# Palladium Precipitation Test: Comments and Questions



## lazersteve (Aug 18, 2007)

Here's where you can comment on the Precipitating Palladium Tutorial.

The tutorial is found here:

Precipitating Palladium Test


Steve


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## badastro (Aug 19, 2007)

Very interesting...

Have you calcined the red salt and made a palladium bead yet?


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## lazersteve (Aug 19, 2007)

Please understand that this segment was merely a proving ground for the larger reaction soon to follow. Now that I have demonstrated and learned the parameters that affect the reaction, I'll proceed to applying what I've learned to the mother liquor. 

For example, in practice I'll mix up a large batch of saturated ammonium chloride and apply it with my wash bottle. Also I roughly determined a good starting point for my additon of ammonium chloride per 50 mL of mother liquor.

This video is by not meant to be an exact method for larger scale precipitations, just a good solid foundation of the reaction principles.

I'll put the large scale precipitation video on the DVD when it's ready.

Steve


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## jimdoc (Aug 19, 2007)

Steve,
How long do you think saturated ammonium chloride solution
will last? Could you make a large bottle before hand to have
ready? Jim


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## lazersteve (Aug 19, 2007)

Jim,

Absolutely, since ammonium chloride is a stable salt it will keep indefinitely. You will need to make sure the bottle is sealed air tight when not in use to keep the water from evaporating. If the water evaporates just add enough water so that the solid ammonum chloride just dissolves again.

Steve


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## lazersteve (Aug 19, 2007)

Astro said:


> Have you calcined the red salt and made a palladium bead yet?



No, not yet. I'll calcine the salt after I precipitate the remaining mother liquor. The resulting BB from the red salt in the video is likely to be very small.

Steve


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## jimdoc (Aug 21, 2007)

Steve,
I dissolved a small amount of the palladium wire
that I got from organs and got a blood red solution
with nitric. My question is do I have to nuetralize
the nitric before I use ammonium chloride and 
sodium chlorate? Or do I dilute it? I am probably
going to add the 6 grams of tiny little wire from the
contacts also so I have some more to work with.
Right now there is probably a gram or less in solution.
I just want to see what the results are from pure
palladium before I try any scrap from electronics.
I also would like to make sure the palladium wire is 
pure, if it is it will be better to just keep it as it is or
melt it without refining it, do you agree?


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## lazersteve (Aug 21, 2007)

Jim,

The precipitation reaction should work with your nitirc acid solution. Harold or Chris need to confirm this one for me. I have only worked with Palladium in AP solutions. The Palladium Ammonium Chloride drop as the proper levels of ammonium chloride and sodium chlorate are reached in the solution. Concentrating the solution is still a requirement.

As a side note, the Palldium could be cemented from the solution using copper or silver metal once all the free nitric acid is removed via evaporation. I don't think the Pd from this method won't be as pure as that attained from the above reaction.

Steve


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## Harold_V (Aug 21, 2007)

I'm of the opinion that you should evaporate the nitric----but it's just that, an opinion. I am not basing it on any chemical knowledge, but I'd not be too pleased to work with the salt if it was contaminated with traces of nitric, which it will be. In spite of a fair amount of washing, it's pretty hard to totally eliminate almost anything that's combined with the salt, and palladium salts don't lend themselves to much washing without dissolving to some degree. If you were to ask my advice, I'd recommend you evaporate the solution. The choice is yours. 

I question that it will precipitate with nitric present------so if you give it a go without eliminating the nitric, I'd appreciate hearing the results. Hoke may have commented in that regard, but it's been too long for me to remember, and my copy is not available to me at this time. 

Do keep in mind that palladium won't precipitate from a dilute solution. This point can't be over stressed. The more concentrated the solution, the better the results. As I recall, Hoke calls for an ounce of ammonium chloride per ounce of palladium expected to be recovered, and an excess is advised. 

Harold


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## jimdoc (Aug 22, 2007)

Harold,
I have been using the smallest amount of nitric 
possible to dissolve the palladium. I just added
the 6 grams of contacts to that, and will see if it
is dissolved in the morning. If not I will add a little
more nitric, I am trying to keep it as full of palladium
as I can.
By evaporating do you mean heat it untill it is like 
syrup? If so how do I get it back to liquid without 
making it a dilute solution? Steve mentioned that 
the salts are water soluble. Do I add ammonium
chloride saturated water?, and then sodium chlorate?
With heat.
Thanks. Jim


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## Harold_V (Aug 22, 2007)

For starters, you'll have better luck using AR instead of straight nitric. Be careful if you started with just nitric----it's likely to come alive very quickly when you introduce the HCL, but that's what you'll have to do. You won't believe how quickly palladium dissolves that way. 

While I don't know that I can say what constitutes a good level of concentration, it wouldn't be out of line to expect a liter of solution to contain two, maybe three ounces of palladium. Think accordingly. When I refined gold, I'd generally run my concentration level up around four ounces/liter (when re-refining). 

You can have an abundance of HCL and not have problems. Keep that in mind. The worst problem it creates is that it can cause filter failure when too heavily concentrated. 

Fact is, one of the purification processes for further refining the red salt is to dissolve it in ammonium hydroxide, then re-precipitate it with nothing more than HCL.

It's hard for me to know what you have at your disposal, so what I'll do is tell you how I did the job-----and you can pick and choose methods that will lead you down the same path. 

Using an evaporating dish helps the process go faster, but I eventually moved away from them because I had limited burner space and could fit more beakers on the hotplate. Choose what works best for your case here. 

Evaporate the solution at a low heat----do not boil it----and do not allow vapors to come off that have color. Hold a cold object (a porcelain spatula works well) in the "steam" coming off to insure that only clear fluid condenses. As the solution evaporates, it will get darker and darker, eventually turning a blackish brown color, and thickening. It often will start forming a hard edge, but it's best that you not let it get that far, but if you do, it's not fatal. If in doubt, and it's gone too far, drip in a drop of nitric and a few drops of HCL, which will re-dissolve anything that may have gone too far. Don't go crazy with the nitric-----remember----you're trying to get rid of it. As it thickens and darkens, drip a few drops of HCL in the solution. When it's that concentrated, if you have free nitric, you'll see those familiar brown fumes come from the beaker. If, when you add the HCL, you see no fumes, and it's hot and very dark, you can stop the evaporating process at any time-----for the material in question is very water soluble. Dilute it enough that the acid is not heavily concentrated, and stop. You'll further dilute the solution when you wash down the filter. It helps to wet the filter well before you introduce any of the solution. Once fully filtered, wash the filter with tap water until you're happy with the amount remaining in the filter. If you try for a perfectly clean filter, you'll have added a lot of water, which can be troublesome when it comes to precipitation. The filter can be incinerated and values recovered later, so don't worry about leaving traces behind. You can also toss it in your stock pot and incinerate it with the recovered sludge. The values are not lost if you do things properly. 

If you find that your solution is too dilute, there's nothing wrong with heating it to evaporate water---just give it time to do so, and keep it clean, so it doesn't require filtration again. 

If you know your solution contains no platinum, if necessary, evaporate until it's quite dark again, then introduce the dissolved ammonium chloride (filter it if it's dirty). You can't recover the palladium when the solution it cold----it's done right under a boil. Heat the solution until it just starts boiling, then dribble grains of sodium chlorate in. Not too fast, they often boil up on you and can easily overflow the beaker. Scratch the side of the beaker with a glass rod if you don't see a change in color, and tiny specks of red salt starting to form. Sounds crazy, but they often 
seed where you scratch the beaker. Make sure the one you use is no more than half full, and work slowly with the sodium chlorate. Once you've seen it done, it will make sense and you'll have a general idea of what works, and what to avoid. 

When you introduce the ammonium chloride solution, if you have platinum present and it's in the right concentration, you get an instant cloud of platinum salts. It's a real fun thing to watch happen. Should you find yourself in that situation. allow the salts to settle well, then decant the bulk of the solution to another beaker, and filter the last bit, combining the solution with the decanted solution for precipitation of the palladium. 

From this you probably understand that when you have them both in solution, you recover platinum first, always, using this system. 

A tip on dissolving ammonium chloride. The reaction is endothermic, so requires heat to work. Start with hot water (tap water is fine) and use less than you think you'll need. Allow it to dissolve everything it will, and stir regularly. As the solution gets concentrated, you'll notice it is now cold. Stir a little longer to insure that it won't dissolve any more of the ammonium chloride, then you can pour off the solution and introduce a little more hot water to the remaining material. Do this until all of it has dissolved. By following this advice, you'll create a heavily concentrated solution, keeping the overall volume small. 

One more tip. An Erlenmeyer flask is cute as hell, but it will get you in trouble faster than any other container I can think of when you have a situation at hand that can boil over. There's no room for any expansion, so the slightest problem guarantees it will overflow. I'd suggest you not use them. 

Hope this helps.

Harold


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## jimdoc (Aug 22, 2007)

Harold,
Thanks, that helps me out alot. I plan on moving it
into a beaker when I work with it. I just have it in
the little flask because it started out very small with
one piece of wire. I added to that to hopefully make 
it enough to precipitate it back out. If all goes well
with this batch I plan on trying one of the palladium/plus
school rings to see what they are made of, I also got
a precium school ring that is supposed to be 25%
palladium/75% silver. I am hoping the palladium/plus
is mostly pd with a little ruthenium. 
Jim


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## Harold_V (Aug 22, 2007)

It stands to reason that you'd avoid what I said about using HCL (AR) if you get involved with an alloy that contains silver. You'd find yourself in the same position as when trying to dissolve gold that has silver within, whereby the silver forms a hard crust of silver chloride and the action coming to a stop. I should have been a little more specific. 

In such a case, you may find yourself having to deal with silver chloride. Otherwise, it's hard to separate the silver from the palladium. Once dissolved, you'd precipitate the silver as a chloride, then wash the palladium out with ample water. It's a lot of work, but I don't know of another way to separate the two. It's not even a good idea to do it in a silver cell because the ratio of palladium to silver is too high and that creates problems in the cell. 

I've been through this exact thing when processing sludge from a silver cell, where you have a high percentage of silver mixed with other values, so if you'd like to talk about it, feel free to ask. No sense me going on about it if it serves no purpose. 

Harold


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## jimdoc (Aug 22, 2007)

Harold,
The wire from the organs is pure palladium.
I added AR to that solution and it disolved the
rest of the contacts. I used your calculations
for the volume, and transfered it to a clear
pyrex coffee pot, that should make heating
easier. I will probably do it tomorrow, following
your directions as the weather will be nicer
tomorrow. Today I did a batch of processors in
poormans AR, so today was a gold day, and I 
made up some saturated ammonium chloride 
and put it in a wash bottle to be ready to do the 
palladium precipitation.

The rings I know are a different story, I shouldn't
confuse the topic by bringing them into it like I
plan on doing the same thing with them.
I planned on using straight nitric for the precium
ring as that is 75% silver, as I know the silver
will cause problems, although isn't it inquarted
by being 75% silver already? If I drop the silver
out as silver chloride with salt, that should leave
me with the pd in the nitric solution. Could I just 
save that as my standard palladium test solution?
I still need to save some gold as a standard to test
my stannous before using, I have been making it
up when needed.

The palladium/plus rings are unknown alloy, but 
I am thinking they are 90% or 95% palladium with 
ruthenium or maybe silver. These I plan on trying 
AR with. I will try one first before I do any others 
as a test. 
Thanks. Jim


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## Harold_V (Aug 23, 2007)

jimdoc said:


> although isn't it inquarted by being 75% silver already?



In a sense it is, but palladium requires no inquartation under normal conditions. If you had a batch of nothing but impure palladium that was contaminated with a trace of silver (solder, perhaps), you'd be able to dissolve it directly in AR, or even nitric if you don't mind it working slower. 



> If I drop the silver out as silver chloride with salt, that should leave
> me with the pd in the nitric solution. Could I just save that as my standard palladium test solution?



It would work, but you're working with an unknown solution. When you build standard solutions, they should be made to rigid guidelines, so the reaction you get is constant and predictable. They are often used to make comparison tests to help determine the level of concentration in a solution. That can be important when there are other metals, often not of value, that are effecting the color of a solution and you don't know what it may be. Palladium, far more so than either gold or platinum, reacts differently with different levels of concentration-----right down to different colors being displayed. I've had it confused with gold, but with brown and even green highlights in the test. It's really screwy, at least that was my experience over the years. With that in mind, I'd advise that you make a standard solution from pure palladium, to a formula that you repeat when you have to make new solution. If you know for sure the wire you've been processing is pure----what better place to find some? You don't need much-----can't recall what Hoke had to say about it, but I did everything as she directed. It sets a standard for you so your tests are meaningful. 



> I still need to save some gold as a standard to test my stannous before using, I have been making it up when needed.



I trust you do the same thing with your gold solution. If you know the precise reaction you should expect, it, too, can help you determine if a solution is concentrated, although not nearly as well as with palladium. For sure, it's a great way to know when your stannous chloride is dying. I used to mix mine @ 2 ounces, plus I'd add some pure tin as Hoke suggested. About the time it was hitting the bottom of the dropping bottle, it would fall off. Likely because it was oxidizing quite rapidly because of the low volume. When I'd test some gold, it wouldn't show much, so I'd know it was past its useful life.



> The palladium/plus rings are unknown alloy, but I am thinking they are 90% or 95% palladium with ruthenium or maybe silver. These I plan on trying AR with. I will try one first before I do any others
> as a test.



That's exactly what I'd do, too. I remember processing one of the new alloy class rings, but I was on my way out of refining before they started getting available to any degree, so I have no experience with them aside from that one, and I don't remember much about it. I'd like to hear what comes from the first one if you have time to post a report. 

Harold


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