Improvements in the Manufacture of Caustic Alkali and Halogen Gas and Apparatus therefor.
Year: 1899

page_text: Date of Application, 21st Aug., 1899-Accepted, 9th Dec., 1899
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Caustic Alkali and Halogen Gas
and Apparatus therefor.
I, CHARLES ERNEST ACKER, of 424, Pine Avenue, Niagara Falls, Niagara County,
New York, United States of America, 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:―
The object of my invention is to economize in the electrolytic production of
practically anhydrous caustic alkali and halogen gas. My invention consists in a
novel process and also in an improved apparatus for the purpose.
In the accompanying drawing, Figure 1 is a longitudinal vertical section of an
apparatus for manufacturing caustic alkali in accordance with my invention.
Figure 2 is a vertical section of certain parts upon an enlarged scale. Figure 3
is a top view of those parts upon the same scale. Figure 4 is a perspective view
of a portion of the cover a2 and shewing one of the anodes B. Figure 5 is a plan
view of the parts shown in Figure 4. Similar letters of reference designate
corresponding parts in all figures.
A
A designates an electrolytic furnace which may be of any suitable form. As
here shown it has walls, a, which may be made of basic material, as, for example,
amagnesia. They rest upon a hearth, a¹, which may be of iron or steel.
cover, a², closes the furnace and may be of fire-clay. This cover rests upon the
walls, a. It has openings, a³, through which pass anodes, B, preferably inade of
carbon.
The electrical connections for these anodes may consist of metal rods provided
at their extremities with integral metal caps, whose rims are caused to closely
embrace the upper ends of the anodes so as to be firmly united thereto. These
rods conduct the current to the anodes from a source of electricity,-for example,
from a suitable dynamo. The openings a³, are larger in diameter than the anodes.
These openings a³ are closed by ring-shaped covers a¹0, each made in two semi-
circular parts so that they may be applied sidewise, and of such size that when applied
they will snugly fit around the anodes immediately above the cover a², as shown
more particularly in Figures 4 and 5. Above the cover a², and in the masonry, a³,
of the furnace, a recess, a, is formed, and in this is a body of salt C.
Below the hearth, a', and communicating with the interior of the furnace, A,
near one of the end walls of the latter, is a conduit, D. Preferably this will be
cast integral with the hearth, a¹. It extends to a well, D¹, at that end which is
farthest away from its communication with the furnace, A. It will be observed
that the bottom of the conduit, D, is inclined towards the well, or, in other words,
it is arranged at an angle. It will also be noticed that the well is at a lower
level. A pipe, H, communicates with the bottom of the well, and may form the
negative terminal.
Above the well is a chamber, E, which is closed by a removable cover, e, and.
communicates by a conduit, F, with the interior of the furnace at the opposite

page_text: end from that where the furnace is in communication with the conduit, D. Through
a diaphragm forming the bottom of the chamber and the top of the well, D,
vertically extends a conduit, Q, which is open at both ends. This diaphragm is
shown as made of a removable prece, and may be made of iron or steel.
A steam pipe, G, having a controlling cock, g, and preferably made of iron or
steel, extends downwardly through the cover or the chamber, E, and
thence through the conduit, Q, nearly to the bottom of the latter.
This con-
duit, Q, may be made of iron or steel. At the lower end of the steam pipe is
a distributor, R, which, as here shown, consists of a cap secured by means of a
screw thread to the lower end of the steam pipe, so that there will be a space
between its bottom and the lower end of the steam pipe. In this cap are a number
of passages, r, which communicate with its interior below the steam pipe, and
extend through the upper end of the cap. Steam passing down through the steam
pipe will escape through the passages, r, in an upward direction, oxidizing the
sodium within the conduit, Q, and inducing circulation upwardly therein. Cir-
culation will also occur from the furnace, A, into the upper end of the conduit, D,
thence down into the well, D, thence into the lower end of the conduit, Q, and
from the upper end of the latter into the chamber, E, and into furnace, A.
A plug, T, fitting a hole in the cover, a², and provided with a handle extending
above the body of salt, C, may be manipulated for the purpose of permitting some
of the body of salt, C, to flow into the main furnace, A. Thus an independent
feed will be possible.
From the upper part of the interior of the furnace, A, a channel, P, extends
through the masonry, and communicates with a pipe, p.
It is intended that the body of salt, C, shall be maintained constantly in
sufficient quantity in the recess, w, to form a seal for the openings to the
covers, a² and e.
Lead in a molten state may be introduced through one of the anode openings, a³,
in quantity sufficient to fill the conduit, D, and cover the hearth, a', an anode
being for this purpose temporarily removed. Immediately afterwards the salt,
e.g., sodium chloride, may be introduced in a molten state in the same manner as
the lead. Then the anode will be replaced, and the full current turned on.
the operation shall have been fully started, salt will be supplied in any suitable
manner to the furnace.
After
The effect of the passage of the current through the molten salt from the
anodes to the cathode, is to decompose the salt, chlorine gas being liberated at
the anodes and passing up through the molten salt, and metallic sodium being
liberated on the surface of the cathode with which it forms an alloy. The sodium
diffuses to a certain extent throughout the mass of lead contained in the furnace.
Steam under pressure escaping from the pipe G will produce a rapid circulation
through the conduit D to the well D₁ and chamber E. During transit it will
be decomposed within the conduit by the sodium in the alloy, and caustic soda
and hydrogen will result.
Through the conduit D, flow, to the chamber E, caustic soda, impoverished
alloy, and hydrogen. In the chamber E a separation occurs. Impoverished alloy
or lead will return by the chamber E and the conduits F, to the interior fur-
nace A, where it will again act as a cathode and take up sodium.
The
The contents of the furnace A are to be maintained molten and fluid.
temperature necessary to secure this condition will preferably be maintained by
employing a suitable electric current density on the anodes and cathode with a
higher electromotive force than would ordinarily be required to decompose the
molten salt. In other words, if reliance is placed upon the current to make up
the loss of heat due to radiation and conduction, the electrical energy will have
to be in excess of that needed for the decomposition of the molten salt only. The
heat resulting from the combination of the sodium with the oxygen of the steam
will compensate to a considerable extent for the loss of temperature incident to
radiation and conduction. This is possible because of causing the oxydation of

page_text: sodium in close proximity to the molten electrolyte, and causing the impoverished
alloy or lead at the somewhat higher temperature resulting from the chemical com-
bination of the alkali metal with the oxygen of the steam, to immediately return
and come in contact with, or proximity to, the molten electrolyte so as to impart
some of the heat thereto, thus reducing the amount of electrical energy required
to be converted into heat energy to maintain the electrolyte in the molten state,
and making possible the operation of the furnace at a lower voltage and at a
higher efficiency than would otherwise be the case.
Hydrogen and caustic soda pass through a pipe, I, which communicates with
pipes, 1, 1. The caustic soda flows through the pipe, 14, into a drum, U, and
the hydrogen passes off into any suitable receiver, or it may be permitted to
escape into the air.
Chlorine gas will pass off through the channel P' and pipe p. The contents of
the furnace may be removed at any time through the pipe H.
This apparatus affords easy access to parts sometimes requiring inspection, for
inspection may be had by removing the body of salt; and then taking off the cover
of the chamber, E.
Caustic alkali formed at the high temperature contemplated will be practically
anhydrous.
It will be understood that the decomposition of the steam, and the formation of
caustic soda and hydrogen will occur in transit.
I do not wish to be confined to producing caustic soda and chlorine by my
invention, as I may employ the invention for the production of some other caustic
alkali and gas.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
-
1. In the manufacture of fused caustic alkali, the process which consists in
electrolytically decomposing, in a suitable furnace, a molten salt of an alkali metal
while resting on a body of molten lead, constituting the cathode, and thereby
forming an alloy of lead and the alkali metal, causing a movement of the cathode
metal and resulting alloy into and through a communicating conduit, and intro-
ducing steam into said conduit and thereby oxidizing the alkali metal contained
in the molten alloy in transit within said conduit, and so forming fused caustic
alkali.
2. In the manufacture of fused caustic alkali, the process which consists in
electrolytically decomposing a molten salt of an alkali metal while resting upon a
body of molten lead constituting the cathode, and thereby forming an alloy of
lead and the alkali metal, and introducing steam under pressure into a receiving
conduit to cause a movement of the cathode metal and resulting alloy past an
anode or anodes into and through said conduit, and oxidizing the alkali metal in
transit, substantially as specified.
3. In the manufacture of fused caustic alkali, the process which consists in
electrolytically decomposing a molten salt of an alkali metal while resting upon
a body of molten lead constituting the cathode, and thereby forming an alloy of
lead and the alkali metal, and introducing steam under pressure into a separate
body of the alloy in fluid communication with the cathode to give a movement
sufficient to cause the return of the lead or impoverished alloy to a point where
it will again take up alkali metal, substantially as specified.
4. In the manufacture of fused caustic alkali, the process which consists in
electrolytically decomposing in a suitable furnace a molten salt of an alkali metal
while resting upon a body of molten lead constituting the cathode, and thereby
'forming an alloy of lead and the alkali metal, causing circulation of the cathode
metal and resulting alloy past an anode or anodes into a conduit communicating
with a chamber which also communicates with the furnace, introducing steam
into the conduit and simultaneously causing a circulation of the contents of the

page_text: conduit to the chamber where the molten alkali, the hydrogen and the lead or
impoverished alloy separate, removing the molten alkali and the hydrogen from
said chamber, and returning the metal to the furnace by the head attained in
the chamber, substantially as specified.
5. In the manufacture of fused caustic alkali, the process which consists in
electrolytically decomposing in a suitable furnace a molten salt of an alkali metal
while resting on a body of molten lead constituting the cathode, and thereby
forming an alloy of lead and the alkali metal, utilizing the heat of combination of
the alkali metal with oxygen to conserve the heat energy of the process by inject-
ing a proper quantity of steam under pressure through a separate body of the
alloy in fluid communication with the cathode metal, and returning the resultant
lead or impoverished alloy at a higher temperature to the point where it again
takes up the alkali metal.
6. In the manufacture of fused caustic alkali, the process which consists in
electrolytically decomposing in a suitable furnace, a molten salt of an alkali
metal while resting on a body of molten lead constituting the cathode, and thereby
forming an alloy of lead and the alkali metal, utilizing the heat of combination
of alkali metal with oxygen to conserve the heat energy by injecting a proper
quantity of steam under pressure through a separate body of the alloy in fluid
communication with the cathode metal and in close proximity thereto, whereby
the additional heat created will be directly conducted to the furnace.
7. In an apparatus for the manufacture of molten caustic alkali, the combination
of a furnace containing a molten electrolyte, an anode, a molten metallic cathode,
electrical connections for such electrodes, a conduit communicating with said
furnace, and means for supplying steam under pressure so as to effect circulation
through the furnace and conduit, substantially as specified.
8. In an apparatus for the manufacture of molten caustic alkali, the combination
of a furnace containing a molten electrolyte, an anode, a molten metallic cathode,
electrical connections for such electrodes, a conduit communicating with said
furnace, a chamber communicating with the chamber, and the furnace, and means
for supplying steam under pressure so as to effect circulation through said parts,
substantially as specified.
9. In an apparatus for the manufacture of molten caustic alkali, the combination
of a furnace containing a molten electrolyte, an anode, a molten metallic cathode,
electrical connections for said electrodes laterally extending conduits communi-
cating with different sides of said furnace, an upright conduit open at the ends
and communicating at its different ends with the two laterally extending conduits,
a steam outlet arranged in said upright conduit, and so constructed as to effect
upward circulation through said upright conduit and circulation through the fur-
nace and through the laterally extending conduits.
10. In an apparatus for the manufacture of molten caustic alkali, the com-
bination of a furnace containing a molten electrolyte, an anode, a molten metallic
cathode, electrical connections for such electrodes, a conduit communicating with
said furnace a chamber communicating with the conduit, a pipe extending down-
wardly from said chamber, and means for supplying steam under pressure so as to
effect circulation, substantially as specified.
11. The combination with an apparatus for the manufacture of molten caustic
alkali comprising a furnace containing a molten electrolyte, an anode, or a con-
ductor leading to the anode passing through an opening in the top of the furnace,
a molten metallic cathode and electrical connections for such electrodes, of a cover
in one or more parts surrounding the anode or its conductor and partly closing
said opening, and a body of salt resting upon said cover so as to more completely
close said opening, substantially as specified.
12. The combination with an apparatus for the manufacture of molten caustic
alkali comprising a furnace containing a molten electrolyte, an anode or a con-
ductor leading to the anode, a molten metallic cathode, and electrical connections.
for such electrodes of a main cover for said apparatus provided with an opening

page_text: through which passes the anode or its conductor, an auxiliary cover in one or more
parts surrounding the anode or its conductor and partly closing said opening, and
a body of salt resting upon said main cover and also upon said auxiliary cover
so as to more completely close said opening, substantially as specified.
Dotad this 21st day of August 1899
HASELTINE, LAKE, & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.