The Salt Lake tribune. [volume] (Salt Lake City, Utah) 1890-current, 1906-07-16
SLASH SYSTEM OF
EXTRACTION DESCRIBED
Eastern Journal Gives Method
of Prominent Utah Min
ing Company.

The slash system of mining Is a
modification of both the square-set
system and the caying system, which
Is being employed at the Jordan and
the Telegraph mines Of the United
States Mining company at Bingham,
Utah, says the Engineering and Mining
Journal 1t has been In use there for
several years and has proved quite sat-
isfactory. Like other methods II has
Its advantages and disadvantages, but
It's cardinal point is that It Is a very
safe method Of mining In heavy slopes.
1t Is an underhand, square-set method.
In which the overburden Is allowed to
follow down after the caved tmbers'
Tho ground at the United States
mines Is heavy and the slopes are
large. The wall rock is limestone, in
which q soft sulphide ore has been
deposited by replacement, A raise Is
put up to the top OF the stope. Then
the top slash is mined out by means
of square sets, the posts being plant
ed on the ground with bracers, or
spreaders, between them at the bot
tom. The set is Jagged, and floor
Is also laid. When the sets have been
pushed to the boundaries and the ore
on that floor or slash has been mined
out, holes are bored into the posts and
loaded with dynamite.
They are then blasted and the over
burden caYed down upon the floor.
In case the ground becomes too heavy
the floors can be mined In sections and
each section cayed as soon as the ore
in that section is mined out. The
miners then drop down set in the
raise and begin to mine out another
floor, or slash, The floor OF the slash
above IS caught up by the square sets
and so the waste Is kept from mixing
with the ore. This slash or floor of
ore is mined out rs before. a floor Of
i,,rl 10 l. l.r l,nI,, bot q =
the mining progresses. This slash Is
cayed and the process repeated In the
slash below,
Advantage of Method.
The timbers used in these mines are
SXS-inch Oregon pine. The posts are
feet, feet 4 inches or feet
inches long. The caps are 8 feet
inches long, as are also the girts, so
that the caps and girts are placed at
5-foot centers. No timber is recovered
and no back Of ore Is caved. The ad-
Vantages OF this method are that all
the ore is recovered, that smaller tim
bers can be used and that the method
Is safe for the miners, The dsadYan-
tages are that 4 bottom OF ore must
be taken out on each floor. IL IS like
continually mining on q sill floor, ex-
cept that sill tlmbers are not laid.
AS q result the cost of breaking the
JIG ID IllSI. INuISto Dc NllNSH III
the solid rock instead Of carried up
In the sets as In the case of ordinary
square-set mining. Moreover, the
slopes are very hot and the air poor,
because there are no raises to levels
above to promote ventilation, The de-
cay of the timbers, which follow down
with the caved overburden soon fouls
what little air gets up into the stope'
The crushing of the caved overburden
and the timbers also aids in making
the air hot.
This system could be easily convert
ed into a regular caving system by
oaving a back Of ore each slice, but
on account OF the value of the ore and
the consequent loss of some Of It, en-
tailed by the caving system, this is not
attempted at the United States mines.
AS with any system 1t is simply that
method which Is cheapest considering
everything coming into tho problem.