The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1922-02-17
Representation
MINERS VIEW.
THE BIG COST OF MINING TIM.
Der MEANS THAT FORESTS
MUST BE RAISED.
(Skillings' Mining Review. J


way things have been going in re-
cent years, the tax item bids fair
to pass the labor cost, and in the
case of number of mines actually
has done so. Probably the next
highest item figuring in the cost is
fuel, and then comes, in the case
of underground mines, the item of
timber. Timber figures also to a
slight extent in open pit mines as
ties, etc, but in underground min
ing it is very large factor, and
an important one.
Minnesota Underground Mines.
There is normally produced in
| the state of Minnesota by under
|. ground mining methods approx
mately 13,800,000 tons of ore.
This includes the three Minnesota
| ranges, the Mesabi range contrib
| uting about 100000 tons, which
| figures 80 per cent of the total nor
NAL production of the range, the
balance being mined by open pit
methods. The Guyana range would
| normally mine 100000 tons by
underground methods, this being
so per cent of the ranges total
production. The Vermilion range
| normally produces 100000 tons,
ali of it being won by shafts and
| underground methods. Of course
the 1921 production was nowhere
near these figures, but the 1920
production was not far from it, and
| the figures used are very near the
average output for the past few
years.
This 13.SO0,0OO tons of ore per
year is all mined by the top slicing
and caving system or some modifi-
cation of it. This system requires
timber, tagging and boards, and the
total amount of timber and other
material used runs up into large
figures.
Mines Require Much Timber.
While the methods, and there
fore the timber consumption, vary
in different properties, according to
the nature of the ore body, the
| height of the slices, ETC., it is prob
| able that the consumption runs
| from one to one and a half lineal
feet of timber per ton of ore
mined. 1t is safe to use Ia lineal
the mines of the three ranges. On
L
cal feet of timber per year is re-
quired in all the mines of the state.
This timber runs all the way from
5 inches to "a inches in diameter,
but the largest part of it would be
from to 20 feet, with to IL
feet as the principal size. The total
| quantity of timber would figure
about a., 100000 BID. it,, and it can
readily be seen that a big annual
| cut is required to keep the mines
in operation. Old pioneers will re-
| call that in the early days of min
ing there were large stands of tim
Der covering the ore bodies -Shd
| ample mining timber could be OBJ
tanned close at hand This is far
from true now, however, and in
some districts the timber must come
from long distances. The mining
| timber of large diameter is particu-
larly difficult to obtain in certain
| districts.
The timber considered the most
desirable for use in mining is tama-
rack, this being found to be the
strongest and toughest. Jack pine
is used to a large extent, also Nor
way pine. some white pine, and
spruce Timber to be of any use
in mining must be tough, long
grained, and elastic.
An ash cap will shear as if
sawed in two, while the fibres of
tamarack or pine will resist the
pressure and hold the ground until
repairs can be made.
In addition to mining timber, the
mines of the three Minnesota ranges
require annually from $4,000 to
1000 cords of tagging and poles,
in lengths of 5, 6 and feet.
Tagging is easily obtained near the
mines in sufficient quantities.
The slicing system requires large
quantities of inch lumber for board
ing the sides and bottoms of the
slices and rooms; 40,000,00O to
100000 board feet of boards
are required annually for this pur-
pose, and the cost of this item near
ly equals the timber cost. So great
was the cost of the lumber, that
chicken netting has been substituted
in some cases to keep back the
waste material from the ore
Formerly cheap grade of pine
was used for mining boards, while
now re-sawed hardwood is found
to be cheaper in the long run and
give the best results.
Steel and Concrete.
Substitutes for timber have been
suggested and various methods have
been tried out to attempt to reduce
the consumption and cost of mining
timber. AS long as mining is car
ried on, however, timber will be
required and in large quantities.
Steel is used in certain cases now
where timber was formerly required,
and concrete has been found adapt
able for some purposes. Steel sets
and concrete lath have replaced tim
Der in shafts. and no large shaft
is now sunk with timber sets.
Concrete wall plates and end plates
have also been used in shafts with
success. Steel drift sets have been
used successfully in some Minnesota
mines, but their use is considered
limited. In a permanent drift
where there is no ground movement
to contend with, but where timbers
would be subjected to a rapid decay,
steel sets could be employed to
good advantage. Where only a
temporary support is required, or
where h avy ground movement
must be met, timber sets will prove
the most advantageous. 1t is en-
tirely probable however that more
use will be found for steel and
concrete as underground supports
as timber becomes scarce and more
expensive.
Lasting Qualities Vary.
Mine timber must resist not onlv
the weight and pressure of the
ground, but also the decay caused
by the dampness of the underground
air. Timber which is kept constant
ly wet will last longer, as will also
timber in q we'll uarf,1atoI H. "a