抄録
Archaeologists have classified the ancient and medieval shaft furnace into three types; "rectangular box", "self-standing" and "partly-undergrounded". Although the shaft wall lost its original shape, they have tried to pick up the brick pieces and reconstruct the wall. The heights of the restored shaft are reported to be ranging from about 50 to 70 cm. The author supposes that such a low shaft furnace could not have been able to smelt iron sand in liquid state.
Under the optical microscope, graphite carbon, ledeburite and primary-crystallized cementite were observed in the inner part of metal-rich relics and identified to be the remaining structure of pig iron before decarbonization. Fair amounts of Cu, P, Ni and/or Co were contained in the excavated pig iron sample. These elements are estimated to originate in the raw magnetite ore. Analytical results of the samples taken from the three types furnace ruins have not shown any distinguishable relationship among the main slag components.
It was considered that most of the ancient and medieval furnaces were operated for steelmaking of pig iron.
