# silver from unprocessed photo papers



## Rick Miller (Jun 24, 2018)

I've been haunting as a guest for some time. this is my first post. Acquired 7 pallets of unprocessed photo papers that were expired back in 2001. Have read about the different ways of retrieving silver from this and decided to go with incineration, followed by smelting of the ashes. I realize i'm losing quite a bit from open burn, just didn't know how else to handle this stuff. I"m not trying to make money on this, just fun to tinker on. After several runs I've collected about 11 tr oz. of silver. So my question is this, Is there a way to concentrate the silver present in the ashes farther, before i go to the crucible and fire it? Also, what state would the silver be in after burning the film? Still AgCl or would it be an oxide? Thanks for your time. really hooked on this site, so much to learn.


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## Lino1406 (Jun 24, 2018)

You can spare the not friendly (ecologically) incineration by rinsing the foils, one by one in caustic soda 20%. For that build a simple mechanism, a revolving thread of which the foils are suspended.


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## Rick Miller (Jun 25, 2018)

Thanks for the input, I have considered stripping with caustic. Even so far as drawing up ideas for an automatic unroller. After learning that 25 to 30 percent is lost in burning, may lean this way.


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## anachronism (Jun 25, 2018)

Rick Miller said:


> After learning that 25 to 30 percent is lost in burning, *may* lean this way.



May?


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## goldsilverpro (Jun 25, 2018)

Rick Miller said:


> Thanks for the input, I have considered stripping with caustic. Even so far as drawing up ideas for an automatic unroller. After learning that 25 to 30 percent is lost in burning, may lean this way.



Of course, you don't want to use a solution strong enough and/or hot enough that will pulp the paper and create a big mess, which 20% caustic might do. In large scale production (10,000 pounds per load), we only used a 3-4% NaOH solution for film, but it ran at 200F for an hour. In my last refinery, I ran 10% caustic on film, in a tumbler, at about 140F for about 15 min. You might be a able to shred the paper in a fairly heavy duty paper shredder, which might also do the unrolling for you. That could solve the horrible thought of spending several years running one piece at a time. You could probably tumble shredded paper, in a solution, in a small portable plastic cement mixer, in batches. Another way is to use a small bucket, with holes in it, inside of a larger bucket containing the solution. The shredded paper is put into the smaller bucket and bobbed up and down, gently, ever so often.

I spent several years in a plant that ran a million pounds of film per month, but we NEVER ran paper. We (and, everybody else) sent the paper we got out for incineration. If I were to use chemicals, with paper, I would want to dissolve the silver halide, which NaOH won't do. NaOH attacks the emulsion and the silver, as an oxide, falls off with the emulsion, which is sort of like a gelatin. Sodium thiosulfate (photo hypo or fixer) is the only safe chemical which will dissolve the silver halide without removing the emulsion (the only other two possibilities are cyanide or ammonia). If you search for refining photo fixer on the forum, there should be a lot of info on how to recover the silver from the hypo. I always used an electrolytic cell, but the special type needed is quite expensive.

I foresee a TON of very small, lab-size experiments in your future. I would try anything and everything, including the caustic. By the way, what kind of paper is it. If it's for photos, whether color or B&W, it could run pretty good in Ag. If it's like old FAX paper, not nearly so good. If you know the manufacturer, and what it's used for, you might be able to find out the silver content, usually given in grams of silver per sq. meter, I think. I know Kodak used to publish that info for their products.

Another possibility. For about a year, I tumbled and stripped the emulsion/silver from film using a proprietary enzyme (protease type, I think). The solution contained about 45 to 60 grams/liter of baking soda (gave a pH of about 8.5, if I remember right) and about 110-120F. The tank was about 250-300 gallons and, every morning, I added only 400 ml of the high dollar liquid enzyme, which lasted all day and worked great. Very safe solution. The only problem was that it smelled like an outhouse. I've always been curious as whether a septic tank enzyme, like Rid-X, might work. Worth a small test in about a 250 ml beaker. 

Were it mine, I would probably play with it for awhile and end up burning it. 

Where in SW MO? My home town is Nevada, MO. I just moved to Arkansas from there couple of years ago.

Good luck!


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## Rick Miller (Jun 26, 2018)

I live in Aurora. About halfway between Springfield and Joplin. You have given me much food for thought. If I remember true, weak NaOh will strip everything from the paper. The silver oxides are then smelted. This seems to me to be the simplest approach.


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## anachronism (Jun 26, 2018)

Chris I look at 25-30% loss and panic 8) 8)


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## Rick Miller (Jun 26, 2018)

Knew I was losing some, didn't know it was anywhere near that much


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## goldsilverpro (Jun 27, 2018)

anachronism said:


> Chris I look at 25-30% loss and panic 8) 8)


Those numbers are from an old Kodak booklet discussing open burning of FILM. Paper might be worse.


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## goldsilverpro (Jun 27, 2018)

Rick Miller said:


> I live in Aurora. About halfway between Springfield and Joplin. You have given me much food for thought. If I remember true, weak NaOh will strip everything from the paper. The silver oxides are then smelted. This seems to me to be the simplest approach.


Aurora and Nevada were in the same athletic conference when I was in high school - called Big 8. 

The problem I foresee with NaOH is the mechanical separation of the emulsion/silver from the paper, after stripping.


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## Rick Miller (Jun 27, 2018)

Read that the resulting sludge was decanted, then baked to carbonize the gelatin. Then go to smelter or electric cell. Did I miss aomething?


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## goldsilverpro (Jun 27, 2018)

Rick Miller said:


> Read that the resulting sludge was decanted, then baked to carbonize the gelatin. Then go to smelter or electric cell. Did I miss aomething?


Was that from film or paper? I haven't run paper, but, when using caustic soda, I would guess it's harder to separate the sludge than it is with film. I first leached the film sludge with 20% sulfuric (or battery acid diluted 50/50). Then I filtered and rinsed it well. That made it easier to filter and reduced the sludge volume quite a bit. Then, I obtained a 24" discus blade (shaped like a wok) from a scrapyard and welded the center hole closed. Then, I put it on top of a few bricks on my gas furnace and burned the sludge slowly, with occasional gentle stirring, until all the black (carbon) was gone and the sludge was light gray in color. For smaller amounts, you could use a carbon steel wok over a gas camping stove - just make sure the acid is rinsed out or use a weak NaOH solution for the last rinse, or you will eat holes in the wok. When the sludge burns it really stinks. Then I flux melted it with borax. I also added some soda ash, in case there was still a little silver halide unconverted. The silver used in photo material is about 99.99% pure to start with and, unless you contaminate it with another metal, there should be no need to run it through a cell.


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## Rick Miller (Jun 28, 2018)

Hope I'm not being bothersome. Dipped samples into 10% NaOh. The bluish-gray color immediately goes away. Could it be the Ag bearing emulsion is that 'loose' for lack of a better word? GSP, you mention hot solutions and extended exposures for film.


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## goldsilverpro (Jun 29, 2018)

Rick Miller said:


> Hope I'm not being bothersome. Dipped samples into 10% NaOh. The bluish-gray color immediately goes away. Could it be the Ag bearing emulsion is that 'loose' for lack of a better word? GSP, you mention hot solutions and extended exposures for film.



Don't worry about being bothersome. It's rare that I find a topic that hasn't already been discussed 1000 times and rarer still that it's one I'm interested in enough to answer. If I didn't want to answer, I wouldn't.

I've never run paper and have no idea what it should look like, before and after, and I've never seen any with a blue-gray color.. The NaOH working immediately is suspicious. With most any chemical reaction, heat will speed it up and that's about the only reason for doing it on film. If you can avoid heating, you're much better off, The main variable here is the emulsion, which is probably different than that on film. The emulsion on film is a gelatin, made up of amino acids. It breaks down and falls off the plastic with NaOH. With paper, who knows?

Your biggest problem, it seems, is to know whether or not you've removed all the silver. You could have just removed some sort of blue-gray coating. With film, you end up with a clear piece of plastic. If you can obtain a little B&W photo developer online, probably on eBay, you could probably dissolve some in water and use it to test for residual silver on the paper - developer should turn it dark if silver were still present. Most developers have metol and/or hydroquinone, strong reducers, in them, which turn silver halide to silver metal, which is black when finely divided. You might try coffee, wine, or Tylenol and a developer, as in this link. However, with paper, there would be severe staining with coffee or wine and that would mask the test. Maybe the Tylenol. Try it first on an untreated piece, so you'll know what it looks like.There are probably other things you could find on the internet.
https://digital-photography.wonderhowto.com/how-to/diy-photo-processing-develop-film-home-for-cheap-using-coffee-red-wine-tylenol-0150465/

What color is the NaOH after stripping? If you actually stripped some silver/emulsion, you will see fairly dark solids in the solution, in good lighting, since they won't dissolve in NaOH. What happens, mainly colorwise, if you leave the paper in the solution for, say, 30 minutes of even longer?

If the paper is used for color prints, it contains dyes, and that could be a whole different kettle of fish. That could be where the blue-gray color comes from.

Most of what I said in this post is just thinking out loud guesswork.


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## Rick Miller (Jun 29, 2018)

I like it when you think out loud. Still sampling


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## goldsilverpro (Jul 1, 2018)

Rick Miller said:


> I like it when you think out loud. Still sampling


Keep us posted on what you've tried and the results.


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## ION 47 (Jul 2, 2018)

Rick Miller said:


> I like it when you think out loud. Still sampling


Rick, good day! I process the x-ray film is not exposed, as well as the photo paper by the following method: I grind the material to a size of 2 cm by 2 cm, load the wicker bags, and fill (1 cubic meter) solution of sodium thiosulfate. The thiosulfate solution is taken from the bottom of the barrel and pumped through the electrolysis cell, then fall back into the barrel. And so on until there is no silver in the solution. Thiosulfate solution can be used repeatedly. Modes and techniques can be used in the series "J" from Kodak. I think you'll lose a lot less silver than by burning the photo paper. With respect, Yevgeny.


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## goldsilverpro (Jul 3, 2018)

ION 47 said:


> Rick Miller said:
> 
> 
> > I like it when you think out loud. Still sampling
> ...



That could work great, assuming there enough agitation of, or on, the cathode to reduce the formation of the black silver sulfide.

Does your electrolytic unit have a rotating cathode? If not, how do you do it?


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## Rick Miller (Jul 3, 2018)

Yevgeny, thanks for the input. I have ordered ammonium thiosulfate to run a sample with. From my reading, it sounded better than sodium thiosulfate. What are your thoughts on the difference between the two? Also, my paper is in large rolls. I'm attempting to unroll it through a bath. I haven't had this much fun in a while.


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## goldsilverpro (Jul 3, 2018)

Rick Miller said:


> Yevgeny, thanks for the input. I have ordered ammonium thiosulfate to run a sample with. From my reading, it sounded better than sodium thiosulfate. What are your thoughts on the difference between the two? Also, my paper is in large rolls. I'm attempting to unroll it through a bath. I haven't had this much fun in a while.



Like i said before, it's success is based on cathode agitation. All of the many electrolytic systems that were once sold for this purpose had a rotating drum cathode, made of stainless steel. This would give a constant exchange providing fresh solution to the layer right next to the cathode metal, the cathode film. Without sufficient cathode film replacement, the thiosulfate will decompose and deposit a layer of sodium sulfide + a little silver sulfide, a stinking black slimy substance which falls off the cathode. That's why I asked *Yevgeny* what he was doing about the cathode situation. Maybe he has a trick up his sleeve. I am still interested in that. He probably is using a commercial unit with a rotating cathode, though. The number of amps you use could also be critical.

To make this work, you must do something about the cathode. Although I've never tried it, a flat sheet of stainless could be used for the cathode (and anode), and the output from a pump set to impinge directly on the cathode face. This might provide enough cathode agitation to prevent the sulfide formation. Even with the very best agitation, some silver sulfide will form and the silver will never be pure. I've seen it vary from about 80% (black stinking slime) to about 99% (hard white brittle metal). Any metal adhering to the cathode is brittle and can be removed by flexing the stainless sheet a bit. 

In any case, the silver can be purified easily by melting it with about 1/3 to 1/2 it's volume of a flux mixture consisting of 3/4 anhydrous (preferably) borax and 1/4 soda ash. Several lengths of rebar long enough to protrude out of the crucible, so they can be easily removed, are added. some of the iron from the rebar combines with the sulfide and it becomes part of the slag. After 30, or so minutes, the rebar is removed, the melt poured into a cast iron mold, When everything becomes solid, the bar is dumped and immediately quenched, while still hot, in a trough of cool water. What slag remains is chipped off. Pure silver bar.


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## Rick Miller (Jul 3, 2018)

GSP, maybe I didn't elaborate enough. I was just curious about the difference between ammonium thiosulfate and sodium thiosulfate in the pulling of silver from the paper.


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## ION 47 (Jul 3, 2018)

goldsilverpro said:


> ION 47 said:
> 
> 
> > Rick Miller said:
> ...


My equipment consists of a large barrel (1 cubic meter), a pump of 1500 liters per hour (the performance can be controlled by a frequency regulator), a electrolyser with two rotating (150 revolutions per minute) stainless steel cathodes with a total active surface of 1 square meter, anodes made of graphite plates, a power supply unit that operates on a three-electrode circuit in potentiostatic mode. The maximum cathode current is 100 amps per 1 square meter, the current is set automatically depending on the silver content. I typed on cathodes up to 8 kg of silver (4 for each cathode). Oh, I forgot: the Cathodes rotating in a bath of 100 liters. This is my electrolytic cell. pump from the barrel 1000 liters in the bath to the cathode, from the bath by gravity to the eurocub (barrel) with bags of film or photo paper. Activation is due to the supply of fresh pump solution and due to the rotation of the cathodes. The sludge on the cathodes contains 98.5 % silver.


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## ION 47 (Jul 3, 2018)

Rick Miller said:


> GSP, maybe I didn't elaborate enough. I was just curious about the difference between ammonium thiosulfate and sodium thiosulfate in the pulling of silver from the paper.


Ammonium thiosulfate works faster than sodium thiosulfate, it is used to speed up the process of fixing photo prints (usually mixed with sodium thiosulfate) in developing machines. The ammonium thiosulfate will work, but with the correct electrolysis mode, the hydrogen pH will grow, it will smell like ammonia, ventilation is needed.


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## ION 47 (Jul 3, 2018)

the cell can be made with the activation of the pump, the cathode in the form of a stainless steel pipe, the anode of the coal rod in the center, install all this in the housing of the household flow water filter, seal the holes into which the wires are passed for the supply of electricity. to give a voltage 1,5- 2 volts. Such devices were made in Canada. The supply of fresh solution at the cathode should be uniform, so that there are no stagnant zones of the solution. Otherwise there will be a blackening of silver


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## ION 47 (Jul 3, 2018)

Rick Miller said:


> Yevgeny, thanks for the input.... Also, my paper is in large rolls. I'm attempting to unroll it through a bath. I haven't had this much fun in a while.


Paper you need to chop, you can use like this: Rayson Shredder A506P, the density will be greater. You should try to pour as much paper to the silver content in the solution was 2-5 grams per liter


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## ION 47 (Jul 3, 2018)

goldsilverpro said:


> Rick Miller said:
> 
> 
> > Yevgeny, thanks for the input. I have ordered ammonium thiosulfate to run a sample with. From my reading, it sounded better than sodium thiosulfate. What are your thoughts on the difference between the two? Also, my paper is in large rolls. I'm attempting to unroll it through a bath. I haven't had this much fun in a while.
> ...


I also use an Autonomous electrochemical AK-1 ( informationit available on the Internet), the cathode of which consists of a conductive porous material, the activation of the solution in it is due to the supply of a solution of 1000 liters per hour in the interelectrode space.


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## ION 47 (Jul 3, 2018)

Rick Miller said:


> Thanks for the input, I have considered stripping with caustic. Even so far as drawing up ideas for an automatic unroller. After learning that 25 to 30 percent is lost in burning, may lean this way.


Rick, one more recommendation: do not keep photo paper under the influence of sunlight for a long time, ultraviolet light restores silver from salt, and thiosulfate will not be able to bind the complex with it, there will be losses, it will be necessary to use a bleaching solution, which is much more difficult.


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## rickbb (Jul 5, 2018)

You should be able to find an old, still working film processer from a printing company. Along with that a electrolytic recovery unit.

Run the paper through them, recovery almost pure silver, with very low losses, then re-sell the equipment for what you paid for it. 

It's what I would do with 7 pallets of unprocessed photo paper.


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## Platdigger (Jul 5, 2018)

For whatever reasons they claim:
"The AK-1 complex does not admit the cathode decomposition of thiosulfate and creates the conditions for repeated use of the fixing solutions in the photographic process."


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## ION 47 (Jul 5, 2018)

Platdigger said:


> For whatever reasons they claim:
> "The AK-1 complex does not admit the cathode decomposition of thiosulfate and creates the conditions for repeated use of the fixing solutions in the photographic process."


https://waste.ua/cooperation/2008/theses/vays.html The authors here point out that this equipment allows to maximalle preserve the components of the process solutions of photo printing. Operation of AK-1 in my shop showed: decomposition of thiosulfate is certainly present, but very small. The electrolysis current is set automatically depending on the set potential and the silver content in the solution. The greater the current density, the worse the thiosulfate is preserved, sulfur begins to sit on the anode, and sulfide on the cathode. I have now switched to using equipment with rotating cylindrical stainless steel cathodes. Each equipment has positive and negative properties.


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## Rick Miller (Aug 7, 2018)

Ok, I've tried unrolling the material through NaOh at various strengths. Also with bleach. Apparently I'm not enough of an engineer to make it an automatic process. Onwards with the incineration. Back to my original question, would there be a way to concentrate the silver content found in the ash? Maybe a wash or gravity separation? Thanks so much for the continued patience with this old hillbilly!


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## Rick Miller (Aug 22, 2018)

I have been reading on gravity separation. Believe it may work, just afraid of losing more silver. I will experiment using a recirculating system just in case. Still not clear what state the silver is in after initial burn. If it is anything but elemental, I can see where gravity may not work. Blundering along, but having fun!


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