# Cyanide



## Irons (Dec 31, 2007)

In most juristdictions, the use of Cyanide is tightly controlled and permits are required to use it. Just getting it can be problematic and can get you some unwelcome attention.

The use of it has been mentioned on this board a number of times.

Cyanide, if used properly is safe. It's very toxic, but not as bad as H2S. If you do get exposed to it, if it doesn't kill you, there's usually no lasting effect, unless the dose is high enough to cause brain damage similar to what Carbon Monoxide does. It does not build up in the body like Arsenic does.

I explored the problems a number of years ago and spoke with the manager of a waste treatment plant on the subject. It turns out that only a few parts per Million of Cyanide in wastewater will kill the bacteria in the digestion tanks. This causes big problems as you can well imagine. A tiny quantity in a private septic system will do the same. This could get very expensive when things begin to overflow and guess who is going to pick up the tab?

Use some common sense.


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## Lou (Dec 31, 2007)

Yeah, this is true. Nowadays there's Right-to-know laws and various environmental considerations. 

Cyanide ion is very easy to oxidize to cyanate, which is not problematic and is safe(r) to flush down the drain. All it takes is Chlorox, which is basic, which is safe. Makes a little bit of heat. This completely destroys free cyanide.


Lou


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## Irons (Dec 31, 2007)

If I remember correctly, Ferrous Sulfate reacts with Cyanide to form the Ferrocyanate. Harold would recognize the color. It's the deep blue machinists' blue. It's a very sensitive test.
You can buy test strips but most have some Ferrous Sulfate about, and can make their own for almost nothing but a little time.

The reference on edit:

http://en.wikipedia.org/wiki/Chemical_test_for_cyanide

Prussian blue

The formation of Prussian blue can be used as a test for inorganic cyanide, for instance in the sodium fusion test. Typically, iron(II) sulfate is added to a solution suspected of containing cyanide, such as the filtrate from the sodium fusion test. The resulting mixture is acidified with mineral acid. The formation of Prussian blue is a positive result for cyanide.


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## gotgoldfever (Mar 3, 2008)

I have been trying to figure out the best way to extract fine gold from black sand and roasted sulphide concentrates I have left over from dredging placer deposits. I have messed a bit with halide leaching with Sodium Hypochlorite with some success but it doesn't seem to be very efficient. I found this formula for Sodium Cyanide and was wondering if this looks right:

The Bucher Process for the Preparation of Sodium Cyanide:
To prepare sodium cyanide, simply heat 5.41 grams of sodium carbonate [Na2CO3] with 2.45 grams of powdered charcoal or lampblack [C] with 4 grams or so of iron filings [Fe] in a stream of nitrogen [N] (air, being 78% nitrogen, will suffice). The chemical reaction of the Bucher Process is as follows:
The iron is merely a catalyst which is neither changed nor consumed in the reaction which it facilitates. According to Kingzett’s Chemical Encyclopædia, in commercial production a stream of nitrogen is introduced to the reaction vessel under 15 p.s.i. of pressure and the catalyst indicated for the reaction is ferric oxide [Fe2O3] in admixture with an alkaline halide such as sodium fluoride [NaF] , although Sneed and Maynard (in the book, General Inorganic Chemistry) indicate merely that iron is used as the catalyst and that the nitrogen of the air is utilized. Note that a substantial amount of carbon monoxide is produced in the course of the chemical reaction, and so the process might
best be carried out with adequate ventilation. The weights given below the formula above are the gram-molecular weights for the reaction, but the quantities given in the text above the formula are proportionately reduced to yield about 5 grams of sodium cyanide.


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## Lou (Mar 3, 2008)

Erm, that reaction is not as easy as it looks. You have to be somewhat industrious to do it safely and even more so (well equipped reagent-wise) to isolate it.


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## gotgoldfever (Mar 3, 2008)

wow found this thread at the url in your signature:

https://www.sciencemadness.org/talk/viewthread.php?tid=23#pid79894


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## Lou (Mar 4, 2008)

I was about to mention that I know people who have tried it with varying degrees of success.


Read up in that thread (and others there) and you will find that there are many routes to Na/KCN but that not all of them are created equally.


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