coal trade bulletin - Clpdigital.org

fulminate of mercury to blow a man's hand or
head to pieces.
Don't "lace" fuse through dynamite cartridges
This practice is frequently responsible for the
burning of the charge.
Don't explode a charge to chamber a hole and
then immediately reload the hole; the hole will
be hot and the second charge may explode prematurely.
Don't force a primer into a bore hole, and in
tamping the charge use pressure rather than impact.
Don't use a tamping bar as if it were a
javelin.
Don't do tamping with iron or steel bars or tools.
Use only a wooden tamping stick with no metal
parts.
Don't handle fuse carelessly in cold weather, for
when it is sold it is stiff and breaks easily.
Don't use fuse that has been stored or kept
near a boiler, steam pipe, or any other source ot
heat, or that has been exposed to moisture.
Don't use fuse that has been hammered or injured
by falling rocks or from any other source.
Such injury increases the burning rate, and there
have been cases where a fuse damaged in this
manner burned almost instaneously.
Don't cut the fuse short to save time. It is
dangerous economy.
Don't worry along with old broken leading wire
or connecting wire for electric firing. A new
supply will not cost much and will pay for itself
many times over.
Don't explode a charge before everyone is well
beyond the danger line and protected from flying
debris. Protect the supply of explosive also from
this source of accident.
Don't be in a hurry to find out why a charge
failed to explode. In case of a misfire, allow
AT LEAST 30 MINUTES
to elapse before approaching the hole.
Don't drill, bore or pick out a charge that has
failed to explode. Drill and charge another bore
hole at least 2 feet from the missed hole.
Instruct the men in the proper way of preparing
a primer, for many misfires result from the use of
improper primers. Teach them to cut off and
throw away an inch or two of the fuse before inserting
it in the detonator, for gunpowder (which
forms the core of the fuse) easily gathers moisture,
and the end of the fuse may have become
damp enough to quench the burning powder or prevent
the ignition of the detonator. Tnsist that
this cut be made squarely across the fuse with a
sharp cutting tool; if the cut is diagonal the
point may curl over the end of the fuse when it
is inserted in the detonator and thus prevent the
spit of the powder train from reaching the mercury
fulminate in the detonator, and if the tool
THE COAL TRADE BULLETIN. 33
is dull the powder grains in the end of the fuse
may be spilled during the cutting, thus weakening
the force of the split into the detonator and.
possibly preventing its ignition. Have the men
crimp the free end of the detonator around the
fuse tight enough to hold the detonator and the
fuse together, but not tight enough to cut off the
powder train in the fuse. Insist that they use
lor this purpose nothing but the proper crimping
tool. After crimping, the detonator should be
buried in the end of the stick of dynamite with
its axis parallel to that of the stick and its top
flush with the top of the dynamite. If the detonator
is buried deeper, or if the fuse is laced
through the cartridge, the explosive is liable to
become ignited from the side-spitting of the fuse
before 't is properly exploded by the detonator,
which not only reduces the efficiency of the explosive,
but creates a larger volume of gases, especially
of those gases most dangerous to the men
who must breathe them.
You should also see that detonators of sufficient
strength are used. Although No. 5 detonators
were considered strong enough for "straight" nitroglycerin
dynamite, the less sensitive gelatin
dynamite requires a much stronger detonator to
explode it properly. For this reason you should
never use anything weaker than No. 6 detonators
with gelatin dynamite; the universal experience is
that better results have been obtained with all
dynamites when strong detonators are used.
Warn the men as to any change in the normal
rate of burning of the fuse, so that they may cut a
FASTER-BURNING FUSE
long enough to give them time to seek a place of
safety. You should also see that the fuse is not
handled roughly, especially in cold weather, that
it is carefully protected from falling rock, and
that it is not abraded by the stick tamping the
hole.
Watch carefully for misfires. It is very difficult
to count the number of explosions during
blasting and to be sure that the charges have all
been detonated. For this reason the face, or as
much of it as is not covered by debris resulting
from the blast, should be carefully inspected as
soon as the roof has been made safe and should
be carefully watched during the removal of the
muck for evidence of missed holes. If such a
hole is discovered, under no circumstances should
you permit an attempt to pick out the material.
If no stemming!- has been used, as is often the
case in tunneling, you should insert a stick of
dynamite containing a detonator in the hole and
explode it at once; if stemming has been em-
fln tin- publications of tin* Bureau of Mines the material
packed en a charge in a bore hole is termed "ste-mming,"
and the act of packing the materia] is termed
"tamping." The bureau advocates the use of stemming
in bore holes with all explosives.