The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1920-09-09

selection of explosives. etc. However,
numerous air samples at blasting faces
in metal mines almost invariably re-
veal presence Of dangerous gases, due
generally to incomplete combustion,
these dangerous gases being usually
co and oxide of nitrogen. Dangerous
percentages upwards of per cent?
OF co have been obtained at drift
faces in metal mines after blasting
with explosives of ammonium nitrate
as we'll as gelatin base, detonated with
No, as we'll as with No caps, fired
electrically as we'll as by fuse, tamped
and untamped
THE most dangerous gas found in
fumes of explosives is co. of which
quantities mp to and over 1 per cent
are frequently found in the general
air around newly blasted faces in
metal mines and frequently as much
as two or three tenths of 1 per cent
in air from muck piles. several hours
after blasting This gas gives head
ache in air with proportions as low as
COS per cent and is dangerous at OF !
per cent. and quickly fatal when over
O5O per cent. Another gas sometimes |
found is nitrous oxide. and its effect /
while serious, is not likely to be so |
quickly fatal as that of CO. however |
when dynamite burns instead of ex-
ploding the nitrous oxide content of |
surrounding air may be sufficiently /
high to cause death to those breathing !
it Other dangerous gases. such as
H2S Hydrogen sulphide). SOP (sul- /
phur dioXide). etc. may also be found I
in explosive fumes but rarely present /
in harmful proportions However.
straight nitroglycerine explosive dyna-
mite gives off several times as much
CO gas as gelatin or ammonium base
explosive. hence straight nitroglycer-
ing should never be used in the con-
fined places found in mining.
Ventilation Only Preventive.
1T appears that, at least at present,
there is no explosive applicable to
metal mining in which there is any
guarantee that formation of dangerous
gases can be prevented in blasting,
hence the one feasible preventive is
ventilation.
Toll in Coal Mines Small.
1T is significant that in 1919 the
great coal mining industry of the
United States which is compelled to
give minute attention to ventilation,
had but three deaths from 'suffocation
from explosive fumes, though more
than seven hundred sixty thousand
men were employed, or about there
lines as many employees as in our
metal mines Metal mines only too ;
frequently place entire reliance on
natural ventilation or on compressed =
iir. and both are likely to be ineff-
,ient, dangerous, and in the long run
costly. A compressed air blower viii }
'arely deliver to a working face more
han 100 to $50 cubic feet of air per
900 cubic feet, and there is danger
hat at least occasionally, the COM ;
pressed air may, through defective
system. be charged with Z
dangerous gases; ordinary ventilation
Methods by mechanical fans produce
iir circulation at cost of about to
,ents per 1000 cubic feet, and with
roper supervision will readily deliver
several thousand cubic feet of air per
minute to working faces, instead of
he 100 or thereabOuts cubic feet per
minute by compressed air blowers.
Methods of Ventilatng.
For dead-end faces of drifts cross
outs, raises winces and shafts, small !
electrically driven FANS direct con-
lected to One-half to 10 horsepower j
force air through canvas tub