Improvements in or connected with Electrolytic Cells, and Diaphragms therefor.
Year: 1894

page_text: Date of Application, 17th July, 1894-Accepted, 1st S pt., 1894
UUMI LEIE DI DOITIATION.
Improvements in or connected with Electrolytic Cells, and
Diaphragms therefor.
I, CHARLES NELSON WAITE, of Rumford Falls in the United States of
America, General Manager of Works, 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:-
The diaphragms which heretofore have been employed in electrolytic cells, more.
particularly those which have been employed in cells used for the decomposition of
the alkaline chlorides in the manufacture of chlorine, quickly become injured or
destroyed by the action of the products of decomposition. In the case of the suid
production of chlorine by electrolysis, the chlorine gas which is liberated, as a result
of the treatment of the chlorides aforesaid, is highly corrosive, as is well known,
In
and its injurious action upon an ordinary diaphragm soon becomes apparent.
practice frequent replacing of the diaphragms is thus rendered necessary. Serious
explosions have resulted in cases where the injury to the diaphragm has escaped
notice, and gas generated at the negative electrode has been permitted to leak
through the diaphragm without the fact being observed, or without the place of the
leakage being discovered. The object of my invention is to provide, for use in
electrolytic cells, and more particularly in those which are employed in the pro-
duction of chlorine, or other gaseous substances, a diaphragm possessing the
requisite practical efficiency, and of inexpensive character, which shall be practically
indestructible in use. I will describe my invention and the manner in which it may
be performed with reference to the accompanying drawing, which shews in vertical
section an electrolytic cell having my invention applied thereto. The cell itself,
as shewn in the drawing is of the general character which is fully explained in the
Specification of Letters Patent granted to Ernest Arthur Le Sueur, No. 5983, and
dated 7th April 1891, but my present invention is not confined to use in a cell of
that particular character as it may be applied in connection with other forms of
cells, although it is best adapted for use in connection with cells of the type
wherein the positive electrode is above the negative electrode as in the accom-
panying drawing.
At 9 is
At 1 in the drawing is the outer vessel or tank of the cell, containing the liquid 2
in which the negative electrode 3 is immersed. The negative electrode as shewn
consists of a number of sheets of wire cloth laid together with a ring 4 preferably
of metal, applied to the upper surface thereof. At 5 is shewn the bell above the
negative electrode within which bell the positive electrode 6 is placed and by which
it is supported. The positive electrode shewn consists of a metal backing 7 in
which are fixed a number of blocks of carbon 8, 8. The said positive electrode is
partially immersed in the liquid which is within the bell, the said liquid being of
somewhat higher level than the liquid which is outside the bell, as shewn.
shewn a block which is placed underneath one side of the negative electrode for the
purpose of supporting the said negative electrode and the bell 5, in an inclined or
tilted position which facilitates the escape of the gas which is formed at the
negative electrode. At 10 is shewn an asbestos film, sheet or fabric which lies upon
the upper surface of the negative electrode 3, and at 11 is shewn a ring of earthen-
ware or other suitable material which is placed upon the upper side of the said film,
sheet or fabric 10, and at 12 is shewn comminuted matter consisting of fine sand,
broken stone, or other similar material, fine. salt or the like. The ring is, in
practice, preferably from one, to two, inches in height, and serves chiefly to retain
the comminuted material in place. The lower edge or rim of the bell bears

page_text: upon the upper surface of the ring, and the meeting surfaces of the rim and
retaining ring are fitted together so as to make a tight joint.
The sand, or other comminuted matter which is placed within the ring enters,
and, more or less, fills the interstices of the asbestos film, sheet or fabric, and also
holds it down in place upon the negative electrode, so that it cannot be floated up
or displaced by the gas generated at the said negative electrode. The backing, or
layer, of comminuted material 12 combined with the layer 10 of asbestos, or the
like, operates to prevent the passage of hydrogen gas into the anode compartment
and this is of the greatest importance, since hydrogen, mingling with the chlorine,
and passing into the receiving chambers, is liable to produce an explosion, and is
highly dangerous. If the level of the brine be kept higher within the bell than it
is in the tank or containing vessel, outside the bell, as shewn in the drawing, or if,
by other means, a greater pressure is maintained inside the bell than exists outside
the bell, all caustic products of the electrolysis are prevented from washing up
into the positive electrode compartment, and a higher degree of efficiency is
obtained.
:
A diaphragm such as is herein before described is cheap and it is comparatively
indestructible as it is not attacked by chlorine or alkali.
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 :-
1. In, or for, electrolytic cells, a diaphragmn consisting of a film, sheet or fabric
of asbestos or equivalent practically indestructible material placed against the
negative electrode and a layer of sand, or equivalent comminuted material resting
against the said film, sheet or fabric and holding it pressed against the said electrode,
substantially as hereinbefore described.
2. In, or for, electrolytic cells, a diaphragm consisting of a film, sheet or fabric
of asbestos, and a layer of sand or equivalent comminuted material overlying the
said film, sheet or fabric and supported thereupon, substantially as herein before
described.
3. In electrolytic cells the combination with positive and negative electrodes
situated one above the other, of a film, sheet or fabric of asbestos or equivalent
practically indestructible material overlying the negative electrode and a layer of
sand or equivalent comminuted material resting upon the said film, sheet or fabric,
substantially as hereinbefore described.
4. An electrolytic cell constructed or arranged substantially as hereinbefore
described and illustrated in the accompanying drawing.
Dated this 17th day of I.1. 1004
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.