Improvements in Treating Ores or other Substances or Liquors. Containing Gold or Silver, or both, and Apparatus therefor.
Year: 1895

page_text: Date of Application, 5th Feb., 1895
Complete Specification Left, 2nd Mar., 1895-Accepted, 6th Apr., 1895
PROVISIONAL SPECIFICATION.
Improvements in Treating Ores or other Substances or Liquors.
Containing Gold or Silver, or both, and Apparatus therefor.
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 communicated to me from abroad by Louis Pélatan of 6 Cité d'Antin, Paris
in the Republic of France, Engineer, and Fabrizio Clérici of Milan in the Kingdom
of Italy, Engineer,) to be as follows:-
This invention relates to the direct extraction of gold and silver from their ores
or any other auriferous or argentiferous materials such as matts concentrated speiss
tailings or slick residues obtained from washings or the like and has for its object
to provide an improved process and apparatus which are applicable also to the
treatment of refractory ores.
According to this invention I employ for dissolving the precious metals contained
in the ores or other materials a solution to which is added a soluble salt of an
electro positive metal for increasing the conductivity thereof and enabling an
electric current to be passed through the said solution so as to accelerate its
dissolving power and to electrolise the precious metals which are in solution on a
cathode capable of retaining the said metals.
In apparatus for carrying out the process according to this invention the cathode
employed may consist of mercury or plates of copper or silver amalgamated or
sheets of lead or other metal suitable for use with the anode employed.
The apparatus which I employ according to this invention consists of a receiver
or vat preferably of circular shape constructed of wood or other suitable material.
A vertical shaft turns in suitable bearings and rests on an insulating footstep
bearing which is fixed in the centre of the bottom of the vat. The said shaft is
provided at its lower part with metal arms or blades which may be formed straight,
or curved after the manner of a screw and are used for stirring the contents of
the vat.
The said shaft and agitating arms are formed of or plated with an electro
positive metal such for instance as iron, steel, copper, bronze, platinum, aluminium
or the like and constitute the anode while the cathode is formed as hereinafter
described.
The bottom of the vat and its inner sides may be covered up to a certain height
with amalgamated cathode plates, which are conveniently placed on a lining of an
insulating substance. When the cathode is formed in this manner, the amalgamated
plate at the bottom of the vat is provided with a large central aperture around the
central support or bearing leaving an annular space which should be kept filled
with mercury.
provided at the bottom of the vat for drawing off the
mercury and a tap discharging the contents of the apparatus.
A tap
The shaft may be rotated by any suitable transmission gear. A contact piece
bears on the said shaft to give electric connection by a conductor to the positive
pole of a dynamo or other electric generator. A second conductor connects the
negative pole of the generator to the mercury contained in the annular space of the
vat or to the amalgamated plates or to both the mercury and the amalgamated
plates. The distance between the bottom of the vat and the stirring blades should
be regulated so as to prevent the possibility of a short circuit which would interfere
with the efficient working of the apparatus.

page_text: Instead of the arrangement described the mercury may extend over the bottom
of the vat with or without a tray of amalgamated copper. Another arrangement
consists in covering the bottom of the vat with sheet-lead which then serves as the
cathode on which the gold and silver from the electrolised solutions can be
collected.
Instead of making use of an agitator as that already described an agitator may be
employed formed with plaue arms varying in size so as to impart to the anode a
greater or less surface. When this modification is adopted wooden fingers or
pieces are preferably arranged on the agitating arms. This construction of
agitator has been found very efficient in the case of vats with flat bottoms and
cathodes of mercury.
In
It is not necessary that the anode be constituted by the shaft or agitating arms;
for example, I may employ a fixed independent anode suspended in the vat.
this case the anode can be formed of a metal plate of iron, steel, bronze, or other
suitable metal and has an orifice in the middle so as to leave a free passage for the
shaft of the agitator permitting the latter to keep the solutions in a state of
agitation. The said cathode is hung somewhat above the agitator or hangers so as
to support the anode at a suitable distance from the mercury situated at the
bottom of the vat constituting the cathode.
When the vat is formed so as to present a flat bottom merely covered with
mercury and when the amalgamated plates are not placed round the sides of
the said vat orifices are made in the said sides for discharging the residues
or tailings and the solutions. A supplementary discharge pipe may be provided at
the bottom of the vat extending above the mercury which is drawn off by a special
discharge pipe arranged for that purpose.
The improved process for treating the matters containing gold or silver or both
is performed in a single operation in which three principal stages may be
noted.
(1.) Dissolving the precious metal contained in the said matters by means of a
solution such for example as a solution of cyanide of potassium, chlorine, bromine,
or the like.
(2.) The precipitation or deposition by electrolysis of the dissolved precious
metal on the cathode either in a metallic state or as an amalgam according to the
nature of the cathode.
(3.) Collecting the precious metal so precipitated or deposited.
When ores direct from mines, from concentrated masses, or from residues, or
tailings, are treated according to this process 1 employ in most cases cyanide of
potassium for dissolving the precious metals. I also find it advantageous to add a
solution of an oxidizing compound such as peroxide of potassium or sodium,
oxygenated water, or the alkaline salts which act as oxidizing agents.
The minerals in a state of fine subdivision are charged into the vat with a
sufficient quantity of the solution to form a liquid magma which can be easily
stirred by the agitator. The solution employed under ordinary circumstances
contains an amount of cyanide of potassium corresponding to about 10th of
one per cent of its weight and as in such a solution the electrical conductivity is some-
what low I find it preferable to add to it a soluble salt of a kind which will not
interfere with the process for example a salt of soda such as chloride of sodium, or
sea salt, so that the liquor is concentrated in a proportion varying according to
each particular case so as to give the desired degree of conductivity to the solution.
The agitator is now put in motion and a mild current of electricity is passed
between the anode and cathode and through the contents of the vat. The dissolving
of the precious metal commences from the start of the operation and as the precious
metal enters into solution and it forms a double salt of potassium and of gold or of
potassium and of silver or both, the electric current acts on the dissolved metals so
that the gold or silver or both is or are separated from the solution and form an
amalgam in the mercury or on the amalgamated plates or are deposited on the lead
according to the nature of the cathode that is used.

page_text: The process of amalgamation is much facilitated owing to the fact that the
cathode when formed of mercury or amalgamated plates is kept bright and clean by
the action of the electric current. The cyanide of potassium also assists in keeping
the mercury and the amalgamated plates in a condition favourable for the
amalgamating process. It appears probable that the electric current by
decomposing the alkali šalts contained in the solutions electrolizes potassium and
sodium in the mercury of the cathode and that the alkali amalgams so formed also
facilitate the amalgamation of the gold and silver.
When treating certain ores it may be found necessary to employ a solution of
liquid or gaseous chlorine in water or merely to mix with the ore and the water
substances which will set free chlorine or it may be necessary to employ a solution
of bromine or any other solution capable of dissolving gold or silver or both.
When chlorine is chosen as the dissolving agent the ore or matter to be treated
should in most cases be first thoroughly roasted especially residues or matters
containing sulphur, tellurium, arsenic or antimony.
The roasted ore or matter may be merely treated with a previously prepared
solution of chlorine or may be mixed with a suitable proportion of chloride of lime
and when the mixture has been charged into the vat the desired amount of sulphuric
hydrochloric or any other suitable acid or solution thereof is added and a uniform
liberation of chlorine is thus caused to take place through the whole mass of ore
or matter. The agitator is of course in motion from the commencement of the
operation whilst a mild current of electricity is passed from the anode to the
cathode. The chiorine thus set free dissolves the gold contained in the ore and
the gold in solution as a chloride is electrolysed to the cathode and is there
deposited or forins an amalgam.
As in the case of cyanide so when chlorine is used the solutions or liquors are
rendered better conductors by the addition of a soluble salt, notably sea salt.
When auriferous and argentiferous ores or matters are treated simultaneously by
the chlorine process the said ores or matters are previously roasted with 2 to
5 per cent. of sea salt. The ores or matters after roasting are first charged into the
vat and subjected to the action of a solution of sea salt (sodium chloride) so as to
dissolve the chloride of silver generated and after this they are treated by the
chlorine process which has been already described.
Whatever may be the dissolving agent employed for treating the auriferous and
argentiferous ores or matters the process may be interrupted after each operation
or after a series of operations in order to collect the gold amalgam or precipitate.
In the case of mercury cathodes (which are preferably used) the gold amalgam
is scraped from the cathode plates (if the cathode be formed partially of
amalgamated plates), and the bath of mercury is drawn off and the precious metal
is separated as an amalgam which may be treated in a retort.
The above described treatment may be also used for the recovery of gold and
silver from chlorinated, cyanided, brominated, or other like solutions obtained in
various processes employed for treating precious ores by the wet method. Such
solutions are charged into the vat, concentrated by the addition of a soluble salt,
stirred by the agitator and submitted to the electrolytic action employed for
amalgamating or depositing the precious metals at the cathode.
According to this invention concentrated ores, waste residues, or auriferous or
argentiferous materials may be treated and the gold or silver or both collected
therefrom (either in a metallic state or as an amalgam according to the nature of the
cathode employed) in one and the same operation, which is exceedingly simple and
rapid, each operation being capable of treating several tons of material, if the vats
be sufficiently large, and only occupying from six to twelve hours according to the
nature of the materials under treatment.
This process renders unnecessary the difficult operations of filtration of the
liquors and of lixiviation of the residues which form part of the ordinary treatment
by chlorination and cyanuration. The difficult operation of precipitating the gold
in the filtered liquors is also dispensed with. A higher yield is also obtained by

page_text: use of this process since gold in coarse grains as well as in a fine state may be
equally well recovered from the different ores which is not the case in the old
methods of cyanuration and chlorination in which the heavy gold has not time to
dissolve during the lixiviation and so is left in the residue.
With this process but small amounts of reagents are necessary as their action
is accelerated by the electric current.
The consumption of mercury when mercury cathodes are used is in this process
but small, as the electric current prevents the flouring of the mercury.
The apparatus for use with this process is simple in construction and may be
set up at a small cost, and it requires but a small amount of power to operate it,
and in consequence the nett cost for treating ores or auriferous and argentiferous
materials by this process is considerably less than in other processes.
By this process ores may be successfully and readily treated, which have not
hitherto been capable of treatment either by chlorination or cyanuration such for
instance as certain ores having an argillaceous or tale gangue which after roasting
and treating with liquid, form an impermeable paste refractory to lixiviation either
with cyanide of potassium or any other reagent. Other ores containing gold
almost entirely in grains sufficiently large to render them incapable of being
dissolved completely in a reasonable time in a solution of cyanide of potassium or
chlorine, may be treated with success and rapidity by this process since the grains
of gold which are too large to be capable of being rapidly dissolved by the solution
employed, drop to the bottom of the rat where they cannot escape the action of
the mercury cathode which is kept clean and bright by the electric current.
Although it is believed that the apparatus described, is the best for the purpose
of carrying this invention into effect, my correspondents do not limit themselves,
in conducting the process according to this invention, to the use of apparatus
constructed or arranged precisely as described and illustrated.
Dated this 5th day of February 1895.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents..
Improvements in Treating Ores or other Substances or Liquors
Containing Gold or Silver, or both, and Apparatus therefor.
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 communicated to me from abroad by Louis Pélatan, 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 relates to the direct extraction of gold and silver from their ores
or any other auriferous or argentiferous materials such as matts concentrated speiss
tailings or slick residues obtained from washings or the like and has for its object
to provide an improved process and apparatus which are applicable also to the
treatment of refractory ores.
According to this invention I employ for dissolving the precious metals contained
in the ores or other materials a solution to which is added a soluble salt of an
electro positive metal for increasing the conductivity thereof and enabling an
electric current to be passed through the said solution so as to accelerate its
dissolving power and to electrolize the precious metals which are in solution on a
cathode capable of retaining the said metals.
In apparatus for carrying out the process according to this invention the cathode

page_text: employed may consist of mercury or plates of copper or silver amalgamated or
sheets of lead or other metal suitable for use with the anode employed.
In order that this invention may be clearly understood I will refer to the
accompanying drawings which illustrate apparatus made according to this
invention for carrying the same into effect.
Figure 1 is a vertical section of an apparatus for use with this improved process.
Figure 2 is a vertical section of a modification.
Figure 3 is a plan of Figure 1.
Figure 4 is a vertical section shewing a different arrangement of anode.
Figures 5 and 6 are a vertical section and a plan respectively of another
modification shewing a stationary anode.
Like letters of reference indicate corresponding parts in all the figures.
1 is a receiver or vat preferably of circular shape constructed of wood or other
suitable material. A vertical shaft 2 turns in suitable bearings and rests on an
insulating footstep bearing 3 which is fixed in the centre of the bottom of the vat.
The said shaft is provided at its lower part with metal arms or blades 4 which
may be formed straight or curved after the manner of a screw and are used for
stirring the contents of the vat.
The said shaft 2 and agitating arms 4 constitute the anode and are formed of or
plated with an electro positive metal preferably cast carburetted iron or iron, steel,
copper, bronze, platinum, aluminium or the like may be used, while the cathode is
formed as hereinafter described.
The bottom of the vat as shown in Figure 1 and its inner sides may be covered
up to a certain height with amalgamated cathode plates, which are conveniently
placed on a lining 6 of an insulating substance. When the cathode is formed in
this manner, the amalgamated plate at the bottom of the vat is provided with a
large central aperture around the central support or bearing 3 leaving an annular
space 8 which should be kept filled with mercury. A tap 9 is provided at the
bottom of the vat for drawing off the mercury and a tap 10 discharging the contents
of the apparatus.
The shaft 2 may be rotated by any suitable transmission gear that shown in the
drawings in Figure 1 consisting of a horizontal shaft 12 with bevelled wheel 13
gearing with a second bevelled wheel 14 fixed on the upper end of the shaft 2. A
contact piece bears on the said shaft 2 to give electric connection by a conductor 15
to the positive pole of a dynamo or other electric generator. A second conductor 16
connects the negative pole of the generator to the mercury contained in the annular
space 7 of the rat 1 or to the amalgamated plates 5 or to both the mercury and
the amalgamated plates. The distance between the bottom of the vat and the
stirring blades should be regulated so as to prevent the possibility of a short
circuit which would interfere with the efficient working of the apparatus.
Instead of the arrangement shown in Figure 1 the mercury may extend over
the bottom of the vat with or without a tray of amalgamated copper shewn at 17
in Figure 2. Another arrangement consists in covering the bottom of the vat
with sheet lead which theu serves as the cathode on which the gold and silver from
the electrolized solutions can be collected.
Instead of making use of an agitator as that already described with reference to
Figure 1 an agitator may be employed formed with plane arms varying in size so
as to impart to the anode a greater or less surface. When this modification is
adopted wooden fingers or pieces are preferably arranged on the agitating arms as
shown at 4 in Figures 2, 4 and 5. This construction of agitator has been found
very efficient in the case of vats with flat bottoms and cathodes of mercury.
It is not necessary that the anode be constituted by the shaft or agitating arms,
for example a fixed independent anode may be employed suspended in the vat.
In this case the anode can be formed of a metal plate 18, of iron, steel, bronze,
or other suitable metal and has an orifice in the middle so as to leave a free passage
for the shaft of the agitator permitting the latter to keep the solutions in a state of
agitation. The said cathode is hung somewhat above the agitator on hangers 19

page_text: so as to support the anode at a suitable distance from the mercury situated at the
bottom of the vat constituting the cathode.
When the vat is formed so as to present a flat bottom merely covered with
mercury and when the amalgamated plates are not placed round the sides of the
said vat orifices 21 are made in the said sides for discharging the residues or
tailings and the solutions. A supplementary discharge pipe 10 may be provided at
the bottom of the vat extending above the mercury which is drawn off by a special
discharge pipe 9 arranged for that purpose.
The improved process for treating the matters containing gold or silver or
both is performed in a single operation in which three principal stages may be
noted.
(1.) Dissolving the precious metal contained in the said matters by means of a
solution such for example as a solution of cyanide of potassium, chlorine, bromine,
or the like.
(2.) The precipitation or deposition by electrolysis of the dissolved precious
metal on the cathode either in a metallic state or as an amalgain according to the
nature of the cathode.
(3.) Collecting the precious metal so precipitated or deposited.
When ores direct from mines, from concentrated masses, or from residues, or
tailings, are treated according to this process 1 employ in most cases cyanide of
potassium for dissolving the precious metals. I also find it advantageous to add a
solution of an oxidizing compound such as peroxide of potassium or sodium
oxygenated water, or the alkaline salts which act as oxidizing agents.
The minerals in a state of fine subdivision are charged into the vat with a
sufficient quantity of the solution to form a liquid magma which can be easily
stirred by the agitator. The solution employed under ordinary circumstances
contains an amount of cyanide of potassium corresponding to about oth of
one per cent. of its weight and as in such a solution the electrical conductivity is
somewhat low it is found preferable to add to it a soluble salt of a kind which will
not interfere with the process for example a salt of soda such as chloride of sodium,
or sea salt, so that the liquor is concentrated in a proportion varying according to
each particular case so as to give the desired degree of conductivity to the solution.
The agitator is now put in motion and a mild current of electricity is passed
between the anode and cathode and through the contents of the vat. The dis-
solving of the precious metal commences from the start of the operation and as the
precious metal enters into solution and it forms a double salt of potassium and of
gold or of potassium and of silver or both, the electric current acts on the dissolved
metals so that the gold or silver or both is or are separated from the solution and
form an amalgam in the mercury or on the amalgamated plates or are deposited on
the lead according to the nature of the cathode that is used.
The process of amalgamation is much facilitated owing to the fact that the
cathode when formed of mercury or amalgamated plates is kept bright and clean
by the action of the electric current. The cyanide of potassium also assists in
keeping the mercury and the amalgamated plates in a condition favourable for the
amalgamating process. It appears probable that the electric current by decom-
posing the alkali salts contained in the solutions electrolizes potassium and sodium
in the mercury of the cathode and that the alkali amalgams so formed also facilitate
the amalgamation of the gold and silver.
When treating certain ores it may be found necessary to employ a solution of liquid
or gaseous chlorine in water or merely to mix with the ore and the water substances
which will set free chlorine or it may be necessary to employ a solution of bromine
or any other solution capable of dissolving gold or silver or both.
When chlorine is chosen as the dissolving agent the ore or matter to be treated
should in most cases be first thoroughly roasted especially residues or matters
containing sulphur, tellurium, arsenic or antimony.
The roasted ore or matter may be merely treated with a previously prepared
solution of chlorine or may be mixed with a suitable proportion of chloride

page_text: of lime and when the mixture has been charged into the vat the acsired
amount of sulphuric hydrochloric or any other suitable acid or solution thereof is
added and a uniform liberation of chlorine is thus caused to take place through
the whole mass of ore or matter. The agitator is of course in motion from
the commencement of the operation whilst a mild current of electricity is passed
from the anode to the cathode. The chlorine thus set free dissolves the gold
contained in the ore and the gold in solution as a chloride is electrolysed to the
cathode and is there deposited or forms an amalgam.
As in the case of cyanide so when chlorine is used the solutions or liquors are
rendered better conductors by the addition of a soluble salt, notably sea salt.
When auriferous and argentiferous ores or matters are treated simultaneously by
the chlorine process the said ores or matters are previously roasted with 2 to 5 per
cent. of sea salt. The ores or matters after roasting are first charged into the
vat and subjected to the action of a solution of sea salt (sodium chloride) so as
to dissolve the chloride of silver generated and after this they are treated by the
chlorine process which has been already described.
Whatever may be the dissolving agent employed for treating the auriferous and
argentiferous ores or matters the process may be interrupted after each operation
or after a series of operations in order to collect the gold amalgam or precipitate.
In the case of mercury cathodes (which are preferably used) the gold amalgam is
scraped from the cathode plates (if the cathode be formed partially of amalgamated
plates), and the bath of mercury is drawn off and the precious metal is separated as
an amalgam which may be treated in a retort.
The above described treatment may be also used for the recovery of gold and
silver from cholrinated, cyanided, brominated, or other like solutions obtained in
various processes employed for treating precious ores by the wet method. Such
solutions are charged into the vat, concentrated by the addition of a soluble salt,
stirred by the agitator and submitted to the electrolytic action employed for
amalgamating or depositing the precious metals at the cathode.
According to this invention concentrated ores, waste residues, or auriferous or
argentiferous materials may be treated and the gold or silver or both collected
therefrom (either in a metallic state or as an amalgam according to the nature of
the cathode employed) in one and the same operation, which is exceedingly simple
and rapid, each operation being capable of treating several tons of material, if the
vats be sufficiently large, and only occupying from six to twelve hours according to
the nature of the materials under treatment.
Our process renders unnecessary the difficult operations of filtration of the
liquors and of lixiviation of the residues which form part of the ordinary treatment
by chlorination and cyanuration. The difficult operation of precipitating the gold
in the filtered liquors is also dispensed with. A higher yield is also obtained by
use of this process since gold in coarse grains as well as in a fine state may be
equally well recovered from the different ores which is not the case in the old
methods of cyanuration and chlorination in which the heavy gold has not time to
dissolve during the lixiviation and so is left in the residue.
With this process but small amounts of reagents are necessary as their action is
accelerated by the electric current.
The consumption of mercury when mercury cathodes are used is in this process
but small, as the electric current prevents the flouring of the mercury.
The apparatus for use with this process is simple in construction and may be set
up at a small cost, and it requires but a small amount of power to operate it, and in
consequence the net cost for treating ores or auriferous and argentiferous materials
by this process is considerably less than in other processes.
By this process ores may be successfully and readily treated, which have not
hitherto been capable of treatment either by chlorination or cyanuration such for
instance as certain ores having an argillaceous or talc gangue which after roasting
and treating with liquid, form an impermeable paste refractory to lixiviation either
with cyanide of potassium or any other reagent. Other ores containing gold almost

page_text: entirely in grains sufficiently large to render them incapable of being dissolved
completely in a reasonable time in a solution of cyanide of potassium or chlorine
may be treated with success and rapidity by this process since the grains of gold
which are too large to be capable of being rapidly dissolved by the solution
employed, drop to the bottom of the vat where they cannot escape the action of the
mercury cathode which is kept clean and bright by the electric current.
Although it is believed that the apparatus described is the best for the purpose
of carrying this invention into effect iny correspondents do not limit themselves in
conducting the process according to this invention to the use of apparatus
constructed or arranged precisely as described and illustrated.
Having now particularly described and ascertained the nature of this said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The improved process for obtaining gold or silver or both from ores, residues
or tailings or other auriferous and argentiferous materials, the said process consisting
in adding to the ores or materials a very weak solution of chlorine, bromine, or
cyanide of potassium, or the like, mixed, or not, with an oxidizing body, such as
peroxide of potassium or of sodium, oxygenated water, or the like, the electric
conductivity of the solution being increased by the addition of a soluble salt of an
electro-positive metal such for example as chloride of sodium, and then passing
through the contents of the vat whilst agitated a current of electricity so as to
cause the precious metal to be deposited at the cathode from which it is afterwards
recovered, all substantially as herein before described.
"
2. The improved process for electrically treating cyanated, chlorinated, or
brominated or the like auriferous and argentiferous solutions, arising from th
treatment of gold and silver bearing ores in the wet way, for recovering th
precious metal contained therein the said process consisting in increasing
the electrical conductivity of the solutions by the addition of an electro positiv
metal such as chloride of sodium for example and then passing through the
solution thus prepared a current of electricity to cause the deposition of the precious
metal at the cathode from which it is afterwards recovered substantially as
herein before described.
3. The apparatus for the purpose described, the said apparatus consisting of a
vat provided with a rotating shaft and agitator constituting the anode and the
bottom of the said vat (and if desired a portion of the sides) constituting a
cathode by being lined with an electro-negative metal such as lead or covered
with mercury or provided with copper or silver amalgamated plates and with a
central mercury bath all substantially as hereinbefore described and illustrated
by the accompanying drawings.
4. The several arrangements of apparatus herein before described and illustrated
in Figures 1 and 3, Figure 2, Figure 4 and Figures 5 and 6 of the accompanying
drawings for the purpose described.
Dated the 2nd day of March 1895.
JOHNSONS & WILLCOX,
Agents.