Electrochemical processes cyanide solutions

Process of cyanide dissolution of gold (gold is not soluble in hot acids) Dissolution of gold in dilute cyanide solutions recognized as electrochemical process... 

Mughogho, D.T. Crundwell, F.K. (1996). Gold dissolution in dilute cyanide solutions. In R. Woods, F.M. Doyle P. Richardson (Eds.), Electrochemistry in mineral and metal processing, IV (pp 275-307). Electrochemical Society Inc. USA,... 

According to Gerischer [136], Zn(OH)2 is the electrochemically active complex that takes place in the charge transfer processes occurring in sufficiently alkaline solutions. This EAC can be formed not only in zincate solutions but in cyanide solutions as well. Similar mechanism was also postulated for Zn(II) reduction in alkaline D-mannitol solutions [134] however, this view seems to be unacceptable for acidic media. It follows from the data obtained at 3.7 < pH < 5 [127] that both Zn " " and ZnE" " might be electrically active. This leaves the question of the EAC structure open. 

The one-electron electrochemical reduction of NP (57) is a reversible process in aqueous solution, provided the measurements are performed at pH > 8 (—0.123 V vs. NHE) (57a,57b). Different chemical reductants such as sodium in liquid ammonia, tetrahydroborate, ascorbic acid, quinol, dithionite, superoxide or thiolates are also known to generate the [Fen(CN)5NO]3 ion (48,57). However, care must be taken in the products analysis, because the negative redox potentials of some of these reductants allow for further nitrosyl reduction (57a). Also, the reduced product is unstable toward cyanide... 

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