Walker Lake bulletin. (Hawthorne, Nev.) 1883-1926, 1884-04-30
THE MOUNT CORY MILL.
A Full and Authentic Description of
the Process Used for the Reduction
of Mount Cory Ores.

Va HAouht Sory ores.
The process used at the MountCory
mill for reducing the ores of the
Mount Cory mine is somewhat differ
ent from that of mills to which Nevada
people are accustomed. The extraction
of silver is effected by means of hypo-
sulphite of soda in aqueous solution,
with following precipitation by means
of polisulphide of calcium. The pro
cess is not new by any means, but has
been practiced in various places in
Europe and old Mexico. 1t is called
Patera's Process, after MI. Patera, who
first applied it in Austria long time
ago. Its fundamental principle is that
hypo-sulphte of soda, certain aka
line salt tnot found in nature, however),
when in solution and coming in con-
tact with chloride of silver will dis
solve it, just as water dissolves sugar,
and that the silver may be precipi-
tated out of this solution again by
sulphureted hydrogen or sulphureted
metals which dissolve in water, leaving
the liquor--that is, the hyposulphite
solution-as it originally was. In
other words, the hyposulphite solu-
ton is regenerated, and may be thus
used again and again.
There are then used two kinds of
solution: one for dissolving the silver
out of the ore, the hyposulphte solu-
ton mentioned before, and one to pre-
cipitate the silver out of this first
solution, the poisulphide of calcium.
Its sulphur unites with the silver in
the former solution, and the silver is
thus precipitated as sulphide of silver.
When the sulpbide of silver has set
tied, it is run into centrifugal ma
chine making 500 revolutions per
minute. The water passes out of the
machine, leaving the sulphide of silver
tolcrably dry and lumpy. The rest of
the water and the superfous sulphur
are driven off by heating it in small
reverberatory furnace. After this dry
ing and desulphuration the material is
melted into bars in black.lead cruel
bles.
The Mount Cory ore contains chiefly
sulpburets which must first be changed
|
into chlorides, as has been shown,
before any lixivation may be success
fully applied. To this end, the ore
must be roasted with salt, and, in order
to roast ore, it must be crushed dry.
Dry crushing requires dry ore, and
since the Mount Cory ore contains
considerable moisture, it must be dried
| first, as also the salt. Since lixivIa-
ton, for certain good reasons, was
deemed the proper process to work
Mount Cory ore by, and since Il very
| important factor in teaching is to Sc
cure easy percolation Of the solution
through the ore, which is hindered, to
great extent, when the pulp is
crushed too fine, rolls were used rs
crushing machinery. Thus all parts
of the mill are the results of necessity.
These preliminary remarks show why
the mill is constructed as it is, and not
otherwise.
The ore is hauled by teams, which
dump the ore onto grizzlies, well
known to Nevada mining and mill
men. The fine parts drop through
the crate into the general ore bin.
The coarse pieces roll over the CRATE
TO a floor below, whence they pass
through 9x15 Blake crusher and into
the same general ore bin. Various
gates in front of the bin permit the
ore to fall into cars which take it to
the dryers. Other gates at the foot of
tho dryers discharge the dried ore
again into cars which take it TO an
iron hopper located over a Brodie
crusher. An automatic feeder at the
bottom of this hopper feeds the ore TO
the first set of steel rolls. They are
one eighth of an inch apart, After
having passed this first set of rolls, the
ore drops into the boot Of a chain
elevator which passes it into revolv-
ing screen. The latter divides the
pulp into three sizes: first, fine enough
for roasting (grains of one,thirtieth of
I'm inch in diameter); second, fnc
enough for the second set of rolls Zone
eighth of an inch), and third, not fine
enough for either, The third part
runs back to the first set of rolls for
renewed crushing, The first part runs
to conveyor screw, which carries the
pulp to the fine pulp elevator for lift
ing itinto the pulp bin overhead. The
second set of rolls rs similarly ar