Ask A Scientist Chemistry Archive

   
status student 
age 18 

Question - Why pig iron is called pig iron? 
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As you may or may not know, PIG IRON is raw iron in an ingot form.  It is the 
immediate product of smelting iron ore with coke and limestone in a blast furnace.  
It is a hard but brittle mix of iron (90% or more) and carbon (typically 4-5%), 
manganese, sulfur, phosphorus, and silicon (roughly 3% in total).  It requires 
further treatment in a bessemer converter or basic oxygen furnace to produce steel 
or wrought iron.  

The name is derived from the time when the iron ran into molds in sand beds fed from a 
common runner.  The row of molds was said to resemble a litter of suckling pigs, hence 
the individual ingots were referred to as pigs and the runner was called the sow.  I 
hope that this aswers your inquiry.

The above information was exerpted from Wikipedia.org.

Sincerely,

Bob Trach 
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The term "pig" has its origins in the word "furrow" or trench-like shapes (in
Old English, the naming of an animal sometimes comes from its attributes, 
so I
guess the animal was named for the furrows that it makes with its snout).
So "pig" in this case really means the oblong-shaped mold into which molten
metal is run.

-Greg
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Pig Iron

Because blast furnaces produced increased quantities of iron from the ore,
the molten iron was cast into bars, called pig iron, for later
remanufacturing.

The furnaces were built and operated for the purpose of extracting iron from
the native iron ores. The objective was to form bars of cold cast iron for
transfer to a foundry for later remanufacture. These were made in molds
pressed in the very dry sandy floor. A main trench directed the molten iron
to a distribution trench from which many side branches were formed. The
molten iron was cast into bars called "pigs"; hence, the common name of "pig
iron."

The name pig iron is meaningless to non-farm people, as it is a figment of
the imagination of the blast furnace workers--all of whom were very familiar
with the keeping of pigs. Workers before World War I were, in almost all
cases, required to have a kitchen garden, and keep cows, chickens and pigs.
This was a matter of survival and considered part of the compensation in a
company town or village. The workers were very familiar with the appearance
of a mother pig, called a sow, and her dozen or more nursing piglets. As
they looked at the molten iron flowing from the hearth in the base of the
furnace stack, the trench of red iron with the many short side branches made
them think of a sow (the large feeder trench) and pigs (the end result).

As Robert Frost would say, "One has to be schooled in country things."

The site where I found the above material is
http://www.oldeforester.com/ironintr.htm.

Regards,


Todd Clark, Office of Science
U.S. Department of Energy
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Just guessing:

A certain old way of smelting iron makes a big, irregular, crusty chunk of 
dirty iron.  Heavy, too.
Perhaps blacksmiths, making this chunk over and over for a living, wanted 
a one-word name for it, and it vaguely reminded them of a pig.

If we can have coveys of quail and pods of whale, why not pigs of iron?

Verbal inertia being what it is, today "pig iron" refers to a crude grade 
of iron, similar in properties or preparation chemistry to that old method.

Jim Swenson
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