Sulfamic acid silver cell?

rolynd

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Hi guys, do any of you know about someone that uses sulfamic acid as electrolyte in a silver cell? Anyone done that?
I am not much into refining I come from a Jewellery background. Due to difficulties in procuring nitric in the EU and my desire to etch silver I use a method that is able to electrochemically dissolve silver with 99 pure sulfamic acid in aqua dest as electrolyte. This works very well for my purpose (etching)and I also noticed that the dissolved silver collects as a greyish sponge at the cathode where it can be filtered off and reclaimed.
The next jump was - why not use that method for refining silver? At least on a small scale. I dont think that this will be useful for commercial rigs or large scale operations - the solubility of silversulfamate is - compared to silvernitrate- relatively low, but still an order of magnitude above other silver salts. (Solubility of silversulfamate 100g/l at 25°C. ) Sulfamic is easy to get, cost here is about 3,5€-5€ per kg depending on how much per order. Nitric is probably cheaper if you get it by the barrel but if you can get no nitric nor nitrates to make some at all - its a viable alternative at least.

In a silvernitrate based cell silver will collect at the cathode as fine silver up to a copper content of about 60g/L or such AFAIK- Does anyone know if thats true for a sulfamic acid electrolyte too?

The other idea I have, if copper is codeposited even at low overall content at the cathode would be the use of a divided cell with a conductive agar bridge or a membrane and then just dropping the silver as silverchloride from the anolyte and go from there. but that would be more hassle overall.

Yes I did use the search function, but all it came up with was the use of sulfamic as a denoxxing agent.
So far I use a sulfamic acid electrolyte only to etch silver and filter off the stuff that collects at the cathode. I am not doing large batcheslots of pieces but rather make a new electrolyte fresh when needed. so even while the anode is sterling there isnt much time for copper to go into solution in large quantities. from other posts and vids on silver cells I noticed that to get some nice and shiny silver crystals forming at least a noticeable amount of copper needs to go into solution at first- thats right? So I (maybe wrongly) assume that the silver at the cathode is more like a greyish spongy mass instead of solid silver crystals because there is no decent copper build up in the solution ?

Well, all these questions probably can be easily solved by more experiments and sending the reclaimed silver out for assaying - but before doing that I simply wanted your opinion on that topic - as said I am no refiner. All I see is I can dissolve silver fairly easily at the anode and then collect some at the cathode and that without nitric or nitrates needed.- my focus is more on my etched pieces - but the possibility of small scale refining just came to mind for processing small quantities of scrap thats always present in a jewellers studio.

silver-cathode.jpg
 

g_axelsson

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First time I hear about silver refining with sulfamic acid. A bit of searching revealed this patent.
https://patents.google.com/patent/US3616332A/en
Maybe that contains some useful information.

Göran
 

nickvc

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If it works it may well be able to strip plated material which to many is too much hassle to bother with.
 

rolynd

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thanks göran, that patent was particularly helpful. if the information is correct then silver will deposit as fine silver up to a conc of about 70g/l. not sure though if the use of glutamic acid has some influence on that.

What stumped me was that the sulfamic acid electrolyte remained clear throughout the whole etching process. usually dissolved copper compounds cause a blue or bluegreen tint thats what happens in the silvernitrate electrolyte at least. but maybe there wasnt enough copper in solution to color the electrolyte since only little material is removed during etching.
 

Topher_osAUrus

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Interesting post.

May have to try running some silver plated material in it to see how it fairs. I'm sure some substrates will do better than others. Although, that is just pure speculation, as I have no idea about the solubility of baser metals in sulfamic, except for what the container tells me to keep the acid away from.
 

goldsilverpro

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I didn't search for it, but, about 30 years ago there was a government RI, a Report of Investigation, from the Bureau of Mines (I think) that used a sulfamic acid electrolyte to recover silver from the stainless (I think) honeycomb inside the flaps of certain aircraft. If I remember right, there were many, many ounces in one flap. I'm also thinking the government had a patent on the process. If I get some time, I'll look for it
 

Rachello

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Sulfamic Acid is categorized as a Zwitterion formed ion. Or a hermaphroditism of 2 ions, one being positive & one being negative which results in the net charge of zero.

The use in a silver cell is an experiment I can not wait to implement. Although I have prior plans for today, my next test will be based on the posts above.

Too much work & no play...you know the rest! I am on my way to the junkyard for the day to scavenge treasures :D

Rachel
 

Rachello

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goldsilverpro said:
I didn't search for it, but, about 30 years ago there was a government RI, a Report of Investigation, from the Bureau of Mines (I think) that used a sulfamic acid electrolyte to recover silver from the stainless (I think) honeycomb inside the flaps of certain aircraft. If I remember right, there were many, many ounces in one flap. I'm also thinking the government had a patent on the process. If I get some time, I'll look for it

I know Sulfamic acid has been tested for a more environmentally safe solution to prior de-icing agents in the airforce. I believe they started testing Sulfamic acid as a de-icer on fighter aircraft in 1998, but please don't quote me on it. I have a document in my cue I've yet to read, but your post reminded me of it.

I'll post a link: http://www.dtic.mil/dtic/tr/fulltext/u2/a580819.pdf

I also think this is a good read: https://thesis.library.caltech.edu/4369/

It might help or might not but In the end it's all really cool stuff. :wink:

Rachel
 

Rachello

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Hey Goldsilverpro,

Did you ever dig up that RI? Im kind of obsessive about everything that has to do with conspiracy, mystery, science & space. Your post rang more than one of my bells :shock:. Most of all I hate unanswered questions, lol all of my above obsessions :D. If you get an extra minute dig it up! I would love to read it & the fact that it might have something to do with the USBM (assuming it's the US) along with the above! This is one of the very few posts that always return to my mind when I am trying to sleep :?:

No rush. I just have been thinking about your report like its 1999! Cue Music, Thanks Prince! Or maybe Area 51 & all its over-obsessed mysteries, & Theoretically The King might live!

Car je fais ce que l'humeur me commande et ce qui me donne de la joie.

Rachel
 

goldsilverpro

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Rachello said:
Hey Goldsilverpro,

Did you ever dig up that RI? Im kind of obsessive about everything that has to do with conspiracy, mystery, science & space. Your post rang more than one of my bells :shock:. Most of all I hate unanswered questions, lol all of my above obsessions :D. If you get an extra minute dig it up! I would love to read it & the fact that it might have something to do with the USBM (assuming it's the US) along with the above! This is one of the very few posts that always return to my mind when I am trying to sleep :?:

No rush. I just have been thinking about your report like its 1999! Cue Music, Thanks Prince! Or maybe Area 51 & all its over-obsessed mysteries, & Theoretically The King might live!

Car je fais ce que l'humeur me commande et ce qui me donne de la joie.

Rachel
I have had no luck in finding it. For some reason, those old RIs are hard to find. I used to be on their mailing list and, at one time, I had 100s of them.
 

Rachello

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Ugh! I hate to be on mailing lists! The emails are so numerous most of the time I get fed up & I just end up ignoring them! Then block b/c it’s soooo much spam :x
Until I need one & then... :eek: ....
It’s a love-hate relationship...

Rachel
 
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