Inorganic Chemicals - Fundamentals of Industrial Chemistry: Pharmaceuticals, Polymers, and Business - page 6

water and oxygen, pyrite can be converted to sulfuric acid. China is a leading
miner of pyrite and extraction of sulfuric acid from pyrite is an important
process in China. The pyrite is roasted to form sulfur dioxide which is then
purified and converted to sulfuric acid [5].
A major source of sulfur is refinery and natural gas streams. This is done
by the Claus process which was discovered more than 100 years ago and
has been used by the natural gas and refinery industries for 50 years. In
the Claus process, hydrogen sulfide from the gas stream is converted to
elemental sulfur. Air is introduced into a furnace to oxidize about one-third
of the hydrogen sulfide to sulfur dioxide. In the next stage, the reaction
furnace, unconverted hydrogen sulfide reacts with the sulfur dioxide to form
elemental sulfur. The Claus process generally produces an overall recovery
of sulfur of 95 - 97%, but several modifications have been invented and sulfur
recoveries of 99.9% are now achievable [6]. The chemistry is represented by
the following reactions; the equilibrium to form elemental sulfur is favored
at lower temperatures.

2 H 2 S + 3 O 2 2 SO 2 + 2 H 2 O

2 H 2 S + SO 2 3 S + 2 H 2 O

The leading U.S. producers are the refining companies such as Valero
Energy Corp., Exxon Mobil Corp., Conoco Phillips Co., Chevron Oil Co.,
and Shell Oil Co. In 2011, elemental sulfur and byproduct sulfuric acid were
produced in the United States at 109 operations in 29 states and St. Croix with
total shipments being valued at $1.6 billion [7]. The production took place
at petroleum refineries, natural-gas processing plants, and coking plants.
About 90% of consumed sulfur is in the form of sulfuric acid. Production of
fertilizers is the major use of sulfuric acid, followed by petroleum refining
and metal mining. U.S. production data for 2009 is estimated at 9.8 million
metric tons of sulfur. If this number is converted to a sulfuric acid basis, it
becomes 30 million metric tons.

98 formula weight
sulfuric acid
32 formula weight sulfur =

9 . 8 million metric tons × 30 million metric tons

The population of the U.S. is around 300 million people, so this is equiv-
alent to each and every person in the United States making 0.1 metric tons
each year. A metric ton is 1,000 kg or 2,240 pounds (not to be confused with
a U.S. ton which is 2,000 pounds) so this is equivalent to each person making