The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1882-01-01
PROCESS OF DEDUCTION.


IRE in its tortuous journey from its
entrance at the top until it comes
forth in the bright, glittering bars of
silver as we see them at the express
office. Nothing comes to the mil
from the mine except what is
deemed "pay rock, and this, it must
be remembered, is pretty rich ore,
as the cost of mining and reduction
is no inconsiderable item. The
total expense in 1880, including the
outlay on construction account as
well as for mining and milling the
ore, was equal to $42 on every ton
of ore worked, hence it would not
do to handle cheap rock. The ore is
hauled on wagons to the upper floor
of the mill, having first been
weig had on platform scales just OUT
side the building. Here it is
dumped into capaci0us bin hold
ing 300 tons. 1t is the aim to keep
this bin full, SO as TO have a supply
on hand should an accident occur
in.the mine. The fine ore at once
falls through a screen to the floor
below, where it is followed by the
cOarser after it has been broken un-
der crusher, two of which are
here working 4 hours a day and
crushing twenty tons each. The
ore now drops through chuteS to
the fourth floor below, where it is
taken in ears and by hydraulic ele-
water carried back 10 the third floor,
and lhere dumped into hoppers
which automatically feed it into the
rotary dryers. These latter are cone
shaped lion cylinders, As inches in
diameter at the large end, 30 inches
at the small, and "a feet long.
They revolve at a speed of 6 revolu-
tionS minute, the ore being 20
minutes in passing from one end
to the other. Flames from wood
fire are constantly passing through
the cylinders, and the ore comes out
free from moisture. This is neces-
sary to prevent mating in the bat
terle5. There is an accumulation
of ore dust from the dryers, which
is caught in bins, and like the ore is
afterwards passed under the batter
les. The ore comes out of the
cylinders in steady streams, and
extremely hot, but not hot enough
to melt any part of it. Thence it is
wheeled to the batteries, ten feet
distant, and thrown into self-feeders.
A battery comprises five stamps of
$50 pounds each. A stamp is a 81
inch iron stem, fourteen feet long,
working PRECAUTIONARY, elevating
and falling 81 inches, at the rats
of ninety-fOur times a minute. On
the bottom of this stem is a boss of
$50 pounds weight to which a steel
shoe, weighing 105 pounds is at
tached, and between which latter
and a sceel die of ninety-six pounds
weight. the ore is crushed to i'm
dust. 1t may be imagined
what degree of racket forty such
stamps would make, with their in
cessant dropping, dropping, dropping,
day and night, never resting, ex-
cept TO replace worn shoe, or re-
pair some other injury. While near
them one must think like a deaf man.
To make himself heard is out of the
question. Each battery is connected
with d dust chamber, and a Stede-
feldt eXhauSter connecting with
the end of the chamber ears the
dust from the batteries, depositing
1t in bins. The pulverized ore being
screened as it comes from under the
stamps, is carried by a screw con-
veyOr TO the foot of an elevator
which takes it to a hopper covered
with a No. 20 wire screen. The
tine drops to the bottom of the hop
per, and that which has passed
through the batteries without suffi-
cient crushing, from the bursting of
a screeni or other cause is carried
back automatically, to be again put
under the stamps. The dust, or pulp
as it is now called is now started on
another journey, by screw con-
veyOr, and en- route Is mixed with
salt, which has also been dried in a
roasting furnace, reduced to -four
dust by means of a battery and
other appliances, and otherwise
treated as the ore has been. The
process is an ingenious Gr-
and was devised, we be-
lieve, by the chief engineer of the
mill, Mr.. Grant. The proportion of
salt required is regulated by means
OF cone pulleyS, and there is a table
at hand giving the percentage, the
average OF which is about seven
teen. Salt is necessary as chlori-
dizer, and about 800 tons a month
OF it are consumed.
The ore is now carried by the ele-
vator forty feet up to The TOD of the
roasting furnace. into
which it passes a bluiSh-grey color,
and out of which it comes, at the
bottom, a yelloWiSh brown. The
purpose of this roasting is to oxi-
die the base metals and chloridize
the silver, changing the sulphites
to ehlOrides, and aiding it to ANAL
gamate with quicksilver. The
Stedefeldt furDace-of which there
are two in the mill, each with a
for roasting from 40 to so
tons of ore in twenty-four hours
into which the ore is fed at the top.
was erected under the Immediate
supervisory of the inventor.
Mr.. A. G.. Stedefeldt, andiis sur
piled with all the latest improve
ments for condensing and saving
The silver that would otherwise es-
cape in the vapor or gases when