Thu August 16, 2012 By:

An ore on heating in air produces sulphur dioxide gas.which process would you suggest for its concentration?describe briefly any 2 steps invoved in the convertion of disconcentrated ore into related metal.

Expert Reply
Fri August 17, 2012

The roasting of sulfide ores such as pyrite, sphalerite, and cinnabar (mercury sulfide) releases SO2:

4 FeS2 + 11 O2 ------> 2 Fe2O3 + 8 SO2
2 ZnS + 3 O2 -------> 2 ZnO + 2 SO2
HgS + O2 -------> Hg + SO2
4 FeS + 7O2 -------> 2 Fe2O3 + 4 SO2

Large amount of copper are obtained from copper pyrite (CuFeS2) by smelting. Ores containing 4% or    more copper are treated by smelting process. Very poor ores are treated by hydro-metallurgical process. The two steps invoved in the convertion of disconcentrated ore into related metal:

Smelting : The roasted ore is mixed with coke and silica (sand) SiO2 and is introduced in to a blast furnace. The hot    air is blasted and FeO is converted in to ferrous silicate (FeSiO3).
FeO + SiO2 è FeSiO3 
Cu2O + FeS è Cu2S + FeO
   FeSiO3 (slag) floats over the molten matte of copper.
BESSEMERIZATION  Copper metal is extracted from molten matte through bessemerization . The matte is introduced in to    Bessemer converter which uphold by tuyers. The air is blown through the molten matte. Blast of air    converts Cu2S partly into Cu2O which reacts with remaining Cu2S to give molten copper.
2Cu2S + 3O2 è 2Cu2O + 2SO2 
2Cu2O + Cu2Sè 6Cu + SO2

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