The cyanide extraction process (also called Mac-Arthur Forrest process) is used to extract silver from argentite ore (Ag₂S). Let's understand the process step by step:

Step 1: Leaching
The crushed argentite ore is treated with a dilute solution of sodium cyanide (NaCN) in the presence of air. Oxygen from air acts as the oxidizing agent. The silver sulphide is oxidized and forms a soluble complex.

Chemical reaction:
$4\mathrm{Ag}{S}_{\left(s\right)}+8\mathrm{NaCN}+2H_{2}O+O_2\to 4\mathrm{Na}\left[\mathrm{Ag}{\left(\mathrm{CN}\right)}_2\right]+2\mathrm{Na}{S}_{2}O{H}_3$

Step 2: Precipitation
The soluble sodium argentocyanide complex is then treated with zinc dust. Zinc acts as the reducing agent and displaces silver from the complex (since zinc is more reactive than silver).

Chemical reaction:
$2\mathrm{Na}\left[\mathrm{Ag}{\left(\mathrm{CN}\right)}_2\right]+\mathrm{Zn}\to {\mathrm{Na}}_2\left[\mathrm{Zn}{\left(\mathrm{CN}\right)}_4\right]+2\mathrm{Ag}{\left(s\right)}_{\downarrow }$

So, in summary:
- Oxidizing agent: O₂ (oxygen from air)
- Reducing agent: Zn dust

Related Topics:
Hydrometallurgy and Leaching: This process falls under hydrometallurgy where metals are extracted using aqueous solutions. Leaching involves dissolving the metal from ore using a suitable reagent.

Formulae:
The key chemical equations involved are:
1. 4Ag₂S + 8NaCN + 2H₂O + O₂ → 4Na[Ag(CN)₂] + 2Na₂S₂O₃
2. 2Na[Ag(CN)₂] + Zn → Na₂[Zn(CN)₄] + 2Ag↓

Final Answer: O₂ and Zn dust respectively