The slag in question comes from a creek bed adjacent to the ruined blast
furnace stack of the Albemarle IW (S Garden, VA, USA). The furnace was built
late in 1771 and went into blast either in late 1771 or early 1772. The
furnace was blown out in May of 1772 and permanently shut down. Although the
company planned to build a finery forge, the documentary evidence indicates
that it was never finished.
The samples have been subjected to PIXE and SEM, so all I have is an elemental
analysis. The data has been normalized by weight for the oxides that might be
present. I do not know if they contain wustite or fayalite. But as they are
from a blast furnace, albeit a failed one, they shouldn't contain large
amounts of either. the wustite shown in the SEM analysis is inferred from the
elemental analysis, rather than measured.
The slag is not "normal" glassy blast furnace slag. The composition of the
slag varies considerably from sample to sample and within samples from region
to region. There are large prills of iron, numerous voids, and the
impression of charcoal can clearly be seen on the exterior. According to
Geoff Grime at Oxford it has large crystals of titanium compounds. Gerry
McDonnell's analysis (see below) also showed the presence of almost pure
titanium compounds (Ref# 10 & 19).
Albemarle PIXE Analysis (C. Swann, U. of Delaware and presented at the
International Conference on Nuclear Microprobe Technology and
Applications in Bordeaux this September)
1 Fe 1 glassy 1 matte 2 matte 3 grey 3 matte
>
> Al 0.070 1.678 2.126 1.476 2.734 2.545
>
> Si 0.469 13.852 15.935 12.626 20.939 17.004
>
> P 0.955 0.093 0.146 0.085 0.110 0.130
>
> S 0.052 0.403 0.494 0.185 0.054 0.084
>
> Cl 0.090 0.327 0.175 1.130 0.779 0.577
>
> K 0.025 2.629 2.743 2.119 3.424 2.088
>
> Ca 0.569 25.703 28.723 30.777 28.404 35.052
>
> Ti 0.250 23.624 25.637 16.455 36.974 27.316
>
> V 0.130 0.345 0.195 0.135 0.200 0.166
>
> Cr 0.153 0.069 0.083 0.068 0.081 0.081
>
> Mn 0.248 0.671 0.195 0.576 0.843 0.540
>
> Fe 96.991 30.613 23.178 34.372 5.459 14.417
Scanning Electron Microscope (SEM) Analysis
Performed at the University of Bradford (UK) by Dr. Gerry McDonell
Slag Analysis
Sample # 1 1 1 1 1 1 2
2 2 2
Slag Slag Glass Glass Xtal Xtal Bulk Bulk Bulk
Xtal
Bulk Bulk 1 2
1 2 3
Ref # 4 8 5 9 6 10
15 16 18 19
Na2O 0.9 0.7 0.6 0.6 0.7 0.1 0.8
1.5 1.5 0.0
MgO 3.0 2.9 3.5 3.1 0.6 2.5 3.7
4.1 3.3 1.4
Al2O3 5.9 5.8 8.8 6.4 0.7 0.6 5.8
6.0 5.4 0.5
SiO2 44.0 48.2 57.8 55.8 25.5 0.5 42.4 38.7
38.2 1.0
P2O5 0.0 0.3 0.3 0.0 0.0 0.0 0.0
0.1 0.0 0.0
K2O 1.4 2.1 2.4 2.1 0.2 0.1 1.5
1.2 1.2 0.1
CaO 17.3 15.7 17.8 20.5 20.2 0.4 23.6 21.1
22.4 1.1
TiO2 25.0 22.6 8.0 10.3 51.2 95.2 19.9 23.1
27.1 95.3
MnO 0.4 0.8 0.5 0.8 0.2 0.2 0.7
0.7 0.7 0.2
FeO 2.0 0.8 0.4 0.4 0.4 0.3 1.5
3.6 0.1 0.2
CoO 0.1 0.1 0.0 0.0 0.1 0.1 0.0
0.0 0.1 0.1
CuO 0.0 0.3 0.0 0.1 0.1 0.0 0.3
0.1 0.0 0.2
total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0
100.0
James H. Brothers IV
Ploquin Alain wrote:
> The first question before any discussion is: what type of slag contains
> these cast-iron prills ? Are they fayalitic, with or without wustite ? or
> are they more siliceous ? calcic? and so on. Mineralogical and/or chemical
> compositions of slag are important to know if cast-iron prills are
> consistent with them and with your furnace. We have, in west-centrum
> France, a very nice example of bloomeries (IVth C.) which were producing
> wrought iron (or steel) with fayalitic slags, but somtimes they produced
> cast-iron and steel prills with a silico-calcic slag (called in french
> "laitier". So, these furnaces were bloomeries but sometimes they were
> running as blast-furnace (addind some lime, and perhaps with higher
> temperature).
> These studies were published in Revue d'Archéométrie n°22, pp. 91-101, 1998
> (the editor made as mistake with my firstname: Anne instead of Alain !)
>
> cordialement
> Alain Ploquin
>
> Alain Ploquin
> Centre de Recherches Petrographiques et Geochimiques (UPR A9046)
> Centre National de la Recherche Scientifique
> B.P.20
> F-54501 Vandoeuvre-les-Nancy cedex
> France
> tel: 33/(O)383594245 fax: 33/(0)383511798
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