The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1920-09-30

ming engineer Bureau of Mines).
Numerous accidents are still bein,
reported that have resulted from tn,
delayed explosions in drill holes Som,
of these accidents have been due t
retarded burning of the fuse, causine
the charge to explode after the min
ers had returned to the face, but the
majority have been caused by the mi
ners drilling or picking into uneX-
plOded explosives either in unexplod-
ed holes or in broken rock Although
the industry has been cautioned by
the bureau of mines, manufacturers
- of explosives and other agencies re-
garding the care that is necessary in
the handling of explosives, yet reports
of these accidents are still being re-
ceived and many of the accidents are
fatal They occur in spite of the best
efforts of the mine officials and men,
but many of those that have been re-
ported could have been avoided if the
following precautions had been OBJ
served:
Mistires should not be approached
even for the purpose of inspection I'M
til three hours have elapsed if fuse
was used. and ten minutes if electric
detonators or electric igniters were
used. These are minimum recommen-
dations. 1t would be preferable to
allow a longer time, for fuses have
been known to hang fire for II hours
First Determine Cause of Misfire.
The first inspection of the shot that
rafc oh 10 90
whether or not the cause be outside
of the drill hole. IL may be that the
fuse has not burned to the mouth of
the drill hole, or that the legs of the |
electric device electric detonatOr or /
electric igniter) or the elading wire is
short circuited or open circuited out
side the drill hole, or that the blasting
machine did not provide adequate /
current. If the cause lies outside of
the drill hole, it may be remedied
without disturbing the charge. Where
misfire has occurred in a hole con-
tanning an electric device, the blast
ing machine should first be promptly {
disconnected and removed.
When a hole has misfired an effort 5
should be made as soon as possible to
have it fired 1t is dangerous to have
about mine holes loaded with ex-
plosives. If it is not practical to fire
a plug in the hole or mark it in some S
way so that the miners will be mott E
fed of the danger of it,
If little or no tamping material was
used in the misfired hole an addi- r
tional stick of explosive may be plac- d
ed in it and fired, which is almost sure b
ID detOnate the entire charge. If Q
here is no room in the hole for the {
firing of the additional stick of explo-
near enough to the first so that a
,harge in the second hole will explode
n expose the first charge, and far
nough from the first charge so there
S no chance of the drill striking the
harge. Where practical, the holes r
hould be parallel. For short holes, a
tx feet or less. the separating dis q
ance should be at least Is inches and, a
possible, two feet or slightly more. IN
Jnder these conditions extreme care fe
hould be exercised in mucking to
make sure that the original charge ex- in
loded, or to locate any part of the OV
barge that did not explode 1t is re- to
that before firing the sec tn
nd charge the fuse used with the de- m
)nator or the legs of the electric de- 70
lnator in the first hole be anchored Il,
18th wire or strong cord outside the
rill hole. so that if unexploded. they ev
I,a ,araoxrad mara raodiIxr oo
Report and Chart Misfires. phi
In driving drifts or crosscuts the In
ork is usually continuously prosecut- sp
by either one or two shifts. The ful
en- are, therefore, going back to pa
Their their own face or to the face of
lie other shift. When the rounds of
)les are blasted the shots would be ha
united and a report made to the fore fin
an as to whether all shots were fir gol
l. The foreman or shift boss should spl
spect the face before the next shift thi
,es to work and inform the men re- tha
riding the misfires. Misfires should SUE
so be recorded on a bulletin board
tuated where the miners can readily rel
insult it before going to work. Many pre-
the missed holes in drifting are pol
tiers. When they fail to go off the !
nck should be thrown back and the viii
les re-shot. In drifting, therefore, it far
possible for the miners to be kept sch
quainted with the work of each 9TH
and accidents from missed holes
oided. In back holes quite fire.
emily one shot will shoot out other We
les also. and the danger is from I'M
ed explosives in the muck. This c
It should be carefully considered by wit
2 miners in drilling and firing holes vid
the back Ser
IN slopes a driller may be required ma
drill in one place one day and an whit
Ter place the next day. The miner Ant
Ould count the holes as they blast Z
d report to the shift boss whether Fis
~ are all exploded If there has mai
IN a mishre. the foreman should moi