Precipitant for palladium

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Renaldas

Well-known member
Joined
Jun 16, 2009
Messages
99
Cant get sodium or potassium chlorate in my country. DMG is quite expensive. What else can I use for palladium precipitation?
 
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 ...
 
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
 
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.
 
Dry bleach, calcium hypochlorite, will also work. Add it in very small increments to the concentrated HCl solution of Pd and ammonium chloride.

Steve
 
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
 
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
 
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
 
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
 
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
 
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
 
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
 
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.

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

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?
 
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
 
lazersteve said:
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

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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