Improvements in and in connection with the Desulphurisation of Sulphuretted Hydrogen.
Year: 1899

page_text: PROVISIONAL DITUITIVATION.
Improvements in and in connection with the Desulphurisation of
Sulphuretted Hydrogen.
I, HENRY WILLIAM HEMINGWAY, of Allyns, Forest Road, Walthamstow, in the
County of Essex, Manufacturer, do hereby declare the nature of this invention
to be as follows:
:-
This invention relates to the treatment of sulphuretted hydrogen, or gases con-
taining sulphuretted hydrogen, with a view to the elimination and recovery of
the sulphur, and incidentally to the manufacture of sulphite of iron, sulphate of
ammonia and other useful products.
In treating the waste and noxious gases which are evolved in the manufacture
of sulphate of ammonia and in certain other processes, and which consist for
the greater part of sulphuretted hydrogen and carbonic acid, I proceed as follows:
I take a portion of the sulphuretted hydrogen gas, and, by burning, convert it
into sulphurous acid by any of the well-known methods; or (for the purpose of
carrying out one part of my invention without the other part) I may burn sulphur
or sulphide of iron; or I may take the gas from a pyrites kiln. The sulphurous
acid gas (however obtained) is led into a tower packed with flint, stone, brick,
coke or other suitable material, a suitable quantity of ammonia gas, obtained from
sulphate of ammonia apparatus or other available source of supply being, at the
same time admitted. The sulphurous acid and ammonia gases on mixing form
sulphite of ammonia, which, with the aid of a small quantity of water, is washed
down the tower. To the solution of sulphite of ammonia, I add ferrous sulphate,
sulphite of iron and sulphate of ammonia resulting. If it be desired to obtain
all the sulphite of iron as well as the sulphate of ammonia in a fluid condition
the mixture should be slightly acid. Or instead of washing down the sulphite of
ammonia with water, a solution of ferrous sulphate may be employed and the
mixture of sulphite of iron and sulphate of ammonia directly produced.
Into a second tower, or other vessel adapted for effecting the intermingling of
gases, I lead the noxious gases containing sulphuretted hydrogen; and down this
tower, I rain the solution of sulphite of iron and sulphate of ammonia yielded by
the tower first referred to. Or the sulphuretted hydrogen gas may be forced into
a vessel charged with the mixture of sulphite and sulphate. In either case part
of the sulphuretted hydrogen reacts with the combined sulphurous acid and
forms free sulphur, whilst a further part of the sulphuretted hydrogen unites
with the iron and forms sulphide of iron. Both of these products being solids,
the solution of sulphate of ammonia can be filtered off and run into the saturator
ordinarily employed in the manufacture of sulphate of ammonia.
It will be observed that with two equivalents of ferrous sulphite, I recover two
equivalents of sulphur in combination with iron and six equivalents of free sul-
phur unless, as sometimes happens, some small-quantity of the sulphur forms

page_text: penta-thionic acid. These may be decomposed by adding scrap iron and turning
the sulphuretted hydrogen, so set at liberty, into the tower; sulphide of iron
resulting.
Instead of taking the mixture of sulphite of iron and sulphate of ammonia and
exposing the same to the influence of sulphuretted hydrogen as hereinbefore
described, I may separate the solid sulphite of iron by subsidence, filtration, or.
other known means, from the sulphate of ammonia and then use the former in a
manner similar to that in which hydrated peroxide of iron is used in the purifica-
tion of coal-gas. Or the sulphite of iron may be mixed with water and reduced
to such a consistency that it will flow down a tower, the filtrate of sulphate of
ammonia having been used separately: Little advantage is however gained by
the early separation of the sulphate of ammonia; it being more easily separated
from the iron after the treatment with sulphuretted hydrogen.
It will also be observed that no waste takes place. The sulphur contained in
the sulphuretted hydrogen is recovered, as also that contained in the sulphurous
acid and in the ferrous sulphate; and all the ammonia is returned.
In treating sulphuretted hydrogen in the recovery of sulphur from tank ash or
soda waste, I take a solution of soda' ash, instead of ammonia, and I rain this
down the tower, through which sulphurous acid is passing, sulphite of soda
resulting. Or I take sulphite of soda produced in any other manner, add ferrous
sulphate, as in the process first described, and form sulphate of soda and sulphite
of iron. I expose these to the action of sulphuretted hydrogen as before; using
the sulphite and sulphate together, or separating the sulphite of iron first. In
any case, the sulphate of soda can be used as such, so that no waste occurs; but in
the event of the sulphite of iron being separated from either the sulphate of
soda (or of ammonia) before the treatment with the sulphuretted hydrogen, it is
expedient to have a slight excess of sulphite of soda (or sulphite of ammonia) in
order to precipitate all the iron; after which the application of heat or the
addition of sulphuric acid will drive off the excess of sulphurous acid.
It is well known that sulphuretted hydrogen and sulphurous acid in the propor-
tion of two volumes of the former to one of the latter form water sulphur and
penta-thionic acids; and I adopt this method for obtaining as much sulphur as
possible, using the process above described as a final operation for taking up all
the sulphuretted hydrogen; the latter being supplied in excess of the sulphurous
acid. Instead however of employing the first chamber in which the sulphuretted
hydrogen and sulphurous acid meet one another, these gases may be passed at
once through the tower to which the sulphite of iron and sulphate of ammonia
(or of soda) are supplied.
In the purification of coal gas, in order to eliminate the sulphuretted hydrogen
I use sulphite of iron as previously described, either alone or mixed with saw-
dust or other porous materials, and employ an ordinary purifier. Or I pass the
sulphite of iron down a scrubber in which it meets the gas containing sulphuretted
hydrogen. In either case, the sulphuretted hydrogen is absorbed with great
rapidity, and only a small amount of sulphite of iron is needed to act upon
and absorb a large amount of sulphur.
In practice, I prefer to use sulphite of iron; but sulphite of copper, zine or
certain other metals, can be used. In some cases, particularly where the sulphides
of the metals are of value for special purposes, the employment of these metals
is preferable to that of iron; but the processes are the same. Moreover, although
in order to produce sulphites, I commence with or incidentally produce and
employ the sulphates of the metals, I can proceed in the same manner, using
chlorides when chlorides of ammonia, or of soda will be produced.
The sulphide of iron resulting from the process herein before described would be
available for the manufacture of sulphuric acid; and, being a precipitated iron
would when burnt furnish a valuable pigment. Or it may be mixed with green
copperas, concentrated and roasted, the sulphurous acid evolved in the latter opera-

page_text: tion being utilised in the manufacture of further quantities of sulphites of
alkalies or of alkaline earths.
"
Dated this 4th day of May 1899.
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"
...
Improvements in and in connection with the Desulphurisation of
Sulphuretted Hydrogen:
I, HENRY WILLIAM HEMINGWAY, of Allyns, Forest Road, Walthamstow, in the
County of Essex, Manufacturer, 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: -
This invention relates to the treatment of sulphuretted hydrogen or gases con-
taining sulphuretted hydrogen with a view to the elimination and recovery of
the sulphur, and incidentally to the manufacture of sulphite of iron, sulphate of
ammonia and other useful products.
In treating the waste and noxious gases which are evolved in the manufacture
of sulphate of ammonia and in certain other processes, and which consist for the
greater part of sulphuretted hydrogen, I proceed as follows:-I take a portion
of the sulphuretted hydrogen gas, and, by burning, convert it into sulphurous
acid by any of the well-known methods; or (for the purpose of carrying out one
part of my invention without the other part) I may burn sulphur or sulphide of
iron; or I may take the gas from a pyrites kiln. The sulphurous acid gas. is led
for example into a tower packed with flint, stone, brick, coke or other suitable
material, a suitable quantity of ammoniacal gas or ammonia being at the same
time admitted. The sulphurous acid and ammoniacal gases on mixing form sulphite
of ammonia, which, with the aid of a small quantity of water, is washed down
the tower. To the solution of sulphite of ammonia I add ferrous sulphate; sul-
phite of iron and sulphate of ammonia resulting. If it be desired to obtain all
the sulphite of iron as well as the sulphate of ammonia in a fluid condition, the
mixture should be rendered acid by the addition of a sufficient supply of sul-
phurous acid. Or instead of washing down the sulphite of ammonia with water,
a solution of ferrous sulphate may be employed and the mixture of sulphite of
iron and sulphate of ammonia directly produced.
Into a second tower, or other vessel adapted for effecting the intermingling of
gases, I lead the noxious gases containing sulphuretted hydrogen; and down. this
tower, I rain the solution of sulphite of iron and sulphate of ammonia yielded by.
the tower first referred to. Or the sulphuretted hydrogen gas may be forced into
a vessel charged with the said mixture of sulphite and sulphate. In either case,
part of the sulphuretted hydrogen reacts with the combined sulphurous acid and
forms free sulphur; whilst a further part of the sulphuretted hydrogen reacts and
forms sulphide of iron. Both of these products being solids, the solution of sul-
phate of ammonia can be filtered off and run into the saturator ordinarily employed
in the manufacture of sulphate of ammonia or otherwise dealt with.
It will be observed that with two equivalents of ferrous sulphate (subsequently
formed into sulphite) I recover two equivalents of sulphur in combination with
iron and six equivalents of free sulphur; unless, as sometimes happens, some
small quantity of the sulphur is converted into a thionic acid..

page_text: Instead of taking the mixture of sulphite of iron and sulphate of ammonia and
exposing the same to the influence of sulphuretted hydrogen as hereinbefore
described, I may separate the solid sulphite of iron by subsidence, filtration, or
other known means, from the sulphate of ammonia and then. use, the former. in a
manner similar to that in which hydrated peroxide of iron is used in the purifi-
cation of coal-gas. Or the sulphite of iron may be mixed with water, reduced
to such a consistency that it will flow, down a tower and thus be rendered service-
able, for the absorption of sulphuretted hydrogen as herein before.described.
It will also be observed that waste is avoided. The sulphur contained in the
sulphuretted hydrogen is recovered, as also that contained in the sulphurous acid
and in the ferrous sulphate; whilst the ammonia is returned.
In treating sulphuretted hydrogen evolved in the treatment of tank ash or soda
waste, for the recovery of sulphur or in the production of salts from the alkaline
sulphates, I take a solution of soda-ash, instead of ammonia, and I rain this down
the tower through which sulphurous acid is passing, sulphite of soda -resulting.
Or I take sulphite of soda produced in any other manner, or other sulphite of
an alkaline earth, add ferrous sulphate, as in the process first described, and form
sulphate of soda and sulphite of iron. I expose these to the action of sulphuretted
hydrogen as before; using the sulphite and sulphate together, or I separate the
sulphite of iron first. In any case, the sulphate of soda can be used as such, so that
waste is avoided; but in the event of the sulphite of iron being separated from
the sulphate of soda (or of ammonia) before the treatment with the sulphuretted
hydrogen, it is expedient to have a slight excess of sulphite of soda (or sulphite
of ammonia) in order to precipitate all the iron; after which the application of
heat or the addition of sulphuric acid will drive off the excess of sulphurous acid.
It is well known that sulphuretted hydrogen and sulphurous acid in the pro-
portion of two volumes of the former to one of the latter form water, sulphur and
penta-thionic acid; and I adopt, this method for obtaining as much sulphur as
possible, using the process above described as a final operation for taking up all
the sulphuretted hydrogen; the latter being supplied in excess of the sulphurous
acid. Instead however of employing the first chamber in which the sulphuretted
hydrogen and sulphurous acid meet one another, these gases may be passed at
once through the tower to which the sulphite of iron and sulphate of ammonia (or
of soda) are supplied. If it be also desired to recover the sulphur from the
thionic acids, the latter may be decomposed by adding scrap iron and turning the
sulphuretted hydrogen, so set at liberty, into the tower; sulphide of iron resulting.
In the purification of coal-gas, in order to eliminate the sulphuretted hydrogen,
I use sulphite of iron as previously described, either alone or mixed with sawdust
or other porous materials, and employ an ordinary purifier. Or I expose the
sulphite of iron in a scrubber to the action of the gas containing sulphuretted
hydrogen. In either case, the sulphuretted hydrogen is absorbed with great
rapidity, and only a small amount of sulphite of iron is needed to act upon and
absorb a large amount of sulphur.
:
In practice I prefer to use sulphite of iron; but sulphite of copper, zinc or
certain other metals, can be employed. In some cases, particularly where the
sulphides of the metals are of value for special purposes, the employment of these
metals is preferable to that of iron; but the processes are substantially the same.
Moreover although in order to produce sulphites, I commence with or incidentally
produce and employ the sulphates of the metals, I can proceed in the same manner,
using chlorides when chlorides of ammonia or of soda will be produced.
The sulphide of iron resulting from the process hereinbefore described would
be available for the manufacture of sulphuric acid; and, being a precipitate,
would when burnt furnish a valuable pigment. Or it may be mixed with green
copperas, concentrated and roasted, the sulphurous acid evolved in the latter
operation being utilised in the manufacture of further quantities of sulphites of
alkalies or of alkaline earths.
In the drawing appended hereto is illustrated a plant or series of appliances

page_text: adapted for carrying my improved process for the desulphurisation of sulphuretted
hydrogen into effect.
The sulphuretted hydrogen, or gas containing sulphuretted hydrogen, arrives
by the pipe A. A portion is conducted to the furnace B, whence it escapes, in
the form of sulphurous acid, by way of the pipe b, to the tower or scrubber C.
Ammonia or animoniacal gas, which arrives by the pipe D, is led to the upper
portion of the tower C. The coke or like porous material, wherewith the tower: C
is charged, is traversed by a stream of water which enters by the pipe E; the
sulphite of ammonia being thus washed down as it is formed, and flowing, by way
of the pipe c, to the tank F. The surplus sulphurous acid is led by the pipe.c
to another tower H, the function of which will be referred to later. The tank G
contains a solution of sulphate of iron, a regulated supply of which is delivered by
way of the pipe g to the tank F. Upon the sulphate of iron mingling with the
sulphite of ammonia reactions take place which result in the production of a
mixture of sulphite of iron and sulphate of ammonia. This mixture passes by the
pipe to the pump J, and thence to the tank K, whence it is delivered to a
third tower L.This tower is furnished with coke or like material (preferably
carried on perforated trays arranged at intervals) through which the liquid
mixture passes; sulphuretted hydrogen, admitted at the lower part of the tower
by the pipe h, passing in the opposite direction. is a device of the bascule type
for distributing the mixture of sulphite and sulphate over the porous material
carried by the perforated trays . In this tower, sulphide of iron and free sul-
phur are deposited as solids, whilst a solution of sulphate of ammonia overflows.
by the pipe from the tank to the tank or conduit
Returning now to the tower H, sulphuretted hydrogen enters by the pipe a,
whilst sulphurous acid enters by the pipe c¹. A portion of the sulphuretted
hydrogen combines with the sulphurous acid, or with a portion thereof, with the
result that water and thionic acids are formed and free sulphur deposited. The
water and acid escape by the pipe to the tank M which is charged with scrap
iron. The thionic acids are here decomposed, sulphide of iron being formed,
whilst sulphuretted hydrogen is liberated. The latter escapes by the pipe 2 and
returns to the tower H.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed; 1 claim:-
1. The herein described process for the desulphurisation of sulphuretted hydro-
gen, consisting in converting a portion of the said gas into sulphurous acid, adding
ammonia thereto and thus forming sulphite of ammonia, adding to the latter
ferrous sulphate and thus producing sulphite of iron and sulphate of ammonia
and then passing this mixture through a scrubber or equivalent apparatus, whilst
another portion of the sulphuretted hydrogen passes in the opposite direction, the
reactions which thereupon ensue resulting in the production of sulphide of iron
and free sulphur as solid deposits and sulphate of ammonia as a solution..
2. The herein described modification of the process referred to in the preceding
claiming clause, which consists in separating the sulphite of iron from the sul-
phate of ammonia, employing the former in the desulphurisation of sulphuretted
hydrogen and leaving the latter available for any of the purposes for which sul-
phate of ammonia is applicable.
3. The further modification of the said process in order to adapt it to the
recovery of sulphur in the treatment of tank-ash or soda waste or in the produc-
tion of salts from the alkaline sulphates, consisting in exposing a solution of soda-
ash in a scrubber or equivalent apparatus to the action of sulphurous acid, pro-
ducing sulphite of soda, mixing the same with sulphate of iron with a view to the
production of sulphite of iron and sulphate of soda, and employing the sulphite
of iron in the desulphurisation of sulphuretted hydrogen.
4. In the purification of coal-gas or in the desulphurisation of other gas con-

page_text: taining sulphuretted hydrogen, the employment of sulphite of iron, of copper,
or of zinc, either alone or mixed with sawdust or other suitable material, sub-
stantially as herein described.
5. The modification of the process referred to in the preceding claiming clause,
in order to adapt it to the production of chlorides of the alkalies or alkaline
earths, consisting in substituting chloride of iron, of copper, or of zinc, for the
sulphate prior to its conversion to a sulphite, chloride of ammonium of soda, or
of the other alkali or alkaline earth employed resulting.
6. In the purification of coal-gas or in the desulphurisation of other gas con-
taining sulphuretted hydrogen, the employment of sulphite of iron, of copper,
or of zinc substantially as herein described.
7. The desulphurisation of sulphuretted hydrogen and the production of sul-
phite of iron and sulphate of ammonia, by converting said gas into sulphurous
acid adding ammonia thereto and thus forming sulphite of ammonia, adding to
the latter ferrous sulphate, and then separating, by means of filtration or other-
wise, the sulphite of iron from the sulphate of ammonia yielded.
8. In the decomposition of acids of the thionic group, the employment of
scrap-iron, substantially as herein described; sulphuretted hydrogen being liber-
ated for further treatment in the manner herein described, and sulphide of the
metal employed being obtained.
Dated this 23rd day of January 1900.
For the Applicant,
G. G. M. HARDINGHAM,
Chartered Patent Agent, Clun House, Surrey Street, London, W.C.