Need help with silver recovery from x ray films

[Fredtaa]

Hey, Guys.

I have been extracting silver from x ray films using 10% naoh solution, heated to 80°C.

The next day, when all has setteled, i decant the solution leaving me with the silver sludge.

This is where the problem starts. I know when using naoh, the gelatine is left behind as well, so you have to roast off the gelatine, leaving only silver oxide.

Whenever i do this, it all kind of melts in to a sticky brown goo.. it also smells horrendous. I keep the temp at 400°C give or take for approx 30 mins.

If i proceed in melting this product with a blow torch, i end up with a black liquid with a bit of silver beads at the bottom. Its so much of the black stuff that its hard to melt the silver. This stuff boils long before the silver melts.

I have tried to mix it with 50-50 soda ash, and 50-50 borax, without any changes in the final product.

When the goo is cold, its hard as a rock, but its possible to dissolve this goo in water, leaving the water with a black/green tint.

Does anyone know what this goo could be? Any solution in getting rid of it?

Any help would be highly appreciated.

Best regards, Fredrik.

 

[Lino1406]

Silver content 1% complies with the beads you formed?

 

[Yggdrasil]

I tried to reply, but it disappeared for some reason.
Try higer tempereature until it stops fuming/smoking and get slightly red.
Make sure it has sufficient access to oxygen, so the carbon ash forms carbon dioxide.

 

[Fredtaa]

Ok, i will try with a higher temprature. But is it supposed to be fluid like that? Could it be exess naoh that needs to be washed out?

Would it make any difference if i neutrulized the silver/gelatine sludge with some acid for instance? Just to bring the PH down to 7..

Lino 1406
Im not sure to be honest. I used 150 sheets of 4x8 inch films.
My yield came out to 14.7 grams of silver.

 

[Yggdrasil]

Of course, if there is too much NaOH it will lead to all kinds of strange behaviour.

Try to neutralize with HCl and clean it several times
with water. Still, since your solution was 10 percent
it seems a bit odd, if you have that much excess NaOH.

Regards Per-Ove

 

[1mysurveymail]

I am running a batch like yours. The first attempt at incineration just seems to have gotten the film to melt. I DID use borax and washing soda as a "flux" This first burn was just at "fire pit" temps, so I did not expect much.

Then I hit the goo with just a propane air torch. I could see small beads of silver coagulating... The next go around, I plan to add more borax, but would like feedback as to whether or not washing soda contributes Oxygen enough to rationalize putting more in. Or is oxy/acetylene necessary to contribute enough oxygen to warrant breaking out my other torch?

I have a lot of oak and pallets to stoke the fire with, but I am doing the (mix) of keyboard mylars and dry X-ray films in a 3 gallon enameled pot. So the only oxygen entering is from the open top. Time will tell if just an oak fueled fire will be enough to carbonize the films and mylars. Hopefully the Borax will help let the shiny bits fall to the bottom.

Hopefully, Temperature, flux and gravity should allow the molten droplets to congeal. I don't expect much yield from the 10lbs of modern "dry" X-Rays, and 10lbs of keyboard mylars, but who cares? It gives me another excuse to light a bonfire, and see what slumps out.

More later.

 

[Lino1406]

According to your information, 14.7 g is what expected. The rest black liquid can bring a small addition if you give it a long time to settle