pa1778data.pdf

U.S. STEEL DUQUESNE WORKS
HAER NO. PA-115
(Page 71)
number six, were also rebuilt during this period. Conforming to
new ideas about the relationship between productive capacity and
the design of furnace lines, the rebuild resulted in furnaces
with larger hearth diameters (17'-0" for all rebuilt furnaces but
number two which was lS'-O") and shorter bosh heights. When,
however, it was found that the furnace rebuilding project
increased annual capacity for the entire plant by only 6,600 tons
over the pre-reconstruction figure of 1,035,000 tons, each of the
six furnaces were relined in 1928 and 1929. The relining, which
slightly increased the bosh diameter of each furnace, expanded
annual capacity to 1,319,200 tons. 4
Although furnace linings normally wore out every four or
five years, the slack demand for iron and steel products during
the depression years meant that the furnaces were hardly in use
until the first half of the 1940s. Consequently, no further
additions or modifications were made to the iron production and
delivery facilities until after World War II when all of the
furnaces were relined and ferromanganese was added to the plant's
product mix at blast furnace number two in 1949. The relining
resulted in larger hearth diameters for each furnace, thereby
increasing annual plant capacity to 1,451,400 tons, of which
105,200 tons were devoted to the production of ferromanganese.
The steps involved in the production and delivery of
ferromanganese necessitated significant changes to the blast
furnace plant between 1949 and 1956. In the process of making
these changes, many of which began as on site improvisations
seeking ways to upgrade old methods, the Duquesne Works became
the most modern ferromanganese production and delivery facility
of the time.
A common alloy of steel, ferromanganese was produced by
charging four parts manganese ore to one part iron ore into the
top of the blast furnace along with coke and limestone.
Moreover, because of the high melting point of the manganese ore,
the production of ferromanganese required twice as much coke as
the production of basic iron which, in turn, considerably
increased temperatures inside of the furnace. As a result, it
was normal practice to put a furnace on ferromanganese production
during the last year of its scheduled campaign (i.e. when its
lining was about ready to give out). When the decision to
produce ferromanganese at Duquesne was made, however, it was
decided to abandon normal practice by adding special features to
the furnaces used for this purpose. Consequently, blast furnace
number two, and, in 1953, blast furnace number three, were fitted
with nine extra rows of cooling plates and new water sprays
inside the furnace before they were put on "ferro".