i STEAM COAL - Clpdigital.org
i STEAM COAL - Clpdigital.org
i STEAM COAL - Clpdigital.org
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34 THE <strong>COAL</strong> TRADE BULLETIN.<br />
\ AIR COMPRESSOR PLANT OF THE HOMESTAKE MINING COMPANY.<br />
Probably twenty localities, scattered over all<br />
parts of the world, claim for some one of their<br />
producing mines the distinction of being "the<br />
greatest gold mine in the world." Perhaps no<br />
where are facts so hard to obtain as in mining<br />
operations. Yet the passing years have a way of<br />
sifting facts from fancies, and the highest authorities<br />
to-day unite in assigning to the great Homestake<br />
mine, at Lead. South Dakota, the first place<br />
among the gold mines of the world. Its monthly<br />
yield of the yellow metal averages in the neighborhood<br />
of $425,000, the value of over 2.000 ounces<br />
of fine gold. This is secured by the treatment of<br />
about 125.000 tons of ore per month.<br />
A singular, and at first thought inexplicable,<br />
fact is that the Homestake, while unquestionably<br />
the world's richest gold producer, is relatively one<br />
of the poorest mines. The average ore values are<br />
only about $3.60 per ton, while mining and treatment<br />
charges, run about $2.40 per ton. The explanation<br />
of the mine's value lies in the enormous<br />
tonnage and in the cheap operative and productive<br />
charges. The secret of low charges lies in<br />
the adoption of the latest methods, the best machinery<br />
and a careful consideration of the small<br />
economies. The handling of immense quantities<br />
of ore by the most refined machine methods has<br />
made this "low grade" property the greatest bonanza<br />
in the world. The success of this great<br />
enterprise is a remarkable example of what modern<br />
productive methods can bring about, and a description<br />
of a part of the equipment will be of<br />
interest. Compressed air has long been recognized<br />
as a powerful factor in economical mine<br />
operation and in the Homestake mine its possi<br />
One'of the Air Compressor Plants of the Homestake Mine.<br />
bilities have been developed to the utmost.<br />
As is eminently fitting, this greatest mine in<br />
the world has in its power plant the largest air<br />
compressor in the world, and this giant must receive<br />
the first mention in the list of machines<br />
on the Homestake lode. It is located at the Ellison<br />
shaft and is a cross compound condensing<br />
two-stage Corliss machine, built by the Ingersoll-<br />
Sergeant Drill Co. of New York. The high and<br />
low pressure steam cylinders have a diameter of<br />
32 and 60 inches, respectively, the air cylinders<br />
are 52% and 32% inches in diameter, and the<br />
stroke is 72 inches. At the rated speed of 50<br />
R. P. M. the free air capacity is 9,000 cubic feet<br />
per minute, this volume being sufficient, under<br />
average conditions of mine work, to operate 125<br />
rock drills. The steam pressure is about 130<br />
pounds. The exhaust steam is received by a<br />
Wheeler surface condenser, in connection with a<br />
cooling tower. The well known Ingersoll-Sergeant<br />
piston inlet valve is used on both high and<br />
low pressure air cylinders, between which a horizontal<br />
inter-cooler is placed in the air circuit.<br />
The total weight of this huge compressor with its<br />
accessories, is about 300 tons. It is placed beside<br />
the great Ellison hoist, the mountain being<br />
blasted out to make space for the engine room.<br />
The output of this great machine is used exclusively<br />
for [operating machine drills in the<br />
underground workings. It is assisted by two<br />
smaller machines, built by the same maker and<br />
both of the Corliss type, with piston inlet valve.<br />
One of these machines, located at what is known<br />
as the Old Abe shaft, is a duplex machine, with<br />
steam cylinders 24 inches in diameter, air cylin-<br />
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