Year: 1887

page_text: Date of Application, 9th Aug., 1887
Complete Specification Left, 9th May, 1888
Complete Specification Accepted, 3rd Aug.,
1888
I, JACOB BAYNES THOMPSON, of 130 Queens Road, Peckham, in the County of
Surrey, Chemist, do hereby declare the nature of this Invention, to be as follows :-
-
My invention has for its object, improvements in the mode or method of manu-
facturing soda by the sulphide process, and consists :
First, in the reduction of sodium sulphate to sodium sulphide.
Secondly, in the mode of converting the sodium sulphide into neutral sodium
carbonate, and
Thirdly, in the apparatus by means of which that reaction is effected.
It has been found that when sodium sulphate is deoxidised to sodium sulphide, by
not more than double the theoretic quantity of carbon, if the heat of the furnace be
above bright red, the sulphide is decomposed by the silicic acid of the bricks of the
furnace, thus silicate of soda is formed at the expense of the furnace, or if reduced in
iron it attacks the iron, iron sulphide being formed, that is when the carbon is not
more than one third by weight of the sodium sulphate.
Now, I have found that when the carbon is equal in weight to one half of the
sulphate the resulting sulphide is masked by the excess of carbon and is not then in
a fluid state and does not then attack fire bricks, 1 therefore add to the sodium sulphate
one half its weight of powdered coal, or other form of carbon, the two being intimately
mixed. This mixture is put into a species of reverberatory furnace, which has been
previously heated to 1000° Centigrade (or bright red), and allowed to remain quietly
at about 800° Centigrade or full red, until carbonic oxide ceases to burn on its
surface. When the tongues of flame cease to appear, the sulphate is deoxidised, and
the sulphide may be removed from the furnace, and allowed to cool, but it should be
protected from the air.

page_text: The reverberatory furnace mentioned above should be one that does not admit more
air than is necessary for the thorough oxidation of the fuel in the combustion chamber,
and the carbonic oxide in the reverberator, otherwise the free oxygen will act on the
mixture in the reverberator, which is to be avoided, but if too much free oxygen
should pass in, then that may be corrected by throwing a little powdered coal over
the top of the inixture.
The sodium sulphide, when cold is dissolved out in a suitable tank, and the excess
of carbon allowed to settle, or is otherwise separated. The clear liquor is then run
into an apparatus, which I will call the Carbonator, and which is described hereinafter.
The excess of carbon which has been separated may be used again for reducing more
sulphate.
Now, in order to be enabled to explain the action of the carbonic acid on the sulphide
in the solution, it will be necessary to describe the carbonator, referred to above, in
conjunction with the process effected by it.
This carbonator is in the form of a long tank, with a circular airtight cover, in
which revolves a series of discs on a spindle. Each disc is cut down one one side to
near its centre, and is then twisted into the form of one whorl of a screw, so that
when the whorls are fixed on the spindle or shaft they form a continuous screw, the
whorls being fixed to follow each other in that form; or they may be fixed discon-
tinuously, that each whorl may act separately, so that when put in motion they will
draw the gas through the carbonator.
The whorls of the screw, revolving half in the solution, they will always have a film
of liquor upon the half which is above the solution. The salt in the liquor is instantly
carbonated, being in a thin film on the whorls, and the gas being drawn into contact
with it by the motion. The number of discs in a carbonator will be regulated by the
quantity of gas between two discs, and the strength of the solution, so that the salt on
the whole of the discs above the solution at one time shall be sufficient to take up the
whole of the carbonic anhydride between two of the discs.
The tank in which the screw revolves should be sufficiently deep below the discs, so
that the liquor may flow back underneath, as it will have been drawn forward by the
motion of the screw.
The carbonator is connected at its inlet end, with the furnace, from which by
the revolution of the screw, the carbonic anhydride will be drawn in, and at its outlet
end, it is connected with a sulphuric acid chamber, for the exit of the hydrogen
sulphide, which is lighted to reproduce sulphuric acid.
In practice, it will be better to use two carbonators in series, the one last charged
always receiving the gas from the one in which the salt is partly carbonated. This
will save gas, because though the sulphide continually diminishes in the solution, the
gas does not diminish.
To this carbonator there must be added a gas washer, altogether similar to the
carbonator, but much smaller than the carbonator, and this gas washer may be charged
with chalk-water so that the sulphurus acid and other impurities from the furnace may
be washed out. The gas washer and carbonator being in the screw-form above
described will obviate the necessity for any exhaust or blowing apparatus being used.
The first reaction is represented by the following equation :
Na, SO + C + O₁ = Na, S + 400,
4
4
4
the carbon taking half its oxygen from the sulphate, and the other half in its passage
to the flue or outlet, and this carbonic anhydride should be used to carbonate preceding
charges of sulphide. The carbonic anhydride may be partly cooled before passing to
the washer, by being passed under a large tank or vat of carbonate solution, and it
will, at the same time, assist in evaporating the water.
The second reaction is represented by the following equation:
Na, SH, O + CO₂ = Na, CO, + H, S,

page_text: When the solution of sodium sulphide is so far carbonated that it begins to deposit
acid carbonate, commonly called bicarbonate, the operation may be stopped, and the
liquor drawn off and boiled until any sodium sulphide that it may still contain is
decomposed, and carbonated by a reaction with the acid carbonate, which has been
formed in it the whole being reduced to neutral carbonate, thus :
When the solution of sodium sulphide is so far carbonated that it begins to deposit
acid carbonate, commonly called bicarbonate, the operation may be stopped, and the
liquor drawn off and boiled until any sodium sulphide that it may still contain is
decomposed, and carbonated by a reaction with the acid carbonate, which has been
formed in it the whole being reduced to neutral carbonate, thus:
Na, S2 (HNa CO₂)
==
2 (Na, CO₂) + H, S,
When the solution ceases to colour acetate of lead paper, the boiling may be stopped
and the solution run off to stand to allow the fine particles of carbon to settle, which
have been liberated by the carbonating and boiling, a clear solution of soda carbonate
will thus be obtained.
It is evident from the above reaction that if one charge of solution be reduced to
acid carbonate and this be boiled with one charge of crude sulphide solution the two
will be reduced to neutral carbonate, and this can be done if required.
ERNEST DE PASS, Fel. Inst. P.A.,
68, Fleet Street, London,
Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Soda and in Apparatus for
the Purpose.
I, JACOB BAYNES THOMPSON, of 130 Queen's Road, Peckham, in the County of
Surrey, 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 (reference being had to the accompanying drawings
and to the letters and figures marked thereon) that is to say :-
My invention has for its object improvements in the mode or method of manufac-
turing soda by the sulphide process, and consists :
First in the reduction of sodium sulphate to sodium sulphide.
Secondly, in the mode, of converting the sodium sulphide into neutral sodium
carbonate, and
Thirdly, in the apparatus by means of which that reaction is effected.
It has been found that when sodium sulphate is deoxidised to sodium sulphide by
not more than double the theoretic quantity of carbon, if the heat of the furnace be
above bright red, the sulphide is decomposed by the silicic acid of the bricks
of the furnace, thus silicate of soda is formed at the expense of the furnace, or
if reduced in iron it attacks the iron, iron sulphide being formed, that is when the
carbon is not more than one third by weight of the sodium sulphate.
Now, I have found that when the carbon is equal in weight to one half of the
sulphate the resulting sulphide is masked by the excess of carbon and is not then in
a fluid state, and does not then attack fire bricks. I therefore add to the sodium
sulphate one half its weight of powdered coal, or other form of carbon, the two being
intimately mixed.
This mixture is put into a species of reverberatory furnace which has been previously
heated to 1000° Centigrade (or bright red) and allowed to remain quietly at about
800° Centigrade, or full red, until carbonic oxide ceases to burn on its surface. When
the tongues of flame cease to appear the sulphate is deoxidised and the sulphide may
be removed from the furnace and allowed to cool, but it should be protected from
the air.
The reverberatory furnace mentioned above should be one that does not admit more
air than is necessary for the thorough oxidation of the fuel in the combustion chamber,
and the carbonic oxide in the reverberator, otherwise the free oxygen will act on the
mixture in the reverberator which is to be avoided, but if too much free oxygen-
should pass in, then that may be corrected by throwing a little powdered coal over the
top of the mixture.
The sodium sulphide when cold is dissolved out in a suitable tank, and the excess of
carbon allowed to settle, or is otherwise separated. The clear liquor is then run into
an apparatus which I will call the " Carbonator," and which is described herein-
after. The excess of carbon which has been separated may be used again for
reducing more sulphate.
Now, in order to be enabled to explain the action of the carbonic acid on the
sulphide in the solution, it will be necessary to describe generally the carbonator,
referred to above, in conjunction with the process effected by it.

page_text: This carbonator is in the form of a long tank, with a semi-circular air-tight cover,
in which revolves a series of discs on a spindle. Each disc is cut down on one side
to near its centre and is then twisted into the form of one whorl of a screw, so that
when the whorls are fixed on the spindle, or shaft, they form a continuous screw,
the whorls being fixed to follow each other in that form. Or they may be fixed dis-
continuously that each whorl may act separately, so that when put in motion they will
draw the gas through the carbonator.
The whorls of the screw revolving half in the solution they will always have a film
of liquor upon the half which is above the solution. The salt in the liquor is instantly
carbonated, being in a thin film on the whorls, and the gas being drawn into contact..
with it by the motion. The number of discs in a carbonator will be regulated by the
quantity of gas between two discs, and the strength of the solution, so that the salt on
the whole of the discs above the solution at one time shall at least be sufficient to take
up the whole of the carbonic anhydride between two of the discs.
The tank in which the screw revolves should be sufficiently deep below the discs so
that the liquor may flow back underneath, as it will have been drawn forward by the
motion of the screw.
The carbonator is connected at its inlet end with the furnace from which, by the
revolution of the screw, the carbonic anhydride will be drawn in, and at its outlet for
the hydrogen sulphide it is connected with a sulphuric acid chamber, or other recipient,
for the hydrogen sulphide such as a kiln for the recovery of the sulphur, or a
gas holder to store it for use in either way.
In my Provisional Specification I mentioned the use of two carbonators, but I have
since discovered that it will be more advantageous to use three carbonators, I therefore
now use three in series; the one last charged always receiving the gas from the other
two in which the salt is partly carbonated. This will save gas, because although the
sulphide continuously diminishes in the solution, the gas does not diminish.
To this carbonator, there must be added a gas washer, altogether similar to the
carbonator, and this gas washer may be charged with chalk-water so that the
sulphurus acid, and other impurities from the furnace, may be washed out. The
gas washer and carbonator being in the screw form above described will obviate
the necessity for any exhaust or blowing apparatus being used.
L
canted l the followin

page_text: It is evident from the above reaction that if one charge of solution be reduced to
acid carbonate and this be boiled with one chargo of crude sulphide solution the two
will be reduced to neutral carbonate, and this can be done if required.
In the accompanying drawings, Fig. 1 shews a longitudinal section of a series of
three carbonators, and a gas washer.
Fig. 2 is a perspective view in elevation of the same.
Figs. 3 and 4 are respectively a face view and an edge view of one of the
whorls.
A is the gas washer, and B1, B2, B3, the carbonators.
a,
is the screw-b, the inlet exit and connecting gas pipes-c, the screw shaft-
d, the driving pulley mounted thereon-e, the connecting solution pipes and cocks-
f, the solution exit cocks-g, gauge glass to shew when bi-carbonate is formed-h, small
taps to shew when tanks are full-n, is the feed pipe for the chalk water, and o the
feed pipe for the soda solution.
The following is the mode of working a 20% solution.
When the solution in the first carbonator begins to deposit bicarbonate it is run
out, but the motion of the screw is not stopped. While it has been carbonating, the
hydrogen sulphide (H, S) has passed into the carbonator B' and has been absorbed,
but the nitrogen (N) which accompanied the carbonic anhydride (CO2) will pass on
and out of B at 6. The solution in carbonator B2 has now become hydrogen and
sodium sulphide (2HNa S). When the liquor is being run out of carbonator B', the
cock i is closed, and the cock k is open, and carbonic anhydride (CO) begins to pass
into carbonator B2, then hydrogen sulphide (H, S) passes out through the cock k, and
the tap m may be opened, and the hydrogen sulphide issuing therefrom is ignited.
As long as the hydrogen sulphide burns, the cock k is left open, and the cock i closed;
when it ceases to burn the cock i is opened and the cock k closed. When bi-carbonate
falls into the carbonator B' motion is stopped and the solution is run out and boiled.
Then the solution from carbonator B is run into carbonators B2 and B', and a fresh
solution is run in at feed pipe o, till they are all full, and fresh chalk-water is run into
the washer and the operation is recommenced.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
.
1. The herein described mode of reducing the whole of the sulphide solution to
neutral carbonate, that is by heating the solution as soon as bicarbonate has been
deposited, which decomposes the bicarbonate into neutral carbonate and carbonic
acid, and this acid reacts upon the residual sulphide, producing neutral carbonate
and hydrogen sulphide which passes off and leaves in solution neutral carbonate
only.
2. The form and construction of the carbonator, the same consisting essentially of a
series of discs mounted on a spindle, said discs having been cut down and twisted into
the whorls of a continuous screw, together with the arrangement of the pipes and
cocks for the gas and solution as described and shewn.
3. The mode of working the carbonator, that is by revolving the screw so that its
discs continually renew the film of solution upon them, and at the same time draw the
gas into contact with the solution so that it instantly carbonated; also the mode of
getting rid of part of the nitrogen which is mixed with the carbonic anhydride, and
the mode of taking off the strong hydrogen sulphide, as described.