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
QUALI LEIE SETULFICATION.
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 electrolytically. My invention con-
sists in a novel process and also in an improved apparatus for the purpose.
The accompanying drawing is a longitudinal vertical section of an apparatus
for the manufacture of caustic alkali in accordance with my improvement.
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. These walls rest upon a hearth which may be of iron or steel.
The furnace is closed by a main cover a which may be made of fire clay. This
cover rests upon the walls a. In the cover are openings a through which pass
anodes B, preferably made 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
with which said rods connect. The openings a are larger in diameter than the
anodes. These openings are closed around the anodes by auxiliary covers a*
in the form of rings. Above the cover a, and in the masonry as 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 side walls of the latter is a conduit D. Preferably this will be
cast integral with the hearth a¹. It extends to the lower portion of a chamber E,
and the latter may be a portion of a single casting comprising the conduit and the
hearth.
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 h is employed for this purpose. This pipe may form the nega-
tive terminal of the furnace.
From the hearth a' is an extension a forming the bottom of the chamber E.
It will be seen that it is lower than the bottom of the furnace A. A conduit F
establishes communication between the lower ends of the furnace A and cham-
ber E.
Below the chamber E is a well E¹ to which extends the conduit D from the
furnace A. It will be observed that this well E' is lower than the conduit D).
From the upper portion of the chamber E a pipe I extends. As shown, it
is approximately horizontal-but preferably will have a slight decline towards
its outer end. The pipe I may advantageously be connected with an orifice O
formed in the upright wall of the chamber E in such a manner as to be lower
at the inner surface of the wall than at the outer surface. Caustic alkali col-
5D 077

page_text: lected in the chamber E is intended to escape through the pipe I, and by the
construction of the orifice O the latter forms a seal to prevent the escape of
hydrogen which will rise to the top of said chamber. A removable cap I may
close the outer extremity of the pipe I to facilitate the removal of obstructions.
A branch pipe I extends from the pipe I into a drum U:
Q designates a conduit of tubular form, open at both ends, and arranged
vertically within the chamber E and well E, at such a height as to be out of
contact with the bottom of the well E¹, and also out of contact with the top or
cover of the chamber E. As here shown, this conduit is provided with a cir-
cumferential rib that rests upon the bottom of the chamber, E.
R designates a circulator, here shown as made in the form of a screw or worm
and arranged in the lower portion of the conduit Q. It is fixed to a shaft R¹,
and the latter is provided with a step-bearing, upon the top of a tube 2 which
is shown as screwed into the cover e of the chamber E. Any suitable means
may be employed for rotating the shaft R for the purpose of actuating the
circulator. The direction of the rotation of the shaft R is to be such as to
cause the circulator to produce an upward circulation in the conduit Q.
G1, G2 designate steam pipes provided with controlling cocks g and extending
downwardly through the cover of the chamber E, and thence transversely into
the conduit Q intermediate of the extremities of said conduit.
The steam pipe G¹ is shown as extending in an approximately horizontal
direction into the conduit Q so that steam issuing therefrom will not have an
important, if any, effect in promoting circulation through the conduit Q. The
steam pipe G is, however, caused to enter the conduit Q at an upward incline
so that the steam emitted from it will contribute to cause an upward circula-
tion through the conduit Q.
Lead in a molten state may be introduced through one of the openings, a³
in the cover of the main furnace A, through which the anodes B pass, and in
quantities sufficient to fill the conduit D and cover the hearth a. One of the
anodes will, of course, have to be temporarily removed for this purpose. Im-
mediately afterwards the salt employed, for example, sodium chloride, may be
introduced in a molten state. Then the removed anode will be replaced and
the full current turned on.
Through the conduit Q flow to the chamber E, caustic soda, impoverished
alloy and hydrogen. In the chamber E a separation will occur. Impoverished
alloy or lead will return by the conduit F to the main furnace, where it will
again act as a cathode and take up sodium.
Hydrogen passes from the upper portion of the chamber E through a pipe V
into a pipe K, whence it ascends to a chamber into which also leads an air
pipe K, the latter being controlled by a valve terminating within the cham-
ber in a nozzle . The mixture of gases burns in an auxiliary furnace L
into which the salt, which is to be decomposed in the main furnace A, is fed,
through an opening of under control of a removable cover T. A body of salt
is maintained in a hopper M above the auxiliary furnace. If desirable, any
automatic or positive feed may be used instead of or in addition to the opening o
with its removable cover T. Products of combustion may escape from the
furnace through a conduit S.
After the operation shall have been fully started in the main furnace A, salt
may be supplied in a molten state from the auxiliary furnace through a con-
duit into the lower portion of the main furnace A.
The contents of the well E' may be at any time removed through the pipe H.
Chlorine gas will escape through the conduit P and pipe p.
The contents of the furnace A are to be maintained molten and fluid. The
temperature necessary to secure this condition will preferably be maintained by
a suitable electric current density on the anode or anodes and cathode with a
higher electro-motive force than would ordinarily be required to decompose
the molten salt.

page_text: It will be seen that there will be a circulation continuously in the same direc-
tion through an endless circuit, comprising two branches, one of said branches
being the hearth of the main furnace A containing that part of the molten metal
in contact with the electrolyte, and the other the conduit D and its connections;
also that steam is introduced into the circulation so that alkali metal will be
oxidized during transit, and also that such circuit or circulation is past one or
more anodes,
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 apparatus having two branches, a
molten salt of an alkali metal while resting on a body of molten lead constitut-
ing the cathode, thereby forming an alloy of lead and the alkali metal, and
causing a movement of the cathode metal and resulting alloy through said
apparatus and past an anode or anodes in one of the branches by means of a
mechanical circulator, and by introducing steam into the mass of the moving
molten alloy in the other branch to enter into the circulation.
2. In the manufacture of fused caustic alkali, the process which consists in
electrolytically decomposing in a suitable apparatus having two branches, a
molten salt of an alkali metal while resting on a body of molten lead constitut-
ing the cathode, thereby forming an alloy of lead and the alkali metal, and
causing a movement of the cathode metal and resulting alloy through said
apparatus and past an anode or anodes in one of the branches, by means of a
mechanical circulator, and by introducing a properly directed current of steam
into the moving body of molten alloy in the other branch to promote the
desired circulation.
3. 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 said electrodes, a conduit communicating
with said furnace, a mechanical circulator for effecting circulation through the
furnace and conduits, and means for supplying steam under pressure into the
mass of the cathode metal.
4. In an apparatus for the manufacture of molten caustic alkali, the combina-
tion of a furnace containing a molten electrolyte, an anode, a molten metallic
cathode, electrical connections for said electrodes, a conduit communicating
with said furnace, a mechanical circulator for effecting circulation through the
furnace and conduits, means for supplying steam under pressure into the mass
of the cathode metal, and emitting it in such a direction as to promote the
desired circulation.
5. In an apparatus for the manufacture of molten caustic alkali, the combina-
tion of a furnace containing a molten electrolyte, an anode, a molten metallic
cathode, electrical connections for said electrodes, laterally extending conduits
communicating with different sides of said furnace, an upright conduit open at
both ends and communicating at its different ends with the two laterally extend-
ing conduits, a mechanical circulator arranged in said upright conduit for effect-
ing circulation through the furnace and through the laterally extending con-
duits, and means for supplying steam under pressure into the mass of cathode
metal.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.