Steelmaking in a bloomery furnace: behaviour of manganese.
A research on the Ferrum Noricum process
After the discovery in 1774, of the manganese metallic nature by Swedish chemists, the understanding by the metallurgists of its role as a chemical agent in the steelmaking processes required several decades, until the Bessemer-Mushet’s invention which proved to be indispensable as a deoxidizing and desulphurizing agent.
After 1875, the achievement of the production in blast furnaces of the commercial ferromanganese, a very competitive alloy, the specialized enterprises jealously kept their secrets of manufacture until the decline of the process a hundred years later. The data about the manganese extractive metallurgy remained therefore, rare, fragmentary, and hardly accessible.
However, from the results of archeological excavations and experimental works, from historic sources on the metallurgy of iron in the catalan furnace and in the blast furnaces at the beginning of the 19th century, and from modern technical and professional publications, it is now possible to understand the reasons why, since the Early Iron Age, manganese, present but unsuspected in some iron ores (manganiferrous siderite and bog ores), played an important role in the steelmaking bloomery.
A better knowledge of its behaviour permits to propose a hypothesis on the process of steelmaking bloomery by formation and selective reoxidation of a manganese-rich cast iron.
Keywords: manganese, steel, bloomery, cast iron, re-oxidation
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