Method and Apparatus for Extracting Gold and Silver from their Ores by the Combined Action of Amalgamation and Centrifugal Force.
Year: 1893

page_text: Date of Application, 30th Dec., 1893-Accepted, 17th Mar., 1894
COMPLETE SPECIFICATION.
Method and Apparatus for Extracting Gold and Silver from their
Ores by the Combined Action of Amalgamation and Centrifugal
Force.
I, ALBAN TRUG of Verespatak via Abrudbanya Hungary in the Empire of
Austria Engineer, 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:-
This invention relates to a method of and apparatus for the extraction of gold
and silver from their ores by amalgamation in combination with centrifugal action
and it consists mainly in subjecting the ore sludge to the action of a rotating
vertical conical vessel open at the upper end into which the mercury and the sludge
composed of ground ore and water are introduced, whereby the mercury is caused
by the centrifugal action of the vessel to be applied in a thin layer over the inner
surface of the vessel, over which layer a thin layer of the crushed ore is also caused
to flow by the centrifugal action, in an upward direction. By this means the
particles of gold or gold bearing particles of the ore receive a sufficient centrifugal
force to cause them to impinge upon the layer of mercury, so as to have their gold
taken up by the latter.
The accompanying drawing shews a vertical section of a centrifugal amalgamating
apparatus constructed according to this invention.
It consists of a conical vessel Kopen at top and fixed to a vertical shaft A
rotated by a pulley S, the inner surface of which vessel has annular ribs r formed
on it, of which the top one projects to a greater extent than the others.
These ribs have the object of preventing the mercury from falling down in case
it should have any such tendency owing to variations in the speed of the vessel.
In addition, the ribs prevent those particles of gold from rising up and escaping
at the top of the vessel that, after passing through the layer of mercury, are
deposited on the surface of the vessel without having had time to become dissolved
or amalgamated by the mercury.
The inclination of the conical vessel must be such as to insure that with the
normal speed of rotation, the mercury introduced shall be uniformly distributed
over the whole surface of the vessel extending from the rounded bottom w to the
uppermost rib, and to remain in this condition during the rotation. Within the
vessel K is a distributing disc E fixed to the shaft A and provided with radial
ribs a and a circular rim, which dise serves to receive and impart centrifugal
motion by means of the ribs to the continuous supply of ore sludge entering
through the pipes R, as also to a supply of electrolyte (such as dilute nitric acid or
Glauber salts) for reducing the electrical resistance, entering through small
tubes R. At the same time the curved rim b₁ has the effect of imparting an
initial upward velocity to the ground ore thrown by the disc against the layer
of mercury on the conical vessel, such velocity being sufficient to carry up even
the largest particles suspended in the liquid, and thereby to prevent the surface
of the mercury from becoming coated with such particles.
The liquid carrying the ground ore being thus uniformly distributed over the
surface of the mercury, it receives rapid rotary motion, causing the heavier gold
bearing particles to be separated by centrifugal action from the non-gold bearing
gangue, and to be brought into intimate contact with the mercury so as to effect
the amalgamation of the gold therewith, while the specifically lighter gangue is
arried up by the upward motion of the liquid, and discharged over the upper edge

page_text: of the vessel. The introduction of the sludge into the centrifugal apparatus is
effected in such manner that it is first led into an annular trough Fabove the
vessel K from which it flows down through the pipes R' on to the distributing
disc E.
The sludge freed from gold which is thrown off at the upper edge of the vessel K
is caught up by a fixed aunular shield which leads it into a fixed annular
trough a below, which is inclined to one side, so as to lead the sludge to a spont
at u, to be conveyed away for further treatment.
The mercury, after having taken up a sufficient quantity of gold, is discharged
through perforated plugs k,, which screw with a thread into threaded openings in
the bottom of vessel K. These plugs have a vertical perforation, terminating at
the upper end in a horizontal perforation underneath the conical head k, this
perforation being closed when the plug is screwed down, as shewn, but when the
plug is screwed upward in the hole of the vessel the ends of the perforation are
uncovered and the amalgam which has run down into the bottom of the vessel when
the rotation hereof has been stopped, can flow off through the perforations o² and of,
and is caught by an annular trough D fixed to the framing below the vessel K,
from which trough it flows into a receptacle (.
In order to maintain the mercury surface always in a condition to take up the
gold, an electric current is passed through the sludge to the mercury surface, this
being effected by connecting the lower ends of the tubes R2 supplying the elec-
trolyte from the vessel B to the lower ends of the tubes R', and which are insulated
by a caoutchouc covering, by means of wires with the positive pole of a current
generator, while the negative pole is connected with the step hearing of the
shaft A, so that the electric current will flow, as indicated by the arrows, through
the lead pipes R and through the issuing sludge to that contained in the bottom
of the vessel, from which it will then pass to the mercury surface and thence.
through the conical vessel K shaft A and bearing L back to the generator.
The oxygen given off by the resulting electrolysis is taken up by the lead, while
the hydrogen is liberated in large quantities and forms in the nascent state a
hydrogen amalgam alloy with the mercury, which, being specifically lighter than
the mercury, covers the surface hereof with a layer the thickness of which depends
upon the strength of the current, and is consequently capable of regulation.
In order to prevent the electric current from taking a different direction from
that described, or branching off, the distributing disc E is insulated by the plates i i
and ring C.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The method of effecting the amalgamation of gold and silver by the aid of
centrifugal action wherein the centrifugal force of a rotating vessel is utilized
for causing, on the one hand the mercury serving for amalgamation to be
uniformly distributed over the surface of the vessel in such manner as to be held
stationary thereon and on the other hand for causing the sludge to rise up over
the surface of such layer of mercury while at the same time the gold and silver
bearing particles are propelled by the centrifugal force from the sludge into
intimate contact with the mercury so as to become amalgamated therewith,
substantially as described.
2. For carrying out the method referred to in the preceding claim, the use of
apparatus consisting of a conical vessel K rotating on an axis A, such vessel being
open at top and closed at bottom by a rounded part, and provided on its inner
surface with circular ribs r of which the top one projects inwards more than the
others, substantially as described with the reference to the drawings.
:
3. In combination with the vessel K referred to in the preceding claim, a
distributing disc E fixed to the axis A and having radial ribs and rim b, for the
"

page_text: purpose of distributing the ore sludge upon the layer of mercury, substantially as
described.
4. In combination with the vessel K referred to in the second claim the use of a
fixed annular shield m and receiving trough n, for receiving and conveying away
the exhausted ore sludge, substantially as described.
5. In combination with the vessel K referred to in the second claim, the use of
a screwed plug ks screwed into the bottom of the vessel K such plug being
provided with a conical head and perforations o' of extending respectively vertically
through the lower part of the plug and horizontally under the conical head thereof,
through which perforations the mercury collecting in the bottom of the vessel can
be discharged on screwing the plug upward, substantially as described.
6. In centrifugal amalgamating apparatus such as is referred to in the previous
claims, connecting the positive pole of an electric current generator with insulated
supply pipes R2 for electrolytic fluid, while the negative pole is connected with the
vessel through the bearing L and shaft A, for the purpose of conveying an
electric current through the sludge passing over the layer of mercury substantially
as described.
Dated this 30th day of December 1893.
ABEL & IMRAY,
Agents for the Applicant.