Creative Chemistry: Descriptive of Recent Achievements in the Chemical IndustriesSlosson, Edwin E. (Edwin Emery)
Science
Creative Chemistry: Descriptive of Recent Achievements in the Chemical Industries
Slosson, Edwin E. (Edwin Emery)
Chemistry, Technical
The Haber process for the making of ammonia by direct synthesis from its
constituent elements and the supplemental Ostwald process for the
conversion of the ammonia into nitric acid were the salvation of
Germany. As soon as the Germans saw that their dash toward Paris had
been stopped at the Marne they knew that they were in for a long war and
at once made plans for a supply of fixed nitrogen. The chief German dye
factories, the Badische Anilin and Soda-Fabrik, promptly put
$100,000,000 into enlarging its plant and raised its production of
ammonium sulfate from 30,000 to 300,000 tons. One German electrical firm
with aid from the city of Berlin contracted to provide 66,000,000 pounds
of fixed nitrogen a year at a cost of three cents a pound for the next
twenty-five years. The 750,000 tons of Chilean nitrate imported annually
by Germany contained about 116,000 tons of the essential element
nitrogen. The fourteen large plants erected during the war can fix in
the form of nitrates 500,000 tons of nitrogen a year, which is more than
twice the amount needed for internal consumption. So Germany is now not
only independent of the outside world but will have a surplus of
nitrogen products which could be sold even in America at about half what
the farmer has been paying for South American saltpeter.
Besides the Haber or direct process there are other methods of making
ammonia which are, at least outside of Germany, of more importance. Most
prominent of these is the cyanamid process. This requires electrical
power since it starts with a product of the electrical furnace, calcium
carbide, familiar to us all as a source of acetylene gas.
If a stream of nitrogen is passed over hot calcium carbide it is taken
up by the carbide according to the following equation:
CaC_{2} + N_{2} --> CaCN_{2} + C
calcium carbide nitrogen calcium cyanamid carbon
Calcium cyanamid was discovered in 1895 by Caro and Franke when they
were trying to work out a new process for making cyanide to use in
extracting gold. It looks like stone and, under the name of
lime-nitrogen, or Kalkstickstoff, or nitrolim, is sold as a fertilizer.
If it is desired to get ammonia, it is treated with superheated steam.
The reaction produces heat and pressure, so it is necessary to carry it
on in stout autoclaves or enclosed kettles. The cyanamid is completely
and quickly converted into pure ammonia and calcium carbonate, which is
the same as the limestone from which carbide was made. The reaction is:
CaCN_{2} + 3H_{2}O --> CaCO_{3} + 2NH_{3}
calcium cyanamid water calcium carbonate ammonia
Another electrical furnace method, the Serpek process, uses aluminum
instead of calcium for the fixation of nitrogen. Bauxite, or impure
aluminum oxide, the ordinary mineral used in the manufacture of metallic
aluminum, is mixed with coal and heated in a revolving electrical
furnace through which nitrogen is passing. The equation is:
Public-domain text, read in full here on John Shaqi.
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