Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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How to make potassium gold cyanide
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A. Focusing on Potassium Gold Cyanide (PGC) uses first. There are important risks and these risks cannot be managed by an untrained person (even a chemist).
1) PGC is used mainly to prepare Gold Plate Baths. It has little value if you don't know how to use it properly. Most probably the readers of this article want to do this, but it involves a lot more questions.
2) Even the production process of GPC or electrolytic Gold Baths involves money, and of course the people who really know good formulas and chemistry process spent a lot of money to develop, test, and do the maintenance of the baths from time to time (this is my case). I am Chemist Engr. and I have read a lot of books, patents and articles, together with my background of chemist. I produce jewelry with around 30 milligrams/ gram of silver (but it can be more), and I sell the items and study the returns in warranty, so I adjusted a lot my decisions, and now is stabilized; I started with 24K gold layer and now it is around 19K (alloyed, so other metals are added, in jewelry it very important because of wear resistance and color/ shine).
3) I and the others who know a good way -- there are plenty of them -- to convert all of this into money will not teach for free, we cannot do this (please understand we cannot give for free the only thing we have to sell).
4) So, there is another problem: some countries do not let people buy some reagents (this must be checked prior) here in Brazil, for example, is impossible to buy KCN.
5) If this is your case, to convert PGC into money, especially by selling jewelry you can propose to buy the knowledge from someone, but have in mind that there are costs involved as: gold 24k, reagents, equipment , proper place, utensils, and costs with safety, Also specialized chemist training (it is necessary, believe me).
- São Paulo, SP - Brazil
November 14, 2022
P.S. I will not answer students, masters, or doctors which purpose is research.
Ed. note: Thanks for your very well-expressed points, Otacio!
But your point '3)' goes both ways: so apologies, but just as you can't help people unless they pay for your services, we can't help consultants privately hook up with clients for assignments unless they advertise here.
⇩ Related postings, oldest first ⇩
Q. I am conducting a feasibility study on the production of potassium gold cyanide. I need information about the ff:
a. how to produce potassium gold cyanide
b. uses of potassium gold cyanide
c. cost per gram
Thank you very much.
Concepcion S. VillaverdeMetals Industry R&D Center - Gen. Santos Ave. Bicutan, Taguig, Metro Manila
1998
A. I had the same question about this topic a few months ago. I haven't got a complete book or literature that explains producing PGC. However through some experiment with limited literature I produced PGC. The quality of PGC (percentage and purity) is still not known yet, but I have used for several months in my gold plating bath without a problem.
Next is how I make PGC:
1. Make aqua regia (75% HCl + 25% HNO3) from high grade chemical.
2. Introduce the Gold (24 kt) in bulk or small piece in warm aqua regia for fast solubility. (gold : aqua regia is about 1 : 5 weight).
3. Heat the solution, don't exceed 85 °C.
4. A long heating introduces excess HCl.
5. Heat and evaporate until you've got a concentrate like syrup that is Gold Chloride.
6. Gold chloride will become crystals when you cool the syrup.
7. Introduce a little water to dissolve the gold chloride.
8. Make ammonia ⇦this on eBay or Amazon [affil links] solution of 30 ml ammonia in 100 ml water concentration. (use high grade ammonia).
9. Pour the ammonia slowly to Gold Chloride until pH = 8. You will get the precipitate that call Gold Fulminate. Be careful with the Fulminate, It should not be allowed to dry because it is Highly Explosive! Danger!
10. Wash the Precipitate to remove excess ammonia. Wash several times until pH reaches near 7.
11. Make another concentrated Potassium Cyanide solution (KCN).
12. Pour the KCN into Fulminating Gold slowly with agitation until all the fulminate dissolves. You've got a solution called "Mother Liquor".
13. Heat the Mother Liquor -- in my experience not over 65 °C. Evaporate ammonia from mother liquor until no ammonia smell anymore.
14. Crystallize the PGC by continued evaporation. Vacuum will be very helpful. You don't need to evaporate all the mother liquor. When you've evaporated about 75% volume, stop the process. Collect the PGC and keep the mother liquor. Dry the PGC by vacuum. Mother liquor still can be used in the next production by mixed it with the next Fulminate.
15. Do all the processes in very good ventilation. Good luck.
Any ideas and corrections regarding my process will be welcome.
Anton Bijosono- PT.CITRA SELARAS HARMONI - INDONESIA
Wow! The detail of the response to the PGC question was incredible. Thanks to you, Anton.
Now everyone knows why it pays to buy your gold salts ready made in precisely weighed quantities. I would not take the chance of making one mistake and ruining the batch, even with the price of gold as low as it is. I prefer to let the refiners at Technic, LeaRonal, and the rest of them worry about the QC. And the technical advice from those vendors on how to run the plating bath isn't half bad either.
Bill Vins
microwave & cable assemblies - Mesa (what a place-a), Arizona
!! When making PGC, the fulminate-mother liquor steps you should use ammonium OXALATE instead of ammonia. The gold-nitrogen bond(s) formed by using ammonia become a heat-, friction- and impact-sensitive explosive when dry, similar to the related mercury and silver compounds.
Steve Koelzer- Sunnyvale, California USA
2003
Q. Dear Anton
Thanks for posting very clear process, but this process is very classical,
Some demerits are as below:
1.low yield
2. more handling
3. fulminating gold is very explosive
4. requires very skilled chemist
5. cannot be commercially viable
Due to above, there is a new technology "Electrochemical dissolution of gold in KCN solution in cationic diaphragm cell"
I seek this technical know how.
Regards
- Indore, India
July 29, 2023
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Q. re: Anton Bijono potassium cyanide production. The gold cyanide produced by your method does not work well with our plating formulation; could you provide us with your gold plating recipe for trial? Many thanks. Claude HudonPlating shop - Gatineau, Quebec, Canada 2004 |
Multiple threads merged: please forgive chronology errors :-)
Q. Could anyone please tell me the type of Potassium Cyanide used in casting gold and plating, 151-50-8 and 554-07-4. Also what type of Nickel sulphate is best used. What is the best source for these in the US?
Torry Mathews- Ohio
1998
A. Hi Torry. I'm not familiar with the digits you've provided for potassium cyanide (they just look like catalog numbers to me), but the short answer is that in the U.S. you can buy such supplies from the distributors of plating supplies, and that you can usually find them listed under Plating Supplies in your Yellow Pages, or in our Directory of Chemicals, the Metal Finishing Guidebook, or the Products Finishing Directory. Good luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I want to know more in detail about the potassium gold cyanide or gold cyanide. Please do reply to me and tell me what are the steps involved and what kind of stuff I will need to get this done. Thank you very much.
Mark [last name deleted for privacy by Editor]BLACK KNIGHTS - Malaysia
1999
Ed. note: Since 1989 this forum has enjoyed the camaraderie & warm aloha which real names & locations afford. If you're not into that spirit, those who do post with their real name may be less likely to engage with you.
(starting over can be the kiss of death to a thread)
Hi Mark. Anton provided an incredible depth of detail (and there has been additional helpful followup too).
Please try your hardest to frame your questions in terms of what has already been said, what parts you understood, and what parts are still unclear to you, etc. Thanks!
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Seeking process equipment to make Gold Potassium Cyanide
RFQ: Seeking for process equipment to make Gold Potassium Cyanide.
Kao, AndrewHong Kong
2002
Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)
RFQ: I want to know if there is any equipment available in market for extracting gold from ore using cyanide process.
Ali Marzouqi- accra, Ghana
February 15, 2009
Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)
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That certainly shines a different light on "take time to smell the flowers" :-)
Q. I'm having a project and I have thought about how to make ammonia out of flowers. Student - Dhahran, Kingdom of Saudi Arabia 2000 |
Q. Dear All,
I am a master student and my project is about potassium gold cyanide and I need to have more information if you advise some web site, book or any search about that I will appreciate.
Thanks,
Nuket Cakit- Istanbul, TURKEY
2002
by Reid & Goldie
(hard to find & expensive; if you
see a copy cheap, act fast)
on eBay or
AbeBooks
or Amazon
(affil links)
Hi Nuket. This website has dozens of threads about potassium gold cyanide, please search the site with the term "gold cyanide". This book about gold plating ⇨ references potassium gold cyanide hundreds of times.
Luck and Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I'm studying Potassium gold cyanide too. There are two ways: chemical and electronic. The chemical way uses potassium cyanide solution gold directly; I've read it in lots of books, but its rate is too slow. I don't know the reason. Do you know the way it should be done?
Moreover, my electronic way is already finished but the product has color. I don't know the reason. Who can tell me?
Thanks very much.
ZhouweiIPM - China
2002
Ed. note: Since 1989 this forum has enjoyed the camaraderie & warm aloha which real names & locations afford. If you're not into that spirit, those who do post with their real name may be less likely to engage with you.
A. KAu(CN)2 can be made very efficiently and pure by the anodic dissolution of metallic gold in a KCN solution. A membrane separates the cathode to prevent cathodic plating of the dissolved gold.
If the process is run hot, very pure KAu(CN)2 precipitates on cooling. The mother liquor, after replenishing with KCN, is used for the next batch.
- Rockland, Delaware, USA
2007
Q. Dear Walther, we want to know more about anodic dissolution of gold in KCN solution.
RFQ: From where we get this instrument (diaphragm cell)?
Regards
- india indore
July 11, 2023
privately respond to this RFQ
Ed. note: As always, gentle readers: technical replies in public and commercial replies in private please (huh? why?)
Q. Good night!
In first place I want to beg your pardon for the grammar mistakes, because I am writing with an electronic translator's help. I would like to know as I do to get information of the process of obtaining of the salt of gold (GPC). This process is little known in my country and consequently there is not any literature on the same.
Certain of your attention.
Marivaldo XavierStudent - Manaus, Amazonas, Brasil
2003
Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)
Q. I want to know the procedure for making gold potassium cyanide (gpc). What chemicals are used in preparation and in what quantity, temperature. Full information about gpc from start till end. Please tell me.
Siddharth- Varanasi, UP & India
2003
Q. What is best procedure for make PGC and what's the effect of PGC on human body
Mohand Saed- Sudan
December 27, 2008
Q. Sir,
can you help me to prepare the gold bath using the g.p.c, I would like to know the formulation and different types / method available for different shades.
Thanking you,
Nagesh
- MYSORE, India
December 21, 2010
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Q. So what would happen if you mix HCl with potassium ferrocyanite? Paul Anthony- Syracuse New York United States October 1, 2011 !! Hi, Paul. Please try to put your question in context. Are you looking for the formula for the reaction ... or maybe the stoichiometric relationship? Do you mean is it a good way to make Prussian Blue? Are you asking whether it will explode? Or be poisonous? Or release gasses? Please get back to us with your situation, but also double check that you mean ferro-cyanite not -cyanide or -cyanate -- there may be such a thing but I've personally never heard of it. Thanks & regards, Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey |
by Reid & Goldie
(hard to find & expensive; if you
see a copy cheap, act fast)
on eBay or
AbeBooks
or Amazon
(affil links)
Q. From where we can get book "Gold Plating Technology", by Reid & Goldie?
ANILindore, India
November 8, 2011
Ed. note: Since 1989 this forum has enjoyed the camaraderie & warm aloha which real names & locations afford. If you're not into that spirit, those who do post with their real name may be less likely to engage with you.
Q. Hi all. Please tell me the procedure to make Gold Potassium Cyanide from gold and amount of chemicals used in each step of reaction. Please tell the secure way to handle the Gold Fulminate and potassium cyanide also.
Manoj Garg- Ganganagar, Rajasthan, India
June 12, 2012
A. Hi Manoj.
We appended your inquiry to a thread that may partially answer it for you. But please remember that the internet is a giant one-room schoolhouse, where grade school children and post doc researchers may read the same page. Readers will frequently read discussions about things that they do not have the experience & training to safely do!
When it comes to the "secure way" to handle gold fulminates and potassium cyanide, the answer is that you absolutely must learn that in a hands-on haz-mat training course, you must never attempt to learn it via a public forum. Sorry! Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I want to set up manufacturing unit of GPC. Please help me with some standard good quality machine manufacturers.
Rohit Agarwal- Hyderabad, India
April 6, 2013
!! Hi Rohit. If any readers offer any manufacturer names, we'll post them here. But testimonials and references to "good quality" aren't compatible with an essentially anonymous public forum. ( huh? why?). Sorry.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I want to know if there is hydrogen cyanide released when pumping air into potassium cyanide solution when gold is being dissolved? Is there hydrogen cyanide released when gold plating if there is still free cyanide in the solution? If gold is dissolved by potassium cyanide solution can the solution be used to gold plate? Does gold have to be electrolysed into the solution or is this an alternative method to a gold plating solution? It's a bit confusing. I have also read that hydrogen peroxide speeds up oxygenation in gold cyanidization -- is there any truth to that? Thank you.
Does the process that Walther Grot describes release dangerous hydrogen cyanide? I have done similar but with cyanate and the results were incredible BUT it rubs off. Yes, it rubs off with ammonia-base Brasso ⇦this on eBay or Amazon [affil links] cleaner.
Dennis Courvier- Detroit, Michigan
July 14, 2013
Q. Dear author
We have done all the steps mentioned above and we reached a yellowish salt and we think that it contains some amounts of chloride. What should we do to reach to PGC?
Can you tell me more about the washing step?
Thank for your help in advance.
Regards
iman
- Tehran, Iran
October 9, 2013
Q. These posts are very helpful for the processes, but I can't find anything about what amount of KCN to water to use for making the solution. Does anyone know?
Eliana Ismé- Amador City, California, USA
November 30, 2013
A. Hello Eliana,
Your question is how much KCN is needed to add to water to make the solution? Or is it potassium gold aurocyanide you are talking about? If it is PGC you are asking about, you can't just add it to water and expect to plate with it. Please be more specific with your question.
Process Engineer - Malone, New York, USA
Q. May I pose an ethical question?
Should we be encouraging people who obviously have no knowledge of even basic chemistry to handle seriously toxic materials? In most parts of the world, cyanides are simply not available to the general public and I know of universities that will not allow degree level students to use it.
Before using cyanides, or any other chemical, you should be able to answer the question - Do I know what to do when (not if) something goes wrong?
With cyanides there may be no second chance. This area should be strictly left to the professionals.
Geoff Smith
Hampshire, England
December 5, 2013
Hi Geoff. We actively discourage amateurs on this and dozens of very similar threads. We remind them that the internet, like a library, is a one-room schoolhouse where they will read about stuff they can't safely do. We suggest books, and we explain the need for hands-on haz-mat training and chemistry knowledge, etc. When they read your response (from someone who is a true cyanide expert), I hope it completely dissuades them! Still, people sometimes cannot be dissuaded.
I think it is an excellent idea to keep telling people "Don't attempt this at home", but I don't find it realistic to believe that erecting a wall of silence will make the world a safer place. If they simply google "how to make cyanide" there are instructions with no warnings at all written by deliberate troublemakers. We have several threads here on "gold recovery" where we are criticized (even by a trained first responder firefighter!) for not providing enough detail to untrained amateurs, because (per their claim) not answering encourages people to experiment with no knowledge instead of with some knowledge. Ya can't win :-)
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. I think cyanides could be handled safely by an informed layman. One just must never, ever, forget what one is dealing with.
Dave Wichern
Consultant - The Bronx, New York
Thanks Dave, but despite my very high opinion of your postings and knowledge, sorry but I will have to respectfully disagree with you this time.
When I taught safety in plating, I would try to draw interest by starting with this question on the blackboard:
"A conscientious person who has been properly trained in safety [will / will not] sometimes do unsafe things?"
It usually took some people in the class a while to get on board with the correct answer, but after discussion and self-examination they realized that people worry about their sick children, they argue with their spouse, they agonize about how to pay the bills, or what to do about their aging mother, or a hundred other things -- we need disciplinary rules for wearing PPE, for not working alone, for ticking the checklist, etc., because someday somehow absolutely everybody "forgets what they are working with".
As an expert witness many times on deaths & maiming in plating shops, I don't like to think about all the people who decided to peek at the process solution in the tank while the programmed crane was "safely" at the other end of the line ... and then their glasses fell in, or they saw a part that fell of the rack, or there was a cigarette butt in the tank -- and tragedy struck when they lost their focus on that still energized crane. In my opinion nobody has the self-discipline to work safely on their own with extremely dangerous materials :-)
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Dear Anton, could you please inform the percentage (ratio) of concentrate KCN solution? How many gram KCN in how many ml water? Thanks.
Can Gokten- Istanbul, TURKEY
September 16, 2014
Q. Hello,
If gold in gold fulminate has a valence state of (+3) how can we obtain the KAu(CN)2 that has a valence state of (+1) how is the reduction process occurs during the dissolution of gold fulminate?
Thank you.
- Istanbul, Turkey
January 4, 2016
Q. We are doing gold recovery process from plating impurity. When we manufactured gold potassium cyanide based on the instruction above, we get salt with good purity. But, the salt becomes yellowish color after 12 hours of storage.
Can you tell us the reason for this and what mistake we would have done, during our manufacturing process?
- Chennai tamilnadu India
August 29, 2016
? Hello, are you using plain ammonia or ammonium oxalate? What is your drying process? Vacuum drying is a necessity.
Mark BakerProcess Engineer - Phoenix Arizona
Preparation/Extraction of Potassium Cyanide
Q. I am a research student and want to extract gold for which I require potassium cyanide. How can I prepare/extract potassium cyanide? From which source will the extraction be fruitful? What is its cost per gram?
Sana Shaikh- Mumbai, Maharashtra, India
December 2, 2017
A. Hi Sana. You should probably buy the potassium cyanide rather than attempting to make it. But check that your research facility permits the making or using of potassium cyanide and that you have the proper safeguards on hand, and have received hands-on haz-mat training first. If you must make it, a google search will instantly reveal a number of troublemaker sites which teach how to make cyanide and even worse poisons at home; you start by making ferrocyanide.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Thank you Chris Owen,
Not only answering my question (on thread 7022,"How to strip plated silver off copper") but giving me some more knowledge about metal recovery.
From what I am gathering by now I think I am in the right company to ask a question which I tried to find answers on the net. Unsuccessful.
I know it takes one gold molecule and two Cyanide molecules to dissolve gold.
How does this equate to weight.
How much weight of cyanide is required to dissolve one troy ounce of gold?
Thank you for your help.
Alfred
- Canberra Australia
December 19, 2017
A. Alfred,
Theoretically, it would take 98.04g of sodium cyanide, NaCN, or 130.22g of potassium cyanide, KCN, to combine with 196.967g of gold to form either NaAu(CN)2 or KAu(CN)2. In practice, since cyanide chemicals are fairly unstable and due to the fact that there are several chemical steps in the process, it will probably take some extra cyanide.
- Benton, Arkansas, USA
A. Hi Alfred
Chris has answered your direct question but don't think that simply adding gold to a cyanide solution will result in potassium gold cyanide.
The actual result is wet, and now toxic, gold.
Gold is extracted from ore with cyanide but it is in a finely divided state and oxygen, usually from air, is needed for any reaction to proceed. Commercial GPC is commonly produced electrolytically.
Your probability of success is low and the probability of losing much of your gold is high, not to mention the hazards of the operation.
Your most profitable, and safest, strategy would be to sell your gold to a supplier of plating salts.
PS Please don't even think of using hydrogen peroxide to provide oxygen to the cyanide. The smallest splash on the skin is incredibly painful. It is the only time I have witnessed pentathol administered for pain -- and it was only partly successful.
Geoff Smith
Hampshire, England
A. Potassium cyanide kill a person.
Simi harkeshSimKnn - Pali ,rajasthan, India
Q. Hi,
We manufacture Gold and Silver plating Chemicals. I want to know how can we remove the chloride content from the final output, or alternately, how do we manufacture chloride free GPC?
- Bangalore, Karnataka, India
February 5, 2018
Q. Dear All,
I have a mixture of Potassium gold(III) cyanide and Potassium Chloride (KAu(CN)4 + KCl).
How can I separate Potassium gold(III) cyanide from Potassium Chloride solution?
- Isfahan, Iran
February 21, 2018
Crystallization is a purification.
Lalit Mohan Agarwal- AGRA, Utter Pradesh India.
September 14, 2022
Q. I have read the entire thread which is highly informative. My question here is.. How to neutralise the yellow Gold precipitate formed during addition of ammonia solution to Aqua regia so that I can smelt it in a furnace to 999% pure gold bar ?
Mustafa KantawalaGolden Touch Electroplating - Surat, Gujarat, India
February 16, 2020
A. Gold fulminate is explosive, never dry or ignite otherwise life will be in danger.
Lalit Mohan Agarwal- AGRA, Utter Pradesh India.
September 14, 2022
Q. Good morning. I have had potassium gold cyanide synthesis through chemical/conventional process, and I got the percentage of PGC around 58 - 61% and surprisingly it can be used for the plating bath. But the problem comes, that the mother liquor turned yellowish when I put the mother liquor for 3 days in an open environment. Could anyone help me to explain about this matter? Thank you!
Octa Tampubolon- Jakarta, Indonesia
May 4, 2020
A. Hello, PGC is normally supplied as 67.5% or 68% gold content per weight. I am not sure what you have there and what chemical process you used to make it.
Mark Baker- Winston Salem, North Carolina USA
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