IMPROVEMENTS IN THE TREATMENT OF BICARBONATE OF SODA OBTAINED IN THE AMMONIACAL PROCESS, AND IN MEANS AND APPARATUS FOR INCREASING THE DENSITY OF SODA AND RENDERING IT CAUSTIC."
Year: 1877

page_text: "
LETTERS PATENT to Ernest Solvay, of Brussels, in the Kingdom of Belgium;
Manufacturer, for the Invention of IMPROVEMENTS IN THE TREATMENT OF
BICARBONATE OF SODA OBTAINED IN THE AMMONIACAL PROCESS, AND IN MEANS
AND APPARATUS FOR INCREASING THE DENSITY OF SODA AND RENDERING IT
CAUSTIC."
Sealed the 4th December 1877, and dated the 12th July 1877.
PROVISIONAL SPECIFICATION left by the said Ernest Solvay at the Office
of the Commissioners of Patents on the 12th July 1877.
ERNEST SOLVAY, of Brussels, in the Kingdom of Belgium, Manufacturer.
." IM-
PROVEMENTS IN THE TREATMENT OF BICARBONATE OF SODA OBTAINED IN THE
AMMONIACAL PROCESS, AND IN MEANS AND APPARATUS FOR INCREASING THE
DENSITY, OF SODA AND RENDERING IT CAUSTIC."
The industrial preparation of soda, known also as carbonate of soda or soda salt;
gives a product which is more or less dense or more or less caustic, according to the
process of manufacture used. Thus, soda prepared by what is known as the
ammoniacal process, is generally light and completely carbonated.
For certain branches of manufacture, soda of great density is required, for others,
the soda should be more or less caustic. Now the object of my Invention is to com-
municate these properties to soda, and at the same time to improve the mode of
treating bicarbonate of soda obtained in the ammoniacal process, and it consists,
firstly, in the means and apparatus herein-after described for producing soda of con-
siderable density. To obtain a dense soda I simply melt away ordinary soda
completely on special apparatus; carbonic acid, ammonia, and vapour of water are
disengaged from the bicarbonate, and the carbonate then formed melts. The melted
soda is then run off and made into slabs, cakes, or other shapes, or it may be trans-
formed into grains of various sizes and shapes.
The apparatus in which the melting of the soda is effected consists of a retort or
melting pot made of iron, steel, or other suitable material capable of supporting
great heat and not subject to oxydation, from which it may be protected, if required,
ID..
71
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page_text: by a coating of enamel, clay, or other suitable materials, or the parts of the apparatus
in which the soda is melted may be made of silver, or be silvered over internally or
plated with platinum.
The said retort or melting pot which is open at top is set in a flue constructed
above a suitable furnace, an annular space being left between the outer surface of
the said melting pot and the inside of the said flue to allow of the products of com-
bustion from the furnace impinging upon and heating the said melting pot in their
passage to the chimney. In some cases I place round the bottom of the melting pot
a belt of fire-bricks a little distance one from the other so as to suitably distribute
the flames from the furnace, and thus obtain a regulated temperature in the upper
part of the apparatus. The bottom of the said melting pot, which is by preference
hemispherical or curved, communicates with the outside of the flue by means of a
suitable pipe, or by being formed so as itself to pass through the wall of
the flue and open outside of it by means of two apertures one above the other. To
the top of the melting pot is attached an annular concave pan forming the bottom
of a chest, to the top or cover of which chest is connected a funnel through which
the soda is introduced into the said chest and melting pot. The said chest cover is
also provided with a tube through which the gases and vapours disengaged from the
bicarbonate of soda by the action of heat escape and may be collected. In the said
chest is a rotatory vertical shaft upon which are projecting arms to which are jointed
scrapers which by the rotation of the said shaft prevent incrustations from adhering
to the bottom of the chest.
The action of the apparatus is as follows:-Bicarbonate of soda in a damp state
as it is produced in the manufactory is introduced into the apparatus either con-
tinuously or intermittently, but by preference continuously, through the funnel
herein-before described. When the said apparatus is nearly full, the concave bottom
of the chest contains bicarbonate of soda which is being decomposed by the action
of heat into carbonate of soda; and carbonic acid, ammonia, and steam are disengaged
from the said bicarbonate of soda, and pass off through the tube in the cover of the
chest, and may be collected for use. The carbonate of soda thus formed melts and
gradually sinks down in the melting pot, at the same time acquiring a high degree
of temperature, so that when it has reached the bottom of the melting pot it is
completely melted and liquid and is drawn out from one or other of the two apertures
herein-before described outside the apparatus. It is preferred to draw out the liquid
soda from the upper aperture, as any impurities then fall to the bottom, and may be
removed through the lower aperture.
.
The melted soda may be cooled rapidly in various ways, but I prefer to use for
the purpose a direct aspersion of water in small quantities upon the said melted soda;
by this means the water used evaporates speedily and none remains in the soda.
If it be required to have the soda in the form of powder it may be pulverised in
the usual way, or if it be required to obtain it in grains it may be run on to a metal
plate rotating with more or less velocity and upon which a small stream or drops of
water may be made to play in small quantities so as to rapidly evaporate.
Instead of the melting pot being constructed with a chest above it and mechanical
scrapers, as herein-before described, the melting pot may be constructed with a simple
cover provided with a funnel for the introduction of the soda, and a tube for the
outlet of the gases and vapours produced. A bell-shaped or conical guide may
in this case be set in the melting pot so as to prevent the soda descending in
the said melting pot from having too great a thickness, and thus not getting
thoroughly heated.
The arrangement of the said apparatus may vary according to circumstances;
and instead of the melting pots being cylindrical and set vertically, any other suitable
shape and arrangement may be adopted in carrying out my Invention.
My Invention consists, secondly, in means and apparatus for rendering soda
caustic, which I effect by injecting into melted carbonate of soda or soda salt a jet
of vapour of water, or by injecting water into it from the surface. The water or
steam forms with the melted soda a hydrate of soda and liberates the carbonic acid

page_text: it contained. When the soda has been rendered sufficiently caustic, the injection of
steam or water is stopped, and the caustic soda is run off' and made into slabs, cakes,
or other suitable shapes, or it may be granulated or reduced to powder.
The operation of rendering soda caustic may be effected in apparatus constructed
as herein-before described in reference to the process of increasing the density
of soda; the water or steam being injected into the melting pot through a suitable
pipe perforated with holes, and penetrating into the melting pot at that part
where the soda is completely liquid and melted; or the melting soda may be drawn
off from the apparatus into a vessel placed underneath it, and the water or steam
may be injected into it.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Ernest Solvay in the Great Seal Patent Office on the 5th January
1878.
ERNEST SOLVAY, of Brussels, in the Kingdom of Belgium, Manufacturer. "IM-
PROVEMENTS IN THE TREATMENT OF BICARBONATE OF SODA OBTAINED IN THE
AMMONIACAL PROCESS, AND IN MEANS AND APPARATUS FOR INCREASING THE
DENSITY OF SODA AND RENDERING IT CAUSTIC."
The industrial preparation of soda, known also as carbonate of soda or soda salt,
gives a product which is more or less dense or more or less caustic, according to the
process of manufacture used. Thus, soda prepared by what is known as the
ammoniacal process is generally light and completely carbonated.
For certain branches of manufacture, soda of great density is required, for others,
the soda should be more or less caustic. Now the object of my Invention is to
communicate these properties to soda, and at the same time to improve the mode of
treating bicarbonate of soda obtained in the ammoniacal process, and it consists,
firstly, in the means and apparatus herein-after described for producing soda of con-
siderable density. To obtain a dense soda I simply melt ordinary soda completely
in special apparatus, into which I introduce soda in the form of bicarbonate; carbonic
acid, ammonia, and vapour of water are disengaged from the bicarbonate, and the
carbonate then formed melts. The melted soda is then run off and made into slabs,
cakes, or other shapes, or it may be transformed into grains of various sizes and
shapes.
The apparatus in which the melting of the soda is effected consists of a retort or
melting pot made of iron, steel, or other suitable material capable of supporting great
heat and not subject to oxydation, from which it may be protected, if required,
by a coating of enamel, clay, or other suitable materials; or the parts of the
apparatus in which the soda is melted may be made of silver, or be silvered over
internally.
The said retort or melting pot which is open at top is set in a flue constructed
above a suitable furnace, an annular space being left between the outer surface of
the said melting pot, and the inside of the said flue to allow of the products of com-
bustion from the furnace impinging upon and heating the said melting pot in their
passage to the chimney. In some cases I place round the bottom of the melting
pot a belt of fire-bricks a little distance one from the other so as to suitably dis-

page_text: tribute the flames from the furnace and thus obtain a regulated temperature in the
upper part of the apparatus. The bottom of the said melting pot, which is by
preference hemispherical or curved, communicates with the outside of the flue by
means of a suitable pipe, or by being formed so as itself to pass through the wall of
the flue and open outside of it by means of two apertures one above the other. To
the top of the melting pot is attached an annular concave pan forming the bottom
of a chest, to the top or cover of which chest is connected a funnel through which
the soda is introduced into the said chest and melting pot. The said chest cover is
also provided with.a tube through which the gases and vapours disengaged from
the bicarbonate of soda by the action of heat escape and may be collected. In the said
chest is a rotatory vertical shaft upon which are projecting arms to which are jointed
scrapers which by the rotation of the said shaft prevent incrustations from adhering
to the bottom of the chest.
Instead of the melting pot being constructed with a chest above it and
mechanical scrapers, as herein-before described, the melting pot may be constructed,
with a simple cover provided with a funnel for the introduction of the soda, and a
tube for the outlet of the gases and vapours produced. A bell-shaped or conical
guide may in this case be set in the melting pot so as to prevent the soda descending
in the said melting pot from having too great a thickness, and thus not getting
thoroughly heated.
The arrangement of the said apparatus may vary according to circumstances; and
instead of the melting pots being cylindrical and set vertically, any other suitable
shape and arrangement may be adopted in carrying out my Invention.
My Invention consists, secondly, in means and apparatus for rendering soda caustic,
which I effect by injecting into melted carbonate of soda or soda salt a jet of vapour
of water, or by injecting water into it from the surface. The water or steam forms
with the melted soda a hydrate of soda, and liberates the carbonic acid it contained.
When the soda has been rendered sufficiently caustic, the injection of steam or
water is stopped and the caustic soda is run off and made into slabs, cakes, or other
suitable shapes, or it may be granulated or reduced to powder.
The operation of rendering soda caustic may be effected in apparatus constructed
as herein-before described in reference to the process of increasing the density of
soda, the water or steam being injected into the melting pot through a suitable
pipe perforated with holes, and penetrating into the melting pot at that part
where the soda is completely liquid and melted. Or the melted soda may be
drawn off from the apparatus into a vessel placed underneath it, and the water or
steam.may be injected into it.
Having thus described the nature of my said Invention I will proceed to describe
with reference to the accompanying Drawing the manner in which the same may be
performed. Fig. of the accompanying Drawing represents in transverse vertical
section an apparatus for the treatment of bicarbonate of soda obtained by the
ammonical process, so as to transform it at once into soda of considerable density.
G is a retort or melting pot, made of iron, steel, or other suitable material, or coated
with a material capable of supporting great heat and not subject to oxydation.
The said retort or melting pot G, which is open at the top, is set in a flue J con-
structed above a grate or furnace H, an annular space being left between the outer
surface of the said melting pot G and the walls of the said flue J to allow of the
products of combustion from the grate or furnace H impinging upon and heating
the said melting pot G in their passage to the chimney through the passages or
channels I and K. The bottom of the said melting pot G which is curved, com-
mmunicates with the outside of the flue J by being formed so as to pass through the
wall of the flue J, and to open outside of it by means of two apertures o, o², one
above the other. In the top of the said melting pot G is attached an annular
concave pan C, forming the bottom of a chest C¹, to the top or cover C³ of. which
is connected a funnel E through which the bicarbonate of soda is introduced into
the said chest C¹ and melting pot G. The cover C2 of the said chest C₁ is also
provided with a tube T, through which the gases and vapours disengaged from the
.
+

page_text: bicarbonate of soda by the action of the heat escape and may be collected. In the
said chest C is a rotatory vertical shaft A, supported and guided by a bracket D, the
ends of which are affixed to the sides of the chest C¹. The said rotatory shaft A
receives motion from bevilled gearing B, and upon its lower end are projecting
arms F, to which are jointed scrapers R, which by the rotation of the shaft A
prevent incrustations from adhering to the bottom Ċ of the chest C³.
The action of the said apparatus is as follows:-
:
Bicarbonate of soda in a damp state, as it is produced in the manufactory, is
introduced into the apparatus either continuously or intermittently, but by preference
continuously, through the funnel E. When the said apparatus is nearly full, the
concave bottom C of the chest C contains bicarbonate of soda, which, by the action
of heat from the furnace H, is being decomposed into carbonate of soda, and car-
bonic acid, ammonia, and steam are disengaged from the said bicarbonate of soda,
and pass off through the tube T in the cover C of the chest C', and may be
collected for use. The carbonate of soda thus formed melts and gradually sinks
down in the melting pot G, at the same time acquiring a high degree of temperature,
so that when it has reached the bottom of the melting pot G, it is completely.
melted and liquid, and is drawn out from one or other of the apertures o or o¹
outside the apparatus.
.It is preferred to draw out the liquid soda from the upper aperture o¹, as then
any impurities fall to the bottom and may be removed through the lower aperture o.
The melted soda may be cooled rapidly in various ways, but I prefer to use for the
purpose a direct aspersion of water in small quantities upon the said melted soda;.
by this means the water used evaporates speedily and none remains in the soda.
If it be required to have the soda in the form of powder it may be pulverized in;
the usual way; or if it be required to obtain it in grains, it may be run on to a
metal plate rotating with more or less velocity, and upon which a small stream or
drops of water may be made to play in small quantities so as to rapidly evaporate.
Fig. 2 is a transverse vertical section representing parts of apparatus constructed
according to another arrangement of my Invention. Fig. 3 is a horizontal section
of the same. G is the melting pot which differs from the melting pot G, Fig. 1, in
that the bottom is hemispherical and communicates with the outside of the flue J
by means of a pipe t. Round the bottom of the said melting pot G, Figs. 2 and 3,
is placed a belt of fire-bricks b, b, a little distance one from the other, so as to
distribute the flames from the furnace H, and thus obtain a regulated temperature
in the upper part of the apparatus. The upper parts of the apparatus, represented
in Figures 2 and 3, being similar to those represented in Figure 1, I have not
thought it necessary to shew them in Fig. 2.
Fig. 4 represents in vertical section a modification of the apparatus shewn in
Fig. 1. The melting pot G, in Fig. 4, instead of being provided in a chest and
mechanical scrapers above it, is constructed with a simple cover C, to which is affixed
a funnel E, for the introduction of the bicarbonate of soda, and a tube T for the
outlet of the gases and vapours produced. X is a bell-shaped or conical guide which
may be set in the melting pot G for the purpose of preventing the soda descending
in the said melting pot from having too great a thickness and not getting
thoroughly heated. H is the furnace, and t is a pipe leading from the bottom of
the melting pot to the outside J¹ of the flue J.
In using the apparatus represented in Fig. 4 the bicarbonate of soda is introduced
through the funnel E into the melting pot G, so as to completely fill the said melting
pot. The soda sinks down to the bottom of the melting pot in a melted state and
is drawn out through the pipe t.
In rendering soda caustic, according to my Invention, apparatus constructed as is
represented in Figs. 1, 2, 3, and 4 of the accompanying Drawings may be used,
though other arrangements of apparatus may be equally applicable in performing
my Invention.
When the apparatus represented in Fig. 1 is used for this purpose, the melting
pot G is provided with a suitable pipe P, the end of which pipe projects into the

page_text: lower part of the said melting pot, into which it opens by a series of perforations,
or small holes, through which water or steam is injected into the liquid melted soda
in the said melting pot. In this case the caustic soda is by preference drawn. out
through the upper aperture o¹.
When either of the apparatus represented in Figs. 2 or 4 is used in the process of
rendering soda caustic, the melted soda is drawn off from the melting pot G into
any suitable vessel placed underneath it, and water or steam is then injected into
the said melted soda.
Having thus described the nature of my said Invention and the manner in which
the same may be performed, I wish it to be understood that I do not confine myself
to the precise details herein-before described and illustrated in the accompanying
Drawings, as the same may be varied without departing from the nature of my
said Invention; but I claim as my said Invention,―
1st. The process herein-before described which consists of decomposing and
melting successively in closed apparatus, provided with tubes for the escape of the
gases and vapours evolved, bicarbonate of soda produced by the ammoniacal process,
so that the bicarbonate of soda introduced into the said apparatus issues therefrom
in a completely melted and liquid state, a carbonate of soda essentially, as herein-
before described.
2ly. The process herein-before described, of rendering more or less caustic
carbonate of soda manufactured by the ammoniacal process, by injecting water or
steam into a bath of melted soda, and more especially into liquid soda produced by
the process herein-before described under the first head of my Invention.
3ly. The combination and arrangement of parts of apparatus for decomposing
and melting successively and continuously bicarbonate of soda into carbonate of
soda, or soda salt, and for rendering carbonate of soda caustic essentially as herein-
before described and represented in the accompanying Drawings.
In witness whereof, I, the said Ernest Solvay, have hereunto set my hand
and seal, this Thirty-first day of December, in the year of our Lord
One thousand eight hundred and seventy-seven.
TONTANT SOLVE