Carbonic Acid from the Bicarbonate and in Apparatus therefor.
Year: 1887

page_text: Carbonic Acid from the Bicarbonate and in Apparatus therefor.
I, LEONHARD ADOLF STAUB D. Sc. of Northwich, in the County of Chester,
Chemist, do hereby declare the nature of this invention to be as follows:-
This invention relates to the manufacture of mono-carbonate of soda from the
bicarbonate of soda (such as is obtained by the ammonia-soda process) by means of
ammonia or such compounds thereof as are hereafter mentioned in such a way that
a high strength solution of carbonate of soda is obtained directly applicable for the
manufacture of crystallised carbonates of soda and of caustic soda. It is a well
known fact that a complete decomposition of the bicarbonate of soda cannot be
obtained by boiling with water at ordinary pressures. But I have found, that if
ammonia or any of its compounds with carbonic acid or sulphuretted hydrogen be
mixed in solution with bicarbonate and heated to somewhat below the boiling point,
the carbonate of ammonia thus formed or introduced is decomposed into carbonic
acid which escapes, and free or caustic ammonia which partly remains in solution.
The ammonia remaining in solution appears to form again a carbonate at the expense
of the carbonic acid of the bicarbonate of soda, and this in turn to be re-decomposed
and the alternate reactions continued until there remains a solution of mono-carbonate
of soda and of free ammonia, the ammonia acting in fact as a carrier to deprive
the bicarbonate of a part of its carbonic acid. Similar reactions take place, if
ammonia or such compounds as hereinbefore mentioned are passed in gaseous form
through such a solution or mixture at a temperature below the boiling point of the
solution. Pressure favours the reactions inasmuch as it increases the solubility of
the free ammonia at the given temperatures, without affecting the dissociation of the
carbonate of ammonia. In carrying out this invention a convenient way of operating
is as follows:-
•
The bicarbonate such as obtained in the manufacture of ammonia soda may be
mixed with water or with the liquors left after the process has been partly or
completely carried out. This mixture is introduced into a distilling column or
'distiller at or near the top, the kind preferred is one of the type described in

page_text: Solvay's English Patent No. 2143 of 1876, but other modifications thereof are
applicable. The ammonia or such other compound as above described is introduced
at one or more points near the bottom of the distiller, yet sufficiently high up to
prevent any being lost with the run-off liquors. The temperature at that point being
kept above 100 degress C, the ammonia together with the steam introduced or evolved
by the necessary heating appliances at the bottom of the apparatus ascends through
the liquor (which is gradually flowing down from the top of the distiller) and
combines with the bicarbonate contained therein. Of the mixture of carbonate of
soda and carbonate of ammonia thus obtained, the carbonate of ammonia as it reaches
the hotter parts of the distiller becomes gradually decomposed into free ammonia,
which remains in solution, and carbonic acid which ascends through the liquor and
is allowed to escape at the top. As the liquor. reaches the bottom part of the distiller,
owing to the higher temperature, sodium carbonate alone remains in solution, and the
free ammonia which is driven out, ascends and is absorbed by the liquors in the upper
parts of the distiller, and acts again in the manner above described on the bicarbonate.
Thus, if the distiller be once properly started, only sufficient ammonia to make up
for any losses that may occur, need be introduced. The dissociation of the ammonium
carbonate obtained during the process is greatly hastened by agitation, but it will be
generally found that the passage of gases and vapours aided by the form of the
apparatus employed, causes sufficient agitation for the purpose. The soda liquor thus
freed from ammonia and carbonic acid is drawn off by suitable arrangements at the
bottom of the distiller. Instead of-introducing the ammonia near the bottom of the
distiller, the bicarbonate may be sent into the distiller already mixed with solutions
of ammonia, or such compounds thereof as above described, for instance as gas-liquor.
I may also send the bicarbonate into the lower part of the distiller at any convenient
point in the solid form or mixed with the concentrated solution as a semi-liquid mud,
whereby I may be able to obtain solid monocarbonate with the solution. In order to
ensure a complete absorption of the free ammonia by the liquor in the upper parts
of the distiller without absorbing any carbonic acid, it may be advisable to introduce
coils and other well known means to regulate the temperature. The carbonic acid
evolved during the process, and the steam and ammonia which may be carried along
with it, are passed through suitable. cooling apparatus, where, steam and ammonia
are condensed, and the carbonic acid which can thus be obtained perfectly pure, may
be used for the manufacture of pure bicarbonate of soda or any other useful purpose.
The soda liquor thus obtained direct from the bicarbonate generally contains some
organic matter, which can easily be destroyed on applying suitable oxydising agents.
The soda liquor can be used in the ordinary manner for the manufacture of the
different crystallised carbonates, or for caustic soda making, by the well known lime
process.

page_text: Improvements in the Manufacture of Carbonate of Soda and
Carbonio Acid from the Bicarbonate and in Apparatus therefor.
I, LEONHARD ADOLF STAUB, D. Sc. of Northwich, in the County of Chester,
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 manufacture of monocarbonate of soda and almost pure
carbonic acid from the bicarbonate of soda (such as is obtained by the ammonia soda
process) by means of ammonia or such compounds thereof as are hereafter mentioned,
and in such a way that a strong solution of carbonate of soda is obtained, which is
directly applicable for the manufacture of crystallised carbonates of soda, and of
caustic soda. It is a well known fact that a complete decomposition of the bicarbonate
of soda cannot be obtained by boiling with water at ordinary pressures. But I have
found, that if ammonia or any of its compounds with carbonic acid or sulphuretted
hydrogen be mixed in solution with bicarbonate, and heated to somewhat below the
boiling point, the carbonate of ammonia thus formed or introduced is decomposed
into carbonic acid, which escapes, and free or caustic ammonia which partly remains
in solution. The ammonia remaining in solution appears to form again a carbonate
at the expense of part of the carbonic acid of the bi-carbonate of soda, and this in
turn appears to be redecomposed, and the alternate reactions continued, until there
remains a solution of monocarbonate of soda and of. free ainmonia, the ammonia
acting in fact as a carrier to deprive the bicarbonate of a part of its carbonic acid.
The ammonia remaining in solution may be driven out by boiling. Similar reactions
take place, if ammonia or such compounds as hereinbefore mentioned are passed in
gaseous form through such a solution or mixture at a temperature below the boiling
point of the solution. Pressure favours the reactions in as much as it increases the
solubility of the free ammonia at the given temperatures, without affecting the
dissociation of the carbonate of ammonia.
This invention may be carried out in different ways. A convenient apparatus for
the purpose is shown on the accompanying drawing. In this, A is an upright
cylinder formed of boiler plate or other suitable material. B a gas trap. C tubular
condenser for condensing the steam and other condensible gases, that escape with the
carbonic acid. Da mixer for mixing the bicarbonate with water or with a solution
of carbonate of soda. E is the steam inlet. F bell with serrated bottom placed over.
the steam orifice to divide the steam into numerous streams or bubbles. G blow off
pipe. H small test cocks arranged at intervals, to near the top. 1, I, perforated
diaphragms with serrated edges, to break up the streams of steam and gaseous matter.
J other diaphragms having vertical tubes K to allow the steam and gaseous matter to
rise through. L bell over same, with serrated edge to break up and distribute the
gaseous ascending matters. I tube with its orifice a trifle lower than the orifice,

page_text: of K to allow the liquid to overflow into it and descend. M coil with connections
through the side of the chamber of the cylinder. N cup with serrated edge to
receive the mixed bicarbonate and solution, as it is pumped through the pipe n, from
the mixer D by any suitable pump (not shown). O, pipe carrying the carbonic acid
and waste steam to the gas trap B. P, pipe from gas trap to condenser C. Q, pipe
with cock to return the condensed water from gas trap B to the apparatus. p entrance
of ammonia under pressure. R pressure gauge. S, gas outlet from condenser. Tis
a shaft revolved by bevel gear U or other suitable means. t stirrers on shaft T.
v heating coil surrounding stirrers. W hopper for bicarbonate, w revolving beater
or distributor, to distribute the bicarbonate. It is run by belts from shaft T.
•
entrance for liquor. q exit for mixture.
The mode of action is as follows:
The bicarbonate, such as is obtained in the ammonia soda process, is mixed with
water or with the liquors left after the process has been partly or completely carried
out. This mixing operation is performed at a temperature of about 60 degrees
Centigrade in the closed mixer D provided with the heating cock v and agitator T t.
The treatment of the solution or mixture thus obtained with ammonia, or such
compounds as above described, may be carried out in any of the well known distilling
columns, or in any combination thereof with the absorbing columns or towers used in
the ammonia soda process. The drawing shows a very convenient form of apparatus.
The solution or mixture of the bicarbonate with water or liquors is introduced into
this apparatus at or near the top by a pipe n. The ammonia or such other compound
as above described, is introduced at one or more points as at p near the bottom of the
column, yet sufficiently high up to prevent any being lost with the run off liquors;
the temperature at that point being kept above 100 degrees Centigrade is sufficiently
elevated to prevent the absorption of the ammonia, the latter, together with the steam
introduced at E or evolved by heating appliances at the bottom of the apparatus,
ascends through the liquor, which gradually flows down from the top of the column,
and combines in the zones marked X X with part of the carbonic acid of the
bicarbonate contained therein. The steam can also be introduced directly at the same
point or points. Of the mixture of carbonate of soda and carbonate of ammonia
thus obtained, the carbonate of ammonia as it approaches the lower or hotter parts of
the column becomes gradually decomposed in the zones marked Y Y into free ammonia,
which remains in solution, and into carbonic acid, which ascends through the liquor
and is allowed to escape at the top through the pipe O. As the liquor reaches the
zones Z Z at the bottom part of the column owing to the higher temperature there,
sodium carbonate alone remains in solution, and the free ammonia is driven out and
ascends, being absorbed by the liquors in the upper parts of the column, and again
acting in the zones X X as above described, on the bicarbonate. Thus, if the column
be once properly started, only sufficient ammonia to make up for any losses that may
occur need be introduced. The dissociation of the ammonium carbonate obtained
during the process may be greatly hastened by agitation, but it will be generally
found that the passage of the gases and vapours aided by the form of the apparatus
employed, causes sufficient agitation for the purpose. The soda liquor thus freed
from ammonia and carbonic acid is drawn off by suitable arrangements at the bottom
of the column, such as by a pipe G. Instead of introducing the ammonia near the
bottom of the column, the bicarbonate may be sent into the upper part of the column
already mixed with solutions of ammonia, or such compounds thereof as above
described, as for instance with gas liquor. I may also send the bicarbonate into the
lower part of the column at any convenient point in the solid form, or mixed with a
small quantity of water, or with a concentrated solution of carbonate of soda in the
form of a semi-liquid mud. In this case the resultant liquors collected in the lower
part of the apparatus will contain solid mono-carbonate in suspension. To the
bicarbonate thus introduced, ammonia or any of its compounds may be added to ensure
a speedy decomposition. In order to insure a complete absorption of the free
ammonia by the liquor in the upper parts of the column, without absorbing any
carbonic acid, it may be advisable to introduce coils M or other well known means to

page_text: regulate the temperature. The carbonic acid evolved during the process and the
steam and ammonia which may be carried along with it, are passed through a suitable
cooling apparatus C, where the steam and ammonia are condensed. The carbonic
acid, which can thus be obtained is almost perfectly pure, and may be used for the
manufacture of pure bicarbonate of soda, or any other useful purpose, where impure
carbonic acid would not answer. The soda liquor thus obtained direct from the
bicarbonate, generally contains some organic matter, which can easily be destroyed on
applying suitable oxydising agents. The soda liquor can be used in the ordinary
manner for the manufacture of the different crystallised carbonates or for caustic soda
making, by the well known lime process.
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 mono-carbonate of soda and almost pure carbonic
acid, by heating in presence of ammonia, bicarbonate of soda in water, or in
a solution of carbonate of soda, substantially as described, whereby the ammonia
is used continuously, and on repeated quantities of bicarbonate without removal from
the producer.
2. The application to the manufacture of mono-carbonate of soda and carbonic
acid from the bicarbonate, of columnar apparatus, substantially as described and
illustrated.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
Patent Agents for the Applicant.
Dated this 28th day of February 1000.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
Patent Agents for the Applicant.