Thiocyanat-nitrite leaching - safety question

[Stowmaster]

There are data, that gold is dissolved in a mixture of thiocyanate and nitrite.
The end product is a cyanide-gold complex.
Interested in the issue of security of this reaction. I guess the intermediate products and impurities may be hydrogen cyanide and potassium cyanide.
I am Interested professionals opinion on this technology.

Supposed the reactions:
2 KNO2 + KSCN = KCN + N2O + K2SO3
6 KNO2 + 4 KSCN + 2 Au = 2 KAu(CN)2 + 3 N2 + 4 K2SO3
6 KNO2 + 4 KSCN + 2 Au = 2 KAuC2N2 + 3 N2O + K2S + 3 K2SO3
3 KNO2 + 2 KSCN + Au = KAu(CN)2 + 3 NO + K2S + K2SO3

All products are acidic, so guess what the reaction is extremely dangerous.
Cyanide solutions should not be allowed to drop below a pH of 9, for reasons of safety. As you alluded, yes, what you provided is, indeed, extremely dangerous.

What is your objective?

Harold

 

[Stowmaster]

My goal - getting gold from the poor material (approximately 1 g / kg) without dissolving the base metals. Information that the mixture of thiocyanate and nitrite dissolves the gold plating, I found on the russian site.
http://wsyachina.narod.ru/chemistry/gold_2.html
However, the chemical equation I am not found anywhere else. Work with cyanide I do not want, not because of safety, but because of the police and the law question.

There are 3 variants of this reaction.
1) Safety: first formed thiocyanate complex of gold, which is converted to cyanide complex.
2) Dangerous, first produced cyanide, which dissolve the gold.
3) The first and second variants together.

What reaction is done I need to know.

 

[butcher]

I see no hydrogen in the equations above, I do see salts, what makes you think the solution is acidic?
I would think HCN would be a byproduct as a gas in the reaction if acids were involved, I do not see it in what is quoted here.

KNO2 (potassium nitrite), when trying to look up this salt to see if it is even a slightly acidic salt this is what I found:
KNO2 it should be basic, not acidic. The is an example of a salt with a weaker conjugate acid than base. Think of it this way:

KOH is a strong base so it dissociates totally. This means that the potassium in potassium nitrite, when dissociated in water has no potential to sequester any of the hydroxide ions (from dissociated water molecules). In short, it is a spectator (ion) in the system. Yet another way of thinking of this is that potassium is a WEAK CONJUGATE ACID.

HNO2 (Hydrogen nitrite, or nitrous acid when dissolved in water) on the other hand is a weak acid so the hydrogen and nitrite do NOT completely dissociate - the nitrite has the tendency to hold on to some of the available protons (it is a stronger conjugate base than potassium is a conjugate acid). This means that the nitrite in a potassium nitrite solution sequesters some of the protons from dissociated water away leaving unmatched hydroxide ions.

The solution will be basic because of these un-partnered hydroxides.