Silver from xray flim

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sena

Well-known member
Joined
Jul 21, 2011
Messages
208
Hi need help in recovering silver from xray flim , i have recovered silver using nitric leaching , the problem is while melting the converted chlorides , any alternate method please help, secondly how "fixer solution " is made?

Regards
Sena
 
Dip the film(s) in soda caustic solution, one
by one, that will clean them of the silver.
If enough innovative you can build a mechanism
similar to suspending laundry
 
Lino1406 said:
Dip the film(s) in soda caustic solution, one
by one, that will clean them of the silver.
If enough innovative you can build a mechanism
similar to suspending laundry
thanks for the information , i ll go for a trial tommorow.
 
Yes , the caustic solution removed every bit of the emulsion , i need to know the settled sludge is silver , and the solution is still dark , how come we know that the solution is free from silver?...
 
Silver is not pure because the mud contains gelatine rests,NaOH and silver.The only method which obtains pure silver directly is oxalic acid method,the process,step by step,is posted in this wonderful Forum.

Kindest regards.

Manuel
 
sena said:
Yes , the caustic solution removed every bit of the emulsion , i need to know the settled sludge is silver , and the solution is still dark , how come we know that the solution is free from silver?...

In my experience, the NaOH doesn't alter the silver compound on the Dryview, silver behenate. It breaks down the emulsion and the silver behenate breaks up and forms fine black particles, which are very slow to settle and difficult to filter. In production, we always ran everything through a big filter press.

What sayeth you, Manuel. For Dryview, didn't you once suggest adding ethyl alcohol to the NaOH? What does the alcohol do? Any dangers in doing that? Can the alcohol be added at this point? If so, how much? If so, will a cheaper alcohol, such as isopropyl or methanol work as well?
 
GSP,My Dear Friend:

You have such a nice memory!!!!!!,Yes,Sir,I said that about processing DryView films,alcohol makes emulsion easier to fall out,I think that emulsion in DryView films is different from emulsion in silver halide films,DryView films are developed by heat.

Ethyl alcohol(cheaper than isopropyl or methanol) could be used with good results,the process consists in dipping the films in a hot(60 C) solution of caustic soda,then add some ethyl alcohol and shake a little bit,the emulsion(with silver behenate) falls down nicely,pour off the solution,filter the solid and process it with the known methods.No one danger observed.DryView films contain very little silver.

Somewhere in my computer I have the process,step by step,I promise to post it ASAP.

Chris,behave yourself.Have a nice day.

Your friend:

Manuel
 
what about neutrlizing the solution with hcl?, i think we may get the sedimentation quicker .
 
Hi Manuel/GSP,

I am new here and new to silver recovery. Could you tell me a step by step guide on the recovery of silver using caustic soda?

All the best,

chandler_P
 
As I promised,here is the process to recover silver from DryView film.
---------------------------------------------------------------------------------------
Sena:

Recovering silver from films using nitric acid leaching is not a good idea,there are better and cheaper processes to make the same job,in example,NaOH process,oxalic acid process or iron chloride process.
--------------------------------------------------------------------------------------------

Chandler_P:

Being present GSP,it would be a daring from me to talk about NaOH process...ask GSP.
----------------------------------------------------------------------------------------------------------------------

Kindest regards to all of you.

Manuel
 

Attachments

  • Process for silver recovery from digital films.pdf
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I found this on recyclebiz.com.
"There are many processes for silver recovery from B/W films, offset negatives and radiographies. Combustion of film, nitric acid leaching, caustic soda leaching and CLOROX treatment have been proposed in this forum. Except combustion, all of them produce a silver intermediate compound that needs more processing to obtain pure silver, besides, all these processes release toxic fumes to the environment and nitric acid leaching and caustic soda leaching can cause severe burns.

The new process uses a low concentration of oxalic acid to attack the gelatine of the film and the silver goes down as a grey/black mud that only needs drying and melting to obtain pure silver. Concentrated oxalic acid is poisonous, please, use NIOSH/MSHA approved respirator, NIOSH approved gloves, splash goggles for eye protection and wear appropriate clothing to prevent skin exposure. Read MSDS for oxalic acid before start the process.

The process is quite simple, just make a 5%(weight or volume) solution of oxalic acid in tap water, heat this solution to 95 C, then submerge the films in the acid solution, in 20 minutes all the silver is removed. Once that all silver has been removed rinse the films and let them dry, you can sell the plastic base to a plastic scrap dealer.

Let the mud settle down, pour off the liquid solution, dry the mud and melt it, you will get 0.999 silver."

This might be an easier way to go. I have seen the oxaclic acid method mentioned several times but I could not find it with the search box. If there are other or better posts please post a link to them.
Mark
 
Manuel posted this process many years ago...if you want to know about silver it's either GSP or Manuel on here.
 
Juan Manuel Arcos Frank: I did not see anything about who first posted this. I did a Google search for the process and it came up. I copied it and gave the source in my post as I think it should be. I have tried to find the information on the GRF but without much luck. I do not wish to step on any toes or ruffle anyone. I only posted it in response to an existing post to try to help and I did ask for more input from others with more knowledge.
Mark
Below is the full post and yes it is accredited to the GRF and Juan Manuel Arcos Frank.

Re: X.ray films scrap
by Chris Owen » Sat Jun 12, 2010 7:21 am

The quote below is from goldrefiningforum.com. I have never used this method but it is claimed to work well. Keep the oxalic solution weak (the info below uses a 50 g/l solution) because if it is stronger, it is said that it might create sodium oxalate, which is explosive, although I have no idea where the sodium ion is coming from. Use a respirator and gloves when handling the oxalic acid powder, as it is toxic. After the solution is made up, it is supposedly not necessary to use a respirator. Also, it is said that the solution can be reused.

I have used about 4% sodium hydroxide for 1 hour at about 95C in an 40,000#/day film operation. Also, 10% sodium hydroxide, at about 60C or a bit less, will strip the film in about 10-15 min, although using it is more dangerous to use than the weaker solution. I have also used a proprietary enzyme/sodium bicarbonate solution, at about 40C, that will strip in about 10-15 minutes - this is about the safest solution to use although, since it ferments the emulsion, it really stinks. The problem with all these solutions is that the emulsion that is removed along with the silver must be incinerated before the silver is melted. Supposedly, this incineration isn't necessary with the oxalic acid solution.

No matter what chemical process is used, the films should be shredded before stripping, in order to get complete stripping and to keep the stripping time at an acceptable level. Unshredded films stick together when wet and this prevents the solution from getting in between them. I have seen both paper shredders and tree limb shredders used, but both tend to twist the film pieces and this reduces the bulk density tremendously. The best shredder is one that shears or cuts the film to 1/2", or smaller. That way, the pieces lay flat and you can get a lot more film in the tank. It is also better to use a tumbler. I once made one from a stainless tumbler out of an old clothes dryer that held about 150 pounds of film.

"There are many processes for silver recovery from B/W films,offset negatives and radiographies.Combustion of film,nitric acid leaching,caustic soda leaching and CLOROX treatment have been proposed in this forum.Except combustion,all of them produce a silver intermediate compound that needs more processing to obtain pure silver,besides,all these processes release toxic fumes to the environment and nitric acid leaching and caustic soda leaching can cause severe burns.

The new process uses a low concentration of oxalic acid to attack the gelatine of the film and the silver goes down as a grey/black mud that only needs drying and melting to obtain pure silver.Concentrated oxalic acid is poisonous,please,use NIOSH/MSHA approved respirator,NIOSH approved gloves,splash goggles for eye protection and wear appropriate clothing to prevent skin exposure. Read MSDS for oxalic acid before start the process.

The process is quite simple,just make a 5%(weight or volumen) solution of oxalic acid in tap water,heat this solution to 95 C,then submerge the films in the acid solution,in 20 minutes all the silver is removed.Once that all silver has been removed rinse the films and let them dry,you can sell the plastic base to a plastic scrap dealer.

Let the mud settle down,pour off the liquid solution,dry the mud and melt it,you will get 0.999 silver." Juan Manuel Arcos Frank, author
 
sena said:
what about neutrlizing the solution with hcl?, i think we may get the sedimentation quicker .

yup, this could be done but what does it release, i mean, does this release some chlorine gas? unsafe, but yes it's quicker to settle the silver by adding HCl. I tried it already bit not quite sure of the chemistry or safety of this.
let's ask for other members about this, i'm also in search for this, if it does result to emitting chlorine gas.
 
Dear kind members,

Good day.

I have tried the oxalic acid process but I have not get any result!

The process was;
500 gm of Oxalic Acid added to 10L tap water.
solution heated to about 90C.
3 kg of films submerged in the acid solution.

The result:
nothing happened. Films still black, no reaction.

Please tell my what is my mistake?
 
Mda20 you have to get it up to at least 95C, and it must be 5% by weight oxalic acid and the film needs to be in the acid for 20 minutes with I would have thought some movement to make sure all the silver drops out. Manuel really is the man to answer these points accurately but I think I have his process right.
 
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