Year: 1887

page_text: Date of Application, 27th May, 1887
Complete Left, 27th Mar., 1888
Complete Accepted, 4th May, 1888
We, CARL FRIEDRICH CLAUS, of Merton Road, Wimbledon, in the county of
Surrey, Chemist, and HENRY LIVINGSTONE SULMAN and EDWARD ELHANAN BERRY,
both of 76 George Street, Euston Road in the county of Middlesex, Chemists do
hereby declare the nature of this invention to be as follows:-
Our improvements consist in the substitution of solid sodium chloride for the brine
usually employed in the manufacture of soda, by the ammonia soda process; that is
our process consists in making soda by decomposing solid sodium chloride by means
of a solution of ammonium bicarbonate.
We employ a number of vessels of suitable shape, which are charged with sodium
chloride, preferably common salt in a state of fine subdivision, either as ground rock
salt or in the crystalline form as obtained by the evaporation of brine.
We allow a saturated solution of ammonium bicarbonate-which we prefer to
surcharge with carbonic acid gas so as to produce a pressure, say, of five to ten
pounds per square inch in the vessels to flow from one vessel to another throughout
the entire series in a slow but continuous stream. We prefer to construct the vessels,
which may be fitted with agitators if desired, with a filtering surface on the bottom
of each so that only clear liquor can leave a vessel, the whole of the solid matter
being left behind in it. The connections between the vessels are made by means of
pipes which enable the liquor to circulate as above described.
We use an amount of ammonium bicarbonate solution very largely in excess of the
quantity which would be required to decompose the sodium chloride in the first one,
two, or more vessels in the series, so that after complete decomposition has taken
place the final portion of liquor, which passes through the vessel is as free from
chlorides as is practically possible. By the action of the ammonium bicarbonate
solution, decomposition takes place in the vessels, the sodium chloride being converted
into sodium bicarbonate. The mother liquor containing the excess of ammonium
bicarbonate, together with the ammonium chloride resulting from the decomposition
of the sodium chloride, then passes into the next vessel, and so on throughout the
entire series. When the liquor leaves the last vessel, the amount of ammonium

page_text: bicarbonate in it will have been reduced to a minimum and the solution will chiefly
contain ammonium chloride and sodium chloride, together with a small quantity of
ammonium bicarbonate.
After the stream of ammonium bicarbonate solution has passed for some time
through the first vessel this will be found to contain solid granular sodium bicarbonate,
together with the excess of ammonium bicarbonate solution. When this point has
been reached, we force a current of air or carbonic acid gas into the vessel, displacing
the liquor by driving it through the filter bottom into the next vessel. By means of
suitable valves the first vessel is then disconnected from the series and the remainder
of the ammonium bicarbonate is removed by steam, or by any other suitable method,
either in the same vessel or in a separate one. The ammonia and the carbonic acid
which are thus expelled are collected in any convenient apparatus.
The ammonium bicarbonate solution is run direct into the second vessel which has
now become the first of the series, while the previous vessel after being emptied is
recharged with fresh sodium chloride and becomes the last. This mode of working
is carried on indefinitely; each vessel thus becoming in its turn, first, last, and
intermediate in the series.
The sodium chloride may be recovered from the mother liquor obtained from the
last vessel in the series by treating it with ammonium bicarbonate solution and
separating the precipitated sodium bicarbonate as ordinarily practised when solutions
only are used in the process, but we prefer to use solid ammonium bicarbonate in a
state of fine subdivision. The final mother liquor from both of these operations is
also treated with lime for the recovery of the ammonia in the usual manner.

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Soda by the Ammonia Soda
Process.
We, CARL FRIEDRICH CLAUS, HENRY LIVINGSTONE SULMAN and EDWARD
ELHANAN BERRY, all of 8 Victoria Chambers in the city of Westminster, consulting
chemists 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 :-
Our improvements consist in decomposing solid sodium chloride by means of a
solution of ammonium bicarbonate whereby sodium bicarbonate and ammonium
chloride are formed. The resulting liquor is run off, and any ammonium chloride
left adhering to the sodium bicarbonate is removed by washing the latter with a fresh
solution of ammonium bicarbonate or sesquicarbonate, this being finally separated
from the sodium bicarbonate by the application of heat when the ammonium carbonates
are driven off and the sodium carbonate remains behind in the form of the nono-
carbonate.
We employ a series of closed vessels of suitable shape which are charged with
sodium chloride, preferably common salt in a state of fine subdivision either as
ground rock-salt, or in the crystalline form as obtained by the evaporation of brine.
We prefer to construct the vessels-which should be fitted with effective means
for agitating the contents-with a filtering surface on some part of them so that
clear liquor only can be made to leave a vessel, the whole of the solid matter
being left behind in it. The connections between the vessels are made with pipes
which enable the liquor to pass from one vessel to another.
After the vessels have been partially filled with sodium chloride we run into
the first of them ammonium carbonate solution, and we prefer to produce the
ammonium bicarbonate solution in the vessel itself by pumping into the latter a
solution of ammonium carbonate containing less carbonic acid than is necessary to
form ammonium bicarbonate, and we take care that the water of this solution is
sufficient but not greatly in excess of the quantity required to keep in solution
the ammonium chloride formed subsequently in the process. The ammonium
bicarbonate is then formed by forcing carbonic acid gas into the solution.
As long as there is any undecomposed sodium chloride present the carbonic
acid rapidly passes into combination with the sodium, forming sodium bicarbonate,
but as soon as the decomposition of the sodium chloride is complete the action of
the carbonic acid on the ammonium sesquicarbonate takes place very slowly, and
the ammonium carbonate leaves the vessel still largely as sesquicarbonate although
in the presence of free carbonic acid. In fact, the ammonium sesquicarbonate
acts as a rapid carrier of carbonic acid to the sodium only as long as any sodium
chloride is present.

page_text: A portion or the whole of the required ammonium carbonate may, however,
without detriment be introduced into the vessels as ready formed bicarbonate but
on account of its lesser solubility, in order not to materially exceed the quantity
of water required to keep the ammonium chloride in solution a portion of the
bicarbonate in this case must necessarily be introduced in a concentrated state,
preferably as a semi-crystalline mass.
The carbonic acid is forced into the first vessel by means of any suitable pump
under a pressure of say 15 pounds per square inch, or thereabouts, and is maintained
at that pressure. We prefer to use comparatively pure carbonic acid gas such as is
obtained by the decomposition by heat of the sesquicarbonate and bicarbonate of
the alkalies. Each vessel in the series is connected with the carbonic acid reservoir
so that the gas can be pumped direct into any one of them, as may be desired;
and, further, each vessel is so constructed that it can receive a direct supply of
ammonium carbonate.
We use an amount of ammonium bicarbonate largely in excess of the amount
which would be required to decompose the sodium chloride in the first vessel in
the series so that after complete decomposition has taken place the final portion
of liquor which is passed through is free from chlorides. Thus, when the
ammonium bicarbonate solution has been allowed to act on the sodium chloride
in the first vessel for sufficient time the vessel will be found to contain solid
sodium bicarbonate of a granular texture, together with the excess of ammonium
bicarbonate and sesquicarbonate, and also the ammonium chlorido, produced by
the reaction, in solution. When this point has been reached we discharge the
mother-liquor by the pressure of the carbonic acid gas through the straining or
filtering surface, either into the next vessel or into an ammonia recovery plant.
Fresh ammonium bicarbonate or sesquicarbonate solution is then run in to wash
the sodium bicarbonate; this solution is subsequently run into the next vessel
and the washing repeated until the sodium bicarbonate is practically free from
chlorides.
The mother liquor consists of a strong solution of ammonium chloride together
with an excess of ammonium carbonate and it may be run into the next vessel
where the excess of ammonium carbonate is acted on by fresh quantities of sodium
chloride and carbonic acid, but we may regulate the amount of ammonium
carbonate added to the first vessel so that after the decomposition of the sodium
chloride has taken place only a slight excess of it remains in the mother-liquor,
which is run direct into the ammonia recovery plant and treated for the recovery
of the ammonia and carbonic acid. In either case, however, the washings, which
consist of solutions of ammonium bicarbonate and sesquicarbonate, together with
a little ammonium chloride, are passed into the second vessel and used for the
decomposition of the sodium chloride therein.
As soon
as the sodium bicarbonate in the first vessel has been sufficiently
washed, by means of suitable valves the vessel is disconnected from the series
and the remainder of the ammonium bicarbonate and sesquicarbonate driven out by
steam or by any other suitable method, either in the same vessel or in a separate one.
The vapours of ammonium carbonate which are thus expelled are collected in any
suitable condensing apparatus, such as a coke tower, whilst the free carbonic acid gas
is collected in a gas-holder and used over again.
Any ammonium carbonate required above that already added in the washings from
the first vessel is then run direct into the second vessel which has now become the
first of the series, whilst the previous vessel after being emptied is recharged with
fresh sodium chloride and becomes the last in the series. This mode of working is
carried on indefinitely each vessel thus becoming in its turn first, last, and inter-
mediate in the series.
The mother liquors from these operations, consisting of ammonium chloride, together
with some excess of ammonium bicarbonate or sesquicarbonate, is treated for the
recovery of the ammonia and carbonic acid in the usual manner.
It is preferred to use in this process purified finely grained sodium chloride but if

page_text: ground rock-salt be used the sodium carbonate solution obtained after distilling off
the ammonium carbonate may be purified by simply allowing all impurities to settle
out of it. The solution may then be crystallised or boiled down to dryness to
produce soda-ash.
Having now particularly described and ascertained the nature of our Invention,
and in what manner the same is to be performed, we declare that what we claim is :
1. In the process described, decomposing solid sodium chloride by means of
solutions of ammonium bicarbonate or of sesquicarbonate in the presence of carbonic
acid gas under pressure and producing sodium carbonate, substantially as described.
2. In the process described, washing the sodium bicarbonate therein formed by
means of further quantities of solutions of ammonium bicarbonate or sesquicarbonate,
substantially as described.
3. In the process described, employing a series of decomposing vessels charged with
solid sodium chloride and in which the liquor from the first vessel is passed into the
second, and so on in rotation throughout the series, substantially as described.
4. In the process described, forming the solutions of ammonium bicarbonate in the
decomposing vessels themselves by the action of carbonic acid on solutions of more
basic ammonium carbonates, substantially as described.
5. In the process described, separating by distillation sodium bicarbonate from the
ammonium bicarbonate and sesquicarbonate used for washing it and converting the
sodium bicarbonate into the monocarbonate at the same time, substantially as
described.
6. In the process described, recovering as ammonium bicarbonate or sesquicarbonate
(in condensers or similar apparatus) the ammonia set free by the process referred to
in the preceding claim, and collecting in gas-holders for re-use the carbonic acid
liberated at the same time, substantially as described.
7. In the process described, the cycle of operations forming a process for producing
sodium carbonate, substantially as described.