# Help needed with silver extracting technique



## vladi57 (Jun 20, 2015)

Hi there! I am translating for someone who doesn't speak English. He has 100+ rolls of photographic paper 6" x 600' (the ones loaded in Kodak printers in the photo shops). These rolls are already exposed by mistake, but never processed chemically. This is why they are scrapped. His idea is to char these rolls in a pyrolysis process (mentioned here: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=85&t=22377) in a special vessel, and then from there to extract the silver using silver cell.

Question is is this possible as an idea? Any other, better, ways of doing it? Any advice will be highly appreciated!


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## MrMylar (Jun 24, 2015)

It may be possible to recover the silver by doing a test piece of approximately 2ft of the film and put it in some solution of sodium hydroxide/water. Let it get to a boil and the silver should start coming off within minutes. After that, just let the particles settle, and decant the water, then rinse well with hot water. After that, add some water to the vessel and a small amount of nitric acid and place it on low heat. Give it about 30 minutes +/- and after that, filter the solution with a coffee filter, and then after doing that, place a piece of solid copper in the solution. If there's silver, it'll start cementing on the copper and then it'll most likely start to fall to the bottom of the vessel once it's heavy enough to drop. You can always wiggle the copper piece to loosen the silver from the copper pipe.

Someone else may have another way, but this is the approach I would take, and especially if the test gave me positive results.

Hope that helps!


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## Lou (Jun 24, 2015)

Cut up 100 g of the material, precisely weigh it.
Incinerate it to ash, weigh it, and cupel it


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## rickbb (Jun 24, 2015)

If it were me;

I'd run it all through sodium thiosulfate and either precipitate the silver with zinc powder, or run the used fixer through a small electrolytic recovery unit. 

Unless your friend can control his temperature well during incineration he can lose silver as it melts around 1800F and vaporizes around 2200F.


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## goldsilverpro (Jun 24, 2015)

This data originally came from Kodak, I think. It's about the only numbers I could find. I'm not claiming them to be the gospel truth but the source seemed pretty reliable.

Depending on several variables (film speed, etc.), the silver on undeveloped color photo papers ranges from .037g to .139g per ft2. One roll has 300 ft2 of surface area (600 x 0.5 - one side). 100 rolls is 30,000ft2. Therefore, the total silver on those 100 rolls would range between 36 and 134 troy oz, or $572 to $2144, at a $15.88 spot. I would guess that selling it outright would bring in about 1/4-1/3 of the silver value, if you can find anyone that would even want it.

Chemically processing it yourself would very likely cost more than the total silver value. Way too much to process in buckets. Your friend would need some equipment unless he wants to spend the rest of his life working on this batch. Also, before processing, you would have to take it off the rolls. If you do this manually, there are about 400 layers of paper on the rolls. Then, you would have to cut it up. A better way, if it would work, might be to cut the rolls in half with, say, a band saw, if you can find a blade that would work on paper. Or maybe you could feed it from the roll into an industrial paper shredder. 

You could burn it to white (or light gray) ash, but you would lose about 25-30% into the air, in an open burn.

How much does 1 roll weigh? Knowing this might tell me more about the validity of the above numbers, although they are probably correct.

Personally, at this point, I wouldn't touch it with a 10 foot pole if I got it for free. It's not a good item.


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## rickbb (Jun 25, 2015)

Agree with GSP. Unless you have plenty of free time on your hands it will not pay for your labor to process by hand.

If you had access to automated photo film/paper development equipment, you could empty or turn off all the tanks that are not fixer and turn off the overflow replenishment for the fix and just run the rolls though. That would leave all the silver in the fix to recover.


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## vladi57 (Jun 25, 2015)

I would like to thank everybody for the answers. They help a lot! Now, going back to my interpreter role will translate my friend's thoughts:



> Special thanks to goldsilverpro! Completely agree with the calculations, but he will be surprised to know that beginner doctors or engineers in our country work for $2 per hour...But chemicals are cheap - liter of nitric acid is $1.50, same is for sodium hydroxide. The rolls are in my garage, and take space. I can burn them in the stove for heating purposes, not bothering with the silver,but why not trying to extract it? I am targeting burning, as the other methods are labor intensive and expensive. Resulted ash will soak in nitric acid and after this will run it through electrolysis - I have cell with graphite anodes and rotating stainless steel cathode I used it hundreds of tones of photographic solutions. If this method makes sense, what must be the concentration of the nitric acid? If this is bad idea, I can run the ash trough sodium hydroxide and then use corn syrup - is there any substitute for it?.


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## goldsilverpro (Jun 27, 2015)

Friend of vladi57 said:


> Special thanks to goldsilverpro! Completely agree with the calculations, but he will be surprised to know that beginner doctors or engineers in our country work for $2 per hour...But chemicals are cheap - liter of nitric acid is $1.50, same is for sodium hydroxide. The rolls are in my garage, and take space. I can burn them in the stove for heating purposes, not bothering with the silver,but why not trying to extract it? I am targeting burning, as the other methods are labor intensive and expensive. Resulted ash will soak in nitric acid and after this will run it through electrolysis - I have cell with graphite anodes and rotating stainless steel cathode I used it hundreds of tones of photographic solutions. If this method makes sense, what must be the concentration of the nitric acid? If this is bad idea, I can run the ash trough sodium hydroxide and then use corn syrup - is there any substitute for it?.


Friend of vladi57,

Damn, what country are you talking about? 

I don't think you realize how much bulk you will have until you remove it from the rolls, which you would probably have to do to efficiently burn it. And, here again, Burning 400 layers all to white ash (necessary) would be quite difficult and would take a long time if you left it on the rolls. 30,000 ft2 (a square 173' on a side) is enough to cover the floors of 2 small 3 bedroom houses.

Your cell is designed for hypo solutions. A nitric solution is different. For one thing, the crystalline silver will mostly all fall off of the cathode. If you use too much nitric, any silver deposited will re-dissolve until most of the nitric (more than about 4-5% free nitric) is consumed. At first glance, I don't care much for your process. I think there are better ways to do it.

Since the film is exposed, there will be a small amount of seed silver areas, but most all of the silver should still be as silver halides, AgBr mainly. 

If this stuff were mine, I would sell it and move on to something less labor intensive and something that would turn a profit. If I couldn't sell it, I would find out if a landfill would take it? If someone was holding a gun to my head, that's about the only way I would process it. 

I surely wouldn't burn it, mainly due to the potential 30% loss. There's no profit in this even if you were able to get all the silver, so I sure wouldn't want a big loss. It would be really dumb to burn it in the stove for warmth (maybe if the burner is outside and away from your residence). You have no idea how much toxic smoke the emulsion will generate. Do it wrong and you could kill somebody or, at least, hurt them, maybe badly. Everything about this project is labor intensive, whether you burn it or not. Pyrolysis (essentially, vaporizing) is better but, if the equipment design is faulty, it could easily explode if the off gasses reach a certain temperature and are confined. I'm thinking that the critical temperature for this is usually in the 400C-500C range, but don't quote me on this. If you got the material itself above about 700C, the AgBr would start vaporizing.

If a gun were held to my head and if I had your equipment, I would definitely first consider hypo. It doesn't remove the emulsion, like most stronger chemicals (e.g., sodium hydroxide) do and the worst thing you could do would be to remove the emulsion. That would make it a whole different ballgame, one that would much more equipment. Hypo is fairly innocuous. Anything stronger would likey weaken the paper and could even pulp it - you don't want that. I don't how how much of the AgBr would be converted to Ag by exposure but I would guess it would be nearly immeasurable. If it's more than I think, you could use a Blix solution instead of plain hypo to convert the silver to silver chloride and dissolve it. I would try to design a system that would run the film through the solution(s) directly from the reels, powering it by a take up reel and have some rollers built (or placed) into the tank(s). I've done this a couple of times on other applications. However, paper gets weaker when it is wet and could break. The tension on the paper would have to be fine-tuned. If you take the paper off the rolls, I assure you that you will be overwhelmed by the vast amount of bulk you have and now must deal with. 

I would first go through the Hypo solution and then follow in 2 or 3 rinse tanks. The speed of the takeup reel or puller would have to be slow enough to give it time to dissolve all the AgBr. Then, of course, run the solution through your rotating cathode system. You could just collect the paper coming out the end in cutoff drums or gaylords, although a take up reel would end up less cumbersome and more tidy. Paper soaks up solution and, instead of a take up reel, I would think that 2 rollers set close enough to grab the paper and pull it through, with the paper in between, would squeeze out most of the liquid into a container.

With some ingenuity, you could probably set all this up fairly cheap.

An alternative to electrolytic recovery of silver from hypo would be the direct precipitation of silver sulfide using a sodium sulfide solution. I like this process very much, mainly because you get it all, simply, with not a lot of equipment, and it's fairly fast. The best info on it was written by Juan Manuel Arcos Frank, our very good silver friend and humorist from Mexico. I wish you would post more, Manuel.
http://goldrefiningforum.com/phpBB3/search.php?keywords=silver+sulfide&terms=all&author=Juan+Manuel+Arcos+Frank&sv=0&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

The only experience I've had with photo papers was to analyze them for silver. However, in the early 2000's, I spent 3 days a week for 4 years as a consultant and analyst for a company that was processing a million pounds a month of scrap film. They also ran much silver chip, truck loads of canisters, and a few solutions that were run in rotating cathode units. During that time, I ran about 6000 assays (30 per week) on about every type of photo film under the sun. I did analyze a few of the papers but these were infrequent and about the only one I recall that was close to being valuable was a certain paper that was actually a negative - white letters on a solid black background. Called something like PXB, or some other 3 letter acronym. Popular in the'80s. Even with all that black, I'm thinking it only ran 0.025 tr.oz. Ag ($0.39) per pound, about 1/4 of rare earth medical film.

Good luck!


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## Westerngs (Jun 28, 2015)

If I had this material, I would probably go this route:

Assay
1. Take a 10 gram sample from each roll and run a fire assay to determine silver content. Note that a special procedure is required to accurately determine silver content in film or paper. I am not sure if maybe GSP has posted it here, if not I can post it.
2. Determine the cost of gas and chemicals to recover silver following procedure below.

Procedure
1. Ash the material in an airtight vessel where no oxygen will get in. This will greatly reduce any Ag volatilization (I'm not sure that's a word). Of course, this will also prevent the carbon from oxidizing, which will have to be dealt with later.
2. Once all material has been ashed and has cooled, run through a ball mill to reduce to powder.
3. Run a quick fire assay to determine approximate reducing strength of the ashed film (Again if GSP or someone else has not posted the procedure I can post). This will allow you to determine the amount of sodium nitrate required to oxidize the carbon during smelting.
4. Smelt with soda ash, borax and enough sodium nitrate to oxidize the carbon. Collect the silver in a cone mold.

To make this feasible you will need cheap borax, soda ash and sodium nitrate, hopefully they are cheap enough in your part of the world.

This is quite general, but if you search here you will find smelting flux mixes and ratios and quite possibly the assay procedures I mentioned.


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## solar_plasma (Jun 28, 2015)

I have no experience with this material, but since halides are more volatile than silver metal, I would expose it to the sunlight before I would incinerate, at least for the test sample. Nevertheless when two or more professionals say it isn't worth the effort, I would not spend it another thought.


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## goldsilverpro (Jun 28, 2015)

Westerngs, great to see you back.

I ran most all of those 6000 film assays using the Volhard titration method. The 1st week, or so, I did them by fire assay but that was much more expensive and much slower. Also, there were losses with fire assay which I had to compensate for. I usually prepared and ran 30 titration samples at a time, which took about 4-5 hours. I had 30 numbered 500ml erlenmeyer flasks that I used for this.

I ran 15-20g samples for the titrations. Usually, the film was already chopped. If not, I used scissors to cut about one 1/2" strip from the sheet, on the diagonal, from corner to corner, and then cut the strip into pieces. For 20g, this might take several sheets.

On undeveloped film or paper samples, before dissolving the silver with nitric, I first reduced all the silver halides in the samples to silver metal with a gram or two of one of the Kodak developers, which contained metol or hydroquinone. I have the exact developer I used written down someplace. Worked great.


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## vladi57 (Jun 28, 2015)

My bulgarian friend send me some image from a roll, a contraption that looks like part of professional photo-processor feeding system to which he will attach motor, and some ideas on how he will feed away the processed paper


According his experience from one roll can be obtained up to 15 g silver, which for the whole batch is 1.5 kg (3+ pounds). The expense he foresees is about $10 for power, and obviously needed amount of time to spend dealing with the processed paper. His enthusiasm is unbeatable, and I will do my best to support him – until the moment of a potential explosion… :lol: … possibility of which he claims is aware and prepared… :lol: :lol:


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## Westerngs (Jun 28, 2015)

Hello GSP,

I never really left, just did not visit as often as I used to. August of last year I volunteered for the board of my children's Christian school. I was blissfully unaware of the amount of time that would take up. 

I still continue to be on the board but summer vacation is here and I have some extra time. There were many projects last year and this coming school year I am starting a small science lab for the school, as it doesn't have one. I will soon be contacting companies like Fisher Scientific and the like asking for equipment donations like glassware and chemicals.

So, I would say it is good to be back, but that is not the case, I have been here all along.


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## tihi (Jun 29, 2015)

Hello ! I'm the one who needs help. I use google translator.Please you to accept my apologies for the funny English.This is my design for burning.The weight of a roll is 6 kg.What will be the weight of the material that remains after burning? The paper will be subjected to pyrolysis. The generated gases will support combustion.Once the prototype constructor is still alive, I think I'll survive. :lol:


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## Westerngs (Jun 29, 2015)

No way to know how much will be left until after the first burn.

Using that equipment, 100 rolls, one at a time, will take a long time and a lot of fuel. What do you intend to use as fuel? At this point, I am more apt to follow GSP's advice and sell it as is. 

Of course, if fuel is plentiful and cheap, and if the same can be said for chemicals, plus you have a lot of free time, I would do it just for fun.


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## tihi (Jun 29, 2015)

This is not the entire structure.There will be insulation and protective cylinder (drum) in the event of an explosion. The paper is coated with a thin layer of plastic. In our country do not accept it for recycling. The chemicals are cheap. I have enough free time, and I'm curious about the result. The initial heating will be wood, and then helps pyrolysis gas.


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## solar_plasma (Jun 29, 2015)

Only 7€ gross from one roll! You could get the same or better net selling it as paper craftstuff to schools and kindergardens. :mrgreen: It would make a nice, cheap wallpaper, too


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## tihi (Jun 29, 2015)

In Bulgaria, many people work for 7 euros a day.In Germany most people getting so per hour. Both countries are members of the EU.You claim that you are ten times smarter than us, or work ten times more than we?!For our children you do not care.


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## Westerngs (Jun 29, 2015)

tihi,

Just a friendly piece of advice, in this forum we stay away from politics and try to avoid insulting each other. Trespassing these rules can get you banned quickly.

Now onto the actual subject.

Since all necessary chemicals and labor appear to be inexpensive, start with the first rolls and make notes with pictures of everything that happens. That way, if things do not go as planned it is easier to either make corrections.

Good luck with your project.


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## solar_plasma (Jun 29, 2015)

tihi said:


> In Bulgaria, many people work for 7 euros a day.In Germany most people getting so per hour. Both countries are members of the EU.You claim that you are ten times smarter than us, or work ten times more than we?!For our children you do not care.



I demand an apology.


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## tihi (Jun 29, 2015)

solar_plasma said:


> tihi said:
> 
> 
> > In Bulgaria, many people work for 7 euros a day.In Germany most people getting so per hour. Both countries are members of the EU.You claim that you are ten times smarter than us, or work ten times more than we?!For our children you do not care.
> ...


You offer me to give photo paper, which is coated with poison , to the children !? I apologize for my reaction.


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## solar_plasma (Jun 29, 2015)

Coated with poison? Where? Proofs! Always open to learn something new.



> Both countries are members of the EU.You claim that you are ten times smarter than us, or work ten times more than we?!



I didn't invite you to the EU. I didn't even invite myself to this undemocratic bureaucracy monster. With the Euro our money is not worth even half of what it has been the 30 years before, called D-Mark. 7 Million people her are in fact working for 1€/hour, the "unemployed" - better to say kind of forced workers. Where did the money go? Well, you didn't get it. I didn't get it for sure. Follow the money...

But you are right, Bulgaria is very poor, especially most of the Roma, do I need to say more? Is the majority of Bulgarians better than their Romas? Don't throw stones while living in a glass house. This world is not fair. Though Bulgaria might be rich compared to some African countries.

I remember a debate in a facebook group, some stupid people talking about Bulgarians going from village to village for burglary, robbery, from hour to our it got worse, at last they claimed rape and stealing of children. I tried to calm them down, but against stupidity there is nothing to win. I have never had anything against your fellow countrymen, coming here to find work, to find there piece of luck. I never shut up, never retreat, when I can strike a blow for you or any other poor countries and immigrants from there coming here. Germany has a 1500 year old history of immigration.

Now, you claim that I think I am smarter than you guys?? As long as you refuse any apology, I have only two words for you in my mind, that I will not post here.


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## solar_plasma (Jun 29, 2015)

> I apologize for my reaction.



Well, now I have to apologize my last reaction! I saw this first, when I had sent my last message. Sorry, this topic got me getting a tunnel view.

So, everything's good from my side.


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## 4metals (Jun 29, 2015)

I think you both should chill out a bit, the likely issue here is a language barrier. So cut each other some slack and get on with the topic of refining.


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## tihi (Jun 29, 2015)

Okay!Peace.
Today it is raining.All set.At the first opportunity I will do sample.Thank you all for the advice.


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## santya (Mar 21, 2016)

Hello All, 

I am in need of silver extraction, which is dissolved in nitric acid & water. 

1kg Gold jewellery Purifying process which I follow:- 
1. Add 1kg gold with 2kg Silver and melt it, then sprinkle in water to create corn flakes. 
2. Add nitric acid to the corn flakes (silver&gold) which dissolve it and turn the liquid into blue color. 
3. Then Gold turns into brown mud form and silver remains in blue liquid. 

So, here i want to extract this 2kg silver in quicker and cheaper way ? how do it do that in simpler way. 
Right now I am using copper rods which is time consuming process.


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## FrugalRefiner (Mar 21, 2016)

santya said:


> Hello All,
> 
> I am in need of silver extraction, which is dissolved in nitric acid & water.
> 
> ...


Cementing on copper, as you are doing, is a standard method. Adding agitation to the solution, in the form of stirring, or an aquarium air bubbler will help the process along.

An alternative is to add a source of chloride ions, such as HCl or NaCl, to precipitate the dissolved silver as silver chloride (AgCl),but then you have to convert the AgCl into metallic silver through one of several methods described here on the forum.

Dave


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## goldsilverpro (Mar 21, 2016)

The more copper surface area, the faster the cementation. In about 4 gallons of silver nitrate solution in a 5 gallon bucket. I used 6 ea., approximately 15" lengths of 2" wide buss bar evenly placed around the bucket. I usually started it in the afternoon and it was usually finished when I arrived the next morning, unless it was a very cold night. 

To test it, I stirred it with one of the bars, let it settle a bit until the top was fairly clear, and then gently added a drop of dilute HCl or salt water with an eyedropper held close to the top of the solution. With any evidence of a formation of a white cloud, I let the reaction continue for a couple of hours and re-tested.

If yours isn't going that fast, it could be that you're using too much nitric acid. Any excess nitric will react with the copper before the silver cements. In my experience, a liter of 67% nitric, diluted with an equal volume of distilled water, will dissolve about 820 grams of silver in an open container with no lid. If covered, like as a watch glass on top of a beaker, it will probably take less nitric.


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