Improvements in Apparatus for the Electrolytical Separation of Precious Metals from their Ores or other Materials containing them.
Year: 1895

page_text: Date of Application, 12th June, 1895-Accepted, 13th July, 1895
COMPLETE SPECIFICATION.
Improvements in Apparatus for the Electrolytical Separation of
Precious Metals from their Ores or other Materials containing them.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of London,
Gentleman do hereby declare the nature of this invention (which has been com-
municated to me from abroad by Louis Pelatan of 6 Cité D'Antin, Paris in the
Republic of France, Engineer, and Fabrizio Clerici of Milan in the Kingdom
of Italy, Engineer) 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 a means for effecting the direct
extraction of the precious metals such as gold and silver from their minerals or from
any other materials containing them.
In this process the minerals or other materials which contain the precious metals
are pulverised and mixed with a solvent in the same vat in which the metals are
separated by means of a current of electricity and retained by a mercury cathode ;
the solvent used is that which is best suited to the nature of the materials to be
treated those preferably employed being alkaline cyanides or chlorine but any
other suitable chemical agent may be used.
The conductivity of the bath is ensured by mixing with the electrolyte an
alkaline salt preferably chloride of sodium. This invention however does not relate
especially to these points which have already been described in the Specification of
the prior Patent No. 1514 and dated 22nd Jany. 1895 and which are only referred
to here in order that the present invention may be better understood.
The said invention consists in an electrolytic vat constructed for facilitating the
reactions required by a particular arrangement of anodes and cathodes and by the
manner in which the liquids are kept in circulation during the electrolytic action.
In order that the invention may be readily understood I will describe it with
reference to the accompanying drawings in which
Figure 1 is an elevation partly in section of the electrolytic vat,
Figure 2 is a transverse section showing the manner in which the anodes are set
in motion in order to secure the continued agitation of the electrolyte.
Figure 3 is a modification of the apparatus in which the circulation of the
electrolyte is caused to take place round fixed electrodes by the action of centrifugal
pumps.
Figure 4 is a plan view of the vat showing the different parts thereof in which
the two devices for causing the circulation of the liquids being treated electrically
are arranged alternately.
Figure 5 shows the passage through the wall of the vat for the shafts operating
the rotating anodes.
Figure 6 is a section taken on the line ab Figure 5 showing the connection of
an agitating anode with its motor shaft.
Figures 7 and 8 show in section and end view the means by which the liquid
forced under the pressure of the circulation pumps enters the vat.
The vat 1 is preferably raised from the ground so as to facilitate the withdrawal
of the liquids therefrom and may be made of brickwork or the like its inner walls
being coated with cement.
The ends of the horizontal shafts 2 rest on bearings 3 fixed in the walls of the
vat at a certain uniform distance from the bottom thereof and support metal
cylinders 4 provided with agitators 5. These cylinders are mounted preferably in
sets: they are shown in sets of four for example in the drawings, and between the
D .
27

page_text: sets are two plates 6, mounted on supports 7 fixed or not in the masonry of the
vat 1. The shafts 2, the cylinder 4 and the plates 6 are formed of or are coated
with an electro-positive metal such as iron, steel, platinum or any other analogous
metal the cylinders. and the plates being employed as anodes while mercury or
amalgamated plates or other suitable metallic plates arranged at the bottom of the
vat act as cathodes. The anodes which are employed by preference are made of
cast iron.
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 8 in Figures 1
and 2. When the vat is constructed of brickwork or the like a lining of cement is
preferable. The bottom of the vat is provided with dips or depressions arranged
horizontally each dip extending across the whole breadth of the vat and occupying
a certain portion of the length thereof.
The cathodes 10 are in these depressions which are separated from each other
by low partitions or sills 9 formed of cement. When mercury cathodes are
employed which is in most cases preferable they are formed by plates covered with
mercury fixed at the bottom of each depression; if desired the mercury may be
spread right over the bottom of the vat in which case however it is recommended
that floating plates of amalgamated copper be arranged on the surface of the
mercury. Suitable orifices for the discharge of the contents of the apparatus are
arranged in the vat.
The horizontal shafts 2 may be rotated by any suitable means those which 1 have
shown consisting of a horizontal shaft 12 provided with bevel wheels 13 gearing
with the bevel wheels 14 fixed on the ends of the said shafts 2. The shafts 2 and
the plates 6 are connected by means of a conductor 15 to one of the poles say
the positive pole of a generator of electricity such as a dynamo. Another
conductor 16 connects the other pole, that is the negative pole of the generator
to the mercury cathodes.
The distance between the plates and the cylinders forming the anodes on the one
hand and the bottom of the vat where the cathodes are fixed on the other hand
should be such as to render short circuiting impossible which if it took place would
prevent the satisfactory working of the apparatus.
In the arrangement shewn the agitation is effected by means of the anode
cylinders provided with agitating arms the said arms being made of wood or any
other suitable insulating material.
The agitators on the adjacent cylinders are arranged to alternate with each other
as shewn clearly in Figure 4 so as to secure the perfect agitation of the material
under treatment.
If this precaution were neglected the material under treatment would accumulate
on the bottom of the vat which covering the cathodes would obstruct the current
of electricity and so prevent the proper electrolytic action. The cylinders consti-
tuting the anodes may be all rotated in the same direction or in opposite directions
to each other.
Another means of agitation which may be employed in combination with that.
described consists in the employment of powerful liquid or gaseous currents.
For this purpose a centrifugal pump 17 is provided. A feed pipe 22 passes
from the pump into the vat and dips into the liquid contained therein. The pipe 11
of the said pump 17 by which the liquid is forced back is divided into several
small pipes (four are shewn in the drawings) which are each fitted with an outlet
nozzle 18.
These outlet nozzles open into the vat beneath the anode plates 6 so as to ensure
the perfect agitation of the material being treated.
The pump may be operated by a belt 21 passing over a pulley keyed onto the
shaft.12. By this means the mass of liquid contained in the vat is drawn in by the
pipe 22 and forced through the said vats by the nozzles 18. The jets of liquid.
from these nozzles produce a thorough agitation and stirring through the whole
liquid ensuring a perfect mixing of the materials and preventing them being

page_text: deposited. In order to obtain a good effect from the jet of quid a screw-threaded
rod 19 is mounted by means of a centre pin 20 in each nozzle 18..
The pipe 22 terminates in a rose 23 so as to intercept matter likely to clog the
pump.
The action of the pumps may be so arranged that the anode plates 6ª Figure 4
may be joined and rest at one end on the vat while leaving at the other end of the..
said vat a space for the circulation of the liquids. The liquid will then be drawn
in by the suction pipe 22 of the pump and will circulate through the vat in the
direction shown by the arrows in Figure 3 that is to say the liquid will be with-
drawn from the vat at the upper part thereof and will be forced in by the nozzles 18
beneath the anodes 6. The liquid will thus be continually displaced from below
between the two electrodes. The anode plates may also be disposed as shown
at 6° Figure 4 in which an easy passage is left for the liquid between the adjacent
sides of two plates as well as at their ends. In this case a sort of eddy or whirlpool
will be imparted to the liquid instead of the regular circulation I have described
with reference to the plates shewn at 6" in Figure 4.
I have shown in the drawings one pump employed for each pair of anode plates
and feeding four distributing pipes or nozzles 18 but I do not limit myself to the
nature of the injection apparatus which may be of any suitable kind nor to the
number of nozzles employed or to their general arrangement, operation or mechanism
for working them. The pump 17, for example, may be replaced by any other
arrangement for injecting a liquid under pressure through the pipes or nozzles 18.
Or in place of the pump 17 there may be employed a ventilator or fan or a com-
pressed air apparatus and force through the vat air or other suitable gas under
pressure so as to produce the required agitation.
The operation of the apparatus is as follows:-
The auriferous and argentiferous materials held in suspension in the liquid are
introduced into the vat for which the mercury cathodes have been already prepared
as hereinbefore described. The necessary solvent, for example, alkaline cyanide is
then added to the liquid and some common salt for ensuring the conductivity of the
electrolyte. The bevel gear 13, 14, is then caused to rotate the shafts 2 with the
anodes and the centrifugal pumps 17 are also put into operation. The contents
of the vat are thus thoroughly stirred up and a current of electricity is passed
through by means of the conductors 15, 16. 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
on the mercury cathodes and may be then separated from this metal by the means
usually employed. The vat may then be prepared for a fresh operation. The
solutions of cyanides employed are weak solutions not generally exceeding 3 parts
of cyanide to 1000 parts of water.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In the electrolytic extraction of precious metals by the direct action of a
current of electricity on a suitable electrolyte containing either in suspension the
materials to be treated or auriferous and argentiferous liquors previously prepared,
the employment of an electrolytic vat with cathodes situated at the bottom thereof
the liquids subjected to the action of the current of electricity being kept in
constant agitation by the rotation of the anodes substantially as described.
2. In the electrolytic extraction of precious metals by the direct action of a
current of electricity on a suitable electrolyte containing either in suspension
the materials to be treated or auriferous and argentiferous liquors previously
prepared the employment of an electrolytic vat with cathodes situated at the
bottom thereof the anodes being fixed opposite the cathodes and the liquors
being kept constantly in movement by the action of a pump or any other
equivalent means substantially as hereinbefore described.

page_text: 3. In the electrolytic extraction of precious metals by the direct action of a
current of electricity on a suitable electrolyte containing either in suspension the
materials to be treated or auriferous and argentiferous liquors previously prepared
the employment of an electrolytic vat with mercury cathodes situated at the
bottom thereof the said liquors being kept in movement by the rotation of the
anodes or a part of them combined with the action of the pumps or their equivalents
substantially as herein before described.
4. The improved apparatus for the electrolytical separation of precious metals
substantially as hereinbefore described and illustrated in the accompanying
drawings.
Dated this 12th day of June 1895.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.