Colonial-era industrial espionage
The Royal Iron Foundry of São João de Ipanema was established by a royal charter on December 4, 1810. Its primary purpose was to give the Portuguese Crown, then based in Rio de Janeiro, a domestic source of iron for military hardware, breaking its dependence on English imports. The site, near modern-day Iperó, was chosen for its proximity to magnetic iron ore at Araçoiaba Hill and the availability of forests for charcoal and rivers for power.
To acquire the necessary technology, the Crown hired a team of Swedish technicians led by metallurgist Carl Gustav Hedberg in 1809. Sweden, a leader in iron production, was reluctant to share its advanced blast furnace techniques. The contract stipulated that Hedberg's team would build the foundry and teach the "art of metallurgy" to Luso-Brazilians. However, the project started with a multi-year fiasco. Instead of the expected large-scale blast furnaces, Hedberg constructed four small, inefficient furnaces based on a direct-reduction method, producing only three tons of very poor quality iron in four years. Historians debate whether this was intentional industrial sabotage or a result of mismanagement and a failure to adapt to local conditions. After Hedberg was dismissed in 1814, German military engineer Friedrich Ludwig von Varnhagen took over, finally constructing the first true blast furnaces in 1815.
Furnaces, iron, and forced labor
The Ipanema foundry's twin blast furnaces, whose ruins are still visible, began heavy industry in Brazil. They were fueled by charcoal produced from the surrounding Atlantic Forest and smelted magnetite ore from the nearby hills. The first successful production of pig iron in these blast furnaces occurred on November 1, 1818. At its peak under later management, the foundry was connected to the mine by a 4-kilometer railroad.
The difficult and dangerous work of operating the foundry was performed by enslaved Africans. They were involved in all stages of production, from extracting ore and cutting timber for charcoal to the grueling tasks of tending the furnaces. While the foundry also employed skilled European workers—Germans, Swedes, and later Austrians brought new refining techniques—the operation depended on the forced labor of the enslaved. The complex produced military items like cannons and ammunition, and supplied the civilian economy. It manufactured about 200 iron mills for the sugar industry, which were more efficient than the existing wooden ones, along with household goods like pans and tools.