Dear Michael
> The second type of furnace, produce results in the slags which are high in
> alumina levels (12-16%) in both furnace and tap slag, iron levels between
> 23-53% and calcium levels of 5-6%. The alumina is not provided from the
> ore, which has been analysed and is hematite.
I would be rather suspicious of this statement. The East Midlands
has many ore sources, but these are dominantly of siderite or
goethite rich ores. On roasting these may become haematitic, but
most of them have appreciable alumina and lime. They are not
haematite ores in the sense of those from Cumbria or the Bristol
Channel. The ore sources are sedimentary and therefore typically
rich in clay. In some instances early working segregated the
weathering crusts for preferential smelting - but these will still not
be alumina-free.
What is the morphology of your high alumina slags? Are you
certain they are from smelting? The analyses you quote would
bracket typical early smithing slags where a clay-lined hearth has
been used.
Best wishes
Tim
Dr Tim Young
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