Cement

[jmdlcar]

When working with Nitric Acid what other metal will cement to copper beside Silver?

 

[Shark]

The precious metals will cement to copper. Gold, silver, platinum, and so on. I think in terms of simple language, but it has to do with the reactivity series of metals. Anything below a given metal will cement to that metal. Copper is right above the precious metals and that is why copper is the suggested metal when collecting mixed precious metals from a solution as well as a single one such as silver. One exception may be that copper will attract mercury. I am not very good at explaining this type stuff as I struggle at times to get things from my mind into words. I am sure someone better will correct me if I got it wrong, which is one of the great things about this forum.

 

[butcher]

Shark, you think you have trouble explaining things you should see me struggle with words, heck I am always getting E'm backards, or my mouth or fingers typing something different than what I have in mind to say...

You do a great job, my friend, Keep up the good work.

 

[jmdlcar]

When I process my Silver I didn't want to cement no other metal but my Silver. Is there any other metal that could get cement?

 

[Lino1406]

Unfortunately not

 

[nickvc]

If you are only working with sterling or coin silver you should have no worries, the other elements that will cement out include the precious metals are Mercury as mentioned and tungsten I believe so unless you suspect any of those metals you should be good to use copper, if you suspect those metals convert to chloride and then cement the spent solution.

 

[Martijn]

Theoretically speaking working with nitric and silver, I understood that some Palladium (if present) can follow silver in or out of solution, and Palladium itself is soluble in hot nitric acid. Cementing this solution will also bring down Palladium. Those two are separated by forming AgCl to keep Pd in solution if i'm right... if not, we'll here it soon.

 

[Shark]

A few other metals may follow along with the silver at times depending on the feed stock. This why a silver cell is used afterwards. Most things that will cement out with the silver will stay behind in the cell slime's or in the electrolyte. Sterling is pretty straight forward as mentioned, try processing some silver plate from an H2O cell. You get all kinds of stuff following along that changes the quality of the silver and the electrolyte, but it will clean up nicely if watched closely.

PS: Forgot to mention Happy Birthday to jmdlcar.

 

[jmdlcar]

@ Shark, Thank you.

 

[Geo]

Palladium is the next most common metal you will find in electronics. It will dissolve in nitric acid and cement out on copper.

 

[scrapparts]

Palladium is the next most common metal you will find in electronics. It will dissolve in nitric acid and cement out on copper.

That's what I need to learn. I have approximately 2 gal bucket of dried stock pot material that has accumulated using an air pump and copper. I am sure I have some PGM's in my powders from and my stock pot, now I need to know how to deal with each one separately from the same solution.

This site has great teachings for refiners and new refiners.

scrapparts

 

[nickvc]

Finding PGMs in e scrap is fairly uncommon to put it politely, the main use is in telecom equipment from what I understand but I’m sure they are used in other areas but not very often, this is far less true for soviet e scrap but most in the west will not get access to this material.
If you have been processing white gold jewellery scrap or white stone settings then maybe you have some PGMs in your stock pot.
Personally I’d forget PGMs and concentrate on recovering any gold, you can always test your solutions to check for any PGMs after precipitating your gold and if present simply cement and store as black powders until you have a volume worth worrying about.

 

[g_axelsson]

Palladium in e-scrap from 1980-2000 is fairly common (if you know where to look) and also in small amounts on newer scrap. Mostly in MLCC:s but also as plating on lead-frames and component legs. It is also used as a catalyst when making printed circuit boards.

But Nick's advice is a good one. Just go after the gold in the stock pot and then test the left over liquids. If it contains small amounts of PGM just add it to the next stock pot and let it build up over time. If you have a substantial amount of PGM in the left over liquid you could just cement it out on copper or zinc and collect the metal powder. In that form it isn't a danger any longer.

Göran

 

[Slochteren]

Theoretically speaking working with nitric and silver, I understood that some Palladium (if present) can follow silver in or out of solution, and Palladium itself is soluble in hot nitric acid. Cementing this solution will also bring down Palladium. Those two are separated by forming AgCl to keep Pd in solution if i'm right... if not, we'll here it soon.

Isn't possible to cement out palladium with a silver bar?

Verstuurd vanaf mijn STK-LX1 met Tapatalk

 

[Martijn]

I've asked myself the same question and have yet to find the answer: can you cement out pgm's with gold or silver? I ass.u.me. so...
Or pgm's on each other. And if so, what is the order of rectivity. Pure for the theory. It could help separating them.

 

[nickvc]

Once you realize that PGMs become partially or completely soluble with enough silver present in nitric then I think you have your answer, that’s why silver is recommended for inquarting as the PGMs follow the silver into solution and can then be recovered after cementation via a cell.
I believe the precious metals are all too close to each other for cementation to occur in any useful amount, perhaps one of our chemists can explain it better with the reasons.

 

[Geo]

Noble metals, with the exception of copper, is too difficult to oxidize to be used for cementing other precious metals. Palladium, when finely divided, will dissolve in HCl alone or nitric acid alone. It is difficult to cement out of solution because of it's tendency to redissolve in acidic solutions. I have found that to successfully cement Pd and keep it as a solid, you have to do one of two things. 1. Dilute the solution a couple times the original volume with water, or 2. adjust PH up to the point that the solution is not acidic enough to redissolve the powdered Pd. I have often fielded the complaint from people saying that after cementing with copper, the solution still tests positive for Pd. The Pd will redissolve about as fast as it cements from solution.

 

[g_axelsson]

I have often fielded the complaint from people saying that after cementing with copper, the solution still tests positive for Pd. The Pd will redissolve about as fast as it cements from solution.

Copper (II) chloride by it self is a powerful etchant that can dissolve palladium.
It's used in the Wacker process
https://en.wikipedia.org/wiki/Wacker_processSo cementing palladium from copper chloride with an air bubbler for agitation could easily dissolve the palladium again.

Göran

 

[scrapparts]

Finding PGMs in e scrap is fairly uncommon to put it politely, the main use is in telecom equipment from what I understand but I’m sure they are used in other areas but not very often, this is far less true for soviet e scrap but most in the west will not get access to this material.
If you have been processing white gold jewellery scrap or white stone settings then maybe you have some PGMs in your stock pot.
Personally I’d forget PGMs and concentrate on recovering any gold, you can always test your solutions to check for any PGMs after precipitating your gold and if present simply cement and store as black powders until you have a volume worth worrying about.

Understood. But if I have a stock pot that has copper in it and the copper doesn't dissolve anything else (I weigh the copper when I add to stock pot, then weigh as time goes by) does that mean that I MIGHT have PGM's in the cement dropped or are you saying that some of it dropped out of solution and some may still be in solution?


To g_axelsson,, I am glad you're on the forum. Again, I understand what you're saying, but what I'm not understanding is that if I process my stock pot, there is the possibility that PGM's could be in my solution, even after exhausting all the acids (copper won't dissolve anything) but still have copper left in the stock pot?

To both of you, .. I'll go for just the gold and silver FIRST. I did however recover the copper too, but never tested any of the solution to see if there were any PGM's still present.

I love you all here. I'm learning and keeping all of it close to my heart forever.

scrapparts

 

[Martijn]

Geo, you're full of knowledge I've never heard of before. Great new things to consider thanks to what you've pointed out!
E.g. the boiling of floating powder in H2SO4 , great tip. You should write a book! (or have you already?)

Back on topic: FeCl also is a powerfull etchant, can I expect that any of my 0,001ppm traces of cemented Pd from the iron displacement reaction in the waste treatment dissoved back into solution and ended up in the hydroxides? Or is FeCl not able to dissolve Pd cement?
I've searched the internet and did not find an answer.

If i'm not mistaken, FeCl can be formed in the waste treatment by adding a piece of iron to CuCl and such?
Where will the Pd end up if no special precautions are taken?
Not in the stockpot I presume, if there is Cu2Cl present, which usually is?
Again purely theoretical, I am not to worried about losing 0,001ppm :wink:
Martijn.