pa1778data.pdf
pa1778data.pdf
pa1778data.pdf
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U.S. STEEL DUQUESNE WORKS<br />
HAER No. PA-115<br />
(Page 166)<br />
hearth process involved the burning of a mixture of gas and air<br />
over a charge of limestone, iron ore, scrap steel, and molten pig<br />
iron contained within a rectangular, magnesite refractory brick-<br />
lined regenerative furnace. The oxygen content of the air, the<br />
limestone and the iron ore transformed the iron into steel by<br />
eliminating carbon, silicon, manganese, sulphur, and phosphorus<br />
from the molten bath by means of oxidation.<br />
The use of the open hearth process had several advantages<br />
over the acid Bessemer process. Because the process used iron<br />
ore as a oxidizing agent and because heat was applied externally,<br />
the temperature of the bath was made independent of the purifying<br />
reactions and the impurities were eliminated gradually so that<br />
the temperature and composition of the molten bath was under much<br />
better control. For the same reasons, a greater variety of raw<br />
materials could be utilized, particularly scrap which was not<br />
readily consumable in the Bessemer converter, and a greater<br />
variety of products could be made. This was particularly<br />
significant at Duquesne which became an important producer of<br />
alloy steel bars for the eastern market in the United States.<br />
Another important advantage of the basic open hearth process was<br />
the increased yield of finished steel from a given quantity of<br />
pig iron, because of lower inherent iron losses and because of<br />
the recovery of the iron content of the ore used for oxidation.<br />
Finally, the greatest advantage of the open hearth over the<br />
Bessemer process was its ability to eliminate phosphorus and<br />
sulphur from the bath. This opened up vast quantities of<br />
American iron ore deposits high in phosphorus content for use in<br />
steelmaking. 1<br />
Open Hearth Number One was located on the present site of<br />
the basic oxygen steelmaking facility. Like the Bessemer plant,<br />
its structures and equipment were laid out in such a manner as to<br />
permit a smooth and easy flow of materials. Open Hearth Number<br />
One initially consisted of a stockyard, a furnace building, a<br />
cinder yard, a skull cracker, and a mould conditioning building.<br />
The furnace building, which was the center of activity, had split<br />
level floors with the floor of the charging aisle located 9 f -0"<br />
above the floor of the pouring aisle. Twelve 50-ton capacity<br />
stationary open hearth furnaces, laid out linearly, divided the<br />
building between the charging and pouring aisles. Along the<br />
wall of the pouring aisle, opposite the furnaces, stood the<br />
teeming platform.<br />
The process began with the proportioned loading of scrap and<br />
raw materials boxes set upon flat rail cars in the stockyard<br />
which adjoined the furnace building. The proportions of scrap<br />
and raw materials used depended upon the desired grade of steel.<br />
When loading was complete, the cars were run along a narrow gauge