pa1778data.pdf
pa1778data.pdf
pa1778data.pdf
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construction carbon and alloy steels.<br />
U.S. STEEL DUQUESNE WORKS<br />
HAER NO. PA-115<br />
(Page 204)<br />
The process essentially involved blowing 1500 cfm of gaseous<br />
oxygen under a pressure of 150 psi down through a lance set just<br />
above a proportioned charge of scrap steel (up to 3 0% of the<br />
charge), molten iron, and fluxing materials contained within a<br />
barrel shaped, basic (magnesite brick) lined, concentric furnace<br />
with an open top. The exothermic reaction between the oxygen and<br />
the metallic bath converted the iron into steel by eliminating<br />
carbon, silicon, manganese, sulphur, and phosphorus through<br />
oxidation. An average blow lasted approximately twenty-two<br />
minutes. 5<br />
As evidenced by Duquesne's quick conversion to exclusive use<br />
of the process and by the short period required to make a heat,<br />
basic oxygen combined the versatility of the open hearth process<br />
with the speed of the Bessemer steelmaking process. This was due<br />
to three factors. First, the successful adaptation of the<br />
Linde/Frankel process, which separated oxygen from air, enabled<br />
steelmakers to develop a pneumatic system capable of producing<br />
much larger tonnages of steel per heat, in approximately the same<br />
amount of time than was possible under Bessemer production.<br />
Because of the relatively shorter heat times, moreover, the basic<br />
oxygen process produced tonnages comparable to the open hearth<br />
process while employing significantly fewer furnaces. Second,<br />
the use of a basic lining in the furnace made it possible to<br />
eliminate phosphorus from the charge of molten iron because it<br />
allowed for the addition of basic fluxing materials during the<br />
process. Finally, increased knowledge about the correct<br />
proportions of materials to be charged into the furnace relative<br />
to the metallurgical requirements of the steel to be made in the<br />
heat combined with improved instrumentation for temperature<br />
measurement to create a situation where a great variety of steels<br />
could be made while maintaining temperature control.<br />
Laid out on a north-south axis, Duquesne's basic oxygen<br />
steelmaking plant was located at an equal distance between the<br />
blast furnace plant and primary rolling mills. All charging<br />
materials flowed to the oxygen furnaces from a southerly<br />
direction. When the plant first went into operation, the process<br />
began by charging the furnace with scrap steel, followed by<br />
molten iron. Fluxing materials were added shortly after the heat<br />
had begun. The composition, exact weight, and temperature of the<br />
raw materials were determined by a computer located in the<br />
production planning office according to the specifications of the<br />
steel to be made in the heat.<br />
A twenty-four hour supply of scrap, stored in gondola rail<br />
cars, was located in the scrap yard at the southern end of the