Valley Girl Views: Where The Iron Was Made

Tuesday, February 8, 2022

Where The Iron Was Made

How A Cold Blast Furnace Worked

"First the furnace was filled with charcoal and lit from the top. Over several days, the fire burned down to the openings, and the furnace was refilled with charcoal. Then the fire was allowed to burn back up to the top, and a blast of cold air from the bellows brought the temperature up to the ore-smelting temperature of 2300-2500.
As the charcoal settled, the furnace was continuously filled with layers of charcoal, ore, and limestone. As the iron or and limestone melted, the limestone served as a flux, cleaning impurities from the ore and forming slag, which floated to the surface of the molten.
During blast, the furnaces operated day and night in 12-hour shifts for three or four months, stopping only for maintenance and repairs. The iron and slag were usually tapped twice daily. The molten iron flowed into a casting bed made of sand A main trench (the sow) in the sand allowed the iron to flow into numerous smaller side trenches (the pigs), hence the name “pig iron.”

In one 24-hour period of operation, the Furnace could consume an average of 750 bushels of charcoal, 12 tons of iron ore, and many tons of limestone to produce five tons of iron. To produce the 750 bushels of charcoal needed for 24 hours of blast required 19 cords of wood, which means that about an acre of forest was cleared for each day of furnace operation. " (This was the best description I could find, and it came from a geocache listing!)
Once the iron was made into bars, it was shipped off to a foundry, where it was melted down and cast into various forms.
Iron Furnaces In The Central Susquehanna Valley(A Partial List)