# Silver cyanide reduction



## Helian (Mar 5, 2009)

Does anyone have any non-life threatening suggestions for refining silver cyanide? I suppose I could dissolve it in sodium cyanide solution, and then drop it with zinc, but would like to come up with something a little more elegant than that.


----------



## goldsilverpro (Mar 5, 2009)

Are you sure you have silver cyanide or do you have sodium silver cyanide or potassium silver cyanide. The last 2 are commonly used in plating baths and will dissolve in water and then it can be zinced out.. Silver cyanide is also used in plating but is not as common. Silver cyanide is soluble in NaCN or KCN, ammonia, or sodium thiosulfate.

If you have silver cyanide, and if you have cyanide available, I would dissolve it and drop it out with zinc.

Any method you use will be dangerous because of the presence of cyanide in the silver cyanide. Make sure you have a good fume hood.


----------



## Helian (Mar 6, 2009)

Thanks! I think I'll set it aside and work through the rest of the stuff I have lying around first.


----------



## Juan Manuel Arcos Frank (Mar 7, 2009)

Helian:

Working with cyanide solutions represents a risk,for you,your neighborhood and the environment.

Before using cyanide try to read the Cyanide Code,it is in the "Books Section" and the wastes treatment of cyanide solutions that GSP had posted here in the Forum.

Be careful.

Manuel


----------



## goldsilverpro (Mar 9, 2009)

> Working with cyanide solutions represents a risk,for you,your neighborhood and the environment.
> 
> Before using cyanide try to read the Cyanide Code,it is in the "Books Section" and the wastes treatment of cyanide solutions that GSP had posted here in the Forum.



I could rewrite that as:

Working with *ACID* solutions represents a risk,for you,your neighborhood and the environment.

If you have a complete understanding of the dangers of cyanide and how to safely work with it, it is far less dangerous than working with, e.g., aqua regia. With cyanide, there are no fumes, to speak of. If you get it on your skin, wash it off. You can destroy cyanide.

I spent about 10 years in the plating industry during the 60s and early 70s, in L.A. I was a plating troubleshooter and spent most of my time in plating shops. There were 100s of plating shops in L.A. at that time. Cyanide was the mainstay of the plating industry. It was used for everything. Cu, Zn, Cd, Ag, and Au were mostly plated from cyanide solution. The best steel cleaner in the world is 8 oz/gal sodium cyanide and 10 oz/gal sugar, run at 200F, electrolytically. The average shop had 1000s of gallons of strong, hot cyanide solutions. In some places, 100s of workers worked around this stuff all day long. I don't remember one poisoning or injury. People knew how to work with it. Of course, all the waste and rinsing went down the drain, raw, but I can't recall any complaints from the city or heard about any problems. I think it can kill the bacteria used for water treatment.

I have used cyanide for gold stripping most of my life. It's the perfect chemical for stripping. 

I usually used a cement mixer - OUTSIDE. I put about 1/2 pound (1/2 of a 4" X 6" aluminum scoop) of sodium cyanide in the mixer, followed by about 2 gallons of hot tap water. Then, I added 40 to 50 ml of 30 to 35% H2O2. I added about 5 - 10# (depending on the material), or more, of boards, fingers, pins, or whatever, and let it tumble. I checked it after 2 minutes - the gold was usually all stripped. If it wasn't, I added a little more H2O2. I rinsed it well. I could run as much as 10 drums of gold plated material a day, by myself. This would generate about one or two drums of solution

The liquids were collected in an open top plastic 55 gal. drum and the gold was dropped with zinc dust. The next morning, the solution was siphoned and dipped off. The solids were well rinsed and then, UNDER THE HOOD (there may be traces of cyanide left), nitric acid was added to dissolve the excess zinc. The gold was collected and put into aqua regia.

The cyanide in the solutions was mostly destroyed electrolytically and finished with bleach/NaOH.

Some Rules:

1) Always use excellent exhaust, although there is very little fuming (a little ammonia smell) and it is safer to work around than fumey acids.
2) Keep any acids in another room. Acids and cyanide mixed together produce HCN, the same gas they used in the prison gas chambers. They lowered cyanide eggs into sulfuric acid.
3) Keep it out of your mouth and your eyes and off your skin and clothing, in order of importance. If I remember right, it only takes .003 gms to kill by ingestion. I may be a decimal point off. Whatever, it doesn't take much to kill you. If it gets on your skin, flush with water until it doesn't feel slick anymore.
4) Wear good rubber gloves and a face shield, at the minimum. Cuff the gloves to prevent solution from running off the gloves and onto your arms or clothing. Wash your gloves before removing them. If you get a pin prick in the gloves, get a new pair.
5) When hot, steam carrying some ammonia and a little bit of cyanide comes off the surface. If the skin is constantly exposed to this, it can produce "Cyanide Itch", a rash of little super-itchy blisters. If you get away from the fumes for a few days, it clears up. Don't constantly work over hot solutions.
6) Read the Material Data Sheet on sodium or potassium cyanide.
7) Don't eat, drink, or smoke around cyanide.
8 ) Use common sense. Respect the cyanide.
9) Clean up spills when they happen.
10) Work with a partner present, in case something happens.
11) Cyanide is safe and pleasant to use if you know and follow all of the rules. It's not something to guess about.
12) Adhere to state and federal laws, concerning waste.


----------



## Juan Manuel Arcos Frank (Mar 11, 2009)

GSP,my Dear friend:

Excellent advices!!!!!!!...Thanks,GSP.

Your friend
Manuel


----------



## Helian (Mar 23, 2009)

Thanks, GSP et. al., I very much appreciate the help.


----------

