How to extract silver from gold and platinum?

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Joined
Mar 29, 2011
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8
Can anyone tell me how to extract silver from gold and platinum? I just want to know about it. Is anybody there, who tells me what to do for it.
 
jeneje said:
Hello,
4metals I through pt group metals had to be heated with AR to dissolve in solution.

Ken
What 4metals told you is correct. If you have an alloy of silver and platinum, both constituents will dissolve readily in nitric acid. You can make that determination yourself by dissolving some of the material and testing with stannous chloride.

In order to recover platinum that is contained in silver, it is recovered from the slimes from a silver parting cell.

Harold
 
I have 70 grams of silver bar. I think that It has 14% of pure platinum.
Now I want to know how much nictic acid I use to dissolve silver to get pure platinum.
Except it, You can give any other suggestion If you have................
 
Platdigger said:
I believe you could run this bar directly in a silver cell.
And as Harold just said, the pt and also any gold should end up in the slimes.
The high percentage of platinum is likely to be troublesome, especially considering there's gold in addition. In order to successfully part in a silver cell, one may have to add a given amount of pure silver, to lower the overall percentage of non-silver material. As is typical of electrolytic cells, a silver cell will perform best when fed high purity.

I'm speaking from experience in this regard. When I processed the silver that was recovered from my waste material, the platinum, palladium and gold was too high to part the silver successfully. The slimes accumulated as a hard crust instead of loose particles that shed readily. Even with hard scraping, it was difficult to part the anode. Had I known the percentage was so high, I'd have followed my own advice, but I had but one anode to part, so I just toughed it out once I was committed.

Because of the heavy coating of slimes, I managed to deplete the silver in my electrolyte to the point where I began co-depositing palladium. I theorize that the silver was unable to penetrate the coating, although it was still very conductive. I liken the situation to one where silver chloride isolates gold alloy from AR, making it difficult to impossible to dissolve.

While the percentage of palladium that was co-deposited was obviously quite low, it wasn't acceptable to me, so after parting the last of the heavily contaminated anode, I simply placed the recovered crystal silver back in the cell, then added an anode on top to act as a connector. I re-parted the crystals, achieving an acceptable product.

Harold
 
Nitric acid did nothing with this silver bar which has approximate 14% pure platinum.
Nitric didn't solute the silver part. I have left this bar about 3-4 hours in nitric acid.
But it did not work. Is there anybody to tell me cheap and successfully way to do this.
I want to extract platinum from silver bar at any cost. I am very eager to do this.
All information about my query has been mentioned above my post........ :?:
 
Harold just gave you your answer. Looks like you are going to have to remelt, and add more silver.

"In order to successfully part in a silver cell, one may have to add a given amount of pure silver, to lower the overall percentage of non-silver material"
 
Also consider that you're using a bar. It has very low surface area relative to its volume. If you could make it into shot, that would greatly help.

Generally, the less melting/shotting and mechanical manipulation you do, the better accountability and yield will be.
 
Do note, also, that nitric acid alone does not dissolve silver well. You are best served using dilute nitric. In this case I'd advise distilled water----and modest heat if you don't get a quick reaction.

You're wasting your time trying to separate platinum by dissolving with nitric. Did you not pay attention to what you were told? When you have silver and platinum alloyed, both will dissolve in dilute nitric, so you won't accomplish your task.

Harold
 
Harold_V said:
When you have silver and platinum alloyed, both will dissolve in dilute nitric, so you won't accomplish your task.

Harold

Didn't know this. So the platinum won't drop as a sponge? How is platinum digested without HCL?
 
dissolve Pt/Ag in Nitric 50/50 - adding enough Ag to increase the Ag content % to over 90%
cement with Cu
melt into Anode
part in silver cell
recover silver from cell
remaining slimes = possible Pt

i think?
 
goldenchild said:
Harold_V said:
When you have silver and platinum alloyed, both will dissolve in dilute nitric, so you won't accomplish your task.

Harold

Didn't know this. So the platinum won't drop as a sponge?

In my opinion, no. Because both silver and platinum are in solution, if you tried to cement (using zinc flour, which would yield a sponge of sorts), both would come down. Lou may be able to shed a lot more light on this, as I am not a chemist.

What would work is to precipitate the silver as silver chloride, which could then be washed relatively free of any contained platinum (still in solution). The resulting solution might then be concentrated and processed for platinum, recovering by zinc flour or precipitating with ammonium chloride.

How is platinum digested without HCL?
I am unable to address that question, but know it to be true in practice. Lou may be able to provide the reason-----but if memory serves, it is discussed in Hoke's book as well.

Harold
 
dcurzon said:
dissolve Pt/Ag in Nitric 50/50 - adding enough Ag to increase the Ag content % to over 90%
cement with Cu
melt into Anode
part in silver cell
recover silver from cell
remaining slimes = possible Pt

You are making life hard on yourself. If I understand this correctly you are adding silver to your Ag/Pt alloy to bring the Pt under 10% so the Pt will go into solution in nitric. Then after you digest your new alloy you are cementing it on copper. What have you gained, as both will cement on the copper? When you melt this cement into an anode you will have what you started with before you digested it in nitric.

Having said that, if you have a bar that is over 10% platinum and the balance is silver, just re-melting it and adding the required silver to get 10% or less Pt does not make it suitable for a silver cell anode. A 10:1 ratio of Ag:pt should get all the Pt to go into solution with a nitric digest, but if you put that into a silver cell you will have a pacification layer build up on the bottom of your anode (as Harold said above) that will cause you much grief. If you want to alloy Ag/Pt for a silver cell I would not want the Pt over 3%.

On another note, readers should take to heart what Harold said about diluting concentrated nitric for silver. You can put a pure silver round into 70% nitric and it will just sit there and smile at you. Add a bit of water and it will digest with a vengeance. More or stronger is not always better.
 
Oz said:
dcurzon said:
dissolve Pt/Ag in Nitric 50/50 - adding enough Ag to increase the Ag content % to over 90%
cement with Cu
melt into Anode
part in silver cell
recover silver from cell
remaining slimes = possible Pt

You are making life hard on yourself. If I understand this correctly you are adding silver to your Ag/Pt alloy to bring the Pt under 10% so the Pt will go into solution in nitric. Then after you digest your new alloy you are cementing it on copper. What have you gained, as both will cement on the copper? When you melt this cement into an anode you will have what you started with before you digested it in nitric.

Not making life harder for myself as i'm not the one doing it, just gave a brief outline of what (i thought) might possibly be the route to take. The OP suggested there was Au in the alloy as well as Pt/Ag, dissolving in Nitric would take the Au out of the alloy and leave it in the bottom of the Nitric, leaving just the Ag and Pt to seperate via silver cell.

i must point out that i am vastly inexperienced and the likes of Harold, GSP, LaserSteve, Oz and others between them seem to have come across pretty much every possible scenario and should be listened to!
 
Oz said:
On another note, readers should take to heart what Harold said about diluting concentrated nitric for silver. You can put a pure silver round into 70% nitric and it will just sit there and smile at you. Add a bit of water and it will digest with a vengeance. More or stronger is not always better.
Once again I am at the mercy of my lack of education, but those with questions about the addition of water to nitric acid being valid in the dissolution of silver should explore the hydronium ion.

Harold
 
Harold,
I come from the same school as you do. Reading, due diligence, cause and effect. I too have not researched the hydronium ion to the point I can wrap my mind around it. I would enjoy hearing someone with knowledge explain it, but at the end of the day I have heeded others advice and proven it sound by my own experiences as to nitric concentrations.

Probably the greatest mistake made by those new to refining is too much nitric no matter the procedure or source.
 

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