# Precipitant for palladium



## Renaldas (Oct 8, 2009)

Cant get sodium or potassium chlorate in my country. DMG is quite expensive. What else can I use for palladium precipitation?


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## jimdoc (Oct 8, 2009)

What country are you in? Somebody may be able to help you find a source if they know where you are.
Jim


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## Renaldas (Oct 8, 2009)

jimdoc said:


> What country are you in? Somebody may be able to help you find a source if they know where you are.
> Jim



Lithuania, European Union. There are ways of getting sodium chlorate, our chemical shops can make an order of several hundred kilos or even a tonn, no small quantities ... So I thought, maybe there are other precipitants for palladium ...


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## jimdoc (Oct 8, 2009)

Maybe you could make your own?

http://webpages.charter.net/dawill/tmoranwms/Chem_Chlorate.html

Jim


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## markqf1 (Oct 8, 2009)

Excellent post Jim,
I have been making small amounts of chlorate a little differently.
This process seems to be a little more advanced with better results than my own (ice bath) has produced.
I think I will try it.
I will let you know what I come up with.
Is this the process you use?

Mark


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## Irons (Oct 8, 2009)

Renaldas said:


> Cant get sodium or potassium chlorate in my country. DMG is quite expensive. What else can I use for palladium precipitation?



Any source of Cl2 is a substitute for Chlorate. If you add household chlorine bleach to HCl, it makes a good Chlorine generator.


SO2 will precipitate Pd.


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## lazersteve (Oct 8, 2009)

Dry bleach, calcium hypochlorite, will also work. Add it in very small increments to the concentrated HCl solution of Pd and ammonium chloride.

Steve


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## jimdoc (Oct 8, 2009)

Mark,
I bought what I am using now, but when I have to make, it I will.
It's good to keep info like this for when things get tough to find.
Jim


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## markqf1 (Oct 9, 2009)

Thanks Jim,
I like to make what I can.
Not only is it cheaper to do so, but it keeps me under "the radar". :lol: 

Mark


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## markqf1 (Nov 10, 2009)

Steve, Irons,
Does the calcium hypochlorite or bleach not work as good as chlorate?

Mark


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## lazersteve (Nov 10, 2009)

Mark,

Calcium hypochlorite works best when the solution contains HCl. 

The HCl and hypochlorite forms chlorine gas in situ.

The reason you use dry calcium hypochlorite is to keep the solution concentrated. Liquid bleach (e.g.: Clorox) is less than 5% hypochlorite and the rest is water which dilutes the solution. 

As you know PGMs don't precipitate well if at all from dilute solutions in most cases.


Steve


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## markqf1 (Nov 11, 2009)

Thanks Steve,
But I'm a little confused.
It was hcl/cl that I used to get it into solution.
I guess the addition of the nh4cl is what makes it precipitate it back out.
Right?

Mark


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## lazersteve (Nov 11, 2009)

Mark,

If there is enough left over free chlorine from the palladium dissolution, the solution is the right temperature, the right concentration, and you add ammonium chloride, the palladium will precipitate as palladium ammonium chloride. If platinum is present under the right condition it will co-precipitate with the Pd also. 

If you used clorox to put the Pd into solution then you most likely don't have a concentrated solution. This is yet another reason why I using zinc to precipitate the mixed PGMs out of HCl-Cl solutions before trying to separate them. If you try to concentrate the solution buy evaporation you'll get a lot of salt formation that will muck things up.

Once you've used zinc to precipitate out the black mixed PGM powder then you should use the AR process to do the final separations. Using AR directly on bulk low percentage yield scrap is more costly than HCl-Cl and zinc. 

Steve


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## markqf1 (Nov 11, 2009)

Ok Steve, thanks,
So just to make sure I got this right:
After cementing on zinc and redissolving in AR, I can use powdered hypochlorite instead of naclo3 to drop the pd after first dropping the pt with nh4cl ?

Mark


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## lazersteve (Nov 11, 2009)

Yes, of course after complete denoxxing, but you know that.

There is a post from one of the members here that I've been trying to find where I suggested this and it worked for him. 

Steve


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## Platdigger (Nov 12, 2009)

Mark, PM's sent.


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## markqf1 (Nov 12, 2009)

Thanks for the info guys.
I'm glad to know a new way.

Mark


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## Renaldas (Nov 14, 2009)

lazersteve said:


> Mark,
> 
> If there is enough left over free chlorine from the palladium dissolution, the solution is the right temperature, the right concentration, and you add ammonium chloride, the palladium will precipitate as palladium ammonium chloride. If platinum is present under the right condition it will co-precipitate with the Pd also.
> 
> ...



Thank you for information!
Can you say me, please, either platinum and palladium precipitate with NH4Cl both from concentrated AR solution after neutralizing nitric acid, or only platinum. I added a little NH4Cl to my AR solution, and orange cryslals formed. What is it?


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## lazersteve (Nov 15, 2009)

Renaldas said:


> I added a little NH4Cl to my AR solution, and orange crystals formed. What is it?



Most likely Platinum. The purer the precipitate the more yellow the color.

Steve


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## Renaldas (Nov 15, 2009)

lazersteve said:


> Renaldas said:
> 
> 
> > I added a little NH4Cl to my AR solution, and orange crystals formed. What is it?
> ...



But palladium is precipitating also? Can I be sure there are no more Pt and Pd in solution, or should I use another precipitant for Pd?
Crystals are bright orange in color.


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## lazersteve (Nov 15, 2009)

Do you have a photo of the orange powder you can post?

Steve


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## Harold_V (Nov 15, 2009)

Testing!

Why run blindly?

Dissolve a tiny sample in water, and test with stannous chloride. 

If you still have questions, test, also, with DMG. Test the same sample with stannous chloride after it has been tested with DMG. If there it platinum present, it won't be disguised by the palladium reaction because you will have precipitated the palladium with DMG. 

*READ HOKE! *

Harold


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## Renaldas (Nov 15, 2009)

Harold_V said:


> Testing!
> 
> Why run blindly?
> 
> ...



The solution contains a lot of gold, which is still not precipitated. Stannous chloride show black color due to high gold concentration. Maybe it would be wiser to precipitate gold first, not platinum and palladium?


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## Renaldas (Nov 15, 2009)

lazersteve said:


> Do you have a photo of the orange powder you can post?
> 
> Steve



I will post tomorrow, it is night in Europe now, and I do not have places with good illumination ...


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## markqf1 (Nov 15, 2009)

Drop your gold first.
Gold has a way of masking pt and pd with the stannous test if they are in solution together.

Mark


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## Harold_V (Nov 16, 2009)

Renaldas said:


> The solution contains a lot of gold, which is still not precipitated.


Not a problem. Do you have any ferrous sulfate? Even if you don't use it for precipitation, you should have a small supply on hand for testing in cases just like this. 

Take a drop of solution from your vessel, using a stirring rod. Place the drop in a cavity in a spot plate. Add a small crystal of ferrous sulfate. That should precipitate all of the gold, which will be evident by the formed brown powder, or even by a shiny skin of gold. 

Once the gold has been precipitated, you can then test the same drop with stannous chloride. With the gold gone, you can then read the test better. 

If, by chance, the remaining solution is heavy in palladium, you can eliminate the palladium by adding a drop of DMG. You can then test with stannous chloride for platinum. 

Read Hoke. All of this is well explained there, although you may have to dig it out, and you may have to draw some conclusions, using logic. That worked for me.

As far as I'm concerned, it's always smartest to precipitate gold before the platinum group. You can't wash the salts of the platinum metals without losing some to the wash. Also, the concentration level may be too low to precipitate, anyway. By eliminating the gold first, assuming you have enough of the platinum group to justify the effort, you can then evaporate the solution (for concentration), then recover that which will cooperate. 

I found it was generally better to just pour platinum solutions to the stock pot unless I was sure there was an abundance. That way they get concentrated so you can recover them in the future. 

Harold


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## lazersteve (Nov 16, 2009)

You must be 100% certain your solution is properly denoxxed before adding ferrous sulfate or ammonium chloride to any mixed gold, platinum, and palladium solutions. Below is an abbreviated list of some methods by which palladium will precipitate, *pay very close attention to the last two items in the list below:*



Standard Methods of Chemical Analysis said:


> Palladium Detection
> 
> ...
> 
> ...



From the above you can clearly see that precipitants behave very differently under different conditions. This is one of the difficulties when working with PGMs for beginners who tend to be in a hurry to get results. If you cut corners and do not properly treat your solutions prior to adding the precipitants you will end up with mixed metals and your refining efforts will be thwarted.

Steve


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## Renaldas (Nov 20, 2009)

lazersteve said:


> You must be 100% certain your solution is properly denoxxed before adding ferrous sulfate or ammonium chloride to any mixed gold, platinum, and palladium solutions. Below is an abbreviated list of some methods by which palladium will precipitate, *pay very close attention to the last two items in the list below:*
> 
> 
> 
> ...



Thank you!
Maybe it is better to use sodium sulfite for gold precipitation?

I get this after adding of ammonium chloride to my solution. Gold is still in solution.


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## Renaldas (Nov 20, 2009)

Lets look at this. I think, it is silver-palladium post and core. It dissolves in AR very slowly and after some time orange coloured substance can be obtained on the surface. What do you think, may it be silver-palladium alloy?


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## Harold_V (Nov 21, 2009)

Renaldas said:


> may it be silver-palladium alloy?


A simple test with nitric acid will reveal if it is, or not. Both silver and palladium are soluble in dilute nitric. Place one in a small container with a few drops of acid and water and heat. If the items are as you suspect, the resulting solution will be a dark grown, perhaps with a green highlight. A test of the solution with a drop of HCl (or some salt) will yield silver chloride. A test with DMG will yield a bright yellow precipitate if there is palladium. It will also react with stannous chloride, yielding various color reactions. Blue, green, or various shade of brown/black can be palladium. The best test is DMG, which will remove all doubts. 

Harold


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