Improved Method of and Means for the Preliminary Treatment of Gold and Silver Ores.
Year: 1897

page_text: Date o Application, 14th June, 1897
Complete Specification Left. 14th Mar. 1898-Accented 11th June 1808
PROVISIONAL SPECIFICATION.
Improved Method of and Means for the Preliminary Treatment of
Gold and Silver Ores.
I, CHARLES WETHERWAX, of Best, Rensselaer County, in the State of New York,
United States of America, Manufacturer, do hereby declare the nature of this
invention to be as follows:-
My invention relates to the preliminary treatment of gold and silver ores with a
view to prepare them for the recovery of the precious metals therefrom and it
comprises an improved method of, and means for, facilitating the separation and
ultimate elimination of the iron, copper, arsenic, antimony, and other metallic
compounds associated with the precious metal in the ore.
The invention consists essentially in subjecting the crushed ore to the action of
a suitable solvent or leaching solution under high steam pressure. This leaching
operation is performed in a digester in the form of an upright or horizontal
cylinder provided with an inclined perforated false bottom and with a manhole at
top for charging and another just above the lower part of the perforated false
bottom for discharging. To the space beneath the false bottom on which the
charge of ore is received and to any other convenient part of the digester are con-
nected pipes for the introduction of the steam for heating the contents of the
digester, for facilitating the solvent action of the leaching solution, by the passage
of the steam through the mass, and for maintaining the required pressure in the
digester, a steam nozzle being also provided above the false bottom so directed
as to facilitate the discharge of the ore after treatment. A circulation pump would
be connected with the top and bottom of the digester by means of a system of
pipes so arranged and combined with two-way valves that either an upward or a
downward circulation of the leaching solution and washing water can be effected
through the contents of the digester, the pump running only one way. The solu-
tion when introduced at the upper part of the digester may be projected upwards
against the crown of the digester or be otherwise distributed uniformly over the
mass of the ore to be treated. The upper part of the digester is connected with
a condenser for the steam and obnoxious gases carried off along with it, suitable
cocks and other necessary appurtenances being provided for controlling the work-
ing of the apparatus, for drawing off the solution, and clearing out the space below
the false bottom. The perforated false bottom may be dispensed with for very
finely crushed ore.

page_text: Improved Method of and Means for the Preliminary Treatment of
Gold and Silver Ores.
I, CHARLES WETHERWAX, of Best, Rensselaer County, in the State of New York,
United States of America, Manufacturer, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
My invention relates to the preliminary treatment of gold and silver ores with
a view to prepare them for the recovery of the precious metals therefrom, and it
comprises an improved method of, and means for, facilitating the separation and
ultimate elimination of the iron, copper, arsenic, antimony, and other metallic
compounds associated with the precious metal in the ore.
The invention consists essentially in digesting the crushed ore in a solution of
a suitable solvent or reagent under high steam pressure, the operation being per-
formed in an apparatus such as that illustrated in the accompanying drawing,
wherein A is the digester provided with an inclined grid or apertured false
bottom B and connected with a centrifugal pump C by a system of circulation
pipes; the pipes being preferably connected with the digester below the grid B,
and at a point above the level of the charge of ore but below the level of the super-
natant solution, the pipes connected with the suction and delivery of the pump
being so controlled by stop cocks that a circulation of the leaching solution may be
maintained either in the upward or the downward direction through the mass of
ore contained in the digester. To the bottom of the digester is connected a pipe D
by which live steam at a pressure of, say, eighty pounds (more or less) may be
introduced below the false bottom B so as by passing up through the charge of ore
to cause a circulation of the leaching solution and bring it into intimate contact
with the ore. E is a condenser with which the upper part of the digester is con-
nected. The digester and its contents may be heated by an internal steam coil or
by an external steam jacket (which are not shewn but will be readily understood)
to prevent excessive weakening of the solution by the condensation of the steam
injected therein.
The digester is provided at top with a manhole F for charging in the ore and
with a valve G closing an outlet pipe connected to the digester just above the lower
part of the inclined grid B for discharging the contents of the digester into a
sluice H provided with ripples and other usual means of intercepting the gold. Jis
a nozzle whence a jet of steam may be directed towards the discharge aperture to
facilitate the discharge of the solid matters, and I is a manhole in the bottom of
the digester for cleaning out the chamber below the grid B.
The solution with which the ore is to be treated may be contained in a tank K
whence a pipe leads into the upper part of the digester and terminates in an up-
wardly directed nozzle L. M is a water tank also connected with the same nozzle,
the connection in each case being controlled by stop cocks.
The nozzle is upwardly directed in order that the jet of liquid may be pro-
jected against the top of the digester so as to be evenly distributed over the
contents.
The operation is performed as follows:-The necessary quantity of solution to
cover the charge of ore is first admitted into the digester from the tank K and
then the charge of ore is introduced and the digester closed. If the digester is
provided with a steam coil or jacket the contents are heated and then steam is
admitted by pipe D and the contents submitted to digestion for an hour, or any
greater or lesser period that may be necessary The solution may be meanwhile

page_text: circulated by the pump, although such forced circulation is not indispensable when
steam is injected below the grid B. The circulation would generally be in the
upward direction when finely crushed ore is treated, and in the downward direc-
tion only when the ore is in coarse lumps. When the operation is complete, con-
nection is opened with the condenser E in order to discharge and condense the
obnoxious gases evolved, and then the valve G is opened and the contents of the
digester discharged on to the sluice H, the discharge being assisted by the steam
jet at J and by water from the tank M to wash out the digester and carry the solid
matters over the sluice. Instead of steam being injected it might be generated in
the digester which would in that case be externally fired and might be placed in
a horizontal instead of a vertical position.
The solvent or reagent employed in the solution may depend upon the nature
and condition of the ore to be treated and may be of any kind known to be suit-
able for the purpose and the duration of the operation may vary according to the
nature of the ore, and of the solvent or reagent employed, and will generally be
less the higher the steam pressure under which it is performed.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. The herein described method of, and means for, treating gold and silver ores
for the recovery of the precious metals therefrom, which consists in digesting the
ore under steam pressure in a solution of a suitable solvent or reagent, as specified.
2. The herein described method of, and means for, treating gold and silver ores
for the recovery of the precious metals therefrom, which consists in digesting the
ore in a closed vessel and under high steam pressure in a solution of a suitable
solvent or reagent which is caused to circulate through the ore under treatment
substantially as specified.
Dated this 14th Jan
1 1000