IMPROVEMENTS IN THE MEANS OF AND' APPARATUS FOR THE MANUFACTURE OF SULPHIDE OF SODIUM AND SULPHIDE OF POTASSIUM, WHICH APPARATUS CAN BE APPLIED TO THE MANUFACTURE OF 'BLACK ASH
Year: 1876

page_text: LETTERS PATENT to Walter Weldon, of Abbey Lodge, Merton, in the County
of Surrey, for the Invention of "IMPROVEMENTS IN THE MEANS OF AND'
APPARATUS FOR THE MANUFACTURE OF SULPHIDE OF SODIUM AND SULPHIDE
OF POTASSIUM, WHICH APPARATUS CAN BE APPLIED TO THE MANUFACTURE OF
'BLACK ASH'."
Sealed the 24th November 1876, and dated the 28th August 1876.
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the Office.
of the Commissioners of Patents on the 28th August 1876.
•
"
WALTER WELDON, of Abbey Lodge, Merton, in the County of Surrey IM-
PROVEMENTS IN THE MEANS OF AND APPARATUS FOR THE MANUFACTURE OF
SULPHIDE OF SODIUM AND SULPHIDE OF POTASSIUM, WHICH APPARATUS CAN BE
APPLIED TO THE MANUFACTURE OF BLACK ASHI'."
'
It has been many times proposed, and, although less frequently, it has been many
times attempted, to manufacture soda by converting sulphate of soda into sulphide
of sodium, and then decomposing such sulphide of sodium by one or other of several.
known means. This method of manufacturing soda would permit the recovery and
reutilization of the whole of the sulphur contained in the sulphate of soda
employed, and would avoid the production of the offensive residue known as
"alkali waste," but all attempts to practically apply this method have hitherto
failed.
A principal cause of this failure has been the very powerfully corrosive action of
sulphide of sodium upon the materials of which all furnaces or other apparatus for
the manufacture of that body have hitherto been constructed. The manufacture of
sulphide of sodium has usually been attempted by heating to a suitable temperature'
a mixture of sulphate of soda with coal, coke, or other form of carbonaceous matter, '
and the furnaces or other apparatus employed have usually been constructed either
of brick or of cast iron. Sulphide of sodium however at a high temperature attacks
both these materials with extreme energy. Hence when only enough carbonaceous
matter to decompose the sulphate of soda has been used, the furnaces employed '
have become useless after a very few operations, and the product obtained has
been largely contaminated by compounds resulting from the reaction of sulphide of '
sodium upon the materials of which the furnaces have been formed. When an
.

page_text: excess of carbonaceous matter has been employed the contact of the resulting
sulphide of sodium with the material of the furnaces has been less intimate, and the
wear of the furnaces has consequently been less than in the other case; but the
wear of the furnaces has still been excessive, and although the product has con-
tained a smaller proportion of impurities due to corrosion of the furnaces or other
apparatus, it has contained in addition a more or less considerable residue of car-
bonaceous matter.
The furnaces or other apparatus in which it has hitherto been attempted to
manufacture sulphide of sodium have thus worn out too rapidly to permit of the
manufacture being continued, and the product obtained in such furnaces or other
apparatus has always been extremely impure.
The object of the present Invention is to provide apparatus for the manufacture
of sulphide of sodium, which shall not be liable to corrosion thereby, and which,
while thus avoiding what has hither to rendered the first step in the process referred
to in the first paragraph of this Specification impracticably costly, shall at the same
time render possible and easy the production of a very much purer sulphide of
sodium than has ever hitherto been obtained.
I accomplish this object by lining with blocks of carbon the furnaces or other
apparatus in which the sulphide of sodium is to be manufactured This carbon
lining may be inade of the compact graphite which is formed in gas retorts, or of
certain kinds of native graphite, but it will generally be cheaper and more con-
venient to employ artificial blocks or bricks obtained by mixing powdered coke with
gas tar, submitting the mixture to powerful pressure in suitable moulds, and then
heating the blocks or bricks so obtained in such manner and under such conditions
that the tar in them shall undergo desti uctive distillation, without the blocks or bricks
themselves losing their shape during the operation. Other kinds of charcoal may
of course be used instead of coke, and such other agglutinating bodies as leave a
residue of carbon when subjected to destructive distillation may be used instead of
tar, but coke and tar will usually be most convenient. The blocks or bricks may
be of any suitable size or shape, but I prefer that they should be so shapen as to be
capable of fitting into one another. And in fitting them together in the furnaces or
other apparatus to be lined with them I prefer to smear those surfaces of them
which are to come into mutual contact either with tar or with a mixture of tar and
powdered coke.
The kind of apparatus in which, when lined with carbon blocks as above set
forth, sulphide of sodium can be manufactured most advantageously is the sort of
furnace which is known to alkali manufacturers as the "revolving furnace." In
almost any other kind of furnace the charge operated upon would have to be
stirred from time to time with iron tools, which tools would be rapidly eaten away
by sulphide of sodium, much of the said sulphide becoming thereby converted into
double sulphide of sodium and iron. The sulphide of sodium in such double
sulphide could not be converted into soda by any practicable means, and the
presence of such double sulphide with the remainder of the sulphide of sodium
would greatly increase the cost of the conversion of the latter into merchantable
soda. While therefore I do not confine myself to this form of apparatus I regard &
carbon lined revolving furnace, in which to effect the reaction upon sulphate of
soda of either solid carbonaceous matter or deoxidizing gases, in order to the pro-
duction of sulphide of sodium, as being the especial feature of thus Invention. Such
a furnace will render the manufacture of sulphide of sodium industrially practicable
for the first time, and will yield sulphide of sodium of such quality as to be in effect
a new product.
What has hitherto been obtained as sulphide of sodium has really been a mixture
of many bodies, requiring complicated treatment for its conversion into iner-
chantable soda, and indeed usually containing compounds not capable of being
converted thereinto, but by means of a carbon lined revolving furnace it will be
easy to produce almost chemically puie sulphide of sodium capable of conversion
into merchantable soda by much simpler means than any hitherto proposed.

page_text: Such carbon lined furnace or furnaces are equally applicable to the manufacture
of sulphide of potassium, and may also in some cases be applied with advantage to
the manufacture of what is known as "black ash”
When a revolving furnace lined with carbon blocks is used for the manufacture
of sulphide of sodium, either by treating sulphate of soda with deoxidizing gases or
by heating by direct contact with products of combustion a mixture of sulphate of
soda and solid carbonaceous matter, the furnace so employed must be open at both
ends in the same manner as the revolving furnaces at present in use among manu-
facturers of alkali; but for the manufacture of sulphide of sodium by the new
method of causing sulphate of soda and carbonaceous matter to react upon each
other, which I have described in another Specification, which will be deposited at
the Patent Office on the same day as this, the revolving furnace employed must
not only be lined with carbon blocks, but must also be provided with appliances
for cutting off at will the entry into it of products of combustion, and also with
appliances for completely closing the opening at one of its ends, so that the furnace
shall be capable of being converted at will into a vessel having only one open aperture.
These appliances will be more particularly described in my final Specification.
When the sulphide of sodium is treated for its conversion into soda or otherwise
in apparatus other than the furnace in which it was formed, and thus has to he
transferred from that furnace in the state of sulphide of sodium, the intermediate
vessels employed to receive it must also be lined with carbon blocks.
'
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Walter Weldon in the Great Seal Patent Office on the 26th February
1877.
WALTER WELDON, of, Abbey Lodge, Merton, in the County of Surrey "TM-
PROVEMENTS IN THE MEANS OF AND APPARATUS FOR THE MANUFACTURE OF SULPHIDE
OF SODIUM AND SULPHIDE OF POTASSIUM, WHICH APPARATUS CAN BE APPLIED TO
THE MANUFACTURE OF BLACK ASIL."
It has been many times proposed, and, although less frequently, it has been many
times attempted to manufacture soda by converting sulphate of soda into sulphide
of sodium, and then decomposing such sulphide of sodium by carbonic acid or other
suitable agent. This method of manufacturing soda would permit the recovery
and reutilization of the whole of the sulphur contained in the sulphate of soda
employed, and would avoid the production of the offensive residue known as
"alkali waste;" but all attempts to practically apply this method have hitherto
failed.
A principal cause of this failure has been the very powerfully corrosive action of
sulphide of sodium upon the materials of which all furnaces or other apparatus for
the manufacture of that body have hitherto been constructed. The manufacture
of sulphide of sodium has usually been attempted by heating a mixture of sulphate
of soda with coal, coke, or other form of carbonaceous matter in furnaces or other
apparatus constructed either of brick or of cast iron. Sulphide of sodium, however,
attacks both these materials with such energy that the furnaces or other apparatus
employed have been rendered useless after a very few operations, while the product
obtained instead of being pure sulphide of sodium has consisted in very large part
of the bodies which are formed by the reaction of sulphide of sodium upon brick
or iron as the case might be.
The principal object of my present Invention is to provide apparatus for the
manufacture of sulphide of sodium which shall not be liable to corrosion thereby,
and which shall thus permit the production of sulphide of sodium much more
economically than it has ever been produced hitherto, and at the same time of such
purity as to be practically a new product.

page_text: I accomplish this object by lining the furnaces or other apparatus in which sul-
phide of sodium is to be manufactured either with blocks of gas retort carbon, or,
as will usually be cheaper and more convenient, with blocks or bricks of artificially
agglomerated and hardly compressed coke, obtained in accordance with an Invention
for which I have received Letters Patent, numbered 3382, of the year 1876, by
intimately mixing powdered coke with a small quantity of gas tar, subjecting the
mixture to powerful pressure in suitable moulds, and then heating the blocks or
bricks so obtained until the tar in them shall have completely undergone destructive
distillation, the blocks or bricks being prevented from losing their shape or mate-
rially altering their dimensions during such heating by being encased or enclosed on
all sides by suitably fitting iron plates or other equivalent appliances firmly clamped
or bolted together. I prefer that such blocks or bricks should be so shapen as to be
capable of fitting into one another, and in fitting them together in the furnaces
or other apparatus to be lined with thein I prefer to smear those surfaces of them
which are to come into mutual contact either with tar or with a mixture of tar and
powdered coke.
While the application of that part of my present Invention which consists in
lining either with gas retort graphite or with artificially agglomerated and com-
pressed coke or other form of carbon the furnaces or other apparatus to be used for
the manufacture of sulphide of sodium is not confined to any particular kind of
furnace or other apparatus to be used as aforesaid, my present Invention further
relates to the employment for the manufacturo of sulphide of sodium, and to the
necessary adaptation to that end of what is known as the "revolving furnace."
The revolving furnace as at present in nearly general use nunong manufacturers of
soda is an iron cylinder lined with fire-brick; it is placed horizontally, and is so
disposed that it can be made at will to revolve on its longer axis. It is partially
closed at each end, but in one of its ends is an aperture for the entrance into it of
products of combustion supplied to it from another furnace or combustion chamber,
and in its other end is a corresponding aperture by which the said products.of
combustion pass off after having communicated more or less of their heat to the
contents of the cylinder. While products of combustion are thus passing into and
through it the cylinder or "revolving furnace" is kept in revolution. Between it
and the furnace or combustion chamber, which supplies it with hot products of
_ combustion, there is suspended an annular disc of fire-clay, bound round by a stout
iron hoop, and so disposed as not quite to touch either the revolving furnace on the
one hand, or the furnace for supplying products of combustion on the other. To
enter the revolving furnace the products of combustion pass through the aperture
in the centre of this disc.
When it is desired to employ such a furnace for the manufacture of sulphide of
sodium, if the method by which the sulphide is to be manufactured is either that of
treating -sulphate of soda by a hot deoxidizing gas, or that of heating by direct
contact with products of combustion a mixture of sulphate of soda and solid
carbonaceous matter, the revolving furnace to be so employed need differ from the
revolving furnaces at present in use only in being lined internally with blocks of
carbon instead of with blocks of fire-clay, and in having a rim or flange of carbon
round the man hole, by which it is charged and discharged, in order to permit of
fused sulphide of sodium being discharged therefrom without coming into contact
with the iron envelope of the furnace. When however sulphide of sodium is to be
manufactured in a revolving furnace in accordance with the new method of applying
the heat necessary to enable carbonaceous matter to react on sulphate of soda, for
which I have received Letters Patent, numbered 3381, of the year 1876, the said
furnace must not only be lined and otherwise protected by blocks of carbon as
aforesaid, but it must also be capable of being converted at will into a vessel
completely closed at one end, by substituting for the suspended annular disc of fire-
clay through the aperture in the centre of which products of combustion at other
times pass into it a disc of carbon having no aperture, and instead of suspending
this disc between the revolving furnace, and the furnace for supplying products of

page_text: combustion, attaching it to the end of this revolving furnace in such wise that it
shall completely close the aperture therein, and that while thus closing that aperture
it shall revolve with the furnace If the annular disc be suspended by a rod or
chain in such wise that it can move in the same manner as a pendulum, and so
be readily drawn aside by means of another rod or chain, and if the carbon disc
supported on edge on a suitable carriage be held ready to be pushed forward so as
to take the place of the annular disc the moment the latter has been drawn aside,
and if means of rapidly affixing the carbon disc to the end of the furnace have
been provided, the conversion of the revolving furnace from a vessel into which
products of combustion were entering at one end, and from which they were
passing out at the other end into a vessel perfectly closed at that end by which the
products of combustion were previously entering, may be effected in an extremely
brief space of time The means of attaching the carbon disc to the end of the
revolving furnace may be varied in many ways, but a simple means consists in
having a flange to the iron hoop enclosing the carbon disc, and having three or
more holes in this flange corresponding to bolts projecting from the end of the
furnace.
•
When sulphide of sodium is to be treated for its conversion into soda or other-
wise, in apparatus other than the furnace in which it was formed, and thus has to
be transferied in the state of fusion, the intermediate vessels employed to receive
it should also be lined with carbon blocks.
This Invention is eqally applicable to the manufacture of sulphide of potassium.
Having now described and ascertained the nature of my said Invention, and in
what manner the same is to be performed, I claim as the Invention to be secured to
me by the heiein-before in part recited Letters Patent.
Firstly. Lining with gas retort graphite or with artificially agglomerated and
compressed coke or other form of carbon the furnaces or other apparatus to be used
for the manufacture of sulphide of sodium or of sulphide of potassium, and also
the vessels into which sulphide of sodium or sulphide of potassium is discharged
therefrom in the fused state.
And, Secondly. The use for the manufacture of sulphide of sodium and of
sulphide of potassium of a revolving furnace lined with carbon as aforesaid, and
also of a revolving furnace disposed so as to be capable of being converted at will
into a vessel closed at one end, substantially as is above described.
In witness whereof, I, the said Walter Weldon, have hereunto set my hand and
seal this Second day of February, in the year of our Lord One thousand
eight hundred and seventy-seven.
(L.S.)
WALTER WELDON.