The authoritative public forum
  for Metal Finishing since 1989
  

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Electrolytic Refining Process of Gold

 

Q. Dear Sir,

I would like to know how to recover Gold from Silver Sludge which comes out from the Wohlwill Cells (Electrolysis). We are actually washing it by ammonia. And today through your site I came to know that it is dangerous. Please let me know that how can you recover Gold from that Silver Sludge. I would appreciate if you could answer this question of mine.

Waiting to hear from you at the earliest.

Kind Regards,

Pulkesh Patel.
- Bombay, Maharashtra, India

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Q. Dear Sir, I am helping a patron of mine do research on the electrolytic refining process of gold (primarily) and silver (secondly). We are having trouble finding resources that explain the process fully, but I have ordered Hummel's Wohlwill electrolytic gold, platinum, and palladium refining. Are there any more must-have titles as far as the process itself is concerned. My patron has been doing this for a while as a hobby but is looking to expand his knowledge. Any help you can provide is appreciated.

Carolyn G. Garner
regional library - Mechanicsville, Virginia
1999

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Q. I have a refining workshop and I refine gold by adding silver double weight of gold and melting it making small granules and boiling it with nitric acid until all impurities are dissolved in acid gold becomes powder and then washing the powder neatly then melting the powder gives me 99.20 purity gold. Sir if you have any procedure please post it.

Soni Yogesh M.
- Ahmedabad, Gujarat, India
2002

Book name which contain procedure of cyanation process & smelting process? I WANT THE INFORMATION ABOUT VARIOUS GOLD REFINING PROCESSES. BASICALLY CYANATION& SMELTING AND ELECTROLYSIS.

Prasad Gangadhar Gosavi
assistant manager refinery division - Mumbai, Maharashtra, India
2006

I have a small refining shop in the Philippines. We refined gold through chemical means, that is by using nitric acid. I have plenty of silver and copper nitrate solution as a result of this, I want to refine my silver into a 99.99%, I heard that we can achieve this through electrolytic refining,using 2 methods Thums and Moebius, does anyone knows how is this done?

Mark Yap
gold refining - Cebu, Philippines
2006

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Hi, Prasad; Hi, Mark. Do you have any update since Bill Vins' recommendation? Were you unable to find a copy of the book that he told us about? Or did you find it but it lacked that info? We'd appreciate an update to keep the page as current and useful as possible to as many people as possible. Thanks!

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2006

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2006

Just a follow-up... The difference between chemical and electrolytic refining lies in the purity, In chemical refining, you can not achieve a 99.99% purity. The most you can get for gold is 99.92% that is for single refining and only if you spend a long time putting a lot of nitric acid, usually it's between 99.60 to 99.80%. You can achieve 99.99% through electrolytic refining sometime called electrorefining. The hard part is silver, if you use copper to precipitate silver nitrate solution, you can only achieve 99.40% purity, depends on how you wash it thereafter, Because the silver sludge that formed acts like a sponge and starts absorbing your copper in the solution. and 99.40% I believe falls below international standards in refining which is 99.70%, that is for silver. For gold it's 99.50% . If you use sodium chloride or table salt for precipitation you might get a higher recovery than using copper. But the hard part is the temperature required to melt your precipitated silver into metal is quite high.and due to the chloride, the volume is big but the resulting metal is small. It's best to use electrolytic refining if you want a higher purity!

Warning: Nitric acid is very corrosive and dangerous, its the main ingredient in nitroglycerine, used to make bomb! To refine gold you have to lower the percentage of gold by using silver or copper, theoretically to 25%. meaning the gold content of the metal is 25%. But in practice its best to lower it to around 15- 20%. After putting nitric acid you heat it to boiling temperature until it stops giving out red smoke, Be careful as bubbles form and might overflow, so just lower the fire. then you should wash it with water pouring all the solution into a pail and leaving the solution for a few days, there is still gold in it! Then you have to press or ground the powder( you can use a spoon, you are using a stainless bowl during refining ) this is to separate the silver from the gold then wash it again with water, the color is white due to silver, do this 2 to 3 times until the water is clear. Then Put nitric acid again. repeat this procedure 3 to 4 times until the remaining powder is dark reddish brown. Metallized the powder.The resulting gold is higher than 99.2%, Usually its 99.80%

Mark Yap [returning]
- Cebu, Philippines

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2006

Hi, first I must answer Mr.Yogesh sony from India,
Sir if you are refining with Nitric acid then you are also losing a lot of gold to nitric acid,contrary to the belief that HNO3 does not dissolve gold it does up to an extent.They are using the same process In Amritsar too.also with this process you will not be able to get rid of the Platinum Group of metals,Palladium will be dissolved in Nitric acid and will be lost if you do not recover it.Make sure you use dilute HNO3 about [20%]and at the end of process after removing the precipitate you boil the remaining liquid with copper plate hung inside this will precipitate Silver Palladium and the little gold that was inside the solution. I am from India too but living in Canada.Thanks
Now to mr Mark yap.
Sir you can refine silver almost to 100% purity in the following way.this process is called Mobious Process. You have to make a Electro plating bath .Say you bath has a capacity of 10 liters then you must add 600 grams of silver nitrate crystals and 200 to 300 grams of copper nitrate ⇦ this on eBay or Amazon [affil links] crystals.Rest is Distilled water.The Anode is made in a taper mass of impure silver bullion.Cathode can be a plate of stainless steel Maintain a current of about 40 to 50 Amps per square foot and in order to do that you will need a voltage of 2.5 to 3 volts depending on your local Temperature .The cell ideally should be Maintained at 22 to 25 °C.Thanks I hope it helps you.
and now Wohwill process.
Make a bath about 1.5 liter capacity into that 100 grams of Gold chloride crystals and 150 ml of hydrochloric acid add 1 liter of distilled water and maintain the bath temperature at 65 to 70 °C that will be about 160 degree F. Anode is made from at lest 96% gold and cathode could be pure gold foil or Strong stainless steel plate.The voltage you need is 1.5 volts.you must have ventilation and strict temperature control.Thanks I hope it serve your need.

Opinder Singh
machine builders - Windsor, Ontario, Canada

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2007

How to recover gold from my bath?

Hi dear everyone,
I found this website recently while surfing web. I found you people great. Keep this good work.

I have a problem with my finishing electroplating bath. I will appreciate if somebody helps me.

The bath contains:
dissolved gold in Aqua Regia
Potassium carbonate and di-phosphate
cyanide and water

After a few times of coating the bath becomes dirty and the quality of the coating deteriorates.
I know that there is still some gold in my bath...How can I precipitate and recover it?

Many Thanks in advance
Mehdi

Mehdi Izadbakhsh
hobbyist - Tehran, Iran

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2007

Mr. Vins said: "book by George Gajda . . . but I don't know if it is still in print. The other alternative to books is finding someone who has really done it. I can help with electrolytic silver refining"

Can high grade silver ore be electrolytically processed?

What are the needed chemicals?

Thanks for any help you can offer!~

Charles Olson, D.C.
Hobbyist - Davao, Mindanao, Philippines

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Although those books are not in print anymore, that does not mean they are actually unavailable, Charles. We've included the ISBN numbers for your library to look for them, or you can buy then from Amazon. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

Electrorefining is very time consuming process instead if Aqua Regia process if one does with control can deliver up to 99.99% purity.

Dilip Telang
- Mumbai, Maharashtra, India
March 6, 2008

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April 8, 2008

Hello,
I live here at the ring of fire (Indonesia) with a lot of metals in most of the island.Unfortunately, the extraction of Ag, Au, Pt etc is restricted when it comes to further removing the precious metal (about 30-35%) from the leachings of mercury, cyanide, Iodine etc. Due to the lack of knowledge and high tech explanation from Dr's & PhD's.
By this I mean, I have purchased 3 self-made assembly drawing for a Wholwill-cell, Thum-cell & Electronic sluice. I believe that partly combined, one of them will extract the PM as promised. Except, now it comes to the technical part:
The author mentioned: that a Cu bar, then an Ag, then an Au bar be placed into an Anode Bag. As he talks about an impure gold bar(or multiple bars)which stacked underneath the Anode which sits in a canvas bag.
How does he expect anyone to find so much starter gold, even if it will later be collected again.
Is there anybody who clearly can explain the process? Perhaps with a schematic drawing.
Also as how to collect and monitor the metal at the end of the electrolyte and then burn the same with what chemicals for an ingot mold as a final product.
I thank anybody in advance for the expected information and I hope to be able later to help others.

Best Regards,

George Pawelzick
Mechanical Engineer - Batu, Jatim, INDONESIA

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Sir
I am recovering gold from polish dust through aqua regia (nitric+HCl)but the recovery is not 100%.First I burn dust to ash & then put in acid solution.Then I neutral solution using urea for precipitation gold reagent is used (I don't know the name of gold reagent can you let me know)last step is to filter.
Is this process is right.
Kindly guide me.
Thanks,

DEEPAK DOSHI
JEWELLERY MANUFACTURE - UDAIPUR, RAJASTHAN, INDIA
May 20, 2008

Only physical purification can achieve more than 99.9999% and not chemical processing. Like silicon crystal purification for semiconductors, like crystal pulling in croscalsky process or crystal growing. Gold raw melted and pulled up with pure gold crystal seed, any operation parameter very critical like gradient temperature and speed of pulling, and be sure of freedom from vibration; thus parameter would do with computer.

Abdullah Makky
- Gresik, Jawatimur, Indonesia
June 2, 2008

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I wanted to know the percentage of copper and form of copper available after gold refining. Are there any equipments or companies manufacturing such recovery units.
I see gold refineries here refine 2500 kg/day of gold and realize the valuable copper being wasted. Recovery of copper along with some copper and silver is what I am interested in.

Jigar Dabhi
hobbyist - Satwa, Dubai, UAE
June 28, 2008

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Dear Sir, I have some Au, PGM and Ag concentrate sponge that is well mixed. I really need to know how to part all of them. I have heard that selective voltage electroplating can part the PGM's and Au, but I do not know how at present.
Sincerely, Robert

Robert Shrewsbury
- Manti, Utah
September 20, 2008

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April 27, 2009

Great day to everybody!

My name is Nathan from the Philippines. I've been finding people to help me how can I process my "gold ores" into a real gold? I have no idea what are those chemicals I found in books and in the net that tell chemical names. Can somebody provide me what are the equivalent sample of those?

Hey, Sir Mark! Can you please help me provide a list of stores or suppliers of those chemical compounds, near in Southern Tagalog Region?

Nathan

Nathan Daluz
purchasing - San Pablo City, Philippines

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Ed. note: We believe this website is a great place for technical information, but we have found it to be a poor place for testimonials and supplier recommendations because of the anonymity of the internet. When questions like Nathan's are posed, we can usually count on shills to pose as satisfied customers and glowingly recommend their own company :-)

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June 8, 2009

"How to recover gold from my bath? . . ."

HI MEHDI

THIS IS VINAYKUMAR

THIS REFERS TO YOUR QUESTIONS OF GOLD PLATING DETERIORATES

STEP BY STEP FOLLOW THE PROCEDURE

1. THE PRODUCT SURFACE SHOULD BE POLISHED WITH VERY HIGH FINISH WITH ANY SURFACE WAVINESS AND ROUGHNESS
2.THE PRODUCT SHOULD BE FREE OF CONTAMINATIONS LIKE OIL GREASE ETC, SO THE SURFACE SHOULD BE CLEANED WITH ULTRASONIC CLEANING - DILUTED SUL. DIPPING - STEAMING
3. YOU SHOULD HAVE THE FOLLOWING FLASKS

A) 1 BEAKER FLASKS OF DIS. WATER FOR RINSING
B) 1 BEAKER OF ELECTROCLEANING SOLUTION
C) 1 BEAKER OF DIST.WATER AGAIN
D) 1 BEAKER OF SIT. WATER AGAIN FOR COMPLETE CLEANING
D) 1 AGAIN BEAKER TO RINSING IN DIS.WATER
E) 1 BEAKER OF DILUTED SUL. DIPPING
F) 1 BEAKER OF GOLD PLATING SOLUTION
G) 1 BEAKER AGAIN RINSING

THIS WAY THE MORE CLEANING WILL REDUCE THE CONTAMINATION IN THE GOLD BATH

THANKS

VINAYKUMAR KANCHAGAR
MACHINERY AND EQUIPMENTS - MUMBAI -MAHARASHTRA - INDIA

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Hello;
Gold refining machines are much more effective and ecological way to refine gold, silver, platinum and palladium. You can produce 99.99% pure precious metals in this way. This machines uses nitric acid so well but creates no waste, smell or smoke. They can be installed with any desired capacity.

Mehmet Akidil
- Turkey
June 22, 2009

Hi. I've just started to recover gold from computers phones, etc. Can someone please tell me how to turn the powder back to gold? Thanks.

Phil Davies
hobbyist - uk
March 18, 2010

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I noticed that my initial response on this topic has no date. I suspect that it is nearly 15 or 20 years old! I got out of the electroplating and refining business over five years ago. I currently teach high school chemistry and other science subjects.

Because the refining of precious metals requires hazardous chemicals and I cannot evaluate your training, experience, and environmental awareness, I cannot provide instruction on those processes. I did write a short book a few years back, but never published it. It doesn't provide complete details, only an outline of the processes. If there is enough interest, I might be willing to update the book and make it available.

Bill Vins
- Mesa, Arizona, USA
September 12, 2010

my name is floyd parker I need to know what kind of chemicals to use & how to mix them for electrorefining. I have been trying to use aqua regia to drop out g-s-p-p and haven't had any luck latlyy, have got it out before but doesn't seem to work anymore; have they changed anything lately, have never been able to get any platinum metals dropped out at all please help. floyd

floyd parker
hobbyist - kannapolis, North Carolina
August 23, 2011

Can everybody tell me the example sources for hidden and apparent gold from e-waste?..

Fida Student
- MALAYSIA
November 1, 2011