The diamond drill. (Crystal Falls, Iron County, Mich.) 1887-1996, 1914-02-21

! at the Hamilton shaft OF the Oliver
Iron Mining company. the work OF
refining with reinforced concrete
diyiders end plates and concrete ponr-
ed walls. has been finished to depth
of one thousand feet--twelfth level
where pumping station is now being
cut ont. This station is about thirty
feet wide and one hundred feet long
and will contain one set of the electri-
cal centrifugal pumps. Another pump
ing plant will be located on the six
teenth level. about 430 feet below the
twelfth level The shaft Is to be re-
lined for the entire distance. the de-
cision being TO make the Hamilton
permanent outlet for the Chaplin mine.
The original Hamilton shaft was
sunk in 1891 by the Hamilton ore
company under the direction of John
t Jones, who was then superintend-
ent of the property. IL contained six
compartments. The size was seven
feet by twenty -one feet four inches.
To provide for column pipes and trans
mission cables for the new electrical
pumps, it was found necessary to in
crease the inside dimensions to nine
feet by twenty.one feet four inches,
thus making the poured walls six
inches thick. but this did not increase
the outside measurements of the form
or wooden shaft. The shaft now con-
sists of eight compartments two for
skips or bailers and two for cages. each
four feet eight inches by six feet four
inches, three compartments for pipes
and transmission cables and one for
ladder, each two feet four inches by
four feet eight inches, with concrete
slab partitions between cage and skip
compartments. pipe and skip compart-
ments and ladder and skip comtpart
ments.
In order TO facilitate the work. a
concrete mixing plant was built near
the shaft The plant consists of a
crusher, bucket elevator, revoloying
screen, two concrete mixers, pocket
divided into three divisions for sand,
gravel and oversize, and drying
room equipped with an overhead hand
travelling crane.
The work of reclining the shaft is
done in sections Each section is
started on permanent bearers located to
support the old timber sets and work
ing upwards The average amount OF
material for reclining one six-foot
vertical section Of the shaft is one
cord OF stone for back filling, ten
cubic yards of concrete and $50
pound of steel for reinforcing.
The work is carried on in three
eight-hour shifts and the average time
required TO concrete six vertical feet is
twenty -four hours, pouring concrete
and removing an equal amount OF
forms When the forms are removed
they are taken TO the surface. thor.
oughly cleaned and given a coat OF
crude oil before being used again
The work was started on May Bird.
1912, distance about eightytprse be-
| low collar of the shaft and was com
pleted to the surface on June Goth
The average rate Of progress since the
work, not deducting delays, has been
between sixty and seventy feet per
month. The preliminary estimate had
been one hundred feet, but progress
as retarded owing to the condition of
the timbers In the old shaft and diff.
Guilty in removing them avoid acct
denst, and unexpected in flow of water
causing suspension Of work for
nearly month.
A force of about forty men are EN-
ployed in the work in various capaci-
ties and the shaft will not be complet-
ed to the bottom level for several
months.
$ w Tarr. Of Duluth, chief con-
struction engineer for the Oliver Iron
Mining company. has had general
supervision of the work. Much of the
information above was secured from a
paper prepared by him and read at a
meeting of the Lake Superior Mining
Institute. -Press