[Vo]: Re: What is HTP ?

[Frederick Sparber]

Since Jones is smitten with HTP/Gold Fever.  :-)

 

Heap Leach extraction of gold from ore requires aeration (spray)

of the water-cyanide leachant to form H2O2.

 

Similar  Anodic and Cathodic reactions can occur in an electrolysis cell

without the cyanide,but, possibly enhanced by dissolved metal (M +) ions.

 

http://www.metlabsolutions.com/business.html

 

A

Let's explore exactly how cyanide dissolves gold:

The cyanidation process of metals is a heterogeneous reaction (i.e. a reaction driven by unrelated or unlike components) and is a corrosion process.

The reaction for this process is: 2 Au + 4 KCN + O₂ + 2 H₂O ===> 2 KAu (CN)₂ + 2 KOH + H₂O₂

The metal in question (Au) dissolves by two processes occurring simultaneously on its surface. At one end of the metal, the cathodic zone, oxygen takes up electrons and undergoes a reduction reaction. At the other end of the metal, the anodic zone, the metal gives up electrons and undergoes an oxidation reaction.  The anodic and cathodic reactions can be expressed as:

Anodic:
(1) Au ===> Au⁺ + e^-
(2) Au⁺ + 2 CN^- ===> Au (CN)₂

 

Cathodic:
(1) O₂ + 2 H₂O + 2 e^- ===> H₂O₂ + 2 OH^-

In an electrolysis cell:

 

At the cathode:

 

Dissolved O2 gas + 2 H2O + 2 e-   ----> H2O2aq + 2 OH-

 

At the Anode 2 OH-   - 2 e-  ----->  H2O2aq

 

Provided that the cell is kept at low temperature.

 

OTOH, the presence of CO2/H2CO3 will provide H+/H3O+ cations and

HCO3- and CO3= anions which will accept electrons at the cathode and

donate electrons at the anode respectively, hence setting up an ancillary CO2-H2O cycle.

 

Fred