# will ferrous sulphate drop the gold???



## batesy53

hey there

i am dissolving some cpus in 1 oz batches at the moment until i get this right.i am dissolving in AR 1-4 ratio,filtering a couple times,then adding urea an abit of warm water to the mixture..everything swt up2 adding the precipitant...i was told to use ferrous sulphate to precipitate the gold??will this work???how much do i add to a 1oz batch??how long will it take??do i need 2 dissolve it in warm water 1st?? 

any clues r greatly appreciated


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## NobleMetalWorks

Ferrous Sulphate will drop out everything in solution that is lower on the reactivity series, than Iron, ferrous sulphate is really iron. As gold is lower on the reactivity series table, it will precipitate out Au, but also everything else under Fe. Should you use it to precipitate Au? It really depends on what you have in solution, what you want to get out of solution, and what point in your process you are.

For reference look here for the reactivity series:

http://www.zephyrus.co.uk/thereactivityseries.html

There are many other people that know far more about this than I do, if one of you would like to fill in the rest of what I might missed so I can learn also, I would appreciate it. Or if I have posted anything incorrect, please correct me.

Thanks

Scott


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## Geo

ferrous sulfate is copperas.it is used to precipitate gold. many members use it to process their gold.


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## butcher

Copperas or ferrous sulfate is a very good gold precipitant, in fact many times I prefer Copperas for precipitating gold instead of using sodium metabisulfate. 

(Edit: I goofed the chemical I meant to say was sodium metabisulfite).  

Hokes book also uses copperas to precipitate gold, she even explains how to test for gold in solution using ferrous sulfate. 

I have not noticed any more base metals precipitating when using FeSO4 than I have from using SMB. In fact I would guess that SMB in excess would be more likely to precipitate copper than ferrous sulfate in excess would, especially if your gold solution was contaminated with copper.

Ferrous sulfate is a salt of iron (iron and sulfuric acid), but it does not act the same in a copper solution as the elemental metal Iron would react to precipitate the copper, the iron metal bar has all of its electrons to share and will give these electrons up to the copper in solution, so copper ions would convert to metal copper powder, the ferrous sulfate does not have excess electrons to share and so it does not precipitate the copper, so here copper and iron can be in solution together as ions.


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## NobleMetalWorks

butcher said:


> Copperas or ferrous sulfate is a very good gold precipitant, in fact many times I prefer Copperas for precipitating gold instead of using sodium metabisulfate.
> 
> Hokes book also uses copperas to precipitate gold, she even explains how to test for gold in solution using ferrous sulfate.
> 
> I have not noticed any more base metals precipitating when using FeSO4 than I have from using SMB. In fact I would guess that SMB in excess would be more likely to precipitate copper than ferrous sulfate in excess would, especially if your gold solution was contaminated with copper.
> 
> Ferrous sulfate is a salt of iron (iron and sulfuric acid), but it does not act the same in a copper solution as the elemental metal Iron would react to precipitate the copper, the iron metal bar has all of its electrons to share and will give these electrons up to the copper in solution, so copper ions would convert to metal copper powder, the ferrous sulfate does not have excess electrons to share and so it does not precipitate the copper, so here copper and iron can be in solution together as ions.



Butcher,

Thank you for the correction and explanation.

Scott


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## butcher

Scott, 
You are correct that it is the iron in the copperas that precipitates the gold, here is something else to consider, if you have gold and platinum in solution, ferrous sulfate will precipitate the gold but not the platinum (platinum is below iron in the reactivity series), if we added a bar of elemental iron to the solution of gold and platinum, the iron would give up electrons to both gold and platinum and precipitate both of these metals from solution.

The reactions of the metal and ferrous sulfate in these examples are different types of reactions.


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## NobleMetalWorks

After I read what was posted, after my post, I referred to my chemistry book, I wanted to understand the differences exactly. I really appreciate the clarification.

Thank you

Scott


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## batesy53

thank you 4 your posts at least i am on the right track now..is it better to heat the solution slightly after i hav added the ferrous sulphate???thanks again 4 the help


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## Harold_V

Heating is not a requirement, and, at least in some cases, can work against you. That is the case when precipitating with SO2 from concentrated solutions. 

However, there are instances where heat is required, such as using oxalic acid. 

Read Hoke. 

Harold


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## batesy53

thanks harold,so do i just leave it 2 do its thing for a little while???

thx
chris


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## tek4g63

Butcher, 
I hate to be this guy.



> Copperas or ferrous sulfate is a very good gold precipitant, in fact many times I prefer Copperas for precipitating gold instead of using sodium metabisulfate



You ment sodium metabisulfite, correct?

Just want to keep it accurate for new members. Please don't hate me.


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## maynman1751

tek4g63 said:


> Butcher,
> I hate to be this guy.
> 
> 
> 
> 
> Copperas or ferrous sulfate is a very good gold precipitant, in fact many times I prefer Copperas for precipitating gold instead of using sodium metabisulfate
> 
> 
> 
> 
> You ment sodium metabisulfite, correct?
> 
> Just want to keep it accurate for new members. Please don't hate me.
Click to expand...


Yes sir! You be right. You caught Butcher with a typo! It is indeed Sodium Metabisulf(*ite*) and NOT 
Metabisulf(*ate*!)


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## philddreamer

It was probably an echo from repeating "iron sulphate".

Now, I have a question. Should we then use iron sulphate for precipitating the gold out of dirty solutions, instead of SMB? 
Use SMB on "cleaner solutions"?

Phil


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## maynman1751

philddreamer said:


> It was probably an echo from repeating "iron sulphate".
> 
> 
> Now, I have a question. Should we then use iron sulphate for precipitating the gold out of dirty solutions, instead of SMB?
> Use SMB on "cleaner solutions"?
> 
> Phil



I would imagine so. It's not often that that man is mistaken! 8) 


I don't see that it would make a difference....or I don't get your logic!


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## butcher

You are very correct, I did make a mistake in my use of words, I meant to say sodium metabisulfite, (and not sodium metabisulfate), the endings in these chemical names are important as they contain differing amounts of oxygen and so they can react differently in solution.

Thank you for catching my goof, this also shows me your paying close attention and learning, and if I were allowed to use the wrong name for a chemical, some new member could think that it would work, or that we use that chemical when we do not, and not know I used the wrong name for that chemical, with chemistry and mixing chemicals and metals, using the wrong chemicals or chemical name, could become dangerous, I will post a correction to the post above in red.

Phil,

I think dirty solutions can be hard to precipitate from, no matter what chemical used, take the case of tin in solution for example tin is involved in electronics from the solder, when in a solution dissolved with gold, tin will reduce the gold, forming colloids in solution, these gold metal particles will not settle but become charged particles, and repel each other they will not combine, to precipitate, but keep each other in solution, they also have been reduced to metal gold particles (by the reaction with tin), so they have already have gained back their missing electrons, so adding a copper buss bar will not cement them or reduce them to metals (they are already reduced), these gold particles are already reduced to metal so stannous chloride will not test for gold in this solution, they are already gold metal particles so a chemicals will not reduce them, so we are stuck here, we cannot tell there is gold in this solution and we cannot precipitate the gold unless we can break the colloid, (high heat and raising acid content can help some here).


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## Geo

butcher said:


> You are very correct, I did make a mistake in my use of words, I meant to say sodium metabisulfite, (and not sodium metabisulfate), the endings in these chemical names are important as they contain differing amounts of oxygen and so they can react differently in solution.
> 
> Thank you for catching my goof, this also shows me your paying close attention and learning, and if I were allowed to use the wrong name for a chemical, some new member could think that it would work, or that we use that chemical when we do not, and not know I used the wrong name for that chemical, with chemistry and mixing chemicals and metals, using the wrong chemicals or chemical name, could become dangerous, I will post a correction to the post above in red.
> 
> Phil,
> 
> I think dirty solutions can be hard to precipitate from, no matter what chemical used, take the case of tin in solution for example tin is involved in electronics from the solder, when in a solution dissolved with gold, tin will reduce the gold, forming colloids in solution, these gold metal particles will not settle but become charged particles, and repel each other they will not combine, to precipitate, but keep each other in solution, they also have been reduced to metal gold particles (by the reaction with tin), so they have already have gained back their missing electrons, so adding a copper buss bar will not cement them or reduce them to metals (they are already reduced), these gold particles are already reduced to metal so stannous chloride will not test for gold in this solution, they are already gold metal particles so a chemicals will not reduce them, so we are stuck here, we cannot tell there is gold in this solution and we cannot precipitate the gold unless we can break the colloid, (high heat and raising acid content can help some here).



also keep in mind that these solutions will have a distinctive color, ranging from mauve to royal blue and even red.


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## philddreamer

Butcher wrote:


> I have not noticed any more base metals precipitating when using FeSO4 than I have from using SMB. In fact I would guess that SMB in excess would be more likely to precipitate copper than ferrous sulfate in excess would, especially if your gold solution was contaminated with copper.



The material that I process has little tin, & most of the base metals are removed when I run the material either thru HCl or nitric in order to get rid of most of the base metals. So, copper & a bit of silver are usually the contaminants present in my AR. That's why I asked if precipitating my first round of AR with iron sulphate would give a "cleaner" gold; so, then I run the gold thru AR a second time, then precipitate with SMB. It was just a thought.

Thanks!

Phil


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## Harold_V

batesy53 said:


> thanks harold,so do i just leave it 2 do its thing for a little while???
> 
> thx
> chris


The reaction, assuming you have eliminated nitric completely, is immediate. No wait time is required, and the change is visibly obvious in that the solution clouds immediately, and changes color because the gold is removed as a solution. The cloudiness that appears is the fine particles of gold that precipitate. 

We're a bit touchy (at least I am) on the use of trick substitutes of numbers for words. You will be well served to stop using the number 2 when you mean *to* or *too*. I get down-right unreasonable when folks do that. Here, where the use of wrong terms can spell the difference between success and failure---or danger and safety, we try to be very precise in what we say, and how it is said. None of us are perfect, but we do our best by eliminating contractions that may not be clear to some folks, in particular those who do not use English as a first language. 

Harold


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## butcher

Philddreamer,
Hoke’s book speaks of refining the second time using a different precipitant than you used the first time, she says it helps, I believe these may act slightly different on which metals may also precipitate slightly from the solutions, but I am not real sure of details?


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## philddreamer

Thanks Richard!
I remembered reading so, & that's why I asked. Maybe the iron sulphate first & on the second SMB. I'm going to give a shot on my next batch.

Phil


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## kjavanb123

SBrown said:


> butcher said:
> 
> 
> 
> Copperas or ferrous sulfate is a very good gold precipitant, in fact many times I prefer Copperas for precipitating gold instead of using sodium metabisulfate.
> 
> Hokes book also uses copperas to precipitate gold, she even explains how to test for gold in solution using ferrous sulfate.
> 
> I have not noticed any more base metals precipitating when using FeSO4 than I have from using SMB. In fact I would guess that SMB in excess would be more likely to precipitate copper than ferrous sulfate in excess would, especially if your gold solution was contaminated with copper.
> 
> Ferrous sulfate is a salt of iron (iron and sulfuric acid), but it does not act the same in a copper solution as the elemental metal Iron would react to precipitate the copper, the iron metal bar has all of its electrons to share and will give these electrons up to the copper in solution, so copper ions would convert to metal copper powder, the ferrous sulfate does not have excess electrons to share and so it does not precipitate the copper, so here copper and iron can be in solution together as ions.
> 
> 
> 
> 
> Butcher,
> 
> 
> hank you for the correction and explanation.
> 
> Scott
Click to expand...



All,

As far as the copperas precitpiating only gold and not copper from a Au/Cu solution, I have to disagree, since I had a solution from AP process for fingers, and percipitated using copperas and the it produced gray/black powder instead of expected brown powder, after ammonia addition and boil, it turned dark brown color, so some other metals must have co-precipitated with gold.

Regards
Kevin


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## butcher

I was not trying to say that no copper would precipitate from using ferrous sulfate when precipitating gold from a dirty solution loaded with gold.

I was trying to explain that I believe less copper would precipitate from the same solution if copperous was used as opposed to SMB.

I have not noticed any more base metals precipitating when using FeSO4 than I have from using SMB. In fact I would guess that SMB in excess would be more likely to precipitate copper than ferrous sulfate in excess would, especially if your gold solution was contaminated with copper.

I never said "copperas precitpiating only gold and not copper from a Au/Cu solution" as you assumed I was saying, when precipitating gold from dirty solutions you will get that dirt in your precipitatant, in this case precipitating gold from a solution loaded with copper you will precipitate copper with your gold, which ever of these reagents you use.

I was also not discussing using ferrous sulfate as a recovery method by using it to precipitate gold from a solution heavily contaminated with copper as with precipitating gold from a copper solution, I was discussing using ferrous sulfate to precipitate gold from a gold solution with minor copper contaminate in the gold chloride solution as in the refining process as opposed to the recovery process.


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## badran106

i saw that butcher is giving us information...i will read it later ....thank you man you are kind..


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## butcher

badran106,

Basically garbage in your gold solution you get garbage out.
Keep the garbage out of your gold solutions.
That way you can precipitate a more pure gold from solution.
:lol:


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## Anonymous

To back up Butcher on his post. Excess SMB at outset appears to makes the dropping of any copper in solution with the gold very much more likely.

We've tried using large quantities of SMB to take the Chlorine out of a solution without boiling it off, and it has usually (over 70% of the time) resulted in a "dirty drop," pulling down any copper left, with the gold.

I have no experience with Ferrous Sulphate so I cannot comment on that part.

Jon


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## steyr223

Hey guys
I have used in excess of 30 to 100 time
Smb for probely my first 25 drops 
Just for the record my gold has always been 98+%
So what do you consider excess smb
and what do you consider the amount of copper the extra
smb is dragging down.

One of my very first drops was from 
A/R and I remember putting in so much smb( way over
used nitric) about a 1/2 of a container of smb but my gold dropped :mrgreen: 

Thanks steyr223 rob


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## butcher

Why??


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## bswartzwelder

steyr223 said:


> Hey guys
> I have used in excess of 30 to 100 time
> Smb for probely my first 25 drops
> Just for the record my gold has always been 98+%
> So what do you consider excess smb
> and what do you consider the amount of copper the extra
> smb is dragging down.
> 
> One of my very first drops was from
> A/R and I remember putting in so much smb( way over
> used nitric) about a 1/2 of a container of smb but my gold dropped :mrgreen:
> 
> Thanks steyr223 rob



I am pretty certain it takes about 1.1 ounces of SMB to precipitate 1 ounce of gold from your solution. By dumping in excess amounts of any chemical, you are creating more waste which at some time will need to be dealt with. Just my humble $0,02 worth.


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## rickbb

Perhaps your gold would have been 99.7%+ instead of 98%+ if you had only used the minimum amount of SMB?


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## steyr223

rickbb said:


> Perhaps your gold would have been 99.7%+ instead of 98%+ if you had only used the minimum amount of SMB?



Yes yes but of course that's funny you
mention 99.7%+ because that's exactly 
what I get now :lol: 

I guess thats my answer

Butcher my friend
What can I say I'm a stubborn learner
it only took 9 HNO3/HCl reactions for me
To stop my use of excessive nitric acid.
That's after reading it from the first time

Thanks steyr223 rob


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## Richard NL

Dear butcher, the man that makes me have multiple Mozilla's open, with many tabs.
Because you make many good posts, all over the forum.
I usually check, check and an independent check.

Keep up the good work.

But:


butcher said:


> (platinum is below iron in the reactivity series)


is correct, but i think you meant gold in this instance.

In the reactivity series of metals (in aqueous solution), it is not always clear witch metal is above or below with gold and platinum (and sometimes lead).
http://tinyurl.com/levw387 
http://tinyurl.com/lqwa72z

A search on G.R.F, only a short message: that the two are so close together, it doesn't matter.

Please correct me if I'm wrong or made a mistake, i am still learning.
Best regards Richard.


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## butcher

Richard NL,
Both gold and platinum are noble metals and both are much less reactive than Iron.
Platinum is much more less reactive than gold.


I often make some mistakes in what I say, so it is possible I said platinum when I meant to say gold, I am not sure where I made the mistake if I did, but if you point it out I will try to correct it.


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## butcher

The only place I see where I mention platinum in this topic, I believe I used it correctly.

If we have platinum and gold in solution and we use copperas (iron sulfate) (ferrous sulfate).We can precipitate the gold leaving platinum in solution, the Iron sulfate will not precipitate the platinum, but will precipitate gold.
Gold and platinum are both below iron in the reactivity series.
Even though platinum is below iron and gold in the reactivity series.


Iron metal if added to a solution of gold and platinum in solution would cement both gold and platinum from solution.

These are two different types of reactions, in the latter (cementing out metals with a metal of iron), the metal Iron gives electrons to the platinum ions (and the gold ions, or any ion less reactive than the iron metal in the reactivity series of metals) as the Iron goes into solution as an ion.

The copperas (ferrous sulfate) is an ionic salt of Iron and does not react the same as the iron metal does in the chemical reaction (cementing with a metal), the copperas reacts with the gold chloride to form iron chloride, as it takes the place of gold in solution and reduces the gold to metal.
in the copperas reaction the Iron ion (cation) replaces the gold ion (cation) in solution.

With iron metal (cementing out the metals) it is electrons given up by the iron metal to both gold and platinum converting the ions (cations) of these metals to atoms of these metals with a full shell of electrons.Again these metals (Gold, platinum,copper...) are reduced to metals as the iron metal is oxidized to cations.

With copperas we would not reduce many of the metals below iron in the reactivity series, but will leave these in solution with platinum as we reduce the gold in solution to metal using the iron sulfate (copperas) (ferrous sulfate).

With a bar of iron metal we would reduce any metal below iron out of solution with the gold and platinum.


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## Richard NL

Dear butcher, first off all i want to apology for not making myself clear enough.



butcher said:


> Scott,
> You are correct that it is the iron in the copperas that precipitates the gold, here is something else to consider,


 new section


butcher said:


> if you have gold and platinum in solution, ferrous sulfate


(not metallic element Iron)


butcher said:


> will precipitate the gold but not the platinum (platinum is below ([stt]iron[/stt]) gold in the reactivity series),


 next section


butcher said:


> if we added a bar of elemental iron to the solution of gold and platinum, the iron would give up electrons to both gold and platinum and precipitate both of these metals from solution.
> 
> The reactions of the metal and ferrous sulfate in these examples are different types of reactions.


I think that you are busy with the next sentence involving iron.
Every sentence on his one is correct, but if you look carefully to the complete story.



butcher said:


> If you have gold and platinum in solution, ferrous sulfate will precipitate the gold but not the platinum (platinum is below iron in the reactivity series).


Ferrous sulfate is not elemental iron.

Please correct me if I'm wrong or made a mistake, i am still learning.
Best regards, and merry Christmas, Richard.


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## butcher

I am getting lost.

Iron sulfate (copperas, or ferrous sulfate, FeSO4) will precipitate gold.
2AuCl3 (aq) + 6FeSO4 (aq) --> 2Au (s) + 2Fe2(SO4)3 +2FeCl3
Here we get elemental gold as the iron sulfate (iron cation) exchanges places with the gold cation.
The Chloride anion giving up the gold ion (the gold becomes a metal solid), and taking the iron cation in the place of the gold ion, the gold ion is reduced to become a metal, the ferrous (iron ion) stays in solution as a newly formed chloride ion.

Ferrous sulfate (iron sulfate) is not elemental iron, (although it is iron in solution as a cation), and in this reaction will not precipitate platinum from solution.
Platinum would stay an ion in solution it will not give up its bonds with chloride as easily as the gold did (or with copperas) it is happy happy to stay in solution.

----------------------------------------------------------------------------------------
Cementing with iron metal.
With Iron metal we use the reactivity series of the metal to cement gold and platinum from solution, or any metal below iron in the reactivity series that happens to be in solution, iron donates electrons, to these metals in solution (below iron in the reactivity series), these metal Ions gaining these electrons from the iron are reduced to metals, those iron atoms that gave up their electrons are oxidized into solution as iron cations (iron chloride salts).
So here the iron will cement both gold and platinum from solution.

One reaction is more of a chemical reaction with an electron exchange.
The other is more of an electron exchange with a chemical reaction.

OK I am starting to confuse myself now.

Gold and platinum are both below iron in the reactivity series of metals. 
When precipitating gold with copperas the reactivity series is not that important, the chemical reaction is different(than with cementing the metals out of solution).

Platinum is below iron in the reactivity series of metals, (so are several other metals including gold) when cementing the metals from solution, were are depending on the reactivity and use the reactivity series, iron will give up electrons to these metals below it in series and cement all of them from solution including gold, platinum, cadmium, nickel, tin, antimony copper...

Basically these are different types of electro-chemical reactions
I am getting so confused I do not know where it begins or ends


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## Richard NL

Dear butcher,

Please sir don't get confused or lost.(I'm the new one,You are the professional).

It begins in one sentence:
" if you have gold and platinum in solution, ferrous sulfate will precipitate the gold but not the platinum (platinum is below iron in the reactivity series)"


After several hours rereading en checking everything.
One conclusion.

Yes i did make a mistake.
Your right I messed up, i am sorry to have taken up your valuable time.
Thanks for pointing out my flaw.
Thank you Butcher for the for the detailed explanation.

Sorry.  

Merry Christmas, Richard.
edit


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## butcher

Richard NL,

I am no professional, I am just learning like everyone else.

This is fact:
"(platinum is below iron in the reactivity series)"

But this fact has little to do with the reaction below:
"If you have gold and platinum in solution, ferrous sulfate will precipitate the gold but not the platinum"

The reactivity comes into play with platinum in solution with elemental metal Iron.
"(platinum is below iron in the reactivity series)"

I am not sure of the reaction but may look like this:
cementing platinum from solution with iron metal
PtCl6 + 2Fe --> 2FeCl3 + Pt (s)

Lets look at a aqua regia solution of gold HAuCl4, and palladium H2PdCl6, and platinum H2PtCl6.
Now we add ferrous sulfate (copperas), the gold is reduced to metal, the palladium is reduced to a lower oxidization state but stays in solution as H2PdCl4, platinum in solution is unreacted by the ferrous sulfate.
PtCl6 + FeSO4 --> No reaction
PdCl6 + FeSO4 + e- --> PdCl4 +Fe(+3) + 2Cl
HAuCl4 + 3FeSO4 --> Au (s) + 3 FeCl3+ Fe2(SO4)2 + HCl

I think the confusion came in, when I put that statement of Platinum being below iron in parenthesis, after the statement, that copperas would precipitate gold and not react with platinum in solution, I may have not said it in a way that you could easily understand what I intended to say.

No problem we are all here to learn, we just help each other learn.


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## Richard NL

butcher said:


> Richard NL,
> 
> I am no professional, I am just learning like everyone else.


If everyone else was sometimes a little bit more like you,(considering learning and giving explanations) goldrefiningforum would be very different.
In that respect you are a professional.


butcher said:


> This is fact:
> "(platinum is below iron in the reactivity series)"
> 
> But this fact has little to do with the reaction below:
> "If you have gold and platinum in solution, ferrous sulfate will precipitate the gold but not the platinum"
> 
> The reactivity comes into play with platinum in solution with elemental metal Iron.
> "(platinum is below iron in the reactivity series)"
> 
> I am not sure of the reaction but may look like this:
> cementing platinum from solution with iron metal
> PtCl6 + 2Fe --> 2FeCl3 + Pt (s)
> 
> Lets look at a aqua regia solution of gold HAuCl4, and palladium H2PdCl6, and platinum H2PtCl6.
> Now we add ferrous sulfate (copperas), the gold is reduced to metal, the palladium is reduced to a lower oxidization state but stays in solution as H2PdCl4, platinum in solution is unreacted by the ferrous sulfate.
> PtCl6 + FeSO4 --> No reaction
> PdCl6 + FeSO4 + e- --> PdCl4 +Fe(+3) + 2Cl
> HAuCl4 + 3FeSO4 --> Au (s) + 3 FeCl3+ Fe2(SO4)2 + HCl


Under "normal circumstances" everything is correct.
For example exceptions:
1 mechanical drag-down.
2 Iron sulfate will also precipitate platinum from a boiling hot solution if the pH±7.
In a hurry, after denoxing a unknown solution(still hot and perhaps unnecessarily), and thinking the precipitation is gold, while in reality it is platinum.
You will by going the wrong road to recovery.

(Highest precipitation of Pt2+ ore PtCl6 = pH±8.)



butcher said:


> I think the confusion came in, when I put that statement of Platinum being below iron in parenthesis, after the statement, that copperas would precipitate gold and not react with platinum in solution, I may have not said it in a way that you could easily understand what I intended to say.
> No problem we are all here to learn, we just help each other learn.


Absolutely true.

Please correct me if I'm wrong or made a mistake, i am still learning.
B.t.w. happy new year and wish you all the best.


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## butcher

If you adjust the pH of your solution to neutral or on the alkaline side you will also begin to precipitate base metals and I would say it would probably be much easier to precipitate platinum.

I thought we were talking about the normal precipitation of gold from a solution like aqua regia (not salt water, or caustic salt water).

Here I did mention where you could precipitate platinum with copperas at pH 7 (salt water) But in practice I do not see any reason someone would want to.
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=48&t=11945&start=120


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## Goldreallife

Hello every one , I'm a new here 
Does the ferrous sulphate drop pure gold or with other metals especially copper ? , and is the adding of ferrous sulphate will be by parts step by step or only one time in one add ? 
and how can I know when I should stop from adding ?
Thank you


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## Goldreallife

Hello every one 
I'm newbie here 
Just I want to ask what's the best , SMB or Fr Sulphate ?
And how I can precise the quantity ?
Another thing , is H2O2 can drop the gold in AR solution ?
Thank you every one .


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## FrugalRefiner

Goldreallife, welcome to the forum. Please try to keep like discussions in the same thread. The more information is spread throughout the forum, the more difficult it is to follow it.

Many prefer ferrous sulfate for dirty solutions.

Precise quantities depend on many factors like other metals in solution, oxidation states, etc. As a general "rule of thumb", expect to use a gram or so of either for each gram of gold. Add your reduction agent, mix well, allow to settle, then test the solution with stannous to see if you need to add more.

I'm not familiar with using H2O2 to precipitate gold.

Dave


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## g_axelsson

Yes, H2O2 can be used both to precipitate or dissolve gold. If I remember correctly it depends on pH if it is a reducer or oxidizer.

I read about it eight years ago so I don't remember the details any longer and I have only user hydrogen peroxide to dissolve gold, never to precipitate it.

Göran


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## Goldreallife

Thank you very much you are very helpful , thanks again


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## Lino1406

Ferrous sulphate with its associated water molecules - 4.5 g per 1g gold. SMB indeed 1g per 1g gold. Ferrous sulphate is more selective and not smelling


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