Silver Recovery

[CBG]

I agree steel wool, but if you want to get good silver to make silver nitrate then just plate it out, that@s the easiest.

Assuming it's small scale then just rig up a rechargeable battery around 5 to 6 volts with silver wire for the anode and a carbon rod cathode.

PIC - a company I worked for used to be a member of PIC, we installed both Electro plating units and wire wool systems. With steel or wire wool systems the resulting slugde isn't very pure usually often about 60% silver, whereas plated silver will be over 98% pure, often far higher.

Ian

Thanks for that idea. I didn't realize it might be so simple to separate out the silver. I have a couple of basic questions about the plating process...

I presume any direct current source with several volts will work same as the battery?

After plating out the available silver, what do you do with whatever liquids and sludges that remain?

How disposable and safe is that remainder?

How do you know when you've got the plating job done?

How often does one do the plating job?

Are there any other basics one should know?

Thanks!

C

 

[Ulrich Drolshagen]

Thanks for that idea. I didn't realize it might be so simple to separate out the silver.

Before trying this method I suggest you to talk to someone who knows his ropes. Otherwise you might blow up your home with oxyhydrogen gas, produce some nasty chemicals or something else like that. AFAIK for seperating silver electrolytically you will have to thoroughly control the currence and voltage.

Ulrich

 

[Fulvio]

I'm curious, are interested in silver recovery because you think it's an environmental hazard, or do you intend to sell-back the silver for cash?

If it's to save the environment, that concern was nearly beaten to death a few months ago on this forum. I'll offer no further comment in that regard.

in these days I was doing some electrolysis experiment (no photography related) and then I thought of some use for recovering silver... I'm no chemist, that's why I asked on APUG first: if there was a reliable system - I thought - some other must already be using it.

Running an electrolysis process costs time and money. I don't know if the quantity of silver one can recover from a fixing bath is worth the effort.

If making silver nitrate wouldn't be such a deadly task, I would be tempted to claim the metallic silver and make my own silver nitrate which I use extensively in my photography and printmaking. But that is definitively NOT a thing I will ever attempt to do.

Is there a similar way to restore the fixing bath? Ok, the fixer doesn't cost as much as silver does, but I wouldn't totally disregard the idea of having my fixer life extended a little bit. I'm into wet plate photography now and I'm consuming a lot of hypo. It's not expensive, but you need a lot of it and dies quickly.

 

[dancqu]

Is there a "cheap" way to recover metallic silver
from the fixing bath?

...deadly insane as making silver nitrate!

The FT-1 hypo check uses potassium iodide to
precipitate silver iodide. In excess it will clear a
hypo of nearly every last trace of silver. Same
for sodium sulfide. Both salts form extremely
insoluble salts with silver; the sulfide being
the least.

Fixer loads up with chloride, bromide, and iodide;
the remains of the silver salts which make up a
silver gelatin emulsion. Also, old fixer is likely
quite oxidized. Addition of sodium sulfite
after electrolytic extraction of the silver
may extend it's life some.

BTW, silver nitrate is safe; the component in the
FT-2 test and used in emulsion making. Dan

 

[Photo Engineer]

Electrolytic recovery is normal in much of the industry, but AFAIK it destroys the fix. I have forgotten over all the years since I worked on this. Ulrich is right though, it must be carefully controlled to prevent evolution of unwanted gases.

Saw Dan's post after this went up. He is totally correct. KI added to the fix will precipitate out most all silver salts and complexes as Silver Iodide.

PE

 

[CBG]

Electrolytic recovery is normal in much of the industry, but AFAIK it destroys the fix. I have forgotten over all the years since I worked on this. Ulrich is right though, it must be carefully controlled to prevent evolution of unwanted gases.

Saw Dan's post after this went up. He is totally correct. KI added to the fix will precipitate out most all silver salts and complexes as Silver Iodide.

PE

Sounds like it isn't so simple after all. Oh well. I had assumed the fix would be dead after silver recovery. Didn't plan on hearing about evolving oxygen and hydrogen.

Thanks,

C

 

[Ian Grant]

Electrolytic recovery is simple and effective, in practice under some circumstances the fixer can be re-used and it isn't harmed at all by the process, but the build up of iodide from film emulsions limits the reuse. If the plating is done at too high an ampage then yes sulphurisation takes place, commercial electrolytic recovery units have circuitry to control the voltage & ampage to prevent this.

Some re-circulating units recover the silver electrolytically from Fixer or Bleach Fix on continuous process machines, allowing slightly more efficient use if the chemistry, however the sophistication of the control circuitry is far higher than for standard plating units, because as Ron (PE) says fixers and particularly bleach fix can be damaged, these units control the voltage and ampage to give a slower rate of recovery.

On an industrial scale spent fixer or bleach-fix is desilvered electrolytically and often used again and again to recover silver from old X-ray & Graphic Arts films. So often when fix solutions are sent for recycling they get used again before final treatment & disposal.

To have a any problem with Hydrogen & Oxygen liberation you would need a very large commercial rectifier to generate the high ampage required, commercial units are designed to cut out well before that point can be reached, as by then the plating process would have broken down anyway.

Small scale recovery from a litre or two of fix using a battery system would be very safe and easy, I would only advocate using a purpose built mains unit. The secret to good plating is to keep the ampage low and allow the silver to plate out slowly, there's plenty written about plating on other websites.

Ian

 

[snallan]

The electrochemical potential for the reduction of silver ion to silver is around 0.8V. So if you were to use a battery, or wall-wart style DC source, it would be best to arrange a series of cells in series to regulate the voltage in each. If you cannot get hold of silver wire, or sheet, to form the anode, you could use stainless steel (ie. any old unused stainless steel knife blades) in its place. If I remember correctly, silver plated on to stainless steel does not form a very strong bond, and can be removed by flexing the blade, or scraping off.

The gasses evolved using too high a voltage or amperage will contain dissociation products of the thiosulphate anion, which will be hydrogen sulphide - smelly, poisonous, and dangerous to unexposed photographic emulsions. Indeed this will probably take place in preference to the dissociation of water to form hydrogen and oxygen (though I would have to drag out the Rubber Handbook, and brush up on my electrochemistry to prove that one way or the other).

 

[Photo Engineer]

Steve, Ian;

It has been too long. Now you are refreshing my memory. You have to control the voltage precisely to get silver without harming the fix, otherwise overvoltage causes the hypo to decompose. Also, with acidic fixes, the fix is probably going bad anyhow from oxidation by the time it is so well used that there is enough silver to warrant reclamation.

This is why I seem to remember that it is suggested that the fix be discarded after the silver is reclaimed.

PE

 

[CBG]

Could anyone specify what levels of voltage are safe for not gassing out bad things. I do not seek to reuse fix. My interests are, first to make the spent fix safely disposable, and second, to not waste silver.

Thanks,

C

 

[dancqu]

I do not seek to reuse fix. My interests are,
first to make the spent fix safely disposable,
and second, to not waste silver.Thanks,

Well that's another matter. I suggest this method
ONLY for sodium thiosulfate fixers. I conducted an
experiment using H2O2, hydrogen peroxide, to
destroy the fixer and so release the silver.
At the time I had been using potassium
iodide as per Kodak's FT-1 test for
testing the fixer's condition.

All went as expected. The silver precipitated
as a brown-ish flocculant. Likely the oxide or
hydroxide of silver. Add acetic acid to that
and you've silver acetate. Dan

 

[Mr Bill]

There was a guy on photo.net who seemed to know something about it. It seems like he told about everything you need to know, except how to build a power supply and how to know how silver is there to begin with.

http://photo.net/bboard/q-and-a-fetch-msg?msg_id=007Nxn

If that guy were here right now, I'm sure he would agree with Ian that a rechargeable battery would be a good way to go for the hobbyists. Safe with reliable voltage control.

There is a tendency for pH to go down somewhat during desilvering, so if you use a hardening fixer with a fairly low pH (acidic), it's possible you might get precipitates forming. Probably safer to raise the pH a bit (perhaps to about pH => 6 ?), but I don't have any experience with such fixers (so I'm just guessing).

Aside from the loss of sulfite and pH shift, the fixer should not be harmed. Of course, if you want to, you CAN harm it with excess voltage. At any rate, it's generally not worth the trouble to reuse fixer. Disclaimer: not a chemist, electrical engineer, etc, just a guy who has some experience recovering silver.

 

[Douglas]

I am seeking an easy, inexpensive way to recover silver from photographic processing solutions. I am particularly interested in a refiner/smelter who offers a vault storage account for reclaimed silver, if such a service exisits.
Any thoughts at all would be welcome. Thanks.

 

[Ulrich Drolshagen]

This topic comes up once in a while. Try the search function. There will show up threads like
(there was a url link here which no longer exists) for example.

Ulrich

 

[removed account4]

hi douglas

get yourself 2 or 3 iron core trickle tanks
run them in series, spent fixer as well as wash.
it will transfer iron ions for silver.
let your fingers do the walking through the yellow pages
look under electroplaters/refiners or waste haulers, and you will be
speak to a refiner who will supply you with the tanks, and to find out the best way
to see when the first is FULL, then trade it in, buy a new one
for the end, run them in series again and again.
don't get the other trickle tanks ( the ones that aren't iron core )
if they are not run continuously and are not wet all the time
they channel and don't work and are a waste.

good luck!
john

 

[Douglas]

My thanks to those who have replied to my request. I will pursue accordingly.

 

[David A. Goldfarb]

Five threads merged. Since the question of how to recover silver from exhausted fixer, or at least how not to dump it into the waste stream, comes up with some regularity, I'm adding this to our sticky threads.

 

[Ian Grant]

These merged sticky threads are a bit of an mess really. It might be better to have an article on Silver Recovery for small scale users. This would be quite short and reasonably simple, it's an area I specialised for a bullion dealers n for a number of years.

Ian

 

[David A. Goldfarb]

It would be great to have such an article, and I encourage you to write it, if you are interested, but meanwhile we have a lot of dispersed threads that users don't seem willing or able to look for, so they start new ones on the same topic, and then this makes more redundant threads and scattered information, so we're doing what we can with the resources we have to try to focus these discussions.

We've talked about an FAQ, but for whatever reason, information structures on APUG that are ancillary to the main forums don't get that much traffic, and it's a lot of work to put together an FAQ, particularly if it isn't likely to be used. People come to internet forums to have discussions, so the object is to try to organize the information in a way that users seem to want it.

 

[Ian Grant]

There's nothing worse than each Forum being filled with Sticky threads, and currently there are far too many as it is. I will write the Silver Recovery article but it will be a month or so before I'll get time.

Ian

 

[David A. Goldfarb]

Thanks for offering to write the article. I'll be looking forward to it, and I'm sure others will as well.

Right now there are three sticky threads in this forum (B&W: Film, Paper, Chemistry), which is the largest forum on APUG. We haven't really created that many of them, and we're trying to be careful about creating new ones. We have been merging some redundant threads, but we don't make all of them sticky. If there get to be too many (like a whole page of stickies at the top of one forum), we'll think about how to fix that, but at the moment, that doesn't seem like it will happen in the very near future. It will probably make sense at some point to split up "B&W: Film, Paper, Chemistry" into two forums (B&W Film and Processing, B&W Printing Papers and Chemistry, or something along those lines), but for now, Sean's got other things to work on.

 

[David A. Goldfarb]

While we're on the subject--for those who use the method of pouring spent fixer into a jug or a vat with steel wool--do any of you folks actually have someplace that will buy the sludge and recycle the silver from it? If so, where do you send it? I realize that silver recovery companies have systems with cartridges and such for larger labs, but does anyone have a name of a company that takes silver waste in the form you would get from homebrew silver recovery? I realize that it might take a while to amass enough sludge in a home darkroom to make it worth recycling, but say I wanted to save it up and do it every couple of years. Where would I go?

No Google answers, please. I want to know who really does it and what their experience has been with companies that will actually take this stuff in small quantities.

 

[richard ide]

I contacted Imperial Smelting in Markham Ontario a few years ago. I asked them about silver from an electolytic recovery unit. After paying assay charges etc., it would only be economical for quantities with a value of about $1000. IIRC.

 

[jerry lebens]

Hi David,

Picked up this thread late - as usual. I used these trickle systems (http://www.photomart.co.uk/ProductDetail.asp?ProductID=31261) when I ran a hand printing lab, I found them v effective. They deliver the system, you use it for about a year and they come back and replace the bottom bucket. They keep the revenue from the silver recovery but it leaves you with a clear conscience - that you aren't throwing silver salts down the drain. £60 per year didn't seem a bad price to pay.

I was told by Photomart that they were imported from the US.

Regards
Jerry Lebens

 

[efranqueville]

Hi there, I m new to this forum, but I ve red this thread with some attention, and you don't talk about recovering silver using piece or powder of copper.
Is it possible that after precipating the silver on the copper , filtering it and put everything (part of the filter also) in nitric acid it should remains some Copper and Silver Nitrate, and put appart those two thing almost easily (I know how to do this actually but never done it ), and then cristalise the silver nitrate to re-use it .

I m doing wetplate and albumen print and I can get a lot of old fixer (I took 10liter just to try during holiday) , with tetenal fixer test strip I can read that they contains almost 7gr/L of silver, so maybe it worth it ?