A Blast furnace is a buildable structure in Valheim.
It is an upgraded version of the Smelter, although it can't smelt the ores that the Smelter can.
It can hold a total of 20 coal and 10 ores.
Blast furnaces can be placed directly onto terrain and stone structures. Currently, they cannot be placed on wood structures but it is possible to bypass this to a extent by terraforming terrain with a Hoe to be in line with wooden floors.
Unlike the Smelter, Blast furnaces have both of their refueling ports to the LEFT of the bar chute.