# Platinum Precipitation



## kroutonz (Feb 26, 2011)

I boiled the pgm's in aqua regia then filtered, then evaporated two times to not totally syrup, but close. dark red color. 

I added HCL after each evaporation, but when I tried to precipitate pt nothing happened. Is it possible theres still nitrates in the solution? i didn't see much brown fumes when evaporating/boiling AR, but its only 10ml or so nitric.

Does the pt solution / ammonium chloride need to be hot to precipitate?

I left after like 30 minutes, is it possible I'll go back and see a precipitant?


----------



## lazersteve (Feb 26, 2011)

What does a sample of the solution test like to DMG followed by a stannous chloride test? 

What was the source of the PGMs?

Steve


----------



## kroutonz (Feb 26, 2011)

4-5lbs of catalytic converter material. Tests positive still for both pt, pd. I think its mostly pt.


----------



## kroutonz (Feb 26, 2011)

And thats with stannous. I don't have DMG.


----------



## lazersteve (Feb 27, 2011)

Without DMG it's very difficult to discern Pt in the presence of Pd with stannous chloride. The proper test procedure is to remove the Pd with DMG, then test the resulting filtered solution with stannous for Pt.

At this point you can still zinc out the mixed PGMs and remove the Pd with nitric acid after cleaning off the zinc with 20% sodium hydroxide as Lou has posted.

After you strip the mixed powder with nitric you'll know if you have more than just Pd if there is a residue and fresh nitric no longer reacts with it.

Steve


----------



## kroutonz (Feb 27, 2011)

Can I just sodium chlorate pd out? I know there is definitley both I just assumed it was more platinum since the color was red, and the stannous was bright red/orange at first then turning black/yellowish.


----------



## Lou (Feb 27, 2011)

The separation of ammonium hexachloropalladate and ammonium hexachloroplatinate is not an easy one. Many seem to think that one can have a 50/50 HCl solution of Pd and Pt and separate them with 100% efficiency. Any residual chlorine present (or nitric acid) guarantees palladium contamination in the platinum salt regardless of how you wash it.


----------



## patnor1011 (Feb 27, 2011)

I can help if you need DMG just for testing. 
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=58&t=9158


----------



## kroutonz (Feb 27, 2011)

OK well I tried to evaporate the solution again(to syrup this time) This time I got blackish residue at the bottom which didn't really look like the crystals in the dvd, but I re staturated with hcl and most of it re dissolved. What didn't I filtered, and kept the filter.
I then tried to drop any pt again. I assumed there was nitrates last time but they must be gone now. Again nothing, or very little. so I moved on to the pd. I dropped a couple miniscule amounts of sodium chlorate expecting a bubbling but it didn't happen. I did get a precipitate from the sodium chlorate though, which I filtered and was a redish/brown powder thats drying now. The solution was still a redish color so I stannous tested and still got results for what i think is pt and pd. It turned bright orange then alot lighter of a black/yellowish color for the pd vs last times dark black color.

I'll try and get the remaining pd out of the solution, but based on others stannous tests, and the color still in the solution I'm pretty sure theres pt. Does the pt solution need to be heated to drop, or ammonium chloride need to be heated to drop any, or can it be done at room temperature, the heat is just to dissolve more ammonium chloride?

What would be the ramifications of just throwing the solution back into my bucket thats processing cats assuming theres still some ammonium chloride in it?
Would the ammonium chloride from last time be evaporated with the nitric when I'm denoxxing? 

I'm going to calcine this powder and try and melt it later tonight/tomorrow, but any help is appreciated greatly.


----------



## kroutonz (Feb 27, 2011)

For the filters I never found out how you guys get the powder off without any filter paper/ not leaving 50%+ powder on the papers? my ammonium palladium has a very thin later of paper.. Can I just burn this off in the calcining process?


----------



## kroutonz (Feb 27, 2011)

Well you guys helped me in another thread, with the sulfuric acid method, but that seems dangerous, and I know 90% of the people on here don't do that. Do you guys wait til the filter is completely dry, or scrape it while its wet into a ball? My "powder" was mud colored, and textured. It didn't have much moisture in it after 2-3 hours in the sun/heat.


----------



## lazersteve (Feb 27, 2011)

I thoroughly rinse my colored PGMs salts with a diluted ammonium chloride solution (~15%). 

The dried salts barely stick to the filter paper. I rinse what does stick to the paper into a stock pot for PGMs and pitch the filter paper in the PGMs burn pile for PGM paper waste. 

What type of filter paper are you using?

Steve


----------



## kroutonz (Feb 28, 2011)

I'm pretty sure my filters arn't that great. They're lab nerd or something or other that came with a vacuum pump kit. To wash the salts should i just wash them into a jar with the dilute solution and stir/shake them well?


----------



## kroutonz (Feb 28, 2011)

to purify the powder should I just dissolve in ammonia water or ammonium hydroxide and drop it back out with hcl, then filter?


----------



## lazersteve (Feb 28, 2011)

kroutonz said:


> I'm pretty sure my filters arn't that great. They're lab nerd or something or other that came with a vacuum pump kit. To wash the salts should i just wash them into a jar with the dilute solution and stir/shake them well?



As I demonstrate on my Fundamentals of Pt and Pd DVD, you rinse the salts while they are still in the filter.

Pd is purified as detailed here:

Purifying Dirty Pd Salts

Conversion of the resulting colored powders (Pd and Pt) can be converted using the posted by Lou and detailed here:

Converting Pd and Pt Colored salts to metal powder

Steve


----------



## kroutonz (Mar 1, 2011)

Well I tried today and used 2.5% ammonia on accident. I dropped what I dissolved with zinc, and I will take the filter that I thought contained contaminents and boil that in AR. Oh well. I did learn there was probably no pt/ very very little. 
I guess I'll order some good filters while I wait to reboil/ precipitate the pd again.


----------

