A NEW METHOD OR PROCESS AND A NEW COMBINATION OF PROCESSES AND APPLIANCES FOR OBTAINING FROM SULPHIDE OF SODIUM AND SULPHIDE OF POTASSIUM ALUMINATE AND PHOSPHATE OF Soda OR POTASIL AND EITHER FREE SULPHUR OR SULPHUROUS ACID."
Year: 1876

page_text: LETTERS PATENT to Walter Weldon, of Abbey Lodge, Merton, in the County of
Surrey, for the Invention of "A NEW METHOD OR PROCESS AND A NEW
COMBINATION OF PROCESSES AND APPLIANCES FOR OBTAINING FROM SULPHIDE
OF SODIUM AND SULPHIDE OF POTASSIUM ALUMINATE AND PHOSPHATE OF Soda
OR POTASIL AND EITHER FREE SULPHUR OR SULPHUROUS ACID."
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. "A. NEW
METHOD OR PROCESS AND A NEW COMBINATION OF PROCESSES AND APPLIANCES FOR
OBTAINING FROM SULPHIDE OF SODIUM AND SULPHIDE OF POTASSIUM ALUMINATE
AND PHOSPHate of Soda OR POTASH AND EITHER FREE SULPHUR OR SULPHUROUS
ACID."
In certain other Specifications, which will be deposited at the Patent Office on
the same day as this, I have described certain Inventions relating to the manu-
facture of sulphide of sodium and sulphide of potassium, whereby I believe that
these bodies can henceforth be produced so economically as to permit of their being
applied to a number of new and very important purposes My present Invention
consists in transforming them into phosphate and aluminate of soda or potash, and
in at the same time obtaining their sulphur either as free sulphur or as sulphurous
acid by a process by which I also turn to important account those hitherto un-
utilized substances, the native phosphates of alumina.
It will be convenient to speak below only of sulphide of sodium and of phos-
phate and aluminate of soda, but whatever is said of these compounds will be
equally applicable also to the corresponding compounds of potassium.
Sulphide of sodium manufactured in accordance with my other Inventions aforesaid
will be produced in a cylindrical furnace placed horizontally, arranged so as to be
capable of revolving on its longer axis, and having an opening at each end to
permit of the entry into it and of the passage through it of products of combustion,
or other gases or vapours.
For the purpose of my present Invention such cylindrical or "revolving
furnace must have connected with it at one end an apparatus for producing highly
--

page_text: .superheated steam, and at the other end an apparatus for treating sulphuretted
hydrogen.
The application of my present Invention begins when the said revolving furnace
contains a charge of sulphide of sodium, which has either been produced therein
or has been otherwise produced, and afterwards charged thereinto. I now add to
the said sulphide of sodium so contained in the revolving furnace finely powdered
phosphate of alumina, and I then send into the furnace super heated stoam. While
superheated steam is thus passing into the furnace I keep the furnace in revo-
lution, so that the steam shall come into contact with all parts of its contents.
Under these conditions the steam reacts on the sulphide of sodium, forming on
the one hand sulphuretted hydrogen, which passes off as gas, and on the other
hand caustic soda, which at the moment of its formation reacts on the phosphate
of alumina, producing first phosphate and afterwards aluminate of soda, or to some
extent the two simultaneously. What remains in the furnace when the reactions
aforesaid have taken place completely, which may be known by sulphuretted
hydrogen ceasing to be evolved, is a mixture of phosphate of soda and aluminate
of soda, which is then withdrawn from the furnace, and treated for the separation
and utilization of its constituents.
The sulphuretted hydrogen produced in the operation just described can be
treated in either of two ways. It will pass off mixed with steam, and the mixture
should preferably be cooled, so as to condense the steam out of it, leaving the
sulphuretted hydrogen nearly or quite pure. The sulpheretted bydrogen can then
be either simply burnt into sulphurous acid or treated for the obtainment of its
sulphur in the free state by the Invention for which Her Majesty's Letters Patent,
numbered 2008, and bearing date the 31st July 1871, have been granted to ine
But in applying that method of obtaining sulphur from sulphuretted hydrogen to
the sulphuretted hydrogen produced in treating sulphide of sodium by phosphate
of alumina and steam, as above described, I prefer to employ for the absorption of
the sulphuretted hydrogen either such apparatus as that which is described, and of
which Diawings are given in the Specification filed in pursuance of the condition
of Letters Patent, dated the 16th July 1873, and numbered 2449, or such new
apparatus as will be described in another Specification, which will be filed at the
Patent Office on the same day as this
The above described method of manufacturing phosphate and aluminate of soda
may be modified by using a blast of hot air instead of superheated steam. This
modification of the said method yields the sulphur of the sulphide of sodium directly
as sulphurous acid, but the sulphurous acid so yielded is less pure and more diluto
than that obtained by burning sulphuretted hydrogen produced by that form of the
said method which was first described.
Lastly, the manner of carrying the said method into effect may be modified by
using for the treatment of the mixture of sulphide of sodium and phosphate of
alumina by superheated steam or by hot air an apparatus other than the revolving
furnace. In such case the sulphide of sodium and the powdered phosphate of
alumina should be mixed together in the revolving furnace, and the mixture then
withdrawn therefrom and cooled. It should then be broken into small lumps, and
these lumps changed into vertical cylinders, and therein treated by the superheated
steam or hot air.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Walter Weldon in the Great Seal Patent Office on the 7th February
1877.
•
WALTER WELDON, of Abbey Lodge, Merton, in the County of Surrey. " A. NEW
METHOD OR PROCESS AND A NEW COMBINATION OF PROCESSES OR APPLIANCES FOR
OBTAINING FROM SULPHIDE OF SODIUM AND SULPHIDE OF POTASSIUM ALUMINATE
50

page_text: AND PHOSPHATE OF SODA OR POTASH AND EITHER FREE SULPHUR OR SULPHUROUS,
ACID."
This Invention consists in a new method or process, a combination of this
method or process with certain other methods or processes and a combination of
appliances, whereby I transform sulphide of sodium into phosphate and aluminate
of soda and sulphide of potassium into phosphate and aluminate of potash, and at
the same time obtain the sulphur of the said sulphides either as free sulphur or as
sulphurous acid.
In describing my said Invention it will be convenient to speak only of sulphide
of sodium and of phosphate and aluminate of soda; but all that is said of these will
be equally applicable to the corresponding compounds of potassium.
The said new method or process consists in inixing sulphide of sodium, preferably
in the state of fusion, with phosphate of alumina, native or other, preferably in fine
powder, and then treating the mixture by superheated steam. The steam reacts-
on the sulphide of sodium liberating its sulphur as sulphuretted hydrogen which
passes off as gas, and forming caustic soda, which caustic soda then reacts upon the
phosphate of alumina, combining with both the acid and the base of that compound,
forming phosphate of soda and aluminate of soda which are thus obtained in
admixture one with the other.
I combine this method of obtaining phosphate and aluminate of soda with one
or other of two methods of utilizing the sulphuretted hydrogen which is produced
at the same time. The said sulphuretted hydrogen passes off mixed with steam.
By one method of utilizing it I simply pass the mixture of sulphuretted hydrogen
and steam through cooling pipes or other convenient apparatus, whereby I separate
the steam by condensation and then burn the sulphuretted hydrogen directly to
sulphurous acid I prefer, however, to treat it for the obtainment of its sulphur
in the free state by a former Invention for which Letters Patent, bearing date the
Thirty-first of July, 1871, and numbered 2008, have been granted to me.
To carry out the above stated method of obtaining phosphate and aluminate of
soda together with that method of treating the resulting sulphuretted hydrogen
which I believe to be the most advantageous, I employ a combination of appliances
the central element of which is a revolving furnace lined with blocks of carbon,
preferably though not necessarily, such as are produced by artificially agglomerating
coke under my Invention, the Letters Patent for which are numbered 3382 of the
year 1876
As required only for the conversion of sulphide of sodium into
phosphate and aluminate of soda, this furnace need differ from the revolving
furnaces at present in nearly general use among manufacturers of alkali only in
being lined with blocks of carbon instead of with fire-brick; but when the furnaco
is to be used not only for the conversion of sulphide of sodium into phosphate and
aluminate, as aforesaid, but also for the manufacture of the sulphide itself, it may
have likewise the further peculiarities which are described for a revolving furnace,
for the manufacture of alkaline sulphides in the Specification of my Patent,
numbered 3380, of the year 1876. With one end of the said carbon lined revolving
furnace I connect any suitable apparatus for the production of highly superheated
steam, which apparatus may conveniently be that which is known as the Siemens-
Cowper stove; and the other end of it I connect with such apparatus for the
treatinent together of a gas or gases and a liquid, as is described in the Specification
of my Patent numbered 3389 of the year 1876. To these appliances must be added
an "oxidizer," such as is used in my well-known process for the regeneration of the
manganese employed in the manufacture of chlorine.
The mode of working is as follows:-When the revolving furnace contains a
charge of sulphide of sodium which has either been produced therein, or having
been produced in other apparatus has been charged thereinto, such sulphide being
preferably in the state of fusion, I add thereto finely powdered phosphate of
alumina, and I then put the furnace in revolution and send into it a blast of highly
superheated steam. As long as steam is going into it I keep the furnace in
Jevolution, in order that the steam may come into contact with all parts of-its

page_text: contents. When sulphuretted hydrogen ceases to be evolved the entrance of the
steam is interrupted, and the charge having now become converted into a mixture
of phosphate and aluminate of soda is withdrawn from the furnace, and the furnace
is then recharged for a fresh operation.
The sulphuretted hydrogon, which is evolved during the operation just described,
passes on leaving the furnace into the first of a series of closed vessels or absorbers,
each of them partially filled with a mixture with water of finely divided oxide of
iron or of inanganese. Almost any oxide of either of these metals may be used
but I prefer to employ precipitated and therefore hydrated sesquioxide of iron.
Each vessel of the said series is furnished with a mechanical agitator consisting of
a number of arms attached at right angles to an axis or shaft placed horizontally,
and these agitators are so arranged and kept in such rapid notion as to maintain
in the upper part of each vessel a continual rain or spray of the mixture with water
of oxide of iron or other oxide, as aforesaid. The sulphuretted hydrogen enters tho
first vessel of the series at its upper part, and there comes into contact with an
enormous surface of the said rain or spray. It comes into contact at the same time
with the continually renewed surface of the mixture of metallic oxide and water
in the lower part of the vessel. Under these conditions much of the sulphuretted
hydrogen first dissolves in the water of the said mixture and then reacts on the
metallic oxide therein, its sulphur entering into combination with the metal of the
said oxide and its hydrogen with the oxygen thereof. That part of the sulphuretted
bydrogen which has not time thus to react upon the mixture of oxide and water
in the said first vessel, and thus to become absorbed in that vessel, passes on into
the upper part of the second vessel of the series where a further portion of it
reacts and thereby becomes absorbed, as aforesaid, what is not absorbed in this
second vessel passing on into the upper part of the next vessel of the series, and
BO on until every trace of the sulphuretted hydrogen has been absorbed.
If the size of the absorbers be properly adjusted to the size of the revolving
furnace and to the rate at which sulphuretted hydrogen is produced therein from
four to six absorbers will suffice for its completo absorption, but much will depend
in this respect upon the speed at which the agitators are worked. When the oxide
of iron or other oxide in the mixture thereof with water with which the first vessel
was charged has been completely converted into sulphide, the contents of that vessel
are withdrawn therefrom and the contents of the second vessel are transferred to
the said first vessol, those of the third vessel are transferred to the second vessel,
and so on throughout the series, the last vessel, when its contents have been
transferred to the last but one, being recharged with fresh mixture of oxide and
water The mixture of metallic sulphide with water, which has thus been with-
drawn from the first vessel of the series, is put into an "oxidizer" or deep cylindrical
vessel connected with a blowing engine by a pipe conveying air therefrom, which
pipe terminates near the bottom of the oxidizer in an arrangement of smaller pipes
or other suitable appliance for disseminating as thoroughly as possible through the
contents of the vessel the air which may be injected into it. Therein the said
mixture of metallic sulphide with water is treated by air until the sulphide in such
mixture is reconverted into oxide, its sulphur being at the same time set free. The
product of this operation is a mixture with water of metallic oxide and free sulphur.
This mixture can be used again for the absorption of more sulphuretted hydrogen
instead of fresh mixture of oxide and water, and with intermediate treatment by
air it can thus be employed several tames successively, becoming continually richer
and richer in sulphur. When it contains such proportion of sulphur as may be
preferred it may be treated by hydrochloric or other suitable acid, so as to dissolve
the oxide out from it, leaving free sulphur; or the mixture of oxide and free
sulphur may be separated from the water it is mixed with or suspended in and be
drained and dried, and may then have its sulphur burnt off from it as sulphurous
acid, as will be well understood. Applied in this last-mentioned manner the said
mixture gives sulphurous acid gas as little diluted as can be obtained by burning
the best brimstone, and far less dilute than that obtained by burning pyrites, seeing

page_text: that the sulphur in the said mixture is all in the free state and not combined, and
that the metal in the mixture is already fully oxidized, and so absorbs no oxygen
during the operation of burning off the sulphur.
Instead of performing in a revolving furnace, as aforesaid, the above-described
treatment by superheated steam of sulphide of sodium mixed with phosphate of
alumina, native or other, that treatment may be performed in other apparatus,
though I believe the revolving furnace to be best.
Another method of performing it consists in mixing the phosphate of alumina
with the sulphide of sodium while the latter is in the state of fusion, then allowing
the mixture to cool and solidify, and then breaking it up into small lumps, charging
these lumps into vertical cylinders and passing the steam through and among them,
as contained therein.
The treatment, as above described, of sulphide of sodium mixed with phosphate
of alumina may be modified by using a blast of highly heated air instead of super-
heated steam. This method yields directly as sulphurous acid the sulphur of so
much of the sulphide as becomes thereby converted into phosphate or aluminate;
but the sulphurous acid so obtained is extremely dilute, and much of the sulphide
instead of being enabled to react on phosphate of alumina becomes oxidized to
sulphate.
The proportions in which sulphide of sodium and phosphate of alumina must be
mixed together to be treated under the present Invention will necessarily vary, as
will be well understood, with the proportions of phosphoric acid and of alumina in
the phosphate of alumina used, and with the kind of phosphate of soda and the
kind of aluminate of soda which it is desired to produce Having ascertained the
composition of the phosphate of alumina which is to be employed I prefer to use
such a proportion of it as that the product of the treatment by steam of a mixture
thereof with sulphide of sodium shall be a mixture of tri-sodic phosphate and
tri-sodic aluminate
Having thus 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 herein-before in part recited Letters Patent,-
Firstly The new method or process for transforming sulphide of sodium into
phosphate and aluminate of soda, and sulphide of potassium into phosphate and
aluminate of potash, which is above described.
And, Secondly. The combination of processes and appliances whereby, sub-
stantially as is above set forth, I transform sulphide of sodium into phosphate and
aluminate of soda, and sulphide of potassium into phosphate and aluminate of
potash, and at the same time obtain the sulphur of the said sulphides either as free
sulphur or as sulphurous acid.
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.