An Improvement in the Manufacture of Bi-carbonate of Soda and Soda-ash.
Year: 1892

page_text: Date of Application, 8th Dec., 1892
Complete Specification Left, 8th Sept., 1893-Accepted, 21st Oct., 1893
PROVISIONAL SPECIFICATION.
An Improvement in the Manufacture of Bi-carbonate of Soda
and Soda-ash.
We, FREDERICK HERBERT GOSSAGE, of Widnes, in the County of Lancaster,
Soap Manufacturer, and JOSEPH WILLIAMSON, also of Widnes, aforesaid,
Chemist, do hereby declare the nature of this invention to be as follows:-
This invention has reference to the manufacture of bi-carbonate of soda, and
soda-ash, from sulphide of sodium, the sulphide of sodium being produced from its
sulphate by heating said sulphate in a furnace in conjunction with alkali waste, or
sulphide of calcium, or their equivalent, or other substance, and carbonaceous
matter.
Heretofore it has not been found possible to produce bi-carbonate of soda from
crude sulphide of sodium alone in such a condition or form as to be readily
separable from the solution used, and so that it can be converted into soda ash by
heat, in the usual way; and in processes at present practised, the sulphide of
sodium is produced from sulphate of soda by heating it in conjunction with sodium
chloride (common salt) and carbonaceous matter, then lixiviating out the sulphide
of sodium, and then in conjunction with sodium chloride (brine) which is added to
it; treating it with carbonic acid gas. We have discovered that bi-carbonate of
soda of a crystalline structure which may be readily separated from its solution
can be, and is according to this invention, obtained from sulphide of sodium by
passing carbonic acid gas through a solution of said sulphide, and without the
addition to or admixture of brine or any extraneous matters with said sulphide of
sodium solution, that is to say, according to our invention, the sulphide of sodium
solution, without the addition of brine or any extraneous matter or substance, is
treated with carbonic acid gas (namely, the carbonic acid being caused to pass
through the sulphide of sodium solution) the solution of sulphide of sodium being
kept within certain limits of strength and temperature.
The process therefore, according to this invention, consists in taking crude
sulphide of sodium, produced as hereinbefore specified (or by other methods) and
lixiviating same, and introducing the solution of the sulphide of sodium (say at
about 1150 specific gravity) into an absorber or other suitable apparatus, and then
passing carbonic acid through same. The first effect of this treatment is to
precipitate the silica, alumina, and iron, and this we filter from the solution. We
then return the solution to the absorber or other apparatus, or another absorber or
apparatus, and treat it again with carbonic acid, whereby bi-carbonate of soda is
precipitated and sulphuretted hydrogen evolved. The limit to which the solution
is reduced is about 3 or 4 per cent. of soda in solution, and we separate the
bi-carbonate from it when this limit (or higher limit) is reached. The temperature
should be fairly cool. The effect of this treatment is that bi-carbonate of a
crystalline structure is thrown down. In this form it may be readily separated
from the solution by a hydro-extractor, or other means.
To render the bi-carbonate pure it is washed with water, whereby any traces of
sulphate or chloride of soda which may be present, are removed, leaving pure
bi-carbonate. Soda ash of high degree of strength and purity is produced from
this bi-carbonate by calcination.
The solution separated from the bi-carbonate with the washings above referred
to, may be used for the purpose of lixiviating a further quantity of sulphide of
sodium

page_text: The sulphuretted hydrogen evolved may be used for the production of sulphur
by any known means."
Dated this 7th day of December 1892.
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicants' Patent Agents.
COMPLETE SPECIFICATION.
An Improvement in the Manufacture of Bi-carbonate of Soda
and Soda-ash.
We, FREDERICK HERBERT GOSSAGE, of Widnes, in the County of Lancaster,
Soap Manufacturer, and JOSEPH WILLIAMSON, also of Widnes, aforesaid,
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 :-
This invention has reference to the manufacture of bi-carbonate of soda, and
soda-ash, from sulphide of sodium, the sulphide of sodium being produced from its
sulphate by heating said sulphate in a furnace in conjunction with alkali waste, or
sulphide of calcium, and carbonaceous matter.
Heretofore it has not been found possible to produce bi-carbonate of soda from
crude sulphide of sodium solution alone, in such a condition or form, as to be
readily separable from the solution used, and so that it can be converted into soda
ash by heat, in the usual way. We have discovered that bi-carbonate of soda of
a crystalline structure which may be readily separated from its solution can be
and is according to this invention, obtained from sulphide of sodium by passing
carbonic acid gas through a solution of said sulphide, and without the addition to
or admixture of brine or any extraneous matters with said sulphide of sodium
solution; that is to say, according to our invention, the sulphide of sodium solution,
without the addition of brine or any extraneous matter or substance, is treated
with carbonic acid gas (namely, the carbonic acid being caused to pass through the
sulphide of sodium solution), the solution of sulphide of sodium being kept within
certain limits of strength and temperature.
The process therefore according to this invention consists in taking crude sulphide
of sodium produced as hereinbefore specified, (or by other methods), and lixiviating
same and introducing the solution of sulphide of sodium at about 1.150 to 1.20
specific gravity (preferably the latter)-that is about 12 to 13 per cent. of soda in
solution into a suitable apparatus, and then passing carbonic acid gas through the
solution. This is carried on for some hours, the effect being the precipitation of
the silica, alumina, and iron, in the solution. As soon as signs of precipitation of
bi-carbonate of soda appear, we stop the process, and filter off from it the
precipitated matters. We then return the solution to the apparatus, or convey it
to another apparatus, and again treat it with carbonic acid gas, whereby
bi-carbonate of soda is precipitated and sulphuretted hydrogen evolved; this is
carried on until only about 3 or 4 per cent. of soda remains in solution, when it is
stopped, this being the limit to which the solution should be reduced for efficient
and proper working: we separate the bi-carbonate from the solution when this
limit (or a higher limit) is reached.
The temperature at which the process should be conducted is a fairly cool one,
say about 80° to 90° Fahr.
The effect of this treatment is that bi-carbonate of soda of a crystalline structure
is thrown down, and in this form it may be readily separated from the solution by
a hydro-extractor, a vacuum filter, or other means.
As regards the strengths of the solution of sulphide of sodium at which the
process of reduction thereof commences, we prefer that of 1.20 specific gravity, as we
find that the bi-carbonate of soda produced when employing it, is of a denser and

page_text: heavier or more crystalline nature, and that it gives also when converted to soda-
ash, an ash of greater density.
To render the bi-carbonate pure it is washed with water, whereby any traces
of sulphate or chloride of sodium which may be present, are removed, leaving pure
bi-carbonate. Soda ash of a high degree of strength and purity is produced from
this bi-carbonate by calcination.
The solution separated from the bi-carbonate with the washings above referred
to, may be used for the purpose of lixiviating a further quantity of sulphide of
sodium.
The sulphuretted hydrogen evolved may be used for the production of sulphur
by any known means.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
:-
The herein described improvement in the manufacture of bi-carbonate of soda
and soda ash from sulphide of sodium, consisting in submitting a solution of such
sulphide of sodium to the action of carbonic acid gas without the addition or
admixture of brine or any extraneous matters, the solution being kept within limits
of strength and temperature as specified.
Dated this 7th day of September 1893.
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicants' Patent Agents.