Process for Obtaining Hydrosulphide of Sodium, or Sulphate of Sodium, and Sulphuretted Hydrogen and Sulphate of Calcium from Sulphide of Calcium or Soda Residues, and Mono-sodium Sulphate or Bisulphate of Soda.
Year: 1896

page_text: Date of Application, 10th Jan., 18'6
Complete Specification Left, 10th Sept.. 1896-Accepted, 10th Oct., 1896
PROVISIONAL SPECIFICATION.
A Process for Obtaining Hydrosulphide of Sodium, or Sulphate of
Sodium, and Sulphuretted Hydrogen and Sulphate of Calcium
from Sulphide of Calcium or Soda Residues, and Mono-sodium
Sulphate or Bisulphate of Soda.
I BENJAMIN WILLCOX, of 47 Lincoln's Inn Fields, in the County of London,
Patent Agent, do hereby declare the nature of this invention (which has been
communicated to me from abroad by the Firm of Chemische Fabrik Griesheim of
Frankfort-on-the-Main in the German Empire) to be as follows:-
It is well known that calcium-sulphide and sodium sulphate may be caused to
re-act so as to form sodium sulphide (or sulphuret) and calcium sulphate. There
is, however, this difficulty in regard to the said reaction, that it can only take place
at a comparatively high temperature, and not until a pressure of five atmospheres is
reached.
My foreign correspondents have found that calcium sulphide is capable of
entering into reaction at the ordinary temperature and without the employment of
pressure, if, instead of di-sodium sulphate, mono-sodium sulphate be used; in which
case, however, the product obtained will not be sulphide of sodium but hydro-
sulphide of sodium.
The reason why, under these circumstances, the agents named will react more
readily is, that the sulphuretted hydrogen, which forms at the very outset,
renders the calcium sulphide soluble, in the form of hydrosulphide of calcium
and thereby makes it capable of reaction, as is demonstrated by the following
equations:-
process takes the course expressed by the following equation
(d) CaS+ NaHSO, NaHS + CaSO.
=
In addition to the important technical advantage which this process derives from
the fact that it can be performed without any extra supply of heat from outside and
at the normal temperature, it presents considerable superiority over the old method
from the point of view of economy, inasmuch as it enables two bye-products, which
are collected wherever the chemical industry is carried on upon a large scale, but
which, in themselves, are of little or no value,-viz. :-the soda residues containing
calcium sulphide and the waste matter that forms in the course of the nitric acid
manufacture and is known as "bi-sulphate," to be turned to account and utilized
by mutual reaction. This economical superiority will readily be realized when it
is remembered. that the market price of the bi-sulphate does not amount to more
than one third of the market price of the sulphate.
The hydrosulphide of sodium, which forms in the course of the improved process,
may either be converted into sulphide of sodium, by the well known methods, or
be employed directly for purposes of reduction, similarly to sulphide of sodium.

page_text: In some cases, owing to the hydrogen it contains, its action is more powerful than
that of the sodium sulphide.
Where the industrial or commercial "bi-sulphate" employed happens not to
consist of pure mono-sodium sulphate, but to contain, besides, a surplus of
sulphuric acid, there will form, in addition to the hydrosulphide of sodium, a
proportionate amount of sulphuretted hydrogen, according to the following
equation:-
(e) CaS+H₂SO₁ = CaSO, + H,S.
The sulphuretted hydrogen, however, remains in the solution of hydrosulphide of
sodium, and may also be utilised as a reducing medium; though, if preferred, it
may be eliminated from the solution by the action of heat and then worked into
sulphur by the well known methods.
If it be desired to extract the whole of the sulphur of the calcium sulphide,
either in the form of sulphuretted hydrogen, or as free sulphur, this result may
be obtained by doubling the quantity of sulphate of mono-sodium originally
employed; when the portion added in thus doubling the quantity will act upon the
hydrosulphide of sodium formed in the first instance, in the manner expressed by
the following equation:-
(9) CaS+ 2 NaHSO4 = CaSO, + Na,SO, + H,S.
By such means the further considerable advantage is realized, that, by a simple
process readily performed on a manufacturing scale, the "bisulphate," possessing
but little value, may be converted into valuable sulphate; a result which has been
repeatedly suggested as desirable, but none of the suggestions made have proved
hitherto commercially available.
By the improved method herein described, not only is the whole of the sulphate
of sodium contained in the "bi-sulphate," extracted, but the sulphuric acid
absorbed by, or incorporated in such bi-sulphate (and of which there may be even a
certain amount in excess) may be taken advantage of.
This transformation of the residues from soda into sulphuretted hydrogen and, if
required, into sulphur, possesses very material technical advantages over the method
involving the employment of carbonic acid and pressure, since it enables extremely
simple apparatus to be used in its performance; while it is more economical than
the other method because of the insignificant value of the sulphuric acid which the
bisulphate " carries within it; it being necessary, in the old process referred to,
to provide pure carbonic acid, free from air, which is, of course, expensive.
The improved process is carried out as follows:-
The calcium sulphide, or the soda mud, is stirred in large closed iron chambers,
or receivers, by means of suitable stirring mechanism, a small quantity of water
being added. Then a concentrated solution of bi-sulphate is gradually admitted.
The reaction will then, at once, set in, heat being at the same time evolved.
The proportions in which the mouo-sodium sulphate, or bi-sulphate should be
used are determined by the equations given above.
When the reaction is completed, the calcium sulphate, in a crystalline form, is
separated from the lye which may be done by means of a press or of a suction
device. The lye may then be utilized, either directly, for purposes of
reduction or the like, or by being "steamed" in a closed vessel from which air
is excluded, preferably in vacuo, it being thus converted either into hydro-
sulphide of sodium, or into sulphide of sodium, which may be done by well
known methods.
In the second case the sulphate of sodium obtained will for the most part

page_text: crystallize out of the lye, as it cools; while that which remains behind in the
mother lye, is separated by continued steaming or evaporation.
The sulphuretted hydrogen thus obtained is then carried off through a pipe with
which the stirring mechanism is provided.
The calcium sulphate remaining in each case constitutes a crystalline uniformly
fine-grained mass, which may be subsequently utilised for agricultural purposes in
the condition of sandy powder tinged a grey hue by the coke residues.
An important feature of this invention is due to the fact that it enables the
extremely objectionable residual matters collected in the course of soda manu-
facture by the Le Blane process, to be worked into serviceable products and thus
rendered harmless, as soon as they form.
Dated this 10th day of January 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.
A Process for Obtaining Hydrosulphide of Sodium, or Sulphate of
Sodium, and Sulphuretted Hydrogen and Sulphate of Calcium
from Sulphide of Calcium or Soda Residues, and Mono-sodium
Sulphate or Bisulphate of Soda.
I, BENJAMIN WILLCOX of 47 Lincoln's Inn Fields in the County of London,
Patent Agent do hereby declare the nature of this invention (which has been
communicated to me from abroad by the Firm of Chemische Fabrik Griesheim of
Frankfort-on-the-Main in the German Empire) and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:
It is well known that calcium-sulphide and sodium sulphate may be caused to
react so as to form sodium sulphide (or sulphuret) and calcium sulphate. There
is, however, this difficulty in regard to the said reaction, that it can only take
place at a comparatively high temperature and not until a pressure of five
atmospheres is reached.
My foreign correspondents have found that calcium sulphide is capable of
entering into reaction at the ordinary temperature and without the employment of
pressure, if, mono-sodium sulphate be used'; instead of disodium sulphate, in which
case however the product obtained will not be sulphide of sodium, but hydro-
sulphide of sodium.
'T'he reason that under these circumstances, the agents named react more readily
is, that the sulphuretted hydrogen, which forms at the very outset, renders the
calcium sulphide soluble, in the form of hydro-sulphide of calcium, and thereby
makes it capable of reaction, as is demonstrated by the following equations:
In addition to the important technical advantage which this process possesses
from the fact that it cau be performed at the normal temperature and without any

page_text: extra supply of heat from outside, it presents considerable superiority over the
old method on the ground of economy inasmuch as it enables two bye products
which are collected wherever the chemical industry is carried on upon a large
scale, but which, in themselves, are of little or no value-viz: the soda residues
containing calcium sulphide and the waste matter that forms in the course of the
nitric acid manufacture and is known as "bi-sulphate" to be turned to account and
utilized by mutual reaction. This economy will readily be realized from the fact
that the market price of the bi-sulphate does not amount to more than one third
of the market price of the sulphate.
The hydrosulphide of sodium, which forms in the course of the improved process,
may either be converted into sulphide of sodium by the well known inethods, or he
employed directly for purposes of reduction similarly to sulphide of sodium. In
some cases owing to the hydrogen it contains its action is more powerful than that
of the sodium sulphide.
Where the industrial or commercial bisulphate employed happens not to consist
of pure mono-sodium sulphate but to contain sulphuric acid there will form in
addition to the hydrosulphide of sodium a proportionate amount of sulphuretted
hydrogen according to the following equation:
The sulphuretted hydrogen however, remains in the solution of hydrosulphide
of sodium and may also be utilized as a reducing medium; though if preferred,
it may be eliminated from the solution by the action of heat, and be then worked
into sulphur by the well known methods.
If it be desired to extract the whole of the sulphur of the calcium sulphide,
either in the form of sulphuretted hydrogen, or as free sulphur, this result may be
obtained by doubling the quantity of mono-sodium sulphate originally employed;
when the portion added in thus doubling the quantity will act upon the hydro-
sulphide of sodium formed in the first instance, in the manner expressed by the
following equation:
(9) CaS+2 NaHSO: CaSO + Na,SO + H₂S.
By such means there is obtained the further considerable advantage that by a
simple process readily performed on a manufacturing scale, the "bisulphate,"
possessing but little value, may be converted into valuable sulphate; a result
which has been repeatedly suggested as desirable, but none of the suggestions
made have proved hitherto commercially available.
By the improved method herein described not only is the whole of the sulphate
of sodium contained in the bi-sulphate extracted, but the sulphuric acid absorbed
by, or incorporated in such bi-sulphate (and of which there may be even a certain
amount in excess) may be taken advantage of.
This transformation of the residues from soda into sulphuretted hydrogen and,
if required, into sulphur, possesses very material technical advantages over the
method involving the employment of carbonic acid and pressure, since it enables
extremely simple apparatus to be used in its performance; while it is more
economical than the other method because of the insignificant value of the
sulphuric acid which the bisulphate carries within it; it being necessary, in the
old process referred to, to provide pure carbonic acid, free from air, which is, of
course expensive.
The improved process is carried out as follows:
The calcium sulphide, or the soda mud is stirred in large closed iron chambers.

page_text: or receivers, by means of suitable stirring mechanism, a small quantity of water
being added. Then a concentrated solution of bi-sulphate of soda is gradually
admitted. The reaction will then at once set in, heat being at the same time.
evolved.
The proportions in which the mono-sodium sulphate or bi-sulphate should be
used are determined by the equations herein before given.
When the reaction is completed, the calcium sulphate, in a crystalline form is.
separated from the lye which may be done by means of a press, or of a suction
device. The lye may then be utilized, either directly for purposes of reduction or
the like or by being "steamed " in a closed vessel from which air is excluded
preferably in vacuo, it being thus converted either into hydrosulphide of sodium,.
or into sulphide of sodium which may be done by well known methods.
In the second case the sulpbate of sodium obtained will for the most part.
crystallize out of the lye, as it cools; while that which remains behind in the
mother lye is separated by continued steaming or evaporation.
The sulphuretted hydrogen thus obtained can be carried off through a pipe with.
which the stirring mechanism is provided.
The calcium sulphate remaining in each case constitutes a crystalline uniformly
fine-grained mass, or sandy powder (tinged grey by the coke residues) which may
be utilized for agricultural purposes.
An important feature of this invention is due to the fact that it enables the
extremely objectionable residual matters collected in the course of soda manufacture
by the Le Blanc process to be worked into serviceable products and thus rendered
harmless, as soon as they form.
Having now particularly described and ascertained the nature of this inven-.
tion and in what manner the same is to be performed I declare that what I
claim is.-
A process for obtaining hydrosulphide of sodium or sulphate of sodium and
sulphuretted hydrogen and at the same time forming sulphate of calcium consisting
in agitating, or stirring, calcium sulphide; or soda residues, with a solution of mono-
sodium sulphate (or bi-sulphate of soda) such as forms in the course of nitric acid
manufacture; so that (according to the quantity of the said sulphate employed)
either hydrosulphide of sodium, or sulphate of sodium and sulphuretted bydrogen.
will form.
Dated this 10th day of September 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents..