IMPROVEMENTS IN THE MANUFACTURE OF SULPHIDE OF SODIUM AND ALSO OF SULPHIDE OF POTASSIUM
Year: 1877

page_text: LETTERS PATENT to Walter Weldon, of Abbey Lodge, Merton, in the County
of Surrey, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
SULPHIDE OF SODIUM AND ALSO OF SULPHIDE OF POTASSIUM"
Sealed the 17th April 1877, and dated the 2nd February 1877,
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the Office
of the Commissioners of Patents on the 2nd February 1877
WALTER WELDON, of Abbey Lodge, Merton, in the County of Surrey
"IM-
PROVEMENTS IN THE MANUFACTURE OF SULPHIDE OF SODIUM AND OF SULPHIDE
OF POTASSIUM"
This Invention relates to the manufacture of sulphide of sodium and sulphide of
potassium by heating sulphate of soda or sulphate of potash in admixture with solid
carbonaceous matter
The said Invention consists, firstly, in heating sulphate of soda or sulphate of
potash with a proportion of coke or charcoal not greater, or only very barely greater,
than the quantity necessary to form carbonic anhydride, or CO, with the oxygen
contained in the said sulphates This proportion in the case of sulphate of soda is
about seventeen per cent of the weight of the sulphate, and in the case of sulphate
of potash is about fifteen per cent of the weight thereof. These are the proportions
supposing the coke or charcoal to consist entirely of pure carbon. When it does not
consist entirely of pure carbon, as it usually will not, allowance must be made for
the foreign bodies contained in it in such wise that the proportions of real carbon
employed may be substantially as aforesaid The object of using these special pro-
portions is to avoid the production of carbonic oxide, and thus to secure that by the
operation yielding the sulphide itself, there shall at the same time be produced
carbonic anhydride in sufficient quantity and sufficiently pure to permit of the sul-
phide being afterwards converted into carbonate by means of it
The said Invention consists, secondly, in heating sulphate of soda or sulphate of
potash mixed with coke or charcoal in the proportions aforesaid, when the sulphide
to be obtained is afterwards to be converted into carbonate, and it is therefore
desired to produce at the same time as the sulphide pure carbonic anhydride, or

page_text: when the sulphide is not afterwards to be converted into carbonate and the pro-
duction of cai bonic anhydride, therefore need not be provided for, mixed with such
other proportion of coke, charcoal, coal, or other carbonaceous matter as may be
preferred, in apparatus lined with blocks on bricks of carbon, such blocks or bricks
being preferably though not necessarily such as may be obtained by mixing pow-
dered coke with gas tar, filling the mixture into suitable moulds, and then heating
the blocks or bricks so formed until the tai in then has completely undergone
destructive distillation The carbon lined apparatus to be employed for this purpose
must be either a muffle furnace on a retort heated externally when it is desired to
obtain carbonic anhydride as well as sulphide of sodium or of potash, but in other
cases it may be either a reverberatory or a revolving furnace, as may be preferred.
The said Invention consists, thundly, in conducting the manufacture of sulphide of
sodium or sulphide of potassium by first heating sulphate of soda or sulphate of
potash to fusion in any suitable furnace, which may preferably be a Siemens's rege-
nerative furnace, and then running the fused sulphate on to powdered coke or
charcoal contained in a inuffle furnace, retort, or other vessel to which heat is
applied externally, and which furnace, retort, or other vessel can and shall be com-
pletely closed after the fused sulphate has been admitted thereinto, except as regards
a conduit for conveying away the resulting carbonic anhydride I prefer that
before the fused sulphate is admitted into the said muffle furnace, retoit, or other
apparatus as aforesaid that the coke or charcoal which has fist been charged
thereinto should have remained therein sufficiently long to have become heated to
redness
This Invention consists, lastly, in facilitating the reaction of carbonaceous matter
upon sulphate of soda or sulphate of potash when that reaction is performed in a
muffle furnace, retort, or other vessel, closed while the reaction is going on except
as regards its communication with the conduit for carbonic anhydride aforesaid, by
diawing off the carbonic anhydride by means of a fan, au pump, or other exhausting
apparatus connected with that conduit in such wise as to diminish the pressure of
the atmosphere of carbonic anhydride contained in the furnace or vessel in which
the reaction of the carbonaceous matter upon the sulphate is going on
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Walter Weldon in the Great Seal Patent Office on the 2nd August
1877.
" IM-
WALTER WELDON, of Abbey Lodge, Merton, in the County of Surrey
PROVEMENTS IN THE MANUFACTURE OF SULPHIDE OF SODIUM AND OF SULPHIDE
OF POTASSIUM”
This Invention relates to the manufacture of sulphide of sodium and of sulphido
of potassium by the reaction at a suitable temperature of solid carbonaceous matter
upon sulphate of soda or sulphate of potash, as the case may be
It consists, firstly, in employing for the reduction of the said sulphates to the
state of sulphides proportions of coke or charcoal not greater, or only baiely greater,
than the quantities necessary to form carbonic anhydride, or CO, with the oxygen
of the said sulphates in accordance with the equations
Na. SO.+2C = Na₂ S + 2 CO,
and
K, SO, 2C K₂S + 2 CO₂
carbon required
Supposing the sulphates to be perfectly puie, the quantities of pure
by these equations aio, in the case of sulphate of soda 169 per cent of the weight
of the sulphate, and in the case of sulphate of potash 136 per cent of its
weight. I use slightly, but only slightly, inore than these proportions of carbon,
making allowance of course, as will be well understood, for any impurities con-

page_text: tained either in the sulphates or in the coke or charcoal employed I thus use not
inore than half the smallest proportion of carbonaceous matter prescribed by any
others before me The smallest proportion of carbonaceous matter which I have
found mentioned in the Specification of any previous Patent for the manufacture of
alkaline sulphides is that given in the Specification of the Patent Numbered 2612
of the year 1859, in which "a mixture of sulphate of soda in powder with about
half its weight of small coal or one-thud of its weight of coke" is advised. When
such a mixture is heated, however, to the temperature at which the sulphate in it
becomes reduced to sulphide, the gaseous product obtained is carbonic oxide, or CO,
and not carbonic anhydride, or CO,, whereas to the realization of that which it is
the primary object of this Invention to render practicable, namely, the manufacture
of carbonates of soda and potash by way of the intermediate production of the sul-
phides of sodium and potassium, it is absolutely essential that the secondary product
of the caction by which the said sulphides are obtained should be carbonic anhy-
dude, or CO₂
The present Invention consists, secondly, in conducting the manufacture of sul-
phide of sodium or sulphide of potassium, whatever proportions of coke or charcoal
inay be employed, by first heating sulphate of soda or sulphate of potash to fusion
in one furnace, and then running the fused sulphate on to powdered coke or char-
coal contained in a second furnace, such second furnace being a muffle furnace,
retoit, or other vessel to which heat is applied externally, and which can and shall be
completely closed after the fused sulphate has been admitted thereinto, except that
it shall communicate with a conduit for conveying away the gaseous product of the
decomposition of the sulphate I prefer that, before the fused sulphate is admitted into
the said second furnace, the coke or charcoal previously charged into that furnace
should have remained therein sufficiently long to have become heated to redness
For the fusion of the sulphate I do not clum or confine myself to any particular
kind of furnace, but what is known as a Siemens's furnace may conveniently be
used, the sulphate being heated therein by duect contact with a gas flame, but care
being taken that this flame while in contact with the sulphate shall never become
reducing The second furnace may be any kind of muffle or "close" furnace, but
although this forms no part of tho present Invention, it should be lined with some
material which is not attacked by a fused alkaline sulphide It may conveniently
be lined with blocks of carbon, obtained either as described in the Specification of
my Patent Numbered 3382 of the year 1876, or in any other convenient way. It
must be so placed in reference to the furnace devoted to the fusion of the sulphate
that fused sulphate from the latter fui nace can be readily run into it through an
aperture, which can then be closed by a plug or damper, preferably of carbon, this
aperture should either be in the 100f of the furnace or otherwise in the upper part
of it The coke or charcoal may be charged by the same aperture. Near the
bottom of the furnace must be another aperture, by which fused sulphide may be
run out from time to time, this aperture or discharging hole must be closed when
not in use by a carbon plug or otlici convenient appliance The upper part of the
furnace must communicate with a conduit for conveying away the carbonic anhy-
dude or other gaseous product of the reaction performed in it
The present Invention consists, thudly, in facilitating the production of puie
sulphide of sodium or of potassium, and at the same time of pure carbonic anhy-
dide, when the said sulphides are manufactured by the reaction of solid carbonaceous
matter upon sulphate of soda or sulphate of potash, and that reaction is performed
in a muffle furnace, ietoit, or other vessel, closed whilst the reaction is going on
except as regards its communication with the conduit for the gaseous product of the
reaction as aforesaid, by drawing off the said gaseous product by means of a fan, air
pump, or other exhausting apparatus, placed in or other wise suitably connected with
that conduit in such wise as to diminish the pressure of the atmosphere of carbonic
anhydride or other gaseous product contained in the furnace or vessel in which the
reaction of the carbonaceous matter upon the sulphate is going on I find that
sulphide of sodium and sulphide of potassium at a high temperature deoxidize car

page_text: bonic anhydride, and that the more rapidly the carbonic anhydride resulting from
the reaction of solid carbonaceous matter upon sulphate of soda or sulphate of potash
18 withdrawn from the vessels in which that reaction is being performed, the smaller
the extent to which this prejudicial reverse action takes place
Having now particularly described and ascertained the nature of my said Inven-
tion, and in what manner the same is to be performed, I claim as the Invention to
be secured to me by the herein-before in part recited Letters Patent,-
Firstly Employing for the reduction of sulphate of soda to the state of sulphide
of sodium, and of sulphate of potash to the state of sulphide of potassium, proportions
of coke or charcoal substantially such as are set forth above.
Secondly Conducting the manufacture of sulphide of sodium and of sulphide of
potassium by beating sulphate of soda oi sulphate of potash to fusion in one furnace,
reverberatory or other, and then causing the fused sulphate to react upon powdered
coke or charcoal in a second furnace, such second furnace being heated externally
and having all its apertures closed while the reaction is going on within it except
one communicating with a conduit for conveying away the gaseous product of the
reaction, substantially as is above described
And, Thudly. Withdrawing by mechanical means from the furnaces or other
vessels in which solid carbonaceous matter is 1eacting on sulphate of soda or sulphate
of potash the carbonic anhydride or other gaseous product of that reaction, substan-
tually as and for the purpose above set forth.
In witness whereof, I, the said Walter Weldon, have hereunto set my hand
and seal, this Twenty-sixth day of July, in the year of our Loid One
thousand eight hundred and seventy-seven