How to recover silver from bleach fix?

[Anonymous]

hello everyone.
Does anyone know how to recover silver from spent bleach fix (chemical for color photography). I've try electrolysis but no success. I made the device my-self and it work just fine with spent fixer but doesn't work on bleach fix. Already try adding some sodium hydroxide to make the liquid more basic (like in kodak literature) but still haven't got any silver yet.

And one more thing, why can't a silver estimating paper for fixer be used to test silver content from bleach fix? my silver estimating paper seems to not work on bleach fix. (i use johnson silver estimating paper)

thanks.

 

[ILikeBoats]

I don't think there is very much silver used in C-41 process (print) or E-6 process (color slide like Ektachrome) used. It is primarily a dye-based process.

Only K-14 (Kodachrome) and black and white processes use silver halide in any quantity.

See here:

http://en.wikipedia.org/wiki/C-41_process

Could it be that other chemicals in the mix are interfering with your process? Perhaps dust and other junk have just made your setup too contaminated?

 

[Juan Manuel Arcos Frank]

Santolim:

You can recover the silver from spent bleach/fix,but using an electrolytical cell you have to rise current to 25 amperes,if you do not do that you will never get the silver.

To measure the silver content I have posted how to do it using a simple copper wire...the silver content in BFX is 1.5 to 2 grams/lt.Keep me updated about your progress.

Regards

Manuel

 

[Anonymous]

Santolim:

You can recover the silver from spent bleach/fix,but using an electrolytical cell you have to rise current to 25 amperes,if you do not do that you will never get the silver.

To measure the silver content I have posted how to do it using a simple copper wire...the silver content in BFX is 1.5 to 2 grams/lt.Keep me updated about your progress.

Regards

Manuel

thanks everyone.

Juan, do i need 25amp current for any elactrode or the surface of the electrode matter too? I've read some literature that says if i have a small electrode then lower current should works just fine. (the current needed is in Amp/surface area of the electrode).

Whe can i find the post about using simple copper wire to test for silver? is it done by simply dipping the wire in the solution? well, if so, then may be my solution contain too little silver because simple copper wire dip doesn't shows any silver at all (the copper doesn't became silvery).

My solution is actually a mix of chemical from negative color film processing and from photographic paper processing. The guy who gave it to me says that it was chemical from the third process in negative film and second process from paper. Being new to this field i just think that it must be bleach fix, because the guy who gave it to me says it contain silver and there are people collecting it for silver recovery.

ps:
how many silver there are in fixer?
my DIY recovery unit gave me about 7grams/lt (fixer from x-ray processing) and 15 grams/lt (fixer from printing press), does copper wire dip really a good test to see if there is any silver left, can the PH of the solution influence the process and making copper wire can't detect the silver?

many many thanks
-santo

 

[Juan Manuel Arcos Frank]

Santo:

When the the bleach/fix is mxed with the film fix it becomes a nightmare...bleach/fix contains iron and competes with silver in your electrolytic cell..that is why current must be 25 A. in the (-) electrode.To process just film fixer you just need 10 A or lower.

My silver check process with a copper wire is right here,in the index "SILVER" see "Method for recovering silver from photochemicals"...there is a table with times/concentration relationships.Check your silver concentration,common bleach/fix is 1.5 gr/lt,film fix could be 6-12 gr/lt.

pH is very important in the recovery process....must be acid (4-5) for film fix and basic (7-8) for bleach/fix...that is why yuou have to add NaOH to bleach/fix.Copper wire is the best qualitative method to check silver contents in photo chemicals.By the way,Have you read the "J Series" from Eastman Kodak?...in the post mentioned there is a file with all of them.

Keep me updated about your progress.

Have a nice day

Manuel

 

[goldsilverpro]

Santolim said:

Juan, do i need 25amp current for any electrode or the surface of the electrode matter too? I've read some literature that says if i have a small electrode then lower current should works just fine. (the current needed is in Amp/surface area of the electrode).

Juan said:

When the the bleach/fix is mxed with the film fix it becomes a nightmare...bleach/fix contains iron and competes with silver in your electrolytic cell..that is why current must be 25 A.

Santolim has a very valid point. Do you need 25 amps, no matter what the size the cathode is? I would say no. If the surface area of the cathode is 1 square mile or, if it is 1 square inch, do you still use 25 amps in both cases? Absurd. Every electrolytic system on earth is based on setting the amperage based on amps/square foot, or square inches, or square decimeters, or square whatever, of the area of the cathode. This is called current density, in the trade. Maybe, Juan, your particular cathode surface area (probably a cylindrical, rotating stainless steel drum) requires 25 amps for the proper deposition on silver. For a cathode of half the surface area, however, it would only require 12.5 amps. It's always proportional.

What is the surface area of your cathode that requires 25 amps? We can go from there.

Concerning the copper wire test for silver content in fixer. In the 1000s of times I have used this test, over the last 30 years, I found that, for repeatability, the copper wire must be well cleaned before testing. I usually scrap the wire with a knife or with sandpaper.

It is much more accurate to test the silver content of the fixer with Kodak estimating papers. If you don't want to spend the money, you can make your own by soaking (and then drying) strips of filter paper in a solution of sodium sulfide.

 

[Lino1406]

The silver content may be too low
for profitability, a solid caustic
flake should blacken in the fixer.
Did you try that?

 

[Juan Manuel Arcos Frank]

GSP,my dear friend:

Yeah...you are right about current density..I was speaking just about my SRU,by the way its cathode´s area is 1105.8 cm2 (1.188 ft2) so I need 21 A/ft2 for bleach fix and 8.4 A/ft2 for fix.

Wonderful idea about making the yellow silver test papers.

Merry Christmas

Manuel