Question

How is silver extracted from argentite ore?

Answer 1

Argentite ore is $A{g}_{2}S$. It is leached with dilute NaCN solution in presence of air.
$A{g}_{2}S+2NaCN\to N{a}_{2}S++2AgCN\downarrow$
$AgCN+NaCN\to Na\left[Ag\right(CN{)}_2]$
or
$4Ag+8C{N}^{-}+2H_{2}O+O_2\to \left[Ag\right(CN{)}_2{]}^{-}+4O{H}^{-}$
From soluble complex, silver is displaced by zinc
$2\left[Ag\right(CN{)}_2{]}^{-}+Zn\to \left[Zn\right(CN{)}_4{]}^{2-}+2Ag$
Zinc can displace $Ag$ as $Zn$ is more active than $Ag$.