pa1778data.pdf

U.S. STEEL DUQUESNE WORKS
HAER No. PA-115
(Page 160)
charging floor, tilted in the direction of the charging aisle and
the pouring aisle. Set directly over the mouth of the converter
on the scrapping floor were a series of bins containing scrap
steel segregated by its metallurgical composition. On the
charging side of the vessels, the ground floor extended under the
converters and offered space for the removal of converter bottoms
and slag.
In plants such as the one at Duquesne, the process began
with the removal and replacement of the converter bottom if it
required repair. First, the steel plate constructed shell or
wind box which covered the tuyeres was removed. Afterward, a
small truck riding on rails was run out of the bottom house and
positioned under the converter. Once positioned, the truck's
hydraulic powered lifting table was raised up to the level of the
bottom and the keys fastening the bottom to the converter were
knocked out thereby allowing it to drop onto the table. After
the table descended to its original position, the truck was run
back to the bottom house where a crane removed the deteriorated
bottom and replaced it with a reconstructed one. The procedure
was then reversed and the bottom was replaced on the converter.
The decayed bottom was repaired by replacing its tuyeres and
relining it with refractory brick before placing it in one of the
bottom house's drying ovens where the brick was carefully dried
and baked for a period of 48 hours.
With the replacement of its bottom, the converter was ready
to be charged. A critical element of the charging process was
determining the proper amount of cold scrap and hot metal to be
charged into the converter. This was regulated by the amount of
and grade of steel required at the blooming mill. Important
considerations in meeting the rolling requirements were the
composition of the molten pig iron to be charged and the heat
requirements of the blow. Molten iron, containing levels of
silicon and manganese which could not be sufficiently removed by
oxidization during the converter blow, was diluted by a
proportioned charge of steel scrap with low levels of those
elements. Because the process was dependent on heat generated by
the oxidation of the impurities, a significant portion of the
iron could be lost through oxidation if the heat generated by the
blow exceeded the temperature required to keep the iron molten.
The addition of a proportioned cold scrap charge, then, also
performed the function of controlling the temperature of the
heat. When the blower determined the proper mixture of molten
pig iron and cold scrap, he sent an order to the cupola house for
a certain weight of molten pig iron.
After the iron had been tapped from the cupola into a ladle
car and weighed, it was run over to the charging floor of the