Science: Allaire Village (HTHS Geology Project)

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Operation of a Blast Furnace

Charge of coke from coal or iron (C), iron ore (Fe₂O₃), and limestone (CaCO₃) added
Air (O₂ needed for combustion) enters furnace
Reducing Zone
1. C + O₂ CO
2. Fe₂O₃ + CO CO
Slag Production & Draining
1. Impurities in ore separate and react with limestone to produce slag (waste)
  CaCO₃ + SiO₂ CaSiO₃ + CO₂
2. Less dense slag (CaSiO₃) floats above iron ore and is drained off
Molten Iron (Fe) is drained out to be formed into pig iron

To produce one ton of pig iron...

265 bushels of charcoal- Colliers made the charcoal in smoky mounds of sand and turf using large amounts of the native pine from vast Pinelands forests. Charcoal burned slowly with just the right intensity.
2 tons bog iron- See the Bog Iron Page
Seashell Lime (Flux)- The seashell lime used as flux to carry off impurities during the smelting process was available locally and was even conveniently gathered together in heaps. Archaeologists speculate that some of the great shell piles left behind by the native Lenape Indians were carried off to serve the furnaces.
Repeat for each charge (layer)

Why "pig iron?"

The iron cast directly from the furnace is called "pig iron" because of the shape of the molds, which is said to resemble suckling pigs at their mother.

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