IMPROVEMENTS IN THE MANUFACTURE OF SODA AND CHLORINE
Year: 1884

page_text: We CHARLES WIGG of 6 Water Street Liverpool in the county of Lancaster,
Alkali Manufacturer and JOHN WALLER PRATT of Runcorn in the county of
Chester Technical Chemist do hereby declare the nature of our said invention for
IMPROVEMENTS IN THE MANUFACTURE OF SODA AND CHLORINE to be as follows:-
The main object of our improvements is to render the aminonia soda process
more generally applicable than it is at present and to enable it to yield a greater
variety of products. It is a well known and widely recognised fact that the great
drawback to the ammonia soda process is the total loss of the chlorine contained in
the salt manufactured into soda and hence any process which would render the
ammonia process capable of also producing chlorine and bleaching powder is a
great desideratum.
In the Leblanc process half the total chlorine is available for the production of
bleach but in the ammonia process all the chlorine is now run to waste in the form
of chloride of calcium. This chloride of calcium is produced by the decomposition
of the chloride of ammonium liquors with lime an operation which is performed
with a view to the regeneration of free ammonia for a fresh operation. It is the
object of our present invention to deal in another improved manner with these
chloride of ammonium liquors in such a manner as to obtain from them not only
all the ammonia but also all the chlorine they contain in a condition suitable for
the manufacture of more soda and of bleaching powder. This we accomplish as
follows:-
1st The solution of chloride of ammonia obtained in the manufacture of soda
by the ammonia soda process we boil in a closed boiler till all the free ammonia
and ammonic carbonate it contains has been volatilized and we then evaporate it
in suitable pans to complete dryness or till crystals of chloride of ammonia and of
salt at length separate out. The salt when not being detrimental in the subsequent
processes is allowed to remain mixed with the crude dry chloride of ammonia.
2nd The chloride of ammonia I carefully collect into vessels properly adapted
and there mix it with finely ground carbonate of lime in equivalent proportion.
3rd The mixture of carbonate of lime and chloride of ammonia prepared as above
I then transfer to a hemispherical pan heated from beneath and provided with a
tight fitting cast iron hood or dome resting on its upper rim. On heat being applied
to the mixture from beneath carbonate of ammonia is volatilized and sublimed
on to the roof or dome of the pan to which it adheres. The reaction which takes
place when heat is applied to a mixture of chloride of ammonia and carbonate of
.

page_text: lime is this 6 NH, Cl + 3 Ca 00, = 3 Ca Cl, + 2 (NH), 0, 3 CO, + 2 NHg +
H2O or expressed additively 2 NH, Cl + Ca CO₂ = (NH4)2 CO, + Ca Cl. In
place of allowing the carbonate of ammonia to cool on subliming I may maintain
the upper portion of the pan at a high temperature and pass the vapour of carbonate
of ammonia direct into brine to be treated as is subsequently set forth.
4th The residue from the operation which remains in the pan consists of a loose
porous mass of chloride of calcium. While it remains hot in the pan I remove
from the top of it the dome containing the sublimed carbonate of ammonia and
substitute for it another tight fitting cover provided with an escape pipe leading
to a condenser. I then run on to the contents of the pan (chloride of calcium) an
equivalent quantity of strong vitriol. The reaction is Ca Cl₂ + H₂ SO₁ = Ca SO +
2 H Cl. The hydrochloric acid gas disengaged in this reaction I convey as
above said to a condenser where it is converted into acid of suitable strength
Bay 25° T which I use in the ordinary well known way for the manufacture of
chlorine The sulphate of lime I roast at the proper temperature to convert it into
plaster of paris.
5th The carbonate of ammonia produced by (3) I disengage and mix or dissolve
in strong brine in equivalent proportion I then pass into that solution another
molecule of carbonic acid gas. When I say another molecule of carbonic acid gas
I mean such a quantity of gas as will with the carbonic acid already present in
the carbonate of ammonia added form with the salt in the brine bi-carbonate of
soda in the solid state thus (NH)₂ CO, + H₂ 0 + CO2 + 2 Na Cl = 2 Na H CO, +
2 NH Cl. From the above equation it will be noted that there is formed
bi-carbonate of soda and a solution of chloride of ammonia ready to be again
subjected to a fresh series of operations similar to those already described.
By using the carbonate of ammonia in this way we save the expense and trouble
of generating and pumping one half the total carbonic acid needed for the produc-
tion of carbonate of soda.
It will be evident (vide head 2) that in place of the carbonate of limo we use
to react on the chloride of ammonia to produce carbonate of ammonia we may
use the carbonates of barium magnesia or strontin as considered expedient. If
magnesia be used the residue left in the pan after the sublimation will consist of
chloride of magnesia and this salt after decomposition with vitriol will yield the
soluble sulphate of magnesia which may be dissolved in water and crystallized
therefrom to render it marketable. Barium or strontium carbonate used for the
same reaction will leave residues consisting respectively of baric chloride or of
strontic chloride and when this is the case we adopt a slightly different manner
of dealing with these residues. In place of running vitriol on the chloride as it
remains in the sublimation pan we detach it and dissolve it in a suitable amount
of hot water and filter We then run into the chloride solution in suitable tanks
an equivalent quantity of vitriol so as to yield a precipitate of the insoluble
sulphate of barium or strontium and a supernatant solution of hydrochloric acid.
Sulphate of barium prepared in this way is known as blanc fixe and is an article
of considerable commercial value while sulphate of strontium thus obtained is in
such a fine state of sub division as to fit it for many technical applications.
Dated this twentieth day of February 1884
J. T. KING,
Agent for the Applicants.

page_text: We CHARLES WIGG of 6 Water Street Liverpool in the County of Lancaster,
Alkali Manufacturer, and JOHN WALLER PRATT of Runcorn in the County of
Chester Technical Chemist, do hereby declare the nature of the said 'invention
for "IMPROVEMENTS IN THE MANUFACTURE OF SODA AND CHLORINE" and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The main object of our improvements is to render the ammonia soda process
more generally applicable than it is at present and to enable it to yield a greater
variety of products. It is a well known and widely recognised fact that the great
drawback to the ammonia soda process is the total loss of the chlorine contained
in the salt manufactured into soda, and hence any process which would render the
ammonia process capable of also producing chlorine and bleaching powder is a
great desideratum. In the Leblanc process half the total chlorine is available for
the production of Bleach, but in the ammonia process all the chlorine is now run
to waste in the form of chloride of calcium. This chloride of calcium is produced
by the decomposition of the chloride of ammonium liquors with Lime, an operation
which is performed with a view to the regeneration of Free Aminonia for a fresh
operation. It is the object of our present invention to deal with these chloride
of ammonium liquors in such a manner as to obtain from them not only all
the ammonia but also all the chlorine they contain in a condition suitable for
the manufacture of more soda, and of Bleaching Powder. This we accomplish as
follows:-
1st The solution of chloride of ammonia obtained in the manufacture of soda
by the ammonia soda process we boil in a closed boiler till all the free ammonia
and ammonic carbonate it contains has been volatilized and we then evaporate it
in suitable pans to complete dryness or till crystals of chloride of ammonia and of
salt at length separate out. The salt when not being detrimental in the subsequent
processes is allowed to remain mixed with the crude dry chloride of ammonia.
2nd The chloride of ammonia we carefully collect into vessels properly adapted
and there mix it with finely ground carbonate of lime in equivalent proportion.
3rd The mixture of carbonate of lime and chloride of ammonia prepared as above
we then transfer to a hemispherical pan heated from beneath and provided with a
tight fitting cast iron hood or dome resting on its upper rim. On heat being applied
to the mixture from beneath carbonate of ammonia is volatilized and sublined
on to the roof or dome of the pan to which it adheres. The reaction which takes
place when heat is applied to a mixture of chloride of ammonia and carbonate of
lime is this:-6 NH, Ci + 3 Ca CO, = 3 Ca Cl 2 + 2 (NH), O, 3 CO₂ + 2 NH, +
H, O or expressed additively: 2 NH. Cl + Ca CO, (NH), CO, + Ca Cl. In
place of allowing the carbonate of aminonia to cool on sublining we may maintain
the upper portion of the pan at a high temperature and pass the vapour of carbonate
of ammonia direct into brine to be treated as is subsequently setforth.
=
4th The residue from the operation which remains in the pan consists of a loose
porous mass of chloride of calcium while it remains hot in the pan we remove
from the top of it the dome containing the sublimed carbonate of ammonia and
substitute for it another tight fitting cover provided with an escape pipe leading
to a condenser, We then run onto the contents of the pan (chloride of calcium)
an equivalent quantity of strong vitriol. The reaction is Ca Cl₂ + H, SO
Ca SO +2 H ČI. The hydrochloric acid gas disengaged in this reaction we
convey as above said to a condenser where it is converted into acid of suitable
strength say 25° T which we use in the ordinary well known way for the manu-
facture of chlorine. The sulphate of lime we roast at the proper temperature to
convert it into plaster of paris.
=

page_text: 5th The carbonate of ammonia produced by (3) we disengage and mix or dissolve
in strong brine in equivalent proportion we then pass into that solution another
molecule of carbonic acid gas. When we say another molecule of carbonic acid
gas we mean such a quantity of gas as will with the carbonic acid already present
in the carbonate of ammonia added form with the salt in the brine bi-carbonate of
soda in the solid state thus:-(NH₁), CO, +H₂ 0+CO₂+2 Na Cl=2 Na H CO, +
2 NH, Cl. From the above equation it will be noted that there is formed
bi carbonate of soda and a solution of chloride of ammonia ready to be again
subjected to a fresh series of operations similar to those already described.
By using the carbonate of ammonia in this way we save the expense and trouble
of generating and pumping one half the total carbonic acid needed for the produc-
tion of carbonate of soda.
It will be evident (vide head 2) that in place of the carbonate of lime we use to
re act on the chloride of ammonia to produce carbonate of ammonia we may use
the carbonates of barium magnesia or strontia as considered expedient. If magnesia
be used the residue left in the pan after the sublimation will consist of chloride of
magnesia and this salt after decomposition with vitriol will yield the soluble
sulphate of magnesia which may be dissolved in water and crystallized therefrom
to render it marketable, Barium or strontium carbonate used for the same reaction
will leave residues consisting respectively of baric chloride or of strontic chloride
and when this is the case we adopt a slightly different manner of dealing with
these residues. In place of running vitriol on the chloride as it remains in the
sublimation pan we detach it and dissolve it in a suitable amount of hot water
and filter We then run into the chloride solution in suitable tanks an equivalent
quantity of vitriol so as to yield a precipitate of the insoluble sulphate of barium
or strontium and a supernatant solution of hydrochloric acid. Sulphate of barium
prepared in this way is known as blanc fixe and is an article of considerable com-
inercial value while sulphate of strontium thus obtained is in such a fine state
of subdivision as to fit it for many technical applications.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that what
we claim is :
First. In the manufacture of soda by the soda ammonia process, boiling the
solution of chloride of ammonia, mixing the said chloride of ammonia with
carbonate of lime, heating the said mixture and treating the residue with sulphuric
acid substantially in the manner and for the purpose setforth.
Second. In the manufacture of soda by the ammonia soda process, the elimina-
tion of chlorine from the chloride of ammonia by admixture therewith of carbonate
of lime, applying heat to the mixture and treating the residue with sulphuric acid
substantially as setforth.
Third. In the manufacture of soda by the ammonia soda process the treatment
setforth under the five heads herein.
Fourth. In the manufacture of soda by the ammonia process the use of
carbonates of barium strontium or magnesium in place of carbonate of lime, and
the treatment of the residual products therefrom substantially as herein setforth.
Dated the 20th day of November 1884.
J. T. KING,
Per J. Richman,
Agent for the Applicants.