Improvements in and connected with the Production of Caustic Soda from Sulphide of Sodium or Sulphydrate of Sodium, partly applicable also to the Manufacture of Bi-carbonate of Soda and Soda Ash.
Year: 1892

page_text: Date of Application, 22nd Dec., 1892
Complete Specification Left, 22nd Sept., 1893-Accepted, 28th Oct., 1893
PROVISIONAL SPECIFICATION.
Improvements in and connected with the Production of Caustic Soda
from Sulphide of Sodium or Sulphydrate of Sodium, partly
applicable also to 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 mainly to the production or manufacture of caustic
soda from sulphide of sodium or sulphydrate of sodium, or solutions thereof, and to
the production of sulphuretted hydrogen; and it has reference also in part to the
production or manufacture of bi-carbonate of soda and soda ash. And the method
of such production, to which it bas special reference, is that in which carbonic acid
gas is used to decompose the said solution.
In the decomposition of a solution of sulphide of sodium or sulphydrate of
sodium, wherein carbonic acid gas is employed for such decomposition, as at present
practised, the soda is precipitated from the solution as bi-carbonate of soda in a
crystalline form, and from this bi-carbonate of soda, caustic soda is produced by
first converting it to mono-carbonate, and then to caustic: while weak sulphuretted
hydrogen is given off.
Now according to this invention we produce caustic soda from the solution of the
sulphide of sodium or sulphydrate of sodium, by first obtaining or making mono-
carbonate of soda in solution therefrom, direct, which is then causticised in the
usual manner for the production of caustic soda. We also at the same time
produce sulphuretted hydrogen of comparatively great strength or richness: or in
other words, the gases evolved are relatively rich in sulphuretted hydrogen, and
relatively more valuable for the manufacture or obtainment of sulphur or vitriol
therefrom; which may be done in any known way. In some cases, where desired,
the solution of carbonate of soda may, subsequently to its production from the
sulphide or sulphydrate of sodium solution, be treated as hereafter described for
the manufacture of bi-carbonate of soda, and soda ash therefrom.
We have discovered that by treating (and our invention is comprehended in the
treating of) sulphide of sodium or sulphydrate of sodium solution at or about a
boiling temperature, with carbonic acid gas; that is, by passing the said gas
through the hot solution, it is decomposed, and the soda converted into carbonate
of soda and retained in solution, whilst the gases given off are relatively very rich
(approximating twice as rich as those given off in the process heretofore practised)
in sulphuretted hydrogen.
any
In operating according to this invention, we place the solution of sulphide of
sodium or sulphydrate of sodium, or mixture thereof, in a suitable vessel, raise it to
boiling point, or about boiling point, and then pass carbonic acid gas through it;
the effect of which is the direct conversion of the sulphide or sulphydrate of sodium
solution to a solution of carbonate of soda; which, by causticising in suitable
way, is converted into caustic soda. If it is desired in some cases to produce
bi-carbonate of soda and soda ash therefrom, the solution of carbonate of soda
would be subsequently treated, and at a low temperature, with carbonic acid gas,
and converted to bi-carbonate of soda in a crystalline form, which can be separated
from its solution; or the bi-carbonate may be produced by other known methods;

page_text: and from this bi-carbonate of soda, soda ash may be produced in any known
suitable way.
Dated this 21st day of December 1892.
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicants' Patent Agents.
COMPLETE SPECIFICATION.
Improvements in and connected with the Production of Caustic Soda
from Sulphide of Sodium or Sulohydrate of Sodium, partly
applicable also to 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 :-
The invention has reference mainly to the production or manufacture of caustic
soda from sulphide of sodium or sulphydrate of sodium, or from solutions thereof,
and to the production of sulphuretted hydrogen; and it has reference also in part
to the production or manufacture of bi-carbonate of soda and soda ash. And the
method of such production, to which it has special reference, is that in which
carbonic acid gas is used to decompose the said solution.
In the decomposition of a solution of sulphide of sodium or sulphydrate of sodium,
wherein carbonic acid gas is employed for such decomposition, as at present
practised, the soda is precipitated from the solution as bi-carbonate of soda in a
crystalline form, and from this bi-carbonate of soda, caustic soda is produced by
first converting it to mono-carbonate, and then to caustic.
Now according to this invention we produce caustic soda from the solution of the
sulphide of sodium or sulphydrate of sodium, or both in combination, by first
obtaining or making mono-carbonate of soda in solution therefrom, direct, which is
then causticised in the usual manner for the production of caustic soda. We also
at the same time produce sulphuretted hydrogen of comparatively great strength
or richness or in other words, the gases evolved are relatively rich in sulphuretted
hydrogen, and relatively more valuable for the manufacture or obtainment of
sulphur or sulphuric acid therefrom, which may be done in any known way. In
some cases, where desired, the solution of carbonate of soda may, subsequently to
its production from the sulphide or sulphydrate of sodium solution, be treated as
hereafter described for the manufacture of bi-carbonate of soda, and soda ash
therefrom.
We have discovered that by treating (and our invention is comprehended in the
treating of) sulphide of sodium or sulphydrate of sodium solution at or about a
boiling temperature, with carbonic acid gas; that is, by passing the said gas
through the hot or boiling solution, it is decomposed, and the soda converted into a
solution of mono-carbonate mixed with a small proportion of bi-carbonate of soda,
whilst the gases given off are relatively very rich in sulphuretted hydrogen.
In operating according to this invention, we first treat the solution of sulphide or
sulphydrate of sodium with carbonic acid gas in a cold or cool state, until the
silica, iron, and alumina, are precipitated, and we separate the precipitate by
filtration. We then run the filtered solution into a suitable vessel, raise it to the
boiling point, and pass carbonic acid gas through it; the effect of which is, the
direct conversion of the sulphide or sulphydrate of sodium solution into a solution
of mono-carbonate of soda; which, by.causticising in any suitable way, is converted
into caustic soda. If it is desired in some cases to produce bi-carbonate of soda

page_text: and soda ash therefrom, the solution of carbonate of soda would be subsequently
treated, at a low temperature, with carbonic acid gas-say as is at present
practised and converted to bi-carbonate of soda in a crystalline form, which can
be readily separated from its solution; and from this bi-carbonate of soda, soda-ash
may be produced in any known suitable way.
One arrangement of apparatus by which the solution of sulphide of sodium or
sulphydrate (or a mixture thereof) is converted into a solution of mono-carbonate
of soda (which however our invention is not restricted to in the carrying of it out)
consists of three vessels A B and C. In the first vessel, A, we treat the cold
solution with carbonic acid gas for the precipitation of the silica, alumina, and
iron, which we filter from the solution from this vessel. We then convey it into
vessel B where it is treated with the mixed gases-carbonic acid gas and
When the solution in vessel B is
sulphuretted hydrogen-coming from vessel C.
on the point of depositing solid bi-carbonate of soda it is run into vessel C where it
is boiled and treated with carbonic acid gas (say from a lime kiln), the result
being the formation of mono-carbonate of soda together with a small amount of
bi-carbonate of soda in solution, while the excess of carbonic acid gas and other
gases pass into vessel B, where the carbonic acid gas is absorbed and strong
sulphuretted hydrogen given off. When the solution in vessel C is free from
sulphide of sodium, that is all converted to carbonate of soda, it is run off and is
ready for being converted into caustic soda, which is done in any known suitable
way; or, into bi-carbonate of soda, or soda ash, as herein described. The vessel C
is then refilled from vessel B, and B from vessel A, and so on continuously. All
these vessels may be of any known suitable kinds.
By applying this mode of treatment in the carrying out of the invention,
economy as regards consumption of carbonic acid, and steam (or fuel) for heating
the solution is effected.
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 :-
1. (a.) The herein described improvement in the production of caustic soda from
sulphide of sodium sulphydrate of sodium, that is to say, treating a solution of
or
and
or
and
the said sulphide of sodium sulphydrate of sodium to the action of carbonic
acid gas whilst at a boiling temperature, by which it is converted to mono-carbonate
of soda in solution, and subsequently causticising said mono-carbonate of soda in
solution, whereby said solution of mono-carbonate of soda is directly converted to
caustic soda.
(b.) Also, the herein described improvement in the manufacture of bi-carbonate
of soda, and soda ash, from sulphide of sodium sulphydrate of sodium, that is
or
and
and
or sulphydrate of sodium
to say, treating a solution of the said sulphide of sodium
to the action of carbonic acid gas whilst at a boiling temperature, by which it is
converted to mono-carbonate of soda in solution, and subsequently treating such
solution at a low temperature with carbonic acid gas, whereby it is converted to
bi-carbonate of soda in a crystalline form which is easily separated from its
solution; or, to soda ash by driving off one atom of carbonic acid from said
bi-carbonate of soda so produced, in any known suitable way.
or
2. In or for the manufacture of caustic soda from sulphide of sodium and
sulphydrate of sodium; or in the manufacture of bi-carbonate of soda; or soda
ash; the production, substantially as and for the purposes set forth, of a solution

page_text: of mono-carbonate of soda in two stages, by treating said solution of sulphide of
sodium sulphydrate of sodium in a suitable vessel (whilst cold or cool) to the
or
and
action of the gases leaving the apparatus wherein the completion of the production
of said solution of mono-carbonate of soda is effected, and subsequently treating the
solution so operated upon to the action of carbonic acid gas in a suitable vessel
whilst at a boiling temperature.
Dated this 21st day of September 1893
.CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicants' Patent Agents.