Destruction of cyanide wastes by any method is clearly a good thing to do before disposal.
Copperas appears to be a common chemical available to refiners, and luckily can also be used as an indicator for the presence of cyanate ions.
This can be used as a cyanide indicator because it reacts in a complex way with cyanates to produce Iron(II,III) hexacyanoferrate(II,III) (a.k.a. Prussian Blue) which is, er, Blue, and even appears Black if the concentration is high enough.
Commercial testing kits are definitely recommended to get an accurate measure of the cyanate ions in your waste. The EPA limit is stated to be 0.2ppm in this reference :-
http://www.freedrinkingwater.com/water-contamination/cyanide-contaminants-removal-water.htm
0.65g of iron(II)sulphate (a.k.a. Copperas) was dissolved in 25ml of distilled water to make a 0.1[M] copperas testing solution (approx 26,000 ppm) and was put into a dropper bottle.
0.82g of potassium hexacyanoferrate(III) (a.k.a. Potassium ferricyanide) was dissolved in 25ml of distilled water to make a 0.1[M] cyanate solution, which is approx 33,000ppm
This cyanate solution was diluted down in a binary fashion, halving the concentration each time.
Three drops of each concentration from 33,0001 to 2ppm was put into a labelled well on a reaction plate, and one drop of the testing solution was added.
The blue colour appeared instantly on addition of the copperas testing solution and did not change over time.
Given the extremly low 0.2ppm permissible limit, this test can only be used as a 'No-Go' test for wastes, as the appearance of any blue at all means that the cyanide concentration is 10x1 the limit.
On the other hand, this test could be of use if a minimum cyanate concentration is required for a process, such as leeching.
Note:-
1 As the prussian blue compound can be written as Fe7(CN)18, it requires 3x K3Fe(CN)6, so the ppm values could be out by a factor of three.
Not exactly sure about that (yet) as i'm just an amateur chemist, not a trained pro.
Copperas appears to be a common chemical available to refiners, and luckily can also be used as an indicator for the presence of cyanate ions.
This can be used as a cyanide indicator because it reacts in a complex way with cyanates to produce Iron(II,III) hexacyanoferrate(II,III) (a.k.a. Prussian Blue) which is, er, Blue, and even appears Black if the concentration is high enough.
Commercial testing kits are definitely recommended to get an accurate measure of the cyanate ions in your waste. The EPA limit is stated to be 0.2ppm in this reference :-
http://www.freedrinkingwater.com/water-contamination/cyanide-contaminants-removal-water.htm
0.65g of iron(II)sulphate (a.k.a. Copperas) was dissolved in 25ml of distilled water to make a 0.1[M] copperas testing solution (approx 26,000 ppm) and was put into a dropper bottle.
0.82g of potassium hexacyanoferrate(III) (a.k.a. Potassium ferricyanide) was dissolved in 25ml of distilled water to make a 0.1[M] cyanate solution, which is approx 33,000ppm
This cyanate solution was diluted down in a binary fashion, halving the concentration each time.
Three drops of each concentration from 33,0001 to 2ppm was put into a labelled well on a reaction plate, and one drop of the testing solution was added.
The blue colour appeared instantly on addition of the copperas testing solution and did not change over time.
Given the extremly low 0.2ppm permissible limit, this test can only be used as a 'No-Go' test for wastes, as the appearance of any blue at all means that the cyanide concentration is 10x1 the limit.
On the other hand, this test could be of use if a minimum cyanate concentration is required for a process, such as leeching.
Note:-
1 As the prussian blue compound can be written as Fe7(CN)18, it requires 3x K3Fe(CN)6, so the ppm values could be out by a factor of three.
Not exactly sure about that (yet) as i'm just an amateur chemist, not a trained pro.