Improvements in the Manufacture of Refined Bicarbonate of Soda.
Year: 1893

page_text: Date of Application, 12th Dec., 1893
Complete Specification Left, 11th Oct., 1894-Accepted, 17th Nov., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Refined Bicarbonate of Soda.
I, GUSTAV JÁRMAY of Winnington in the County of Chester, Manufacturing
Chemist, do hereby declare the nature of this invention to be as follows:-
This invention relates to the manufacture of bicarbonate of soda of great purity
from the crude bicarbonate obtained by the ammonia soda process.
One process
of doing this is set forth in Solvay's Patent No. 173 of 1888. The crude
bicarbonate always contains a certain quantity of sodium chloride, of insoluble
matter, and of ammonia, which it is my object to separate, and at the same time
to recover the ammonia more effectually and economically than has heretofore
been done.
In previous Patent No. 2996 and dated 9 February, 1884, my co-patentee and
self have described a process, which consisted in dissolving the crude bicarbonate
at a temperature of 60 degrees centigrade so as not to drive out any carbonic acid,
clarifying the solution and obtaining a pure product by refrigeration; the ammonia
then remained in the mother liquor, and a considerable quantity of it was lost, by
the exposure of the solutions to the atmosphere. The mother liquor had again
to be heated to the required temperature for dissolving the required amount of
crude bicarbonate by blowing steam into it, and was thereby much diluted, so that
the quantity of this mother liquor which had to be evaporated at considerable
cost, to
recover the ammonia and sodium salts contained in it, was very
With the view of obviating these drawbacks of this previous process, I now
propose to effect the solution of crude bicarbonate in a closed vessel provided with
an agitator, and heated by a steam coil, so that the steam no longer dilutes the
solution, and at a temperature of 85 to 95 degrees centigrade. At this temperature,
nearly the whole of the ammonia is driven out of the solution and can easily be
collected. I utilise the steam, and cool the ammonia and other gases given off in
this vessel by taking them through a coil or multitubular cooler surrounded by the
mother liquor from a previous operation.
considerable.
At the temperature named, a certain quantity of carbonic acid is driven out of
the bicarbonate, and the solution obtained consists of a mixture of bicarbonate
and sesqui carbonate of soda, to which carbonic acid has to be added to reconvert
it all into bicarbonate. In order to get rid of the insoluble matter, I filter press
the hot solution, and pass it into an iron tower, divided into numerous compart-
ments and provided with internal cooling pipes, more particularly in the upper
parts of the tower, through which I pass water, so as to reduce the temperature of
the solution to about 40 degrees centigrade. The solution enters this tower near
the top, leaving it near the bottom, while, at the same time, a current of carbonic
acid gas is passed through in the opposite direction. For this purpose, the
carbonic acid gas given off during the preparation of the solution may be used,
but this gas being very pure, it would be completely absorbed in the bottom
compartments of the towers and there would consequently be no agitation going
on in the upper compartments of the towers when the dissolved bicarbonate
crystallises out of the solution as this is being cooled. The cooling pipes would.
in this way, crust up very rapidly, in fact the bicarbonate crystallising out would
almost entirely stick to these cooling pipes, and would very soon stop the proper
action of the tower. I, therefore, prefer to use a carbonic acid gas diluted with
inert gases, such as is obtained from lime-kilns, in order to maintain a sufficient
amount of agitation in the upper part of the towers.

page_text: The bicarbonate, which is in this way separated from the solution, partly by
crystallisation (through the cooling of the solution) and partly by precipitation
through the action of carbonic acid, is separated from the liquor leaving the tower
by filtration or decantation.
These towers crust rapidly, and want frequent cleaning. For this purpose, I
pass through them the mother liquor from previous operations, heated to about
80 degrees centigrade, by means of steam coils or other similar apparatus, which
mother liquor.is .then-taken to the dissolvers to be saturated with crude
bicarbonate.
The bicarbonate, separated from the liquors leaving the towers, is dried and
prepared for the market in any well known manner.
Dated this 9th day of December 1893.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Refined Bicarbonate of Soda.
I, GUSTAV JÁRMAY of Winnington in the County of Chester, Manufacturing
Chemist, 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 manufacturé of bicarbonate of soda of great purity
from the crude bicarbonate obtained by the ammonia soda process.
One process of
doing this is set forth in Solvay's Patent No. 173 of 1888. The crude bicarbonate
always contains a certain quantity of sodium chloride, of insoluble matter, and of
ammonia, which it is my object to separate, and at the same time to recover the
ammonia more effectively and economically than has heretofore been done.
In a previous Patent No. 2996 dated 9th February, 1884, my co-patentee and
self have described a process which consisted in dissolving the crude bicarbonate
at a temperature of 60 degrees centigrade so as not to drive out any carbonic acid,
clarifying the solution and obtaining the pure product by refrigeration; the
ammonia then remained in the mother liquor, and a considerable quantity of it was
lost by the exposure of the solutions to the atmosphere. The mother liquor had
again to be heated to the required temperature for dissolving the required amount
of crude bicarbonate by blowing steam into it, and was thereby much diluted, so
that the quantity of this mother liquor which had to be evaporated at consider-
able cost, to recover the ammonia and sodium salts contained in it, was very
considerable.
Now this invention has for its object to obviate these drawbacks of this previous
process. It will be best understood by referring to the accompanying drawing in
which :-
A is entrance of carbonic acid gas from pump.
pipe for exit gases.
C pipe for strong carbonic.acid gas.
"
"
25
E
F
BOADIGHINKL
J
وو
"
وو
"
pipe for cooled strong carbonic acid gas.
filter for refined bicarbonate.
mother liquor pipe.
warm mother liquor pipe.
feeder for crude bicarbonate.
dissolver for same.
"pump from dissolver.
K,, saturating tower.
L,, cooling coils.

page_text: I effect the solution of crude bicarbonate in a closed vessel or dissolver I
provided with an agitator and fed through hopper H and heated by extraneous
heat, preferably by a steam coil, so that the steam no longer dilutes the solution,
and at a temperature of 85 to 95 degrees centigrade. At this temperature, nearly
the whole of the ammonia is driven out of the solution and can easily be collected.
I utilise the steam and cool the ammonia and other gases given off in this vessel I
by taking them by means of pipe C through the coil or multitubular chamber M
surrounded by the mother liquor from a previous operation and by means of which
the latter is heated.
The cooled carbonic acid gas passes out at D.
At the temperature named, a certain quantity of carbonic acid is driven out of
the bicarbonate, and the solution obtained consists of a mixture of bicarbonate and
sesqui carbonate of soda, to which carbonic acid has to be added to reconvert it
all into bicarbonate. In order to get rid of the insoluble matter, I filter press the
hot solution, and pass it by means of pump J into the iron tower K which is
divided into numerous compartments and provided with internal cooling pipes L,
more particularly in the upper parts of the tower, through which I pass water, so
as to reduce the temperature of the solution to about 40 degrees centigrade.
The solution enters this tower near the top, leaving it near the bottom, while, at
the same time a current of carbonic acid gas is passed through in the opposite
direction through pipe A. For this purpose the carbonic acid gas given off during
the preparation of the solution may be used, but this gas being very pure, it
would be completely absorbed in the bottom compartments of the towers and there
would consequently be no agitation going on in the upper compartments of the
towers when the dissolved bicarbonate crystallises out of the solution as this is
being cooled. The cooling pipes would in this way, crust up very rapidly, in fact
the bicarbonate crystallising out would almost entirely stick to these cooling pipes,
and would very soon stop the proper action of the tower. I therefore prefer to
use a carbonic acid gas diluted with inert gases, such as is obtained from lime kilns,
in order to maintain a sufficient amount of agitation in the upper part of the
towers. B is the pipe for exit gases.
The bicarbonate, which is in this way separated from the solution, partly by
crystallisation (through the cooling of the solution) and partly by precipitation
through the action of carbonic acid, is separated from the liquor leaving the tower
by means of filter E or by decantation.
These towers crust rapidly, and want frequent cleaning. For this purpose, I
pass through them the mother liquor from previous operations, heated to about
80 degrees centigrade, by means of steam coils or other similar apparatus, which
mother liquor is then taken along pipe F, through heater M and along pipe G to
the dissolvers I to be saturated with crude bicarbonate.
The bicarbonate separated from the liquors, leaving the towers, is dried and
prepared for the market in any well known manner.
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 [
claim is :-
In the manufacture of refined bicarbonate of soda the improvements on the
processes set forth in Patent Specifications Nos. 2996 of 1884 and 173 of 1888,
which consist―
(1) In dissolving the bicarbonate in a closed vessel provided with an agitation
device and heating to about 85 to 95 degrees centigrade by extraneous heat,
preferably a steam coil, instead of passing steam into the solution, whereby nearly
the whole of the ammonia is recovered and only a part of the carbonic acid
liberated, while the amount of mother liquor made is greatly reduced.
(2) Utilising the heat of the gases thus given off for heating the mother liquor
of a previous operation.
(3) Re-carbonating by means of limekiln-gas or other dilute carbonic acid,

page_text: whereby the pure carbonic acid given off with the ammonia during the solution can
be otherwise utilized and the working of the process is improved by the agitation
caused by the inert gases contained in the dilute carbonic acid.
(4) Cleaning the re-bicarbonating towers by passing through them the mother
liquors from previous operations heated to about 80° C.
Dated this 10th day of October 1901
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Birmingham, Nottingham, and London,
Patent Agents.