Albemarle Iron Works (1771–1772): Why didthis operation fail?

James H. Brothers IV a, Geoff W. Grime b, Charles P. Swann c,*

a Department of Anthropology, College of William and Mary, Williamsburg, VA 23187, USAb Department of Materials, University of Oxford, Parks Road, Oxford, OXC1 3PH, UK

c Bartol Research Institute, University of Delaware, Newark, DE 19716, USA

Abstract

In December of 1770 the Albemarle Iron Works, Albemarle County, Virginia, USA was formed to build a cold blast

furnace for producing cast iron. This furnace was put into operation in September of 1771 but was closed permanently

in June of 1772; no usable iron was ever produced. The reason for this failure is not clear, but it has been suggested that

the cause was the use titaniferous iron ore. The presence of high Ti would result in a very high viscosity slag, which in

turn would not allow for the separation of the iron from the slag and, thereby, slow down the operation of the furnace.

Slag, recently taken from the site, has been analyzed by both PIXE and SEM, and the results confirm the high Ti

content. Another indication that the furnace was having difficulties was that the slag was not typical glassy slag.

Furthermore the iron prills entrapped in the slag showed a high phosphorus content which would result in an iron too

brittle for practical use. � 2002 Elsevier Science B.V. All rights reserved.

PACS: 81.05.Bx

Keywords: PIXE; Archaeometry; Cold blast furnace; Iron slag; Early american

1. Introduction

From the very beginning the Albemarle IronWorks in Virginia, USA, was in trouble because ofmanagement problems. The company was formedon 28 December 1770 with five partners, one ofwhom, John Wilkinson, was appointed as theworks manager. On 18 July 1771, John Swan tookover the position only to be replaced on 17 Sep-tember by William Twadle. There is evidence that

the furnace was completed early in 1772, but thiscannot be verified because most of the records ofthe company were lost in a fire at John Wilkinson’shouse following the demise of the operation. ByJune the operation was declared a failure and shutdown by the partners, having never produced anyusable iron. At that time the cause of this failurewas not clear, but certainly the problems with themanagement were a contributing factor. Overmany years following, attempts were made to re-vive the operation, but to no avail. It was not until1882 that an analysis of ore from the Betsy MartinMine in 1882 revealed a high titanium content [1].In 1977 [2] it was established that this mine con-tained ilmenite (FeTiO3) and apatite (a mineral

Nuclear Instruments and Methods in Physics Research B 189 (2002) 340–343

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*Corresponding author. Tel: +1-302-831-1279; fax: +1-302-

831-1843.

E-mail address: swann@bartol.udel.ed (C.P. Swann).

0168-583X/02/$ - see front matter � 2002 Elsevier Science B.V. All rights reserved.

PII: S0168 -583X(01)01083 -7

containing phosphorus); in addition a large rareearth component was observed. Both of theseminerals would result in poor iron production, andit is quite certain that the ore used in the Able-marle works came from the Martin Mine. It wasthe intent of the present study to demonstrateconclusively that the slag in the area of furnace didindeed contain high levels of both titanium andphosphorus.

2. Experimental procedures

Slag samples were collected from the site of theAlbemarle Iron Works in February 1999. Just inappearance, as is apparent in Fig. 1, these sampleswere not of good quality; they were very non-uniform with mottled gray areas, glassy regionsand, and in one case, a fairly large iron prill visibleto the naked eye was present. This variation inappearance alone suggests a distinctly poor oper-ation of the furnace.The different regions of these slags as indicated

above were then subjected to analysis using the inair/helium proton-induced X-ray emission (PIXE)technique and scanning nuclear microprobe (NMP)at Oxford. The first of these methods of ana-

lyses (PIXE) has been well described in the litera-ture z[3,4] and only aspects pertinent to this studywill be mentioned here. Two different sets of mea-surements were made on the three regions char-acterized as glassy, mottled gray and matte. In thefirst set the only measurements made were at aproton energy of 1.3 MeV with a flow of heliumencompassing the region of the beam extractiontip, the sample and the entrance window of theSi(Li) X-ray detector. During the measurementsthe sample was moved several times in order to geta reasonable average of the elemental components,the beam diameter at the sample was about 500lm and the elements observed were in the mag-nesium to copper region of the periodic table. Theintent of this measurement was to establish thatthe slag was indeed very high in titanium. Thesecond set of measurements were undertaken at alater date with the purpose of looking for heavierelements which could help in identifying the typeof ore used in the furnace. The beam energy wasraised to 2.0 MeV and a filter of vanadium backedby aluminum was placed in front of the detectorwindow; with this condition the elements fromiron to zirconium were observed. The OxfordScanning Nuclear Microprobe system has beenwell described in the literature [5]. Both PIXE

Fig. 1. Photograph of three slag samples, the scale at the bottom is 18 cm long; the texture and shading are very non-uniform.

J.H. Brothers IV et al. / Nucl. Instr. and Meth. in Phys. Res. B 189 (2002) 340–343 341

and RBS measurements were performed simulta-neously, using protons. This arrangement allowsfor the observation of the elements carbon throughiron.

3. Results

Results of the micro-PIXE elemental maps foriron, calcium and titanium in the slag are shownin Fig. 2. The approximate composition is 28%,22% and 13% (by weight) of the silicon, calcium

and titanium oxides, respectively, and the carboncontent of the prill is estimated to be about 5%.This carbon content is consistent with the Albe-marle furnace having produced cast iron. All ofthe results for the two separate PIXE measure-ments are given in Table 1, wherein the elements,except for iron, are expressed as oxides; the iron onthe basis of the NMP scans is essentially all in theform of prills. The PIXE analysis of the large prillreferred to above is given in Table 1. Carbon, ofcourse, is not observed in these PIXE measure-ments. Several things are quite clear from theseresults. First and foremost is the very high tita-nium content; second is the moderately highphosphorus content; third is the presence of themodest level of yttrium which is indicative of thepresence of rare earths.

4. Discussion

It appears from the results given above that theore used in the initial and fatal operation of theAlbemarle Iron Works was from the Martin mineand contained both ilmenite (FeTiO3) and apatite(calcium flurophosphate). Within the furnace theilmenite decomposes rapidly into FeO and TiO2

(titania); this latter is chemically similar to silicaexcept that it is even harder to reduce at the tem-peratures possible in a cold blast furnace. Conse-quently, essentially all of the titania would beincorporated into the slag. The data in tablesconfirm this fact in that titanium constitutes lessthan 1% of the iron metal but up to 40% of theslag. This small quantity of titanium would havelittle discernable effect on cast iron whereas thetitanium remaining in the slag has serious conse-quence. Under the reducing conditions found in acold blast furnace, even a small amount of tita-nium in the ore has the effect of raising the meltingtemperature of the slag and, in fact, at the level oftitanium observed, could well have prevented theformation of a fully molten slag [6–8]. This wouldimpede the flow of heat and carbon monoxide upthe stack and thereby would have slowed the de-scent of the charge, the ore, charcoal and the flux(limestone). As a result of the very viscous slag, the

Fig. 2. Micro-PIXE elemental maps of iron slag; map size

400� 400 lm2.

342 J.H. Brothers IV et al. / Nucl. Instr. and Meth. in Phys. Res. B 189 (2002) 340–343

cast iron would end up as prills entrapped in theslag.

5. Conclusion

As stated earlier and shown in Fig. 1, the slagsamples studied were of poor quality, fitting wellwith the process given above. It is clear that thehigh titanium content of the ore resulted in thefailure of operation. Even had this problem withthe titaniferous ore been recognized at the time,the resulting cast iron would not have been mar-ketable because of the high phosphorus contentwhich would have resulted in a cold short (verybrittle) material. This high phosphorus could bethe result of the presence of apatite in the ore or ofa phosphate in the limestone flux. Finally, themoderate level of yttrium in the ore is suggestive ofa significant rare earth component which is con-

sistent with the findings for the ore from the BetsyMartin Mine.

References

[1] W.M. Bowron, American Industrial Mining Engineers XI

(May 1882 to February 1883) 159.

[2] T.V. Dagenhardt Jr., G.L. Maddox, Rocks and Minerals

50 (1977) 360.

[3] C.P. Swann, S.J. Fleming, Scanning Microscopy 2 (1988)

197.

[4] H.R. Schenck, R. Knox Jr., MASCA Journal 3 (5) (1985)

139.

[5] G.W. Grime, M. Dawson, M.A. Marsh, I.C. MacAathur, F.

Watt, Nucl. Instr. and Meth. B 54 (1991) 52.

[6] H.A. Fine, S. Arca, Ironmaking and Steelmaking 7 (940)

(1980) 160.

[7] T. Rosenqvist, Principles of Extractive Metallurgy, Mc-

Graw-Hill, New York, 1983.

[8] Y. Morizane, B. Ozturk, R.J. Fruehan, Metal. and Mat.

Trans. B 30B (1999) 29.

Table 1

Measured composition by PIXE of slag samples and iron prill (wt.%)

Sample Glassy Matte Grey Iron prill

(1)a (2)a (1a) (1b) (1c) (2) (1) (2)

MgO 0.76 1.29 1.04 0.92 1.39 1.14 0.96 1.54 Mg <0.01

Al2O3 2.16 3.84 2.64 1.97 2.99 2.98 3.11 4.18 Al 0.07

SiO2 20.37 32.47 22.48 19.22 23.15 22.68 27.11 36.36 Si 0.47

P2O5 <0.15 0.17 <0.23 <0.13 <0.20 <0.16 <0.15 <0.21 P 0.96

SO3 0.69 0.16 0.81 0.33 0.12 0.08 0.08 0.21 S <0.05

K2O 2.16 2.06 2.17 1.79 1.59 2.59 2.48 2.49 K <0.03

CaO 24.69 18.65 26.52 30.62 30.18 29.78 24.06 21.43 Ca 0.15

TiO2 27.07 35.86 28.27 19.54 28.15 27.99 37.35 36.34 Ti 0.25

MnO 0.60 0.51 0.17 0.54 0.45 0.37 0.82 0.55 Mn 0.03

Fe 20.89 6.15 15.39 24.40 9.17 11.28 3.30 3.21 Fe 96.99

CuO 0.117 <0.006 0.12 0.17 0.17 0.013 0.14 <0.014ZnO 0.015 0.015 <0.022

Rb2O <0.001 0.019 0.018

SrO 0.090 0.192 0.156

Y2O3 0.102 0.133 0.126

ZrO2 0.241 0.194 0.157

a (1) Data of 06/22/00, (2) data of 02/14 & 15/01: slags as oxides, prill as metals typical errors – MgO � 10%; SiO2 � 0:4%; TiO2 and

Fe � 0:5%; SrO, Y2O3 and ZrO2 � 10–15%.

J.H. Brothers IV et al. / Nucl. Instr. and Meth. in Phys. Res. B 189 (2002) 340–343 343