Non-Chemical Iodine/Iodide & Rhodium

[Comanche]

Does anyone know how efficient the Iodine/Iodide leach is for dissolving Rhodium either out of ores or out of electronics?
If it works, I wonder what would be the best precipitant for the Rhodium?
Thanks!

 

[goldsilverpro]

The first thing you would have to do is find some very, very rare type of electronics (or, ore) that contains rhodium. In 40 years, the only electronics I have seen that were guaranteed to contain rhodium were some fingers plated in the early '70's. I have heard lots of stories about rhodium being on some of the more modern electronics, but I've never seen or heard of any results. With the price, rarity, and working difficulty of rhodium, it would only be used in a particular application where nothing else would work, such as gold, platinum, palladium, nickel, etc.

I would doubt very much that I2/KI solution would dissolve Rh. I would doubt that you could find any common chemical(s) that would dissolve rhodium, unless it were very, very finely divided. Commonly, rhodium is dissolved in certain fused salts (molten chemicals) or, I believe, high temp chlorination, usually performed in a tube furnace.

 

[Comanche]

Well, I suspect that I may have some ore and also some concentrates that may have natural rhodic gold in them.
At this time, it is my belief that a lot of rhodium in ores is missed due to the insolubility problem with most leaches, as well as probable other causes. Once the gold in the rhodic gold has started dissolving, then the rhodium becomes the outer surface and stops any further dissolution by leaches.
So, my intention was to find out if anyone knew if the iodine leach would dissolve the rhodium along with the gold in such an ore or piece of jewelry made of a gold-rodium alloy.
I apologize for not being more succinct and direct in presenting my query to begin with.
Now if I can locate some gold-rhodic alloy jewelry to experiment with, that would be the real ticket! Also some known rhodium would also be great to also test with.

 

[Harold_V]

Now if I can locate some gold-rhodic alloy jewelry to experiment with, that would be the real ticket! Also some known rhodium would also be great to also test with.

In all my years of refining (for jewelry manufacturers), numbering just over 20, I never encountered any alloy of gold/rhodium. The closest I came was rhodium plated items, often white gold, or even sterling, to prevent tarnish.

What advantage would there be in alloying with rhodium for jewelry that couldn't be addressed just as well, for 1/10, or on today's market, much less, the cost of palladium? I'm not convinced there is such a thing. Could you enlighten me if you are aware of such an alloy? White gold is typically alloyed with nickel, and on rare occasions, palladium.

Harold

 

[Comanche]

Harold, I cannot dispute you. I am not a jewelry man by any means. It just made sense to me that very wealthy individuals would enjoy having very, very expensive pieces of jewelry made of a rhodic/gold alloys, as they do of other platinum metals.

In any case, it appears that the only way that I am going to get to the bottom of this is to just go ahead and begin doing some tests on known rhodium samples, including some Rhodite, the mineral of rhodium and gold that is worth a fortune when located!

This field has hardly been touched yet by mainstream sources. I do suspect that there are certain very clever individuals or groups that operate in secrecy (with very good reason) that have all the answers I am seeking. This would also explain why the sparse information on this mineral and subject!

A quick and interesting read on the platinum group of metals and their association with gold and silver that piqued my interest to investigate it further is located at:

http://www.minsocam.org/ammin/AM22/AM22_1016.pdf

With Rhodium at $6,000+ oz. and gold rising, I must pursue this avenue at this time in conjunction with my other works! :lol:

 

[Irons]

Well, I suspect that I may have some ore and also some concentrates that may have natural rhodic gold in them.
At this time, it is my belief that a lot of rhodium in ores is missed due to the insolubility problem with most leaches, as well as probable other causes. Once the gold in the rhodic gold has started dissolving, then the rhodium becomes the outer surface and stops any further dissolution by leaches.
So, my intention was to find out if anyone knew if the iodine leach would dissolve the rhodium along with the gold in such an ore or piece of jewelry made of a gold-rodium alloy.
I apologize for not being more succinct and direct in presenting my query to begin with.
Now if I can locate some gold-rhodic alloy jewelry to experiment with, that would be the real ticket! Also some known rhodium would also be great to also test with.

I have seen native Gold/Rhodium alloys. They're not very common.

I've also seen a mixture of Platinum and Rhodium digest and at the end of the day, the Platinum is in solution and the Rhodium looks just as bright and shiny as when it was put into the digester.

The easiest solution to a Gold/Rhodium alloy that passivates is to inquart it with sufficient Gold so that it can be digested, leaving the Rhodium as a precipitate.

Refiners take a steep discount on Rhodium because of the labor and materials it takes to refine it.

My suggestion is to save up any Gold that doesn't dissolve until you have enough to inquart it or get a quote from a refiner once you have enough to make it worthwhile.

At the end of the day, you're going to have to sell it to a refiner anyway, and they are going to get their pound of flesh, regardless.

This is why Rhodium is so expensive. It's like trying to get blood out of a turnip, as the old saying goes.

 

[Irons]

Does anyone know how efficient the Iodine/Iodide leach is for dissolving Rhodium either out of ores or out of electronics?
If it works, I wonder what would be the best precipitant for the Rhodium?
Thanks!

To answer your question:

Check patents on line. There is one using Iodine, Iodate and Oxygen under high pressure.

Looks like an expensive process.

 

[Comanche]

One last thing on this topic. Powdered Rhodium will dissolve quickly in hot concentrated Sulfuric Acid H2SO4, and solid rhodium will also dissolve but takes a lot longer. But it is gradually dissolved over time in pure H2SO4 at just under boiling.

 

[mike.fortin]

Comanche--if sulferic digests honeycom then is rodium in same soluton? How do we take them two apart to make money on rodium? Mike.

 

[lazersteve]

Mike,

Check this post:

Rhodium Metal

Steve

 

[Comanche]

Steve, which post specifically are you referring to? And which part of the post?

Mike, what do you mean about dissolving honeycom (honeycomb?) in sulfuric acid, then is rhodium in the same solution? I don't follow what you are asking here at all! :lol:

 

[lazersteve]

Comanche,

The link I posted should take you directly to a post concerning Rhodium. It's in the PGM section under "Rhodium Test".

Steve

 

[Comanche]

Steve,
I must presume that you are referring to fusion with sodium bisulphate ( I use the spelling bisulfate). I was not aware that rhodium minerals would dissolve in a fusion of sodium bisulfate.....I am glad to learn that!

My method is to fuse the mineral or powdered unknown metal with POTASSIUM BISULFATE completely. Dissolve in DW, filter and then treat the clear solution with ETHYL ALCOHOL which drops only the pure rhodium metal as a very fine black powder. It works great for me!

Potassium Bisufate is a much, much stronger oxidizer than sodium bisulfate.

 

[lazersteve]

Comanche,

I posted a reference to the potassium bisulphate method earlier in the same thread, but did not include the process to precipitate the rhodium.

Steve

 

[Irons]

Steve,
I must presume that you are referring to fusion with sodium bisulphate ( I use the spelling bisulfate). I was not aware that rhodium minerals would dissolve in a fusion of sodium bisulfate.....I am glad to learn that!

My method is to fuse the mineral or powdered unknown metal with POTASSIUM BISULFATE completely. Dissolve in DW, filter and then treat the clear solution with ETHYL ALCOHOL which drops only the pure rhodium metal as a very fine black powder. It works great for me!

Potassium Bisufate is a much, much stronger oxidizer than sodium bisulfate.

If you have time on your hands, the Rhodium usually drops out on its own on standing. It's one of the problems of making stable Rhodium solutions, any impurities will cause the Rhodium to drop out.

 

[Comanche]

Yes Irons,
However, I use the ethyl alcohol (Everclear) method because then I am sure that all the rhodium has been reduced out of the fusion solution, and of course, like you said, there is no waiting around to filter and wash it off!

 

[Comanche]

One of the reasons that I brought this topic up, was because I recently did an Iodine/Iodide uptake on some ore that I got in New Mexico this summer on a prospecting expedition.

The area is a know gold area and pgms have long been suspected to be inherent in some of the ores there also.

Anyhow, I did a zinc drop on the solution. After rinsing the precips with strong HCL Acid to remove the zinc residuals, I had good gold and quite a lot of another metal. Under microscopic examination the gold was metallic gold crystals of course, and the main other metal was a very silverish white metal with a very strong rose tint, which led me to believe that good rhodium was present also.

However, I did not know if this leachant of Iodine/Iodine would dissolve Rh or any of the platinum group elements out of an ore. Apparently a 7% solution will dissolve some of the pgms along with the gold and silver also.

So, I am left with the option now of doing a larger batch, and getting enough precipitates to send off for spectrographic analysis before I make any further judgements or come to any real conclusions on this final precipitation product.

Another test that I plan on doing to these precipitates is to fuse them with about 4 to 5 parts of pure silver powder inquarted, then take that alloy and do the nitric acid bath to remove the silver and any palladium present and see what is left then besides the gold.

Slowly but inexorably, I shall find the truth! :lol:

 

[Irons]

As Harold mentioned elsewhere, PGM loss can occur when Silver is Alloyed with PGMs and Nitric Acid is used.
Gold is the recommended iquarting material for Rhodium.

I know it's a pain but Gold has been proven to give the best recovery.

Since you have the recovered material in a fine powder to begin with, why not just dissolve the Gold away, leaving the Rhodium?

Rhodium is usually the last metal to be recovered because, after everything else is dissolved, it remains as a residue.

I wish you the best.

Another thing you might look at is using Nickel Sulphide as a flux to extract any PGMs, it's what many commercial refineries use to leach PGMs from the Gold melt. It works best when the Gold contains a small percentage of PGMs and saves having to dissolve the Gold to extract them.

 

[Comanche]

Thanks for the ideas Irons.

When dealing with pgms, I always digest the silver, copper, etc. with sulfuric not nitric. Works for me.

 

[Comanche]

I should have said that some of if not all of the rhodium also dissolves (most of it) in the sulfuric, but you have your gold and platinum etc. left.

Actually, the best thing of course is if you know exactly how much pgms you have with your gold, then you can send it directly to a refiner you trust, even though you may take a small hit on the price, it will save you that much and more on time, chemicals, and etc.