Improvements in the Manufacture of Bicarbonate of Soda.
Year: 1895

page_text: Date of Application, 20th Apr.: 1905
Complete Specification Left, 15th Jan., 1896-Accepted, 15th Feb., 1896
Date of Apprivation
Complete Specification Left, 15th Jan., 1896-Accepted, 15th Feb., 1896
Improvements in the Manufacture of Bicarbonate of Soda.
We JOHN BROCK Director of The United Alkali Co. Ld. and JOSEF
HAWLICZEK Chemist both of G Exchange Buildings Liverpool in the County
of Lancaster do hereby declare the nature, of this invention to be as follows:-
Hitherto commercial bicarbonate of soda has been produced by the addition of
carbonic acid and of water either as such or in form of steam, if necessary, to. soda
ash or soda crystals or to monohydrated carbonate of soda, but these processes do
not yield sufficiently pure bicarbonate of soda. Or the crude bicarbonate, of soda
as obtained in the ammonia soda process was purified and freed from ammonia by
recrystallization. The sparing solubility of bicarbonate of soda in water at the
limited temperature allowable on account of the liability of the solution to partial
decomposition, and the drying of the wet bicarbonate at a comparatively. low
temperature necessitate a large and costly plant and much labour.
According to this invention we employ the substance produced in the ammonia
soda process known as "roaster ash which is the product obtained by treating in
a closed vessel at a temperature not below 130 to 140 degrees Centigrade the crude
bicarbonate so as to eliminate therefrom all the ammonia. or salts of ammonia.
The material resulting from this treatment is similar in composition to sesqui-
carbonate of soda it containing combined water and considerably more carbonic
acid than corresponds to neutral carbonate of soda. Crude sodium bicarbonate
from other sources when similarly treated may also be employed.
A's this "roaster ash" does not absorb carbonic acid unless water be first added
thereto, we add an adequate quantity of water, either in the liquid form or as
steam but we prefer to treat it with steam in a closed vessel whilst continually
agitating the mass as the steam besides hydrating the material. assists in its
disintegration whereas water in the liquid form tends to consolidate the mass and
to render it less suitable for the subsequent absorption of carbonic acid gas.
When the ash has been sufficiently hydrated we treat it with carbonic acid, gas in
a closed vessel whilst continuously agitating the mass. Heat is evolved and the
ash is gradually and completely converted into bicarbonate of soda. Should there
be any excess of water it can be removed by passing a current of carbonic acid gas.
over the warm bicarbonate.
t
We prefer to first hydrate by steam and to subsequently add the carbonic acid
in the same vessel, but both operations may be carried on simultaneously in the
same vessel by employing a suitable mixture of carbonic acid gas and steam.
Dated this 26th day of April 1895.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.

page_text: Improvements in the Manufacture of Bicarbonate of Soda.
We, JOHN BROCK, Director of The United Alkali Company Limited; and JOSEF
HAWLICZEK, Chemist, both of G 11 Exchange Buildings, Liverpool in the County
of Lancaster, do hereby declare the nature of our invention and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement :-
1
T.
Hitherto commercial bicarbonate of soda has been produced by the addition of
carbonic acid and of water either as such, or in the form of steam, if necessary,
to soda-ash, or soda crystals, or to monohydrated carbonate of soda, but these
processes do not yield sufficiently pure bicarbonate of soda. 'Or the crude
bicarbonate of soda, as obtained in the ammonia soda process, was purified and
freed from ammonia by recrystallization. The sparing solubility of bicarbonate of
soda in water at the limited temperature allowable on account of the liability of
the solution to partial decomposition and the drying of the wet bicarbonate at a
comparatively low temperature necessitate a large and costly plant and much
labour.
T
According to this invention we employ the substance produced in the ammonia
soda process known as "roaster ash" which is the product obtained by treating in
a closed vessel, at a temperature not below 130 to 140 degrees Centigrade, the
crude bicarbonate so as to eliminate therefrom all the ammonia, or salts of
ammonia. The material resulting from this treatment is similar in composition to
sesquicarbonate of soda, it contains combined water and considerably more carbonic
acid than corresponds to nentral carbonate of soda. Crude sodium bicarbonate
from other sources when similarly treated, or other substances having a similar
composition, may also be employed:
As this roaster ash" does not absorb carbonic acid unless water be first added
thereto, we add an adequate quantity of water, either in the liquid form, or as
steam, but we prefer to treat it with steam in a closed vessel whilst continually
agitating the mass as the steam besides hydrating the material assists in its
disintegration whereas water, in the liquid form, tends to consolidate the mass
and to render it less suitable for the subsequent absorption of carbonic acid gas.
When the ash has been sufficiently hydrated we treat it with carbonic acid gas in
a closed vessel whilst continuously agitating the mass. Heat is evolved and the
ash is gradually and completely converted into bicarbonate of soda. Should there
be any excess of water it can be removed by passing a current of carbonic acid
gas over the warm bicarbonate.
We prefer to first hydrate by steam, and to subsequently add the carbonic acid
in the same vessel, but both operations may be carried on simultaneously'in the
same vessel by employing a suitable mixture of carbonic acid gas and steam.
The carbonic acid gas may be derived from any source and it may contain inert
gases. It may be obtained from a lime kiln for example, but in that case it must
be well washed and freed from sulphurous acid.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. In the manufacture of bicarbonate of soda, treating "roaster ash," or crude
bicarbonate of soda from which ammonia and salts of ammonia have been removed,
or substances having a similar composition; first with steam, or water, and
afterwards with carbonic acid gas; substantially as hereinbefore described.
2. In the manufacture of bicarbonate of soda, treating "roaster ash," or crude:

page_text: bicarbonate of soda from which ammonia and salts of ammonia have been removed,.
or substances having a similar composition; simultaneously with steam or water
and carbonic acid gas; substantially as hereinbefore described.
Dated this 15th day of January 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents..