pa1778data.pdf

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U.S. STEEL DUQUESNE WORKS
HAER No. PA-115
(Page 103)
furnace's dust catcher to the bottom of one of the 15*-0"
diameter x 60'-0" high gas conditioning towers where three banks
of water sprays cooled the gas to 350° as it rose up the tower.
From the top of the tower the gas was taken by means of a 3'-6"
downcomer into the top of the unit's electrical precipitator.
Along the top inside portion of the precipitator, oil-immersed,
tube-type rectifiers ionized the incoming gas. The charged
particles in the gas were subsequently attracted to a series of
electrodes composed of 3/16" square twisted steel rods which were
suspended from an insulated high tension framework located just
below the rectifiers. Particles which adhered to the electrodes
were dropped to collecting hoppers located underneath the
precipitator with the help of magnetic impulse rappers while the
cleaned gas was taken out through a 5'-0 M diameter discharge line
leading to a clean gas manifold supplying the boilers.
The light and fluffy flue dust was released from the bottom
of the collecting hopper by means of a star valve into a screw
conveyor which led directly to the unit's 2'-6" diameter x 20'-0"
long rotary kiln. After oxidation, the dust, which increased in
bulk density from twelve to thirty pounds per cubic foot, was
discharged from the kiln into a water jacketed mixer where water
was added to agglomerate and cool the dust. An enclosed 18" belt
conveyor took the partially wetted dust from the primary mixer to
bucket elevators which supplied two large, batch-type, mix-
mullers where more water was added and mulled into the dust in
order to attain the proper consistency for briquetting. The 2" x
2" pillow shaped briquettes were produced by feeding the batch
from the final mix-mullers through the die rolls of two
briquetting presses operating under forty tons of pressure. Upon
pressing, the briquettes were taken by endless chain bucket
conveyors to overhead storage bins.
The installation of the ferromanganese gas cleaning system
at Duquesne marked the beginning of a transition period with
respect to changes and additions to the combustion air production
and delivery system at the blast furnace plant. On one hand, the
construction of the system allowed plant officials to make blast
furnace number three ready for ferromanganese production,
doubling the plant's capacity. The addition of the system, then,
could be seen as constituting a continuation of the tradition
whereby change was directly related to increased productivity.
On the other hand, the limitations of the new gas cleaning system
underscored the increasing influence which local, state, and
federal lawmakers had over iron and steel manufacturing processes
with regard to the implementation of community wide environmental
standards. Prior to this time corporate officials authorized
projects like the ferromanganese gas cleaning system only if the
flue dust could be recycled into the productive system, thereby