# Help with Platinum



## jeweler1 (Oct 23, 2012)

I have successfully refined Palladium using ammonium chloride and Swimming pool tablets for the chlorine .Now I am going to attempt Platinum. The metal has Gold, Platinum and other assorted metals (I think stainless steel). I dissolved it with HCL and sodium nitrate (it took 2 days) than I precipitated the gold with SMB and tested with Stannous which showed me that the gold was gone but it was bright orange (Platinum) was still present. The solution has now been decanted (reduced to a crystalline sludge) to remove the nitrate.
I have watched the Platinum, Palladium Video many times and use it as my bible (it works and a hearty thanks).
I have 3 questions do I need to worry about the pH? And add soda ash? Because I plan to precipate with ammonium chloride as the video explains do I need to use Zinc powder for anything? Now should I use hcl or water to rehydrate the solution?
This forum has been a great help, keep up the good work and a hearty Thank you


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## samuel-a (Oct 23, 2012)

jeweler1

Not knowing exactly how much base metals you have and how much platinum you have there it is a bit hard to tell what would be the best next step.
What was your source material ?


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## jeweler1 (Oct 24, 2012)

The base material is stainless steel with gold and platinum inserts I retrieved 8.1 grams of gold. The stainless steel didn’t dissolve and I really don’t know exactly how much platinum is left. I dissolved it in a 2000 liter beaker and it took 2 try’s to get all the plat out (I tested the third time and no more plat). The first and second time the stannous was bright orange. 
I would guess that there is about 4 to 5 grams of platinum dissolved in the 3700 liters of solution .I reduced it to 600 liters with a lot of crystals and a dark orange color almost red.


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## samuel-a (Oct 24, 2012)

I would assume you meant ml instead of liters.

Though uncommon, some SS doesn't dissolve well in AR. And as you say, the SS didn't dissolve so i would assume all you have is Pt in solution with very little iron and other metals.

Best thing in my mind is to simply start over.
Rehydrate the crystals that formed earlier with dilute HCl and combine all the solutions. Then *cement everything with Zinc or Aluminum.
Wash resulting black powder several times with boiling hot water and start over treating it as Pt black (AR ->de-NOx->NH4Cl).



* If the amount of powder formed while cementing is unproportionally larger then the amount you are expecting (4-5g Pt), then you have cemented other metals along with the Pt and you would need to dry the powder, incinirate it and pre leach it with warm dilute (1:3-5) nitric acid first to eliminate as much base metals before dissolving the Pt.
You might want to cement a small sample first to see how thing going.


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## nickvc (Oct 25, 2012)

When dealing with stainless I find it easier to remove that first, hot hydrochloric will normally dissolve the stainless leaving the values untouched. If these were rings then I'd suggest you use a ring stretcher if you get any more, simply feed them onto the spindle and stretch them aggressively, they tend to split allowing the inlays to be removed by hand.


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## jeweler1 (Oct 25, 2012)

I need to do some explaining. This is in the form of small pieces about 6 mm x 3mm x 2mm thick there are around 20. The gold is an insert’s soldered in the stainless and the platinum is a small wire also soldered in there are rubies also held by the wire. This isn’t a homogeneous mass it has lots of tiny pieces. When the gold dissolved I could still see some wire left so I redissolved it until the wire was all gone and the rubies fell out (I did it again just to be sure) the last time there was no plat or gold in solution. The stainless (if that is what is) didn’t dissolve even after 3 tries. I just set it aside and worked with the solution and removed the gold (8.1 grams) the only thing in solution now is Platinum. 
Should I dilute it up with HCL or water?


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## Geo (Oct 26, 2012)

rhodium does not dissolve well in AR, even when heated. is the metal white and shiny?


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## samuel-a (Oct 26, 2012)

Geo said:


> rhodium does not dissolve well in AR, even when heated. is the metal white and shiny?




Sounds more like Ti to me...


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## jeweler1 (Oct 27, 2012)

Oops I do mean milliliter not liter and yes the metal is shinny but I’m almost certain it’s not rhodium. When I dissolved Palladium I reduced it by simmering it to a crystalline sludge than I added pure HCL to redissolve it. It worked fine but I think I could have used Water instead? That is why I’m confused about what to redissolve it with? 
What is Ti?


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## jeweler1 (Oct 27, 2012)

Ti is that Titanium? If so no it’s too heavy for that I’ve worked with that metal before


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## freechemist (Nov 5, 2012)

jeweler1:

_"...the only thing in solution now is Platinum. Should I dilute it up with HCL or water?"_

If you intend, to precipitate the platinum as hexachloroplatinate, you shouldn't dilute the solution any more. Potassium- and/or ammonium hexachloroplatinate are best precipitated from concentrated solution. A good concentration-range would be around 50 grams Pt in a liter of solution.
If you want to cement with zinc, it is important, that your reaction mixture is always acidic. After complete reduction, decant/filter, wash the solids with copious amounts of water and take them up again in a reasonable volume of ca. 1-2M HCl. Let the mixture boil for ca. 15 minutes, filter and wash again with water, then dry and finally calcine at 600oC-800oC.

Ti, indeed, means titanium, which occasionally is used in jewelery, together with platinum. Although being not a precious metal, it is highly corrosion-resistant, such, that it can well be used as a construction-material for reaction-vessels in wet-chemical precious-metal recovering and -refining.


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## jeweler1 (Nov 9, 2012)

"If you intend, to precipitate the platinum as hexachloroplatinate, you shouldn't dilute the solution any more"
Thank you for that information But the solution now has a lot of crystalline solids in it How do I deal with that?
From what I understood I should dilute it to it's original level but you say not to do this ? And can I use water?
sorry it took so long to respond I work allot and don't have much time (eating and sleeping)
This solution has a lot of Platinum and I want to get it out correctly.
I'll send pictures if I have time


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## butcher (Nov 9, 2012)

I would add a solution of ammonium chloride and some heat.


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## jeweler1 (Nov 9, 2012)

Here are some pictures which might help I do plan on using Amonium chloride to precipate . Thanks


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## jeweler1 (Nov 9, 2012)

This is a picture of the solution evaporated so far


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## butcher (Nov 10, 2012)

I have not followed this thread, and honestly have not read what has been done up to this point.

The solution is already concentrated to the point of salts forming.

I would separate that red-orange liquid from the salts formed.

Just wetting the salts with ammonium chloride with heat, much of the salt would go into solution and precipitate the platinum from the salts, after decanting this ammonium chloride salt solution, from any of the platinum, I would add that platinum powder back to the red-orange solution, and go on from there.

This should leave your main solution concentrated.

The decanted ammonium chloride salt solution used to dissolve the salts check this for values, if not enough value to precipitate from this solution use the stockpot or zinc it out.


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## freechemist (Nov 23, 2012)

@jeweler1:

Judging the colour of crystals and solution on your pictures, the mixture contains a lot of sodium salts, and also some platinum, like shown by the SnCl2-test. To work with such concentrated solutions is difficult, especially if they are of sirupy consistence and in precipitation/filtration-operations. Therefor I gave you a reasonable high concentration-range for platinum to work with, 50 g Pt per liter of solution. Sorry, I didn't specify, that I meant a high concentration in platinum, not in "valueless" alkali-salt. Speaking of a highly concentrated platinum solution usually means a solution with a high concentration of platinum, like speaking of concentrated hydrochloric-, sulfuric- etc.- acid.

The best way to work up your crystal/solution-mixture in my opinion is to treat it with ca. 1 M HCl (e.g. 100 ml conc. HCl + 900 ml water => 1 liter ca. 1 M HCl), under constant stirring until all crystalline material is dissolved and finally cementing with small additions of zinc-powder by known procedures, always giving attention, that the mixture remains strongly acidic. Thus you obtain finally, after appropriate purification and calcination, raw platinum as an usually grey powder, which can be weighed (much important), and which gives you a reliable base to calculate upon the amounts of reagents to be used in dissolving it, and to precipitate it as a hexachloroplatinate(IV) in the following recovery/refining-steps.


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## jeweler1 (Dec 30, 2012)

I’ finally getting back to this project and thanks to all your help. I pored off the concentrated solution than diluted the crystals with HCL and added concentrated Ammonium Chloride solution. The mix than turned a beautiful orange color and left reddish sediment. The solution now tests negative for all values. I just ordered a vacuum filtration system and a fused quartz dish. So the next step will be to filter/wash with Ammonium Chloride solution, dry and heat in my dish. I’ll post the results. Thanks again for all the help.


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## samuel-a (Dec 31, 2012)

jeweler1

Nice work.

Maybe it is just the picture settings, but the color of your platinum ammonium chloride seems to be wrong, as if some Pd was also precipitated with it.
Though, once you calcine and wash it with water, you can easily remove Pd by boiling it in dilute nitric acid.


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## butcher (Jan 3, 2013)

Iron in solution will give several colors yellow, green, red brown rusty.

Iron will also easily form a red rouge iron hydroxide, which is very hard to put back into solution, after it forms, even aqua regia or the acids and oxidizers we use to dissolve gold have a hard time oxidizing the red rouge iron powders back into solutions, thus the gold powders will normally dissolve back into a solution leaving most of the Iron hydroxide red rouge untouched.

I do not know that iron is in solution or the powders, but I kind of suspect the pinkish color of the powders may be from iron, Hokes book describes a test for iron in solution on page 100.

HCl will attack stainless steel, (high oxidizers seem to passivate chromium to slow the attack some what) when dissolving it is slow, but it will dissolve, thus putting Iron into solution, as well as some of the other metals involved in stainless steel such as nickel, or chromium as well as other metals in its composition.

Platinum is also very resistive to the acids; even a solution of hot aqua regia can have a difficult time putting platinum into solution. 

I cannot say that the color of the powders is from iron hydroxides (red rouge) included, but I would suspect it being mixed in with the precipitant.


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## lazersteve (Jan 3, 2013)

Collect a small sample of the salmon colored powder with a vacuum filter. 

Dissolve a sample of the filtered colored powder with warm HCl and divide the sample into two roughly equal volumes.

Test the first sample with DMG for Palladium. If a fluffy yellow precipitate forms, filter this off and test the left filtered solution with stannous chloride for Platinum.

Test the second sample with stannous chloride for Rhodium.

Photos of the resulting colors for the above tests can be found in the Guided Tour--> Reaction List 

Judging from the salmon pink color of the salt, I'm guessing the salt contains some (perhaps mostly) Palladium. I believe you have made Vauquelin salt, the Palladium analog of the olive drab green Magnus' Salt composed of Platinum and the ammonium ion. If it is not Vauquelin’s salt, it may be as Butcher stated, a contaminated platinum ammonium chloride.

Steve


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