Electro-chemical Cementation for Separating Copper from Solutions by Means of Iron.
Year: 1893

page_text: Date of Application, 2nd Feh., 1893
Complete Specification Left. 21st Aug., 1893-Accepted, 4th Nov., 1893
PROVISIONAL SPECIFICATION.
Electro-chemical Cementation for Separating Copper from Solutions
by Means of Iron.
I, RAIMONDO CON EDERA, of Massamarittima, Grosseto, Italy, Engineer, do
hereby declare the nature of this invention to be as follows:
In ordinary cementation, the useful reaction almost entirely stops as soon as the
iron is covered with a very thin layer of copper; several secondary reactions then
commence which cause: 1. A large consumption of iron; 2. The oxidation of the
precipitated copper; 3. In most cases the formation of basic salts of iron, and
which render the operation very slow.
By this new system an atom of iron is substituted for each atom of copper in the
solutions under cementation, and further the electric energy which is produced by
the reaction above indicated is utilized; all the injurious secondary effects are
avoided; the operation is rendered rapid; a large economy both in iron and plant
is effected, and all the copper is obtained in a metallio and nearly pure state. ·
This electro-chemical cemontation, either intermittent or continuous, always
proceede regularly without any need of recleaning the large mass of iron until the
layer of deposited copper has attained the desired degree of thickness and
consistency.
The ordinary cementation boxes or chaunels become very powerful batteries.
In carrying out this new system the plant in present use may be utilized by
simply modifying same.
Description of the process: On the surface of the liquids under cementation, by
means of pieces of wrought or cast iron suitably arranged within the bath, a layer
of bars of wrought or cast iron serving to produce the initial or exciting electric
current aro arranged. This current which may be regulated at will can be easily
transmitted to all parts of the bath by means of graphite in powder, which is
previously introduced as will be bereinafter seen, into the liquid and which is
automatically held in suspension therein, and serves to transmit the current from
the bars on the surface to those which are arranged within the bath. In this
manner the pieces of iron which are plunged into the bath, although they may be
covered with copper and are consequently inert, become so many battery elements
connected together in quantity, and having the tension of the exciting current.
The current is regulated by keeping the bars on the surface more or less oleau.
The ferric salts ordinarly contained in copper solutions, are reduced to ferrous salts
before the cementation, by means of the metallic copper in very fine powder, which
is mixed with the graphite which is stirred into the solutions. The copper-graphite
employed is that which is obtained as a bye product from the washing of the
electro-chemically deposited copper from previous operations, the solution of the
iron (as is well known) supplying the necessary graphite.
The solutions immediately become acid on account of the acids set freo by
the copper which is deposited by the action of the electric currant.
The copper is deposited in large layers the thickness of which may be increased
as desired.
The plant is very simple and operates almost entirely automatically.
Dated thie 2nd day of Fahm 1802

page_text: COMPLETE SPECIFICATION.
Electro-chemical Cementation for Separating Copper from Solutions
by Means of Iron.
'I, RAIMONDO Conedera, of Massamarittima, Grosseto, 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:-
In ordinary cementation the useful reaction almost entirely stops as soon as the
iron is covered with a very thin layer of copper; several secondary reactions then
commence which cause: 1. A largo consumption of iron; 2. The oxidation of the
precipitated copper; 3. In most cases the formation of basic salts of iron, and
which render the operation very slow.
By this new system an atom of iron is substituted for each atom of copper in the
solutions under cementation, and further the electric energy which is produced by
the reaction above indicated is utilized; all the injurious secondary effects are
avoided; the operation is rendered rapid; a large economy both in iron and plant
is effected, and all the copper is obtained in a metallic and nearly pure state.
This electro-chemical comentation, either intermittent or continuous, always
proceeds regularly withont any need of recleaning the large mass of iron until
the layer of deposited copper has attained tho desired degree of thickness and
consistency.
The ordinary cementation boxes or channels become very powerful batteries.
In carrying ont this new system the plant in present use may be utilized by
simply modifying same.
Description of the process: On the surface of the liquids under cementation, by
means of pieces of wrought or cast iron suitably arranged within the bath, a layer
of bars of wrought or cast iron serving to produce the initial or exciting electric
current are arranged. This current which may be regulated at will can be casily
transmitted to all parts of the bath by means of graphite in powder, which is
previously introduced as will be hereinafter seen, into the liquid and which is
automatically held in suspension therein, and serves to transmit the current from
the bars on the surface to those which are arranged within the bath. In this
mauner the pieces of iron which are plunged into the bath, although they may
be covered with copper and are cousequently inert, become so many battery
elements connected together in quantity, and having the tension of the exciting
current.
The current is regulated by keeping the bars on the surface more or loss clean.
The ferric salts ordinarly contained in copper solutions, aro reduced to ferrous
Balts before the cementation, by means of the metallic copper in very fine powder,
which is mixed with the graphite which is stirred into the solutions. The copper-
graphito employed is that which is obtained as a bye product from the washing of
the electro-chemically deposited copper from previous operations, the solution of
the iron (as is well known) supplying the necessary graphite.
The solutions immediately become acid on account of the acids set free'by the
copper which is deposited by the action of the electric current.
The copper is deposited in large layers the thickness of which may be increased
as desired.
The plant is very simple and operates almost entirely automatically.
The application of the arrangement of the bars of wrought or cast iron in the
cementation boxes or channels may differ according to circumstances, but the
accompanying drawing shows a general arrangement which will enable same to
be readily understood.
In this drawing A are the bars of polished wrought or cast iron, immersed in
the ferrous sulphate, which is formed at the surface of the bath. They serve to

page_text: produce the exciting current; B are the bars of cast iron covered with a layer
of copper the thickness of which increases progressively, since they are submerged
in the copper solution which is decomposed by the electro-chemical action; Ĉ is
a wooden frame for supporting the bars at the surface.
By keeping the bars at the surface more or less clean or bright, the exciting
current may be regulated at will, such current, by means of the graphite in
suspension in the liquid, being transmitted throughout the bath and maintaining
the activity of the bars submerged in the sulphate of copper, even when the latter
are completely covered by a thick layer of metallic copper.
The graphite which I employ for transmitting the electric current through
the bath is obtained from the washing of the copper deposited in preceeding
operations.
That which is set free by the iron which is consumed in each operation, cannot
be active, for it is confined beneath the layers of copper which surround the
submerged bars.
In ordinary cementation processes, there may be graphite suspended in the
liquid; but this is the characteristic sign that the copper is not deposited in the
metallic state adhering to the iron by electro-chemical action, but in powder by
the simple substitution of an atom of iron for a molecule of copper decomposed ;
and that the energy which is developed by the reaction is lost in secondary actions,
which are nearly always prejudicial,
With the process described besides the chemical reaction of iron on sulphate of
copper, the electrical energy produced by the same reaction is also utilized, which
is clear from the fact that less than an atom of iron is consumed for an atom of
copper deposited.
"
The graphite serves to convey the electrical current through the bath, and this
is also clearly demonstrated by the fact that, when the reaction stops, which occurs
almost as soon as the submerged iron is covered with a layer of copper, the current
energetically resumes its activity, and disseminates the above named conductor
through the liquid, and keeps it in suspension therein.
The resistance of the liquid between the bars of iron constituting the electrodes
may be too great for the tension of the exciting current to overcome same, whereby
the chemical action required will be prevented or impeded, but by dividing such
resistance up into a number of parts, which taken separately may all be overcome
by the current of the tension available, the action may go on regularly without
having to reduce the distance between the electrodes.
They
The small particles of graphite suspended in the liquid in my electro-chemical
cementation boxes or channels perform precisely the service indicated.
split up the liquid separating the iron bars on the surface from those which are
submerged, into an infinite number of parts. These small particles of graphite
being movable in the liquid, become and are maintained charged at a uniform
tension, close the circuit within the box which acts as a battery, and keep the
whole of the bars which are submerged constantly active, under the exciting
influence of the initial current produced by the bars at the surface.
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 :-
The process described consisting in
1. The reduction of the ferric salts contained in copper solutions before same are
used for precipitating the copper, by means of copper-graphite resulting from the
washing of copper from previous operations, the reaction for aulplater being as
follows, Fo'O, 3 80' + Cu = 2 (FeO, SO³) + CuO, 80%, and such operation
having the double object of reducing the ferric salts to ferrous salts and to agitate
or disturb the graphite of the solutions before submitting them to electro-chemical
cementation.
2. The arrangement of a layer of bars of iron on the surface of the baths in

page_text: ordinary cementation boxes, so as to transform same into veritable electric
batteries, such bars being kept clean so that they almost immediately become
surrounded by a layer of liquid which contains ouly sulphate of iron, whereas the
submerged bars which are covered with copper, are surrounded by sulphate of
copper, and from this moment, the cementation box is under exactly the same
conditions as an electric battery with a closed circuit through the interior of the
bath, the current being produced by the following reaction, CuO, SO' + Fe = FeO,
SO+ Cu+18. 8 caloric, Fe representing an equivalent of say 28 grammes
of iron.
3. The employment of graphite in powder suspended in the liquid, to convey the
exciting current from the iron bars at the surface of the bath to the submerged
bars, or for diminishing the resistance to the passage of the current through
the bath.
2
1000
ALLISON BROS.,
Agents for the Applicant.
1