The diamond drill. (Crystal Falls, Iron County, Mich.) 1887-1996, 1913-02-15

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main Sub. these latterals being clorely
timbered with small timber WLen
the walls were reached the thin pillars
were attacked on tine inner end and as
they were removed the entire opening
covered with a heavy carpet OF tagging,
the timber shot out and the dirt above
allowed 70 cave down onto the tagging
The miners worked back 70 the main
sub taking the ore out comparatively
clean and letting the top down as they
worked back
In the mean time the fellows on the
second sub were taking ont the ore be.
low and working back similar to the
operations in the sub above. The work
has now progressed 80 that the backs
are taken out In the subs clear to the
timber above and as the carpet of lag
ging becomes thicker the problem OF
keeping the sand back is reduced.
This is not a cheap method but II is
safe and clean method The system
OF sampling has been arranged to ut in
with ths mining method and the oper-
ators are thus enabled to keep the grade
OF ore right up to the standard. The
mining and tramming is oil done by
the miners so that the labor charges
are higher but the proportion OF ore
taken ont to the development charges
il much greater and reduces the extra
cost made by the higher class Of labor
necessary and the extra timber
The big item, of course, is the TIM
ber. Timber Is the item that is going
to be greatest in most Of the west side
properties for many a day for the top
slicine system cant be worked success
fully without plenty OF timber.
The ore body at the Zimmerman Is
different from that at the Caspian IL
is compact, clean and comparatively
regular in its iron contents. All of
these conditions induced the operators
to attempt the mining Of the ore at
this property by the method employed
at the Tobin mine in Crystal Fails.
The Tobin system is specie Of the
caying system in which little timber
il used The system was first develop
cd at the Walpool mine of the Pewabic
company at Iron Mountain where the
entire chunk OF ore between levels was
undercut almost en- bloc and lot settle
down. crushing as ID settled The ore
body at that property was peculiarly
adapted to this method. The Tobin
people took this method and varied it
30 as to adapt to chunks or ore which
they undercut. first perforating the
chunk thoroughly with uprises. and.
after shooting away. X settled and
crushed into chutes that were at the
end OF raises runnp from the tramming
level 10 the sub. After the ore WAS
undercut Ii settled very nicely. crush
ing up to small dimensions and ran
ming through the chutes into the tr~m
cars. The method is very economical
one but cannot be worked in all kinds
OF deposits. The Zimmerman people
didn't get il started right and they
have had great deal of trouble as
resnlt the sand getting start on them
so that they have buried SONS of their
ore. They are getting squared away
for another start and we understand
are doing much better with il now.
This method requires experienced
hoads both TO get the ore moving and
to regulate its flow after IL has started
for too much Of pull at any one point
is apt 10 queer the whole procedure.
The plans for opening mp the Tnlly
were explained 10 Us by Supt Richards
recently. He proposes 70 vary the top
sliuing method in use in the Caspian
using series OF slopes and pillars so
as IL avoid the use Of 40 much set tim
Der
He proposes to drive subs every
twenty feet and from the subs run of
the rooms, driving the latter to the
walls. Between the rooms pillars will
be left thick enough TO support the
weight above. The backs OF the rooms
viii be arched aud when the ore is
taken out the floor will be covered
with carpet OF tagging Then the
pillars will be attacked from the next
sub ana worked from the far end back
20 the main sub The earth will be
allowed TO cave down upon the carpet
OF tagging.
Mr.. Richards is not az AL sure that
this method will work successfully but
no will start opening up that way ana
test it out IL he Is successful il will
reduce the timber charges very mater
tally.
His experiment will be watched with
a great deal Of interest by all operators
who have surface burdens to contend
with