The objectives in Blast Furnace operation are two-fold. The
first objective is to reduce the iron ore to liquid metallic iron.
The second is to control as far as possible the quantities of impurities
which find their way into the iron either wholly or in part.
The first intentional attempt to extract iron from iron ore in
a furnace-type of container was in Catalonia, Spain (circa.1300
A.D.) where a 'Catalan' forge (basically,a scaled-up blacksmith's
forge) was used to produce iron. The Catalan forge was anywhere
from 20 inches square and 16 inches deep to around 30 inches by
40 inches square and something over 2 feet deep. The nozzle (or
tuyere), through which the blast was blown into the furnace, was
placed about 9 inches from the bottom in the smaller hearths and
about 15 inches from the bottom in the larger hearths.
The hearth was filled to the level of the tuyere with charcoal,
on which was piled lumps of iron ore mixed with charcoal. These
materials were placed so as to form two separate columns, the charcoal
against the tuyere side of the hearth, and the ore against the other
side. A gentle blast of air was applied at first and the carbon
monoxide, formed by combustion of the charcoal, passed through the
open pile of iron ore. The ore was reduced to metallic iron when
the oxygen in the iron oxide of the ore combined with the carbon
monoxide to form carbon dioxide.
The waste gases escaped at the top of the charge. The metallic
iron resulting from the reduction of the ore became pasty enough
to form a coherent 'bloom'. After as much as possible of the ore
had been reduced, the bloom was pried out of the hearth and hammered
into bar form. Thus began the series of developments from the small
stone-built structure capable of producing 50 tons of pig iron a
year to the modern 100-foot tower with a capacity of more than 2,000
tons a day.
Les Forges Saint-Maurice in Quebec was Canada's historic first
ironworks, producing castings and wrought iron bars from a charcoal-fired
blast furnace in 1738. Care must be taken to distinguish between
the French term 'Les Forges' and the English word 'Forge' (blacksmithing).
In French historical writings, 'Les Forges' has a very broad meaning.
It signifies a complete ironworks establishment. This included the
blast furnace as well as the foundry, pattern shop and all the facilities
for re-heating pig iron and hammering out wrought iron bars.
Usually the term also included the associated ore collection, charcoal
burning, storehouses, workmen's quarters, etc., i.e. the whole pioneer
industrial community. All the necessary raw materials for the manufacture
of iron were found in abundance within a few miles of the blast
furnace at Saint-Maurice. The blast furnace at Les Forge Saint-Maurice
is known to have been thirty feet in height. It can be described
briefly as a cold blast, charcoal-fired furnace employing water
power for the air blast and the associated forge hammer, for making
wrought iron bars. The blast furnace was eventually abandoned in