Improvements relating to the Manufacture of Sodium Bicarbonate, and to Apparatus therefor.
Year: 1894

page_text: Date of Application, 22nd May, 1894
Complete Specification Left, 19th Feb., 1895-Accepted, 9th Mar., 1895
PROVISIONAL SPECIFICATION.
Improvements relating to the Manufacture of Sodium Bicarbonate,
and to Apparatus therefor.
I, THOMAS CRANEY, Manufacturer, of 624 Harrison Street, Bay City,
Michigan, United States of America, do hereby declare the nature of this
invention to be as follows:-
:-
This invention relates to the commercial manufacture of bicarbonate of soda from
salt brine and the invention consists in the continuous process of manufacturing it.
by the electrolysis of salt brine.
The invention also relates to the apparatus or plant used for the process
whereby the article is produced in commercial form, all as more fully hereinafter
described.
I arrange a suitable number of electrolytic vats, such as has been used by me
heretofore for the continuous production of caustic soda in solution by the
electrolysis of salt brine.
The vats comprise a metallic tank, a diaphragm dividing the tank into two
compartments, a metallic frame supporting the diaphragm and forming the cathode,
a layer of carbon forming the anode, and a series of carbon pencils enclosed in
suitable supports and forming the electric connection with the anode, feed and
discharge connections of the lower chamber and feed and discharge connections of
the upper chamber.
A number of these tanks being arranged in vertical series, connections are made
between the like upper and lower chambers whereby the said chambers are
connected in series to overflow from one tank into the next one below and so on
through the entire series.
The apparatus also comprises a receiver into which the product from the lower
compartment of the last electrolytic vat discharges; I also provide a vertical
stand-pipe constituting a carbonator; a vertical branch communicating with the
lower end of the stand pipe, a pump: a supply pipe connecting the pump with the
receiver, a discharge pipe from the pump communicating into the upper end of
the stand-pipe and controlled by a valve; an overflow pipe from the vertical
branch into the soda chamber of the upper electrolytic vat, a receiver communi-
cating with the lower end of the stand-pipe through a valve controlled connection ;.
a centrifugal separator; a valve controlled discharge connection from the receiver
into the centrifugal separator; a discharge trunk from the centrifugal separator
for the solid products; a liquid discharge pipe from the centrifugal separator into
the receiver, a tank provided with a valve controlled discharge pipe into the
centrifugal separator; a conveyor; a drier; a grinding mill, a hot blast apparatus
a gas pump; a discharge pipe from the pump entering the top of the stand-pipe
and extending down inside, near the bottom of the same, and a supply pipe of the
pump connecting it with a suitable source of carbonic acid gas.
In practice, the parts being arranged as described they are intended to operate
as follows:
Salt brine from a suitable source is fed into the anode chamber of the upper
electrolytic vat, in quantity to produce a constant overflow and circulation into the
corresponding chamber of the next lower vat and so on through the whole series,

page_text: escaping from the last vat to be further treated as a by-product in any desired
manner, not forming a part of this invention.
The cathode or soda compartments of the electrolytic vats, we will suppose for
the present to be filled with pure water, also the receiver, stand-pipe and its
branch..
In establishing now the electrolytic action-it will be seen that the fresh water in
the cathode compartments of the electrolytic vats will become impregnated with
the caustic soda, and if we now set the pump to work, the contents of one chamber
will gradually overflow into the one next below and so on through the entire series,
into the receiver.
The pump being now in continuous operation, the solution of caustic soda will be
gradually delivered through the pipe into the top of the stand-pipe and from there
by displacement into the leg and through a pipe back into the cathode chamber of
the uppermost vat, thus forming a complete circulation of the liquid through the
cathode chambers, stand-pipe and branch.
The pump being set in operation and connected with a suitable source of supply
of carbonic acid gas (which may be produced in the usual manner by combustion
of carbon) the gas is injected through the pipe into the stand-pipe from which it
escapes near the bottom of the stand pipe and passes up through the liquid, its
quantity being sufficient to convert all the caustic soda contained therein into
bi-carbonate.
Should the concentration of the solution be sufficient to form a precipitate
bi-carbonate of soda it would fall to the bottom of the stand-pipe, while the
bi-carbonate in solution would find its way up through the branch and discharge
pipe back into the electrolytic vats. Here coming in contact and mingling with
the caustic soda produced therein it would be transformed into mono-carbonate of
soda and pass as such into the receiver, from which it would be again delivered
into the stand-pipe and subjected to the repeated process of carbonation. In the
continuous operation of the apparatus we would have thus a constant supply of
mono-carbonate of soda into the stand-pipe and converted therein by the constant
supply of fresh carbonic acid gas into bi-carbonate of soda, and all the bi-carbonate
which remains in solution is constantly returned into the cathode chambers of the
electrolytic vats and re-converted into mono-carbonate by the additional supply of
caustic soda.
The precipitate of bi-carbonate of soda will collect in the bottom of the stand-
pipe, or if the valve is dispensed with or left open it will collect into the receiver
and from there it may be discharged at suitable intervals into the centrifugal
separator.
This separator is intended to operate in the usual manner to remove the liquid
from the solid matter, the liquid being returned through the pipe into the
receiver.
The precipitate of bi-carbonate is discharged and transferred by the conveyor
into the drying apparatus, which may be of any suitable description, the. drying
being preferably effected therein by passing through it a mixture of hot air and
carbonic acid gas from the apparatus, the material being received in a suitably
dried condition is discharged into a suitable grinding mill from which it leaves as a
commercial product.
My invention is not limited to the use of any particular electrolytic vat, however,
I prefer to use an electrolytic vat in which an effective separation is obtained by a
diaphragm, between an anode and cathode chamber. Should, however, any traces
of salt find its way into the product of the cathode chambers and from there into
the bi-carbonate of soda, it may be removed by treating it in a centrifugal separator
by the use of a suitable washing fluid, such as a solution of bi-carbonate of soda
introduced from the tank.
It will further be seen that in my construction of apparatus, the bi-carbonate of
soda is precipitated in a medium or body of a solution of bi-carbonate of soda, owing
to making the stand pipe of great height and capacity relatively to the amount of

page_text: bi-carbonate produced and by introducing the carbonic acid gas near the bottom
and the mono-carbonate near the top, whereby the latter is entirely converted into
bi-carbonate before it reaches the bottom.
By using a suitable number of electrolytic vats and supplying the same with a
continued and ample supply of salt brine, and by a proportionate supply of fresh
water into the cathode compartment to replace the loss by decomposition and
evaporation my apparatus will work on the continuous plan.
It will be understood that by charging the apparatus at the start with a solution
of mono-carbonate or bi-carbonate of soda, the time for obtaining its normal
operation is correspondingly shortened.
My invention includes a distinct sub-process of making mono-carbonate of soda,
by charging the cathode chambers with a solution of bi-carbonate. This is an
important advantage as it reduces the electrical horse power required to electrolize
the salt to a minimum on account of the chemical affinity of the bi-carbonate and
the caustic soda.
Dated this 22nd day of May 1894.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
Improvements relating to the Manufacture of Sodium Bicarbonate,
and to Apparatus therefor.
1, THOMAS CRANEY, of 624 Harrison Street, Bay City, Michigan, United
States of America, Manufacturer, 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 :-
This invention relates to the commercial manufacture of bicarbonate of soda from
salt brine and the invention cousists in the continuous process of manufacturing it
by the electrolysis of salt brine.
"
The invention also consists in the apparatus or plant used for the process whereby
the article is produced in commercial form, all as more fully hereinafter described.
In the accompanying drawing,
Figure 1 is a diagrammatic view of the plant, and
Figure 2 is a vertical section of one of the electrolytic vats.
A A A A represent a suitable number of electrolytic vats, such as has been
used by me heretofore for the continuous production of caustic soda in solution by
the electrolysis of salt brine.
In the section shown in Figure 2, the details of construction of one of such vats
is shown in which B represents a metallic tank, C a diaphragm dividing the tank
into two compartments D and E. F is a metallic frame supporting the diaphragm
and forming the cathode, G represents a layer of carbon. forming the anode,
and H a series of carbon pencils enclosed in suitable supports and forming the
electric connection with the anode, I and I' are the feed and discharge connections
of the chamber E and J J the feed and discharge connections of the chamber D.
A number of these tanks being arranged in vertical series, connections are made
between the like chambers D and E whereby the said chambers are connected in
series to overflow from one tank into the next one below and so on through the
entire series.
K is a receiver into which the product from the compartment E of the last
electrolytic vat discharges; L is a vertical stand-pipe constituting a carbonator;
M is a vertical branch communicating with the lower end of the stand pipe; N is
a pump; O is a supply pipe connecting the pump with the receiver K. P is a

page_text: discharge pipe from the pump communicating into the upper end of the stand-pipe
and controlled by a valve P Q is an overflow pipe from the branch M into the
soda chamber of the upper electrolytic vat: R is a receiver communicating with
the lower end of the stand-pipe through a valve controlled connection R¹. S is a
centrifugal separator; T is a valve controlled discharge connection from the
receiver into the centrifugal separator, U is the discharge trunk from the centrifugal
separator for the solid products, U₁ is a liquid discharge pipe from the centrifugal
separator into the receiver K. V is a tank provided with a valve controlled
discharge pipe into the centrifugal separator, W is a conveyor; X is a drier; Y is
a grinding mill and Z is a hot blast apparatus, N' is a gas pump; N2 is the discharge
pipe from the pump entering the top of the stand-pipe and extending down inside,
near the bottom of the same, and N³ is the supply pipe of the pump connecting it
with a suitable source of carbonic acid gas.
In practice, the parts being arranged as shown and described they are intended
to operate as follows:
Salt brine from a suitable source is fed into the anode chamber of the upper
electrolytic vat, in quantity to produce a constant overflow and circulation into the
corresponding chamber of the next lower vat and so on through the whole series,
escaping from the last vat to be further treated as a by-product in any desired
manner, not forming a part of this invention.
The cathode or soda compartments of the electrolytic vats, we will suppose for
the present to be filled with pure water, also the receiver K, stand-pipe L' and its
branch M.
In establishing now the electrolytic action it will be seen that the fresh water in
the cathode compartments of the electrolytic vats will become impregnated with
the caustic soda, and if we now set the pump N to work, the contents of one
chamber will gradually overflow into the one next below and so on through the
entire series, into the receiver K.
The pump N being now in continuous operation, the solution of caustic soda will
be gradually delivered through the pipe P into the top of the stand-pipe and from
there by displacement into the leg M and through the pipe Q back into the cathode
chamber of the uppermost vat, thus forming a complete circulation of the liquid
through the cathode chambers, stand-pipe and branch M.
The pump N¹ being set in operation and connected with a suitable source of
supply of carbonic acid gas (which may be produced in the usual manner by
combustion of carbon) the gas is injected through the pipe N2 into the stand-pipe
from which it escapes near the bottom of the stand-pipe and passes up through the
liquid, its quantity being sufficient to convert all the caustic soda contained therein
into bicarbonate.
Should the concentration of the solution be sufficient to form a precipitate
bi-carbonate of soda it would fall to the bottom of the stand-pipe, while the
bi-carbonate in solution would find its way up through the branch M and discharge
pipe back into the electrolytic vats. Here coming in contact and mingling with
the caustic soda produced therein it would be transformed into mono-carbonate of
soda and pass as such into the receiver K, from which it would be again delivered
In the
into the stand-pipe and subjected to the repeated process of carbonation.
continuous operation of the apparatus we would have thus a constant supply of
mono-carbonate of soda into the stand-pipe and converted therein by the constant
supply of fresh carbonic acid gas into bicarbonate of soda, and all the bi-carbonate
which remains in solution is constantly returned into the cathode chambers of the
electrolytic vats and re-converted into mono-carbonate by the additional supply of
caustic soda.
The precipitate of bi-carbonate of soda will collect in the bottom of the stand-
pipe, or if the valve R' is dispensed with or left open it will collect into the
receiver R and from there it may be discharged at suitable intervals into the
centrifugal separator S.
This separator is intended to operate in the usual manner to remove the liquid

page_text: from the solid matter, the liquid being returned through the pipe into the-
receiver K.
The precipitate of bi-carbonate is discharged and transformed by the conveyor W
into the drying apparatus, which may be of any suitable description, the drying
being preferably effected therein by passing through it a mixture of hot air and
carbonic acid gas from the apparatus Z, the material being received in a suitably
dried condition is discharged into a suitable grinding mill from which it leaves as a.
commercial product.
My invention is not limited to the use of any particular electrolytic vat, however,
I prefer to use an electrolytic vat in which an effective separation is obtained by
a diaphragm between an anode and cathode chamber. Should, however, any traces.
of salt find its way into the product of the cathode chambers and from there into.
the bi-carbonate of soda, it may be removed by treating it in a centrifugal separator
by the use of a suitable washing fluid, such as a solution of bi-arbonate of soda.
introduced from the tank V.
It will further be seen that in my construction of apparatus, the bi-carbonate of
soda is precipitated in a medium or body of a solution of bi-carbonate of soda,
owing to making the stand pipe of great height and capacity relatively to the amount
of bi-carbonate produced and by introducing the carbonic acid gas near the bottom
and the monocarbonate near the top, whereby the latter is entirely converted into
bi-carbonate before it reaches the bottom.
By using a suitable number of electrolytic vats and supplying the same with a
continued and ample supply of salt brine, and by a proportionate supply of fresh
water into the cathode compartment to replace the loss by decomposition and
evaporation my apparatus will work on the continuous plan.
It will be understood that by charging the apparatus at the start with a solution
of mono-carbonate or bi-carbonate of soda, the time for obtaining its normal
operation is correspondingly shortened.
My invention includes a distinct sub-process of making mono-carbonate of soda,
This is au
by charging the cathode chambers with a solution of bicarbonate.
important advantage as it reduces the electrical horse power required to electrolize
the salt to a minimum on account of the chemical affinity of the bi-carbonate and
the caustic soda.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The process of producing bi-carbonate of soda, which consists in electrolyzing
salt brine in an electrolytic apparatus organized for the continuous production of
an aqueous solution of caustic soda, converting the product from the soda compart-
ment into bi-carbonate of soda by conducting it into a carbonator, removing the
precipitate of bicarbonate soda from the liquid and recharging the soda compart-
ment of the electrolytic apparatus with bi-carbonate in solution from the
carbonator.
2. Obtaining mono-carbonate of soda in solution as a product from the electrolysis
of salt brine, by supplying the anode chamber or chambers of an electrolytic
apparatus with salt brine, and the cathode chamber or chambers with a solution of
bicarbonate of soda.
3. Obtaining a constant increment of mono-carbonate of soda in a given quantity
of solvent, by treating the product from the cathode chamber of an electrolytic
apparatus organized for the continuous production of caustic soda from salt brine,
with carbonic acid gas in a carbonator, and returning the liquid solution of
bicarbonate of soda to the cathode chamber of the apparatus.
4. In an apparatus for the manufacture of bi-carbonate of soda, the combination
of an electrolytic apparatus organized for the continuous production of caustic soda
in solution, a carbonator, connected in circuit with the cathode compartment of the
electrolytic apparatus and provided with means for supplying it with carbonic acid

page_text: gas, means for circulating the liquid through the carbonator and cathode. compart-
ment and a discharge outlet at the bottom of the carbonator.
5. In a plant for manufacturing bicarbonate of soda, the combination of the
vertical series of electrolytic vats organized for the continuous production of caustic
soda from salt brine and connected by suitable feed and discharge pipes for the
flow of the liquid through the compartments, the receiver K into which the product
of the cathode compartments is discharged, the carbonator L provided with the
branch M, the carbonic acid gas pipe N extending to the bottom of the carbonator,
the return pipe Q from the branch M to the electrolytic vats, the pump N for
maintaining the liquid in circulation, and the receiver R communicating with the
carbonator.
Dated this 10th day of February 1895
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.