iron

1. IRON
Iron is the chemical element with atomic number 26.
The word "iron" is used in common parlance to indicate low strength
"iron alloys" called mild steels. This element is always found linked
to others such as: carbon, silicon, manganese, chromium, nickel,
With carbon, iron forms its two best known alloys: steel and cast
iron. At an industrial level it is possible to obtain iron with a purity
that is close to 100%, this product is then used to be linked to other
chemical elements to obtain alloys with the most diverse
characteristics.
Iron (Fe), already known since ancient times, is one of the most
useful metals to man. Just think of the mechanical and automotive
industries, shipbuilding and construction, to understand the
importance that this metal has in modern life.
In nature, iron is almost never found in its pure state. The main
minerals from which iron is extracted are: magnetite, emanite and
limonite.
From geography we recall that the largest iron deposits are found in
the United States of America, Canada, Venenzuela, the Soviet Union,
Sweden and France.
In Italy there are large iron deposits in Cognein Val d'Aosta and on
the island of Elba.

2. Iron is extracted from ferrous minerals through a process called iron
and steel which is carried out in the blast furnace, a vat-shaped
construction, 20-30 meters high. The blast furnace is built with
refractory material, reinforced on the outside with iron sheets. The
charge is introduced from the upper part, ie a mixture of iron ore,
flux and coking coal.
The mineral is an iron oxide; flux is a material that must react with
the gangue and form slags which are then eliminated. The coke
serves as a fuel and at the same time removes oxygen from the
mineral.
At the bottom of the blast furnace, a strong current of air blown by
a machine enters through a nozzle. The air rises inside and activates
the combustion of the coal. Due to the high temperature reached in
the vat, the mineral is reduced to iron. This, going down into the
belly and into the dry, combines with a part of carbon. Finally, in the
crucible, the iron and carbon alloy, called cast iron, melts and
separates from the slag.
Cast iron is an alloy of iron and carbon that can contain 2 to 5%
carbon. From molten cast iron, by elimination of carbon, different
types of steel and soft iron are obtained.
Steel is tougher and more elastic than cast iron. Furthermore, steel
can acquire tempera, that is, it is capable of assuming a particular
hardness if, after being heated to a high temperature, it is suddenly
cooled in water or oil. When steels contain more or less high
percentages of other elements, they are called special steels and
have particular properties.

3. For three thousand years iron has accompanied and strongly
influenced the development of the most diverse civilizations. This
constant influence is due to the abundance of minerals that contain
iron and in particular to the extraordinary properties of this metal,
which is present everywhere, in homes as in cars, and also in our
blood.
HISTORY OF IRON
The first evidence of the use of iron comes from the Sumerians and
the Hittites, who already 4000 years before Christ used it for small
objects such as spear points and jewels made from iron recovered
from meteorites. Since meteorites fall from the sky, the ancient
Greeks called iron and what was related to it iron and steel Sider =
stars. However, it is difficult to understand the precise date of the
beginning of the use of iron because in some peoples it arrived earlier
in others later. The first peoples who used iron, however, are the
Assyrians, the Sumerians, the Hittites, the Babylonians and finally
the Persians
PROGRESS SYMBOL
In the spring of 1889 the citizens of Paris were able to follow, piece
by piece, the rapid completion of a new marvel of technology, built
by the French architect Gustave Eiffel with 15,000 beams of puddled

4. iron (steel) and over 300 m high: the immense Eiffel Tower, which
represented the symbol of the overwhelming force of progress.
On the other hand, two years earlier, the Statue of Liberty had been
inaugurated at the entrance to the port of New York, donated by the
French to the United States on the occasion of the first centenary of
the American Revolution. Almost 50 m high, it is supported by a
sturdy and complex steel scaffold, also designed by Eiffel.
From the historical point of view, the two great monuments, famous
all over the world, mark the highest point of an architectural style
which, starting from 1850, had begun to use iron as a privileged
material for load-bearing structures. The excellent physical
properties of this metal were exploited to construct buildings
characteristic of urban and industrial society, from railway stations
to covered markets, from department stores to the pavilions of the
many Universal Exhibitions of the time. The Iron Age celebrated its
triumph.
THE DAWN OF THE IRON AGE
Our distant, very distant ancestors prepared the first stone tools two
million years ago. Much later men learned to use metals, which are
harder and less brittle than stones. The first metal was copper,
followed by bronze, an alloy in which two different metals are
present: copper and tin. Bronze was much more sought after than

5. copper, because it was used to make weapons that then, 4,000 years
ago, were unrivaled.
The Bronze Age did not last long: after a thousand years, men
discovered that certain 'stones', red-hot until they became
incandescent, could be forged to make weapons for war and tools for
agriculture. We have thus arrived at the dawn of the Iron Age,
because the 'stones' used by our ancestors at the time were
fragments of meteorites, made up of more or less pure iron and
rained on the Earth from interplanetary spaces.
At different times and in different parts of the world, from China in
Asia to Angola in Africa, it was later discovered that with rather
complicated procedures and with temperatures much higher than
those necessary for copper, it was possible to obtain iron even from
outcropping minerals. on the surface of the ground, and present in
large quantities in the bowels of the earth. Wherever the production
of the new metal took hold, warriors armed with iron swords wiped
out enemies armed with bronze swords. In Italy, iron metallurgy
spread between ten and eight centuries before the birth of Christ,
that is, about three thousand years ago.
THE BIBLICAL IRON
From the beginning, iron has participated in the development of
civilizations with a double face: of progress in the production of
agricultural tools, and of barbarism in the creation of deadly

6. weapons. With this double role, iron has entered the culture of
peoples and has remained there to this day. In the religion of the
ancient Roman civilization from which we descend, iron was
associated with the force of Mars, the god of war. Instead, the red of
the rust that corrodes the iron was associated with the red of the
blood that stains the swords of the victors and gushes from the
wounds of the vanquished. Rome built its immense Empire with iron
swords, but precisely during the reign of the first emperor the poet
Ovid cast a horrified look at the endless series of wars waged by the
Romans. In the poem The Metamorphoses (early 1st century AD),
after dividing the history of humanity into different eras, Ovid wrote:
"The last was the ungrateful one of iron", and added "the harmful
iron was extracted and even more harmful / gold: and war appeared,
which is fought with both / and hurls crash weapons with bloody
hands ".
Iron is often mentioned in the Bible, and both aspects of its use are
presented. The spear of Goliath, the Philistine giant, had an iron tip,
but the tools of carpenters and agricultural tools were made from
iron. The Bible also mentions that the Philistines prevented the Jews
from practicing the blacksmith trade; only after David's victory over
Goliath the Jews were able to acquire the knowledge necessary to
melt and work iron.

7. A SYMBOL OF STRENGTH
In later times the techniques for dealing with substances took the
name of alchemy, a practice that associated laboratory procedures
with spiritual aspirations. The attempt to transmute base metals into
gold by means of the so-called philosopher's stone was often
described as a profound inner transformation. The philosopher's
stone was a powder or wax that could be reduced to a liquid state,
and so it was also called an elixir or tincture. The medieval mystic
and alchemist Jakob Böhme spoke of iron as follows: "a metal from
which dyeing, if you could extract it, you could get gold". In reality,
Böhme's phrase can be read in a mystical, spiritual sense: if the virile
strength of the body (the iron) could be transformed (the dye), a
higher knowledge (gold) would be obtained.
The positive symbolic function of iron can be found in many cultures.
In China, for example, iron was the symbol of strength and
righteousness, and in the same meaning it is also found in The
Periodic System of the great writer and chemist Primo Levi. In this
beautiful book of 1975 Levi entitled Ferro the chapter in which he
fondly remembers his friendship with Sandro Del Mastro, the janitor
of the Chemical Institute of Turin where Levi was studying: "Sandro
seemed to be made of iron, and was tied to iron by a ancient kinship:
the fathers of his fathers, he told me, had been boilermakers -
magnin - and blacksmiths - fré - from the Canavese valleys ".

8. But we can all make a collection of the idioms that are still used today
about iron: from the expression of a strong sense of security ("I'm
in an iron barrel") to the superstitious invitation that appeals to
beneficial properties of metal ("touch iron").
THE PROPERTIES OF IRON
Physical properties. We have certainly seen the pans with holes in
which roast chestnuts are prepared. Like all iron objects, the pans
have a very dark color; we are therefore surprised that iron in its
natural state, but not in contact with the air, appears as a silvery
white metal, as bright as platinum.
Iron obviously shares a number of important properties with other
metals: it conducts electricity and heat well; it can be deformed with
some ease (it is malleable) and it can be pulled into threads (it is
ductile). It is precisely in the evaluation of the mechanical properties
of iron wires that we discover why this metal was
reserved a place of honor in the construction of buildings and in
major architectural works such as the Eiffel Tower. An iron wire with
a cross section of 1 mm2 can lift a weight of up to 40 kg without
breaking. This is a very high tensile strength, but in a workmanlike
construction a safety tensile strength is used which is four times
smaller, as if our line could only hold 10 kg. Despite this very strong

9. limitation, it is calculated that an iron rod with a diameter of 16 mm
can withstand the traction of a weight of 2 t. This explains the
remarkable fact that the 312 m high Eiffel Tower weighs less than
7,200 t (as much as 200 trucks can carry).
Chemical properties. The chemical symbol for iron is Fe. It is a very
abundant chemical element in the earth's crust, of which it
constitutes almost 5% by weight. Going deeper, towards the center
of the Earth, it becomes the dominant element because it constitutes
90% of the core of the Earth. The minerals that contain iron are many
and widespread everywhere, but here we mention only two. Pyrite
(formula FeS2) contains iron and sulfur and often presents itself with
beautiful cubic crystals of a golden yellow color. Completely different
in appearance, of a shiny black, is the magnetite, a combination of
iron and oxygen (formula Fe3O4). The name magnetite derives from
the Greek name of certain mysterious stones coming from the city of
Magnesia, a locality of present-day Turkey, which had the ability to
attract iron: the name of the magnetite derives from the set of
phenomena we call magnetism.
The chemical properties of iron also make this element very
interesting. In fact, its ability to react is intermediate between that
of highly reactive metals, such as sodium, and that of noble metals
such as platinum. A small piece of sodium thrown into water
decomposes it immediately, and develops so much heat that it
ignites the hydrogen that is formed. The iron must instead be
brought to a high temperature to be able to decompose the water.
This reaction was discovered by the French chemist Antoine-Laurent

10. Lavoisier, who in the second half of the 18th century used it to obtain
hydrogen in large quantities to inflate balloons.
Among the many compounds of iron, ferrous sulphate (FeSO4) must
be remembered, which finds numerous applications in preparing
fabrics for dyeing, in the production of inks, or as a wood protector.
RUST
In the absence of humidity, the iron is not deeply affected by oxygen
from the atmosphere. It gets covered with a sticky layer of oxide,
and it all ends there. But when an iron object is in contact with water
(the humidity of the atmosphere is enough), the joint action of water
and carbon dioxide present in the air causes corrosion of the metal:
on the surface of the iron they form like tiny piles which, through
their electrical activity, give as a final product a particular iron oxide,
rust, which is no longer able to adhere to the metal. Rust, the terrible
enemy of iron, easily detaches from the surface, and water, oxygen
and carbon dioxide continue their work inexorably until the complete
destruction of the iron object. For this reason, the iron objects
exposed to the elements are protected with anti-rust paints.

11. A MISTERY
One of the best uses for the ownership of a mysterious iron rift
through the many centuries. Mutual Attraction of Iron and Magnetite
was known as Middle Eastern civilization and in Greek; but that a
magnetized object tends to orient itself in the north-south direction
was discovered by the Chinese in the 4th century BC. The Chinese
obtained the first compasses by placing a spoon made from
magnetite on a smooth bronze plate; left to itself, the spoon always
turned in the same direction. Many centuries later, between the 7th
and 8th centuries, Chinese studios resorted to magnetizing iron
needles by rubbing them on magnetite. At the same time, the
compass began to spread across Europe, facilitating a journey into
the depths of the sea.
The physical phenomenon underlying the functioning of the compass
had rather fantastic instructions until the nineteenth century. Now I
know that the magnetism of materials is due to the particular
orientation properties of certain atoms, including those of iron.
Normally the atoms are a steel tone one-fa oriented in all directories,
and the needle is not present in a magnetized Romanian magnetic
field.

12. The property is magnetic and made of steel, indispensable through
the electrical industry and the manufacture of scientific and healthy
instruments.
Iron in living things
Iron and blood are inseparably linked by the insane use of weapons,
but biochemistry has discovered a very different, and truly vital,
relationship between the iron element and life. In complex living
beings, made up of billions of cells, the oxygen necessary for life
processes must be transported from the outside of the organism to
the cells. The transport of oxygen is performed by particular
molecules, called respiratory pigments. These molecules contain iron
atoms that are able to bind the oxygen of the atmosphere and
release it where the cells need it to perform all the physiological tasks
to which they are assigned, accepting in exchange carbon dioxide, a
waste product of the cells. . In Vertebrates (and therefore also in
humans) oxygen is transported by hemoglobin, a molecule present
in red blood cells, which has four iron atoms in its structure. In the
lungs, the four iron atoms of hemoglobin release the waste carbon
dioxide molecules and bind one molecule of oxygen each to transport
it to cells throughout the body.
Our blood is colored red because hemoglobin can be considered a
real red dye or pigment. Hemoglobin, dark red or bright red
depending on the oxygen content, is present in almost all animals,
from fish to mammals. In some molluscs and crustaceans, oxygen

13. transport is carried out by molecules of hemocyanin, a colorless or
blue substance, which contains copper instead of iron.
THE IRON AGE CONTINUES
Iron changes its mechanical characteristics according to the
processes to which it is subjected, but the modifications become
radical when the iron is alloyed with carbon. If the percentage of
carbon is between 2 and 5.5% we have cast irons, if it falls below
1.8% we have steels. There are many special types of cast iron and
steel, for an infinite number of different uses. It is therefore easy to
understand how iron continues to dominate the world metal market,
with a percentage that exceeds 90% of all metals produced. In 2004,
the annual world production of iron exceeded one thousand million
tons!
Such a massive production poses major problems, both from the
environmental point of view and from that of an intelligent use of
natural resources. Throughout Europe and North America the steel
industry is significantly reducing environmental damage, and on the
other hand the two points of view, the environment and the
economy, converge in the search for a solution acceptable to all: the
recycling of ferrous materials. The United States is particularly
advanced in this direction: in 2003 ferrous materials were recycled
for 69 million tons, equal to 70% of the total steel production. The

14. magnetic properties of iron and steel make these materials easily
recoverable, even when they are reduced to small fragments. Let's
take the case of the cans used to preserve food. When we put the
cans to be recycled into the waste containers we do not know if they
are made of aluminum or ferrous materials (steel or iron tinplate),
but when the cans arrive at the recycling plant a simple passage
through a magnetic machine holds the cans of iron and let the
aluminum ones pass.