Method for recovering silver from photo chemicals

[Ignatz61]

Hi all,

I am trying to learn how to recover silver from darkroom chemicals.

Hoke gives three ways:

1. add sodium suphide silver drops as a black silver sulphide

2. Add zinc powder. This she says results in cleaner silver but is slower.

lastly, She describes a silver stripping cell that uses low voltage but huge amperage.

I have tried the zinc but after sitting overnight nothing seems to be happening. The solution is very basic when tested with litmus paper it comes up a nice blue.
Do I need to add acid to the solution to drop the ph? If so, What would be the acid of choice, or does it matter?

Am I going the wrong way with this? Any help would appreciated as I think I have a continous source of these chemicals for free.
Thanks,
JOHN

 

[Lino1406]

Silver solution in a fixer?

 

[Ignatz61]

It's a mix of fixer and developer, they dump all the day's chemicals into a container.
it is very alkaline, The zinc I added isn't doing anything.
I am wondering if I could add HCL to it to make it acidic or if electroplating is the best solution?

I know silver is cheap and this won't replace my salary but the solution is free so anything I get out of it is profit (Less chemnicals etc.). Plus I find all the refining/recovery procedures facinating. I am a concrete learner so I have to do something inoder for it to totally make sense. Thats why I have posts in so many different places, I am trying as many things as possible. Platinum in O2 sensors/spark plugs, gold plate in a stripping cell, Photo/xray film in oxalic acid.....

 

[Lino1406]

That it contains a fixer and if
it's really very basic then
take a sample and add
some formaldehyde

 

[Ignatz61]

Thanks,
I am looking for some formaldehyde, in the meantime i put a small amount in a test tube and added some HCL.

The solution turned from dark to an off white kind of ivory color, No notesable fumes. after a day it turned clear with a black percipatate that coated the sides and formed a fairly solid disk on the bottom. It held it's shape when I pulled it out with a small spatula.

Is this black precipataion the silver?
if it is what now? melt and put in parting cell?
Is till have a jug full and more on the way.
Is there an advantage to having them put the developer and fixer in separate containers?

 

[Lino1406]

Only the fixer is useful
You should have Ammonium smell
To test silver, dissolve in HNO3 - should be kind of yellow
and add some K2Cr2O7 solution - should be red
Now you know all I know

 

[Juan Manuel Arcos Frank]

Here are the J Series

Manuel

 

[Juan Manuel Arcos Frank]

The J215 and J217

Manuel

 

[Juan Manuel Arcos Frank]

Ignatz 61:

Well,you have asked for help,so here it is:

The first thing you have to do is reading all the "J Series" from Eastman Kodak that I have posted for you... here the theory of silver recovering from photo processes is magisterially exposed.

The second thing that you have to be able to do is measuring the silver content of your spent fixers,I assume that you do not know how to do it,do not worry,here is a method created by me which is cheap,easy and fast:Get a copper wire,take off its plastic cover and dip it into your spent fixers,if they have silver the wire will get silvered according with the silver concentration:

If the wire gets silvered in ------- Silver Concentration

1 second-------------- 12 gr/lt
2 seconds------------- 10 gr/lt
3 seconds------------- 6 gr/lt
4 seconds------------- 3 gr/lt
5 seconds------------- 1.5 gr/lt

To use the zinc recovery method you have to down the pH of your spent fixers to a 5 level,you can do this adding a 5% solution of sulphuric acid (H2SO4) .To prepare this solution you have to deal with concentrated acid,this is a risk and you have to use gloves,apron and eye protective lenses because H2SO4 is very dangerous and could produce severe burns.

In a plastic container add 19 lt. of tap water,CAREFULLY and SLOWLY andd 1 lt of H2SO4 concentrated,let the acid flow through the container`s wall,NEVER add water to the acid,if you do that the acid will spatter and cause you severe burns.Stirr gentely.

The rest is easy..check your silver content,add 1 lt of 5% H2SO4 solution to each 5 lt. of spent fixer to adjust the pH and add the same weight of zinc that you have of silver (i.e. if you have a silver concentration of 3gr/lt,20 lt. of spent fixer then your silver content is (3gr/lt)(20lt.)=60 gr of silver,so add 60 gr. of zinc....and 4 lt. of 5%H2SO4 solution) stirr for 5 minutes,you will see that a black precipitate is formed,this black precipitate is pure silver,so let it settle down,pour off the liquid,filter the black mud and put it into a container,add some hydrocloric acid to dissolve the zinc,you will see that the mud starts bubbling,when the bubbling stops that means that the zinc is completely dissolved.Let settle down,pour off the liquid,wash with tap water,filter the black mud and melt it with a mixure of borax and nitro salt,you will get a pretty fine silver.

Mrs. Hoke is right about the sodium sulphide (Na2S) process,it is cheap,easy and fast...BUT if you use more Na2S than nedeed you will produce hydrosulphuric acid (H2S) which is toxic and smells like rotten eggs.To avoid this risk check first the silver content of your spent fixers,then add the same weight of Na2S than silver weight you have(i.e. if you have a 3gr/lt silver concentration,20 lt. of spent fixer then you have (3gr/lt)(20lt)=60 gr of silver,then add 60 gr. of Na2S).When you add the Na2S to the spent fixer you will see that a black mud is formed,this mud is silver sulphide (Ag2S),check the silver content with the copper wire until the wire stills clean for more than 20 seconds,this will cause to precipitate all the silver in the spent fixer.Let settle down the black mud,pour off the liquid,filtrate the mud and it is ready for the refining process,you can use the nitric acid process,this process is posted in this wonderful forum.

I hope I did not crushed you with so many information.Keep me informed about your progress.Do not quit...silver recovering from photo processes is such a good bussines.

Best Regards

Manuel

 

[Ignatz61]

Juan,
Wow! Thanks for all the info. I will be studying it tonight.
I will post my results. I have 1 batch of about 3 liters done. I just added HCL to the solution and after 2 days I have a white precipitate (spongee looking). I am going to melt it tomorrow and see what happens.
I am thinking it is like filleting your first fish. It's always a hack job but each one gets better as experience grows.

Thanks again
JOHN

 

[Juan Manuel Arcos Frank]

It is OK John,but try first the Ag2S method and zinc method...if you just add HCl to the spent fixers you will precipitate all kind of salts...except those that have silver..by the way..now that you know how to measure the silver content,how many silver do your fixers have?.

Have a nice day

Manuel

 

[Ignatz61]

Hi Juan,

I melted the sponge and got only small amounts of silver metal. I still have a jug of nasty smelling brown liquid.
I think I have this batch too messed up to get much out of it.
My next batch I will check the silver content as you suggested and will Process with the AG2S method and will post my results.

The Kodak info in the pdf's is very informative, Thanks again for posting them. They are good reading for anyone interested in photo chemical recovery.
JOhn

 

[Juan Manuel Arcos Frank]

John:

Probably the silver content is low..now you know the key in this bussines in the silver content.Here I am for what you need.

Manuel

 

[Daport]

Good day to all!

I have been reading about silver recovery from this wonderful forum for quite some time now and I really have to say that I have learned a lot . I have some questions regarding the silver recovery method using zinc powder from used fixer. I tried a small batch of 1 liter fixer (X-ray Fixer made by Kodak) and dropped the zinc powder directly to the solution. At that time I have no idea on how to estimate the silver content and then came up with Mr. Juan Manuel Arcos Frank's post about the copper wire test which is really genius!

I immediately saw the fixer precipitate a black substance, drained the fixer solution and retained the sludge. washed the sludge with 15% HCL until there is no more bubbling. then rinsed it again twice with tap water. After drying the powder I melted it and got tiny balls of silver . All of this I did without adding 5% HCL.

My question is,

1. Do I have to check the PH of the fixer solution
2. Is there a way to get rid of the smell from the fixer solution without loosing silver in the process?

Thank you for your time an please excuse my ignorance on the matter.

John

 

[Juan Manuel Arcos Frank]

Daport:

Metallic replacement reaction between zinc and silver complex is accelerated by lowering pH(near 5).Some fixers are pH 5 so there is no need to add acid to low pH but if reaction is not fast enough then you have to add acid.Checking ph from spent fixers is advisable.

Look,there is a way to get rid from fixer smelling...just do it outside and in a well ventilated area.

Kindest regards.

Manuel

 

[Daport]

Thank you very much for the reply Sir Manuel.

I will decrease the Ph as sudgested. One of these days I will try your formula on how to convert silver sulfide into metallic silver. As of the moment I still have 15 gallons of fixer to run, I used a flat copper bar (about a 1/2 inch wide and 4 inches long) to test the fixer solution, soaked it for about 1 second and it instantly grayed the copper (thanks of course to Mr. Juan Manuel Arcos Frank's copper method).

Currently I am still looking for the right chemicals to buy and is currently reading the pdf file by Mr. Juan Manuel over and over so that I cannot skip a step/procedure. because I have read in this wonderful forum that it produces toxic gasses. Sir when using your sodium/potassium method is it ok to precipitate the silver in the original container itself and just screw the cover back? I mean just to trap the harmful gasses that it produces.

Thank you.

John

 

[MarcoP]

Sir when using your sodium/potassium method is it ok to precipitate the silver in the original container itself and just screw the cover back? I mean just to trap the harmful gasses that it produces.

Thank you.

John

It will create so much pressure to make the container explode.

 

[Daport]

Hi everyone! I successfully cemented the silver from the fixer solution using the zinc method. Unfortunately some the chemicals are banned here in my country so i was unable to use Manuel's method.

I have a few questions. While doing the cementation I tested the fixer solution and got a ph value of 5. Then i proceeded to cement the values by droping zinc dust cp grade while agitating the solution. Whin i was about to wash the cemented silver with diluted hcl i got this white solution.

Is this silver chloride?

Thank you

 

[butcher]

The zinc cemented elemental silver as a powder, by adding HCl, you turned the silver into silver chloride, (complicating your recovery), now you will need to convert it back to silver metal.

 

[Barren Realms 007]

The zinc cemented elemental silver as a powder, by adding HCl, you turned the silver into silver chloride, (complicating your recovery), now you will need to convert it back to silver metal.

A little clarity in this statement for new members. It didn't covert the already cements silver to silver chloride just the silver that was still left in the solution that didn't convert from the addition of the zinc. When adding something to a solution like this it is always good to take a small sample and perform a test to see what you are adding will do to your solution.