More specifically Sodium Hypochlorite.
Anything else you want to inform us about?
Problems in platinum recovery
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Anything else you want to inform us about?
You started out by saying this,
In your second quote you mention dropping the Palladium with salt. then later on you said;
The rinsing and addition of hypochlorite (or bleach, choose your terminology) can possibly reduce any Palladium the Silver Chloride may have dragged down.
How are you sure there is not additional Palladium in the mother solution, given the salt precipitation is not a well documented process and it may have only caused some of the Palladium to drop as a salt?
I realize you type slow, I too type with 2 fingers (with the thumb helping on the space bar) but I guess I can do it faster than you. I am not trying to pull out any guarded secrets from you but you did mention some process steps that can be questionable and I do not want to cause any members reading this to take it as doctrine without it being discussed fully.
There are too many missing parts to this for me. Nothing about what the starting material is or other PM's recovered and for now, until you clarify, it is just too big a pill for me to swallow.
and followed that up by saying this,
The 2 processes you have mentioned will produce different, if not questionable results. I am afraid that anyone trying to follow this thread will be thrown off without clarification.
In your second quote you mention dropping the Palladium with salt. then later on you said;
While I do not understand the mechanism for just table salt dropping the Palladium I will concur that Silver Chloride is notorious for dragging down other metals with it and possibly, in your case, Palladium is dragged down.
The rinsing and addition of hypochlorite (or bleach, choose your terminology) can possibly reduce any Palladium the Silver Chloride may have dragged down.
How are you sure there is not additional Palladium in the mother solution, given the salt precipitation is not a well documented process and it may have only caused some of the Palladium to drop as a salt?
I realize you type slow, I too type with 2 fingers (with the thumb helping on the space bar) but I guess I can do it faster than you. I am not trying to pull out any guarded secrets from you but you did mention some process steps that can be questionable and I do not want to cause any members reading this to take it as doctrine without it being discussed fully.
There are too many missing parts to this for me. Nothing about what the starting material is or other PM's recovered and for now, until you clarify, it is just too big a pill for me to swallow.
maybe you mean that they co-precipitate when you add salt to the solution of Pd and Ag in nitric acid (not in AR). I seem to remember that it also happened to me on one occasion.
thank you very much kurt and 4metals.
There were some things I didn't know like not using AR if PGMs are not the main metal, or that PGMs don't precipitate well in dilute solutions. Also the silver 10 times higher than the Pt so that it drags everything towards the silver part.
You are not aware of what a tremendous pleasure it is to read and learn from you.
I will reconsider everything you have told me and see again what path to take.
I come across platinum tunings more often than I would like and sometimes I don't understand why sometimes it turns out well and other times not so much.
So thanks again for providing your vision.
I take this opportunity to ask another question. I have noticed that sometimes the precipitate after adding ammonium chloride is yellow, other times orange, and even once I recovered it from a solution that had iridium it came out red. From what I have read, this depends on the temperature at which it is formed. But as I understand it, iridium precipitates black. The red I got was carmine red, it didn't look like a mixture of the orange powder and black. I leave a photo of the normal one, and that red that I tell you about. In case you can provide some valuable information through your experience.
Thanks guys
all images are ammonium hexachloroplatinate
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When refining platinum I always start with a concentrate made by cementation. The gold from all of the solutions containing Platinum is dropped with ferrous sulfate and the accumulated Platinum is processed in bulk. This is possible by paying for the metals in customer bars by assay and only processing the PGM's when they are in larger quantities. The method I always used was to mix up a super saturated solution of ammonium chloride in a volume equal to the volume of Platinum solution I have to treat. The Platinum solution I am treating is heated in a vessel large enough to contain the extra volume of adding all of the ammonium chloride solution, which is also hot.
The Platinum comes down quickly and after about 30 minutes I filter it off and rinse it in a solution of distilled water with 15% ammonium chloride added (W/V). That keeps any of the ammonium chloroplatinate from dissolving in the rinse. (ammonium chloroplatinate has a slight solubility in water). The Platinum salt I recover is always the yellow color as @100tific shows in the bottom (third) photo.
I have no doubt @Lou can shed some light on possible causes for the varying shades of yellow/red you have pictured as Lou deals extensively with PGM's.
The Platinum comes down quickly and after about 30 minutes I filter it off and rinse it in a solution of distilled water with 15% ammonium chloride added (W/V). That keeps any of the ammonium chloroplatinate from dissolving in the rinse. (ammonium chloroplatinate has a slight solubility in water). The Platinum salt I recover is always the yellow color as @100tific shows in the bottom (third) photo.
I have no doubt @Lou can shed some light on possible causes for the varying shades of yellow/red you have pictured as Lou deals extensively with PGM's.
I should point out that you really should not be drying the ammonium hexachloroplatinate like that. It is best to always handle it damp, with full PPE and preferably in a filter box. Then take a shower after!
That admonition aside, the color of the ammonium hexachloroplatinate you have shown and talked about indicates contamination. It's highly suggested to either dissolve the salt in aqua regia (or otherwise remove the ammonium cation) and complete a hydrolytic refining from oxidizing conditions, as described in 4metals other thread titled Bromate Hydrolysis. You do not need to use bromate, chlorine and caustic soda are use industrially. Bromate just happens to give a better result.
the iridate salt, which comes down substantially completely with the platinum from highly oxidized solutions, will darken your platinum precipitate orange to red. Palladium can also do this, and is far more likely.
That admonition aside, the color of the ammonium hexachloroplatinate you have shown and talked about indicates contamination. It's highly suggested to either dissolve the salt in aqua regia (or otherwise remove the ammonium cation) and complete a hydrolytic refining from oxidizing conditions, as described in 4metals other thread titled Bromate Hydrolysis. You do not need to use bromate, chlorine and caustic soda are use industrially. Bromate just happens to give a better result.
the iridate salt, which comes down substantially completely with the platinum from highly oxidized solutions, will darken your platinum precipitate orange to red. Palladium can also do this, and is far more likely.
When treating the solution with ammonium chloride it should be noted that platinum will come down first and then iridium will fall a short time later without you doing anything else to the reaction. This is why I mentioned 30 minutes. I typically siphoned off the majority of the liquid as soon as it settles and filter the rest. I have had success waiting as long as 30 minutes but if you let it go overnight any Iridium will be mixed in as well.
Please pay particular attention to Lou's advice about handling the powders, Platinosis is a serious illness which you can find information about HERE
Please pay particular attention to Lou's advice about handling the powders, Platinosis is a serious illness which you can find information about HERE
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Why does this forum update every so often and wipe out what you have painstakingly typed? Not so much on a computer but when you use a phone.
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Is better to chase the platinum from two solutions than the gold. If you inquart the gold too much below 25% then it too will follow the silver into solution. Inquarting with copper is gods way of punishing the cheap for being lazy. I tell my people all the time that procedure is written in order for a reason. Until and unless you understand why it is in the order as written it is best to not adjust unless you want to have a mess on your hands. This green solution is a mess and it is going to fight you for the value it contains. I know I will catch hell for this but if you are inquarting with copper then you are wrong. If you have to do it so be it, but its more expensive and will waste more material in the end. If your pgms will follow silver into solution, then why would they not follow copper?
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Sodium chloride in AR should not participate silver chloride under any circumstances. It would be created from the chloride in the hcl alone.
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The most economical way to handle this if you absolutely had to work with the copper diluted alloy would be to completely dissolve it in AR and then drop the gold. If smb was used to drop the gold you would need to let the solution rest in the open atmosphere for a few days to make sure the sulfur containing gases were gone from the solution.
Then cement the values so you can get a clean solution to work with when you add Ar again.
Then cement the values so you can get a clean solution to work with when you add Ar again.
Absolutely true.
I was so focused on the claim of precipitating the Pd that I completely overlooked the AgCl claim.
With amounts of platinum and palladium in material, I would suggest (as other experienced members suggested) to go for the gold and accumulate PGM residue for later processing. Working with PGMs is much more complex and tedious task, and it is best to combine the leftovers from multiple runs to save time and your sanitymaybe you mean that they co-precipitate when you add salt to the solution of Pd and Ag in nitric acid (not in AR). I seem to remember that it also happened to me on one occasion.
thank you very much kurt and 4metals.
There were some things I didn't know like not using AR if PGMs are not the main metal, or that PGMs don't precipitate well in dilute solutions. Also the silver 10 times higher than the Pt so that it drags everything towards the silver part.
You are not aware of what a tremendous pleasure it is to read and learn from you.
I will reconsider everything you have told me and see again what path to take.
I come across platinum tunings more often than I would like and sometimes I don't understand why sometimes it turns out well and other times not so much.
So thanks again for providing your vision.
I take this opportunity to ask another question. I have noticed that sometimes the precipitate after adding ammonium chloride is yellow, other times orange, and even once I recovered it from a solution that had iridium it came out red. From what I have read, this depends on the temperature at which it is formed. But as I understand it, iridium precipitates black. The red I got was carmine red, it didn't look like a mixture of the orange powder and black. I leave a photo of the normal one, and that red that I tell you about. In case you can provide some valuable information through your experience.
Thanks guys
all images are ammonium hexachloroplatinate
In PGM refining, ammonium hexachloroplatinate is something like silver chloride for refiners
If you really do not need to produce it, you avoid it and refine with other methods. If you do not happen to have nice tube furnance equipped with hydrogen cylinder for complete and convenient reduction to platinum sponge of course With this feed you have, I will probably go with dissolution in AR as you did, AgCl bulk filtration, then gold precipitation.
Leftover liquid containing PGMs would be then cemented (either with appropriate amount of iron or with copper) to concentrate values (this will allow you to skip evaporation) as metallic powders.
And from there, you can either process them (nicely concentrated feed = easy to do) either cumulatively or individually (each batch separately).
If you need to somehow clean the PtPd and resolve it to Pt and Pd part, good and easy method to use is to de-NOx the solution to get rid of any leftover oxidizing species and precipitate palladium with ascorbic acid. Silver and also some copper will follow, but co-precipitation of platinum is minimal. It needs pH adjustment (which also usually lead to one necessary filtration of eventual hydroxides precipitate) to around 1 to work OK. There are threads discussing the ascorbic reduction of Pd on the forum. Relatively Pt free palladium powder will be obtained, and liquid will contain reduced Pt(II) species alongside with majority of base metals.
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Maybe I missed it, but is there a reason why you isolate platinum and palladium from feeds ? From my experience, if you don´t produce high purity added value products from PGMs (like catalysts, pure PGM salts, pure PGM metal wires/sheets etc.), I see no benefit in refining these quantities of metals yourself. Melt the enriched PGM leftover from cementation (this should have very decent PGM content) and sell it to larger PGM processors. In small quantities, your time as employee can be sometimes more valuable than money you can make selling 99% pure PGMs.
Abdoulapapatte
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hello I just put my two cents here, I read you and I learned a lot, personally I never went through aqua regia if AG Above 7%, too many jokes in the past, too much loss and too much processing time afterwards (to be avoided and prohibited).Nitric acid dissolves platinum in small concentrations ????
oh good??
why then do I find the exact grammage even when it's 3gr per kg?? especially in silver blocks that I etch with nitric 65%?
Unless I'm not washing properly, which is possible because I was never allowed to breathe in boulor, I find that with NH4Cl I usually get pure platinum at 996.5/1000. never 999.9 (DAMN!)
for my part and fans of your case, I would have :
1) passage HNO3 -----> Ag and Pd degage
2) filtration -----> Ag/Pd filtrate / retained solid: Au/Pt
3) The filtrate would then be treated in several ways depending on your equipment:
a) precipitation on Cu -----> melting ----> shot blasting-> Ag cell
Ag recovery in 999.9 and Pd recovery in “sludge”.
I'd do a silver cell electrolyte test especially if green tint, if pd present then Dmg and recovery.
to finish, sponge and pd sludge in AR----> precipitation on Cu or zinc powder works very well.
b) Add HCL OR NaCl ---->Ag recover in agcl form ----> Naoh---->glucose----> Ag 999.9 IF rinse well and compress after each wash, to avoid precipitate of Agcl you have to mix several times, its structure changes and it becomes finer, you have to let it rest and filter it, it is important to be meticulous.
image way b)
Pd solution remains ------> Cu precipitation, OR DMG or wholtech method.
4) Coming back to the Au/Pt solid not attacked by HNO3, I'd like to point out that platinum is never attacked in my laboratory, perhaps because I always add enough H2O to cover the alloy to be attacked before adding the nitric acid, perhaps because the nitric acid dissolved in this way doesn't attack it (something to think about).
Take your solids, wash well with distilled H2O several times.
Once well washed, I check for any trace of Agcl still present by adding a little Hcl to the distilled water I used to wash the remaining solids. If Agcl is still present, wash again with hot water.
5) passage of solids in AR, another small detail,
I never prepare aqua regia 1/4 HNO3--3/4 HCL (c'est bon pour les durs à cuire) ici on recherche la finesse, l'élégance et la clarté. Bref, soyez un vrai gentleman cambrioleur.
SO put enough HCL 37% (muratic acid) that you think you need, and THEN add little by little HNO3 repeatedly, until complete dissolution.
SO put enough HCL 37% (muratic acid) that you think you need, and THEN add HNO3 little by little repeatedly, until the solids are completely dissolved. Why I do this, to simply avoid having to denox HNO3. I therefore approach the stoichiometric quantities
6) After that, nothing could be simpler when you find yourself dear friends with your liquor containing dissolved Au and Pt, you can therefore proceed in 2 different steps:
a) ajouter du sulfate de fer (II = vert) pour précipiter l'Au----> filtration----> lavage avec HCL 37%-- deuxième filtration -----> lavage à l'eau distillée ----> séchage ---> fonte. L'Au est sorti OUI !!!!!
There will therefore only be the platinum left and you can precipitate it with ammonium chloride, before precipitating it you can also add hydrochloric acid, which you used to rinse your gold, in fact it sometimes happens that a little platins follow Au, it is therefore found in hcl that you used to wash it.
To turn your platinum sponge into metal you can either heat it delicately, slowly to avoid losing any, then once it is very black, melt it, or redissolve it and this time precipitate it with formic acid.
here is the appearance of my sponge, 996.5/1000
as I do not like to lie and I love to share my discoveries it is often accompanied by results in order to prove the veracity of my results and what is so lacking in your forum, people put forward hypotheses without controlling their results .
small contamination Pd Rh because waiting to much time before filtration
my face : always work with security , becareful about Pt et Pd sponge.
I would like to make an interesting remark, there is no one on the forum who has taken the time to explain how to correctly refine platinoids and I find that really shameful, I would like the main speakers to take the time to do so a thread on this subject whether in the patent or library section, I am sure that some have the knowledge, the knowledge and the adequate tools to do it so wait you stop keeping your secrets in a cupboard, we must move forward together, and even if your boss forbids you to do it, break the silence, it is not us who are going to compete with an LBMA or any foundry lost on the other side of the world, so advice to the specialists hiding and not sharing, help us progress
see you
oh good??
why then do I find the exact grammage even when it's 3gr per kg?? especially in silver blocks that I etch with nitric 65%?
Unless I'm not washing properly, which is possible because I was never allowed to breathe in boulor, I find that with NH4Cl I usually get pure platinum at 996.5/1000. never 999.9 (DAMN!)
for my part and fans of your case, I would have :
1) passage HNO3 -----> Ag and Pd degage
2) filtration -----> Ag/Pd filtrate / retained solid: Au/Pt
3) The filtrate would then be treated in several ways depending on your equipment:
a) precipitation on Cu -----> melting ----> shot blasting-> Ag cell
Ag recovery in 999.9 and Pd recovery in “sludge”.
I'd do a silver cell electrolyte test especially if green tint, if pd present then Dmg and recovery.
to finish, sponge and pd sludge in AR----> precipitation on Cu or zinc powder works very well.
b) Add HCL OR NaCl ---->Ag recover in agcl form ----> Naoh---->glucose----> Ag 999.9 IF rinse well and compress after each wash, to avoid precipitate of Agcl you have to mix several times, its structure changes and it becomes finer, you have to let it rest and filter it, it is important to be meticulous.
image way b)
Pd solution remains ------> Cu precipitation, OR DMG or wholtech method.
4) Coming back to the Au/Pt solid not attacked by HNO3, I'd like to point out that platinum is never attacked in my laboratory, perhaps because I always add enough H2O to cover the alloy to be attacked before adding the nitric acid, perhaps because the nitric acid dissolved in this way doesn't attack it (something to think about).
Take your solids, wash well with distilled H2O several times.
Once well washed, I check for any trace of Agcl still present by adding a little Hcl to the distilled water I used to wash the remaining solids. If Agcl is still present, wash again with hot water.
5) passage of solids in AR, another small detail,
I never prepare aqua regia 1/4 HNO3--3/4 HCL (c'est bon pour les durs à cuire) ici on recherche la finesse, l'élégance et la clarté. Bref, soyez un vrai gentleman cambrioleur.
SO put enough HCL 37% (muratic acid) that you think you need, and THEN add little by little HNO3 repeatedly, until complete dissolution.
SO put enough HCL 37% (muratic acid) that you think you need, and THEN add HNO3 little by little repeatedly, until the solids are completely dissolved. Why I do this, to simply avoid having to denox HNO3. I therefore approach the stoichiometric quantities
6) After that, nothing could be simpler when you find yourself dear friends with your liquor containing dissolved Au and Pt, you can therefore proceed in 2 different steps:
a) ajouter du sulfate de fer (II = vert) pour précipiter l'Au----> filtration----> lavage avec HCL 37%-- deuxième filtration -----> lavage à l'eau distillée ----> séchage ---> fonte. L'Au est sorti OUI !!!!!
There will therefore only be the platinum left and you can precipitate it with ammonium chloride, before precipitating it you can also add hydrochloric acid, which you used to rinse your gold, in fact it sometimes happens that a little platins follow Au, it is therefore found in hcl that you used to wash it.
To turn your platinum sponge into metal you can either heat it delicately, slowly to avoid losing any, then once it is very black, melt it, or redissolve it and this time precipitate it with formic acid.
here is the appearance of my sponge, 996.5/1000
as I do not like to lie and I love to share my discoveries it is often accompanied by results in order to prove the veracity of my results and what is so lacking in your forum, people put forward hypotheses without controlling their results .
small contamination Pd Rh because waiting to much time before filtration
my face : always work with security , becareful about Pt et Pd sponge.
I would like to make an interesting remark, there is no one on the forum who has taken the time to explain how to correctly refine platinoids and I find that really shameful, I would like the main speakers to take the time to do so a thread on this subject whether in the patent or library section, I am sure that some have the knowledge, the knowledge and the adequate tools to do it so wait you stop keeping your secrets in a cupboard, we must move forward together, and even if your boss forbids you to do it, break the silence, it is not us who are going to compete with an LBMA or any foundry lost on the other side of the world, so advice to the specialists hiding and not sharing, help us progress
see you
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Nitric will not touch Pt, unless it is alloyed with Silver.
If you have an alloy with Silver, 1 to10 Pt Silver, the Nitric will dissolve the Pt completely.
Hozzy
New member
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Hi there,
Thanks for sharing your process! The green scab you observed is likely CuCl₂ (Copper(II) chloride), formed due to the high copper content reacting with chloride ions in aqua regia. This can happen if the reaction slows or becomes less acidic over time.
To confirm, dissolve a small amount in water—CuCl₂ is water-soluble and turns the solution green.
Since copper is dominating, it might interfere with dissolving other metals. You could filter the residue and consider removing excess copper (e.g., via cementation with iron) before continuing with platinum and gold recovery.
Let me know if you need further tips!
Thanks for sharing your process! The green scab you observed is likely CuCl₂ (Copper(II) chloride), formed due to the high copper content reacting with chloride ions in aqua regia. This can happen if the reaction slows or becomes less acidic over time.
To confirm, dissolve a small amount in water—CuCl₂ is water-soluble and turns the solution green.
Since copper is dominating, it might interfere with dissolving other metals. You could filter the residue and consider removing excess copper (e.g., via cementation with iron) before continuing with platinum and gold recovery.
Let me know if you need further tips!
Welcome to us.
This thread is over 3 pages long and as such it is hard to know who(which post) you are addressing.
It is much better to use the reply to link, this way your answer will contain a quote of the post and a link back to it.
Like this:
On the other hand Copper will not "interfere" with dissolving other metals.
It will consume more Nitric which is true and as long as you dissolve it all it will not cement out the precious metals.
If it is doable or practical, we recommend dissolving the base metals first.
And then go for the precious metals.
I am fascinated by your explanation, thank you very much. I think your Pt never follows nitric because the amount of silver is not 10 times greater than that of platinum.
Normally I use sodium metabisulfite to precipitate the gold instead of iron sulfate, I suppose it will not significantly affect the result. but what do you think?
I have seen that the method you use to recover silver is electrolytically. I have an electrolytic cell to recover the silver, but we do several recoveries there and when I extract PGMs I like to make each batch individually, I would not like to put those liquids where we put the rest and I would prefer to treat them individually. So the method I will use to separate Ag and Pd in a single batch would be NaCl or HCl to the liquid after the HNO3. I would like to know if, when we add NaCl or HCl to the liquid, Pd and Ag coprecipitate or is it selective for Ag only. Because on one occasion this gave me problems. I tried to separate them and there was no Pd left in the liquid and the AgCl had a pink tone. I think I solved it by adding HNO3 back to the precipitate. I would like to discuss this if anyone has any knowledge.
I am trying to know "the method" to be able to separate precious metals having any alloy. Compiling all information and with the equipment and material I have available.
I have already bought more safety clothing, masks that cover my entire face and jackets. I have also bought copper powder.
I would like to show you how I do it and when I receive all the material and the results I obtain.
Meanwhile I continue studying, I continue reading, all information is welcome, and thank you again.
