sulphur and its occurence and extraction process

1. Sulphur
Occurrence:
Sulphur occurs in nature in free and combined
states. In the free state, it mainly occurs near volcanic regions of
the earth. Free Sulphur is usually found near the earth’s surface
at about 700-900 feet below
Sulphur in combined state is found in nature as:
Iron pyrites FeS
Copper Pyrites Cu2S.FeS
Galena PbS
Cinnabar HgS
Orpiment As2S3
Gypsum ( CaSO4.H
Extraction Of Sulphur
Sulphur is being extracted by different methods which depends
upon the source. The Following methods are more common.
1.Frasch Method:
This process is used for getting
Sulphur from the underground. A hole is drilled through
which four concentric pipes are passed up to the Sulphur-

2. being bed. The innermost pipe is use to compress air and
pipe next to it is used to pass steam which melts the
Sulphur under the earth. Molten Sulphur and its emulsion
with water flow out of the third pipe (from inside). The
outermost pipe allows the unused steam to be removed.
The emulsified Sulphur is transferred to large settling track
where it solidifies on cooling. This process gives about
99% pure Sulphur which can directly be used without
further purification.

3. 2.Sicilian Process:
In Sicily, Sulphur is found mixed with
gypsum and quartz. The lumps of ore in the form of leap are
heated in closed chamber. Sulphur melts and is collected from
the base of the chamber.
The Sulphur thus obtained is further refined in closed iron
retorts and Sulphur vapors are collected in large chambers to get
flowers of Sulphur. This is melted to get brimstone
3.From Sulphides and Sulphide Ores:
The Sulphide
ores are usually treated to extract metals, and SO2 is obtained as
a result of roasting during this process. Sometimes, it become
necessary to reduce SO2 to Sulphur.
SO2 + C → S + CO2
The overall process starting from CaS is:
CaS + H2O + CO2 → CaCO3 + H2S
2H2S + O2 → 2S + 2H2O

4. 4.From Coal Gas:
Coal gas contains H2S which is
removed by passing the gas over heated Fe2O3 to get Fe2S3 and
FeS. The mixture is known as spent oxide. When Fe2S3 and FeS
mixture is allowed to remain in contact with water and air to
undergo weathering, Sulphur is deposited.
Fe2O3 + 3H2S → Fe2S3 + 3H2O
2 Fe2S3 + 3O2 → 2Fe2O3 + 2H2O + 6S
5. By Bacterial Action:
Certain Bcateria have remarkable
ability to convert sulphates into free Sulphur. Artificially
prepared strains of Bacteria have been used to prepare Sulphur
from calcium sulphate.