Pathways to African steel production: secondary steel production in miniature (vintengwe) furnaces in southwestern Tanzania, AD 1680–1950

Abstract

ABSTRACTThree distinct primary pathways to steel production have been identified, namely the Mediterranean, Chinese and African pathways. This paper focuses on African steel production, which has been argued to yield carbon-rich steel as a smelting product. Earlier work has, however, dealt with, and assumed the existence of, a single pathway to steel production in Africa, i.e. steel production as a smelting product whether in forced or natural draft furnaces. Because of this conviction the possibility of a secondary pathway to African steel production, with steel as a refining product, has been discounted. This paper presents ethnographic and archaeological evidence for a secondary (refining) pathway to steel production using miniature (vintengwe) refining furnaces in southwestern Tanzania. It also presents chemical and mineralogical data generated from refining slag materials in the vintengwe. The ethnoarchaeological and scientific data indicate that vintengwe refining furnaces were used to produce secondary carbon-rich steels through carburisation of a soft (low-carbon) iron product from smelting furnaces (malungu). These data constitute the first evidence for a secondary pathway to steel production in Africa as opposed to the well known primary pathway to steel through the use of ore smelting furnaces.