Iron and Steel: A History

People have been producing iron and steel for thousands of years, heating up iron ores and limestone by burning charcoal, anthracite coal or coke (a fuel derived from coal) to create a sturdy metal. Iron-whether it is hammered ("wrought") into shape or cast into molds-tends to be either too brittle or soft. But, when treated by reducing the carbon content and adding various non-ferrous metals it is called steel.

In the 1850s, English inventory Henry Bessemer pioneered an efficient method for converting raw pig iron into steel. One of the earliest American companies to adopt this technology was right here in Bethlehem. The stone building and remains you see in the distance to the left are what's left of the double cruciform building. From 1873 to 1896, this structure housed Bethlehem Iron Company's Bessemer converters and rolling mills.

[Illustration key] , 1 Charging the Iron , The converter is pivoted down and molten pig iron is poured into the opening.

2 Making Steel , A blast of air is forced through the bottom of the converter. The oxygen in the air oxidizes (burns off) almost all of the carbon, leaving steel - a metal both strong and flexible.

3 Tapping the Furnace , Once this oxidation process is complete, the converter is tapped by pivoting the furnace and allowing the molten steel to pour out.