The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1922-01-05

zOna the rock temperature was 9OoF.
at a point 600 1T. below the surface
in a deposit in another Arizona dis
trict, the rock-temperature 600 It. be-
low the surface was but 7O'F. The
temperature of coal in place in coal
mines in the United States is rarely
above 70'F., and is generally much
less Recent magazine articles give
the rock temperature of the Kolar
goldfield in India at 11S'F at a point
61OO IT, below tine surface, and 97'F.
at the 40OO-ft. level of the st. John
Del Rey mine in Brazil; it is calcu-
lated that at the SCOTT. level of the
City Deep mine in South Africa the
rock temperature will be about 97'F.
Rock may vary at the
same depth in different kinds of ma
terial: copper sulphide ore with
quartz gangue may have rock tenn
perature several degrees higher than
zinc-sulphide ore in quartz gangue in
parallel vein about 200 IT. distant
Water standing still or flowing in
mines readily communicates its tenn
perature to the surrounding air Water
dripping through the air quickly brings
the air to the temperature of the water.
which is generally the same as that of
the surrounding rock. Mining engi-
neers take advantage of the use of
water-sprays to cool the air but man
ayers fear that water-sprays will
cause excessive humidity, forgetting
that mines generally have the humid
ity anyway, and that if the air can be
cooled to rs f. or below. and given a
slight movement, the high humidity is
not harmful Recent experimental
work in South Africa showed that men
in stagnant air with a humidity of $50
and temperature of 81 f. did more
work after fan was put in operation
to move the air; high humidity is not
particularly detrimental Air passing
through fans frequently has its dry
bulb temperature increased. In one
instance, the air from an underground
fan delivering over 10000 Gu. #. per
minute had SoF. higher temperature at
delivery than at intake. these points
being less than so IT apart. Similarly,
small canvas-pipe units, used under
ground for local ventilation. frequently
deliver air that is several degrees
higher in temperature than that of the
air at the intake Small electrically
driven fans, with galvanized iron or
canvas tubing, are being introduced
into metal mines to carry air to dead
ends The galvanized iron has the ad-
vantage of permitting the reversal of
air currents-to pull smoke out after
blasting. then to force air to workers;
moreover it dose not decay as fast as
the canvas. The canvas tubing must
be used only in forcing air to the face;
it's advantages lie in low first cost
readiness of installation and removal
nexibility in conforming to bends or
turns, and ease of repairs. Moreover
because of readiness of installation
and removal, the canvas tubing can
be brought close to the working face
at ordinary times and easily removed
prior to blasting Either method read
lily permits of placing from 500 to 1000
Gu. IT. of air per minute at the working
face for a comparatively small cost
Compressed air from the end of hose
is used to a great extent to ventilate
the working faces in metal mines; its
temperature rarely varies much over,
two or three degrees from the temper
AZURE of the rock and air of the work.
ing face Such a method is useless for
the removal OF smoke or gas it pro-
vides comparatively little pure air, and
ensures little reduction of tempera-
ture. The use of electrical machinery
causes considerable in
crease of temperature.
In the event of a fire in a metal
mine, the lack of an efficient ventila-
ton system may be disastrous. There
should be a definite system of air
splits, so that fire in one place may
cot necessarily fill the entire mine
With poisonous gas. There should be
/ system of doors, so that the shaft
II any part of the mine may be readily
solated in case of fire. The lining of
shafts with concrete will reduce fric-
ion to such an extent that additional
iir can be handled by the same eXpen-
liture of power. 1t is also found that
ubing the same amount of air will be
delivered with a saving of one-quarter
0 third of the power by the use
# fans with one-half to two thirds the
width of the standard fans. If the lin
ng is done by the use of "gunite" it
.lso serves as -proofing. The ex-
,ense of establishing a ventilating sys-
EN- for a large mine varies, but the
ost of operation is not particularly
it will be met by savings
n compressed air, in increased eff
iency, and in the improved health of
nployes: the savings effected NAV
eturn the investment within a few
ears Miners consumption costs the
mining industry in South Africa about
6, 600 900 annually; it probably costs
he metal mines of the United States
1ore than that, in addition to many
YES and much misery. BY systematic