General
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Sulphuric acid is clear, colourless or brown oily liquid that is
highly corrosive. Sulphuric acid is made by burning sulphur. The
sulphur dioxide given off is then reacted with a catalyst at high
temperature to give sulphur trioxide. This can then be absorbed to
give the acid. Depending on its intended use, it can be further
diluted with water. This method of manufacture is called the Contact
Process.
- Sulfuric acid is
a corrosive chemical and can severely burn the skin and eyes. It may
cause third degree burns and blindness on contact. Exposure to
sulfuric acid mist can irritate the eyes, nose, throat and lungs, and
at higher levels can cause a buildup of fluid in the lungs .
Asthmatics are particularly sensitive to the pulmonary irritation.
Repeated exposures may cause permanent damage to the lungs and teeth.
The International Agency for Research on Cancer has classified
'occupational exposures to strong-inorganic-acid mists containing
sulfuric acid' as carcinogenic to humans.
Process
- A small amount
of Sulphur, S, is kindled on a deflagrating spoon, it burns with a
bright blue flame when introduced into a gas jar containing Oxygen,
O2. A gas, Sulphur Dioxide, SO2, is the main product of the
combustion. However, a little Sulphur Trioxide, SO3, is also formed,
which makes the gas slightly cloudy.
-
A dual absorption contact
process sulfuric acid plant that burns elemental sulfur. In the Frasch
process, elemental sulfur is melted, filtered to remove ash, and
sprayed under pressure into a combustion chamber. The sulfur is burned
in clean air that has been dried by scrubbing with 93 to 99 percent
sulfuric acid.
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The gases from the
combustion chamber cool by passing through a waste heat boiler and
then enter the catalyst (vanadium pentoxide) converter. Usually, 95 to
98 percent of the sulfur dioxide from the combustion chamber is
converted to sulfur trioxide, with an accompanying large evolution of
heat. After being cooled, again by generating steam, the converter
exit gas enters an absorption tower. The absorption tower is a packed
column where acid is sprayed in the top and where the sulfur trioxide
enters from the bottom.
Technology
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WSA technology for the
sulphuric acid plant and the design work started in November 2002 on
basis of a Letter of Intent. The contract for supply by Topsøe of
detailed engineering, all equipment and materials for the process
plant inside battery limits as well as first charge of catalyst .
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The Topsøe WSA process is
highly suited for treatment of sulphur containing gases with a wide
range of concentration of the sulphurous gas, ranging from a few
tenths of percent to strong gases. The process also accepts process
gas containing appreciable content of water that does not need to be
dried prior to processing. The process is extremely flexible and
adapts to large variations in feed gas flow and in concentration of
the sulphurous compounds.
Market
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Major sulphur producers
include the USA, Canada, Russia, Kazakhstan, China, Japan, Germany,
Saudi Arabia, which account for 65% of global volume. The global
sulfur industry remained divided into two sectors discretionary and
nondiscretionary. In the discretionary sector, the mining of sulfur or
pyrites is the sole objective; this voluntary production of native
sulfur or pyrites is based on the orderly mining of discrete deposits
with the objective of obtaining as near complete recovery of the
resource as economic conditions permit.
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In the nondiscretionary
sector, sulfur or sulfuric acid is recovered as an involuntary
byproduct; the quantity of output subject to demand for the primary
product irrespective of sulfur demand. Discretionary sources, once the
primary sources of sulfur in all forms, represented 10.5% of the
sulfur produced in all forms worldwide in 2005. Small quantities of
native sulfur were produced in Asia, Europe, and South America.
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The importance of
pyrites to the world sulfur supply has significantly decreased; China
and Finland were the only countries of the top producers whose primary
sulfur source was pyrites. About 80.0% of pyrite world production was
in China. Sulfur and sulfuric acid will continue to be important in
agricultural and industrial applications, although consumption will be
less than production. Because sulfuric acid consumption for phosphate
fertilizer production was expected to increase at a lower rate than
some other uses, phosphate may become less dominant in sulfur
consumption but remain the leading end use.
Entrepreneur who want the
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