IMPROVEMENTS IN THE MANUFACTURE AND TREATMENT OF SODA
Year: 1879

page_text: LETTERS PATENT to Ernest Solvay, of Brussels, in the Kingdom of Belgium,
Manufacturer, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE
AND TREATMENT OF SODA."
Sealed the 25th November 1879, and dated the 16th June 1879.
PROVISIONAL SPECIFICATION left by the said Ernest Solvay at the Office of
the Commissioners of Patents on the 16th June 1879.
ERNEST SOLVAY, of Brussels, in the Kingdom of Belgium, Manufacturer.
PROVEMENTS IN THE MANUFACTURE AND TREATMENT OF SODA."
"IM-
My Invention relates to the manufacture of soda by the process generally known
as the ammonia process, for which Letters Patent were granted to me bearing dato
the 11th December 1863, No. 3131, and the 18th of May 1872, No. 1525, and
which process, as further improved by me, is described in the Specifications of
Letters Patent granted to me bearing date the 8th of March 1876, No. 999; tho
5th of May 1876, No. 1904; and the 20th of May 1876, No. 2143.
The first part of my present Invention relates to the formation of a granular
hydrate of lime, and its applications in the decomposition of hydro-chlorate of
aimonia and the caustification of soda. When quicklime is slaked in the ordinary
way, hydrate of lime is obtained in a pulverulent or pasty state, and the reactions
to be operated upon a liquid by means of the said lime are effected with difficulty.
I have discovered a process by which hydrate of lime is obtained in the form of
lumps or pieces, by using which the said reactions may be operated with great
facility; and the said process consists in slaking the said lime by means of a
solution of chloride of calcium or of chloride of ammonium.
I thus obtain a new sort of hydrate of lime, which I name "granular lime,” and
which differs from other hydrate of lime by its physical constitution. In the manu-
facture of soda the said granular lime may have two important applications.
Firstly. It is applicable to the decomposition of chloride of ammonium by placing a
solution of chloride of ammonium in sufficiently close contact with the said granular
lime, even without beat; the solution of chloride of ammonium will be completely
decomposed, chloride of calcium will be formed, and free ammonia evolved.
In the manufacture of ammonia soda the process of decomposing hydro-chlorate

page_text: of ammonia by lime may thus be separated from that of the distillation of free
ammonia, which two processes have until now been united in one.
This may be effected as follows:-
The granular lime is placed in a suitable apparatus arranged so as to allow the
solution of hydro-chlorate of ammonia which is to be decomposed to pass through
it. When passing out from the said apparatus the liquid contains free ammonia in
solution; it is then conducted to distilling apparatus, in which it is distilled, so as
then to return to the soda manufactory.
The reaction may be facilitated by heat from a furnace or a jet of steam.
Or instead of first forming my granular lime the quicklime may be placed
directly in contact with the solution of hydrochlorate of ammonia as it is produced
in the manufacture of ammonia soda. A certain quantity of the said quicklime is
dissolved, and at the same time ammonia is set free, the remainder of the lime
remaining in grains more or less voluminous according to the nature of the lime.
By this means the operation may be carried on directly and systematically, so
as to utilize all the lime, and at the same time to saturate the liquid completely in
closed vessels, so as to collect the ammonia given off.
For this purpose I use a sort of upright cylinder, which I fill with quicklime and
hydrochlorate of ammonia, the latter entering at the bottom and passing out at the
top of the cylinder after dissolving all the lime it is capable of dissolving. The
quicklime is charged in at the top continuously by means of a distributing wheel,
or a large tap or valve chest provided with troughs, or intermittently by means of
two reservoirs alternately filled and emptied. The unburnt lime and impurities
contained in the lime may be removed from the bottom of the cylinder at about the
same place where the liquid enters it, the entering liquid removing from them the
ammonia in which they are immersed.
When a jet of steam is used to accelerate the reaction the condensed steam may
be made to lexiveate the residuo and to deprive it of ammonia before it leaves the
cylinder. An agitator within the cylinder may be used to stir the granular lime
and hasten its solution.
Insead of one cylinder several successive cylinders may be used to work
systematically. My granular line may also be applied to the caustification of
soda.
For this purpose a heated solution of carbonate of soda is made to pass over a
sufficiently thick layer of my granular lime. The soda becomes completely causti-
fied, and the lime is transformed into carbonate of lime without losing its granular
form, and may be easily lexiviated by passing water upon it once or twice, when it
will be deprived of all or nearly all the soda remaining in it, thus obviating the
tedious and often ineffectual lexiviation now required.
The liquid to be caustified and the granular lime are placed in an upright
cylinder or other suitable vessel, or in successive apparatus so disposed that the
two substances travel in opposite directions.
The said process of caustifying soda is applicable to all processes in use for the
manufacture of soda, and is not confined to the ammonia process.
My Invention relates, secondly, to the purification of brine.
In the Specification of Letters Patent granted to me and bearing date the 5th
day of May 1876, No. 1904, I described a process for precipitating the lime and
magnesia generally contained in brine during the course of the manufacture of
Boda.
The said process, though satisfactory in practice, still often leaves a small quantity
of magnesia in solution in the ammoniacal brinc.
Now this part of my Invention consists in means of removing all or nearly all
the magnesia contained in the said brine by adding thereto a quantity of carbonate
of soda without interfering with the operations being carried on.
For this purpose
I dissolve carbonate of soda in pure water or in brine, either ammoniacal brine or
other brine, and I introduce the solution into the brine immediately after the

page_text: absorption of the ammonia. Nearly all the magnesia in solution is then precipitated
in the form of carbonate of magnesia.
Instead of carbonate of soda carbonate of potash or soluble phosphates, or a mixture
of these salts, inay be employed for the purpose.
Thirdly. My Invention relates to the absorption of ammonia by the brine, and
the introduction into the said brine of the requisite proportionate quantities of
ammonia, which operation is hereinafter called "dosing" the ammonia; and also
to the separation from the ammoniacal brine of the sludge contained therein.
For these purposes I use in the process of making the ammoniacal brine a
regulator and separator combined, by which the too large and too small pro-
portionate quantities of ammonia which may be introduced successively into the
brine compensate each other in the mass under treatment, and the proper dosing of
the brine is thus effected.
The ammonia given off by the process of distillation is conducted into a large
reservoir called the absorbing reservoir, into which natural brine is caused to flow
through a suitable cock or valve; an overflow cock situated near the top of the said
absorbing reservoir allows the ammoniacal liquid with any sludge it may contain
in suspension to flow out of the said reservoir into a second very large reservoir
used for the separation of the sludge from the ammoniacal brine. This second
reservoir is by preference arranged as described in the Specification of Letters
Patent granted to me bearing date the 8th day of March 1876, No. 999.
The liquid in the said second reservoir not being agitated by the introduction of
ammonia, as in the first reservoir, the sludge and impurities it contains in sus-
pension fall continuously to the bottom, from which they are removed from time to
time through a suitable cock or valve, the pressure of the liquid above the said
cocks or valves forcing out the said sludge and impurities to any required place;
and I prefer that they should be conducted to distilling apparatus, so as to collect
the ammonia they contain. An agitator may be used to prevent the sludge from
hardening.
From the said second reservoir the ammoniacal brine which has been clarified by
the setting and removal of the sludge as hereinbefore described passes out through
an overflow at the top of the said reservoir into a third reservoir similar in con-
struction or size to the second reservoir. The said third reservoir being constantly
kept full of ammoniacal brine, in consequence of its large size, will act to regulate
the dosing of the ammonia.
The ammoniacal brine is caused to enter the said third reservoir through a
vertical pipe perforated with holes, and of the same height as the reservoir, or
through several outside pipes opening into the reservoir at different points in its
height, so as to cause the said brine to mix at once and constantly with the whole
mass of liquid in the said reservoir.
At about the top of the said reservoir is an overflow pipe through which the
ammoniacal brine flows freely, and is conveyed away to be submitted to the
carbonatation process.
It will be readily understood that by the arrangement herein before described, the
process is continuous, and the dosing of the ammonia is regular; the large mass
treated gives an average quality of the required strength, and the admission of
natural brine into the absorber may be regulated according to the amount of
ammonia contained in the liquid in the said third reservoir, which liquid represents
the average strength, and will vary but slightly owing to the mass of liquid treated
which corrects any momentary irregularity in the quantity of aminonia intro-
duced.
The volume of the liquid treated in the said reservoirs should be about equivalent
to what is to be treated, say, in twelve hours.
The fourth part of my Invention relates to a mode of effecting the decomposition
and calcination of bicarbonate of soda, so as to reduce it to a neutral carbonate, and
it consists of the apparatus hereinafter described, by which the operation is

page_text: continuous, and the vessels used are closed so as not to allow of the escape of the
carbonic acid evolved.
The said apparatus consists of a long cylinder made of cast or wrought iron, and
heated by a suitable furnace, the flames from which are caused to impinge upon it
throughout its whole length in their passage to the chimney. Moist bicarbonate of
soda is charged into the said cylinder by means of funnel-mouthed tubes opening
into the side of the said cylinder, which tubes are kept full of bicarbonate, so as to
be air tight.
The calcined soda is discharged from the said cylinder through a suitable tube or
duct which extends from the said cylinder to near the ground. The carbonic acid
and vapour of water and ammonia evolved during the operation escapes through a
suitable pipe at the top of the cylinder. The said cylinder is traversed in its
length by a shaft passing through stuffing boxes, one at each end of the cylinder,
the said shaft being provided with arms and scraper blades for the purpose of
stirring and moving forward the bicarbonate, and scraping off from the sides of the
cylinder any matters adhering thereto.
The said scraper blades are hinged to the said arms as described in the Specifica-
tion of my Patent of 18th May 1872, No. 1525, small slops or springs on the said
hinges keeping the scraper blades in their required positions.
The fifth part of my Invention relates to the concentration of the waters from the
distillation of ammonia, and the withdrawal therefrom of the sea salt and of the
chloride of calcium.
When the soda manufactory is situated at a distance from the localities where a
supply of sea salt may be obtained, it is desirable to collect the salt contained in
the distilled waters, and also to obtain the chloride of calcium in the form of a con-
centrated liquid, or in a dry state.
To perform this operation, a large quantity of water would have to be evaporated,
and so much fuel would be consumed that the cost of the operation would render
it profitless.
Now this part of my Invention consists in the two processes hereinafter described
for the treatment of the distilled liquid, by which at a trifling cost, chloride of
sodium on one part, and chloride of calciun on the other part may be obtained.
The first process consists in evaporating the liquid residue of the manufacture in
tubular boilers, such as are described in the Specification of Letters Patont granted
to me on the 5th day of May 1877, No. 1748.
By this means, the same heat which produces steam for the engines, also concen-
trates the residue of the manufacture.
The liquid to be concentrated is fed into the said boilers as ordinary water, but
as it is better that it should not on entering come in contact with the concentrated
liquid already in the boiler, so as to lessen its degree of concentration, I cause the
liquid to enter over the lower collector of the tubes. The soparation of the concen-
trated solution of chloride of calcium and the salt takes place in the decanter
connected with the boiler. The salt forms a deposit and is removed, and the outlet
of the concentrated liquid is regulated automatically by means of a float completely
immersed in the said liquid, and actuated by the difference in its density, the out-
flow being arrested whenever the said liquid is not sufficiently concentrated.
By this means the stoker uced only attend to the feed into the boiler, the outlet
of the liquid therefrom being regulated automatically. The second process consists
of an apparatus for concentrating the liquid outside the boilers. It may be used
cither independently of any concentration in the boilers, or conjointly with a con-
centration in the boilers, by conveying the liquid into it after it has been partially
concentrated in the boilers. The said apparatus consists of a long iron boiler, the
sides of which at one part are inclined or V shaped to near the bottom, where they
form together a semicylinder of relatively small diameter. The said V-shaped sides
of the boiler are heated by a furnace or from any suitable source of heat, the central,
under, or semicylindrical part of which constitutes a sort of longitudinal gutter, in
which the sult is precipitated is not heated.

page_text: The after part of the said boiler is of a semicylindrical shape, a rotatory shaft
provided with a helical blade or with helical arms upon it extends throughout the
Jength of the boiler, and causes the salt precipitated in the bottom gutter to pass
to the semi-cylindrical or hottest end of the boiler, where the concentration of the
brine is greatest, and where a second rotatory shaft is provided with hinged knives
or blades which scrape up the salt and throw it over the side of the boiler, from
which it falls into dryers or lexiviators.
The working of the said boiler is continuous; the liquid to be evaporated is fed
into it at the front end, and the salt is removed, and the concentrated liquid con-
taining only chloride of calcium is drawn off at the other end, whore it may be run
into vessels of any suitable shape, in which it congeals as it cools. In order to
prevent the liquid as it passes through the boiler from becoming mixed, and of
average density throughout, partitions are at certain distances rivetted to the
inclined sides of the boiler, the said partitions extending downwards to the small
semi-cylindrical gutter at the bottom of the boiler, care being taken that they do
not interfere with the action of the revolving arms.
The after or semi-cylindrical part of the boiler is not heated, and in it is fitted a
partition by which the concentrated liquid is kept at rest and may be decanted
completely.
The distilled liquid to be evaporated always contains a certain quantity of lime
in solution. To prevent the said lime from mixing with the precipitated salt, or
from forming incrustations, I saturate the lime with hydrochloric acid, by pouring a
small quantity of the acid into the distilled liquid; by this means chloride of calcium
is formed, which mixes with the chlorido of calcium already in the boiler.
My Invention relates, sixthly, to the systematical lexiviation of the residual salt,
and of the sludge and other matters. The residual salt obtained from the distilled
liquid as hereinbefore described is impregnated with a considerable quantity of the
concentrated solution of chloride of calcium from which it is taken, and it is very
important that the salt should be separated therefrom.
Now this part of my Invention consists in the construction and arrangement of
apparatus as herein after described, in which the said salt is separated from the
chloride of calcium by means of continuous and systematical lexiviation.
One arrangement of apparatus according to this part of my Invention consists of
an elongated trough or vessel, in which two shafts provided with helical blades or
helical arms or vanes rotate in contrary directions, so as to stir up the salt which is
introduced at one end of the vessel, and mix it with the water, which is fed into
the other end of the said vessel, and at the same time cause the salt to move forward
along the whole length of the vessel to the end at which the water flows in, whence
it may be removed with a shovel or by mechanical means; the lexiviating water is
decanted near the end of the vessel where the salt is introduced, and flows out
through an overflow pipe.
Another arrangement of apparatus according to this part of my Invention consists
of a series of semi-cylindrical or curved tanks or vessels side by side, and forming
together a sort of undulating large tank, the ends and sides of which are higher
than the inner partitions separating the several tanks or compartments which
compose it. The semi-cylindrical compartments are in communication one with
the other. In the axis of cach of the said compartments except the last one is a
rotatory shaft provided with scraper blades. The salt is introduced at one end of
the said tank and the lexiviating water at the other end, and whilst the water is
flowing through the tanks the scraper blades upon the rotatory shafts aforesaid stir
up the salt and throw it over from one compartment into the next until it reaches
the end of the tank, whence it may be removed. The water having passed to the
other end of the said tank is decanted, and flows out through an overflow pipe. To
the lexiviating water, at a suitable period of the operation, a certain quantity of
carbonate of soda or ammonia or other soluble carbonate may be added, so as to
decompose the chloride of calcium which is adhering to or combined with the sea
salt, thus causing the salt to be more completely purified,

page_text: The mode of lexiviation hereinbefore described is applicable to the lexiviation of
bicarbonate of soda, of the sludge forined in the purification or the caustification
processes and other operations carried out in the manufacture of soda by the
ammonia process.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Ernest Solvay in the Great Seal Patent Office on the 11th December
1879.
ERNEST SOLVAY, of Brussels, in the Kingdom of Belgium, Manufacturer. “IM-
PROVEMENTS IN THE MANUFACTURE AND TREATMENT OF SODA."
My Invention relates to the manufacture of soda by the process generally known
as the ammonia process, for which Letters Patent were granted to me, bearing dato
the 11th December 1863, No. 3131, and the 18th of May 1872, No. 1525, and
which process as further improved by me is described in the Specification of Letters
Patent granted to me bearing date the 8th of March 1876, No. 999; 5th of May
1876, No. 1904; and the 20th of May 1870, No. 2143.
The first part of my present Invention relates to the formation of a granular
hydrate of lime, and its applications in the decomposition of hydro chlorate of
ammonia and the caustification of soda.
When quickline is slaked in the ordinary way hydrate of lime is obtained in a
pulverulent or pasty state, and the reactions to be operated upon a liquid by means
of the said line are effected with difficulty.
I have discovered a process by which hydrate of lime is obtained in the form of
lumps or pieces, by using which the said reactions may be operated with great
facility, and the said process consists in slaking the said lime by means of a solution
of chloride of calcium or of chloride of ammonium. The chemical reaction takes
place in nearly the same way as if no chloride were used, but by my new process. I
obtain a new sort of hydrate of lime, which I name "granular lime," and which
differs from other hydrate of lime by its physical constitution. In the manufacture
of soda the said granular line may have two important applications,―
Firstly. It is applicable to the decomposition of chloride of ammonium.
I have found that by placing a solution of chloride of ammonium in sufficiently
close contact with the said granular lime, even without heat, the solution of
chloride of ammonium will be completely decomposed, chloride of calcium will be
formed, and free ammonia produced.
In the manufacture of aminonia soda the process of decomposing hydro chlorate
of ammonia by line may thus be separated from that of the distillation of free
ammonia, which two processes have until now been united in one.
This may be effected as follows :-
The lime from the lime-kiln having been slaked by means of chloride of calcium
in solution the granular lime thus obtained is placed in a suitable apparatus

page_text: arranged so as to allow the solution of hydrochlorate of ammonia which is to be
decomposed to pass through it. When passing out from the said apparatus the
liquid contains free ammonia in solution; it is then conducted to special distilling
apparatus, in which it is distilled so as then to return to the soda manufactory.
The apparatus in which the reaction takes place is arranged so as to afford every
facility for the introduction of the lime, and the withdrawal of the double solution
of chloride of calcium and ammonia, and the said apparatus may be arranged so as
if required to be heated from a furnace or a jet of steam for the purpose of facili-
tating the reaction, and any of the well known and generally systematic processes
for causing the reaction of a liquid on solid pieces of matter may be applied to my
process.
Or instead of first forming my granular lime the quicklime may be placed
directly in contact with the solution of hydrochlorate of ammonia, as it is produced
in the manufacture of ammonia soda. A certain quantity of the said quicklime is
dissolved, and at the same time ammonia is set free, the remainder of the lime
remaining in grains more or less voluminous, according to the nature of the
lime.
By this means the operation may be carried on directly and systematically so as
to utilize all the lime, and at the same time to saturate the liquid completely in
closed vessels so as to collect the ammonia given off. For this purpose I use a sort
of upright cylinder, which I fill nearly completely with quicklime and with a
solution of hydrochlorate of ammonia, the latter entering at the bottom continuously
or intermittently, and passing out at the top of the cylinder after dissolving all the
lime it is capable of dissolving. The quicklime is charged in at the top, either
continuously by means of a distributing wheel or a large tap or valve chest pro-
vided with troughs, or intermittently by means of two reservoirs alternately filled
and emptied. The unburnt lime and impurities contained in the lime may be
removed from the bottom of the cylinder at about the same place where the liquid
enters it, the entering liquid removing from them the ammonia in which they are
immersed. When a jet of steam is used to accelerate the reaction the condensed
steam may be made to lexiviate the residue, and to deprive it of ammonia before it
leaves the cylinder.
The residue is thus completely lexiviated before leaving the cylinder, and all the
ammonia remains in the said cylinder or returns to it with the currents of steam, or
the current of steam passing into the apparatus for distilling the ammonia may be
used for the purpose.
An agitator within the cylinder may be used to stir the granular lime and to
regulate or hasten its solution.
Instead of one cylinder several successive cylinders may be used to work syste-
matically.
My granular lime may also be applied to the caustification of soda.
For this purpose a heated solution of carbonate of soda is made to pass over a
sufficiently thick layer of niy granular lime. The soda becomes completely caustified,
and the lime is transformed into carbonate of lime, without losing. its granular form,
and may be easily lexiviated by passing water upon it once or twice, when it will
be deprived of all or nearly all the soda remaining in it, thus obviating the tedious
and often ineffectual lexiviation now required.
By the application of my granular lime to the caustification of soda a saving of
time may also be effected, or a more concentrated caustic solution may be obtained
from the same quantity of lime, for it is easy to carry on the operation syste-
natically, as in the case herein before described. The liquid to be caustified and the
granular lime are placed in an upright cylinder or other suitable vessel, or in
successive apparatus, so disposed that the two substances travel in opposite
directions.
The said process of caustifying soda is applicable to all processes in use for the
manufacture of soda, and is not confined to the ammonia process.
My Invention relates secondly to the purification of brine.

page_text: In the Specification of Letters Patent granted to me, and bearing date the 5th of
May 1876, No. 1904, I described a process for precipitating the lime and magnesia
generally contained in brine during the course of the manufacture of soda. The
said process, though satisfactory in practice, still often leaves a small quantity of
magnesia in solution in the animoniacal brine.
Now, this part of my Invention consists in means of removing all or nearly all
the magnesia contained in the said brine by adding thereto a quantity of carbonate
of soda without interfering with the operations being carried on.
For this purpose I dissolve carbonate of soda in pure water, or by preference
in brine, either ammoniacal brine or other brine, and I introduce the solution into
the brine immediately after the absorption of the ammonia. Nearly all the mag-
nesia in solution is then precipitated in the form of carbonate of magnesia.
It is advantageous to use in this case a quantity of carbonate of soda much
greater than its equivalent of magnesia in solution, and this is not a disadvantage,
as the said soda is returned later on in the manufacture.
Instead of carbonate of soda carbonate of potash, or soluble phosphates, or a
mixture of these salts, may be employed for the purpose.
Thirdly. My Invention relates to a process for the continuous absorption of
ammonia by the brine, and the continuous introduction into the said brine of the
requisite proportionato quantities of ammonia, which operation is hereinafter
called "dosing" the ammonia, and also to the separation from the ammoniacal
brine of the sludge produced in the purification of the brine.
In the manufacture of soda by the ammonia process it has been my constant aim
to obtain a continuous and regular absorption of the ammonia in the brine so as to
provide for the carbonatation, a liquid always fulfilling the necessary conditions.
At first I used a process of "dosing" the ammonia based upon the specific gravity
of the liquid, and subsequently when carbonic acid was found mixed with the
ammonia from the distillation process; and then the difference in the density of the
materials used could no longer be considered as affording a certain basis, I regulated
the dosing according to the increase of volume produced by the absorption of the
ammonia. Since then I have observed that these operations were mostly required
because the liquid merely passed through the absorbing apparatus without remaining
in them, so that there could be no compensation between the quantities of brines
differently charged with ammonia at different times.
This led me to discover that if the vessels used for the purpose were sufficiently
large the said compensation would be easily effected, thus constituting a new self
acting process of dosing, it being only necessary to regulate the exact quantity of
brine or ammonia required to give the proper mixture, at long intervals, when it
would be easy to increase or diminish the proportions, according as the mixture
contained a too great or too small average quantity of one or the other.
It will be readily understood that in the regular course of manufacture as the
quantity of ammonia evolved is pretty nearly the same one day as another, all that
is necessary is to regulate the inflow of natural brine to the absorbing process so
that notwithstanding the variations in the quantity of ammonia arriving at every
moment, after a few hours pretty nearly the same quantity of liquid will be pro-
duced. The use of these large reservoirs of liquid has led to a further improvement.
Up to this time the decantation of the sludge (consisting generally of carbonates of
lime and of magnesia)from the purification of impure brine, either natural brine or
other brine, has been effected alternately in several reservoirs working intermit-
tently, and which were isolated for the decantation, and then set to work again.
The reason why a certain number of apparatus had to be used was that the liquid
to be treated was a passing liquid, in which a solid compound was formed, and that
to enable the solid compound to fall to the bottom, the liquid which had been
treated must be separated from what had not yet been treated. When a sufficiently
large apparatus is used the great mass of liquid is but little affected by the troubled
liquid which is caused to enter at a suitable part of the apparatus, and in its
passage through the apparatus to the other end of it deposits the precipitate it

page_text: contains, by this means the same result is obtained as if several apparatus were
used. This point is very important now that the decantation of the sludge is
effected in the process of the absorption of the ammonia, its application also simpli-
fies that part of the manufacture of soda which consists in preparing and purifying
the ammoniacal brine by operating on masses of liquid so large that the momentary
variations in the absorption of the aminonia are compensated, and the decantation
of the sludge is effected without affecting the other parts of the liquid. For these
purposes I use in the process of making the animoniacal brine a regulator and
separator combined, by which the too large and too small proportionate quantities
of ammonia which may be introduced successively into the brino compensate cach
other in the mass under treatment, and the proper dosing of the brine is thus
effected.
The ammonia given off by the process of distillation is conducted into a large
reservoir called the absorbing reservoir, into which natural brine is caused to flow
through a suitable cock or valve. An overflow cock situated near the top of the
said absorbing reservoir allows the ammoniacal liquid with any sludge it may con-
tain in suspension to flow out of the said reservoir into a second very largo
roservoir used for the separation of the sludge from the ammoniacal brine. This
second reservoir is by preference arranged as described in the Specification of
Letters Patent granted to me bearing date the 8th of March 1876, No. 999.
The liquid in the said second reservoir not being agitated by the introduction of
ammonia, as in the first reservoir, the sludge and impurities it contains in suspension
fall continuously to the bottom, from which they are removed from time to time
through a suitable cock or valve, the pressure of the liquid above the said cocks or
valves forcing out the said sludge and impurities to any required place, and I prefer
that they should be conducted to the distilling apparatus, so as to collect the
ammonia they contain. An agitator may be used to prevent the sludge from
hardening.
From the said second reservoir the ammoniacal brine, which has been clarified by
the settling and removal of the sludge as hereinbefore described, passes out through
an overflow at the top of the said reservoir into a third reservoir, similar in con-
struction or size to the second reservoir. The said third reservoir being constantly
kept full of ammoniacal brine, in consequence of its large size, will act to regulate
the dosing of the ammonia. The aminoniacal brine is caused to enter the said third
reservoir through a vertical pipe perforated with holes, and of the same height as
the reservoir, or through several outside pipes opening into the reservoir at different
points in its height, so as to cause the said brine to mix at once, and consequently
with the whole mass of liquid in the said reservoir. At about the top of the said
reservoir is an overflow pipe through which the ammoniacal brine flows freely, and
is conveyed away to be submitted to the carbonatation process.
It will be readily understood that by the arrangements herein before described the
process is continuous, and the closing of the ammonia is regular; the large mass
treated gives an average quality of the required strength, and the admission of
natural brine into the absorber may be regulated according to the amount of ammonia
contained in the liquid in the said third reservoir, which liquid represents the
average strength, and will vary but slightly, owing to the mass of liquid treated,
which corrects any momentary irregularity in the quantity of ammonia introduced.
The volume of the liquid treated in the said reservoirs should be about equivalent
to what is to be treated, say, in twelve hours.
The fourth part of my Invention relates to a mode of effecting the decomposition
and calcination of bicarbonate of soda, so as to reduce it to a neutral carbonate, and
it consists of the apparatus hereinafter described, by which the operation is con-
tinuous, and the vessels used are closed, so as not to allow of the escape of the
carbonic acid evolved.
The salt is made to travel through a longer distance; hinged scrapers scrape off
from the sides of the apparatus any matter adhering thereto, and move forward the
bicarbonate. A considerable quantity of salt is maintained in the apparatus, so

page_text: that the moist salt as it enters comes in contact with salt already dry and heated,
and mixes directly with it, and the tubes for the introduction of the bicarbonate
are placed at the sides of the apparatus instead of being placed at the top.
The said apparatus, which is ropresented by a longitudinal section in Fig. 1, and
a transverse section in Fig. 2, consists of a long cylinder A made of cast or wrought
iron, and heated by a suitable furnace B, the flames from which are caused to
impinge upon it throughout its whole length in their passage to the chimney C.
Moist bicarbonate of soda is charged into the said cylinder by means of funnel
mouthed tubes D, D¹, opening into the side of the said cylinder, which tubes are
kept full of bicarbonate so as to be airtight.
The calcined soda is discharged from the said cylinder through a suitable tube or
duct E, which extends from the said cylinder to near the ground.
The carbonic acid and vapor of water and ammonia evolved during the operation
escape through a suitable pipe F at the top of the cylinder.
The said cylinder is traversed in its length by a shaft G passing through stuffing
boxes I, I', one at each end of the cylinder, the said shaft being provided with arms
and scraper blades H, H', for the purpose of stirring and moving forward the
bicarbonate, and scraping off from the sides of the cylinder any matters adhering
thereto. Motion is communicated to the shaft G by means of the toothed wheel K
and pinion L. The said scraper blades are hinged to the said arms, as described in
the Specification of my Patent of 18th May 1872, No. 1525, small stops or springs
on the said hinges keeping the scraper blades in their required positions.
It will be remarked that the bicarbonate entering at one place, or more than one
place, always comes in contact with a mass of material already partially calcined,
and by the arrangement of the apparatus all pasty mixture of the materials may
be prevented as the tubes used for the introduction of the material may be moved
backwards to near the middle of the apparatus if necessary.
In some cases a special furnace on the side where the material enters may be used
to heat the material as it enters.
The fifth part of my Invention relates to the concentration of the waters from
the distillation of ammonia and the withdrawal therefrom of the sea salt and of the
chloride of calcium.
When the soda manufactory is situated at a distance from the localities where a
supply of sea salt may be obtained, it is desirable to collect the salt contained in
the distilled waters, and also to obtain the chloride of calcium in the form of a
concentrated liquid or in a dry state.
To perform this operation a large quantity of water would have to be evaporated,
and so much fuel would be consumed that the cost of the operation would render it
profitless.
Now this part of my Invention consists in the two processes hereinafter described
for the treatment of the distilled liquid, by which, at a trifling cost, chloride of
sodium on the one part and chloride of calcium on the other part may be obtained.
The first process consists in evaporating the liquid rosidue of the manufacture in
tubular boilers, such as are described in the Specification of Letters Patent granted
to me on the 5th day of May 1877, No. 1748. By this means the same heat which
produces steam for the engines also concentrates the residue of the manufacture.
The liquid to be concentrated is fed into the said boilers as ordinary water, but
as it is better that it should not on entering come in contact with the concentrated
liquid already in the boiler, so as to lessen its degree of concentration, I cause the
liquid to enter over the lower collector of the tubes. The separation of the concen-
trated solution of chloride of calcium and the salt takes place in the decanter
connected with the boiler. The salt forms a deposit and is removed, and the outlet
of the concentrated liquid is regulated automatically by means of a float completely
immersed in the said liquid and actuated by the difference in its density, the
outflow being arrested whenever the said liquid is not sufficiently concentrated.
By this means the stoker need only attend to the feed into the boiler, the outlet of
the liquid therefrom being regulated automatically.

page_text: The second process consists of an apparatus for concentrating the liquid outsido
the boilers. It may be used either independently of any concentration in the
boilers or conjointly with a concentration in the boilers by conveying the liquid
into it after it has been partially concentrated in the boilers.
The said apparatus, which is represented in Figs. 3, 4, and 5 of the accompanying
Drawings, Fig. 3 being a transverse section of Fig. 5, which represents a portion of
the said apparatus in longitudinal section, and Fig. 4 boing another transverse
section of Fig. 5, consists of a long iron boiler A, the sides of which at one part are
inclined or shaped to near the bottom, where they form together a semicylinder
of relatively small diameter.
The said V shaped sides of the boiler are heated by a furnace B, B', or from any
suitable source of heat, the central, under, or semicylindrical part which constitutes
a sort of longitudinal gutter in which the salt is precipitated is not heated, so that
all the salt precipitated from the liquid in consequence of the evaporation falls into
that portion of the boiler where the liquid is not stirred up by the boiling. The
after part of the said boiler is of a semi-cylindrical shape.
A rotatory shaft C provided with a helical blade or with helical arms D upon it
extends throughout the length of the boilor, and causes the salt precipitated in the
bottom gutter to pass to the semi-cylindrical or hottest end of the boiler where the
concentration of the brine is greatest, and where a second rotatory shaft E is
provided with arms L and hinged knives or blades P, which scrape up the salt
and throw it over the side F of the boiler, from which it falls into dryers or
lexiviators.
The working of the said boiler is continuous, the liquid to be evaporated is fed
into it at the front end, and the salt is removed, and the concentrated liquid
containing only chloride of calcium is drawn off at the other end, where it may be
run into vessels of any suitable shape, in which it congeals as it cools. In order to
prevent the liquid as it passes through the boiler from becoming mixed and of
average density throughout, sheet iron partitions a, b, c, d, e, are at certain distances
rivetted to the inclined sides of the boiler, the said partitions extending downwards
to the small semicylindrical gutter at the bottom of the boiler, care being taken
that they do not interfere with the action of the revolving arms. The after or
semi-cylindrical part of the boiler is not heated. The salt is collected at H, in
which is fitted a partition f, g, by which the concentrated liquid is kept at rest and
may be decanted completely.
The distilled liquid to be evaporated always contains a certain quantity of lime
in solution.
To prevent the said lime from mixing with the precipitated salt or from forming
ncrustations I saturate the lime with hydrochloric acid by pouring a small quantity
of the acid into the distilled liquid; by this means chloride of calcium is formed
which mixes with the chloride of calcium already in the boiler.
My Invention relates, sixthly, to the systematical lexiviation of the residual salt
and of the sludge and other matters.
The residual salt obtained from the distilled liquid, as hereinbefore described, is
impregnated with a considerable quantity of the concentrated solution of chloride
of calcium from which it is taken, and it is very important that the salt should be
separated therefrom.
Now this part of my Invention consists in the construction and arrangement of
apparatus, as hereinafter described, in which the said salt is separated from the
chloride of calcium by means of continuous and systematical lexiviation.
One arrangement of apparatus, according to this part of my Invention, consists
of an elongated trough or vessel a, represented in longitudinal section in Fig. 6 and
in transverse section in Fig. 7. In the said vessel a two shafts provided with
helical blades or helical arms or vanes rotate in contrary directions, so as to stir up
and move forward the salt which is introduced at one end of the vessel a, and mix
it with the water which is fed into the other end of the said vessel, and at the
same time cause the salt to move forward from A along the whole length of the

page_text: vessel to the end B, at which the water flows in, whence it may be removed with a
shovel or by mechanical means. The lexiviating water which enters at B and flows
on to A is decanted at C near the end of the vessel where the salt is introduced,
and flows out at D through an overflow pipe.
Another arrangement of apparatus according to this part of my Invention, which
is represented in longitudinal section in Fig. 8, and in transverse section in Fig. 9
of the accompanying Drawing, consists of a series of semicylindrical or curved tanks
or vessels A, B, C, D, E, side by side, and forming together a sort of undulating
large tank, the ends and sides of which are higher than the inner partitions, sepa-
rating the several tanks or compartiments which compose it. The semicylindrical
compartments are in communication one with the other. In the axis of cach of the
said compartments, except the last one, is a rotatory shaft provided with scraper
blades, such as are represented in Fig. 4. The salt is introduced at one end E of
the said tank, and the lexiviating water at the other end A, and whilst the water is
flowing through the tanks the scraper blades upon the rotatory shafts aforesaid stir
up the salt, and throw it over from one compartment into the next until it reaches
the end A of the tank, whence it may be removed. The water having passed to the
other end of the said tank is decanted, and flows out through an overflow pipe.
The tank F is used for the decantation of the water.
To the lexiviating water at a suitable period of the operation a certain quantity
of carbonate of soda, or of ammonia or other soluble carbonate, may be added, so as
to decompose the chloride of calcium which is adhering to or combined with the
sea salt, thus causing the salt to be more completely purified.
The mode of lexiviation herein before described is applicable to the lexiviation of
bicarbonate of soda, of the sludge formed in the purification or the caustification
processes, and other operations carried out in the manufacture of soda by the
ammonia process.
Having thus described the nature of my said Invention and the manner of per-
forming the same, I wish it to be understood that I claim as my said Invention of
improvements in the manufacture and treatment of soda,-
Firstly. The application of chloride of calcium or chloride of ammonium to the
slaking of quicklime for the purpose of obtaining granular slaked lime; also the
application of granular lime thus obtained to the caustification of the mother waters
in the manufacture of ammonia soda, that is to say, to the decomposition of the
hydrochlorate of ammonia contained in such mother waters, the lime being either
previously slaked by means of chloride of calcium or slaked during the operation
itself by the chloride of ammonia.
Also, dividing the process of regenerating the ammonia into two distinct opera-
tions, one consisting in caustifying the liquid, and the other in driving out the
ammonia liberated therefrom; also the application of the said granular lime to the
caustification of soda.
Secondly. The addition of carbonate of soda to the brine after the absorption of
the ammonia in order to precipitate the carbonate of magnesia contained in the brine
to be used in the manufacture of soda.
Thirdly. Constructing the vessels in which the ammoniacal brine is to be made
of sufficiently large size, so that the too large and too small proportionate quantities
of ammonia introduced successively in the brine compensate each other in the mass
under treatment, forming a suitable average, so as then to constitute a regular
system of dosing of the ammonia, and that the decantation of the sludge may be
effected continuously without affecting the upper portion of the liquid where the
evacuation takes place; also the combination of this system of continuous dosing of
the ammonia with the system of continuous decantation of the sludge.
Fourthly. The combination, adaptation, and arrangement of parts of apparatus
for the calcination and the decomposition of bicarbonate of soda, substantially as
described, such apparatus being combined and arranged so as to provide a long
course for the travel of the salt, an arrangement of hinged scraper blades for the
cleansing of the sides of the apparatus, and the advance of the material under opera-

page_text: tion to allow of a considerable quantity of salt being maintained in the apparatus,
so that the moist salt on entering comes directly in contact with other salt already
dried and heated, and mixes with it at once; and also an arrangement of tubes for
the admission of the bicarbonate, enabling such tubes to be kept full of salt so as to
be hermetically closed, such tubes being placed not at the top of the apparatus, but
at the sides of the cylinder.
Fifthly. I claim the process, herein before described, of concentrating the waters
obtained from the distillation of ammonia in the manufacture of ammonia soda so
as to collect therefrom the sea salt and the chloride of calcium they contain, either
by treating such waters in a steam boiler forined of tubes disposed in a coil and in
communication with a reservoir for separating the steam, and decanting the sludge,
such as is described in the Specification of Letters Patent granted to me, and
bearing date the 5th day of May 1877, No. 1748, or by treating the said waters in
a continuous apparatus, constructed and arranged substantially as herein-before
described, and illustrated in Figs. 3, 4, and 5 of the accompanying Drawings, the
parts of which apparatus are heated unequally so as to cause the salt precipitated
from the said waters to settle at the bottom, where by mechanical means it is caused
to advance to the furnace end of the apparatus, where it is taken out by mechanical
means at the same time as another arrangement decants the concentrated liquid
from the salt.
Sixthly. The construction and arrangement of parts of apparatus for effecting a
systematic and continuous lexiviation of the residual salt and of the sludge and
other matters, substantially as herein before described and illustrated in Figs. 6 and
7 of the accompanying Drawings; also the construction and arrangement of parts
of apparatus for effecting a systematic and continuous lexiviation of the residual
salts, or the lexiviation of bicarbonate of soda and the sludge formed in the purifi-
cation or the caustification processes and other operations carried out in the manu-
facture of soda by the ammonia process, substantially as hereinbefore described, and
illustrated in Figs. 8 and 9 of the accompanying Drawings.
In witness whereof, I, the said Ernest Solvay, have hereunto set my hand
and seal, this Ninth day of December, in the year of our Lord One thousand
eight hundred and seventy nine.
ERNEST SOLVAY. (L.S.)