Separation and Purification Au,Pt,Pd,Ag,Rh,Os,Ir,Ru

[hitesh hakani]

Is there any alternate chemical for sodium paroxide to get iridium dioxide

 

[Rougemillenial]

These methods are to process concentrates and are usually not worth processing small quantities. The details have been left out for the Ruthenium and Osmium as these are really dangerous metals and should only be handled in closed reactors.

Separation and Purification Au,Pt,Pd,Ag,Rh,Os,Ir,Ru

This is a general schematic for processing a concentrate of any combination of the above listed metals usually generated from anode slimes or slimes collected from cementation of waste acids holding values.

Roast the slimes to convert any PdO to metal to assure its place in the soluble fraction.

The concentrate is treated in aqua regia, this solubilizes the gold, platinum and palladium and leaves the other metals in insoluble form.

The solution basically contains HAuCl4, H2PtCl6, H2PdCl4. Drive off the NOx by classic boil down and successive 3X’s addition of HCl. Drop the gold with either Sulfur dioxide or Ferrous sulfate. It has been suggested that reducing the gold with Ferrous sulfate results in a more complete drop of the platinum in the following steps. Gold, with either precipitant, will have to be re-refined for high purity. Alternatively the gold can be extracted with Dibutyl carbitol and recovered with oxalic acid resulting in a high purity gold and leaving the Platinum and Palladium behind for recovery.

The Pt is dropped by treatment with Ammonium chloride to drop the insoluble (NH4)2PtCl6. These salts are washed with a solution of 15% ammonium chloride and dried. The salts are collected and further purified via bromate hydrolysis.

Pd is dropped with a solution of dimethylglyoxime dissolved in dimethyl sulfoxide. The yellow palladium glyoxime is filtered and washed with 60% alcohol and 10% HCl. The alcohol assists in the drying and the dry palladium glyoxime is dissolved in excess ammonium hydroxide until dissolved and generating a clear solution. The addition of HCl results in the precipitation of diaminopalladous chloride salt or “palladium yellow”

You have now completed the easy part, the following treatment is for the insolubles left behind in the aqua regia process.

The insolubles are smelted with lead carbonate, carbon, borax and soda ash. This forms a slag with silica, alumina and base metal impurities. The PM’s are dissolved in the lead. Separate the lead and the slag, remelt the lead and granulate it in nitric acid. Filter off the insolubles, Rh, Ru, Ir, and Os.

The silver and lead are in the Nitric acid, sulfuric acid is added to drop out the lead as insoluble lead sulfate. This is collected and converted to lead carbonate and recycled. Classically the silver is dropped as a chloride and smelted but cementation with copper yields an effective product for further electrolytic purification.

The insolubles filtered off are fused at 500 C with molten sodium bisulfate. This converts the Rhodium to water soluble Rh2(SO4)3 . The Ru, Os, and Ir are untouched. The sulfate cake is cooled and dissolved in water, the insolubles filtered off and the Rhodium is precipitated with NaOH and collected for further purification as quantities warrant.

The remaining insolubles are fused with sodium peroxide and sodium hydroxide at 500 C forming water soluble sodium hyperosmate and sodium ruthenate. The iridium is now Iridium dioxide.
The iridium dioxide is dissolved in aqua regia and precipitated as ammonium hexachloroiridiate with ammonium chloride. The salt is further purified by digestion in dilute ammonium sulfide which will precipitate impurities filtered and re-precipitated with ammonium chloride to reform the ammonium hexachloroiridiate. This can be reduced in hydrogen at 1000 C to pure metal.

ok. one DMG won't drop ammonium tetrachloropalladate efficiently. two the lead nitrate produced in the recovery after the firing with litharge is extremely dangerous. the best idea i would have is to cuple the lead. the metals remaining can be dissolved in a bit of copper and granulated as normal. also chlorine gas will drop the palladium as hexachloropalladate.

 

[upcyclist]

ok. one DMG won't drop ammonium tetrachloropalladate efficiently. two the lead nitrate produced in the recovery after the firing with litharge is extremely dangerous. the best idea i would have is to cuple the lead. the metals remaining can be dissolved in a bit of copper and granulated as normal. also chlorine gas will drop the palladium as hexachloropalladate.

On your points:
1) It's been mentioned throughout the forum, but not in this post as you point out, that DMG is not very efficient. It may be "efficient enough", however, for the small-scale refiner who's only processing slimes.
2) Can you quantify how dangerous? More dangerous than the aqua regia, nitric acid, and platinum group salts already involved in this process? I already know the process in general is a hazard, and many like me choose not to refine our own PGMs for this reason. And we all (should) know that any chemical refining process involves chemicals that require serious risk management.

Oh, and I get it if you're on your phone and have limited editing power, but it's helpful to edit down long quotes to only include the relevant sections. Sometimes, when I'm feeling lazy, I just copy and paste the whole thing as many times as I need to, then delete out different bits for each iteration.

--Eric

 

[Rougemillenial]

thanks Lou

what shall i do to dispose of the potassium chlorate about 300grams or so

and I don't want to build a rocket or smoke up the neighborhood ? :|

Add some manganese dioxide and lightly heat. The Manganese dioxide will decompose the chlorate quickly into the corresponding chloride and oxygen

 

[Rougemillenial]

ok. one DMG won't drop ammonium tetrachloropalladate efficiently. two the lead nitrate produced in the recovery after the firing with litharge is extremely dangerous. the best idea i would have is to cuple the lead. the metals remaining can be dissolved in a bit of copper and granulated as normal. also chlorine gas will drop the palladium as hexachloropalladate.

On your points:
1) It's been mentioned throughout the forum, but not in this post as you point out, that DMG is not very efficient. It may be "efficient enough", however, for the small-scale refiner who's only processing slimes.
2) Can you quantify how dangerous? More dangerous than the aqua regia, nitric acid, and platinum group salts already involved in this process? I already know the process in general is a hazard, and many like me choose not to refine our own PGMs for this reason. And we all (should) know that any chemical refining process involves chemicals that require serious risk management.

Oh, and I get it if you're on your phone and have limited editing power, but it's helpful to edit down long quotes to only include the relevant sections. Sometimes, when I'm feeling lazy, I just copy and paste the whole thing as many times as I need to, then delete out different bits for each iteration.

--Eric

Lead nitrate is slightly more dangerous than the chloroplatinic acid. It's readily absorbed through the skin and the dose needed is far smaller than lead alone because it's soluble in water. It's also easy to inhale when it's dissolving because of the bubbling since drops of solution are inevitably aerosolized. I'm aware that chloroplatinic acid is one of the most powerful skin and respiratory irritants known and aqueous lead aerosol is a good irritant due to it's ability to oxidize skin, but since it's also a powerful neurotoxin it is more dangerous. Though since I've never refined PGM's myself, I'm mainly going on my understanding of heavy metal toxins and general safety precautions.

 

[saadat68]

Hi
In another topic 4metals said for best result it is better drop Pt before dropping gold
So Is it better drop Pt with NH4Cl then drop gold with SMB or Ferrous sulfate?

Thanks

 

[FrugalRefiner]

Saadat, with all due respect, I suggest you DO NOT deal with platinum. There are very few members here who are equipped and knowledgeable enough to deal with platinum safely. Several members have become so allergic to it that they can not be anywhere near platinum salts anymore, and at least one very experienced member died from his exposure. PLEASE, stay away from the platinum group metals, for your own safety and that of those around you.

I will not answer any questions for you about the PGMs, and I hope other members will do the same.

Dave

 

[cuchugold]

Hi
In another topic 4metals said for best result it is better drop Pt before dropping gold
So Is it better drop Pt with NH4Cl then drop gold with SMB or Ferrous sulfate?

Thanks

If you really do have PGMs in quantity, then it's best to drop the gold with SMB, and then cement the PGMs with copper. This way you'll never deal with the PGM salts that are highly toxic. You can later sell the cemented powders to a professional refiner. Since you are asking the question, that's probably the best course of action for you.

 

[saadat68]

Thanks
Now I have a question about palladium and safety. You know in E-scrap recycling we dealing with this metal
I ask my question here

http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=51&t=18362&p=286630#p286630

If you really do have PGMs in quantity, then it's best to drop the gold with SMB, and then cement the PGMs with copper. This way you'll never deal with the PGM salts that are highly toxic.

But we have PGM salts in chloride solution ?
Right? Is it safe?

 

[DarkspARCS]

Saadat, with all due respect, I suggest you DO NOT deal with platinum. There are very few members here who are equipped and knowledgeable enough to deal with platinum safely. Several members have become so allergic to it that they can not be anywhere near platinum salts anymore, and at least one very experienced member died from his exposure. PLEASE, stay away from the platinum group metals, for your own safety and that of those around you.

I will not answer any questions for you about the PGMs, and I hope other members will do the same.

Dave

I got to this thread from the portion of it archived in the GRF library, which does not include the 3rd page of this topic, which therefore DOES NOT POSSESS THIS VERY IMPORTANT WARNING...

I've respected FrugalRefiner's advice for many years now, and have watched valued members like he discusses within this warning disappear.

RESPECTFULLY... CAN THE ADMINISTRATION PLEASE POST THIS THIRD PAGE TO INFORM THE NEWBS...

Perhaps creating a section of the Library categorizing HAZARDOUS PROCESSES that will enlighten the acolyte?

Thanx...