pa1778data.pdf

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degrees F to 85 degrees F.
U.S. STEEL DUQUESNE WORKS
HAER No. PA-115
(Page 237)
The cold well basin is located at the eastern end of the
cooling tower. Four Worthington 150 hp motor-powered process
water pumps, each with a capacity of 3,000 gpm are located on a
platform above the cold well. These pumps are used to return
process water to the primary and bar mills.
Installation date: 1981.
4. Thickener: The 25' diameter x 15'-9" high, 50,000 gallon
thickener was constructed by the Chicago Bridge and Iron Company.
It is located just south of the Process Pump Building. Solids
from the clarifier and the spent backwash tank were concentrated
in the gravity thickener by means of a mechanically operated rake
arm which was raised and lowered in the thickener tank. The
flows were introduced into the thickener tank through a trough
which discharged into the center feed well. Sludge was received
into the thickener at concentrations ranging from 5 percent to 20
percent solids by weight. The sludge was concentrated to
approximately 3 0 percent solids by weight in the thickener. The
thickener also contained a polymer feed system to add polymer to
the thickener in order to enhance settling, if required. The
overflow from the thickener flowed by gravity to the clarifier.
Thickened sludge was pumped by one of two constant speed
horizontal, centrifugal thickener underflow sludge pumps, located
beneath the thickener, to the vacuum filters.
Installation date: 1981.
5. Vacuum Filters and Vacuum Pumps: Two Dorr-Oliver, 12'
diameter x 12' long cloth covered rotary vacuum drum filter
assemblies are laid out alongside each other on the second floor
of the Process Building at its southern end. These are serviced
by two Dorr-Oliver, Nash Type CL vacuum pumps which are located
just to the west on the second floor. The vacuum filters,
operating in the same way as those used at the blast furnace and
basic oxygen plants, dewatered the thickened sludge. After
vacuum filtration, the filtered sludge cake was discharged
through two sludge cake chutes (one located at each vacuum
filter) into the sludge storage area. Periodically, the
dewatered sludge is removed from this area by a front-end loader
and trucked to a final disposal site.
Installation date: 1981.
HISTORY
The 22" Bar Mill was originally constructed in 1906. Over
the years a number of changes and additions have been made to
both the physical complex and the equipment within the complex.
For example, the original steam-engines which drove the 28" and