The evening herald. [volume] (Shenandoah, Pa.) 1891-1966, 1899-10-18
EXPLOSIVES
IN MINES.
Suggestions as to How They Should be
Used With Safety.
IMPORTANT TO ALL COAL MINERS
They Should Understand the Nature Of
Different Kinds of Explosives and
the Adaptation Of Each to
Different Kinds of
Work.

DlHefenJ KINDS OF
Work.
'The Use Of Explosives in Mining" is a
subject ably treated in the October issue of
Mines and Minerals, published at Scranton.
The article says:
The thorough knowledge of explosv yes
and their use in different kinds of mining
work is Of the utmost importance to all con
nocted with mining. They should under
stand the nature Of the different kinds of ex-
posives used, and the adoption of each kind
to different kinds Of work to be performed
Some explosives are quick and strong in their
action while others are slower and develop
their energy gradually The one class is
adapted for use Ia blasting rock aud very
hard coal, while the class last mentioned is
adapted to soft Goals and to pillar work. OF
common blasting powder many have not
learned to distinguish between the action of
small grained powders and those of larger
grain. These belong to the class known as
dehagmtiug explosives. All the powders of
/ this class burn slowly. The ignition starts
upon the outside of each kernel aud burns
inward to the heart One kernel ignites the
other and the ignition travels in this way
from kernel to kernel 1t is easy to see that
if a number of large sized grains of this
powder are placed in drill hole and are ig-
nited by fuse, the explosion will not take
place instautaneousy. The burning of the
first kernel will generate a certain amount of
gas, aud the amount of gas increases AS the
! ignition goes ON, until the pressure of the
gases set free by the ignition is sufficient to
tear the coal apart or to burst the confning
walls. When the pressure has reached this
point, the explosion takes place Now, it is
evident that if too much powder has been put
into the drill hole the explosion will take
place before the powder is all burned, and as
"a consequence, some Of it will be thrown out
burning into the air Of the mine workings.
This causes large amount of flame and the
energy Of the burning powder is largely ex.
| pended upon the air instead of being con-
sumed in mechanical work upon the coal
| This result is what is termed a blowout
| shot.
The use of too fine grained a powder in
soft coal results in blowing the coal to pieces.
This often entails loss to the miner. and
there IS also danger resulting from the fine
dust produced becoming gnited in the flame
OF the blast and caused by windy shot
| The stemming or tamping is another
matter of importance. 1t is always necessary
that the stemming should be strong enough
to offer a resistance to the charge equal to
that OF the walls. Where the stemming is
too short, it will yield before the develop
ment Of the explosive force is sufficient to
rend the walls. This causes a 'blown-out'
shot. Or, if the diameter of a drill hole is
too large, the pressure upon the stemming
Will blow it out from the hole before rending
the walls. The diameter OF drill hole is
| then imnnrtauf g..
soft coal may be made in two and one-half
inches to sometimes three inches in diameter,
but the larger grained powders are then used
In such holes, the holes being longer and the
charge placed deeper than in hard Goals
Finer grained powders are usually used in
coal in smaller charges, and in holes of
smaller diameter, 1t is better in this case to
use small charges and a number of them dis
tributed through the seam, than to depend
upon heavier single charge; as the small
charges distributed at different points will
exercise more uniform pressure and break
the coal better.
Much difficulty is often experienced by
miners especially in going into new field
where they are not familiar with the char
acter of the coal All Goals do not shoot
equally well. In some Goals the shot will
often seam out This causes much trouble
until it has been learned to drill the hole to
the dip or rise so that the pressure will be
exerted across the weak strata, rather than in
line with the strata. In every new field ex-
perience must teach the proper placing of
| shots. We find often the complaint being
made by some that the coal does not shoot
WE'LL when another miner, in an adjoining
room, will find no difficulty whatever. The
source of this trouble is usually in the miner
| himself. Too often the coal is simply
| butchered. A good miner is not a good
| butcher. He understands the importance of
cutting and mining his shot. No argument
is required to teach him that the trouble with
/ his neighbOr lies in placing his shots too far
on the solid, or in living them fast at the
| top or the bottom, or in not properly grip
ping a breast shot. We must not expect
powder to do its work unless we give it op-
pOrtunity to act No good entry-driver will
place a six-foot shot alongside of a three
foot cutting or twO-foot mining. We have
known some miners to place such shots and
then, fearing the result for themselves, they
would use a long fuse and hurry away down
| the entry TO be out of harms way when the
explosion took place. Such practice can
only be looked upon as reprehensible. For
this reason, many mine bosses prefer the use
of squibs to that of fuse, inasmuch as the
miner has not the same opportunity to place
questionable shot and then hurry away.
THE practice of stemming a hole with
coal dust or fine coal taken from the floor of
the room is very bad, and we are glad to say
not INDUCED in longer by any intelligent
miner. The fine dust becomes ignited by the
flame of the blast and is at once converted
into carbonic oxide gas, which extends the
flame of the shot which reaches often far out
upon the entry. A shot of this character
may be the sole cause of mine explosion.
and the rush of fame and gas from the room
may stir up sufficient dust from the floor of
the passageway 10 transmit the flame great
distance along the entry.
Much is being said lately with reference
to the use Of liquefed air as an explosive
agent. AT some time in the near future this
result may be attained, but at present its
expense acts as a bar to its use. The pressure
developed may reach as high as fifty tons to
the square inch. The use of such an ex-
plosive would obvate the risk of explosions
incident to blasting"
Bargains.