Improved Means applicable for Use in the Electrolysis of Salts.
Year: 1897

page_text: Date of Application, 20th July, 1897
Complete Specification Left, 20th Apr., 1893-Accepted, 20th Oct., 1898
PROVISIONAL SPECIFICATION.
Improved Means applicable for Use in the Electrolysis of Salts.
I, JAMES HARGREAVES, of Farnworth-in-Widnes, in the County of Lancaster,
Chemical Engineer, do hereby declare the nature of this invention to be as
follows;-
This invention relates to the decomposition of salts by electrolytic means, and
consists in an improved construction of diaphragm and electrode for use in elec-
trolytic cells; in an improved construction of electrolytic cell wherein the anode
is arranged as a grid and supports the salt to be decomposed; and in an improved
method of fitting the anodes in the electrolytic cell; a saturating vessel being
employed for effecting the separation of insoluble matter from the salt before
admitting the same to the electrolytic cell.
According to one part of my invention, one side of the diaphragm is composed
of a comparatively hard or dense material, the other side being formed of an
open, porous or spongy material. As the hard or dense material offers high resist-
ance to the current, it is preferable to make it as thin as practicable. With this
object, I attach the said hard or dense materials to the cathode, and I form the
said cathode of wire cloth. In constructing the diaphragm-electrode, the wire
cloth is tightly stretched upon a suitable frame. One side of the cloth is covered
with a pasty, porous or spongy substance, such as clay or paper. The hard or
dense material is then applied to the other side of the cloth; the clay or paper
serving to allow the said material to fill the meshes or openings in the cloth and
to adhere firmly to the latter, but to preserve the side of the cathode which in
working is placed furthest from the anode from being coated with such material.
If desired, perforated metal may be used for the cathode. I do not confine myself
to the use of any special materials for forming the hard or dense portion of the
diaphragm-electrode, but Portland cement will in many instances be found well
adapted to the purpose. The cement is preferably made of such consistency that
a thin but complete coating may be applied to the cathode with the aid of a brush
or trowel.
The cement may however be spread evenly in a powdered condition
upon the cathode and fixed by passing a wet brush over it. After coating the
cathode with the said hard or dense material, a covering of some material of a
soft or porous nature, such as asbestos cloth, slag wool, or the like, is caused to
adhere to the coating. When the said diaphragms are to be used in a horizontal
position, the covering of soft or porous material may be composed of loose asbestos
pulp, or some light amorphous precipitate, such as silicate of magnesia. In some
cases, I use the aforesaid soft or porous materials, or any of them, in such quantity
as to fill the space between the diaphragm and the anode or anodes. . In order to
provide for the free escape of the products of electrolysis from the surface of the
cathode, I allow a deposit of metallic oxide to form upon the said cathode before
using it; or I may deposit upon the surface of the said cathode a thin layer of
some soluble substance which when removed will leave a narrow space between
the diaphragm material and the cathode."
•

page_text: According to another part of my said invention, the anodes are placed in such
a manner that they form a kind of grid against or upon which rests the salt to be de-
composed. In cells wherein the anodes are arranged horizontally, the upper part of
the cell is made sufficiently high to form a chamber for receiving a large charge
of salt, which is dissolved, as required, by the electrolyte; the latter being allowed
to rise slightly above the level of the anodes. Steam is injected into the cells
for the purpose of heating the same and to assist in dissolving the salt. Where
the salt contains insoluble matter in any important quantity, I employ a suitably
arranged saturating vessel for effecting the settlement of the insoluble impurities,
and thereby intercepting their passage into the electrolytic cell. The weakened
liquor from the electrolytic cell is conducted to the saturating vessel by means of
a steam jet, while the saturated solution flows from the said vessel into the cell.
With a view to avoiding leakage through the sides of the anode cell at the places
where the anodes pass through them, I cast the ends of the anodes into plates of
suitable metal, such as type metal, and coat the inside of the said plates with a
thick serving of pitch, or similar material; the side of the cell being then formed
by casting cement of other suitable material inside the layer of pitch.
improved Means applicable for Use in the Electrolysis of Salts.
I, JAMES HARGREAVES, of Farnworth-in-Widnes, in the County of Lancaster,
Chemical 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 the decomposition of salts by electrolytic means, and
comprises an improved construction of diaphragm and electrode for use in elec-
trolytic cells, an improved construction of electrolytic cell wherein the anode is
arranged as a grid and supports the salt to be decomposed, and an improved
method of fitting the anodes in the electrolytic cell; a saturating vessel being
employed where necessary for effecting the separation of insoluble matter from.
the salt before admitting the same to the electrolytic cell.
In the accompanying drawings, Fig. 1 is a section of a combined diaphragm
and electrode constructed according to my invention. Fig. 2 is a part elevation
and longitudinal section of a cell of the horizontal type embodying my improve-
ments; Fig. 3 is a corresponding transverse section. Fig. 4 is an end elevation
and Fig. 5 a vertical section respectively of a vertical type of cell constructed
according to my improved method. Fig. 6 is a vertical section of a saturating
vessel adapted for employment with the improved cell when treating impure salt
or brine.
According to one part of my invention, one side of the diaphragm is composed
of a comparatively hard or dense material, the other side being formed of an
open, porous, or spongy material. As the hard or dense material offers high
resistance to the current, it is preferable to make it as thin as practicable. With
this object, the said hard or dense material may he attached to the cathode, the
said cathode being formed of wire cloth. In constructing the diaphragm-electrode,
the wire cloth a is tightly stretched upon a suitable frame and covered with a

page_text: pasty, porous or spongy substance b, such as clay or paper, adapted for tem-
porarily performing a retentive function. The hard or dense material c is then
applied to the upper surface of the porous or spongy substance or to the other
side of the cloth, the clay or paper serving to allow the said hard or dense material
to fill the meshes or openings in the cloth and to adhere firmly to the latter, but
to preserve the side of the cathode which in working is placed furthest from the
anode from being coated with such material. If desired, perforated metal may
be used for the cathode. In preparing a combined electrode and stratified dia-
phragm according to my improved method, I do not confine myself to the use of
any special materials for forming the hard or dense portion of the diaphragm,
but Portland cement will, in many instances, be found well adapted to the purpose.
The cement is preferably made of such consistency that it may be applied in the
form of a thin but complete coating with the aid of a brush or trowel; but it
may be spread evenly in a powdered condition, upon the porous or spongy sub-
stance or upon the cathode and fixed by passing a wet brush over it. After
applying the said coating of hard or dense materiale, a covering d of some
material of a soft or porous nature, such as asbestos cloth, slag wool, clay or the
like, is caused to adhere to the coating. In practice, I have found a material
composed of asbestos, with lime indurated by saturation with a solution of silicate
of soda to give good results. When the said diaphragms are to be used in a
horizontal position, the covering of soft or porous material may be composed of
loose asbestos pulp, or some light amorphous precipitate, such as silicate of mag-
nesia. In some cases, I use the aforesaid soft or porous materials, or any of them,
in such quantity as to fill the space between the diaphragm and the anode or
anodes.
In order to provide for the free escape of the products of electrolysis from the
surface of the cathode, I allow a deposit of metallic oxide to form upon the said
cathode before using it, or I may deposit upon the surface of the said cathode a
thin layer of some soluble substance which, upon being dissolved or removed,
will leave a narrow space between the material of the diaphragm and the wire
cloth forming the cathode. The deposited metallic oxide is reduced to metal by
the current and produces a rough or spongy coating on the cathode, same render-
ing the action of the cathode more prompt and effective, the escape of hydrogen
being facilitated, polarisation reduced and a larger area of the cathode exposed
for contact with the liquid.
The anodes e el are placed in such a manner that they form a kind of grid upon
or against which rests the salt to be decomposed. In cells wherein the anodes
are arranged horizontally, as shown in Figs. 2 and 3, the upper part f of the cell
is made sufficiently high to form a chamber for receiving a large charge of salt,
which is preferably charged into the cell in a solid state through the charging
aperture 7, and is dissolved as required by the electrolyte h; the latter being
allowed to rise slightly above the level of the anodes ce¹. In charging the cell
with salt, care must be taken not to disturb the electrolyte and to prevent the
ingress of salt between the anodes and the diaphragm. Steam is injected into
the cathode compartment of the cell by way of the pipe for the purpose of
heating the cell the steam tending to assist in dissolving the salt.
With a view to avoiding leakage through the sides of the anode compartment A
at the place where the anodes e e¹ pass through them, plates of suitable metal,
such as type-metal, may be cast round the ends of the anodes, the insides of the
said plates being coated with a thick serving of pitch, or similar imaterial.
In constructing a cell of the horizontal type, the mode of procedure is as
follows: A lead plate k, perforated for the reception of the ends of the anodes e e¹.
is served with a coating of pitch the side walls of the cell being formed
against the coated side of the lead plate. The several anodes are placed in posi-
tion, as shewn in Figs. 2 and 3, with their ends protruding through the unpitched
side of the lead plate, and a forming board, or sand, is so disposed between the
plates as to leave a space of the required dimensions between the pitched side

page_text: of the lead plate and the board or sand. Into this space is run the cement which
is to constitute the walls of the cell; the sides and the ends being formed simul-
taneously. Having thus constructed the upper or anode compartment A of the
cell, the lower or cathode compartment B is formed by applying a tray 'm which
may be of cast metal; the diaphragm-electrode being inserted between the two
compartments which are then secured together by means of bolts nn.
In the vertical type of cell; Figs 4 and 5, the walls of the central or anode
compartment may be formed in a similar manner. In this construction there
are two cathode compartments BB; the anodes cel in the compartment A being
disposed in the form of a grid against which the salt rests. In arranging these
anodes, the slabs of carbon are each placed at an angle to the vertical, so that
each slab overlaps the next adjacent slab; ingress of salt to the space between
the anode and the diaphragm being thereby prevented.
The extremities of the anodes e e¹ are enclosed in caps o'o'. These caps are
formed of lead or type-metal cast around such extremities, the metal occupying a
hole or holes previously drilled through the anodes and also covering their ends.
By these means, the metal which enters the holes forms rivets 02 03 whereby the
cap is held firmly in position. In cooling, the metal has a tendency to shrink
upon the carbon and thereby becomes firmly attached thereto, at the same time
forming a good electrical connection between the carbon and the cap.
The anodes ee in the horizontal cell are connected up in series by means of the
connecting bar q, while the anodes e¹ c¹ are similarly connected by the bar q¹,
the positive wire from the source of electric energy being attached to the ter-
minals r r. The anodes e e on each side of the vertical cell are connected in series
by bars qq, these bars being coupled by means of the cross bar s. The inter-
mediate or alternating anodes el el on each side of this cell are connected by
bars qq and coupled by the cross bar s¹. The bars s and s' are furnished with
terminals to which the positive wire is secured: In either construction of cell
the negative wire may be connected directly with the tray m.
In operating with the aid of the improved cell, water is supplied to the anode
compartment A, the salt, which may be in the form of crystals, being then in-
serted through the feeding orifice g. This orifice is closed by a cover fi furnished
with an annular projection f2 which dips into a water-seal, whereby the escape
of chlorine is prevented. Or leakage of chlorine through defects in the joints
of the compartment A may be obviated by producing a slight vacuum in such
compartment by means of a fan applied to the chlorine outlet. During the pro-
gress of the operation steam is injected by way of the pipe into the cathode
compartment, the resulting product issuing by way of the pipe p. When treating
salt solutions in a cell such as shown in Figs. 2 and 3, the strong brine enters the
anode compartment by way of the pipe pl while the weakened brine and chlorine
are led away by the pipe p². The pipe 2 is not required when treating pure
salt, the pipe 22 being however retained for permitting the escape of chlorine.
When treating salt solutions in a cell of the vertical type (Figs. 4 and 5), the
inlet for strong brine is preferably at the lower part of the vessel.
The weakened or exhausted brine together with the chlorine may be conveyed
by way of the pipe p² to a separating vessel; the chlorine being conducted
thence to a suitable receiver or utilized directly from said vessel.
If the salt liquor contains insoluble matter in any important quantity, the
liquid is conducted to a suitable saturating vessel for effecting the settlement
of the insoluble impurities, and thereby intercepting their passage into the elec-
trolytic cell. The saturating vessel comprises an earthenware receptacle 1) for
impure salt, same being charged through a feeding orifice D¹, and resting upon
an earthenware grid D2 D3 is the outlet for any chlorine which may be present
in the vessel. The weakened liquor from the electrolytic cell is conducted to
the saturating vessel by way of the pipe 22 and is injected into said vessel by
means of a steam jet E, while the saturated solution flows from the said vessel
by way of the pipe p into the compartment A of the cell:

page_text: The pipes employed for connecting the cells or vessels may be constructed of
vulcanite or other suitable non-conducting material.
my
Having now particularly described and ascertained the nature of said
invention, and in what manner the same is to be performed, I claim :-
1. The herein described method of preparing a combined diaphragm and
electrode for use in electrolytic cells consisting in covering wire cloth or per-
forated plate with a thin layer of temporarily retentive material, such as paper
or clay, then applying a superposed coating of hard or dense material, such as
Portland cement, and ultimately covering the latter with a soft or porous material,
such as asbestos cloth, slag wool, clay or the like, a stratified diaphragm, dense-
as to one side and porous as to the other, resulting, substantially as set forth.
2. In an electrode-diaphragm, the combination with a wire cloth cathode, such
as a, of a superposed layer of paper, clay or other temporarily retentive material b,
a coating of Portland cement and a covering d composed of asbestos, substan-
tially as and for the purposes specified.
3. In constructing a combined diaphragm-electrode, coating the cathode with
a soluble substance, which, upon the application of the superposed layers of hard
and dense material, and soft or porous materials being completed, is dissolved
or removed and leaves a narrow space between the cathode and the said hard
or dense material, substantially as described.
4. In a combined diaphragm and electrode, constructed in the manner herein
described, covering the side of the diaphragm remote from the cathode with a
soft or porous material composed of asbestos with lime indurated with a solution
of silicate of soda, substantially as set forth.
5. The herein described method of constructing electrolytic cells, consisting in
coating one side of each of a pair of lead plates with pitch, inserting the anodes
through perforations in said plates and forming the walls by casting cement
against the layer of pitch.
6. For use in the decomposition of salts by electrolysis, a saturating vessel
comprising a receptacle D furnished with a grid for supporting a quantity of
salt, a charging orifice for said salt closed by a sealed cover, an inlet for weakened
brine from the electrolytic cell beneath the grid and, at the upper part of the
vessel, an outlet for strong brine and an outlet for chlorine, substantially as and
for the purposes set forth."
7. The combination, with a saturating vessel D), of a steam jet for injecting
weakened brine beneath the grid which supports the salt, substantially as set
forth.