is this true

[tygue]

A less toxic and less expensive means of gold recovery from electronic waste is reported by a research team at the University of Saskatchewan. Stephen Foley, an associate professor in the Department of Chemistry, says that the team used acetic acid, which, at 5 percent concentration, is table vinegar. “We use a minute amount of an acid and an oxidant to finish our solution,” he says.
Stephen Foley have developed a process to extract gold from electronic scrap. Image source: University of Saskatchewan.
The solution, he says, is the greenest solvent next to water, so eliminates many environmental concerns that come with long-standing methods of gold extraction.
In this technique, the gold extraction is done under mild conditions while the solution rapidly dissolves gold. “Gold is stripped out from circuits in about 10 seconds leaving the other metals intact,” Foley says.
To highlight the improvement Foley’s solution presents, he says that it costs $1,520 to extract one kilogram of gold using
aqua regia and results in 5,000 liters of waste. With the researchers’ solution, it costs $66 to produce one kilogram of gold and results in 100 liters of waste that can be reused.
Another possible advantage over current recycling processes, he says, is that this solution is gold selective, meaning it dissolves only gold and not other base metals like copper, nickel, iron and cobalt, found in printed circuit boards.
The next step for Foley and his team is to move the process into large-scale applications for gold recycling from gold-

 

[g_axelsson]

Already discussed here, http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=23458

As often, new inventions comes from people not knowing how e-scrap actually is processed.
I doubt that any (except newbies) would use 5 liters of aqua regia per gram of gold extracted from e-scrap.
I've extracted 50 grams of gold with less than 15 liters of acid used up, and that was a learning period.... and triple refined. For large scale recovery I would opt for sending the scrap to a smelter.

Göran

 

[myfalconry76]

It didn't say what was being used as a oxidizer! And there is only one way to find out and that's to try it. Another question what is being used as a precipitent?

 

[Phishin_ca]

It didn't say what was being used as a oxidizer! And there is only one way to find out and that's to try it. Another question what is being used as a precipitent?

Kadriver did a video series on using salt and vinegar
http://goldrefiningforum.com/~goldrefi//phpBB3/viewtopic.php?t=22967

 

[pp2kr]

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.
->>> I have tried to exchange THF to acetic acid... need to make some aditional tests

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 )

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

 

[nicholas.dougal]

here is his stupid video proof that tells you nothing except that it appears to happen at room temp since hotplate is off

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

 

[nicholas.dougal]

okay so i read on one of the many other forums on this subject that zinc was used to precipitate the gold.

so ZnAu if we follow this backwards we arrive at 2Au(NO3)3 + 3Zn -----> 2Au + 3ZnNO3
so they are using sodium nitrate in the reaction most likely before to form the gold nitrate.

I haven't had chemistry in a long time, so I'm wondering if they aren't using highly purified vinegar (C2H4O2).
in a combo with Sodium Nitrate(NaNO3), Hyrdrogen Peroxide (H202), Chloroacetic Acid(C2H3Cl02).
it would yield Gold, Table salt, water, and more vinegar.

I don't know if this all checks out, if no one else is good with chemistry I'm just gonna try it lol.

The ingredients all are extremely cheap, and environmentally friendly, so it seems plausible.

 

[butcher]

Although nitric acid alone can oxidize gold, (without chlorides or another halogen in solution)-- you will not have enough gold in solution to cement with zinc to even be able to see it.
We normally say nitric acid alone has no action on gold.

C2H3Cl02
Note the chloride, now with nitric acid we have a weak form of aqua regia.