Improvements in Means or Apparatus for the Obtainment of Precious Metals from Ores or Materials Containing them.
Year: 1895

page_text: Date of Application, 27th Dec., 1895-Accepted, 8th Feb., 1896
COMPLETE SPECIFICATION.
Improvements in Means or Apparatus for the Obtainment of
Precious Metals from Ores or Materials Containing them.
We LOUIS PELATAN, of 6 Cité d'Antin, Paris, in the Republic of France,
Engineer, and FABRIZIO CLERICI, of 44 Corso Magenta Milan, in the Kingdom
of Italy, 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 has for its object to provide improved means for effecting the
direct extraction of precious metals such as gold and silver from their ores, or from
any other materials containing them.
The minerals or other materials, which contain the precious metals are pulverized
and mixed with a solution of a suitable solvent which can be done in the same vat
in which the said metals are separated by means of a current of electricity, and
retained by a mercury cathode. The solvent used should be that which is the
best adapted to the nature of the materials to be treated, those preferably
employed being alkaline cyanides or chlorine, but any suitable chemical agent may
be used.
The solutions used being generally very weak, the conductivity of the bath can
be ensured by mixing with the electrolyte, an alkaline salt, preferably chloride of
sodium.
This invention, however, does not relate especially to these points, which are
only referred to in order that the present invention may be better understood.
This invention consists in an electrolytic cell constructed for facilitating the
reactions required by a particular arrangement of anodes and cathodes, and by
means whereby the liquids are kept in circulation during the electrolytic action.
In order that this invention may be readily understood we will describe it with
reference to the accompanying drawings, in which:
Figure 1 is a vertical section of the electrolytic cell, Figure 2 is a transverse
section thereof shewing the means by which the agitating anodes or the agitators
alone are moved in order to secure a continuous circulation of the electrolyte ;
Figure 3 is a plan of the cell.
Figure 4 is a modified arrangement in which the anode remains fixed whilst the
agitator is freed from all connection with the electric current.
Figure 5 is a detail view shewing the guide rollers for the agitator.
The ends of the horizontal shafts 2 rest in bearings 3 in the walls or sides of the
vat at a uniform distance from the bottom thereof and carry cylinders or light
drums 4.
The two cylinders or drums are mounted one at each extremity of the inside
of the vat. They support an endless belt or band 5 having nearly the same width
as the vat and provided with agitators 6.
The endless belt 5 may be made of a conducting material or be made of india
rubber, canvas, leather or other non-conductive material coated on its outer side
with a conductive material and it then serves as an anode, for the passage of the
electric current, or it may be made of non-conducting material such as the above
and may be in the form of trellis work with wide meshes and be caused to pass,
together with the agitating arms which it carries between the anode and the
cathode, the anode being separate from the endless belt and fixed opposite to the
cathode.

page_text: When the endless belt itself serves as an anode it may be made of, or at least
coated with iron, steel, platinum, lead, or any other suitable metal. The conductive
anodes, which are employed by preference, are made of thin steel plates.
The walls and the bottom of the apparatus are usually provided with an
insulating lining of cement, ebonite or other like material, as shown at 7, in
Figure 1 and Figure 2. When the vat is constructed of brickwork, or the like, a
lining of cement is preferable. The whole bottom of the vat should be perfectly
level and tight and covered with a cathode 8 which may be made either of
amalgamated copper, or lead plates, or of mercury.
Suitable orifices 9 are provided in the vat for the discharge of the contents of the
apparatus, when the operation is over, or whenever required.
One of the horizontal shafts 2 is connected by any suitable gear with a motor, by
which it and the drum 4 keyed thereon are rotated.
This cylinder or drum when set in motion, drives the endless belt 5- with the
result that the second drum 4 at the other end of the vat also rotates.
The gear, as shown in the drawings, consists simply of a driving pulley 10 keyed
on one of the shafts 2, outside the vat, the said pulley being rotated in the usual
way by a belt from the motor.
When the endless belt 5 serves as an anode it is connected by means of a con-
ductor 11 to the positive pole of a generator of electricity the conductor 11
transmitting the current to it by either of the shafts and drums 4 or by ordinary
friction brushes or otherwise. Another conductor 12 connects the negative pole
with the cathode 8.
When the endless belt is not employed as an anode but is only used for carrying
the agitating arms, the conductor 11 is connected to the stationary anode plate A,
Figure 4.
Suitable orifices 13 for the discharge of the mercury forming the cathode are
arranged in the bottom of the vat.
In order to maintain a proper distance between the endless belt and agitators
and the cathode, any suitable stretcher, or support, is used.
We do not confine ourselves to any special form of stretcher or support for
instance we may use a cylinder 14, made of wood, or any suitable material, the
said cylinder being set across the vat so as to support the upper portion of the
belt the said cylinder 14 being supported by racks 15 which engage with
pinions 16, mounted on a shaft 17, both ends of this shaft having handles 18, which
enable the cylinder 14 to be easily raised or lowered, or we may guide the endless
belt by rollers 19 as shewn in Figure 5. These rollers 19 are carried on wooden
or other cross pieces 20 fixed at distances apart on the belt and they run on
rails 21 arranged on the bottom of the vat. A good regulation of the tension of
the belt is of particular importance when the belt acts at the same time both as
an agitator and as an anode as explained with reference to Figures 1, 2 and 3.
The distance between the anode and the cathode should be regulated in such a
manner as to render the occurrence of any short circuiting impossible.
In the arrangement described, the agitation or rather the continued movement
of the electrolyte between the two electrodes is secured by means of the arms or
agitators 6 fixed to the belt. These arms or agitators may be made of wood, or
any other suitable non-conducting material. They are set in rows which may be
either normal to the direction of the belt or at an angle thereon, so as to prevent
the ore or the like under treatment becoming stationary on the cathode, and so
obstructing the current of electricity.
The electrolytic vat described can be made of any reasonable size, but whenever
the length of the said vat is such that one belt would be inconveniently long, there
may be arranged inside the vat two or more pairs of cylinders 4, each set of
cylinders carrying a belt similar to that described such belts being placed in
succession close one to the other, so as to cover practically the same area as the
bottom of the vat. The operation of the apparatus is as follows:-
After the preparation of the cathodes the materials to be treated are introduced

page_text: into the vat, and the necessary solvent, (for example, the alkaline cyanide) and
chloride are added, the latter ensuring the conductivity of the electrolyte. The
cyanide solutions should be used in a very diluted state. As a rule their strength
does not exceed three parts of cyanide to a thousand parts of water. The pulley 10.
is then rotated causing the shaft 2, and cylinder 4 also to rotate, and a continuous
movement to be imparted to the endless belt 5 which in turn causes the other
shaft 2, and its drum 4 to rotate.
The contents of the vat are thus thoroughly kept in movement by the arms 6.
of the belt. The current of electricity (produced from any convenient source) is
put on the negative conductor 12 being in connection with the cathode and positive
conductor 11 in connection with the anode; when the latter forms the belt the
current reaches this anode either by contact with the drums 4 or by means of the
ordinary friction brushes for example. When the belt does not form the anode.
the conductor 11 is connected with the fixed anode A.
When it has been proved, by the examination of test portions removed from the
vat, that the electrical action is completed, the said vat is emptied. The precious.
metals will then be found deposited at the cathode, and may be separated there-
from by the means usually employed or in any preferred way. The vat may then be.
at once prepared for a fresh operation.
Having now particularly described and ascertained the nature of the said inven-.
tion, and in what manner the same is to be performed, we declare that what we.
claim is :-
1. In combination with electrolytic apparatus for the extraction of precious
metals an endless belt or band provided with agitating arms and passing over
cylinders or drums or the like provided with means for imparting rotation thereto
for obtaining a continuous movement, or agitation, of the electrolyte, substantially
as hereinbefore described.
2. In combination with electrolytic apparatus for the extraction of precious
metals an endless belt or band provided with agitating arms and with means for
continually moving it, and having a conducting surface applied to its outer side
and connected to the source of electricity so as to constitute it an anode opposite,
or facing, the cathode, substantially as herein before described.
3. In combination with electrolytic apparatus for the extraction of precious
metals an endless belt or band which forms both the anode and the agitator in
combination with a mercury cathode substantially as hereinbefore described.
4. In combination with electrolytic apparatus for the extraction of precious
metals an endless belt or band carrying agitating arms and provided with means
for moving it in combination with a tension device or supporting rollers and a
cathode arranged substantially as herein before described.
5. The electrolytic apparatus as, and for the purpose, hereinbefore described
and illustrated in Figures 1, 2 and 3 of the accompanying drawings.
6. The electrolytic apparatus as, and for the purpose, hereinbefore described.
and illustrated in Figures 4 and 5 of the accompanying drawings.
Dated this 27th day of December 1895.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents..