrial scale.

2-POSTER TITLE: Simultaneous Leaching and Solvent Extraction of Gold: an Alternative Technique to the Cyanidation Process for recovery of gold In the present work, both leaching and extraction steps were done simultaneously in which gold containing materials were treated with a mixture comprising of an aqueous phase containing low concentrations of HCl and HNO3, and an organic phase consisting of a water-immiscible organic solvent and novel sulphurcontaining ligands. The biphasic mixture increases the overall efficiencies of the gold recovery process over known methods in which these steps are conducted separately. More than 99.9% gold recovery has been achieved in only four hours using low concentrations of acid (1M HCl) and oxidant (0.2 M HNO3) at room temperatures. The method was found to be highly selective for gold in the presence of large amounts of transition metal impurities such as Fe, Cu, Zn and Ag. This new technique can be a strong alternative to the cyanidation process which can greatly simplify the whole gold recovery process. HIWA SALIMI University of Saskatchewan 

3-GOLD LEACHING IN ORGANIC SOLVENTS: SIMPLE AND MILDE REACTION CONDITIONS FOR FAST GOLD DISSOLUTION
Paper No.: 8827 
Author: hiwa salimi, university of saskatchewan 
Co-authors:
Hiwa Salimi, University of Saskatchewan
Loghman Moradi, University of Saskatchewan
Stephen Foley, University of Saskatchewan
Room: Ballroom, Convention Floor
Time: Monday August 24, 2015 - 14:35

Common water-miscible organic solvents including DMSO, DMF, methanol, ethanol, acetone and THF in combination with HCl and low concentrations of H2O2 were investigated for dissolution of gold. THF showed the best result demonstrating that gold powder could be completely dissolved in 1.5 hours in 1.0 mol/L HCl and 0.2 mol/L H2O2. No complete gold dissolution was observed for the rest of solvents even after 24 hours. The rate of gold dissolution was measured by dissolving gold wire in THF/HCl/H2O2 mixture. The rate of gold dissolution in optimised condition was 75 g m-2 h-1 at room temperature and significantly increased to 590 g m-2 h-1 by raising the temperature up to 60 oC. Although a THF/HCl/H2O2 mixture showed a slower dissolution rate in comparison with aqua regia, however the applied conditions are considerably milder which is highly promising for gold leaching in an industrial scale.


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## pp2kr (Jul 15, 2016)

Also from the same authors:

INOR 750: Acetic acid process: A viable alternative to cyanide and aqua regia for leaching gold from primary and secondary sources ( http://sandiego2016.acs.org/i/651144-computers-in-chemistry/224 )


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## pp2kr (Jul 15, 2016)

However I didn't get any article from these authors.... :? :? :? :?


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