Acid Peroxide and base metals.

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ItsaboutROI
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Acid Peroxide and base metals.

Post by ItsaboutROI » October 12th, 2019, 7:27 pm

so the Forum books indicates that it's best to dissolve the base Metals first before dissolving the gold and you can do that with acid peroxide. So my question is:

- if I had already made the mistake and recovered the gold along with other base metals in powder form can anyone confirm if I am right in assuming that if I add acid peroxide to the powder I should be able to dissolve only the base Metals & the powder left undissolved should be the gold is that correct?

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Re: Acid Peroxide and base metals.

Post by FrugalRefiner » October 12th, 2019, 9:17 pm

No.

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Re: Acid Peroxide and base metals.

Post by FrugalRefiner » October 12th, 2019, 9:24 pm

ItsaboutROI wrote:
October 12th, 2019, 7:27 pm
- if I had already made the mistake and recovered the gold along with other base metals in powder form can anyone confirm if I am right in assuming that if I add acid peroxide to the powder I should be able to dissolve only the base Metals & the powder left undissolved should be the gold is that correct?
I know my previous response was abrupt, but it was the simple answer to your question.

You "made the mistake and recovered the gold along with other base metals in powder form". I have no idea what that means. Did you precipitate with a reducing agent? Did you cement on copper or iron? Did you precipitate hydroxides by adding alkaline?

Since we don't know what you have, there's no way of knowing what adding "acid peroxide to the powder" might accomplish.

Give us some more information and we'll try to help.

Dave
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ItsaboutROI
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Re: Acid Peroxide and base metals.

Post by ItsaboutROI » October 12th, 2019, 10:32 pm

I apologize let me clarify it means that I didn't do the acid and peroxide before doing the HCI and bleach which means that the gold and the base Metals dissolved, Then they were precipitated with iron sulfate..

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Re: Acid Peroxide and base metals.

Post by Lino1406 » October 14th, 2019, 12:34 pm

Iron sulphate will not precipitate base metals

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Re: Acid Peroxide and base metals.

Post by ItsaboutROI » October 14th, 2019, 11:53 pm

Lino1406 wrote:
October 14th, 2019, 12:34 pm
Iron sulphate will not precipitate base metals
I was under the impression that iron will precipitate all less reactive metals below it as the oner's in the following chart..
main-qimg-95bdaaf1ad14b231371e1ff7caf01266-c.jpg
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Re: Acid Peroxide and base metals.

Post by Shark » October 15th, 2019, 12:09 am

Iron metal will drop everything below it, iron sulfate (commonly referred to as Copperas, ferrous sulfate or FeSO4) is fairly selective for gold. I use it quite often for dirty solutions.
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Re: Acid Peroxide and base metals.

Post by ItsaboutROI » October 15th, 2019, 2:19 am

Shark wrote:
October 15th, 2019, 12:09 am
Iron metal will drop everything below it, iron sulfate (commonly referred to as Copperas, ferrous sulfate or FeSO4) is fairly selective for gold. I use it quite often for dirty solutions.
Ah man, so the chart doesn't apply to copperas? Can anyone explain why.. I remember reading if you have base metals in solution they will drop too. Just trying to make sure i am understanding why things happen..

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Re: Acid Peroxide and base metals.

Post by Lino1406 » October 15th, 2019, 3:13 am

Redox potentials Fe++/Fe+++ (FeSO4), 0.771v
Fe/Fe++ -0.44v

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Re: Acid Peroxide and base metals.

Post by Shark » October 15th, 2019, 9:31 am

The little I know is that metal is a form of a substance such iron=Fe. What we call copperas is FeSO4 with the addition of 7H2O, or FeSO4 7H2O. Why it works the way it does has to do with the state the iron is in, such as a sulfate or oxide (oxidized state, for iron we commonly call it rust). Copperas gets the name from the color, not from the metal it is derived from, which is often confusing. Wikipedia has a pretty good page on it under iron sulfate II.

https://en.wikipedia.org/wiki/Iron(II)_sulfate

I am still trying to grasp the chemistry side of refining myself. It is a slow go for me but I keep beating at it.
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Re: Acid Peroxide and base metals.

Post by FrugalRefiner » October 15th, 2019, 9:59 am

Cementation works because a more reactive metal (in its metallic state), is willing to give up electrons to a less reactive metal that is in solution (in its ionic state). In the process, the more reactive metal goes into solution (becoming an ion), while the less reactive metal cements out in its metallic state.

In copperas, the iron is already in its ionic state. It no longer has electrons that it can easily give up to a less reactive metal.

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Re: Acid Peroxide and base metals.

Post by Shark » October 15th, 2019, 10:27 am

Well said Dave, Thanks. I wish I could put it together in words like that.
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Re: Acid Peroxide and base metals.

Post by g_axelsson » October 15th, 2019, 11:01 am

Everything in nature strives to minimize the energy content and even out the energy distribution (entropy). For example water flows downhill, heat moves from a hot place to a cold one... pure metals have a lot energy stored in them when it was smelted from an ore or extracted from another source. To turn it back into a compound often releases energy.
The more reactive a metal is the more energy it takes to break the bonds to other elements, for example oxygen and iron is easier to separate than aluminium and oxygen.

When we cement out metals from a solution, we use the stored energy in one metal to extract another. Copper going into solution releases more energy than it takes to turn gold chloride back into gold (same for PGM:s, silver and mercury) so that works for cementing values out of a solution. Metallic iron have a lot more energy stored than it takes to reclaim copper, gold or anything less reactive than iron and so on. Iron will cement a whole bunch of metals out of solution.

Copperas, which contains Fe2+ ions still have a bit of energy left going to Fe3+, enough energy to turn gold chloride back into gold but not enough to turn copper chloride back into copper. That's why copperas can selective precipitate gold out of solution.
Other chemicals that we use to drop gold from solution gives off similar amount of energy.

This is of course a lot simplified without going into a lot about enthalpy, Gibbs free energy, reaction kinetics, equilibrium constants... and so on, but it works as an explanation on how cementing works compared to precipitating gold out of a solution.

Göran
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Re: Acid Peroxide and base metals.

Post by ItsaboutROI » October 15th, 2019, 11:41 am

FrugalRefiner wrote:
October 15th, 2019, 9:59 am
Cementation works because a more reactive metal (in its metallic state), is willing to give up electrons to a less reactive metal that is in solution (in its ionic state). In the process, the more reactive metal goes into solution (becoming an ion), while the less reactive metal cements out in its metallic state.

In copperas, the iron is already in its ionic state. It no longer has electrons that it can easily give up to a less reactive metal.

Dave
according to this explanation. My understanding is copperas has iron with no ions to give up. Based on that i would think that nothing would precipitate..
g_axelsson wrote:
October 15th, 2019, 11:01 am
Everything in nature strives to minimize the energy content and even out the energy distribution (entropy). For example water flows downhill, heat moves from a hot place to a cold one... pure metals have a lot energy stored in them when it was smelted from an ore or extracted from another source. To turn it back into a compound often releases energy.
The more reactive a metal is the more energy it takes to break the bonds to other elements, for example oxygen and iron is easier to separate than aluminium and oxygen.

When we cement out metals from a solution, we use the stored energy in one metal to extract another. Copper going into solution releases more energy than it takes to turn gold chloride back into gold (same for PGM:s, silver and mercury) so that works for cementing values out of a solution. Metallic iron have a lot more energy stored than it takes to reclaim copper, gold or anything less reactive than iron and so on. Iron will cement a whole bunch of metals out of solution.

Copperas, which contains Fe2+ ions still have a bit of energy left going to Fe3+, enough energy to turn gold chloride back into gold but not enough to turn copper chloride back into copper. That's why copperas can selective precipitate gold out of solution.
Other chemicals that we use to drop gold from solution gives off similar amount of energy.

This is of course a lot simplified without going into a lot about enthalpy, Gibbs free energy, reaction kinetics, equilibrium constants... and so on, but it works as an explanation on how cementing works compared to precipitating gold out of a solution.

Göran
This explanation saying that copperas has just enough ions to give up that will precipitate the gold which is the 2nd least reactive metal seems to make sense..

Would platinum precipitate as well if its in solution since its less reactive than gold?

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Re: Acid Peroxide and base metals.

Post by Shark » October 15th, 2019, 11:57 am

There is whole education in those last few posts. Thanks for the simple explanations.
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Re: Acid Peroxide and base metals.

Post by g_axelsson » October 15th, 2019, 12:38 pm

ItsaboutROI wrote:
October 15th, 2019, 11:41 am
This explanation saying that copperas has just enough ions to give up that will precipitate the gold which is the 2nd least reactive metal seems to make sense..

Would platinum precipitate as well if its in solution since its less reactive than gold?
It's not only the number of electrons an atom can give off or accept, it's also a question of the energy level of the electrons. But now we are going into details.

If you cement out gold with copper for example, then platinum can also be cemented. The list is a bit deceptive as it looks like it's even steps between the metals, but that's far from the truth. Some metals is really close in reactivity while others are far from each other.
If you try to cement platinum with gold then... I don't know. It would probably take a really long time at least.

If you precipitate gold with for example copperas... then you have to look that up. When it comes to precipitating some metals close to each other, the environment starts to affect the outcome, as well as time. Temperature, concentrations, what metals or ions that is contained in the solution, pH... it all affects the outcome. Lazersteve posted a nice diagram with different solutions and which precipitant worked well, as well as what could co-precipitate.

My first big gold button had a lot of palladium as contamination. The gold was precipitated with SMB from a chloride solution and I learned a lot out of that. To master refining you have to learn how to work around problems like that.

The more you learn, the more you'll realize that you still doesn't know.

Göran
Visit the GoldRefiningWiki, an online refining encyclopedia.
It also contains an online version of the book "Refining Precious Metal Wastes" by Hoke.

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