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

page_text: Date of Application, 21st Aug., 1899-Accepted, 9th Dec., 1899
Improvements relating to the Manufacture of Caustic Alkali and
Halogen Gas and to 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 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 the manufacture of caustic alkali in accordance with my improve-
ment. Figure 2 is a transverse section of the same at the line 2-2 Figure 1,,
certain parts being omitted. Figure 3 is a transverse section of the same at
the line 3-3, Figure 1. Similar letters of reference designate corresponding
parts in all figures.
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,
magnesia. They rest upon a hearth which may be of iron or steel. A
cover a, closes the furnace and may be of fire clay. This cover rests upon the
walls a.
It has openings a through which pass anodes B, preferably made of
carbon. The electrical connections for these anodes may consist of metal rods
screwed into tapped holes formed in the upper ends of the anodes and conduct-
ing the current thereto from a source of electricity-for example, from a suit-
able dynamo with which the rods connect. The openings through which
the anodes pass are larger in diameter than the anodes. These openings are
closed around the anodes by auxiliary covers a Above the cover 2, and in
the masonry a of the furnace, a recess a is formed, and in this is a body of
salt C.
Below the hearth a¹, and communicating with the interior of the furnace A,
near one of the end walls of the latter is a conduit 1). Preferably this will
be cast integral with the hearth a. It extends to the lower portion of a
chamber E, and the latter may be part of a single casting comprising the con-
duit and the hearth. The lower portion of the chamber E communicates by
means of conduits F with that end of the interior of the furnace A which is
opposite the end whence extends the conduit D. It will be seen by reference
to Figure 3 that the conduits F are arranged one on each side of the conduit D.
A removable cover e closes the top of the chamber E, and the recess a
extends down to such cover.
A pipe H leads from the bottom of the chamber E, and is provided with
any suitable device for controlling the flow of its contents from it. As here
shown, a removable cap his employed for this purpose. This pipe may form
the negative terminal of the furnace.
G designates a steam pipe provided with a controlling cock g, and extending

page_text: into the conduit D) near that end which communicates with the furnace A.
Preferably the conduit will have a contraction near where the steam pipe
terminates, in order to produce an action analogous to that of an injector.
In the under side of the cover e of the chamber is a recess e¹. From the
recess e a pipe I, which may be made of iron or steel, extends downwardly to
the outside of the furnace. As here shown, it extends directly down through
the masonry. It communicates with a vessel J. From the top of the vessel J
a pipe K leads to a burner & with which also communicates an air pipe K¹ some-
what after the manner of an ordinary oxhydrogen blow pipe, but I utilize an
air blast to create a small suction for inducing a flow of hydrogen to the burner.
A cock controls the burner. This burner is comprised in a small auxiliary
melting furnace L formed in the masonry of the furnace A, and communicating
with the furnace A by means of a passage preferably inclined so that that
end which communicates with the main furnace A will always be submerged
in the contents of the latter. The molten salt in this auxiliary furnace will
normally be at the same level as the contents of the main furnace A. When-
ever the level rises in the auxiliary furnace there will be a flow into the main
furnace A. A pipe S extending from the top of the auxiliary furnace provides
for carrying away gaseous products of combustion.
A
Salt to be treated in the furnace, if supplied through a hopper or chamber M
and fed by a worm N into a pipe leading into the melting furnace L, may be
supplied to the electrolytic furnace in molten condition at a uniform rate.
pulley upon the shaft of the worm X derives motion from a belt a set in
motion by a suitable motor.
A plug T fitting a hole in the cover ², 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 inde-
pendent 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 ?.
It is intended that the body of salt C shall be maintained constantly in suffi-
cient quantity in the recess 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 open-
ings a, in quantity sufficient to fill the conduit I) and cover the hearth a, an
anode and its auxiliary cover being for this purpose temporarily removed.
Immediately afterwards the salt, c.g., sodium chloride, may be introduced in
a molten state in the same manner as the lead. Then the anode with its auxi-
liary cover will be replaced, and the full current turned on.
After the opera-
tion shall have been fully started, salt is supplied through the auxiliary fur-
nace L, entering the main furnace A in a molten state.
An alloy of sodium and lead will be formed. Steam under pressure escaping
from the pipe G will produce a rapid circulation through the conduit D to the
chamber E. It will be decomposed in transit 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 from the chamber E by the conduits F to the interior
of the main furnace A, where it will again act as a cathode, and take up sodium.
From the chamber E the hydrogen will escape through the pipe I into the
vessel J. Thence will also flow molten caustic soda. From the vessel J the
hydrogen will pass through the pipe K, to be consumed in the auxiliary fur-
nace L, where the salt is melted for maintaining the supply in the main fur-
uace A.
As already indicated, the contents of the furnace may at any time be removed
through the pipe H.
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page_text: Caustic alkali formed at the high temperature contemplated will be practi-
cally 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 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, introducing steam into the alloy, and burning the
resulting hydrogen for supplying heat for the operation, substantially as
specified.
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 a cathode, and thereby forming an alloy of
lead and the alkali metal, introducing steam into the alloy, and burning the
resulting hydrogen in contact with the salt required in the process and thereby
melting such salt, substantially as specified.
3. In an apparatus for the manufacture of molten caustic alkali, the combina-
tion of a main electrolytic furnace containing a molten electrolyte, an anode,
a molten metallic cathode, electrical connections for such electrodes, an auxi-
liary furnace, a conduit or chamber in fluid communication with the main elec-
trolytic furnace, means for introducing steam under pressure into the fluid
metallic contents of said conduit or chamber, and means for receiving hydrogen
obtained from the decomposition of the steam and for conducting it to the
auxiliary furnace for combustion.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.