Digging base Stone floor to prevent rising damp Harvesting termite clay Mixing clay Palm leaves for fiber Floor layer Furnace wall Internal diameter 25 cm Drying layer out Bridge over door way with sticks Clay over sticks I could do about 5 layers a day due to the slow drying of the clay It’s important not to rush building the furnace or it will slump Only add new clay when the last layer has stiffened Total height 175 cm, time taken 7 days. Making tuyere (air pipe) from clay. Inner diameter cm Blocking up doorway Positioning tuyere at 15 degree downward angle Tuyere nose sticks into furnace Bog ore formation about 1 km further down the creek Ore roasting Crushing ore to a powder Wood for the furnace (no charcoal was used in this experiment) Furnace stacked and lit from the top The tall furnace draws a strong natural draft. Adding wood and ore Fuel bed can be seen through the tuyere. Estimated at least 1200 c if not higher. After an hour and a half total, it was left to burn down.
The next day the tuyere was seen to have been covered with slag (no metallic iron though) Slag from the bottom of the furnace The slag was magnetic but had no metalic iron Natural draft furnace .