Question

Explain how silver is extracted from its chief ore.

Answer 1

Extraction of Silver from the Argentite ore. Silver is extracted from the argentite or by the Mac-Arthur and Forrest's cyanide process.
The various steps involved in this process are:
(1) Concentration: Tfe crushed ore is concentrated by froth-floatation process.
(2) Treatement of the ore with $NaCN$: The concentrated ore is treated with $0.4-0.6$% solution of sodium cyanide for several hours. The mixture is continuously agitated by a current of air, so that $Ag$ present in the ore is converted into soluble sodium argento complex.
${Ag}_{2}S+4NaCN\rightleftharpoons 2Na\left[Ag{\left(CN\right)}_2\right]+{Na}_{2}S$
(3) Precipitation of silver: The solution containing Sodium argento cyanide is filtered to remove insoluble impurities and filtrate is treated with zinc dust, silver, gets precipitated
$2Na\left[Ag{\left(CN\right)}_2\right]+Zn⟶{Na}_2\left[Zn{\left(CN\right)}_4\right]+2Ag\downarrow$
(4) Electrolyte refining: The impure silver is further purified by electrolyte refining. The impure silver is made the anode while a thin sheet or pure silver act as the cathode. The electrolyte is silver nitrate acidified with $1$% nitric acid. On passing electricity pure silver gets deposited at the cathode.