Give a brief account of the following processes as used in extraction of metals:
(a) Smelting
(b) Magnetic separation
Describe Van Arkel method to obtain metals of high purity.
Van arkel developed a method is based on the thermal decomposition and is used for getting pure metal. In this method, the metal is converted into a volatile compound, while impurities remain unaffected during compound formation. The resulting compound is then decomposed to get pure metal. for example this method is used for refining Zirconium or Titanium:
For example
Ti + 2I2 → TiI4(gas) + heat → Ti +2I2
impure compound pure
What do you understand by the following terms: (i) Roasting, (ii) Calcination, (iii) Smelting?
Describe mainly with balanced chemical equations.
(a) Copper from copper pyrites by self reduction.
(b) Zinc from zinc blende by carbon reduction.
(c) Silver from silver glance by cyanide process.
(a) How is aluminium extracted from alumina?
(b) Give balanced equations for the extraction of aluminium from bauxite by electrolysis.
(c) What is the function of cryolite in the extraction of Al from Al2O3.