palladium, ingots versus reagents

stratosphere · Sun Jun 05, 2005 9:56 am

ive noticed the price of commercially available palladium salts, foil, and black is way way above the price of palladium on the metals market, metal being only roughly $200/oz, whereas typical palladium reagents go for $1000/oz to much much higher. Twisted Evil

how difficult is it to turn palladium coins, ingots etc into compounds useful for chemistry?
i imagine even boiling in concetrated nitric acid it would take an eternity to dissolve something with the low surface area to volume ratio of a typical palladium coin.
i imagine one could try bashing it into a semi-foil, or maybe better yet file-ing it and collecting the file-ings., and then dissolving with nitric acid.

any bees ever done anything like this?

slacker · Mon Jun 06, 2005 8:03 am

never actually attempted it but i suppose it could be done. i must admit im not a chemist by trade but maybe one could use aqua regia. it is used to make other metal salts so it might be worth a try. i also dont know exactly how they polish the coins and bars available to the public so there might be other contaminants/compounds blended in to make them more "polish-able" that might need to be dealt with. if somebody attempts it please report back to us with the results. it would be interesting to see how this one turns out.

stratosphere · Mon Jun 06, 2005 10:39 am

slacker · Mon Jun 06, 2005 10:51 am

and just like you recommended it is probably advisable to use the filings instead of a whole coin. i believe the rhodium archive has procedures on platinum/palladium catalysts as well. if i recall correctly however, the PdCl2 file is somewhat vague citing foreign patents which i cant translate since i dont speak german or russian. i have a one troy ounce bar assayed at over 99% so i might just consider trying this one myself. im kinda leary though since i would feel like a complete ass if i ground it up into dust only to fail miserably.

bio · Working Bee

I turned an ounce ingot 99.99 suisse into the chloride, dissolving in aqua regia etc. Pounded it out to maybe 3x surface area and cut into a few small pieces with a chisel. Was afraid to lose too much dust putting a file or saw on it.

Forget exactly now but after boiling for quite a few hours it was dissolved. Put a loose cover on the beaker and don't fill more than say 1/4 because it spatters and bumps real bad so use even heat with a ring and just enough heat to barely get it boiling. At the time I had to stir by hand once in a while (very carefully)

After concentrating a few times with 37% HCl and recrystallizing it took about a day and a half of intermittent work. It's really easy, just a little tedious.

If doing it again though I would electrolyze it in HCl but at the time I didn't have a reliable procedure.

slacker · Mon Jun 06, 2005 7:52 pm

thanks for the info bio. i didnt think it would be too difficult but i wanted to see if somebody else tried it before i passed the point of no return. as an impatient young dumbass im probably going to file it anyway. any thoughts on gassing with cl as well? do you think it might speed up the process a bit?

stratosphere · Tue Jun 07, 2005 3:33 pm

i don't think a course file would create alot of uncontrollable dust, but i would have to try to find out for sure. i gather palladium is rather soft?

a few hours is an acceptable amount of time though, so the hammer procedure is workable.

how did you seperate the PdCl2 from the remaning excess nitric and hydrochloric acid? off hand i don't know what the solubility constant is for PdCl2 or how much it changes with temp. i guess you could just heat until the HCl fumes off and the HNO3 decomposes to a gas (in fume hood of course or else everything in your house corrodes even with good ventalation)

wouldn't an attempt to electrolyze palladium just result in creating chlorine gas? i know platinum electrodes don't give off Pt++ ions under a similiar circumstance.

and slacker, probobly the best thing is to do a trial run with a small amount and if it gets f-ed up at least your not out to much.

ApprenticeCook · DILLIGAF

This method is well reported on rhodium -->
https://www.synthetikal.com/Rhodiums_pdfs/chemistry/palladium.chloride.txt

Here is one of the examples:
Pure Pd (0.2 g.) is dissolved with gentle heating in about 10 ml. of aqua regia. The solution Is evaporated to dryness in a 50-ml. porcelain dish placed on a steam bath. The residue is dissolved in 10 ml. of 20% hydrochloric acid and the solution is again evaporated to dryness; this last procedure is repeated three times.

-AC

2spun · The Resistor

Humm,

kind of sounds like preparation os Alum from aluminum.
swiy has been wonder'n about this , will it also work with other metals?
Much thanks

bio · Working Bee

i..................... guess you could just heat until the HCl fumes off and the HNO3 decomposes to a gas (in fume hood of course or else everything in your house corrodes even with good ventalation) ....................................

Yep, that's exactly how it's done. Even a fume hood better be a damn good one if doing more than a couple grams. I did it on the 2nd floor courtyard outside with a big fan and when it was all over I was unscathed but the wall 3 feet away had all the paint eaten off.

I forget the details now it was so long ago but this procedure is done with noble metals in general (aqua regia treatment). Other metals especially reactive ones like Al don't require any type of drastic conditions to dissolve them . Some good inorganic prep books available on SM.

I could dig it out the electrolysis procedure if anyone is interested . Essentially it is quite sensitive to HCl concentration , current density and Faradays passed to return the target PdCl2 in near quant yield. Pricey stuff to experiment around with willy nilly.