Artisanal mining in the Dem region, Burkina Faso: the mining processing and production of iron ore
Funyufunyu, Tondani Advice
Artisanal and small-scale mining (ASM) has been a crucial industry in Africa for centuries. In Burkina Faso approximately 95 kms northeast of the capital city Ouagadougou near the village of Dem and on a ferricrete capped ridge to the west of the village, it is possible to find a number of opencast workings and underground mines that show evidence of extensive artisanal mining for iron. Iron mining worked quartz-vein hosted and lateritic ore. Nearby, waste piles, processing sites and at least eleven (11) Bloomery furnaces are exposed on the alluvial plain. Petrographically the ore bearing rocks consist of goethite-hematite as the dominant oxides with silica. Geological and ethnographic studies conducted in 2011 focussed on detailing and mapping the mine site and host rocks (including ore rocks), and establishing the age of mining, processing and forging of ore. Selected charcoal samples were collected from furnaces sites. Limited AMS radiocarbon dating of six (6) samples was performed at Beta Analytic laboratory in Miami, Florida, USA and suggested that iron forging may have begun in the 15th century, which could also be the age of mining and processing of ore. The site has characteristics such as impure slag, eleven (11) large furnaces, hundreds of tuyeres, and crucibles, and clay fragments. Remnant slag samples were collected for petrographic and mineralogical study to deduce the mineral composition of the slag. The slag samples contained high concentration of fayalite, quartz, magnetite and hematite and low concentration of iron metal and ulvospinel suggesting an iron silicate slag of low melt temperature was formed in the furnaces.
A dissertation submitted to the Faculty of Science, University of the Witwatersrand Johannesburg in partial fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2013.