Improvements in the Manufacture of Caustic Alkalies from Alloys of Lead with the Alkaline Metals.
Year: 1898

page_text: Date of Application, 28th June, 1898-Accepted, 15th Oct., 1898
Improvements in the Manufacture of Caustic Alkalies from Alloys of
Lead with the Alkaline Metals.
I, CHARLES ERNEST ACKER, of the City of East Orange, County of Essex, in
the State of New Jersey, United States of America, Chemical Engineer, do hereby
declare the nature of this invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
The object of my invention is to produce alkali metal hydrates from alloys of
the alkali metals and lead, to effect the conversion rapidly, and in inexpensive
apparatus, to obtain a pure and concentrated product without the necessity of
evaporating a solution containing it, and without confining under considerable
pressure the hydrogen evolved; and additionally to secure the resulting lead in a
clean, solid, metallic state, free from the alkaline metal, and ready for subsequent
use in the manufacture of new alloy without appreciable loss in remelting.
The essential features of the method as carried out by me consist in the treat-
ment of the alloy containing the alkaline metal, while molten, within specially
designed apparatus, by steam, in direct contact with the molten alloy; in effect-
ing the removal of the resulting hydrate from the point where it is formed, and in
precluding it from subsequent contact with the steam, thereby preventing it
from taking up or absorbing more than a trace or a very small percentage of
moisture; and in removing the hydrate as it is formed in order to enable the steam
to act upon the exposed alloy. Thus rapid decomposition of the steam will occur,
with the consequent rapid removal of the alkaline metal from the alloy, and rapid
formation of alkaline metal hydrate. The hydrogen formed is caused to escape
from the apparatus without danger, and without permitting ingress of atmo-
spheric air.
Apparatus suitable for use in carrying out this process is shown in vertical
section in the accompanying drawing.
The principal vessel C is shown as consisting of a cylindrical pot or cauldron
of cast iron having a deep lute or annular recess formed by double outside walls,
and mounted in suitable manner in a coal or gas furnace, whereby its contents
may be made molten. Suitable pipes for withdrawing its contents are shown
at L, M and N. A bell G which may be made of cast iron extends downward
into the pot C, and is supported with its lower edge at the desired distance from
the bottom of the pot by the pipe E, upon which may be mounted a hood, F,
the sides of which extend downward unto the lute. Resting on top of the pot C,
and secured thereto, is a shield D, open in the center except for two or more
strong ribs O, and a hub P, here shown as engaging and supporting the pipe E
with its attached castings G and F. A steam pipe I provided with gauge J
and regulating valve K is connected with the pipe E above the shield, and a
cap H serves to close the said pipe E when desired.
Preparatory to using the converter shown in the drawing it should be heated
sufficiently high to melt lead, and this temperature should thenceforth be main-

page_text: tained. A quantity of some material, as, for example, alkaline hydrate, which
is easily molten at this temperature, is then run into the lute until it rises above
the lower edge of the hood sufficiently high to form an effective seal.
The correct quantity of alkali metal alloy will be introduced, preferably in
molten condition, through the pipe E, the alloy rising inside and outside of
the bell, G. After the pipe is closed by the cap H, steam in small quantity is
turned on by slightly opening the valve K. The immediate effect of this will
be to depress the alloy in the pipe and bell. Steam will be decomposed, hydrogen
liberated and alkaline hydrate formed. The level of the alloy will be depressed
to the lower edge a of the bell, as shown, where both the hydrogen gas and the
molten alkaline hydrate will escape by rising through the alloy outside of the
bell, where the alkaline hydrate remains. It is necessary to exclude atmos-
pheric air from contact with the alkaline hydrate thus resting on the outer
surface of the alloy, for the reason that, if present, oxygen would be absorbed
by the hydrate which would then act as a carrier thereof from the air to the alloy,
in which case both the lead and the alkali metal would be oxidized and impurities
introduced into the hydrate. The hydrogen gas which accumulates very rapidly,
must be permitted to escape with great freedom to the exterior. This double
object is attained by the employment of a liquid seal in the lute, as described.
The accumulation of hydrogen gas outside of the bell immediately depresses
the molten caustic alkali on the inside of the seal in the lute until it reaches
the bottom edge of the seal, when the hydrogen will escape by bubbling up
through the fluid material. The operation having been thus fairly started, the
valve K will be still further opened to admit steam at the working rate.
the level of the alloy below the bell may be as indicated by a, the level of the
alloy outside of the bell by e and the level of the alkaline hydrate within the pot
or cauldron by d. The hydrogen gas will depress the alkaline hydrate in the
space 6 between the pot or cauldron and the hood to a point below the lower
edge of the hood and force it up in the lute outside of the hood to a level, as,
for example, the one indicated by c.
Then
The capacity of the converter for rapid extraction of the alkali metal from a
given quantity of the alloy is largely determined by the area of the alloy sur-
face a, and the area of the outer channel of the lute, through which the hydrogen
escapes. In order that the steam may act directly on the alloy it is necessary
that, as its bulk diminishes and until it finally becomes pure lead, the mouth of
the bell should always be sealed by the metal. An appropriate charge of alloy,
therefore, is such that the resulting lead will seal the bell. When a sample of
the contents of the lower part of the converter secured through the pipe N,
shows that the lead is soft, the operation will be finished, and the products are
run off through the pipe N.
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 I
claim is :-
1. The process of making caustic alkali which consists in submitting a fused
alloy containing an alkali metal to the direct action of steam, whereby the steam
is decomposed and hydrogen gas and an alkaline hydrate are formed; and in
immediately removing the hydrate thus formed whereby the steam is again per-
mitted to come into direct contact with the alloy.
2. The herein described process which consists essentially in treating molten
alloys of the alkali metals by the direct application of steam in such manner as
to directly produce the alkali-metal hydrate; and in immediate removal of the
hydrate from direct contact with the steam.
3. The process of making caustic alkali consisting in continuously submitting
a fused alloy containing an alkali metal to the direct action of steam, thus form-
ing hydrogen gas and an alkaline hydrate, and in continuously removing the
hydrate thus formed.

page_text: 4. In a converter for use in making caustic alkali the combination with a
pot or receptacle mounted in a furnace of a bell extending down into the re-
ceptacle, means for supplying steam to said bell, and means for permitting
escape of hydrogen resulting from the decomposition of steam.
5. In a converter, for use in making caustic alkali, the combination with a
pot or receptacle of a bell, extending down into the same, means for supplying
steam to said bell, and a liquid sealed joint through which may escape hydrogen
resulting from the decomposition of steam without permitting ingress of air.
Dated this 28th day of June 1898.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.