An Improved Process of Treating Gold Ores.
Year: 1897

page_text: An Improved Process of Treating Gold 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 ores, more particularly
refractory gold ores with a view to liberating the gold from its combination or
association with other elements or compounds in the ore which resist the action
of the usual reagents, and so preparing the gold for recovery by usual means.
The invention consists essentially in digesting the pulverized ore under steam
pressure in a solution of caustic soda or potash and water glass, the average pro-
portions and strength being, say, eight ounces of sodium or potassium hydroxide
and eight ounces of sodium or potassium silicate in solution, to the gallon of water
but these proportions are susceptible of variation according to the nature and con-
dition of the ore, and in treating ore in a wet state allowance should be made for
the contained moisture. The solution should be put into the digester first and then
sufficient pulverized ore added to be covered by the solution, the whole being then
submitted to digestion under a steam pressure of eighty pounds, more or less, for
an hour, more or less, the period varying inversely as the steam pressure employed.
The digester may be heated by an internal steam coil or otherwise.
Dated this lot daw of Tuly, 1907
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.
An improved Process of Treating Gold 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 ores, more particularly
refractory gold ores, with a view to more completely liberating the gold from its
combination or association with other elements or compounds which render the
ore difficult of treatment by the usual reagents, and so preparing the ore for
recovery of the gold therefrom by usual means.
The invention consists essentially in digesting the ore under steam pressure in
a solution of water-glass and caustic soda or caustic potash. The average pro-

page_text: portions of the reagents and the strength of the solution which may be emp...
are, say, 8 ounces of sodium or potassium silicate in solution and 8 ounces o₁
sodium or potassium hydroxide to the gallon of water. These proportions are,
however, susceptible of variation according to the nature and condition of the ore,
allowance being made in the strength of the solution when treating ore in a wet
state for the dilution of the solution by the contained moisture. The quantity of
solution used should be sufficient to cover the ore, the whole being submitted to
digestion under a steam pressure of 80 pounds (more or less) to the square inch
for an hour (more or less) the duration of the operation necessarily depending on
the nature and condition of the auriferous mineral treated and on the amount of
the steam pressure employed the period generally varying inversely as the amount
of the pressure.
The operation may be performed 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 supernatant 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, 80 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 con-
denser with which the upper part of the digester is connected.
The digester and its contents may be heated by an internal steam coil or by an
external steam jacket (which are not shown 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 just above the lower part of the inclined grip B for discharging the
contents of the digester into a sluice H, provided with ripples and other usual
means of intercepting the gold. J is a nozzle whence a jet of steam may be
directed towards the aperture G 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 of water-glass and caustic alkali may be contained in a tank K
whence a pipe leads into the upper part of the digester and terminates in a
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 L is upwardly directed
in order that the jet may be directed 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 (more or
less). The solution may be meanwhile 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 direction only when the ore is in coarse lumps.
When the operation is complete connection is opened with the condenser E in
order to discharge and condense the fumes or obnoxious gases evolved, and then
the valve G is opened and the contents discharged onto 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.

page_text: Instead of steam being injected it may be generated in the digester which would
in that case be externally fired and may be placed in a vertical or horizontal
position.
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 process of treating gold ores, which consists in digesting the ore under
steam pressure in a solution containing water-glass (sodium or potassium silicate)
and caustic soda or caustic potash substantially as specified.
2. The herein described process of treating gold ores, which consists in subject-
ing the ore in a closed vessel, to the conjoint action of steam heat and pressure
and of a solution containing sodium or potassium silicate and caustic soda or
caustic potash caused to circulate through the ore substantially as specified.
Dated this 30th day of April 1898.
A. M. & WM. CLARK.
Chartered Patent Agents, 53, Chancery Lane, London.
A. M. & WM. CLARK.
Chartered Patent Agents, 53, Chancery Lane, London.