Improvements in Manufacturing Caustic Alkali from Alkali Metal Amalgams, and Apparatus therefor.
Year: 1899

page_text: Date of Application, 1st May, 1899
Complete Specification Left, 1st Feb., 1900-Accepted, 3rd Mar., 1900
PROA ISIUNAL SPECIFICATION,
PROA ISIONAL SIECIFICATION,
Improvements in Manufacturing Caustic Alkali from Alkali Metal
Amalgams, and Apparatus therefor.
1. Jostan WYCKLIFFE KYNASTON, of Oak Terrace, Beech Street, Liverpool,
in the County of Lancaster, Analytical Chemist, do hereby declare the nature of
this invention to be as follows:-
: —
The production of caustic alkalies by the medium of alkaline metal amalgam
obtained by the electrolytic decomposition of solutions of alkaline chlorides with a
mercury cathole is carried out on an extensive scale and many and varied forms of
apparatus have been designed for this purpose. In most of these arrangements
the alkali metal amalgam is caused to pass from the compartment in which it has
been produced to a second or more compartments containing water, in which it is
partially denuded of alkali metal and then returned to the first compartment to
receive a fresh charge of alkali metal.
The construction of plant of this kind in which two distinct and essentially
varying operations are to be performed is very difficult, and the second operation
-the denuding of the amalgam of alkali metal-is never completely effected,
and only very minute quantities of alkali are obtained at each circulation of the
amalgam through the denuding compartment. And by reason of the compli
cations involved in the construction of this combined apparatus it has not been
found possible to build it of sufficiently large size to obtain from one instalment
of apparatus more than a limited quantity of caustic alkali in proportion to the
size of the apparatus.
My improved form of denuding apparatus is designed to overcome these
difficulties and impediments and to permit of the perfect denudation of large
quantities of amalgam in a comparatively limited space and to use an amalgam
much richer in alkali metal than has been heretofore treated. I use as the outer
enclosure of the apparatus a tank or cistern built up of wrought or cast iron
plates firmly bolted together to form a water tight vessel. In the simplest form
of the apparatus which I have designed, the approximate internal dimensions
of the enclosure will be as follows: the height about half the length and the
breadth about one sixth of the length. For instance, in an enclosure of which
the length is ten feet, I make the height five to six feet and the breadth one foot
nine inches to two feet. I do not of course bind myself to these dimensions.
Upon each of the sides of such an enclosure, and running the entire length. I
arrange horizontally a series of shelves of iron or other suitable material at a
distance of a few inches from each other. the uppermost shelf being about one
foot from the top of the enclosure and the lowest three or four inches from the
bottom. The shelves are hollowed out on the upper surface to the depth of
about one-half inch, the depression reaching to within one-quarter inch of the
edges of the shelves. At the alternate ends of each of adjacent shelves and three
inches from the ends, a ridge, about one inch wide and one-eighth of an inch lower
than the upper edge of the shelf. runs across it and in the depression beyond the
ridge, a hole, about one inch in diameter, is bored through the shelf. Holes are

page_text: also provided through each of the sides or ends of the enclosure at a short dis-
tance above the level of the uppermost of the shelves and pipes for the con-
veyance of amalgam to the shelves are firmly fixed in the apertures. A hole is
also provided in the bottom plate of the enclosure and in this a pipe is firmly
and tightly fixed. This pipe serves for the withdrawal of the denuded mercury
from the enclosure. Pipes or tubes are also provided for passing water into the
enclosure and for drawing off the solution of caustic alkali when sufficiently con-
centrated and an orifice in the cover of the enclosure permits of the escape of
the hydrogen gas produced during the oxydation of the alkali metal in the
amalgam.
I suspend, through apertures in the cover of the enclosure, in the central space
between the shelves, a series of plates or sheets of iron which may be perforated
or in the form of grids. These exiend from about the level of the uppermost
shelf to within a short distance from the bottom of the enclosure and the sus-
penders must be carefully insulated where they pass through the cover of the
enclosure. They form the cathode element in relation to which the amalgam is
the anode and the arrangement constitutes a powerful voltaic battery.
I extend the denuding capacity of the apparatus, if desired, exactly upon the
same principles as above described. The width of the enclosure is increased to
the requisite extent, and in addition to the two series of side shelves, 1 fix, in
the centre of the space between the side shelves, a third series of shelves, the
breadth of each of which is the sum of the width of two of the side shelves. lu
this duplicate arrangement, two sets of cathode plates are employed and are
suspended in the spaces between each of the series of side shelves and the central
series of shelves. It is evident that in the same way, the power of the apparatus
may be still further augmented.
In starting the manufacture of solution of caustic alkali by this process, the
vessel is first filled with water to a little over the level of the uppermost shelf.
The liquid amalgam is then passed in and, falling upon the uppermost shelf of
each series, it fills the depression and then falls through the opening at the
further end to the next shelf and so on until all the shelves are charged when.
the stream being continued, it falls to and covers the bottom of the vessel, and
the mercury is completely or almost completely denuded of alkali metal, and
allowed to flow out of the vessel. The hydrogen gas liberated passes away by
the aperture provided for the purpose. The electric current is led away to per-
form any useful work.
Improvements in Manufacturing Oaustic Alkali from Alkali Metal
Amalgams, and Apparatus therefor.
1. Josta WYCLIFFE KYNASTON. of Oak Terrace, Beech Street, Liverpool,
in the County of Lancaster, Analytical Chemist, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particu
larly described and ascertained in and by the following statement:-
The manufacture of caustic alkalis by the medium of alkali metal amalgam.
obtained by the electrolytic decomposition of solutions of alkaline chlorides with
a mercury cathode, is carried out on an extensive scale and many and varied forms
of apparatus have been designed for this purpose. In most of these arrange

page_text: ments, the alkali metal amalgam is caused to pass, from the compartment in
which it has been produced, to a second or more compartments of the same piece
of apparatus. These second compartments are supplied with water and in them
the amalgam is partially denuded of alkali metal and then returned to the first
compartment to receive a fresh charge of alkali metal.
The construction of plant of this kind, in which two distinct and essentially
varying operations are to be performed. is very difficult and the second operation
-the denuding of the amalgam of alkali metal-is never completely effected
and only very minute quantities of alkali are obtained at each circulation of the
amalgam through the denuding compartment, and by reason of the compli
cations involved in the construction of this combined apparatus, it has not been
found possible to build it of sufficiently large size to obtain, from one instalment
of apparatus more than a very small quantity of caustic alkali in proportion to
the size of the apparatus.
My improved form of denuding apparatus is designed to overcome these diffi-
culties and impediments and to permit of the perfect denudation of large quantities
of amalgam in a comparatively limited space and to use an amalgam much richer
in alkali metal than has been lueretofore treated, and to obtain hydrogen and
electricity at the same time.
I use as the outer enclosure of the apparatus a tank or cistern built up of
wrought or cast iron plates firmly riveted or bolted together to form a water fight
vessel. In the simplest form of the apparatus which I have designed, the approxi-
mate internal dimensions of the enclosure will be as follows: the height about
half the length and the breadth about one-sixth of the length. For instance,
in an enclosure of which the length is ten feet, I make the height five to six
feet and the breadth one foot nine inches to two feet, 1 do not, of course, bind
myself to these dimensions.
Referring to the drawings-
Figure is a transverse vertical section of a simple form of my denuder with
one cathode or range of cathodes;
Figure 2a similar view of a denuding apparatus showing 2 ranges of cathodes;
Figures and horizontal sections of the denuders shown in Figures 1 and 2
respectively.
:
Referring first to Figures 1 and 3, upon each of the sides of the wrought or
cast iron enclosure A. and running the entire length. I arrange a series of hori-
zontal shelves B of iron or other suitable material at a distance of a few inches
from each other. the uppermost shelf being about one foot from the top of the
enclosure and the lowest. three or four inches from the bottom. The shelves are
hollowed out on the upper surface to the depth of about one half inch, the de-
pression reaching to about one-quarter inch of the outer edges of the shelves.
At the alternate ends of each of adjacent shelves and about three inches from the
ends a narrow ridge C. one-eighth of an inch lower than the outer upper edge
of the shelf, runs across it and in the depression beyond the ridge, a hole D
about one inch in diameter is bored through the shelf. Holes E are also pro-
vided through each of the sides or ends of the enclosure at a short distance above
the level of the uppermost of the shelves B, and pipes E for the conveyance of
amalgam to the shelves are firmly fixed in the apertures. A hole G is also
provided in the bottom plate of the enclosure, and to this a pipe His firmly and
tightly fitted. This pipe serves for the withdrawal of the denuded mercury
from the enclosure. Pipes or tubes I are also provided for passing water into
the enclosure, and others for drawing off the solution of caustic alkali when
sufficiently concentrated. the feed pipe being fixed in the cover or in the side
near to the cover of the enclosure, and the run off pipe in the bottom of the
enclosure (when it must protrude one or two inches over the surface of the bottom
plate) or in the side near to the bottom. An orifice K in the cover of the
enclosure permits of the escape of the hydrogen gas liberated during the oxidation
of the alkali metal in the amalgam through pipe L.

page_text: I suspend, through apertures in the cover of the enclosure, in the central space
between the shelves, a series of plates or sheets of iron N which may be perforated
or in the form of grids, cast or bent so as to form hollow rectangular plates or
hoses, or use for this purpose sheets of stout iron gauze bent to shape as above
described. These hollow boxes, sheets or plates are of such depth that they
extend from about the level of the uppermost of the shelves B to within a short
distance from the bottom of the tank A and the suspenders Q must be carefully
insulated by insulators P where they pass through the metal cover of the tank.
These iron sheet or gauze boxes form the cathode element in relation to which the
amalgam upon the shelves is the anode and the arrangement constitutes a power-
ful voltaic battery. The suspenders Q have leading wires attached to them, and
a conducting wire T also leads from the tank casing and the anode trays B for
utilization of the electricity generated.
When the amalgam to be denuded is very rich in alkali metal, the material
of the superposed "horizontal shelves is preferably of stone, natural or artificial.
slate, glass or other similar non-conducting material, shaped and arranged as
before described. Or the upper series of shelves, over which the amalgam first
passes, may be of such non-conducting material and the lower ones of from. In
such cases, the sheets of flowing metal upon the shelves of non-conducting material
are metallically counceted with the iron outer casing of the enclosure.
1 extend the denuding capacity of the apparatus, if desired. exactly upon the
same principles as above described. The width of the enclosure is increased to
the requisite extent, and in addition to the two series of side shelves. I fix,
in the centre of the space between the side shelves, a third series of shelves C,
Figures 2 and 4. the breadth of each of which is the sum of the width of two
of the side shelves B. In this duplicate arrangement, two sets of cathode plates
are employed and are suspended in the spaces between ench of the series of side
shelves B and the central series of shelves C. It is evident that in the same way,
the power of the apparatus may be still further augmented.
In starting the manufacture of solution of caustic alkali by means of this
apparatus. the tank A is first filled with water or weak caustic solution to a
little over the level of the uppermost of the shelves B. The liquid amalgam is
then passed in and falling upon the uppermost shelf of each series, it fills the
depression and then falls through the opening at the further end to the next
shelf and so until all the shelves are charged, when, the stream being con-
tinued, it falls to and covers the bottom of the vessel, and the mercury is com-
pletely or almost completely denuded of alkali metal and allowed to flow out of
the vessel. When the solution of caustic alkali has attained a sufficiently high
degree of concentration, a tap Vattached to the outlet pipe is opened and the
liquor drawn off in a continuous stream, the supply of water being continued
through the inlet pipe so as to maintain a constant depth of liquor in the
vessel. The hydrogen gas liberated passes away by the aperture K through
pipe 1. provided for the purpose and is utilised either as fuel, for driving gas
engines, or otherwise. The electric current is led away by wires T, R attached
to the outer casing of the tank A and to the suspended cathodes N, to perform
any useful work.
In thus describing my invention. I would point out that it is not absolutely
essential that the tank or the cathodes should be of iron but it is essential that
the contents of all the trays shall be electrically connected with one wire and
the cathodes of any suitable metal with the other wire or conductor.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what
1 claim is:
1. The improvement in the manufacture of caustic alkali from an alkali metal
amalgum, which consists in causing the amalgam to travel in thin sheets over
a series of superposed horizontal shelves, arranged in a tank of water or caustic

page_text: solution, placing in juxtaposition thereto a metallic cathode or cathodes of iron
or other convenient metal. and connecting the thin sheets of amalgam with one
conductor, and the cathodes with another.
2. The apparatus for use in manufacturing caustic alkali from alkali metal
amalgams, substantially as herein described.
WM. P. THOMPSON & Co..
Patent Agents of Liverpool, Manchester, Birmingham and London.