# Caustic Soda With Green X-Ray Films



## mda20 (Oct 16, 2013)

Hello Dear Kind Members,
Good Day! I usually recover silver from black x-ray films using Caustic Soda Process. This week I have tried GREEN x-ray films. I have followed the same process as with black film but I have gotten a different reult.

This is the sludge before incineration 


This is the sludge after incineration 

With black x-ray films I got brown powder. But here as you see, the yield is black that means it is not ready for melting. I spent long time for heating but it was wet and after cooling it became solid. I do not know how to deal with it. I think I have to do something before melting.

Can you help please?


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## rickbb (Oct 16, 2013)

What do you mean by "green" film? Do you mean film that has not been exposed and developed?


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## goldsilverpro (Oct 16, 2013)

With a few exceptions, I don't pay too much attention to the color of anything. Take a small portion and, from this point, treat it as you normally would and see what you end up with. To me, the proof is always in the pudding.


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## mda20 (Oct 16, 2013)

Thank you for your response.

I mean by green films are films that exposed to light or radiation but not processed chemically.

I think what I have gotten is silver sulfide, isn`t it?


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## goldsilverpro (Oct 16, 2013)

mda20 said:


> Thank you for your response.
> 
> I mean by green films are films that exposed to light or radiation but not processed chemically.
> 
> I expect what I have gotten is silver sulfide, is not it?



You are wrong on both counts. It's not what is called "green" film and it's not silver sulfide. Green film is virgin, undeveloped, rare earth, silver halide, x-ray film. When it is new, before light hits it, it's actually a green color. What you have is Dryview, not green film. Actually, the Kodak version is trademarked as "Dryview", but the term is usually applied to the dry type film from other manufacturers. The silver is in the form of silver behenate. I think, instead of being attached with an emulsion, the silver compound is attached to a mylar film, which is then attached to the PET plastic. It is very difficult to process. With caustic soda, it takes a lot of heat and time and the sludge is black, before incineration. Although there are exceptions, much of it it only worth about 40% as much as regular x-ray film.

I have the same advice. Process a small test lot of the black sludge and see what happens.


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## mda20 (Oct 16, 2013)

Thank you GSP. 
What I have are virgin, undeveloped, x-ray films but not dryview films. They look like those films in this pic.


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## goldsilverpro (Oct 16, 2013)

To me, it looks exactly like green, rare earth, x-ray film that is developed chemically. Unless they have something that is brand new, which I doubt, there are only 2 types: that which is developed chemically (rare earth) and that which is is developed by heat (dryview). "Green", rare earth, medical x-ray film is "exposed" by radiation, but is developed chemically. Virgin dryview looks like a sheet of slightly foggy blue plastic that you can see through.

Why do you care what color it is? Until you fully process it, you don't know whether or not you have a problem.


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## mda20 (Oct 17, 2013)

When I said GREEN films, I meant to compare with black ones. I got experience to deal with black x-ray films. But when I did the same process with green films, I did not get the same result. 

The black films would end to silver but the green ones would end to silver + sulfide. Is it right?


Now dear friends, how to deal with this sludge? How to convert it to pure silver?


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## goldsilverpro (Oct 17, 2013)

mda20 said:


> When I said GREEN films, I meant to compare with black ones. I got experience to deal with black x-ray films. But when I did the same process with green films, I did not get the same result.
> 
> The black films would end to silver but the green ones would end to silver + sulfide. Is it right?
> 
> ...



This thread has been a communication nightmare. I'm not a mind reader.

I would first incinerate the sludge, then melt it with Borax and Soda Ash. I would use about 30% of the ash weight of Borax and about 10% Soda Ash. In other words, if I had 10# of incinerated ash, I would blend 3# of Borax and 1# of soda ash with it and then melt it. Finally, pour, let cool, and separate the slag from the silver bar. That is exactly what I would do with the sludge from black film.

Tell me, step by step, going from unstripped film to silver bars, exactly how you do the black film?


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## Juan Manuel Arcos Frank (Oct 17, 2013)

May I say an opinion?


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## goldsilverpro (Oct 17, 2013)

Juan Manuel Arcos Frank said:


> May I say an opinion?


Certainly.


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## mda20 (Oct 17, 2013)

Dear GSP,

Here is the process:
- The films are dipped in Caustic Soda solution.
- Removing the black material.
- Adding sulfuric acid.
- After settling, the sludge is collected.
- Incinerate the sludge.
- Melt it to get pure silver.

I did the same process with the green films, but I have not gotten the same result.

Dear Manuel, I hope to know your opinion.


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## goldsilverpro (Oct 17, 2013)

mda20 said:


> Dear GSP,
> 
> Here is the process:
> - The films are dipped in Caustic Soda solution.
> ...



When you melted it, how did you flux it - what chemicals and how much? What result did you get with the green film?


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## mda20 (Oct 17, 2013)

For black films I add about 50% borax and 8% soda ash. I learned this from you dear Chris. 
But for green I never melt. I was afraid to waste it because incineration was not enough. I have to get brown powder but what gotten is black solid material as you see in the pic.


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## goldsilverpro (Oct 17, 2013)

All this time, I thought you had only dried it and had not yet incinerated it. I finally see what you're saying. You have incinerated it and you're worried that the black color is due to unburned carbon. May or may not be. I would incinerate it again. Use a large stainless frying pan and quite a bit of heat underneath. Stir it gently, often. When you're sure all the carbon is burned off, stop. At that point, treat it exactly like the black film.

I just thought of something. You treated the sludge with sulfuric and there is probably some still in there. Therefore, to prevent possible attack on the stainless, neutralize the sulfuric with a little caustic soda solution before incinerating.


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## chlaurite (Oct 17, 2013)

If you have undeveloped film as your starting material, couldn't you just skip right to using fixer to remove the unexposed silver as a halide, and then recover from the fixer, without needing to mess around with removing the substrate?

Sorry if that sounds like a stupid question, but from what (admittedly little) I understand about film processing, the fixer strips away the silver that didn't get converted to metallic silver by the developer; so if you skip the developer solution, the fixer should just strip everything, no?

Certainly sounds easier than lye and burning it. 8)


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## goldsilverpro (Oct 18, 2013)

chlaurite said:


> If you have undeveloped film as your starting material, couldn't you just skip right to using fixer to remove the unexposed silver as a halide, and then recover from the fixer, without needing to mess around with removing the substrate?
> 
> Sorry if that sounds like a stupid question, but from what (admittedly little) I understand about film processing, the fixer strips away the silver that didn't get converted to metallic silver by the developer; so if you skip the developer solution, the fixer should just strip everything, no?
> 
> Certainly sounds easier than lye and burning it. 8)



You could, but then you would have to deal with the silver in the fixer. In my opinion, the only good method for doing that is electrolytic but that requires special equipment with a rotating cathode. To me, stripping in caustic soda and incinerating the ash is easier, and cheaper.


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## MysticColby (Oct 18, 2013)

mda, those films look exactly like what I've been experimenting with recently.
I took the films, soaked in sodium hydroxide solution, decanted and filtered out the black powder (looked close to your first photo).
From here, I put it in a melting dish and heated with an oxy/propane torch (I just got one!) as it heated, it smoked a bit and shrunk. When it contracts, (I believe this is called 'sintering' but I may be wrong - when metal powders stick together tighter but don't melt) I then added some anhydrous borax and turned up the heat until it melted, then poured it into a ingot mold.
about 1,000 films (7-7/8" x 9-7/8") gave 15 grams of silver. The silver looks very pure. no oxidation I normally see from melting cemented silver. highly reflective. almost has a black tint to it, though, like it's dark or has an evil spirit held within.


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## goldsilverpro (Oct 18, 2013)

MysticColby said:


> mda, those films look exactly like what I've been experimenting with recently.
> I took the films, soaked in sodium hydroxide solution, decanted and filtered out the black powder (looked close to your first photo).
> From here, I put it in a melting dish and heated with an oxy/propane torch (I just got one!) as it heated, it smoked a bit and shrunk. When it contracts, (I believe this is called 'sintering' but I may be wrong - when metal powders stick together tighter but don't melt) I then added some anhydrous borax and turned up the heat until it melted, then poured it into a ingot mold.
> about 1,000 films (7-7/8" x 9-7/8") gave 15 grams of silver. The silver looks very pure. no oxidation I normally see from melting cemented silver. highly reflective. almost has a black tint to it, though, like it's dark or has an evil spirit held within.



If my math is right and, if you really had undeveloped, "green", medical x-ray film, like in the photo, 1000 sheets would weigh about 27 pounds and should yield about .18 oz/pound or 4.87 oz total. You sure it wasn't 100 sheets? That would yield about 15 grams.


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## Juan Manuel Arcos Frank (Oct 19, 2013)

With the written permission of GSP,let it be.

Mda20:

From the deep wisdom of Mr. Chris Owen,Great Master of our Brotherhood and worldwide known as GSP:

-“ THERE ARE MANY WAYS TO SKIN A CAT”-

But you have caught the cat from its tail and this is a big mistake.A cat must be caught by its neck,otherwise it turns and bites you,so let us catch the cat from its neck:

NaOH process(and almost all other processes) breaks down gelatin´s emulsion on the film then silver and organic material(if film is developed) or silver halide and organic material(if film is virgin) precipitate.Now,when you have only black films you have to deal with silver and organic material but when you mix black and green(virgin) films the mud obtained contains silver+organic material +silver halides(could be silver chloride or silver bromide) and here is your problem… the mud you have obtained contains silver chloride and silver chloride must be treated in different way,you have to add sodium carbonate to the mud and incinerates it at 400 C for half an hour,if you are not able to control temperature you can use a torch but remind that this solid reaction only takes place at mud´s surface so you have to mix frecuently the crush formed until all the mud has transformed into a crush pieces,then add some boric acid to make the crush easy to flow and rise temperature to 1100 C to get your metallic silver.

For future processing try to separate green films from black films…green films are easier to process than black films.You can dip them into fixer and recover silver using any method(electrolysis,zinc/acid,metallic replacement or sodium sulphide).There is a process, sodium hypochlorite,which works with developed and virgin films but again,mud obtained must be incinerated with sodium carbonate and boric acid.

I hope it helps.

GSP:

With all my admiration, gratitude, recognition and respect I thank you taught us how to skin cats, tigers, lions, snakes and other vermin


Kindest regards

Manuel


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## goldsilverpro (Oct 19, 2013)

The caustic soda used to strip the film also converts the silver halides to silver oxide. This converts to silver metal at a fairly low temperature. If the sludge is rinsed properly, most of the halides will be rinsed out. The sludge is then incinerated. Just in case some remains or in case a little of the silver halides are unconverted, some soda ash is added, along with borax, by blending it well with the film ash before melting.

We ran about a million pounds of film a month in caustic soda, with about 65% being medical x-ray. In most cases, the "green" medical was run in the same batches as the "black" medical. It was treated just like in the above paragraph. When you do have unconverted silver halides in the melt, it melts and, after the bar and slag cools, the presence of the silver halides is seen as an obvious layer between the silver and the slag. In every case, no intermediate layer was observed, indicating that our process was sound. As further proof, the yields from the 10,000# batches we ran were always within a percent or two (+/-) of the assays that were run on all the film.


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## Juan Manuel Arcos Frank (Oct 19, 2013)

goldsilverpro said:


> The caustic soda used to strip the film also converts the silver halides to silver oxide.
> Yes,Sir...if caustic soda used is hot and concentrated but...What temperature and concentration is Mda20 working?.
> 
> Have a nice day.
> ...


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## goldsilverpro (Oct 19, 2013)

We ran about 4% caustic at about 200F. When I had a tumbler setup in my own refinery, I ran 10% at about 140F - 150F with the same results.

I don't know what temperature MDA20 is using. He is using soda ash in his melts.


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## Juan Manuel Arcos Frank (Oct 19, 2013)

Yes,Sir but I am sure that mda2o is not working at the right conditions,otherwise he would get metallic silver,as usual he has done before he mixed black and green films.

I agree with you that NaOH process can work with black and green films.

Kindest regards.

Manuel


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## Juan Manuel Arcos Frank (Oct 19, 2013)

goldsilverpro said:


> Dear GSP,
> 
> Here is the process:
> - The films are dipped in Caustic Soda solution.
> ...


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## mda20 (Oct 20, 2013)

Thank you very much to my great teachers, Mr. Chris and Mr. Manuel.

I think I have to correct some informations to Mr. Manuel.
- I have no problem with black films. ( 3 kg of black films + 300 gm of NaOH + 10 liter of water)
- When I use Caustic Soda, I do not care to temperature. The yield was about 5 gm/kg of black films.
- I never never mix black films with green films.
- This is the first time I use caustic soda process with green films. I usually use electrolysis. I tried zinc process but I failed.

regards,


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## Juan Manuel Arcos Frank (Oct 21, 2013)

mda20:

According with GSP´s process you are working at low concentration and temperature.No problem with black films because NaOH only has to attack gelatine in film emulsion but in green films NaOH attacks gelatine and silver halides so in my opinion you have to rise concentration of NaOH and temperature to levels that GSP has posted to process both films,black and green.

About the mud you have obtained from mixed films you have to melt it with more Na2CO3 than you usually use because you have a mix of silver,organic matter and silver chloride.

Kindest regards.

Manuel


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## mda20 (Oct 21, 2013)

Thank you Dear manuel for these info.



Juan Manuel Arcos Frank said:


> mda20:
> 
> About the mud you have obtained from mixed films you have to melt it with more Na2CO3 than you usually use because you have a mix of silver,organic matter and silver chloride.
> 
> ...



This mud has been obtained from green films not mixed films.


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## Juan Manuel Arcos Frank (Oct 21, 2013)

Then all the mud contains silver halide(mostly silver chloride) and organic matter so process it like silver chloride.You have to mill the mud until it looks like flour,then add half of its weight of Na2CO3,mix well,heat it to 400 C and break the crush formed at the top,mix again and again until all powder has converted to crushes,add some boric acid to make it easy to flow and rise temperature to 1100 C.

Keep us posted about your progress.

Have a nice day.

Manuel


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## mda20 (Oct 22, 2013)

Thank you Mr. Manuel. I will never use NaOH process with green films. Although it does not recover %100 of silver, electrolysis is the best.

REGARDS


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## Juan Manuel Arcos Frank (Oct 22, 2013)

NO WAY!!!!!...you can use NaOH for green films because is a well proven process but remained what GPS has told about temperature and concentration.

Electrolysis is effective but is very expensive and requires high maintenance.

Kindest regards.

Manuel


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## mda20 (Oct 23, 2013)

Juan Manuel Arcos Frank said:


> Electrolysis is effective but is very expensive and requires high maintenance.


One machine will be bought for a once, that is all. Isn`t it?


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## Juan Manuel Arcos Frank (Oct 23, 2013)

RED FLAG!!!!!!.There is not an electrolytic process for recovering silver from films,I mean, first,you have to take silver away from films,second you have to dissolve that silver(or silver salt) and finally you can use electrolysis.All above mentioned is too complicated.

My advice to you is to still using NaOH process.Now you know that green films need more NaOH and more temperature,anyway you can process them as always but you also know now that the mud is silver halide+organic matter and you can get your metallic silver by melting it with more Na2CO3 than usual.Other options are fixer process or hypochlorite process for green films.

Kindest regards.

Manuel


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## mda20 (Oct 24, 2013)

Thanks dear Manuel.
I know that electrolysis is just used with fixer. Do you think that I can use electrolysis with any solution contains silver such as NaOH solution or nitric acid?

regards


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## rickbb (Oct 24, 2013)

You can get photographic fixer quite cheaply. A gallon will be more than enough.


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## Juan Manuel Arcos Frank (Oct 24, 2013)

No NaOH,nitric acid yes but rickbb is right,fixer is the best for green films.

Kindest regards.

Manuel


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## mda20 (Oct 25, 2013)

Thank you rickbb. Thank you Manuel.

I know that fixer is the best for green films. But what about NaOH solution, nitric acid or any other solution except fixer?


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## rickbb (Oct 27, 2013)

You should be able to use the normal NaOH process, it's just not the best way for virgin films.


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## MysticColby (Oct 30, 2013)

goldsilverpro said:


> MysticColby said:
> 
> 
> > mda, those films look exactly like what I've been experimenting with recently.
> ...



based on math I did beforehand, I was expecting about 50g. The main reason for so much less than 4oz is that not all of them were undeveloped. about 1/4 were undeveloped, 1/4 were developed and showed quite a bit of black, 1/2 were developed and showed almost no black. Still should of yielded ~40g in theory. My best guess is that the ones I have might be a cheap-o version. They are certainly new. I doubt they're high quality medical grade - is there such a thing as research grade film? I found a box they came in: BluBlot HS Cat. No. A8805 http://www.labsuppliesoutlet.com/component/option,com_lso/Itemid,1/prod_id,448/task,view_prod_item/
I can vouch for the 27 pound approximation. may of been a bit off 1000, but I did "count" them first because I wanted an estimate of silver / film (counted 50, made another pile the same size, stacked them, made another pile the same size, stacked them, etc.)


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## goldsilverpro (Oct 30, 2013)

Two possibilities:
1) You didn't get all of the silver
2) This BluBlot film may be an oddball variety that I've never seen before. Maybe it is very low grade.


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## mda20 (Oct 31, 2013)

For me the yield of 1kg of black film is about 5gm. Is that normal?


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## goldsilverpro (Oct 31, 2013)

mda20 said:


> For me the yield of 1kg of black film is about 5gm. Is that normal?



The overall average of running millions of pounds of developed rare earth medical x-ray film was 6.8g/kg (0.10 tr.oz./pound). However, the range was something like 4g/kg - 9g/kg. Chest x-rays usually ran on the low side, closer to 4g/kg - 5.5g/mg.


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## mda20 (Oct 31, 2013)

Thank you Dear Chris.


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