METALLURGY

Metallurgy The extraction of metals from their ores and refining it is known as metallurgy

ENRICHMENT OF ORE Process used for removal of the “GANGUE” GANGUE – Soil, Sand and Earthy Impurities

Enrichment processes Hydraulic washing

Froth Floatation

Electromagnetic separation

Chemical Method Dissolve ore + Hot and Conc. NaOH Al 2 O 3 + 2NaOH -> 2NaAlO 2 +H 2 O Filter it-  add dil HCl NaAlO 2 + 2H 2 O + HCl -  Al(OH) 3 + NaCl Filter the ppt wash,dry and Ignite 2Al(OH) 3 -  Al 2 O 3 + 3H 2 O Pure Bauxite is obtained

REDUCTION Conversion of concentrated ore into a more suitable form Roasting --  Heating the Sulphide ore in presence of air to form an Oxide ore 2ZnS+3O 2  2ZnO + 2SO 2 Calcination --  Heating the Carbonate ore in the absence of air to form an Oxide ore ZnCO 3 -  ZnO + CO 2

Reduction Low in the reactivity series ----  Heating ----  e.g..2HgS + 3O 2  2HgO +2SO 2 2HgO (S) -  2Hg + O 2 (g) Middle in the reactivity series Heating with C (Smelting) ZnO + C --  Zn + CO High up in the reactivity series  Electrolytic reduction

REFINING LIQUATION: Used for metals having low M.P.  Pb,Sn Metal (low M.P.) Impurity(High M.p.) Hearth

REFINING DISTILLATION Metals used are Volatile -  Hg,Zn The impure metal is heated in a retort. The Pure metal distils over and is condensed in a receiver. The impurities are left behind in the retort

k ELECTROLYTIC REFINING Metals used are ---  Cu,Zn,Sn,Ni,Ag,Au… CuSO 4 + H 2 SO 4