"J. H. Brothers" wrote:
I'm not going to claim to be an expert on European cast iron, but I think there
is now fairly compelling evidence that "blast furnaces" date from at least
around 1200. There are some pretty early ones, 100-1200, showing up in
Scandinavia, Germany, and Austria. Unfortunately, most of the literature I have
seen is not available in English. ....
I am not an expert on European cast iron as well. But ...
We have some strong evidence that pig iron (carbon rich iron in the molten state,
Flusseisen, white and gray raw iron) has been producedas early as in the 13th.
century in the Sauerland preindustrial region (South to the later Ruhrgebiet
industrial complex). The aim was very probably not to invent another metallurgical
technology but to produce iron with some more efficiency and using less iron rich
ores - in maintaining comparable energy consumption, i.e. at comparable
temperatures. This was achieved by a process resulting in slags considerably
enriched in SiO2 AND K2O, relatively to the old "Rennfeuer"-process, and high
carbon iron,
see
http://www.uni-muenster.de/GeschichtePhilosophie/UrFruehGeschichte/kier2.htm
http://www.uni-mainz.de/FB/Geo/Geologie/archaeo/KERSPE/KerspeRes.html
We have no evidence so far that the "new" product immediately has been used as cast
iron, i.e. to produce iron objects in moulds. Instead the old methods of forging
carbon poor iron have been maintained too. The
transformation of "Flusseisen" to malleable qualities was achieved through
remelting the carbon-rich primary
product within a fayalitic slag, resulting in the so called "Osemund-Luppe". The
now obtained iron quality seems to have been rather inhomogeneous and rich in slag
inclusions. Homogeneization and at the same time strengthening with the aid of the
slag inclusions (!) has been achieved by damaszening, a process widely used during
various historical periods (or continuously applied ?) to obtain good quality iron
objects. One of the next steps was to combine layers with different carbon contents
in this manner that the fabric of a simple chain-link became directly comparably
with that of a (younger) Edom-time Japanaese sword. Pictures will soon bee
available in the web - with explications in German (see the recent remark of James
Fussel in the mining history news group).
Ingo Keesmann
__________________________________________________________
Arbeitsgruppe Archaeometallurgie
Institut fuer Geowissenschaften
Johannes Gutenberg-Universitaet Mainz
D-55099 Mainz (Germany)
Telefon (+49) 6131 39 3 0181
Telefax (+49) 6131 39 2 3070
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http://www.uni-mainz.de/FB/Geo/Geologie/archaeo/
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