The Ancient Steelmakers of Tanzania

Around 2000 years ago, the Haya people of northwestern Tanzania invented an advanced iron smelting technology to produce high-grade steel at 1800 degrees Celsius. (Europe’s furnaces only reached this temperature and produced this kind of steel in the 19th century.)

In the 1970s, anthropologists in Tanzania were studying the history of the Hayas, when they learned about an ancient blast furnace used to produce steel. The researchers wanted to see a working furnace, but the Hayas had stopped making steel early in the 20th century after cheap steel imports had put them out of business.

At the request of the researchers and working from memory, a few 80 to 90 year old Haya elders attempted to recreate the blast furnace of their childhood and ancestors. The result was 1.5 metres high, cone-shaped, made of clay, and built over a pit. The elders filled the bed of the furnace with partially burned swamp reeds (which provided the carbon that combined with molten iron to produce steel), and placed the charcoal and iron ore above that. Air was pumped in using eight sets of bellows on the outside of base of the furnace. The air flowed through clay pipes that extended into the furnace chamber, and this pre-heated air then blasted into the charcoal fire itself. The result was temperatures higher than 1800 degrees Celsius along with fine, tough steel.

Further excavations discovered 13 other furnaces nearly identical in design to the one built by the Haya elders, and carbon-dating found that some of the furnaces were 2000 years old. This indicates that steelmaking—one of the greatest scientific breakthroughs of all time—emerged independently among the Haya, and served its people for 2000 years, before it was almost forgotten.

By Rahim Mawji

(Image: Schmidt and Avery)

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