The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1921-08-25

that your management appreciates
the trouble, is able to handle and to
Eventually correct it, and has fore
man and crew who are both Jealous
and competent.
The most apparent difficulties in
the mine at the present time are two
areas where short sections of the
Slopes have caved in, crushing the
sets OF timber open when the caves
occurred and allowing several thOus-
and tons OF ore from the back to come
down on the COB.
Condition Not Serious.
III the vein at these points had any
considerable dip or inclination, these
caves would be a serious matter, for
in such cases the hanging wall caves
in with the vein; the ore gets mixed
with wall rock, and these is serious
loss. 1t is this falling in Of the hang
ing wall which constitutes the worst
feature of most caves and causes
them to be regarded so seriously in
mines generally. Fortunately, this
does not happen at all in the area
here under consideration. In these
Slopes, the dyke which forms a por-
ton of the vein, is bounded by smooth
walls, on each side of which is few
inches OF gouge and several feet OF
crushed ore and quartzite. The gouge
and the shiny, mica coated, faces of
the quartzite are as slippery as
grease, and when given an opportun-
ity to loosen up by having the slopes
under them idle or nearly idle for a
period of years, a mass of the ore
simply let's go and drops a few feet
to the top of the COB. 1t is actually
necessary to drill and blast the walls
as this fallen ore is removed, because
the caving does not extend to the
commercial width of the vein. There
is no ore lost and no dilution from
wall rock and the only reason the
caves are a source of loss to the COM
pany is that the extra labor and spe-
cial methods required TO remove the
fallen ore and prevent more from
falling, comes to a slightly higher cost
per ton for this ore than would OBJ
tain were it mined in the ordinary
way.
"The two Slopes in which such a
condition exists today, are the 1400
stope between raises and 9, and the
1000 stope between raises 20 and %.
Exceyt for a distance of about 80 feet,
in the latter instance, it is possible to
walk under, over and completely
around both of these areas of fallen
ground.
"As will be noted, the fal labove the
14OO is the more serious in point of
size The area involved is about 14O
feet long on the strike of the vein,
which is in this area about 20 feet
wide The back has however, been
completely caught up by timbering
from the muck pile and removal of
the fallen ore, closely followed with
COB, is already in progress. More
over the top of the cave is already
above the 10th floor, leaving only five
floors to remove under the 1900 level,
above which the vein is stopped and
filed The tonnage of fallen ore is
about 5000 tons and the tonnage in
volved in special methods of handling,
close filling, ct cetera,
about three times this figure.
1900 Cave About so Feet Long.
1.-THE 1900 fell recently and the back
had not been entirely caught up at
the time of this visit though it prob
ably will be by the time this report
has received your consideration. The
cave is about so feet long; the slopes
are about 80 feet wide at this point
A approximately $500 tons of ore have
fallen. The tonnage ultimately in
volved in methods of stopping requir-
ing extra labor can not be estimated,
for the top of the cave is at about the
eleventh floor only and it is not GER
tain that the condition will not recur
before the area is stopped out.
1T is possible to estimate roughly
what these falls of ground have cost
md will have cost the company from
he records of your engineer, Mr..
foreman. He complies from the daily
ihift boss reports, the charges for la
)or and powder of the various slopes
n the mine. In the spilled areas
here is actually a considerable saw
ng of labor for drilling and of cost of
powder, because gravity has done the
What more than offset by the extra
abor for timbering and filling involv-
d in removing the fallen ore.
Cost of Caves.
in the period from March, 1920, to
Nay, 1921, there were mined from the
topes, exclusive of those in which
hese falls occurred 22O,OS1 tons of
re at an average total cost for min
ng, shOveling, tramming. timbering
nd powder, of $1O4S per ton. In the
anne period, but including June 1921.
here were mined, 1860 tons from the
reas of fallen slopes at an average
otal cost of s11S6 showing that the
re involved in the spilled areas cost
he company 1913 cents per ton more
han the rest of the ore in the mine
The figure does not include compare
i've costs for the timber used, but
My for all labor and powder How