pa1778data.pdf

U.S. STEEL DUQUESNE WORKS
HAER No. PA-115
(Page 72)
The process by which ferromanganese was delivered also
substantially upgraded industry-wide practice albeit in a more
gradual manner during this period. Initially the molten product
was tapped from the furnace in the same way as basic iron. After
tapping, the 35-ton ferromanganese ladle cars were run over to
the pig casting machine where they were cast in the normal
manner. The brittle nature of the solidified product, however,
caused the pigs to break up as they dropped from the mold chain.
Consequently, there was a considerable loss in "fines" or small
pieces of the product chipped from the pigs. In an effort to
offset this loss, plant officials, emulating the practice used at
the Clairton and Isabella blast furnace plants, switched in
January of 1954 to the car casting technique. The former open
hearth scrap preparation building, located at the extreme
southern end of the plant, was converted into a car preparation
facility so that the 9'-6" wide x 41*-0" long x 2'-0" deep
refractory brick lined cars could be prepared for casting by
applying a protective slurry to its deck and side plates. At
first the slurry was applied by hand using the bucket and broom
technique, a process which took one hour to complete. This time
was cut to five minutes when application of the slurry by air
hose was introduced shortly thereafter.
In order to tap molten ferromanganese from the furnace into
the casting cars, special cast iron runners had to be fabricated
for use in the cast house. Unlike 35 ton ladles, which were 9'-
1" deep, the casting cars were quite shallow. Moreover, the
molten material was cast only 8" deep across the length of the
car. Consequently, the special runners were hung from the end of
each cast house runner at a 45° angle to a point l"-0" above the
casting car so as to prevent the molten material from splashing
over its sides. Once tapped, the cars were run over to the car
preparation building where the product was allowed to cool.
Initially allowed to cool in contact with the air, the practice
was later changed when a multi-jet spray water unit was installed
to continuously quench the product. As a result, the elapsed
time from casting to unloading was reduced from sixty hours to
thirty hours without harming the physical properties of the
material.
The casting cars were initially unloaded by methods which
had been practiced for many years throughout the industry. Men
wielding twenty-two pound sledge hammers and crow bars attacked
the solidified product until it was broken up to a point where
chunks of it could be unloaded by hand or by overhead crane to a
storage pile. The arduous, hazardous, and time consuming nature
of this approach prompted efforts to experiment with different
forms of unloading. A solution was found when a mobile excavator
was rented to explore the possibility of mechanical unloading.