# How long will gold stay in solution?



## Errol (Sep 20, 2017)

Hi all. New to refining.
I was wondering if I let my AR sit around with gold in it, how long will the gold stay in solution?


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## butcher (Sep 20, 2017)

When gold is dissolved in solution, it is no longer gold or atoms of gold in solution, so we actually do not have gold in solution but ions of gold in solution or a dissolved salt of gold in solution, this dissolved salt will stay a dissolved salt until some thing gives electrons to the gold ions through some type of reaction.

When we dissolve gold we are taking electrons from the gold atoms. When the gold atoms lose these electrons the gold is no longer gold atoms, but become oxidized gold ions in solution mixed with the other ions of the acid used to oxidize the gold originally, chloride ions.

The gold will stay in solution until something gives electrons back to the gold ions, this can be done several ways or with different types of reactions, electrolysis, replacement, displacement reactions, using metal or chemical reduction agents, even converting the gold salt to another type of gold salt, and with some metals (like silver) even light can act as a catalyst in the reaction.

How long will gold ions stay in solution?
Forever or until something give the ions electrons and they form atoms or some other salt.

Now on the other hand, we can have actual gold in solution as colloids or small clusters of atoms of gold with a charge, these small clusters are stunted in growth, and keep each other repelling around in solution, too small to settle by gravity, and polar charges keeping the solution in a motion pushing itself around.
Here you actually do have elemental gold in solution that will never settle out of solution, and because it is already reduced to gold atoms, it cannot be reduced chemically or by other means, the gold has all the electrons to fill its shells, so you cannot get this gold back out of solution by normal means chemically or electrically...


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## bigpagoda (Sep 20, 2017)

Would evaporation of a pregnant AR solution cause any problems? I have one that I used to test stannous that seemed to become syrupy so I just added some HCL to it. I was just wondering as it actually has a fair amount dissolved in it.


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## lanfear (Sep 20, 2017)

The only way to loose gold from a solution is to boil it or spill it


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## jason_recliner (Sep 21, 2017)

Great first question!

Putting gold into solution has even been known to _prevent_ its loss. https://en.wikipedia.org/wiki/Aqua_regia#History


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## Errol (Sep 21, 2017)

Thanks to all that answered


Does that mean if the gold is in "ion" state, it can evaporate?


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## butcher (Sep 24, 2017)

It depends, in ionic state gold is a salt of gold ions and chloride ions, much like sodium metal ions and chlorides ions make table salt NaCl. the gold salt in solution can be evaporated to a dry salt of gold chloride, as long as the temperature is kept lower than the vocalization point of the gold salt.

Evaporation can happen at lower temperatures there is no need to boil the solution, during boiling the fumes and gases can carry liquids as the bubbles of gases burst at the surface of the boiling liquid, this can splash or spit gold out with the fine mist, here our loss of gold is not from volatility of the solution, but from mechanical spitting of the liquid.

Keeping the solution temperature lower than boiling, and a watch glass to re-flux salts and gold stays in the pot.

The salts can be evaporated from solution, if the temperature is too high during drying of the salts we can volatilize the gold as smoke.
if we can slowly dry the gold without raising the heat we could drive the chloride off as gas and reduce the gold.
But this would not be easy to do without some loss of gold.

Here is where we do not want to incinerate a material with gold salts, if we must (like a solution or gold solution of purple of Cassius), a having a carbon source (like old filters) and using some sodium hydroxide may help to convert some of the gold, drive off chlorides, in an attempt to reduce the gold and rid it of chloride through evaporation, before the incineration process to keep from losing gold as much as possible, normally this is done with dirty solutions oe solutions with much base metals besides tin, like copper, the copper prefers to be a chloride over gold, here this can also be somewhat helpful, as the copper chloride can be heated to drive off chlorides, and not lose the reduced gold, as long as the temperature is kept low enough...

So it depends, gold in ionic state can go up in smoke, or we can reduce it to metal with control of the temperature and environment...


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