The Salt Lake tribune. [volume] (Salt Lake City, Utah) 1890-current, 1906-09-03
N|SSEN STAMP IN
THE BOSTON MILL
California Mining Journal Has
Exhaustive Article on the
Stamps Used.
CAPACITY OF PLANT
TO EXCEED ALL OTHERS
Main Advantage in Nissen
Stamp Lies in Avoid
ance of Slime.

The largest gravity stamp mill in tha
| world is to be built at GARFIELD, In Utah.
| by the Boston Consolidated Mining COM
pany, for the crushing and concentration
of ore from It's great low-grade copper
mines at Bingham, says tho Mining and
Scientific Press After severe tests, con-
Quoted for n period OF over six months.
by Mr.. A. J. BEETLES, the contract was
| awarded to Messrs. Fairbanks, Morse &
Co. for :he installation OF 36O Nissen
independent stamps. with q provision In
the contract that further number of $50
stamps shall be added after completion
of the first installation. By the tests 1t
was conclusively proved that on the ore
10 be treaued, which Is quartzite OF
medium hardness the Nisseu stamp has
capacity OF 1916 tons per twenty-four
hours through a twenty eight mesh
screen.
The daily capacity of the finished plant
may therefore be estimated at 1000 tons,
which will be much in excess OF the ca
pacity Of any existing stamp mill The
gravity tests were conducted with the
greatest fairness. Complete mills, In
Guiding besides the Nissen stamp, ordi-
nary iye-stamp batteries, rolls and circu-
lar mills OF various kinds. were run on
the same ore, SO that there could be no
error in comparing results under differ
ent conditions. Mr.. Bettles's problem was
TO reduce to twenty -eight-mesh ores
averaging LIS per cent copper and to get
the best possible product for concen-
tration at the least possible cost With
out wishing TO go into comparisons, 1t
may be said that the fact, as demon
sJrated during the test, that the Nissen
stamp made 10 per cent less slime than
any other competing mill, had much
weight in the final choice.
In the Nissen stamp there have been
retained the well-tried principles of the
gravity stamp. the new features being
particularly in the use of circular In
dependent mortar TO increase the dis
charge of the stamp. thereby increasing
It's capacity as much as 10 per cent In
proportion to the horsepower required
for It's operation. The oss-section of
our mortar is similar TO that OF the or
binary mortar, and the screen is relative
ly the same distance from the stamp in
It's horizontal points. Owing to the fact
shat the area Is so great and also that
the screen is In a position TO receive the
impact OF the pulp against IL at right
angles always q uniform crushing is
complshed without excess wear on the
screens. The mortar is effectually pro-
tecJed from wear by lining that is cast
in one piece and held In such a manner
that 1t causes no trouble by working
loose, The feeder is OF the improved
Challenge type. designed TO work easily,
80 that constant attention is not required
to keep the nuts and pins from becoming
loose; also by feeding the stamp inde-
pendently, steady and regular operation
is insured, so that the shoe and die wear
much moro evenly than in other types
of mortars, and allow closer feed. AS to
material used, the cam-shafts and stems
are Of hammered steel, the shoes and dies
are OF q special mixture or hard metal;
the cams and tappets are of cast steel.
a cam-shaft bearing is placed on each
side of every cam, which goes far TO
do away with the danger of breakage.
Briefly, the advantages of this type of
stamp lie in the ready and positive dis
charge-owing to the increased screen
surface, every part Of which is at right
angles to the splash in the avoidance
of slime. because, for the reasons above
cited, there is less regrnding, and econ
omy in power-chlefy for the same rea-
sons. The effect has been made TO re-
lieve the mill promptly and as thoroughly
as possible for pulp fine enough to pass
the screen, and although in the course OF
ten years experiment certain minor ad
vantages have been developed, the fea-
ture mentioned is the main Issue, and TO
II the success OF this type OF mill is due.
In operation, the Nissen stamp mill is
similar TO the ordinary hve-stamp bat
terry, save that each stamp is independ-
ent and larger. weighing 1900 pounds,
there is an independent mortar for each
stamp. and the screens are semi-circular
for each unit. From one TO six stamps
may be operated on the same cam shaft,
and any stamp In the battery may be
hung up for any purpose without inter-
fering with the continued operation of
the other stamps