The cupola furnace was last used here as part of the carwheel foundry, where railroad carwheels were cast until the 1950's. The wall in front of you is the back wall of the building, and the arch behind you is the remains of the front wall of the original building. The foundry building was expanded considerably over time.
In the cupola furnace, iron was heated until it became molten, then poured into molds to produce various cast items. Furnaces at Tredegar once used pig iron from western Virginia, carried to this site by canal boats on the James River and Kanawha Canal, which forms the upper boundary of the Tredegar site. Electric furnaces replaced most cupola furnaces c. 1960-70 because they are easier to operate and more easily fulfill environmental regulations.
How cupola furnaces work
1. The furnace is charged with coke (a refined form of coal used as fuel) and iron is brought on small rail cars to a loading platform near the top of the stack.
2. The coke and iron are dumped into the brick-lined furnace in alternating layers.
3. As each layer of fuel falls into the melting zone, it melts iron above.
4. To make the fire hotter, air is blown into the wind belt through a pipe connected to a blower, and air is forced through openings or tuyeres in the inner part of the furnace.
5. When the iron has melted, the furnace is tapped, and hot metal flows into a ladle or crucible.
6. The ladle or crucible is taken to a mold and the hot metal is poured in.
7. Slag, composed of impurities created by the furnace, is taken off of the top of the melted iron and carried away.