Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ

Silver extraction from waste hypo/fixer solution

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Q. I need to extract silver just for a school project, so a thin strip will be sufficient. Can you please answer my queries:
-what concentration of sodium thiosulphate ⇦this on eBay or Amazon [affil links] to be used
-what voltage must be used
-anode and cathode, etc.
I need a minimal amount and the simplest procedure will suffice.
p.s. if there are any alternatives, please suggest.
Thank you.

Q. HEARD ABOUT SILVER REFINING FROM HYPO/FIXER, BY PRODUCT OF X-RAY DEVELOPING PROCESS CAN GIVE PUREST SILVER, IS THAT TRUE? IF YES, HOW CAN WE KNOW THE PERCENTAGE OF SILVER IN GRM/LTR? WHAT ARE THE VARIOUS METHOD OF REFINING THE EXTRACTED SILVER? IS IT AFFORDABLE?

Q. Hi Sir.....
I am Rajesh
Recently I had started silver recovery unit I want to know what is the process for color bleach in manual method.
That is I heard one manual method. In color bleach some chemicals will be mixed after mixing that chemical all silver content will come come down and waste water will come up.
I have to know what is the chemical is used to extract silver like this.

Q. I like to know which chemicals are used to extract silver from sodium thiosulphate. Is it possible to extract it from sodium hydroxide & sodium sulfide?

Q. SIR,
I WANT TO START A BUSINESS OF "SILVER RECOVER FROM PHOTOGRAPHY PLATE" .
PLEASE GIVE ME PROCESS OF REMOVING SILVER FROM PHOTOGRAPHY PLATE

Q. I want to know what are the equipments required for electrolysis method for silver extraction for anode, cathode, what tank is best? And can I recover 100% silver from this method.how much current have to use in electrolysis method? I know the chemical process also, so which one is best?

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Hi, Pradeep.

You say you know the chemical method, and you can see that hundreds of other readers got here first, looking for that information that you can offer. So please describe the chemical method that you know. Then maybe people can compare it to the electrolysis method for you.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 7, 2011

I have searched for advice on recovering silver from spent film fixer. I mostly found questions on this site with no answers. This is what I deducted. Both developer and fixer start out clear. The developer turns muddy but the fixer stays relatively clear. Both are very alkaline. The developer is waste. The fixer needs to be pH adjusted to about neutral using sulfuric acid (battery acid ⇦this on eBay or Amazon [affil links] ). The reaction was very weak in the alkaline solution. I used OOOO fine steel wool and immediately saw a chemical reaction. The solution turned milky white and a dark precipitate dropped. In a different container, I used powdered zinc. The reaction was much stronger. I have photos, but don't know how to post them here.

Now for volume processing, I plan on adjusting the pH then 1st precipitating with the steel wool, then decanting into a container with powdered zinc for a second round of precipitation.

Theoretically, I can purify the silver in the steel wool tank by exploiting melting points of silver vs. iron. Theoretically, I can purify the silver in the zinc tank by re-dissolving the melted metal nugget in nitric acid, precipitate the silver with table salt, wash with distilled water and bring to a boil. The silver chloride should remain as a precipitate while the zinc should go back into solution.

I need to investigate stripping film for silver recovery next. The oxalic acid post was interesting.

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Ed. note: Attach the photos in email to mooney@finishing.com

Q. I know how to extract silver from waste fixer chemically but the process is somewhat difficult. I use the following chemicals sodium sulfide, caustic soda ⇦liquid caustic soda in bulk on Amazon [affil link] sodium nitrate ⇦this on Amazon [affil link] borax soda ash this process finally I get the black powder which is to be melted at high temperature.

Is there any other method to extract pure silver chemically without melting the powder. I want the method to extract silver without melting chemically.

Q. Respected sir,

Now I want to extract silver from fixer solution and x ray films.

To date I use sodium sulfide, sodium hydroxide, borax for fixer solution but I got black metal with impurity of Pb sisa) according to goldsmith and it is breakable in nature.

Please give me proper instruction (step by step) for fixer solution and x-ray films.

Thanks.

Q. Dear sir: once burned x-ray films and having the ash, what's the next step to obtain silver by electrolysis?

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September 1, 2011

A. I have read many forums and thousands of threads but this one is amazing! Hundreds of questions. A few answers that are succinct and to the point.

The chemical solution:

Chemistry is fun if you learn a little about it. The frustrating thing about chemistry is when you want to work with chemicals and involve yourself and possibly others in a chemical process with NO knowledge of what is going into the process, what is happening in the process and having NO knowledge of what result to expect from the process.

"What chemical(s) do I add to an UNKNOWN solution to create high purity silver?"

Answer: There is NO answer because there is NO possible answer to what will result from an unknown.
Better question: What chemical(s) do I add to a KNOWN solution to recover silver (of unknown purity).
Example: Recovery of silver from silver chloride...

The chemical reaction of Sodium Hydroxide with Silver Chloride results in a KNOWN combination of compounds; sodium chloride, silver with hydrogen and oxygen.

NaOH + AgCl --> NACl + Ag + H + O

In photography, Sodium Thiosulphate (Na2S2O3) combines with silver bromide (AgBr) to create a complex compound...

[Ag(S2O3)2] with three spare electrons + Br with one spare electrons. These are ionic compounds.

From what I have seen, the recovery is done with proprietary chemicals.

Electro-chemistry is MORE fun than chemistry!

The answer was given above in the thread. Using a power supply with a graphite anode and stainless steel cathode, it is possible to electro-win or plate the silver out of solution onto the stainless steel plate (electrode).

How much voltage?
How much current?

"Recovery and Refining Of precious Metals"
by C.W. Ammen

on AbeBooks

or eBay or

Amazon

(affil links)

Answer: There is no specific answer because the question (again) has no specific identification of the concentration of the solution or the temperature of the solution or the size of the electrodes or the spacing between the electrodes.

The voltage required and the current required depends on all of the above.

What is recovered?

There is NO answer to this question because (again) it is impossible to answer. What metals are in the solution? Is the solution contaminated with other metals?

Depending on the quality of the solution, you will get silver in the form of crystals or "sludge". The sludge and/or crystals can be melted into impure silver.

The book, "Recovery and Refining of Precious Metals", by C. W. Ammen is one of many recommended publications on the subject.

Precipitation:

Less noble metals... Copper, Iron (nails) will precipitate silver from photographic fixer. (it's actually electro-chemical without a power supply)

It has been an impossible thread! The answers were impossible! The answer IS possible with a knowledge of chemistry and the willingness to apply chemistry AND electrochemistry to find the answers to the above questions.

What are the economics of silver recovery?

Answer: The economics are determined by subtracting the cost from the revenue.

The answer is impossible without knowing what the costs and revenues are. Where in the WORLD are you? What does labor cost in India vs the US? Certain people have replied with knowledge and experience that say it is not economical. Controlling efficiency and cost while maximizing the revenue side while noting the price of silver today will affect economics.

Question: Will this END the impossible questions?

Answer: NO. There is no end to impossible questions!

Good luck!

Chuck Merritt
- Cochise, Arizona, USA

Q. I am planning to start silver extraction business part time from waste photographic hypo solution. I am Photographer. I shall be very thankful if you please answer some of my questions.

1. Various chemical methods employed to extract silver on small scale. Its exact procedures?
2. Electro-Chemical method (Through Electrolysis) Its feasibility?
3. Procurement of plant and machinery

In nutshell I want to know the details of easy and profitable practical method for the extraction of Silver from waste Hypo fixer solution. Please guide accordingly. I shall be very thankful to you

Q. Dear Sir,

Kindly provide me the exact detail of two things, which is required to separate silver from fixture, mentioned below:

1. Which 3 chemicals is used to separate the silver from fixture.
2. How much the quantity of chemicals to be mixed in fixture. and which chemical should be used first and what the next step.

Desperately waiting for the reply

Thanks

Q. Sir, can anyone help me in recovering the silver from the QSS lab bleach and stabilizer? And which chemicals are used for the precipitation and for the melting?

Q. Hi,
I'm Rathod from Bangalore, actually sir I'm planing for setup silver extraction machine and I'm new for this kind of business so I need help from you sir , means whether I can do or not, is it profitable or what and do I get the raw materials in Bangalore.
Thanking You

REGARDS

Q. Dear sir, good morning, I'm Rajesh from India; I want to know which chemicals are used in silver extraction from x-ray fixer ? What is approximate amount of these chemicals in 100 ltr? How to complete this process method? Thanks sir

Q. For silver recovery from x-ray fixer what should add sodium sulphate/sodium sulfide? Please guide me.

Q. I am a wet plate and Daguerreotype photographer. I use a 1% cyanide solution as a fixer when making tintypes. After fixing several plates the bath gets exhausted; it no longer clears the photographic plate as it is saturated with silver. I have tried using this solution with a fine silver anode and a copper or brass cathode. I get a durable silver coating, but after a minute or two I get a yellow scum that needs to be polished off the plate. Is this a half-decent way of getting a .5 mil coating? I would love to reuse this bath both to reduce any haz waste and reclaim some silver. One more thing, the silver is from silver nitrate in water, soaked into a colloidal matrix. There is a minute amount of cadmium in the colloid, roughly .05 g per litre

The cath/anode are 5" apart, I am feeding it 2 volts at .2 A

Q. I have done the metal replacement method to recover the silver out of spent fixer. I used a copper tube and just left it sit in the fixer for a few days and now I have the black sludge. How do I refine this? I have looked and looked but have not found what to do with it.

Hello and welcome.

l have gone through the maximum questions posted over there and found that so many people are aware to the extracting of silver from solutions but not revealing their methods; but a very few philanthropic personalities have answered nicely.
I salute & thank all of them who are Best Guide for ...seeking help.
thanks.
Jai Hind!!!

A. SILVER FROM PHOTOGRAPHIC SOLUTIONS
Various people are trying to recover pure silver by various methods. I feel the quantity involved for most is too small to get it in to any complex processes / costly equipments, which will make is less economical / viable.

Simplest processes are metal replacement. i.e., less noble metals dissolves in solution precipitating more noble. Say, copper, iron, etc. will precipitate silver from its solutions.

Copper (sheets / turnings or iron turnings, iron wool used for paint polishing (do not try iron wool used for cookware cleaning; it contains other metals). Manufacturers sell 000 to 0000 grade at about Rs 130/kg (USD 1.95/kg ). For your purpose use only pure Iron wool, Iron wool 0000 grade has highest surface area. Thin metal turnings will have more surface area.

HIGHER THE SURFACE AREA, FASTER IS YOUR RATE OF RECOVERY

In a simple set up you take 20 liter waste solution in a plastic bucket / HDPE drum, Take Scraped copper rod /thick; scrape piece, thin sheet turnings are wrapped around with synthetic thread. Alternatively use a iron rod and wrap iron wool around it. Put it in non woven bag /polyester/nylon bag, put this bag in waste solution. You will get most of silver with sulfur/sulfides and some other metals as a black sludge in the bag. It takes 12 to 24 HOURS.

For faster cycle you can hang a graphite electrode on other side of the bag. It should not touch (Say about 2-3 inches apart). Use discarded car battery with at least 3-4 cell working or 29-25 ampere DC rectifier; connect negative to graphite and positive to center rod/scrape of copper / iron.

Little stirring / vibration will help collect all silver sludge at the bottom and becomes more efficient,

You can use bright sanded copper strip to check if any more silver is left behind in solution. In few seconds it turns black if you have 500 mg/ltr or more. If it takes more than 5 mins to turn slightly brown-black it is close to 20-30 mg/ltr.

KINDLY NOTE IN MOST COUNTRIES IT IS NOT ALLOWED TO DUMP ANY SILVER over 5 mg/ton IN DISSOLVED FORM. It's a very toxic heavy metal. KINDLY REMEMBER.


To above dried sludge add, say, 1 kg sludge + 250 gram soda ash + 50 gram borax + 200 gm Sodium nitrate. Fire it in a graphite crucible slowly to 1150 °C. vibrate few times, you should get pure white silver of 99%+

*BORAX is used to lower meting temperature of glass phase of sludge impurities
*Sodium nitrate is used to avoid evolution of toxic SO2 gas
EXTREMELY IMPORTANT: when using Sodium nitrate, as gelatine from the waste soln. Makes highly explosive combination. Melt smaller quantities to start with, very slowly raise temp, from 600-900 °C.
*Clay / ceramic crucible are not suitable as soda ash, borax, etc. will melt the furnace.

Q. I work for a company that manufactures fire suppression for commercial airlines. Part of that process is x-raying the bottles for cracks in the welds.
We use a CPAC ARU-1200 which is a silver recovery electrolysis system to minimize the amount of silver or heavy metals that drains into our industrial waste line. After spending some time figuring out what this system did and its process, I am stating to recover what I think is some type of silver building up on the Cathode (which is made of stainless steel).
What do think the purity is if it silver? Does it need further refinement?

Thank you so much. I really appreciate all of your hard work and effort in making this a website that anyone can use to educate oneself for a better end result.

Dave

A. Hi Dave. I expect that this would be silver suitable for shipping to a refiner. But guessing isn't a good way forward. I would suggest having a sample of the x-ray effluent analyzed before treatment so you know how much silver was actually in it, and have the recovered silver weighed and analyzed so you know what percentage you recovered. With these two numbers you have some measure of what you are accomplishing, whether you re operating efficiently, and whether it's even worth the effort; without those numbers, you really don't know much. Good luck.

Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
December 2016

A. If the deposit is very white and hard, it could be as high as 97-98% pure. If it's black, smelly, and loosely adherent, it could be as low as 80-85% pure. It never is pure from those electrolytic units. The impurity is sulfur. The brittle silver is broken off of the stainless steel drum by tapping it with a hammer.

It is purified in a gas crucible furnace. Some borax is added to the silver along with several lengths of rebar (long enough to protrude from the top of the crucible, so they can easily be removed). Some of the iron from the rebar combines with the sulfur ⇦this on eBay or Amazon [affil links] in the silver and this iron sulfide goes into the borax slag which floats on top of the molten silver.

When the reaction is complete (in an hour, or so), the rebar is removed and the molten slag and silver is poured into a large cast iron rectangular or cone shaped mold. When cool, it is dumped out of the mold and the slag is broken away from the silver. If done right, the silver can be 99.9% pure, or better.

Chris Owen
- Nevada, Missouri, USA
December 18, 2016

Q. Dear sir
I just heard about this business. I just want to know what are the companies sell this used hypo/fixer.

A. Hi Malik. We are now in the digital age so I suspect there are ever declining sources for this silver-bearing photographic fixer solution, but you could check with local hospitals and x-ray laboratories.

Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 2018


August 27, 2018

A. There must be a sufficient amount of silver to be recovered before attempting to recover it from the material because the cost of equipment needed must be justified.
There is no way to condense the entire subject in brief post.
some posts ask how much silver can be recovered from an Xray film. It depends on how large a surface the film has, how much of exposed area on it ( whites, transparent parts of it mean total absence of silver in those areas of exposed surface where hypo just removed it from film.
Others ask about recovering the silver that is in the hypo.
Yet others ask for stripping the image on the material and recovering silver from emulsion.
Each has its own process and yes, if there is enough yield projected then you can proceed with your project.
The fixer solution can be treated for recovering silver in recovery machine by electrolysis.
Film and paper can be stripped off and the gel remaining can be returned to recovery machine.
We also use special bucket type of recovery equipment that will recover silver but will take very long time for it because gravity fed cans work drop by drop.
Recovery machines will treat 7 to 20 gallons in about 17 hours.

John Abram
Master Technician - Los angeles California USA

Q. Dear sir I just came across this very interesting and mind blowing business. I am a graduate of Chemical engineering; please I want to know everything that has to do with extraction of silver from waste. I want to also know various waste from which silver can be extracted. I am very much interested. Thanks