silver from unprocessed photo papers

[Rick Miller]

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.

 

[ION 47]

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.

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?

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.

 

[ION 47]

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.

 

[ION 47]

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

 

[ION 47]

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

 

[ION 47]

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.

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.

 

[ION 47]

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.

 

[rickbb]

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.

 

[Platdigger]

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."

 

[ION 47]

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.

 

[Rick Miller]

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!

 

[Rick Miller]

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!