pa1778data.pdf

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