palladium from nitrate solution

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Very interesting and I think it is needed to reread this some more times to understand all consequences, I at least will have to.

Göran, I can hardly believe you didn't try the sugar method for silver chloride, so, what did you make chosing this way (chloride-oxide-nitrate-cementation)?
 
butcher said:
Although metals do precipitate as hydroxides the range they do so can vary widely, it is not that they get to a certain pH and then just drop out of solution.

My guess here is when you bring the pH up closer to neutral (pH 6 to 7) some of the silver will precipitate as an hydroxide of silver, but much more when you get into the pH of around 9, all the way up to around pH 12 where the silver hydroxide will be the least soluble as a hydroxide.
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Correct - after adjusting the Ag nitrate to the near neutral I put a drop in my jar that contains HCl which I rinse my Ag nitrate beakers into to recover the traces of very dilute Ag in as AgCl & yes there is still Ag in solution so at near neutral some of the Ag starts to precip but it doesn't bring it all down - how high on PH you would need to go to get it all is another story

How concentrate (or dilute) is going to make a difference - as well as temp --- I figured this all out when testing Ag nitrate solutions with DMG that is prepared with NaOH - if the solution would get to dilute the NaOh would precip Ag (as well as Pd if present) but the Ag would not go back into solution like in a concentrated Ag nitrate solution

Anyway the point I was trying to make to Marco was that in order to precip Pd from a nitrate solution it is not as simple as just adding SMB &/or bubbling SO2 into the solution - but rather it requires PH adjustment & therefore other metals can become a problem - & PH adjustment is only part of it

Kurt
 
solar_plasma said:
Very interesting and I think it is needed to reread this some more times to understand all consequences, I at least will have to.

Göran, I can hardly believe you didn't try the sugar method for silver chloride, so, what did you make chosing this way (chloride-oxide-nitrate-cementation)?
Click to expand...
I did try the sugar method and I felt it was messy. The way I'm doing it now suits me fine, my metallic silver powder is free from silver chloride. I never got a 100% conversion with sugar and the remaining silver chloride annoyed me. Also the waste liquids are opaque and I can't see if there are any sediments or the filtrate is clear.
If I do silver chloride my way I can filter / decant off the silver nitrate and any remaining silver chloride would be exposed when the nitric dissolved the silver oxide so I can repeat the process if there's enough left or just add it to the next batch.
One good thing is that I don't need to wash the silver in ammonia to remove silver chloride and all the inconveniences that brings.

The waste liquid can be put into the stock pot for cementing traces of pgm:s and collection of silver chloride. Any NaOH will be neutralized by the next addition of acid waste. I don't want to add any organics to my stock pot so the waste from the sugar method I would have to process separately.

Maybe I'm going to give the silver chloride and sugar method another go if I have a lot of silver chloride without traces of other precious metals, but currently the only silver chloride I get is from electronic waste and lot sizes are usually between 10 and 100g. A small beaker, treat it with NaOH, then washing and treating it with a few ml of nitric acid, then on to cementation, drying and adding it to my recovered silver powder.

When I have enough silver powder I'm going to run it through a silver cell to separate any PGM:s that have hitched a ride.

Göran
 
solar_plasma said:
Very interesting and I think it is needed to reread this some more times to understand all consequences, I at least will have to.
Click to expand...

Solar

You will need to dig deeper then just this thread to even start to understand it (Pd in a nitrate solution) I have recently been doing a fair amount of research on it & still don't have my head wrapped around it - at least not to the point of playing with it yet - though I have learned a lot - at this point I need to start going over my notes & putting some order to them

Kurt
 
Kurt, you're absolutely right and I am aware of it. After my first and only adventure with platinum, which worked, but I learned how messy it is, I am still not sure, if I ever want to get back to pgms. No, I was thinking of hydroxide precipitation in general. Reading all the texts here and on the net, one could easily get the impression, that it would work fine for parting base metals - nope, it won't, at least not to any point of satisfaction in most cases other than to show pupils one of many ways to treat industrial waste. At least this is my opinion today.

Göran, I knew, there must be a reason, why you chose this way. I appreciated the sugar method for making less volume of waste and not having to mess around with HNO3 more than absolutely necessary.
 
When I started, I wanted to learn it all and if possible all at the same time. I got wiser. It's okay with microexperiments showing to the pupils, but every single process creates its own kind of waste. Specializing to a few processes saves me a lot of headache, I learned :lol:
 
solar_plasma said:
When I started, I wanted to learn it all and if possible all at the same time. I got wiser. It's okay with microexperiments showing to the pupils, but every single process creates its own kind of waste. Specializing to a few processes saves me a lot of headache, I learned :lol:
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:lol:

One of the things I like about all of this is just about the time you think you have it all figured out - you find out your not even close :mrgreen:

My experience on this forum over the last 4 years has been :arrow: :shock: 8) :lol: :x :p :oops: :cry: :evil: :twisted: :roll: :!: :?: :idea: :| :mrgreen: (did I miss any of them there faces)

Kurt
 
kurtak said:
solar_plasma said:
When I started, I wanted to learn it all and if possible all at the same time. I got wiser. It's okay with microexperiments showing to the pupils, but every single process creates its own kind of waste. Specializing to a few processes saves me a lot of headache, I learned :lol:
Click to expand...

:lol:

One of the things I like about all of this is just about the time you think you have it all figured out - you find out your not even close :mrgreen:

My experience on this forum over the last 4 years has been :arrow: :shock: 8) :lol: :x :p :oops: :cry: :evil: :twisted: :roll: :!: :?: :idea: :| :mrgreen: (did I miss any of them there faces)

Kurt
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That's OK. you will find as you do it even longer and handle even more different item that you know even less but it does come together slowly with time. :p
 
Thanks to you all I came to stick in my tick skull that, for now, I've got to eliminate silver before palladium or use DMG first, and then cement silver for last. After all the expected return should be ≤20%, remember this is a 8:2 Ag:pd alloy.

I might also look into separating silver chloride, quickly switch from nitric to chloride at 80°C (176°F) by addition of hydrochloric [stt]and cotton balls. I believe putting a layer on top of the solution would also catch and suppress some NOx perhaps a slight excess would also behave as flocculant?[/stt]
Anyway after denoxing I could go the well known way as per Ms Hoke.

I never would have thought to have to deal with such quantity of palladium so early, e-waste will return much less.
 
g_axelsson said:
For treatment of silver chloride I usually treat it with NaOH to turn it into oxide / hydroxide, then dissolving it in nitric acid and cementing it with copper. Any leftovers of silver chloride is caught in filters and ends up in my burn pile for later processing.

Göran
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Goran

thanks for the tip - I have always disliked the sugar part of the AgCl conversion for the same reason (sugar in the waste) I think I will give this a try the nexttime I am dealing with AgCl

when I think about it (now that you mention it) its like a "no brainer" -at least for small amount of AgCl

Kurt
 
Just for the completeness, silver oxide can be reduced with H2O2, too.

Here is one link for those who are interested: EDIT: and to those, who do not read the answers below: Lou says, don't use this, because of possible steam explosions

http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=50&t=19249

I tried it once with a few gramm, but sugar is cheaper to me. For many it is getting harder to buy H2O2.
 
NEVER reduce silver oxide with hydrogen peroxide.

Too exothermic and likely to cause steam explosions. Silver catalytically decomposes peroxide.

Horrible idea for larger scale work.
 
You are correct Lou, now I remember that many semi professional rockets use a silver catalyst and hydrogen peroxide as the sole fuel. That's all!

Thanks for the warning!

This is what you get when mixing hydrogen peroxide with a silver catalyst. (Cut to 1.47 to get to the action)
[youtube]http://www.youtube.com/watch?v=hWxjUDEYIiw&x-yt-cl=84503534&x-yt-ts=1421914688#t=10[/youtube]

Göran
 

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