Improvements in the Manufacture of Bicarbonate and Carbonate of Soda; by the Ammonia Process and in the Construction and Use of Apparatus for that Purpose.
Year: 1886

page_text: Date of Application, 25th Nov., 1836.
Complete Left, 10th Aug., 1887.
Complete Accepted, 13th Sept., 1887.
Improvements in the Manufacture of Bicarbonate and Carbonate
of Soda; by the Ammonia Process and in the Construction and
Use of Apparatus for that Purpose.
I WILLIAM BURNS of 32 Elmwood Terrace, Leith, in the County of Mid-Lothian,
Consulting Engineer and Chemist do hereby declare the nature of my said invention
for IMPROVEMENTS IN THE MANUFACTURE OF BICARBONATE AND CARBONATE OF
SODA; BY THE AMMONIA PROCESS AND IN THE CONSTRUCTION AND USE OF APPARATUS
FOR THAT PURPOSE to be as follows:—
The well known ammonia process consists in decomposing salt by passing ammonia
and carbonic acid through a solution of chloride of sodium, but there has hitherto
been considerable difficulty felt in recovering the whole of the ammonia used, in a
condition fit to to be used over again. By my invention the whole of the ammonia
used in decomposing the salt can be recovered and used over and over again without
any loss; and crude ammoniacal liquor from Gas works can be used in the process as
well as the refined salts of ammonia. I use a steam tight boiler and a set of close
cylinders capable of standing a working pressure of from 3 to 4 atmospheres, I fill
the boiler with a Solution of the salts of ammonia or Gas liquor, and raise the
temperature to about 270° Fah. I pump the ammoniacal liquor regularly and
constantly into the boiler so as to keep up a regular overflow of hot liquor from the
top of the boiler into steamtight cylinders where it meets and mixes with a shower of
milk of lime; which liberates the ammonia from the liquor. The ammonia and a
portion of the steam is conducted by an ascending pipe from the liming vessel into an
elevated vessel containing ground rock salt; the steam and ammonia in passing
through the salt vessel is condensed; and dissolves part of the salt which runs down
into a second vessel called the mixing vessel; filled with a saturated solution of
chloride of sodium; into this mixing vessel I pump regularly and constantly a
saturated solution of chloride of sodium, and the overflow is made to run down into a
condenser and from the condenser into a decomposing and precipitating vessel. At
the same time that the ammonia is passing through the salt solution I force a constant
current of carbonic acid through the solution.

page_text: I obtain the carbonic acid from chalk or limestone burned with charcoal in a close
blast retort under high pressure. In the centre of the salt solution vessel, I place a
frame of agitating balls and caps through which the liquor and gases are forced; the
agitation caused by the rising and falling of the balls into the cups causes a rapid
combination and decomposition to take place between the different elements in the
vessels and the result is a precipitation of bicarbonate of soda in the bottom of the
precipitating vessel and a solution of chloride of ammonium in the decomposing
vessel. The precipitate is washed in clean water and filtered, then packed in drums
ready for the market as bicarbonate of soda, or the drums of bicarbonate may be put
into close retorts at a red heat and reduced to carbonate of soda, that is, refined alkali;
the carbonic acid being utilized by forcing it into the solution of salt. The liquid
chloride of ammonium from the decomposing vessel is then pumped into the boiler
and liming vessels where the ammonia is driven off and used over again.
The novelty of this invention consists, First in heating a solution of salts of
ammonia to a high temperature in a close boiler, and in runing the hot liquor into a
separate close vessel where it meets with and mixes with a shower of milk of lime,
which drives off the ammonia under high pressure into a solution of chloride of
sodium.
Second In the use of cup and ball agitators in the mixing and decomposing vessels.
Dated this 24th day of November 1886.

page_text: Improvements in the Manufacture of Bicarbonate and Carbonate
of Soda; by the Ammonia Process and in the Construction and
Use of Apparatus for that Purpose.
I, WILLIAM BURNS, of 32 Elmwood Terrace, Leith, in the County of Mid Lothian,
Consulting Engineer and 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 :-
The well-known ammonia-process consists in decomposing salt by passing ammonia
and carbonic acid through a saturated solution of chloride of sodium, but there has
hitherto been considerable difficulty felt in recovering the whole of the ammonia in a
condition fit to be used over again. By my invention, the whole of the ammonia used
can be recovered and used over again without any loss; and crude ammoniacal liquor
from gas-works can be used in the process as well as the refined salts of ammonia. I
use a steam tight boiler and a set of close cylindrical vessels capable of sustaining a
working pressure of from 3 to 4 atmospheres.
1 fill the boiler with a solution of salts of ammonia or gas liquor, and raise the
temperature to about 270 degrees Fah. 1 pump the ammoniacal liquor regularly and
constantly into the boiler so as to keep up a regular overflow of hot liquor from the
top of the boiler into steam-tight cylinders, where the liquor meets and mixes with
a shower of milk of lime which liberates the ammonia from the liquor. The ammonia
and a portion of the steam is conducted by an ascending pipe from the lining cylinder
into an elevated vessel containing ground rock salt; the steam and ammonia in
passing through the salt vessel is condensed, and dissolves part of the salt, which runs
down into a second vessel called the mixing vessel which is filled with a saturated
solution of chloride of sodium; into this mixing vessel, I pump regularly and
constantly a saturated solution of slt, and the overflow is made to run down into a
condenser, and from the condenser into a decomposing and precipitating vessel. At
the same time that the ammonia is passing through the salt solution I force a constant
current of carbonic acid through the solution. I obtain the carbonic acid from chalk
or limestone burned with charcoal or coke in a close blast retort under high pressure.
In the centre of the salt solution vessel, also in the decomposing vessel, I place a frame
of agitating balls, with cups, through which the liquor and gases are forced; the
agitation caused by the rising and falling of the balls in the cups causes a rapid
combination and decomposition to take place between the different elements in the
vessels and the result is a precipitation of bicarbonate of soda in the bottom of the
precipitating vessel, and a solution of chloride of ammonium in the decomposing
vessel. The precipitate is washed in clean water and filtered and then packed in

page_text: drums ready for the market as bicarbonate of soda, or the drums of bicarbonate of
soda may be put into close retorts at a red heat and reduced to carbonate of soda
(refined alkali) the carbonic acid being utilized by forcing it into the solution of salt.
The liquid chloride of ammonium from the decomposing vessel is pumped into the
boiler and liming vessels where the ammonia is driven off and used over again.
The novelty of this invention consists-First-In heating a solution of salts of
ammonia to a high temperature in a close boiler, and in running the hot liquor into a
separate close vessel where it meets and mixes with a shower of milk of lime which
drives off the ammonia under high pressure into a solution of chloride of sodium.
Second in the use of cup and ball agitators in the mixing and decomposing vessels.
Referring to the drawings, Sheets 1 and 2. A is a boiler for heating liquor under
high pressure, B and Care steam tight vessels, C is divided into compartments by
shallow trays with a number of short overflow tubes t, D¹ is a purifying vessel
containing oxide of iron on perforated trays, E¹ is the salt solution tank for dissolving
chloride of sodium, G, H, L, and ✗, are multitubular condensers, F is a vessel for
holding rock salt, or crystalized chloride of sodium, I is a mixing vessel containing
a frame of cup and ball agitators, N is a decomposing and precipitating vessel
containing cup and ball agitators, Z is a discharging vessel. Fig. 3 on sheet 1 is a
drum made of sheet iron about 3ft. 6in. long by 18 inches diameter with a per-
forated tube fixed in the centre.
In using the above apparatus, I fill the boiler B with a solution of ammoniacal salts
or Gas-liquor, I heat the liquor up to about 270 degrees Fah. The liquor is made to
overflow by constantly pumping the liquor into the bottom of the boiler by the
pump p. The hot liquor overflows by the syphon pipe D, and part runs down the
pipe, a, and enters the vessel B at the bottom, the larger portion runs down the
pipe E into the vessel C. The vessel B is filled with slaked lime and the small stream
of hot liquor entering under the perforated plate X forces its way up through the
lime dissolving a portion of the lime and carrying it forward in the form of milk of
lime into the top of the vessel C, the milk of lime and overflow liquor from the boiler
falls in a shower through the perforated plates t, t, and falls through the valve u' into
the discharging vessel Z. The lime decomposes the ammoniacal liquor and liberates
the ammonia which passes up the pipe E, and enters the vessel F, which is filled with
ground rock salt or crystalized chloride of sodium. B' is a bench of iron retorts
charged with limestone from which the carbonic acid is driven off under high pressure
by heat and superheated steam. The carbonic acid passes up the pipes b and down c
into the wash vessel c¹ where it is washed with water by rising through the agitating
cup and ball frame, the gas then rises up through the pipe d' and along g, into the
vessel F, where it mixes with the ammonia and steam from the vessel C. The mixed
gases and steam force their way down through the salt and escape by a number of
perforated tubes P, fixed in the body of the vessel; the condensed steam dissolves a
portion of the salt and passes along with the gas into the condenser G, into which a jet
of saturated solution of salt is injected by the pump P. The salt solution, ammonia, and
carbonic acid, flow from the vessel G along the pipe H into the mixer I, and are
forced up through a frame of agitating balls in cups inarked k; the rising and falling of
the balls in the cups causes a thorough mixture, and absorbtion of the gases by the
liquid. The solution then passes through the valve V' and down the pipe K into the
condenser L, the cooled liquor then passes down the pipe M and enters the vessel N
by passing through the agitating cup and ball frame ¹, (shown on a larger scale by
Fig. 4). Precipitation of bicarbonate of soda takes place in the upper part of the
vessel N, and the precipitate falls down through the tube n, into the vessel U. The
unabsorbed gases pass through the valve R into the annular space formed by the
jacket J, where the gases expand and keep the vessel N cool. The expanding gases
pass from J, up the pipe Q and enter the chamber L' then up the tubes m, and down
into the vessel Y which is filled with dilute sulphuric acid where any ammonia which
escapes from the vessel N is absorbed by the acid; any liquor that overflows from the
vessel N is delivered by the syphon pipe w into the tank T. As soon as the vessel N is
filled the flow into it should be shut off, and the liquid allowed to settle and

page_text: precipitate for about four hours, then the liquor consisting of a solution of chloride of
ammonium holding some bicarbonate of soda in suspension is drawn off by the cock
into the tank T where the precipitation takes place. After emptying the vessel N,
the precipitate is drawn off from U by the valve V and filtered through the canvas
bag W, and the precipitate from T is filtered through the bag W¹. The solution of
chloride of ammonium is then pumped from the vessels &, s, into the boiler A by the
pump p to be decomposed, and the ammonia used over again. The lime liquor from C,
as it falls into the discharging vessel Z, is relieved from pressure, and any ammonia
that was held in the liquor by pressure in the vessel C, escapes from Z by the pipe b
and enters the condenser ✗, and then down c, into the vessel Y, where it is absorbed ;
the solution of sulphates of ammonia from Y is delivered by the pipe e into the pump
well from which it is pumped into the boiler A. By using duplicate vessels B and N,
the operation can be carried on without intermission; when one vessel is emptying
the other could be filling. The bicarbonate of soda is washed in the filter bags, then
dried and packed in the drums shown in section in Fig. 3, the centre tubes in the
drums is perforated with a number of small holes to allow the gas to escape; the packed
drums are then put into the retorts B' and the doors closed until the drums and
contents are raised to a red heat, which reduces the bicarbonate to carbonate, the
carbonic acid escaping through the perforated tube in the centre is conveyed into the
vessel F. In working upon a large scale these retorts should be kept expressly for
the decomposition of bicarbonate and the extra carbonic acid required should be
obtained from limestone burned with charcoal or coke in an upright retort. The
discharge of the carbonic acid from the carbonates is facilitated by a blast of
superheated steam being blown through the retort. An excess of carbonic acid and
ammonia should in all cases be used and the excess of acid as it escapes from the
vessel Y, should be pumped back into the vessel E, by a force pump.
It will be observed that the whole operation being carried on in closed vessels there
can be no loss of ammonia. In fact one portion of ammonia can be made to
decompose an indefinite quantity of salt. The limestone is first made to give up its
carbonic acid to the ammonia and soda, and the lime is afterwards used to decompose
the ammonia salts.
When crude ammoniacal liquor from gas-works is used in the above process it is
necessary to purify the liquor, gases, and vapours, before passing them through the
salt solution. For that purpose, I use the additional vessels H, G, C, and D'. The
sulphuretted hydrogen, free carbonic acid, ammonia, and naphtha, along with steam,
pass from the boiler A, into the condenser H, where the steam and naphtha is
condensed and run down into the vessel G¹. The sulphuretted hydrogen and carbonic
acid pass down the pipe e¹, and enter the vessel D¹, at the bottom, and pass out by the
pipe g, into the vessel F. The purifier D' is provided with a number of perforated
trays which should be covered to about 6" deep with a mixture of peroxide of iron,
clean iron turnings and charcoal powder, through which the sulphuretted hydrogen
and carbonic acid is made to pass along with a blast of atmospheric air. While the
iron oxide decomposes the sulphuretted hydrogen, part of the hydrogen and carbonic
acid unites with part of the nitrogen injected with the air and forms an additional
quantity of bicarbonate of ammonia, while the oxygen revivifies the iron oxide. A
proper mixture for use in the purifier would be one of iron oxide, one of clean iron
turnings, and two of charcoal powder, by measure. The iron turnings should be
washed in a solution of caustic soda to remove grease, and the charcoal should be in
the granulated state, such as charred sawdust.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is,
1st. I claim the manufacture of bicarbonate and carbonate of soda, by first
decomposing solutions of salts of ammonia by heating the liquor in a close boiler and
running the hot liquor into a separate vessel or vessels containing caustic lime, and
mixing the liquor with a shower of milk of lime so as to liberate the ammonia from
the liquor.

page_text: 2nd. I claim the forcing of the ammonia and steam obtained as above, along with
carbonic acid obtained by the decomposition of limestone, through ground rock salt,
or crystalized chloride of sodium packed in a close vessel around perforated tubes, and
then forcing the gases through a solution of chloride of sodium.
3rd. I claim the use of cup and ball agitators for mixing the ammonia and carbonic
acid with a solution of salt contained in close vessels.
4th. I claim the use of drums with perforated internal tubes in which to pack
bicarbonate of soda to be decomposed by heat-and reduced to carbonate.
5th. I claim the forcing of the sulphuretted hydrogen and carbonic acid driven off
from crude ammoniacal liquor, through a mixture of peroxide of iron, clean iron
turnings, and charcoal powder, along with a blast of atinospheric air contained in close
vessels, which decomposes the sulphuretted hydrogen, and produces bicarbonate of
ammonia to be used in decomposing salt.
6th. I claim the particular combination of boiler decomposing vessels, mixers, and
condensers, constructed and operated substantially as herein described.
Dated this Ninth day of August 1887.
WILLIAM BURNS.