Santa Fe new Mexican. [volume] (Santa Fe, N.M.) 1898-1951, 1903-05-13

1T was known that the coarsest wa
, less than is inch mess, hence every
thing over that was sceeneds out a
. the shaft and not taken to the mil
for treatment. The gravel under 1-S o
an inch mesh was taken to the mil
and divided into five sizes according t,
coarseness. The. finest size would, 4
wet, make shines, as very little of i
was coarser than 100 mesh, and the
greater portion of it finer than 2Ot
mesh. This division of gravel into siz.
es was done by means of Mr.. Edison's
screening process.
Each of these sizes was next pass
ed through the air separator A sample
of the tailings amounting to about
per cent of the total material passing
was automatically taken. The entire
concentrate was panned with water
by hand and assayed by fire. The
tailings sample was similarly treated.
From the assay of this sample was
computed the loss of gold in the tail~
| ings.
"The finest gold was the most diff
cult to recover. Since these tests
Iwere made, method has been devised
and operated which greatly improves
the percentage of saving of this fine
gold.
1.-The apparent drop in the efficiency
of the next to the coarsest size was
due to the finding of one piece of gold
weighing about 10 milligrams in the
tailings sample. Disregardin that
piece the saving would have been 98.2
per cent, making a gradual advance in
efficiency, as the size of the material
increased.
"These figures show the results of
one of the many shafts tested, but do
not represent the best work done by
the process. The general average of
all the runs with all sizes of gravel
from the finest dust to is inch mesh
and carrying from cents to 35 cents
in gold per cubic yard, showed 925 per
cent of the gold saved.
Upon a large scale the process op-
crates as follows: A steam shovel ex
cavates the gravel and deposits it on
grizzlies having a spacing that will al
low the passage of the coarsest gold
which the deposit is known to produce.
The stones thus removed are left on
the spot. The finest fall into cars, are
hauled in trains to the mill, and dump
ed into storage bin from the bottom
of which it is fed to an inclined con-
veyor leading to the top of the sizing
house. In passing by gravity through
the screens the gravel is divided into
the number of sizes required by the
character of the material from four to
eight. Each size of the gravel coming
from the screens is conveyed to a |
group of separators, properly adjusted |
to treat their particular size of mater
ial. Passing under all the separators
are two conveyors, one carrying the
to the stock house for final
refining and the other carrying the |
to the dump or to the empty |
cars which dump the tailngs on their |
way back to the steam shovel.
"The data for shaft No. 9 are as fol-
lows: Total gravel excavated 33.S cubic
yards; weight 137,464 pounds; total
gravel treated in the mill 1886 pounds.
This was divided among the five sizes
as follows: A the finest, S,911 pounds;
B, 1922 pounds; c, s,04O pounds; D,
S,075 pounds; E. the coarsest, 6,S4S
pounds. The results were as follows:
A, weight of gold in concentrates, 5132 |
weight in tailings 14740
milligrams, per cent of gold saved III;
B. weight of gold in concentrates,
/, 1915 milligrams, in tailings 6665 mil
Iigrams, per cent saved $685.; G, concen-
trate Bats milligrams, tailings 1910 mil
ligrams. per cent saved 97.S;j D, in con-
centrates 1867 milligrams; tailings 34O.-
As, per cent saved 915; in concen~
trates 25425; in tailings 26.41; per cent
90; total weight of gold in concentrates
II, 1882 milligrams; in tailings 65662
per cent saved 95.
"The concentrates are further treat
ed, in order to reduce their bulk ana
Increase their value, by passing them
over an Edison magnetic separator
which removes the magnetic black
sand or iron ore. This magnetic Is
found almost without exception In all
placer deposits and being the heaviest
of the gravel, with the ex-
ception of the gold, 1t usually forms
the bulk Of the concentrate. This iron
Is also in demand as fiux In copper
and for other purposes. 1t
may, therefore, be valuable by-pro-
duct Of the plant, and by the use OF
these magnetic separators it is concen-
trated cheaply and efficiently, and may
be disposed of profitably."
1uCUMCARI FlGHT.