(during 1913), it was equivalent to only about 3% of the Chilean fixed
nitrogen exports and less than 5% of what was available by other means. Low
yields coupled with an energy input of around 180–270GJt
−1 of fixed
nitrogen made this method unsustainable in the long term
5
—especially for
Germany.
Other commercial processes that returned ‘fixed’ nitrogen were based on
ammonia by-product recovery obtained from coking plants, and the ‘cyanamide’ process. ‘Coke’ (impure carbon) was needed for ‘pig-iron’ smelting and
for the generation of ‘coal gas’ used in gas lighting. Coke in turn was produced from coal by heating it in the absence of air. Now, coal contains
around 1–1.5% nitrogen, arising from the decomposition of proteins present
in the original biomass. When the coal is heated in the absence of air some of
the nitrogen is released as ammonia. For decades the ammonia was an
unwanted by-product and released to the atmosphere. With a growing
understanding of the importance of ammonia, coking ovens were modified to
achieve by-product recovery, which for ammonia commonly meant its conversion into ammonium sulphate (NH 4 ) 2 SO 4 . Coke by-product recovery was
largely confined to Western Europe and the United States and by 1900 the
total annual global output was around 0.5 Mt ammonium sulphate. By
1913,
12 German by-product recovery output alone accounted for almost two
thirds of the global output of fixed nitrogen by this means, but Chilean
saltpetre exports were still larger accounting for almost twice that amount. By
1910, the German output of ammonium sulphate had exceeded the British
total but this was still only about half of what she needed. During the first
world war the demand rose sharply. The extract below taken from the
Manuals of Chemical Technology—III,
12 (p. 45), describes an advanced
by-product recovery process in operation widely in Germany by 1915 and
illustrates the investment made here (Fig. 3.1).
An earlier means of fixing atmospheric nitrogen was discovered in 1860.
The original process employed barium carbonate at 1200 °C according to;
BaCO 3 þ N 2 þ 4C ¼ BaðCNÞ 2 þ 3CO
the cyanide subsequently being converted to ammonia and barium hydroxide
in the presence of water vapour. Later versions used much cheaper calcium
carbide which produced ’cyanamide’ rather than the cyanide. The carbide was
produced by the fusion of lime and carbon (‘coke’) in an electric furnace;
3 Germany and ‘Fixation’
85
nitrogen exports and less than 5% of what was available by other means. Low
yields coupled with an energy input of around 180–270GJt
−1 of fixed
nitrogen made this method unsustainable in the long term
5
—especially for
Germany.
Other commercial processes that returned ‘fixed’ nitrogen were based on
ammonia by-product recovery obtained from coking plants, and the ‘cyanamide’ process. ‘Coke’ (impure carbon) was needed for ‘pig-iron’ smelting and
for the generation of ‘coal gas’ used in gas lighting. Coke in turn was produced from coal by heating it in the absence of air. Now, coal contains
around 1–1.5% nitrogen, arising from the decomposition of proteins present
in the original biomass. When the coal is heated in the absence of air some of
the nitrogen is released as ammonia. For decades the ammonia was an
unwanted by-product and released to the atmosphere. With a growing
understanding of the importance of ammonia, coking ovens were modified to
achieve by-product recovery, which for ammonia commonly meant its conversion into ammonium sulphate (NH 4 ) 2 SO 4 . Coke by-product recovery was
largely confined to Western Europe and the United States and by 1900 the
total annual global output was around 0.5 Mt ammonium sulphate. By
1913,
12 German by-product recovery output alone accounted for almost two
thirds of the global output of fixed nitrogen by this means, but Chilean
saltpetre exports were still larger accounting for almost twice that amount. By
1910, the German output of ammonium sulphate had exceeded the British
total but this was still only about half of what she needed. During the first
world war the demand rose sharply. The extract below taken from the
Manuals of Chemical Technology—III,
12 (p. 45), describes an advanced
by-product recovery process in operation widely in Germany by 1915 and
illustrates the investment made here (Fig. 3.1).
An earlier means of fixing atmospheric nitrogen was discovered in 1860.
The original process employed barium carbonate at 1200 °C according to;
BaCO 3 þ N 2 þ 4C ¼ BaðCNÞ 2 þ 3CO
the cyanide subsequently being converted to ammonia and barium hydroxide
in the presence of water vapour. Later versions used much cheaper calcium
carbide which produced ’cyanamide’ rather than the cyanide. The carbide was
produced by the fusion of lime and carbon (‘coke’) in an electric furnace;
3 Germany and ‘Fixation’
85