IMPROVEMENTS IN THE MANUFACTURE OF BICARBONATE OF AMMONIA AND SODA
Year: 1877

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF BICARBONATE OF AMMONIA AND SODA." A communi-
cation from abroad by Gustave Guillaume Verzyl, of Louvain, in the Kingdom
of Belgium.
Sealed the 1st February 1878, and dated the 6th December 1877.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 6th December 1877.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent.
"IMPROVEMENTS IN THE MANUFACTURE OF BICARBONATE OF
AMMONIA AND SODA." [A communication from abroad by Gustave Guillaumo
Verzyl, of Louvain, in the Kingdom of Belgium.]
This Invention relates to improved processes for the manufacture of bicarbonate
of soda.
The following is the method of operation:-A solution of sea salt is placed in a
series of closed vessels, into which gaseous ammonia is introduced and dissolved in
the desired proportions. The vessels are placed in communication with each other
in such a way that the gas in excess in the first vessel may pass therefrom to one or
more other vessels, and be dissolved therein. This first operation terminated, the
liquid is made by the pressure of compressed air or carbonic acid to traverso a
perforated false bottom lined with filtering cloth which retains all the insoluble
matters, the liquid passing thence into a series of columns or closed receivers
communicating one with the other like the vessels before-mentioned, and for a
similar purpose. The combination of the carbonic acid with the ammonia is effected
in these columns under pressure which is regulated according to requirements. The
carbonic acid is stored in large chambers made perfectly tight where it becomes
separated from other gases by its density. It is forced into a closed reservoir at a
higher pressure than that in the columus, in order that it may expand on entering
[Price Bd1

page_text: the latter and so cool the liquid. Immediately the bicarbonate of soda is precipi-
tated by the combinations effected in the one column, it is discharged into a closed
filter forming part of said column, and the pressure on the contents of the filter
being still maintained the liquid is caused to traverse said filter, and deposit
therein the precipitated salts mostly composed of bicarbonate of soda. It is then
washed and dried or calcined, according as the salt is to remain in the form of a
bica bonate, or be converted into carbonate of soda.
In order to avoid the clogging of the pipes through which the gases pass from
the columns by the formation and deposit of various salts, washers are used to
eliminate the gases and other matters carried along with the carbonic acid which 1
may not have become absorbed in the vessels, the washing water being utilised for
dissolving the salt.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
6th June 1878.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. " IMPROVEMENTS IN THE MANUFACTURE OF BICARBONATE OF
AMMONIA AND SODA." A communication from abroad by Gustave Guillaume
Verzyl, of Louvain, in the Kingdom of Belgium.
1
This Invention relates to improvements in the manufacture of bicarbonate of 2
soda, and has for its object an economical process of manufacture not requiring the
use of the complicated apparatus generally employed which contain many un-
necessary parts that affect prejudicially both the operation and the quality of the
products.
In order that my Invention may be more readily understood I will describe the 2
process with reference to the annexed Drawing which represents in section one set
of the apparatus employed.
The elements employed in this improved manufacture are,-1st, brine (solution of
chloride of sodium); 2nd, ammonia; 3rd, carbonic acid.
The brine is obtained either from the concentrated waters of salt works, or by 3
dissolving sea salt, or preferably the saline residues of the manufacture of saltpetre,
the operation being effected in a circular vessel provided with a stirrer, and having
a discharge pipe placed a few inches above the bottom, in order that the liquid may
be readily decanted after it has been allowed the necessary time to settle.
The liquid in which the salt is dissolved may either be pure water, or for the 3
sake f economy, water containing a certain proportion of ammoniacal lyes, hydro-
chlorate of ammonia, and bicarbonate of soda, resulting from the washings of this
latter salt and from various apparatus employed. The brine is conducted into a
closed filter F by a pipe a, into which ammonia is pumped through a pipe o beneath

page_text: a perforated plate or false bottom which serves to distribute the gas equally through
the brine, the ammonia being taken by the pump from the ammonia apparatus.
The ammonia, unabsorbed, passes out through a pipe e into a second filter, also con-
taining brine, and if any still escapes unabsorbed, it is conducted into the apparatus
for dissolving the salt. When the brine in the first filter is saturated with ammonia,
a third filter should be brought into use, this third filter then serving the same
purpose in regard to the second filter as the latter did to the first. When the brine
has become sufficiently ammoniacal, and the column C which is to receive it is
empty, the cock on the pipe g, by which these two apparatus are connected is
opened, and either air or carbonic acid gas under pressure is introduced into the
filter through the pipe i from a reservoir in communication with a compressor,
whereby the liquid is immediately driven out of the filter, the impurities remaining
upon the perforated false bottom.
The apparatus in which the dissolved ammonia is converted into bicarbonate,
and the chloride of sodium into bicarbonate of soda, consists of columns C of sheet or
cast iron, well luted and capable of supporting a pressure of several atmospheres,
the exit pipes for the gases being provided with gauges to enable the pressure to be
regulated.
After the columns have been filled with a sufficient quantity of ammoniacal brine,
carbonic acid is introduced therein from a strong reservoir in which it is stored
under pressure, the introduction of the carbonic acid gas being so managed as to
allow of the expansion of the gas (in order to prevent as much as possible the
heating of the liquid); the gas on entering having however a pressure of one or
more atmospheres, according to the stage of the operation, this pressure greatly
facilitating the carbonatation and bicarbonatation of the ammonia and rendering
the process most economical.
If on account of the rapidity of the operation the liquid is insufficiently cooled,
the introduction of carbonic acid into the first column may be suspended for a short
time, and be directed into the second column, supposing the operation to have been
commenced by the first one; the series of columns like the filters F being made to
communicate with each other, so that gas in excess in one may be absorbed in the
next one.
In order to avoid the clogging of the pipes H through which the gases escape
from the columns by the formation and deposit of various salts, two washers B, B¹,
are placed on the exit tube of each column, the first being filled with water, and
the second with acidulated water in which washers are dissolved, the ammoniacal
gases and salts passing off therewith. The liquid fiom the first washer B passes off
through the pipe t into the apparatus for dissolving the salt, in which the carbonate
of ammonia and the bicarbonate of soda contained in the liquid precipitate various
prejudicial foreign matters contained in the brine; the accidulated water from B¹ is
conveyed by the pipe into the ammonia apparatus. The washer B contains
water introduced by pipe K, and it is furnished with a wire gauge diaphragm p to
prevent the liquid being projected towards the exit pipe S, and with a perforated
plate Q placed on the end of pipe H to distribute the gases. V is the exit pipe for
the gases from the small washer B¹; it has two branches by which the gas may be
conducted either into the atmosphere or into another column.
When the bicarbonate of soda is completely formed, which is indicated by a rapid
fall of temperature shown by the thermometer T, the discharge cock is opened and
the contents conveyed through pipe G into a filter F¹ similar to F, except that it is
provided with a safety valve. The discharge cock of this filter remains open, and
the liquid compressed by the gas which is continually being introduced into the
column C is conveyed by the pipe Z and branches z,, either into the lye reservoir,
or partly into the apparatus for dissolving the salt, the precipitated bicarbonate of
soda remaining behind on the false bottom. After the whole of the liquid has
passed out the discharge cock on pipe G is closed, and the column is ready to
receive a fresh charge of ammoniacal brine. The washing of the bicarbonate may
now be commenced. For the first washing either water or the lies resulting from

page_text: the last previous washings may he used, water being used for the succeeding
washings. The liquid is introduced through a rose on the end of pipe w.
It is preferable that the washing water should be heated to from 50° to not more
than 55° C. The water is then expelled and the matters dried by introducing air
or gas under pressure through pipe y, which is also terminated by a rose for
distributing the gas. The bicarbonate is now ready to be dried as bicarbonate, or
to be calcined and reduced to carbonate of soda.
The carbonic acid employed is obtained from limekilns, and should be as pure as
possible, for which purpose it is, after being cooled, conveyed into a large high
covered chamber well lined with cement, where it becomes separated by its superior
density from the lighter gases, which pass off through an opening in the roof.
It is preferable to employ two similar chambers used alternately.
The apparatus above described are those which are deemed most suitable for the
purpose, although any other suitable arrangement may be adopted.
The Drawing represents one set of apparatus for carrying out the series of
operations, but it should be remarked that there should be a number of each of
these apparatus provided with the necessary communications for carrying out the
operations above described; for example, cach column should be supplied by two
filters F, the second of which should as before mentioned be supplemented by a third
when the contents of the first aro saturated. The connection shown between the
washers and the columns will also serve for passing the gas from one column to the
other.
The improved process of this Invention may be thus summarised:-A solution of
sea salt is first placed in a series of closed vessels, into which gascous ammonia is
introduced and dissolved in the desired proportions. The vessels are placed in com-
munication with each other in such a way that the gas in excess in the first vessel
may pass therefrom to one or more other vessels and be dissolved therein. This
first operation terminated, the liquid is made by the pressure of compressed air or
carbonic acid gas to traverse a perforated false bottom lined with filtering cloth
which retains all the insoluble matters, the liquid passing thence into a series of
columns or closed receivers communicating one with the other like the vessels
before mentioned, and for a similar purpose. The combination of the carbonic acid
with the ammonia is effected in these columns under pressure, which is regulated
according to requirements. The carbonic acid is stored in large chambers lined
with cement where it becomes separated from other gases by its greater density; it
is compressed into a closed reservoir to a higher pressure than than in the columns,
in order that it may expand on entering the latter, and so cool the liquid.
Immediately that by the combinations which take place in one column, bicarbonate
of soda is precipitated, the contents of the column are discharged into a closed
filter, forming, so to speak, part of said column, and the pressure on the contents of
the filter being still maintained, the liquid is caused to traverse said filter and
deposit therein the precipitated salts composed for the most part of bicarbonate of
soda. The latter are then washed or dried and calcined, according as the salt is to
remain in the form of a bicarbonate, or be converted into carbonate of soda
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein-before in part recited Letters Patent is,-
1st. The manufacture of bicarbonate of ammonia and soda by introducing
carbonic acid gas at a high pressure into a solution of salt and ammonia contained
in closed vessels, the pressure being regulated by means of cocks and gauges, as
specified.
2nd. The employment of washing apparatus for fiecing of the gasos and other
matters carried along with it, the carbonic acid gas, which not having been
absorbed in one vessel, is to be passed into another, or into the atmosphere, the
washing water which contains useful products being utilised for dissolving the salt,
as specified.
3rd. Employing the pressure of compressed air or carbonic acid gas contained in

page_text: a closed reservoir for discharging from one vessel into another the solid and liquid
matters employed or produced in the apparatus, whether before or after the carbonic
acid treatment, as specified.
4th. Storing the carbonic acid in closed chambers in which it separates by its
superior density from the other gases mixed with it, as specified.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Sixth day of June, in the year of our Lord Onc
thousand eight hundred and seventy-eight.