The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1914-09-03

breast, underhand or back stopping. IN
which either open slopes or pillars are
left. In back stopping on square sets.
large falls may be caused by taking
too wide a span. Often men are In
ljured by smaller pieces of ore or rock
Mailing from the back or the sides. In
order to avoid these two dangers,
rooms, chambers or slopes should not
be carried larger than the nature OF
1.-THE ground will warrant and loose
rock and ore should be carefully trim
med from the back and sides. These
precautions apply also to breast stop
ing.
In underhand stopping, some. forms
LOT breast stopping, and other methods
in which open slopes are left behind.
the miner should remain under cover
Of the ore being worked. and should
keep working places trimmed Of loose
rock.
Mining in Large Ore sodiss.
In large ore bodies, where the ore Is
Of medium hardness or softness. vari-
GUS methods of mining are used, de-
pending on general conditions. In the
soft iron ores Of the Lake Superior
district some form OF top slicing or
subleyel slicing and caving Is en-
ployed. In each Of these methods
drift sets are used so that the dan
gers are much the same as when drift
ing in heavy ground. Here also 1t Is
important to trim loose rock from the
working faces and backs. Large falls
have been caused by trying to mine
soft ore bodies by the room Cor cham
Iber) and pillar method.
OF the other methods Of mining en-
Iployed in metal mines, including those
used in the various types of ore de-
posts found in the copper, gold and
other mines Of the western states the
most common are different forms Of
overhead (back) or underhand stop
ing, in which work Is carried on from
staging, waste rock, broken ore, or
square sets. Where the ore Is soft it
is usually necessary to work under
cover Of timbers; the dangers to be
guarded against are the same as in
drifting in heavy ground. Where the
ore Is hard 1t may not be necessary to
use much timber, but 1t Is often neces-
sary to provide stulls for holding the
weak walls in place. Slabs or chunks
on the hanging wall and loose pieces
Of ore should be pulled down.
Mining in Irregular Shoots, chimneys
and Pockets.
Another important class of ore de-
posits, as regards accidents from falls.
Is that made up of irregular shoots,
chimneys and pockets. In mining such
deposits the method best suited to the
conditions is selected. In general 1t
may be said that accidents from falls
may be avoided to great extent by
using enough timber. There is al
ways tendency. especially among
prospectors and others working on a
small scale, to excavate too large an
opening without the protection of
timber.
There still remains much to be
said as to the causes of accidents
from falls, but the Illustrations given
cover the most important ones. They
serve to point out that accidents from
falls are due chiefly to the following
causes:
l. Mining large areas underground
without the use Of timber.
! 2. Failure to trim or pick down
loose rock or ore from working places.
3. Improper timbering, including
the use Of too little timber. or the use
Of timber that is too small or not
strong enough; also improper spacing,
placing, blocking and tagging.
4. Delay in placing necessary tim
Der.
Any or all Of the above causes are
directly traceable to lack of knowl-
edge Of the nature Of the ground, lack
OF knowledge Of timbering, or care
lesnsess. knowledge of the nature
of the ground and proper timbering
methods are closely related, for If the
miner does not know how the ore or
rock breaks he can not select a suit
able mining method, he can not tim
Der properly, nor can he know when
or where to expect fall.
Some Hints to the Miner.
You may ask yourself the question: !
What can do to prevent accidents
from falls?" The answer is a simple |
one. Study the causes of accidents of
this nature, the more important of
which are set forth in this circular.
Study them in connection with con-
ditions in the mine where you are
working. Be sure that you know how
the ore and rock break, and then sat
isfy yourself as to the best method OF
supporting them. When you have
mastered these two things, make use
or your knowledge at all times. Fol-
low instructions given you by the un-
foreground boss. Above all, be care
'ui and patient in your work. If you
Ire an experienced miner, don't forget
me new or inexperienced hand; give
1im assistance or information when
'ver you can. If you will do these !
nings you can, besides protecting
Yourself prevent serious or fatal acct ls
tents to your fellow workmen.