Improvements in the Manufacture of Alkali, and in Apparatus therefor.
Year: 1892

page_text: Date of Application, 21st Oct., 1892
Complete Specification Left, 21st July, 1893—Accepted, 20th Jan., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Alkali, and in Apparatus
therefor.
We JAMES HARGREAVES of Farnworth-in-Widnes, in the County of Lancaster,
Chemical Engineer, and THOMAS BIRD, of. Cressington, near Liverpool, in the
County of Lancaster, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:-
:-
The object of our present invention is to obtain alkalies in a state of high purity,
and to provide efficient apparatus therefor.
For the above purpose we subject the solution from which the alkali is to be
obtained, say chloride of sodium, to the action of an electric current, and whilst
the decomposition of the said solution is proceeding we remove continuously, or
from time to time, by means of steam, water, or both, the alkali as it is found.
The apparatus consists of a cell, in which the solution to be decomposed and the
anode are at outside of a porous diaphragm, whilst attached to or forming part of
the said diaphragm, and on the other side thereof is the cathode and incans for
causing steam water or both to act thereon. A number of cells are employed in
practice.
Dated this 20th day of October 1892.
Improvements in the Manufacture of Alkali, and in Apparatus
therefor.
We, JAMES HARGREAVES, of Farnworth-in-Widnes, in the County of Lan-
caster, Chemical Engineer, and THOMAS BIRD, of Cressington, near Liverpool,
in the same County, Electrical 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 electrolytic method of obtaining alkalies; its
objects being to increase the purity of the product and to render the apparatus
employed more efficient.
According to our improved method of obtaining alkali by electrolysis, we use
apparatus comprising a cell or vessel divided into two compartments by a porous
diaphragm, and having in one compartment, either attached to or in contact with
the porous diaphragm, a cathode of wire gauze or perforated metal; there being in
the other compartment-that is, on the side of the porous diaphragm opposite to
that adjacent to the cathode-an anode and the solution to be decomposed-say,
sodium chloride. The compartment on the cathode side of the diaphragm does not
contain liquid, except such little as may pass by filtration through the diaphragm,
or which may be introduced in the form of steam, or spray or otherwise, for the
purpose of removing the soda yielded on the surface of the cathode; the resulting
solution being drained from the compartment either continuously or from time to
D

page_text: time. The chlorine liberated in the anode compartment may be treated in any
known way.
The accompanying diagram shows a cell or vessel divided into two compartments
by a porous diaphragm arranged in accordance with our present invention, and
adapted for carrying out our said method.
The apparatus comprises a cell or vessel A containing a cell B made of a porous
compound, such as is described in the Specification filed in pursuance of our
application made 10th October, 1892, No. 18,039. Around the cell B and in
contact therewith is the cathode C of wire gauze. D is the carbon anode. E is
the solution for example, sodium chloride solution. The space F between the
vessel A and the cell B is not filled with solution, but contains steam, which is
admitted by way of the pipe A'. A is the outlet for the alkali solution-in the
present instance, caustic soda solution. G is the outlet for chlorine evolved from
the sodium chloride solution.
While the decomposition of the solution E is proceeding, the alkali (caustic 1
soda) is continuously removed from the cathode by the steam admitted through the
pipe A, which condenses on the cathode; the resultant alkali (caustic soda)
solution escaping by the pipe A2. The steam inlet may be always open, or the
steam may be admitted only from time to time. Or, instead of steam, water may
be used for removing the alkali; the water being allowed to enter and escape by 2
preference continuously, with a view to avoiding the accumulation of solution in
the space F. Or, if preferred, both steam and water may be employed for
removing the alkali, the latter being applied in the form of a jet at A³. The
chlorine escapes through the outlet G, and is dealt with in the usual way.
It will be seen that in effect the cell B is an electrolytic cell, a boundary of
which is a permeable cathode in close juxtaposition to a porous diaphragm. Any
means may be adopted for removing periodically or continuously the alkali as it is
formed.
It will be obvious that the shape of the cell may be varied, that the permeable
cathode may form only part of its boundary, and that the latter may be arranged
vertically or horizontally or in any other convenient position.
Though the
combined cathode and diaphragm described in our aforesaid previous Specification
is very suitable for use in an electrolytic cell constructed in accordance with our
present invention, we do not confine ourselves thereto.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we claim :-
.1. In the manufacture of alkali by electrolysis, the employment of a cell in part
bounded by a permeable or perforated cathode on the external and unsubmerged
surface of which the alkali is yielded and whence it may be removed either
continuously or periodically.
2. In the manufacture of alkali by electrolysis, the employment of a cell in part
bounded by a porous diaphragm attached to or in combination with a permeable or
perforated cathode on the exterior and unsubmerged surface of which the alkali is
yielded and whence it may be removed either continuously or periodically.
3. In the manufacture of alkali by electrolysis, the employment of a permeable
cathode on the external and unsubmerged surface of which the alkali is yielded,
the said surface being continuously or periodically exposed to steam or vapour
which condenses thereon and conveys away the alkali as it is formed, substantially
as herein described.
4. In the manufacture of alkali by electrolysis, the employment of a permeable
cathode on the external and unsubmerged surface of which the alkali is yielded,
and whence it is continuously or periodically removed by a spray or jet of liquid,
substantially as herein described.
5. The improved, apparatus for obtaining alkali by electrolysis, substantially as
herein described, the same comprising a vessel A, enclosing, an electrolytic cell
wholly or partially bounded by a permeable cathode C normally unsubmerged, 'a

page_text: porous diaphragm B, and an anode D immersed in the solution whence the alkali is
obtained; means being provided for enabling the alkali yielded on the outer
surface of the cathode to be removed continuously or periodically.
Dated the 21st day of July 1893.
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Chartered Patent Agent.