pa1778data.pdf
pa1778data.pdf
pa1778data.pdf
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U.S. STEEL DUQUESNE WORKS<br />
HAER No. PA-115<br />
(Page 102)<br />
of the original gas scrubbers installed in 1908. A more<br />
significance industry-wide innovation was the installation of a<br />
new ferromanganese gas cleaning system in 1953. Begun in 1949 at<br />
blast furnace number two, the production of ferromanganese<br />
generated waste gases with qualities much different than those<br />
produced in furnaces on basic iron. The temperature of the gas<br />
(750° F.), for example, was nearly double the temperature at<br />
which gas from basic iron production left the furnace. Second,<br />
after leaving the dust catcher, the quantity of fine entrained<br />
particulate (about eight grains per cubic foot) was also double<br />
that contained in the flue gas emanating from furnaces on basic<br />
iron production. Consequently, it was impossible to clean all of<br />
the gas flowing from a furnace on ferromanganese by conventional<br />
methods. This meant that much of the fume had to be emitted into<br />
the atmosphere through bleeder stacks located at the top of the<br />
furnace. Third, the floury composition of the flue dust from<br />
ferromanganese furnaces made it difficult to store as it would<br />
become air-borne in the slightest breeze. Compounding the<br />
problems associated with ferromanganese production was the<br />
pyrophoric nature of the flue dust which made it susceptible to<br />
spontaneous combustion upon exposure to the atmosphere.<br />
Efforts to find solutions to these practical problems were<br />
further influenced by smoke control legislation passed by<br />
Allegheny County in 1949. Among the most stringent in the nation<br />
for its time, the ordinance limited flue dust emissions to .5 or<br />
less pounds per 1,000 pounds of gas produced, mandating that 85<br />
percent of all industrial gas produced be removed.<br />
Over the years several cleaning methods and types of<br />
equipment were tried at Duquesne without appreciable success.<br />
For example, ferromanganese gas was run through an electrical<br />
precipitator after it had passed through the plant's conventional<br />
gas cleaning equipment. This experiment lasted less than a year<br />
as the great quantity of dust generated in ferromanganese<br />
production completely clogged up the precipitator at frequent<br />
intervals. Finally, after years of research conducted by the<br />
United States Steel Corporation in conjunction with engineers<br />
from the Research Corporation at the Isabella furnace plant in<br />
Etna, Pa., a workable solution to the cleaning problem was found.<br />
It resulted in the installation of the industry's first cleaning<br />
plant devoted solely to ferromanganese gas at the Duquesne Works.<br />
The plant consisted of five parallel units, each composed of a<br />
gas conditioning tower, an electrical precipitator, a screw<br />
conveyor-fed rotary kiln, and a continuous mixer. Two additional<br />
bucket conveyor-fed intensive mixers served all five units before<br />
discharging the flue dust into a briquetting press.<br />
The process began with the transfer of the flue gas from the