IMPROVEMENTS IN OBTAINING SULPHUR FROM SULPHURETTED HYDROGEN, AND IN MANUFACTURING SODA AND POTASH
Year: 1871

page_text: LETTERS PATENT to Walter Weldon, of 29, The Cedars, Putney, in
the County of Surrey, for the Invention of "IMPROVEMENTS IN
OBTAINING SULPHUR FROM SULPHURETTED HYDROGEN, AND IN MANUFACTURING
SODA AND POTASH."
Sealed the 12th December 1871, and dated the 31st July 1871.
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the
Office of the Commissioners of Patents, with his Petition, on the
31st July 1871.
I, WALTER WELDON, of 29, The Cedars, Putney, in the County of
Surrey, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN OBTAINING SULPHUR FROM SULPHURETTED HYDROGEN, AND IN MANU-
FACTURING SODA AND POTASH," to be as follows:-
This Invention consists in a new method of obtaining sulphur from
sulphuretted hydrogen, and in a combination of processes for the
application of this method to the recovery of the sulphur employed in
the manufacture of soda and potash from the chlorides of sodium and
potassium.

page_text: To obtain free sulphur from sulphuretted hydrogen under the present
Invention I pass the sulphuretted hydrogen into water in which is
suspended either oxide of iron or oxide of manganese. The metallic
oxide decomposes the sulphuretted hydrogen, forming water, and either
a metallic sulphide only, or both a metallic sulphide and free sulphur.
I then treat this product with atmospheric air (preferably by injection
thereof), whereby the metallic sulphide is transformed into oxide and
its sulphur is set free. I have found that this method of bringing
sulphuretted hydrogen into contact with a metallic oxide, and of
bringing air into contact with the resulting metallic sulphide, gives
far better results than any method hitherto employed. A single
treatment first with sulphuretted hydrogen and then with air, may
sometimes suffice; but into the mixture of metallic oxide and free
sulphur so obtained I prefer to pass more sulphuretted hydrogen. I
then treat with air as before, and then again with sulphuretted
hydrogen, repeating these alternate treatments first with sulphuretted
bydrogen and then with air until I have obtained a mixture of sulphur
and metallic oxide containing a considerable proportion of the former.
It is easy to obtain such a mixture containing more than twenty parts
of free sulphur to one of oxide. When the proportion of sulphur in the
said mixture has become sufficient I prefer to dissolve out the metallic
oxide by any suitable acid, leaving the sulphur almost entirely free
from other bodies; but I can also either distill off the sulphur, or burn
it off as sulphurous acid, or separate it by fusion and liquation.
In applying the above described process to the recovery of the
sulphur employed in the manufacture of soda and potash from the
chlorides of sodium and potassium, I prefer to employ a combination of
processes, whereby I first transform the chloride of sodium or potassium
into sulphate, then transform this sulphate into sulphide, and then
decompose this sulphide by carbonic acid, obtaining by this third
operation carbonate of alkali metal and sulphuretted hydrogen, which
last body I treat as above set forth. I can also proceed by simply
decomposing either by any convenient acid or by steam the waste
product of those manufactures as at present conducted, and treating the
resulting sulphuretted hydrogen as aforesaid.
The carbonic acid employed as above may be from any source, but
that obtained by the careful combustion of carbonaceous fuel will
usually be the most advantageous. The body which it is employed to

page_text: "
decompose should be contained in a closed vessel, or in several closed
vessels so connected together that the gases which pass off from the
first vessel of the series shall pass through the contents of the second
vessel, and the gases which pass off from the second vessel through the
contents of the third vessel, and so on. When the body which the
carbonic acid is employed to decompose is either sulphide of sodium
or sulphide of potassium, I prefer that such body should be in solution
in water; and when it is either the present "soda waste' or any other
similar body, I prefer that it should be in admixture with water. I
prefer that the mixture which is to decompose the sulphuretted
hydrogen should likewise be contained in several vessels, so arranged
that the gases which pass off from one vessel shall pass through the
contents of the next, and moreover so arranged that the order in which
the sulphuretted hydrogen or the mixture of gases at first containing
sulphuretted hydrogen shall enter and pass through the various vessels
can be changed at will. Into the vessel into which the sulphuretted
hydrogen, or mixture of gases containing sulphuretted hydrogen,
first passes, I prefer to send an excess of sulphuretted hydrogen, so as
to secure that the whole of the metallic oxide contained in that vessel
shall be acted upon. I then secure the decomposition of the whole of
the sulphuretted hydrogen which passes over from this first vessel by
sending it through or into other vessels containing an excess of metallic
oxide. Each of these latter vessels successively I prefer to make in
its turn the first of the series, treating its contents with an excess of
sulphuretted hydrogen, and sending the sulphuretted hydrogen which
passes off from it into an excess of metallic oxide, as before. I prefer
to commence with hydrated oxide of iron or oxide of manganese,
although it is not always essential that the oxide should be hydrated.
Finally, instead of treating the mixture which is employed to decompose
the sulphuretted hydrogen first with the sulphuretted hydrogen and
then with air, one may treat it with both simultaneously.
I have above described what I conceive to be the most important
application of the new method of obtaining sulphur from sulphuretted
hydrogen which is above set forth, but the said method is applicable
also to sulphuretted hydrogen obtained or produced in any other way,
and whether in the free state or in the nascent state. Good results may .
be obtained, without the sulphuretted hydrogen ever passing beyond
the nascent condition, by adding oxide of iron or oxide of manganese to

page_text: solution of sulphite of sodium or potassium, and treating the resulting
mixture with carbonic acid. It is thereby converted into solution of
carbonate of soda or of potash holding in suspension a metallic sulphide,
which last may be converted as above into a mixture of oxide and free
sulphur, ready for use again.
on the 22nd January 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WALTER
WELDON, of 29, The Cedars, Putney, in the County of Surrey, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirty-first day of July, in the year of
our Lord One thousand eight hundred and seventy-one, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Walter Weldon, Her special licence that I,
the said Walter Weldon, my executors, administrators, and assigns, or
such others as I, the said Walter Weldon, executors, administrators,
and assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for "IMPROVEMENTS IN OBTAINING SULPHUR
FROM SULPHURETTED HYDROGEN, AND IN MANUFACTURING SODA AND POTASH," upon
the condition (amongst others) that I, the said Walter Weldon, my
executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the
Great Seal Patent Office within six calendar months next and imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Walter Weldon, do hereby declare
the nature of my said Invention and in what manner the same is to be

page_text: performed, to be particularly described and ascertained in and by the
following statement :-
This Invention consists in a new method of obtaining free sulphur
from sulphuretted hydrogen, whatever the manner or method by which
the sulphuretted hydrogen may have been produced, or whatever the
source from which it may have been obtained or derived, and in a com-
bination of processes for the application of this method to the recovery
of the sulphur employed in the manufacture of soda and potash.
To obtain free sulphur from sulphuretted hydrogen under my said
Invention the sulphuretted hydrogen is brought into intimate contact
with water, in which is suspended or diffused either oxide of iron or
oxide of manganese, and the product which results is then submitted
to the action of air. The metallic oxide decomposes the sulphuretted
hydrogen, forming water and either free sulphur and a metallic sulphide
or a metallic sulphide only; and the oxygen of the air then substitutes
itself for the sulphur in this sulphide, setting the sulphur free and
reproducing an oxide available for use as before. There is thus obtained
a mixture with water of free sulphur and metallic oxide, and if the
operator chooses he may stop at this point, separating his sulphur
from his metallic oxide by any convenient means; but I prefer that the
said mixture should be treated with more sulphuretted hydrogen, and
then the product with more air, and that this alternate treatment, first
with sulphuretted hydrogen and then with air, should be repeated time
after time until a mixture has been obtained containing a much larger
proportion of free sulphur than of metallic oxide. The metallic oxide
may then be dissolved out by means of any convenient acid, or the
sulphur may be dissolved out by any available solvent thereof, or the
sulphur may be either distilled off or separated by fusion and liquation,
or burnt off as sulphurous acid.
In performing my said Invention I prefer to employ a series of two
or more closed vessels, into each of which enters a pipe or pipes by
which to inject and convey to near the bottom of the vessel either air or
sulphuretted hydrogen, or a mixture of sulphuretted hydrogen and other
gas or gases, as the case may be. Each of these pipes should preferably
terminate in some such arrangement for the distribution of the gas or
gases over the bottom of the vessel as the "oxidizes" used in my
process for the regeneration in the wet way of compounds of manganese
employed in the manufacture of chlorine are furnished with. The

page_text: several vessels should be so connected together that whatever portion of
any gas injected into the first vessel is not absorbed by the contents of
that vessel shall pass off from that vessel into and down to near the
bottom of the contents of the second vessel, and that if more than two
vessels be employed whatever is not absorbed by the contents of the
second vessel shall pass off from that vessel into and down near to
the bottom of the contents of the third vessel, and so on. The apparatus
being thus arranged, and each of the vessels included in it being charged
to a suitable depth with water having diffused or suspended in it a
metallic oxide as aforesaid, sulphuretted hydrogen, or a mixture of
sulphuretted hydrogen and other gas or gases, is injected into the first
vessel of the series and preferably in quantity somewhat in excess of
the quantity chemically equivalent to the quantity of metallic oxide
contained in that vessel. The metallic oxide contained in the said first
vessel of the series is thereby completely transformed into sulphide,
and what sulphuretted hydrogen passes over from that vessel meets with
such an excess of metallic oxide in the subsequent vessel or vessels as
to secure that from the final vessel of the series no trace of undecom-
posed sulphuretted hydrogen can escape. When the oxide in the first
vessel has been sufficiently treated with sulphuretted hydrogen this
vessel is disconnected from the other vessel or vessels, and air is then
injected into its contents until the oxide which the sulphuretted
hydrogen had transformed into sulphide is converted into oxide again.
The vessel is then re-connected with the other vessel or vessels, but
preferably in such manner that it shall now be the last vessel of the
series, that which before was the second vessel being now the first.
From this point all is repeated, and it is then repeated again time after
time until sulphur has so accumulated that it must be removed and the
series of operations re-commenced.
The state of oxidation of the oxide of iron or of manganese with
which the series of operations is begun is not important, nor need the
oxide be necessarily a hydrated one. I greatly prefer however to begin
with a hydrated oxide in a very fine state of division, such as is obtained
by precipitating either by lime, by magnesia, or by an alkali a solution
of the metal whose oxide is employed.
I am aware that the treatment of oxide of iron by sulphuretted
hydrogen and atmospheric air alternately is already commonly practised
in the manufacture of coal gas; but the process is a wholly different

page_text: one from that described above, the oxide of iron being employed not in
suspension in water but in lumps or powder spread on trays and under
conditions under which its particles are wholly immobile, and the sul-
phuretted hydrogen being presented to it in the state of gas. The
method which is thus employed for the purification of coal gas from
the small quantity of sulphuretted hydrogen originally contained
therein, and which is successful enough as applied to that object, has
been found wholly inadequate to the treatment of sulphuretted hydrogen
when produced in very large quantities and in a comparatively undiluted
state. In all attempts to deal by that method with large quantities of
strong sulphuretted hydrogen a large proportion of the sulphuretted
hydrogen has escaped decomposition, and owing to the high temperature
which is developed by the reaction of but slightly diluted sulphuretted
hydrogen upon any oxide of iron, whether hydrated or anhydrous, the
product of the decomposition of such portion of it as has been decom-
posed has been an altogether different one from that which results from
the reaction of very dilute sulphuretted hydrogen upon oxide of iron in
coal gas purifiers.
It has been an anhydrous sulphide of iron, or artificial pyrites, from
which free sulphur could not be liberated by treatment with air, and
the value of which was not half that which the sulphur contained in it
would have had in the free state. In my process above described it
is not gascous sulphuretted hydrogen but a solution of sulphuretted
bydrogen in water which is presented to the metallic oxide, and the
metallic oxide is under such conditions of mobility and of perpetual
change of position on the part of each of its particles that every one of
the said particles is made to present its full surface to the solution, and
not one of them has any chance of escaping the performance of the
work it is there to do. My present Invention thus affords for the first
time a means of completely decomposing sulphuretted hydrogen, strong
or dilute, with such facility as to admit of its being dealt with in any
quantity, and at the same time of so decomposing it as to obtain its
sulphur free.
In applying my said Invention to the recovery of the sulphur em-
ployed in the manufacture of soda and potash I prefer to use a com-
bination of processes whereby chloride of sodium or potassium is
transformed either directly or indirectly into sulphide, and this sulphide
is decomposed by carbonic acid, yielding carbonate of soda or of potash.

page_text: and sulphuretted hydrogen, which last body is then treated by my
process as above described; or I add to solution of sulphide of sodium
or of potassium, either oxide of iron or oxide of manganese, and
then treat first with carbonic acid and then with air, whereby there is
obtained a solution of carbonate of soda or of potash and a mixture of
metallic oxide and free sulphur which can be used again instead of fresh
oxide.
While my said Invention is applicable to sulphuretted hydrogen from
any source and whatever the process in which or the method by which
it may have been produced I would indicate as valuable applications of
it in addition to the recovery of the sulphur employed in the manfacture
of soda and potash the obtainment of sulphur from the sulphuretted
hydrogen produced by treating the residue known as "alkali waste"
by either acids or steam from that produced in the manufacture of
certain ammoniacal salts and from that produced in the manufacture of
oxychloride of lead from galena.
The method of performing my said Invention which is described
above may be modified in either, or any, or all of the following
ways:-
(1.) The metallic oxide may be suspended or diffused in an alkaline
or saline solution instead of in water only.
(2.) The sulphuretted hydrogen and air may be brought into the
required intimate contact with the mixture containing the metallic
oxide or metallic sulphide otherwise than by the method of injection.
(3.) The treatment with the sulphuretted hydrogen and the treatment
with air instead of being alternate and successive may be simultaneous.
And (4). When the treatment with sulphuretted hydrogen and air is
by injection first of one and then of the other, and an apparatus is
employed consisting of several vessels, as above described, instead of
disconnecting the first vessel from time to time and injecting air into
it only, the several vessels may remain always connected and may
preserve always the same respective positions in the series, the treat-
ment with air being always made by injecting it into the first vessel, as
much of the air as is not absorbed in the first vessel then passing off
from that vessel and down to near the bottom of the contents of the
next vessel, and so on to the end of the series, the portion of the injected
air which remains finally unabsorbed escaping from the last vessel into
the atmosphere.

page_text: And now having described 'and particularly ascertained the nature of
my said Invention, and in what manner the same is to be performed, I
declare that I do not claim as my Invention the above-described process
for the manufacture of soda and potash, except in so far as it includes
and is combined with my new method of obtaining free sulphur from
free or nascent sulphuretted hydrogen; but that what I do claim as my
Invention and desire to be secured to me by the herein-before in part
recited Letters Patent is,-
Firstly. Obtaining free sulphur from sulphuretted hydrogen, substan-
stantially as is above described.
And, secondly. The combination of processes above set forth for
applying my new method of obtaining sulphur from sulphuretted
hydrogen to the recovery of the sulphur employed in the manufacture
of soda and potash.
In witness whereof, I, the said Walter Weldon, have hereunto set
my hand and scal, this Nineteenth day of January, in the year
of our Lord One thousand eight hundred and seventy-two.
זA1ד HTT
WALTER WELDON.
WELDON. (L.S.)