# Pt/Pd separation



## asenic (Jul 4, 2008)

I have some impure Pt powder which contains ~2000 ppm Pd. Does anyone have idea to help me refine Pt to 3N5 ? (basically, i want to use HCl/NaClO3 as leaching process & whole process is based on inorganic system) 

Thanks for a lot!


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## lazersteve (Jul 4, 2008)

If the mix not an alloy just treat the powder with nitirc acid.

Better yet heat the powder to red heat and then treat it with HCl. The oxidized Pd will go into the solution and the Pt powder will stay behind.

Steve


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## Platdigger (Jul 4, 2008)

What is 3N5?


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## Anonymous (Jul 4, 2008)

99.95 or .9995 either way same number.


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## Platdigger (Jul 4, 2008)

Aww, Thanks! I learned smthing today....
Randy


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## markqf1 (Jul 5, 2008)

Me too, I guess...?

What do the symbols mean?
3 nines 5?
Mark


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## Anonymous (Jul 6, 2008)

99.95 percent pure


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## Lou (Jul 6, 2008)

Yes, it is a common designation used when dealing in metals or semiconductor materials. For instance, let's say I needed some silicon that was 7N5, that means 99,999995% pure. Commercial quality gold is 99,9% or 3N, or 999/1000 is gold.


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## goldsilverpro (Jul 6, 2008)

Actually, 999 Fine gold is not considered commercial pure gold. Pure commercial gold must usually be at least 999.5 Fine. Anything less would have to be refined.


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## Harold_V (Jul 6, 2008)

I, too, am under the impression that the industry standard for gold is 9995.

Harold


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## Noxx (Jul 6, 2008)

Me either.


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## Lou (Jul 6, 2008)

You're probably right if we talk of trade bars, but I would be hesitant to call it industry standard. I've seen coins that are 99,9% pure (i.e. the _commercially_ traded Chinese Panda, considered bullion) and old ingots that were "999 Fine". As far as I'm concerned, 999 is commercial quality as much as would be 917 fine in a Krugerrand or 995 in an old London Good Delivery Bar. I do suppose 9995 is the industry standard for refined gold, but what I said was still wrong: commercial gold needn't be 999.

Semantics.


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## goldsilverpro (Jul 7, 2008)

The industry standard for gold purity is absolutely 999.5 Fine. I would be willing to bet that every product Lou mentioned started with at least 999.5 gold, which was then alloyed down to make the product. Otherwise, there is no control on the amount and types of impurities present. Also, 999.5 gold is necessary to get top dollar. Anything less must be refined by someone.


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## Anonymous (Jul 7, 2008)

not to be nit picky, but is 1/2 of 1/100 percent really that important?


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## goldsilverpro (Jul 7, 2008)

It is commercially. In appearance, the difference is huge. There is twice as many impurities in 999 (1 part per 1000) than in 999.5 (1 part per 2000), if my math is right. For 999.9, it is 1 pt per 10,000 impurities.


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## Anonymous (Jul 7, 2008)

I could see your point, if I had 1000lbs of gold and 2 lbs was copper man that would hack me off, wait, I think I would be pretty happy with 998 lbs :lol:


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## asenic (Jul 10, 2008)

lazersteve said:


> If the mix not an alloy just treat the powder with nitirc acid.
> 
> Better yet heat the powder to red heat and then treat it with HCl. The oxidized Pd will go into the solution and the Pt powder will stay behind.
> 
> Steve


Thanks for your suggestion!

I will try to use the nitric acid to dissolve Pd.

If I have dissolved the impure Pt by HCl/Cl2, is there any method to remove the Pd form the solution?


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## lazersteve (Jul 10, 2008)

After expeling all the residual chlorine with heat, you can add ammonium chloride tot he concnetrated hot solution to precipitate the Pt salt. When the Pt salt is filtered out slowly add sodium chlorate crystals to the filtered solution until the Pd salt precipitates. 

The solution needs to be concnetrated and hot (not boiling) for this to work best.

Steve


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## asenic (Jul 11, 2008)

lazersteve said:


> After expeling all the residual chlorine with heat, you can add ammonium chloride tot he concnetrated hot solution to precipitate the Pt salt. When the Pt salt is filtered out slowly add sodium chlorate crystals to the filtered solution until the Pd salt precipitates.
> 
> The solution needs to be concnetrated and hot (not boiling) for this to work best.
> 
> Steve



Thanks a lot!

After the leaching step, i heat the solution as the dechlorination process.
Then I add the ammnium chloride to precipitate the Pt salt(at room temp.)
I filter the precipitate and rinse by 2M NH4Cl solution repeatly..
I ask my friend to help me assay the Pt salt precipitate ...
There is still some Pd(~150 ppm) in the Pt salt!!!
Pd in Pt(metal state) will be equal to >300 ppm, if all salt is reduced.

I have some problems

1. how to judge the end point of dechlorination?
2. Pd salt also co-precipitate with (NH4)2[PtCl6] because of incomplete dechlorination process? 
3. the dechlorination process is time-consuming process, colud i use the H2O2 to reduce the process time?

by the way ....

I got a very old reference(1935) that provides some procedures for separation of PGMs
The author separate Pt by joint precipitation of Pd, Rh and Ir as hydrated dioxides.

do u have experince in this....


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