pa1778data.pdf
pa1778data.pdf
pa1778data.pdf
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U.S. STEEL DUQUESNE WORKS<br />
HAER No. PA-115<br />
(Page 160)<br />
charging floor, tilted in the direction of the charging aisle and<br />
the pouring aisle. Set directly over the mouth of the converter<br />
on the scrapping floor were a series of bins containing scrap<br />
steel segregated by its metallurgical composition. On the<br />
charging side of the vessels, the ground floor extended under the<br />
converters and offered space for the removal of converter bottoms<br />
and slag.<br />
In plants such as the one at Duquesne, the process began<br />
with the removal and replacement of the converter bottom if it<br />
required repair. First, the steel plate constructed shell or<br />
wind box which covered the tuyeres was removed. Afterward, a<br />
small truck riding on rails was run out of the bottom house and<br />
positioned under the converter. Once positioned, the truck's<br />
hydraulic powered lifting table was raised up to the level of the<br />
bottom and the keys fastening the bottom to the converter were<br />
knocked out thereby allowing it to drop onto the table. After<br />
the table descended to its original position, the truck was run<br />
back to the bottom house where a crane removed the deteriorated<br />
bottom and replaced it with a reconstructed one. The procedure<br />
was then reversed and the bottom was replaced on the converter.<br />
The decayed bottom was repaired by replacing its tuyeres and<br />
relining it with refractory brick before placing it in one of the<br />
bottom house's drying ovens where the brick was carefully dried<br />
and baked for a period of 48 hours.<br />
With the replacement of its bottom, the converter was ready<br />
to be charged. A critical element of the charging process was<br />
determining the proper amount of cold scrap and hot metal to be<br />
charged into the converter. This was regulated by the amount of<br />
and grade of steel required at the blooming mill. Important<br />
considerations in meeting the rolling requirements were the<br />
composition of the molten pig iron to be charged and the heat<br />
requirements of the blow. Molten iron, containing levels of<br />
silicon and manganese which could not be sufficiently removed by<br />
oxidization during the converter blow, was diluted by a<br />
proportioned charge of steel scrap with low levels of those<br />
elements. Because the process was dependent on heat generated by<br />
the oxidation of the impurities, a significant portion of the<br />
iron could be lost through oxidation if the heat generated by the<br />
blow exceeded the temperature required to keep the iron molten.<br />
The addition of a proportioned cold scrap charge, then, also<br />
performed the function of controlling the temperature of the<br />
heat. When the blower determined the proper mixture of molten<br />
pig iron and cold scrap, he sent an order to the cupola house for<br />
a certain weight of molten pig iron.<br />
After the iron had been tapped from the cupola into a ladle<br />
car and weighed, it was run over to the charging floor of the