Assaying Platinum

shop deals on amazon
Advertise with us
Shop deals on ebay
xelexo
Gold Refining Forum

Help Support Gold Refining Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Hi Butcher
Thanks for showing intrest in this thread
I dont have a sample like this on hand
I am a jeweler
To have a mixture like is not common but it does happen
For example you can have filling from 10k,14k ,18k jewelery that can have rhodium plating on it and in the mixture you can have pt,pd iridium .silver.
I just thought about it
Hoke has a chapter on refining a mixture that is similar.
I will try to read the details
its on page 111
she says remove base metals with nitric
she says it contains silver ,copper and base metals
I dont know why she doesnt say that some of the platinum group metals will also go in there,specially palladium
 
Mexpert,

I think you are confusing recovery techniques with assaying techniques, this thread was for assaying platinum.

That being said, the methods commercially employed for separating and purifying precious metals are for the most part, adaptations of classical wet assay procedures. Assayers usually work on samples of about 1/3 to 1/2 of a pennyweight. (.5 - .75 grams) If you were to apply the techniques to separate all of the metals you mentioned on a sample that small, you would have to be charged thousands of dollars for the assayers time. The results for the more oddball metals like Osmium or Ruthenium will likely involve weighing fractions of a milligram. That is where ICP is truly worth its weight.

Now if you are talking about size able quantities of these metals mixed and concentrated as they would be in anode slimes, then there are methods you can follow to recover all of the metals you listed. I personally have used these methods to produce sale able quantities of Platinum, Palladium, Rhodium, and Iridium. The issue you may have, or shall I say will have, is that unless you have an end market for these metals (as I did in the heyday of Jewelry in NYC) you will not be paid for your efforts to refine them.

I have used methods developed by INCO to refine concentrates that I made from smelting with collectors and refining all of the precious metals from slimes.

Aqua regia can dissolve Au, Pt, and Pd and all can be recovered and purified relatively easily. The insolubles are Rh,Os,Ru,Ir & Ag. All of these can be recovered as well. I have personally recovered all but the Ruthenium, (it requires a distillation which I felt wasn't cost effective). I once concentrated Osmium in quantity from cellular stain used in electron microscopy, it was one of those things I did because I was more chemist than businessman, never again.

If you have the need I can post the methods on the forum, they all assume you start with a feedstock of PM concentrate which you will have create to concentrate the metals. That involves using electrolytic cells to concentrate the metals as slimes in copper electrolytic cells. The methods are not for the faint of heart as it involves real chemistry so I won't post the methods unless you ask. (plus it involves a lot of typing.)
 
Hi 4metals
Thanks for your reply.
Those files seem like they are worth having.
When you have free time than maybe you can post it here.
I am not in a rush for them and also I am not a chemist so i hope that I will be able to understand it.
Thanks again
 
Hi 4metals
Thanks for that good post
Here is the link so that in the future we will be able to find it more easly

Separation and Purification Au,Pt,Pd,Ag,Rh,Os,Ir,Ru
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=51&t=6638
 
this I would not do for an assay, I would look for a good assayer to work with, you need to keep customers they can be bread and butter.

http://pubs.acs.org/doi/abs/10.1021/ja01975a002

http://chestofbooks.com/reference/Ameri ... tinum.html
Click to expand...
Hi Butcher
I did a bit of reading on what was on these sites.

The metal may be obtained in this latter form in several ways, of which the following is one of the most convenient. A solution of chloride of platinum is boiled with an excess of carbonate of soda, to which a quantity of sugar has been added, until the resulting precipitate becomes black. Chloride of sodium is formed, water and carbonic acid are produced by oxidation of the sugar, and the platinum is precipitated, so finely divided that it appears black. This powder is then collected on a filter, washed, and dried by a gentle heat, when it is found to have the power of condensing gases, especially oxygen, in its pores to a remarkable extent. It almost instantaneously converts alcohol into acetic acid, often with sufficient rise of temperature to cause combustion. It also converts wood spirit into formic acid. The unalterability of platinum at high temperatures, and its power of resisting the action of most chemical agents, render it useful for crucibles, evaporating dishes, forceps and foil for blowpipe experiments, and for other chemical and philosophical apparatus. Large platinum stills, sometimes weighing 2,000 oz., are used for the concentration of sulphuric acid.
Click to expand...

This sounds different from what ther is in the Hoke book and the method we talk about here.
Maybe I have to read it more carefully
What do you folks think
 
I think I'd like to find a platinum still!!

I know there is apparatus kicking around that is indeed solid platinum--at the various universities I've been to/attended/toured, there is always some old platinum-containing equipment.
 
Lou said:
I think I'd like to find a platinum still!!

I know there is apparatus kicking around that is indeed solid platinum--at the various universities I've been to/attended/toured, there is always some old platinum-containing equipment.
Click to expand...

$3,082,000 at today's quote. ($1541) That's a nice round number.
 
If you send to a lab they will do this: Part the material with 20% hno3 to rid of the silver and some of the Pd. Then filter the solution and save the filter and solution. They would then A/R the filter paper from the nitric solution. Once all completed they would run the 20% hno3 solution and the the a/r solution by ICP.
 
4metals said:
By using gold or platinum as a collector you will collect all of the PGM's in one bead and you can decide where to go from there. If you add a relatively large (10 x the expected Pt content) silver charge, the Pt and Pd will go into the nitric when parting in nitric. There are methods to part in different acids to separate the Pt from the Pd.

If you add gold as a collector you are doing it to facilitate the Pt dissolving in the aqua regia so you can boil off the nitric and drop ammonium chloroplatinate in a classic method.

If you have all of the metals you listed, Rh, Ir, Pt, Pd and Au Lou is right ICP is the way to go, gravimetric assays for multiple PGM's are the most difficult assays to perform, and when you're buying, you can lose more than you gain if you screw up.

Some of the guys who post here have XRF machines, I don't recall who has what (maybe if those that have an AA or ICP or XRF said so in their profile we could be more helpful) Anyway if you have an XRF you could produce a assay bead by cupellation with the added benefit of a gold or silver collector, and run an XRF assay and do the math to calculate what was in the original sample.
Click to expand...
4metals I really wouldnt trust an xrf reading on low % mixed metals,I had a sample of gold plated brass chain that showed Pd and Pt that wasnt there,they are fine if you want to check that its 95% or 99% Pt or 18 carat or 14 carat Au but useless in determining accurate % in mixed metals,lets say I wouldnt buy based on the results,might sell :roll:
 
Nick

If you make your own standards for XRF and run samples matching the parameters the sample was set up for, the XRF can be very accurate. That is what I meant in the last part of what you quoted from a post I had made. By making samples with gold or silver as a collector in the same general proportions as standards made the same way, you will get a good idea.
 

Latest posts

Back
Top