Nitric acid elemination

[sayf]

I read a comment made by lazersteve 10 years ago saying that eleminating nitric acid is to make a sellective precipitation process because if nitric is presented another precipitants will appear and he posted a chart explaining that
as an example, in a chloride solution, smb will precipitate gold and cucl but if nitric is presented also pd will precipitate, he didnt say that if nitric is presented no gold will precipitate!!
i was told that we eleminate nitric acid to make precipitation possible, in other words if nitric is presented gold precipitation will not happen
Am confused now, can any one give me a clear explanation please

 

[Lino1406]

Nitric acid is an oxidizer. Gold ion - an oxidizer, Palladium ion - an oxidizer. SMB is reducer, it starts with the nitric (if not eliminated), turns to gold, then to Pd, then to Cu++...

 

[sayf]

Nitric acid is an oxidizer. Gold ion - an oxidizer, Palladium ion - an oxidizer. SMB is reducer, it starts with the nitric (if not eliminated), turns to gold, then to Pd, then to Cu++...

I didnt understand any thing my good sir
Can u give me a clear detailed answer please
?

 

[sayf]

Please can any one give me a detailed answer and if lazersteve is right?!

 

[Yggdrasil]

Do you have a link from Lazersteve?
I think something has been lost in translation.
You need to destroy nitric in AR so that the metal do not redissolve.
Regards Per Ove

 

[sayf]

Do you have a link from Lazersteve?
I think something has been lost in translation.
You need to destroy nitric in AR so that the metal do not redissolve.
Regards Per Ove

Look at this link it will directly take u to the post and chart made by lazersteve and his explanation
I dont think i made any mistake translating his comment

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=6026&p=87562#p87562

 

[butcher]

Are you referring to the list Steve posted of using different reducing agents on different types of solutions containing the metals?

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=6026&p=87562#p87562

This is a list of reducing agents that can precipitate (or possibly precipitate under certain conditions) the different metals from a certain type of solution containing salts of these metals and salts of these acids used to dissolve the metals, it has nothing to do with the removal of an oxidizer before doing the precipitation of that metal using that particular reducing agent on the different types of solutions containing metals.

 

[sayf]

Are you referring to the list Steve posted of using different reducing agents on different types of solutions containing the metals?

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=6026&p=87562#p87562

Hey butcher glad for ur comment
Yeah lazersteve clearly said that the reason of nitric elemination is to avoid unwanted precipitates
He never mentioned that existance of nitric in the solution stops precipitating
Whats ur comment sir?

 

[butcher]

First I would need to understand which metal and which reducing agent you are discussing from the chart.

Oxidation is the removal of (or loss of) an electron from an atom of the metal, basically making a salt of that metal or an ion salt or compound of that metal dissolved in the solution.

Reduction is the giving back (or gain of ) that electron to form an atom of that metal with a full shell of its electrons.

In solutions using oxidizers like nitric acid to help remove electrons from a metal such as gold for example to make chloride ions of gold we cannot reduce the gold (change it back to elemental metal gold with atoms having full shells of electrons) or give the gold ions back electrons as long as the oxidizing agent (in this case nitric) is trying to remove electrons as our reducing agent is trying to provide them.

You need a better overall understanding of the chart and its meanings, it would be hard for me to discuss this as a whole as it is covering so many different reducing agents in so many different types of solutions, if you picked one type of solution and the metals involved it would be easier to explain that reducing agent and that type of ionic solution, and even discuss the oxidizer or oxidizing agent for that type of solution (or that metal).


Just as with other oxidizers like chlorine gas, we cannot use a reducing agent (like SO2) to precipitate a metal like gold from solution, when we have the oxidizer (or oxidizing agent) removing electrons as fast or faster than the reducing agent (like SO2) is trying to give back electrons, it like trying to dissolve and precipitate the metals at the same time with the poor electron not sure where to go and the atom gaining and then losing its electron in a game of ring around Rosie's pocket full of posies all fall down (but nothing precipitates as they all jump back up as the oxidizer take over again...

 

[Lino1406]

Poor elecron... that is good Butcher

 

[butcher]

Lino, I could never give as good of an answer as you can in a few words or few sentences.

With me only half understanding the question myself before trying to answer.

Here we are almost discussing two different subjects, the chart discussing the use of different reducing agents on different solutions to precipitate or not precipitate certain metals, and then also trying to discuss the oxidation or reduction potential of the solution (removal or using up of the oxidizer involved) or reducing the oxidation potential of a solution.

It would be better to discuss these topics about one reaction or solutions of metals, with one acid or oxidizing solution. Which has little to do with the chart or these reducing agents.

Maybe I am confusing myself now about what we are discussing, or what the question really is...

 

[sayf]

First I would need to understand which metal and which reducing agent you are discussing from the chart.

Oxidation is the removal of (or loss of) an electron from an atom of the metal, basically making a salt of that metal or an ion salt or compound of that metal dissolved in the solution.

Reduction is the giving back (or gain of ) that electron to form an atom of that metal with a full shell of its electrons.

In solutions using oxidizers like nitric acid to help remove electrons from a metal such as gold for example to make chloride ions of gold we cannot reduce the gold (change it back to elemental metal gold with atoms having full shells of electrons) or give the gold ions back electrons as long as the oxidizing agent (in this case nitric) is trying to remove electrons as our reducing agent is trying to provide them.

You need a better overall understanding of the chart and its meanings, it would be hard for me to discuss this as a whole as it is covering so many different reducing agents in so many different types of solutions, if you picked one type of solution and the metals involved it would be easier to explain that reducing agent and that type of ionic solution, and even discuss the oxidizer or oxidizing agent for that type of solution (or that metal).


Just as with other oxidizers like chlorine gas, we cannot use a reducing agent (like SO2) to precipitate a metal like gold from solution, when we have the oxidizer (or oxidizing agent) removing electrons as fast or faster than the reducing agent (like SO2) is trying to give back electrons, it like trying to dissolve and precipitate the metals at the same time with the poor electron not sure where to go and the atom gaining and then losing its electron in a game of ring around Rosie's pocket full of posies all fall down (but nothing precipitates as they all jump back up as the oxidizer take over again...

Thaats great butcher i got u, and i understand every single word u said
Lets take so2 or smb as a reducing agent
In the same row there are the types of solutions which are chloride sulphate and nitrate
As i understand the chart says when adding so2 to a chloride solution Au and CuCl will both precipitate
But when adding it to a nitrate solution Au and Pd will both precipitate and as he explained (not sure if i understand him well) if a mix of nitrate and chloride solution is made then the possible precipitates will be
Au CuCl and Pd
And the presence of CuCl in that mixed solution will also cause the Ag to precipitate also
Am i mistaken?
Lets make a cross section between the row that contains so2 and the coloumn that contains nitrate solutions we get in red words that Au and Pd are possible mixed precipitates
So does that mean that so2 will preciputate Au and Pd in a nitrate solution
Thats my question
Regards

 

[sayf]

Also and comparing what u said to what lazersteve said
Then he is mistaken in his comment here
He clearly stated that gold precipitation is possible in the presence of nitric acid
He said the purpose of nitric remiving is to make a sellective precipitation

 

[butcher]

Let's take SO2 or SMB as a reducing agent.
In the same row, there are the types of solutions which are chloride sulfate and nitrate.


As I understand the chart says when adding SO2 to a chloride solution Au and CuCl will both precipitate.

SMB is fairly selective for gold although (overuse of SMB or trying to precipitate gold form dirty solutions loaded with base metals like copper, the copper can also be reduced using SMB as a Copper I cloride salt).


But when adding it to a nitrate solution Au and Pd will both precipitate and as he explained (not sure if I understand him well).
Gold does not dissolve in a nitrate solution. So if gold is in a nitrate solution it is insoluble.




If a mix of nitrate and chloride solution is made then the possible precipitates will be
Au CuCl and Pd.

Not so. Here you are confused.
If a mix of these acids and metals were involved, we would need to eliminate the free oxidizer or free nitric acid (and eliminate nitrates if at all possible as to not give us problems later if adding acid to these salts later which can reactivate the salt back into free acid...) before we could reduce these metals from solution using SO2 to reduce metals or give them back electrons.
Now we only have a chloride solution (after removing the nitric acid) and now we can reduce gold selectively using SO2 gas, If the solution is fairly clean or low in copper contamination we can get a very clean precipitant of gold.
On the other hand, if the solution is loaded with copper or a dirty solution we can precipitate or drag down copper chlorides...
The Pd can be reduced from the chloride solution using a different reducing agent for the chloride solution...

And the presence of CuCl in that mixed solution will also cause the Ag to precipitate also
Am I mistaken?

Silver is insoluble as a chloride solution even in acids...

Lets make a cross-section between the row that contains so2 and the column that contains nitrate solutions we get in red words that Au and Pd are possible mixed precipitates
So does that mean that SO2 will precipitate Au and Pd in a nitrate solution?
That's my question

Gold is insoluble in a nitric solution, gold does not form a gold nitrate ion.

color=#0000FF]Indicated on the chart palladium can be reduced with SO2 gas from a nitrate solution, I have never tried it, but think I have heard it discussed on the forum.[/color]

 

[sayf]

Let's take SO2 or SMB as a reducing agent.
In the same row, there are the types of solutions which are chloride sulfate and nitrate.


As I understand the chart says when adding SO2 to a chloride solution Au and CuCl will both precipitate.

SMB is fairly selective for gold although (overuse of SMB or trying to precipitate gold form dirty solutions loaded with base metals like copper, the copper can also be reduced using SMB as a Copper I cloride salt).


But when adding it to a nitrate solution Au and Pd will both precipitate and as he explained (not sure if I understand him well).
Gold does not dissolve in a nitrate solution. So if gold is in a nitrate solution it is insoluble.




If a mix of nitrate and chloride solution is made then the possible precipitates will be
Au CuCl and Pd.

Not so. Here you are confused.
If a mix of these acids and metals were involved, we would need to eliminate the free oxidizer or free nitric acid (and eliminate nitrates if at all possible as to not give us problems later if adding acid to these salts later which can reactivate the salt back into free acid...) before we could reduce these metals from solution using SO2 to reduce metals or give them back electrons.
Now we only have a chloride solution (after removing the nitric acid) and now we can reduce gold selectively using SO2 gas, If the solution is fairly clean or low in copper contamination we can get a very clean precipitant of gold.
On the other hand, if the solution is loaded with copper or a dirty solution we can precipitate or drag down copper chlorides...
The Pd can be reduced from the chloride solution using a different reducing agent for the chloride solution...

And the presence of CuCl in that mixed solution will also cause the Ag to precipitate also
Am I mistaken?

Silver is insoluble as a chloride solution even in acids...

Lets make a cross-section between the row that contains so2 and the column that contains nitrate solutions we get in red words that Au and Pd are possible mixed precipitates
So does that mean that SO2 will precipitate Au and Pd in a nitrate solution?
That's my question

gold is insoluble in a nitric solution, gold does not form a gold nitrate ion.
Palladium can be reduced with SO2 gas from a nitrate solution, I have never tried it, but think I have heard it discussed on the forum.

Thanks for your time butcher i really appreciate ur help
I read hoke and did lot of searches
But that chart really confused my basics
Thanks again
Regards

 

[butcher]

Try doing the getting acquainted experiments with the metals and acids she discusses in her book, try some experiments on your own using the chart and its different solutions...

Try some experiments on your own with the oxidation potential of the solution and using the reducing agents...


Stick to what you understand about the basics, and continue to gain more understanding of them, then the chart will make more sense to you after you gain more of an understanding of how things work and why...

Please do not use texting lingo in your post, it makes something confusing even more confusing.

 

[g_axelsson]

Gold does not dissolve in a nitrate solution. So if gold is in a nitrate solution it is insoluble.

Actually, gold nitrate exists and it can be bought as a solid or as a water solution.
https://www.americanelements.com/gold-nitrate-13464-77-2
https://www.americanelements.com/gold-nitrate-solution-13464-77-2

Gold might not dissolve in pure nitric acid, but it will dissolve in a solution containing nitrate ions, for example aqua regia or poor mans AR.

Göran

 

[sayf]

Try doing the getting acquainted experiments with the metals and acids she discusses in her book, try some experiments on your own using the chart and its different solutions...

Try some experiments on your own with the oxidation potential of the solution and using the reducing agents...


Stick to what you understand about the basics, and continue to gain more understanding of them, then the chart will make more sense to you after you gain more of an understanding of how things work and why...

Please do not use texting lingo in your post, it makes something confusing even more confusing.

in the chart, in the row of ferrous sulphate and coloumn of chloride
It says that ferrous sulphate can precipitate Au and Pt
Between two bows it says (PH7 boil)
Does that mean precipitating Pt by ferrous sulphate needs to raise the PH of the chloride solution to 7 and boiling it right before precipitating ?
Also can i simply use tap water to raise the PH of the chloride solution?

 

[butcher]

Copperas will precipitate gold from an acidic solution (no need to raise the pH).

Copperas also has the benefits of being able to be used to test for gold in solution.

Ferrous sulfate works better than most of the other reagents for precipitating gold (like SMB) where there may be some traces of nitric left in solution the copperas can help to de-NOx the solution in the process by helping to decompose the nitric as it is used to precipitate gold.

Copperas can also be used to separate your gold from a solution containing platinum by being able to selectively precipitate the gold from a solution containing the platinum group metal.

From the chart, it indicates that by neutralizing the solution and boiling we can also precipitate platinum with iron sulfate, to me, this is kind of a moot point, as normally we have other and better means to selectively precipitate the platinum from the concentrated solution using different reagents such as ammonium chloride, and by neutralizing the solution and boiling we will also precipitate many of the other base metals in solution...


This to me, this information indicates a possible way of collecting traces of platinum from solutions, or more of a recovery method which could be used in a recovery purpose to get traces of platinum from a solution (like recovery from your stock pot) than being useful in a refining process...

 

[kurtak]

Also can i simply use tap water to raise the PH of the chloride solution?

Yes --- however that does not work well

Why ?

Because using water to change Ph of acid does not actually neutralize the acid - it just "dilutes" the acid

In order to dilute the acid enough to change the Ph of the acid by a factor of 1 you need to dilute the acid by ten times the starting volume of the acid

In other words - as an example - if you start with say 100 ml of HCl (Ph 1) to raise the Ph to 2 you need to add 900 ml water - then to raise the Ph to 3 you need to add another 900 ml water - & so on

In other words - if you start with 100 ml HCl - to get to a Ph of 7 you would need to add (about) 6,300 ml of water --- so you have increased the starting volume of 100 ml HCl to (about) 6,400 ml of "diluted" HCl --- in other words you are just diluting the acid - not neutralizing the acid - AND - it takes A LOT of water to change the Ph of the acid

On the other hand - when you use a base (like sodium hydroxide) you actually change the Ph by neutralizing the acid

When you do that - for each Ph factor of 1 - it takes 1/10 LESS of the base (hydroxide) for each change of 1 Ph factor

Example; - (note - these are not exact numbers - but the basic idea - actual numbers depend somewhat on the base used) --- so - say you have 10 ml HCl at Ph 1 - & IF - it takes say 10 ml of hydroxide to raise the Ph to 2 - then it will only take 1 ml hydroxide to get Ph 3 - & then it will only take .1 ml hydroxide to get Ph 4 - then only .01 ml hydroxide to get Ph 5 - .001 hydroxide to get Ph 6 - .0001 hydroxide to get Ph 7 --- which would mean you would only increase the original volume of the starting 10 ml acid to 21.1111 ml

Again - those are not exact numbers (because it depends on the "mole" chemistry of the acid/base you are working with) but the point is it takes MUCH less base to neutralize an acid from Ph 1 to Ph 7 - then it takes to change the Ph from 1 to 7 by "diluting" it

Kurt