Question
Explain hydrometallurgy.
Solution
This method is based on the fact that more electropositive metal can displace less electropositive metal from its salt solution. The concentrated ore is bleached with aqueous solution of suitable reagent (NaCN solution of Cl2in the presence of water) to extract the metal salt in complex salts solution in water. The salt solution is then either electrolyzed or precipitated by adding more electropositive metal. This method also known as complex salt formation method.
Ag2S +4NaCN → 2Na[Ag(CN)2] +Na2S
2Na[Ag(CN)2] +Zn → 2Ag +Na2[Zn(CN)4]
