and Apparatus for the Extraction, Separation, and Refining of Metals by Electrolysis.
Year: 1892

page_text: Tante),
Date of Application (in United Kingdom), 21st Sept., 1892
Complete Specification Left, 21st Jun, 1893-Accepted, 22nd July, 1893
PROVISIONAL DE DIFICATIO
Process and Apparatus for the Extraction, Separation, and Refining
of Metals by Electrolysis.
I, DONATO TOMMASI of 3, Place Daumesnil, Paris, France, Engineer, do
hereby declare the nature of this invention to be as follows:-
This invention relates to a process and apparatus for the extraction, separation,
and refining of metals by electrolysis, and it has for its object to reduce the cost
of the operation
(1) By preventing the polarization of the cathodes by making them in the form
of discs of carbon either alone or mixed with oxide of copper and causing them
to revolve so that their acting surfaces are alternately immersed in the bath and
exposed to the air, and by subjecting said surfaces to the continuous friction of
brushes for the purpose of freeing them from all adhering matters;
(2) By reducing to a minimum the electrical resistance of the electrolyte by
bringing the electrodes closer together;
(3) [a] By separating in, in the case of a binary metallic compound, the two
metals simultaneously the first by electrolysis and the second by chemical precipi-
tation by immersing in the bath, bars or ingots of the first metal which precipitates
the second and which is itself attacked by the bath so that the liquor holds in
solution only the salt of this first metal, which metal goes to increase the electrolytic
deposit and is thus recovered, so to speak, without loss; [b] by separating, in the
case of a ternary metallic compound, the three metals at one time by means of
a bath in which two only of the metals are soluble, one being electrolysed and the
other precipitated, while the third remains unattacked;
(4) By keeping the electrolyte homogeneous by the agitation due to the
revolving motion of the discs and of the bars or ingots above mentioned.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein
Figure 1 represents a longitudinal vertical section and Figure 2 a transverse
vertical section of one arrangement of the apparatus, more particularly intended
for the recovery of metal in a spongy state.
Figure 3 represents a transverse vertical section and Figure 4 a longitudinal
vertical section, of an electrolyzer designed more particularly for the treatment of
ternary alloys, such as argentiferous slags or skimmings for example.
The apparatus represented in Figures 1 and 2 for recovering metal in a spongy
state, consists of a rectangular trough A divided into compartments by a number
of perforated rectangular containers B placed a few inches apart and between
which rotate the discs E mounted upon a revolving shaft C and only partially
immersed, so that every part of the acting surface shall be alternately exposed to
the air and to the electrolyte. Each disc is caused to pass between two friction

page_text: :
1
rubbers or brushes D (Figure 2) which serve not only to remove the numerous
bubbles of hydrogen adhering thereto, but also the metallic deposit which is
received and collected in gutters by which it is conducted into receptacles for
melting. To avoid the throwing off of the metallic particles by the rotation of
the discs, the latter may be enclosed in a casing.
In treating ternary alloys such as, for example, in extracting silver from argenti-
ferous slags or skimmings in which two metals (say lead and zinc) are found in the
solution and may precipitate simultaneously upon the cathodes, it is necessary to
place on each side of the cathode discs upon the shaft C metallic bars N (of zinc
in the example supposed) of a length equal to the diameter of the discs, arranged
radially, or in the form of a cross, as shewn in transverse and longitudinal sections
in Figures 3 and 4. These bars or arms as they leave the bath are carried by
the rotation of the shaft alternately between two rubbers D in the form of brushes
for removing the lead (in the case of slags or skimmings) as it deposits upon the
zinc and conducting it into a suitable receptacle. These metal bars are not
traversed by the current from the dynamo and consequently do not act as cathodes,
but simply serve to precipitate the other metal contained in the electrolyte so as
to obtain a solution containing only the same metal as that composing the bars.
The vat A of the electrolyzers represented in Figures 1, 2, 3, and 4, may be
made either of stoneware, enamelled iron, wood lined with india-rubber, ebonite,
celluloid, or gutta-percha, etc., or coated with an insulating varnish unattackable
by the agents employed. The perforated containers B to receive the anodes are
made of ebonite, celluloid, porcelain, carbon, etc. The cathode discs E may be
made of copper, zinc, lead, aluminium, etc., or of compressed carbon, either alone
or mixed with oxide of copper, by which hydrogen is absorbed, thus avoiding the
polarization which is so detrimental in electrolysis. The brushes or rubbers D
(Figure 2) are made of inoxidizable wire, rubber, or other material, and are
provided with adjusting screws to regulate the pressure upon the discs.
The cathode discs are connected electrically through their shaft which is con-
nected to the negative conductor of the dynamo, by any suitable means such as,
for example, a metal disc C rotating in a trough of mercury H (Figures 1 and 4).
The anodes may either be made of coarse granulated material, as shewn, or in the
form of plates produced by casting the metal or ore in a suitable mould containing
a central metal strip M which is embedded in the plate and serves to receive the
binding screw to connect the anode plate with the electric conductor. When the
anode is made of granulated material, it is simply packed in the perforated con-
tainer at each side of the metallic plate M serving as conductor (Figures 1 and 4).
To ensure a good contact between the granular substances and the conductors, a
strip of the same metal is placed in the bottom of the holder.
The advantages of this electrolyzer, as compared with those now in use, may be
thus summarized :-
(1) Polarization is entirely prevented (a) by the continuous rotation of the discs
forming the cathodes (1) by the friction of the brushes against the opposite faces
of the discs, whereby the escape of the hydrogen is facilitated (c) by the presence
of oxide of copper (when the cathodes are made of carbon) which takes up the
hydrogen and becomes reduced to a metallic state. The reduced copper, being in
an extremely subdivided state, quickly takes up the oxygen of the air, especially
in presence of carbon and is converted afresh into oxide of copper which in its
turn is reduced by the hydrogen and so on indefinitely, by reason of the continual
rotation of the discs, each portion of which is bathed alternately in the liquid and
in the air.
(2) The metal precipitated upon the cathode discs is removed as fast as it is
produced. The advantages attending this mode of operation are as follows:
(a) the metal being continually withdrawn from the oxidising action of the bath
is no longer liable to be attacked and to form local couples whose current is inverse
to the principal current (b) a considerable diminution of the electrical resistance
of the bath, inasmuch as the anodes may be brought quite close to the cathodes

page_text: without the liability of short circuiting (c) economy of current, due to the
diminution of the resistance of the bath. Theoretically, the electrolytic refining
of metals involves no expenditure of mechanical energy as the quantity of heat
disengaged by a molecule of any metal entering into solution is exactly equal to
the quantity of heat absorbed by setting at liberty a molecule of the same metal
from its corresponding compound. Mechanical energy is in fact only employed to
overcome the resistance of the electrolytic solution and the polarization of the
electrodes.
(3) The density of the several layers of liquid traversed by the current is the
same throughout, owing to the continual rotation of the discs by which they are
kept constantly stirred and mixed thereby preventing the liquid from becoming
saturated towards the bottom and impoverished in the upper portion of the bath,
as is always the case where the liquid remains at rest, the intimacy of the mixture
being further ensured by the use of the metal bars to be obtained by electrolysis
for effecting the precipitation of the second metal.
My electrolyzer may be employed with advantage for the electrolytic refining of
copper, lead, zinc, nickel, silver, etc., for the recovery of the tin from tin plate
scraps; for treating argentiferous slags or skimmings, old coin, matts, speiss, etc.,
for extracting metals from their ores whether roasted or not, soluble or otherwise,
with or without soluble anodes, and particularly for the extraction of copper, zinc,
lead, antimony, nickel, etc., and for the preparation of certain chemical
products, etc.
It will be evident that the composition of the bath will be varied according to
the electrolytic operation to be performed. Thus a sulphate of copper solution
would be used for refining copper, a sulphate or acetate of zinc solution for the
refining or extraction of zinc, a lead nitrate solution for extracting lead from galena,
and so on. The composition of these various liquids being the same as usual,
needs no description. I would, however, remark that when the electrolyzer is.
employed for the extraction of silver from pig lead, pattinsonized lead, or
argentiferous slags or skimmings, the electrolyte would be of the following special.
composition of my invention:
(a) A solution, in one thousand grammes of water, of 250 grammes of caustic
potash or soda to which is added one hundred grammes of acetate of soda or
sulphate of sodium and about eighty grammes of glycerine or other organic matters
having reducing properties, such as sugar, glucose, milk sugar, etc., the former (the
alkaline salts) diminishing the electrical resistance of the bath and the second
(the organic matters) preventing the formation on the anode of peroxide of lead
which might retard and even prevent its solution in the liquid traversed by the
current.
(b) A solution of neutral acetate of lead or rendered alkaline by an excess of
caustic potash to which is also added ten per cent. of glycerine or other organic
reducing matters for the same purpose as before.
For extracting silver from argentiferous slags or skimmings, to an electrolyte of
the above composition is added a solution of neutral acetate of zinc or rendered
alkaline by an excess of caustic potash together with organic reducing matters, as
before.
1000

page_text: COMPLETE SPECIFICATION.
Process and Apparatus for the Extraction, Separation, and Refining
of Metals by Electrolysis.
I, DONATO TOMMASI of 3, Place Daumesnil, Paris, France, 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 process and apparatus for the extraction, separation,
and refining of metals by electrolysis, and it has for its object to reduce the cost of
the operation
(1) By preventing the polarization of the cathodes by making them in the form
of discs of carbon either alone or mixed with oxide of copper and causing them to
revolve so that their acting surfaces are alternately immersed in the bath and
exposed to the air, and by subjecting said surfaces to the continuous friction of
brushes for the purpose of freeing them from all adhering matters;
(2) By reducing to a minimum the electrical resistance of the electrolyte by
bringing the electrodes as close together as possible.
(3) [a] By separating, in the case of a binary metallic compound (such as zinc
and lead for example) the two metals simultaneously the first (zinc) by electrolysis
and the second (lead) by chemical precipitation by immersing in the bath, bars or
ingots of the first metal which precipitates the second (lead) and which is itself
attacked by the bath so that the liquor holds in solution only the salt of this first
metal, which metal (zinc) goes to increase the electrolytic deposit and is thus
recovered, so to speak, without loss; [6] by separating, in the case of a ternary
metallic compound, the three metals at one time by means of a bath in which two
only of the metals are soluble, one being electrolysed and the other deposited,
while the third remains unattacked and is precipitated.
(4) By keeping the electrolyte homogeneous by the agitation due to the
revolving motion of the discs and of the bars or ingots above mentioned.
Reference is to be had to the drawings accompanying my Provisional Specification,
wherein
Figure 1 represents a longitudinal vertical section and Figure 2 a transverse
vertical section of one arrangement of the apparatus, more particularly intended
for the recovery of metal in a spongy state.
Figure 3 represents a transverse vertical section and Figure 4 a longitudinal
vertical section, of an electrolyzer designed more particularly for the treatment of
ternary alloys, such as argentiferous slags or skimmings for example.
The apparatus represented in Figures 1 and 2 for recovering metal in a spongy
state, consists of a rectangular trough A. divided into compartments by a number
of perforated rectangular containers B placed a few inches apart and between
which rotate the discs E mounted upon a revolving shaft C and only partially
immersed, so that every part of the acting surface shall be alternately exposed to
the air and to the electrolyte. Each disc is caused to pass between two friction
rubbers or brushes D (Figure 2) which serve not only to remove the numerous
bubbles of hydrogen adhering thereto, but also the metallic deposit which is
received and collected in gutters by which it is conducted into receptacles for
melting. To avoid the throwing off of the metallic particles by the rotation of the
discs, the latter may be enclosed in a casing.
In treating ternary alloys such as, for example, in extracting silver from argenti-
ferous slags or skimmings in which two metals (say lead and zinc) are found in
the solution and may precipitate simultaneously upon the cathodes, it is necessary
to place on each side of the cathode discs upon the shaft C metallic bars or discs N
(of zinc in the example supposed) of a length equal to the diameter of the cathode
discs, arranged radially, or in the form of a cross in the case of bars, as shewn in

page_text: transverse and longitudinal sections in Figures 3 and 4. These bars or arms as
they leave the bath are carried by the rotation of the shaft alternately between
two rubbers D in the form of brushes for removing the lead (in the case of slags
or skimmings) as it deposits upon the zinc and conducting it into a suitable
receptacle. These metal bars are not traversed by the current from the dynamo
and consequently do not act as cathodes, but simply serve to precipitate one of the
two metals contained in the electrolyte so as to obtain a solution containing only
the same metal as that composing the bars.
The vat A of the electrolyzers represented in Figures 1, 2, 3, and 4, may be
made either of stoneware, enamelled iron, wood lined with india rubber, ebonite,
celluloid, or gutta-percha, etc., or coated with an insulating varnish unattackable
by the agents employed. The perforated containers B to receive the anodes are
made of ebonite, celluloid, porcelain, carbon, etc. The cathode discs E may be
made of copper, zinc, lead, aluminium, etc., or of compressed carbon, either alone
or mixed with oxide of copper, by the presence of which oxide hydrogen is
absorbed, thus avoiding the polarization which is so detrimental in electrolysis.
The brushes or rubbers D (Figure 2) are made of inoxidizable wire, rubber, or
other material, and are provided with adjusting screws to regulate the pressure
upon the discs.
The cathode discs are connected electrically through their shaft which is connected
to the negative conductor of the dynamo, by any suitable means such as for
example, a metal disc C¹ rotating in a trough of mercury H (Figures 1 and 4).
The anodes may either be made of coarse granulated material, as shewn, or in the
form of plates produced by casting the metal or ore in a suitable mould containing
a central metal strip M which is embedded in the plate and serves to receive the
binding screw to connect the anode plate with the electric conductor.
anode is made of granulated material, it is simply packed in the perforated container
at each side of the metallic plate M serving as conductor (Figures! and 4). To
ensure a good contact between the granular substances and the conductors, a strip of
the same metal is placed in the bottom of the holder.
When the
The advantages of this electrolyzer, as compared with those now in use, may be
thus summarized :-
(1) Polarization is entirely prevented (a) by the continuous rotation of the discs
forming the cathodes (b) by the friction of the brushes against the opposite faces
of the discs, whereby the escape of the hydrogen is facilitated (c) by the presence
of oxide of copper (when the cathodes are made of carbon) which takes up the
hydrogen and becomes reduced to a metallic state. The reduced copper, being in
an extremely subdivided state, quickly takes up the oxygen of the air, especially
in presence of carbon and is converted afresh into oxide of copper which in its
turn is reduced by the hydrogen and so on indefinitely, by reason of the continual
rotation of the discs, each portion of which is bathed alternately in the liquid and
in the air.
(2) The metal precipitated upon the cathode discs is removed as fast as it is
produced. The advantages attending this mode of operation are as follows:
(a) the metal being continually withdrawn from the oxidising action of the bath is
no longer liable to be attacked and to form local couples whose current is inverse to
the principal current (b) a considerable diminution of the electrical resistance of
the bath, inasmuch as the anodes may be brought quite close to the cathodes
without the liability of short circuiting (c) economy of current, due to the
diminution of the resistance of the bath. Theoretically, the electrolytic refining
of metals involves no expenditure of mechanical energy as the quantity of heat
disengaged by a molecule of any metal entering into solution is exactly equal to
the quantity of heat absorbed by setting at liberty a molecule of the same metal
from its corresponding compound. Mechanical energy is in fact only employed to
overcome the resistance of the electrolytic solution and the polarization of the
electrodes.
(3) The density of the several layers of liquid traversed by the current is the

page_text: same throughout, owing to the continual rotation of the discs by which they are
kept constantly stirred and mixed thereby preventing the liquid from becoming
saturated towards the bottom and impoverished in the upper portion of the bath,
as is always the case where the liquid remains at rest, the intimacy of the mixture
being further ensured by the use of the metal bars to be obtained by electrolysis
for effecting the precipitation of the second metal.
My electrolyzer may be employed with advantage for the electrolytic refining of
copper, lead, zinc, nickel, silver, etc., for the recovery of the tin from tin plate
scraps; for treating argentiferous slags or skimmings, old coin, matts, speiss, etc.,
for extracting metals from their ores whether roasted or not, soluble or otherwise,
with or without soluble anodes, and particularly for the extraction of copper,
zinc, lead, antimony, nickel, etc., and for the preparation of certain chemical
products, etc.
It will be evident that the composition of the bath will be varied according to
the electrolytic operation to be performed. Thus a sulphate of copper solution
would be used for refining copper, a sulphate or acetate of zinc solution for the
refining or extraction of zinc, a lead nitrate solution for extracting lead from
galena, and so on. The composition of these various liquids being the same as
usual, needs no description. would, however, remark that when the electrolyzer
is employed for the extraction of silver from pig lead, pattinsonized lead, or
argentiferous slags or skimmings, the electrolyte would be of the following special
composition of my invention :
(a) A solution, in one thousand grammes of water, of 250 grammes of caustic
potash or soda to which is added one hundred grammes of acetate of soda or
sulphate of sodium and about eighty grammes of glycerine or other organic matters
having reducing properties, such as sugar, glucose, milk sugar, etc., the former (the
alkaline salts) diminishing the electrical resistance of the bath and the second
(the organic matters) preventing the formation on the anode of peroxide of lead
which might retard and even prevent its solution in the liquid traversed by the
.current.
(b) A solution of acetate of lead neutral or rendered alkaline by an excess of
caustic potash to which is also added ten per cent. of glycerine or other organic
reducing matters for the same purpose as before.
For extracting silver from argentiferous slags or skimmings, to an electrolyte of
the above composition is added a solution of acetate of zinc neutral or rendered
alkaline by an excess of caustic potash together with organic reducing matters, as
.before.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is―
1st. In an electrolytic process, the employment, for preventing polarization, of
rotating disc cathodes whose acting surfaces are caused by their rotation to pass
alternately through the bath and through the air, as specified.
2nd. In an electrolytic process, the employment, for preventing polarization, of
rotating disc cathodes whose acting surfaces are caused by their rotation to pass
alternately through the bath and through the air, in combination with stationary
brushes provided with collecting gutters for detaching and collecting the metal
deposited on the cathodes in a crystalline or spongy form and removing the bubbles
of gas adhering to the cathodes, as specified.
3rd. The composition of the several electrolytes specified, for extracting any
metal associated with lead, the base in each case being a solution of the said metal
.associated with lead.
4th. The process of effecting the simultaneous separation and precipitation of
the metals in a single operation, as specified.
5th. In an electrolytic process as described, effecting the separation of the
elements of a ternary metallic compound, two of which are soluble in the electrolyte

page_text: and the third insoluble, and then separating these two metals contained in the
electrolyte as described so as to leave only in the solution the one which is to be-
electrolyzed.
6th. The improved electrolytic apparatus substantially as described and illustrated
in the drawings, consisting essentially in the combination of a cathode disc revolving.
in the electrolyte, with a rubber for removing the metal deposited thereon, as
specified.
Dated this 21st day of June 1893.
D. TOMMASI,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.