Twentieth-century Bena iron production in the Njombe district of Tanzania

Abstract

ABSTRACT This paper focuses on Bena iron production in southern Tanzania to determine the geochemistry of smelted iron ore, verify liquid slag tapping mechanisms, explore the efficiency of iron production and identify the nature of final smelting products. To this end, chemical and mineralogical analytical techniques were used. Analytical results indicate that the Bena smelted titanium-rich iron ores to produce iron. It appears that liquid smelting slag was tapped out of the furnace through mlepulo, a local name for a channel or tunnel dug a few centimetres below the tuyères at a horizontal level. The slag microstructures strongly indicate that smelting tap slag cooled rapidly. This study also shows that the reduction process of Bena iron production was efficient in many respects due to the absence of high iron oxides in the slag microstructures. Based on the smelting slags’ chemistry and mineralogy, this paper argues that the Bena produced iron instead of carbon-rich steel.