pa1778data.pdf
pa1778data.pdf
pa1778data.pdf
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U.S. STEEL DUQUESNE WORKS<br />
HAER No. PA-115<br />
(Page 176)<br />
slag mixture consisting of four parts lime and one part fluorspar<br />
or clean sand was added. Several samples of the slag were taken<br />
in the period after the mixture was added. As the heat<br />
proceeded, the color of the slag samples taken varied between<br />
shades of brown, and contained varying amounts of manganese<br />
oxide, indicating the stage of deoxidation or levels of iron<br />
oxide being reduced. A slag sample which was decidedly brown in<br />
color meant that deoxidation was well under way. At this point a<br />
second slag mixture consisting of proportioned amounts of lime,<br />
fluorspar, sand, and coke dust was added to the bath. The<br />
addition of this mixture made the slag less vitreous thereby<br />
creating a tendency for it to slake or disintegrate. At the same<br />
time the color of the slag began to fade. Deoxidation was judged<br />
complete and preparations were made to finish the heat when a<br />
sample of the slag disintegrated upon becoming cold, while the<br />
color turned gray.<br />
The heat was finished by adding whatever alloys were<br />
required in the batch. In order to give these alloys time to<br />
thoroughly mix with the steel, a period of approximately thirty<br />
minutes was allowed to pass before the heat was tapped. After a<br />
final sample was taken to determine if the condition of the slag<br />
was satisfactory, the furnace was tapped. Tapping consisted of<br />
tilting the furnace on its rockers toward a teeming ladle set in<br />
a pit below the tapping spout on the pouring aisle of the<br />
building. A special skimmer, attached to the pouring spout of<br />
the furnace, separated the slag from the steel as it was being<br />
poured into the ladle. Subsequent to tapping, the ladle was<br />
carried over by a E.O.T. crane to the platform where the steel<br />
was teemed into ingot moulds. 1<br />
Full fledged use of the electric furnace process for melting<br />
down steel scrap did not take place at Duquesne until World War<br />
II when an alloy steel plant was built by the Defense Plant<br />
Corporation (D.P.C.). The new facility, which was part of an<br />
effort to increase production for war time needs, was designed to<br />
work in conjunction with a newly constructed heavy forging plant<br />
built by the D.P.C. at the nearby Homestead Works. Consisting<br />
of electric furnace, heat treating, and steel conditioning<br />
facilities, part of the plant was built on land occupied by the<br />
city of Duquesne's First Ward, which had been located between the<br />
upper and lower works. The electric furnace building originally<br />
contained two side door charged 70-ton furnaces and one side door<br />
35-ton capacity furnace. All of the furnaces contained a basic<br />
(magnesite brick) lining.<br />
Electric furnace alloy steelmaking at Duquesne followed the<br />
precepts of the "cold melt process." The process employed the<br />
direct arc method and was conducted in two stages. During the