Traditional Steelmaking in Southwestern Ethiopia: A Metallurgical Analysis

抄録

We documented the reconstruction by local blacksmiths of obsolete traditional steelmaking methods in Dime, southwestern Ethiopia, and metallurgically analyzed the materials and products associated with this technology. The steelmaking operation was successfully recreated in 2004, including mining, furnace construction, and charcoal production. The produced sponge iron had a yield ratio of about 40%, contained 0.31~0.48 mass percent carbon, and lacked impurities. The collected slag contained typical components (iron, silicon, aluminum, potassium, phosphorous, titanium, manganese). The blacksmiths used three kinds of iron ore (balt, bullo, gachi) that consisted primarily of goethite [α-FeO(OH)] and kaolinite (Al₂O₃ · 2SiO₂ · 2H₂O); white inclusions in gachi contained calcium phosphate hydrate [Ca₃(PO₄)₂ · xH₂O]. The local blacksmiths specifically preferred gachi for steelmaking; the reasons for this selection were discussed from the viewpoint of slag-forming ability. Comparison of Dime steelmaking with other traditional steelmaking methods confirmed the independent development of geographically specialized knowledge and steelmaking techniques in Dime, as in Europe and Japan.