IMPROVEMENTS IN AND IN APPARATUS FOR OBTAINING SULPHUR AND BOME OF ITS COMPOUNDS AND IN THE TREATMENT THEREOF AND ALSO OF THE ASSOCIATED PRODUCTS "
Year: 1882

page_text: LETTERS PATENT to Francis Bristow Rawes of Stratford in the county of
Essex for an invention of "IMPROVEMENTS IN AND IN APPARATUS FOR
OBTAINING SULPHUR AND BOME OF ITS COMPOUNDS AND IN THE TREATMENT
THEREOF AND ALSO OF THE ASSOCIATED PRODUCTS
"
PROVISIONAL SPECIFICATION laft by the said Francis Bristow Rawes a
the Office of the Commissioners of Patents on the 22nd March 1882.
IMPROVEMENTS
- FRANOIS BRISTOW RAWES of Stratford in the County of Essex
IN AND IN APPARATUB FOR OBTAINING SULPHUR AND SOME OF ITS COMPOUNDS
AND IN THE TREATMENT THEREOF AND ALSO OF THE ASSOCIATED PRODUCTS,"
There are several compounds both natural and artificial, of sulphur with bases
such as gypsum, sulphate of lime, heavy spar, alkali waste, and many others to
which the processes hereinafter described or some of them are applicable as will be
well understood by chemists, reference is made, however, more particularly to
compounds of sulphur with lime (calcium) as a base they being generally more
abundant and available, at the same time including other such bases in combination
with sulphur to which this invention can be applied.
If the compound be a sulphate (gypsum for instance) or in any other state of
combination than that of sulphide and capable of being reduced to the state of
sulphide. I first reduce it to that state (of sulphide) by any known process for
instance in the case of gypsum pulverising and intimately mixing it with carbon
(coal or otherwise) in the proportions of 30 parts carbon or a little in axcess thereof
which is desirable to every 100 parts of gypsum and then strongly heating the
mixture in a crucible or a retort or other suitable apparatus for 2 or 8 hours or
longer if the quantity operated upon being large requires it in order that the heat
may permeate the whole mass.
If the compounds operated upon contain any material other than sulphur
and its combined base or bases (calcium or otherwise) such as any accidental or

page_text: occasional admixture or as is ordinarily incident to natural minerals if it b
desirable to separate it because of its value or its detrimental presence, I obtain
solution from the crude compound (sulphide) in any suitablo menstruum-hydro
chloric acid for instance and according to what may happen to he present in the
compound in any known manner obtain and utilize the bye products, recovering
the base (lime or otherwise) as sulphate by the well known reaction of sulphuric
acid collecting in the usual manner and utilizing the hydrochloric acid driven off
The sulphate may then be treated as specified in the preceding paragraph.
Calcium chloride a bye product in many chemical operations may be similarly
converted (by sulphuric acid) into sulphate of lime and then be treated as other
sulphates.
To displace the sulphur from combination with its base (calcium or otherwise) I
employ carbon dioxide (carbonic acid) conjointly with an intermedium as a contact
agent and agitation to bring successive particles of the sulphide (in powder in a
suitable vessel) within the influence of the reactions of the carbon dioxide and the
intermedium. The reaction of carbon dioxide upon sulphides is well known but
the use of an intermedium and the employment of agitation (which latter may be
caused by the gas being driven in with sufficient force or by the use of any kind of
commotion from a mechanical stirrer or otherwise) are important aids to the
operation of the affinities bringing the comparatively dense sulphide-molecule by
molecule as it were-into contact with the carbon dioxide gas liberating hydrogen
sulphide and they (intermedium and agitation) are essential features of this invention
as without either one of them the reaction of carbon dioxide gus upon a dry sulphide
is difficult, imperfect and only slightly partial. As intermedium I preferably use
an alkali (as soda) carbonated or supercarbonated and in solution to exclude
atmospheric air, and it is better if the water has been previously boiled to the
intent that the oxidation of the sulphur should be as much as possible avoided.
The carbon dioxide (C O₂) may be obtained from any source and particularly
from lime kilns or from the combustion of fuel or from both, a sufficient access of air
having been provided to prevent the presence of carbon monoxide (CO) instead of
carbon dioxide any excess of oxygen as far as it is practicable being absorbed
afterwards in any suitable manner preferably by protoxide of iron the resulting
peroxide of iron being afterwards reduced to protoxide by hydrogen sulphide
similar to the processes used at gas works or by any other process and it will be
well by a little attention to the admission of air to the fuel and management by
control of a damper or the like to regulate the supply of air to the fires so that
the excess of oxygen supplied in the air may be easily reduced to a minimum
afterwards. The heat of the gases of combustion may be utilized in cooling them
down to about the temperature of the atmosphere.
"
"
As an abundance of carbon dioxide can be obtained at a cheap rate, in some
cases it may be convenient to have a prepared supply of alkali snpercarbonated and
so use the requisite quantity of carbon dioxide in a combined form (with the alkali
intermedium) applied to the " sulphide with agitation and sufficient water to
exclude the air and prevent oxidation. For instance instead of presenting the
carbon dioxide in the state of gas to the " sulphide and intermedium for the
reactions I may use it in combination with the alkaline intermedium thus to every
72 parts of calcium sulphide (or for other sulphide in the quantity of its chemical
equivalent) take 168 parts of bicarbonate of soda (if that be the intermedium alkali
used) with agitation in a suitable vessel a convenient method being to dissolve in
200 parts of water so much of the soda bicarbonate as that quantity of water will
take up mixing the residue with the sulphide in powder in a suitable vessel of
capacity about equal to contain the mixture and the solution (in 200 parts water)
agitating and heating the whole gradually to boiling until the whole of the sulphur
(or such a percentage thereof as may be economically obtained by the treatment)
be eliminated as bydrogen sulphide. The quantity of water (200 parts) is about
sufficient (at 100° F) to dissolve the whole of the soda when reduced to mono-
Carbonate which results from the treatment, when the reactions are complete the

page_text: solution cleared by settling may be drawn off and the residuum washed in the
usual manner and similarly the liquors may be evaporated and crystallized or
otherwise disposed of.
In the case of alkali "waste" which is a crude sort of sulphide a portion of.
unlixiviated "black ball" may be added to it, the contained alkali. thereby
furnishing the intermedium it may be only partially lixiviated or the calcium
sulphide ("waste") in the black ash may be subjected to the reactions herein
mentioned before or at any stage of the usual lixiviation.
It will be observed that in the foregoing the gulphur is mentioned as being
separated from the "sulphide" in combination with hydrogen, that is, as hydrogen
sulphide and the base (calcium) or otherwise) converted into a ourbonate which
with any foreign matter constitutes the insoluble residuaus; the intermediam (soda
or otherwise) being soluble can be separated by solution and used again or otherwise
disposed of and the carbonated base may be burned into line or otherwise utilized ;
if to be burned into lime it should be previously mixed with a little clay just
sufficient, with water, to give it coherence in the form of blocks for the kiln. The
hydrogen sulphide may be burned for the vitriol chamber or reduced to free sulphur
by the well known reaction of sulphurous acid or be otherwise utilized in any
known manner.
I now proceed to give a general explanation of the manner of conducting the
processes and a description of the kind of apparatus to be employed, either of
which may be variously modified as I do not restrict myself to the precise details
mentioned.
The vessels to be employed may be conveniently designated "tanks" but may
be of any suitable form dimensions and material and be fitted with closely fitting
covers (a man-hole and cover will answer) pipes, taps, and connections as will be
understood to bo requisite and of obvious use, the arrangement being very much
after the manner of the well known "Woulfe's" apparatus and some of them (to
be specified) preferably fitted with an agitator or stirrer of any suitable kind and
provided with a source of heat (steam pipes or otherwise) each inlet pipe (for the
gases) to be of such form and position as to have its delivery end below the surface
of the fluid in the tank (2 or 8 feet) each foot of depth requiring rather less than
half a pound per inch pressure force applied to the gas to be obtained from a
"blower" (or fan or otherwise), if the gas be driven into the tanks with con-
siderable force the commotion caused thereby will supply the use of and dispense
with mechanical stirrer, but generally the latter will be the more advantageous of
the two.
The pipe to convey the gas out of the tank (the gas exit pipe) to have its
opening (to receive the gus) in the upper part of the tank, above the contained
fluid the arrangement being generally characterised as being of pipes with one leg
longer than the other and it is obvious that the exit pipe of the first tank will be
the inlet pipe of the second tank and so on in the order of the direction of the
course of the gus through them, that is, if there be a series of tanks which is
preferable (2 or 3 or more) rather than one tank of larger size. In addition to the
tanks mentioned and which may be named "desulphuring" tanks there are to be
provided subsidiary vessels. The gas liberated in the vessels (hydrogen sulphide)
is to be directed in its course from the several vessels to the utilizing receptacle
and as much as possible the access of air to the sulphides to be prevented.
If the carbon dioxide gas be pure, the "blower" receives it from its source and
forces it into the first of a series "desulphuring tank" each of which has been
obarged thus, partly with sulphide in powder and then quite filled up with solution
of super-carbonated alkali (the more it is carbonated the more accelerative to the
reaction) from a contiguous store tank and the cover made tight the connecting
tube with the "store tank" (which should be about the same level) being left open
and the gas exit tube closed the first effect of the gas pressure should be used to
force a little of the solution hack into the store tank so as to have a stratum. of gas
at the upper part of the desulphuring tank, the connection with the store tank

page_text: being then closed the gas exit pipe opened and the agitater put into motion the
process goes on and the quicker if the tanks are moderately heated such as by any
available waste heat most of the carbon dioxide is absorbed liberating hydrogen
sulphide which with the unabsorbed carbon dioxide passes out at the exit pipe
into the second desulphuring tank in which more of the carbon dioxide is absorbed
and more bydrogen sulphide liberated which passes into the next tank and so forth
through the series of tanks until the carbon dioxide being completely absorbed
hydrogen sulphide only passes out at the exit pipe of the last tank of the series to
the utilizing receptacle whether it is to be burned for vitriol or otherwise when
the contents of either of the desulphuring tanks (say the first of the series) have
completed the reaction. All the sulphur by the process being eliminated or
practically so much of it as may be economically, suitable arrangements are made
for emptying and recharging it. Altering the connections of the pipes, thus the
gas inlet pipe and the gas exit pipe are closed and the current of the gas conducted
to the second tank direct, by a pipe provided and adjusted for that purpose, the
contents of the first tank are then run out by a pipe provided for the purpose into
a contiguous "settling tank which is then closed tight and the desulphuring
tank again charged as before and the previous pipe arrangements resumed. After
the settling tank contents have subsided the clear liquor may be drawn off and
the sediment be washed in the usual manner all the liquors being run into a
reservoir of some kind for concentration by evaporation to be used again or
otherwise, the insoluble residuum in the settling tank (which it is better to work
moderately heated) to be dried off and removed for use. As all the liquors usually
retain a little hydrogen sulphide (less if hot) they may be cleared by a little
litharge or other known manner or the vapours of evaporation and such like may
be conducted by a flue or pipe to some adjacent furnace. In washing the sediment
in the settling tanks in practice it will be well to use the water for the first
washing previously to wash out the desulphuring tank. as the whole contents will
not at once be run out clear.
دو
In the case of Alkali waste it may be convenient to arrange the desulphuring
tanks for the double service of lixiviating and afterwards heating the insoluble
residuum (sulphide) or the lixiviation may be made in the usual manner in tanks
contiguous to the desulphuring tanks and the residuum afterwards transferred.
If the carbon dioxide gas be obtained from fuel as previously alluded to, burned
with excess of air the oxygen present should be reduced to a minimum. And it
may be well to wash the gases in the usual manner by first passing them through
water, the
guses then
may be considered to be nitrogen, carbon dioxide, and
oxygen which latter renders a modification of the foregoing process desirable in order
to avoid the oxidation of the sulphide namely I provide a tank, (or a series) into
which the gases are passed previous to the "desulphuring tanks" and the arrange-
ment of the tank may be in the following manner, the tank longer than wide with
a tight fitting cover provided with a transverse diaphragm or partition projecting
about half way down the tank joined to the top and sides, air tight the tank to do
a double service preferably to two tanks, the tank to be supplied with as much
iron oxides as its capacity and the operation will conveniently admit of and then
dilute acetic acid or other weak acid poured in to nearly filling it, the structure of
the tank includes a man hole or otherwise for filling and an exit for occasionally
running out the contents, with pipes (similar to the desulphuring tanks) for
passing in the gases and their passage out and also some contrivance for continually
(when working) transferring the contents from each division to the other for this
purpose two helical revolvers or screws may be arranged longitudinally the whole
length of the tank or thereabouts in the lower part of the tank passing beneath
the diaphragm from the cover, so that one screw continuously moves the contents
of the tank from left to right the other from right to left the operation then will
be the gases being forced into one division of the tank (below the fluid) by a pipe,
the diaphragm (if sufficiently deep) and the fluid prevents them from passing to
the other division, the iron absorbs oxygen. And the residual gases pass out at

page_text: the top of the tank division and then into the desulphuring tanks through which
they pass from the last of the desulphuring tanks by a return pipe to the other
division of the tanks (with iron contents) which they enter (below the fluid) and
similarly the diaphragm and the fluid prevent their passage to the other division,
the gases returned from the desulphuring tanks, have become hydrogen sulphide
and nitrogen and being passed into the second division of the (iron oxides) tank
the sulphur of the hydrogen sulphide is retained the nitrogen passing out at an
exit pipe to the atmosphere or may be utilized The intention of the fluid is to
form with the diaphragm an air tight trap to the gases and the acid slightly
tending to solve the iron and prevent the formation of lumps.
Manganese or other metal may be used with or in lieu of iron. The tank should
be occasionally cleared of the sulphur by a pipe or other suitable means.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Francis Bristow Rawes in the Great Seal Patent Office on the
22nd September 1882.
"IMPROVEMENTS
EBANOIS BRISTOW RAWES of Stratford in the County of Essex
SOME OF ITS COMPOUNDS A
IN AND IN APPARATUS FOR OBTAINING BULPHUR AND
AND IN THE TREATMENT THEREOF AND ALSO OF THE ASSOCIATED PRODUCTS
"2
This Invention refers to a new process and apparatus for treating
sulphates for obtaining sulphur in the condition of hydrogen sulphide; als
new process or processes and new apparatus for treating compounds namely
sulphides and to now apparatus for treating another compound obtained therefor
viz hydrogen sulphide, also and to new apparatus for treating associated products
namely an intermedium liquid and an alkaline solution which results in certain
cases and also carbonate of lime sediment.
There are several compounds, both natural and artificial, of sulphur with bases,
to which the processes hereinafter described or some of them are applicable as will
be well understood by chemists, particular reference being made to the more
"alkali
abundant compounds of sulphur with lime (calcium) as a base such as
waste and lime sulphates.
وو
If the sulphur compound be a sulphate (gypsum for instance) which however is
rarely pure more or less of other matter being present, or in any state of com-
bination with sulphur other than that of sulphide and which nevertheless is capable
of be.Eg reduced to the state of sulphide (old "alkali waste" is an example as the
sulphur present in it is generally found to be in a variable state of oxidation some
parts or parcels being oxidated to higher degree than others) I first reduce the
sulphur compound to that state (of sulphide) by any known process for instance;
in the case of gypsum, pulverizing and intimately mixing it with carbon (bituminous
coal for instance in the proportions of 30 parts Bituminous coal or a little in excess
thereof which may be desirable (although in some cases the presence of other
matter such as carbonate of lime may be sufficient in quantity to diminish the
proportion of coal as mentioned which however any chemist will understand,
to regulate) and it may be remarked that the proportion of reducing agent t
mentioned, is what I consider to be preferable from the tendency of carbon
the conditions of the reducing process to combine to form carbon monokide
rather than carbon dioxide) to every 100 parts of gypsum and then strongly
heating the mixture avoiding the contact of air in a crucible, or a retort or other
suitable apparatus for 2 or 3 hours or longer if the quantity operated upon being
large requires it in order that the heat may permeate the whole mass or the gypsum
or other sulphur compound may be reduced to the state of sulphide in any other
known manner.
If the compound to be operated upon contains any material other than sulphur
and its combined base or bases (calcium or otherwise) such as any accidental or
occasional admixture or such as is ordinarily incidental to natural minerals which
it is desirable to separate because of its value or because of its detrimental
presence I obtain by any known process a solution from the crude compound
(sulphide and admixture) in any suitable menstruum (hydrochloric acid for instance)
and according to what may happen to be present in the compound I in any known
manner obtain and utilize any bye products that may be of value or suitable and
recover the base (lime or otherwise) as "sulphate" by the well known reaction of
treatment with sulphuric acid and heat collecting in the usual manner
utilizing the hydrochloric acid driven off. The sulp ate may then be treated a
and

page_text: specified in the preceding paragraph. Calcium chloride a bye product in many
chemical operations may be similarly converted (by sulphuric acid) into sulphate of
lime and then be subjected to treatment as other sulphates as mentioned above
for reduction to sulphides.
To displace the sulphur from combination with its base calcium or otherwise) I
employ carbon dioxide (carbonic acid) conjointly with intermedium (such as will
be mentioned further on) as a contact agent and apply agitation to bring successive
particles of the sulphide (in a suitable vessel the sulphide preferably being in a
pulverous condition or capable of becoming disintegrated in the process) within the
influence of the reactions of the carbons dioxide and the intermedium which
(intermedium) should fill the vessel to the exclusion of atmospheric air.
That carbon dioxide reacts upon sulphides eliminating hydrogen sulphide is
known but the use of an intermedium and the employment of agitation (which
may be caused by the carbon dioxide gas being driven in with sufficient
disturb the sulphide and to maintain it in a state of commotion in the
dium fluid but preferably by a mechanical stirrer any such as will prevent
turb the aggregation of the particles and cause a constant change of their
place keeping them disturbed about the containing vessel or suspended in the fluid
in such a manner as will mechanically favor the action of affinities and the re-action
of carbon dioxide) are important aids to the operation of the affinities by bringing
the comparatively dense sulphide molecule by molecule as it were into contact with
the carbon dioxide gas to liberate the sulphur (from its base) which entering into
combination with hydrogen forms the well known chemical compound "hydrogen
sulphide"; I also to assist the process prefer to heat the containing vessel any
available heat being used as a temperature of about 100 F. appears to be sufficient
but may be higher.
The operation of carbon dioxide gas upon a mass or bulk of a sulphide (either
dry or moist) is found to be in the processes heretofore tried only partial and very
imperfect and also the presence of atmospheric air (from its oxidating effect) is
most objectionable and therefore the exclusion of atmospheric air and the use of an
intermedium and the employment of agitation are distinguishing features in my
process for treating sulphides with carbon dioxide and each of them is respectively
contributive, but the conjoint use and employment of all in the aforesaid treatment
is the more complete process.
For the intermedium 1 preferably use an alkali (as for instance soda for soda
waste potash for potash waste) carbonated or supercarbonated and in solution to
In le atmospheric air from contact with the sulphide during the process, as it is
pt to obviate the ready tendency of sulphides to oxidation. The solution
saturated solution or thereabouts of supercarbonate and it is better if
✓ater for the solution has been previously boiled so as to eliminate the air to
he intent that oxidation of the sulphur should be as much as possible avoided.
The carbon dioxide (CO) may be obtained from any source and particularly from
lime kilns or from the combustion of fuel or from both, a sufficient access of air
aving been provided to prevent the presence of carbon monoxide (CO) instead of
arbon dioxide the remaining or uncombined oxygen being as far as is practicable
fterwarde absorbed or otherwise got rid of or reduced to a minimum in any suitable
manner; such a mixture of gases passed through protoxide of iron yields some of
its oxygen to the iron, it becoming sesquioxide which may be again reduced to
protoxide by hydrogen sulphide according to reactions practised at gas works, or
the carbon dioxide may be separated from such mixed gases and be afterwards
utilized in the manner and apparatus hereinafter described and it will be well by
a little attention to the admission of air to the fuel and management by control of
a damper or the like to regulate the supply of air to the fires so that no more
excess of oxygen be supplied (in the air) than is requisite for perfect and complete
combustion of the fuel so that afterwards it may be the more easily reduced to a
minimum. The heat of combustion of the gases may be utilized while cooling
them down to about the temperature of the atmosphere. I do not however claim

page_text: such reduction of the amount of ozzygen as part of my invention as it may he dispensed
with if the expense is found to be too great to make it commercially profitable to employ it
As an abundance of carbon dioxide can be obtained at a cheap rate it may be
convenient in some cases to have a prepared supply of alkali empercarbonated so as
to use the requisite quantity of carbon dioxide in a state of combination (with the
alkaline intermedium) applied to the sulphide with agitation in a closed vessel and
sufficient water to exclude the air in order to prevent oxidation the process being
assisted by heat. For instance instead of presenting the carbon dioxide in the
state of gus s to the sulphide and the intermediam, for the ro actions, it may be used
in combination with the alkaline intermedium, thus to overy 72 parts of calcium
sulphide (or for other sulphide in the quantity proportionate to its chemical
equivalent) take 168 parts of bicarbonate of soda (if soda be the intermedium
alkali used, any other alkali in quantity proportionately to its chemical equivalent)
with agitation in a suitable vessel arranged so that it may be heated, a convenient
method being to dissolve in 200 parts of water so much of the sodu bicarbonate
(the before mentioned 168 parts) as that quantity of water will take up mixing
the residue of the soda bicarbonate (the mentioned 108 parts) with the sulphide in
powder in a suitable vessel of a capacity about equal to contain the mixture and
the solution (in 200 parts water) agitating and heating the whole (gradually to
obviate the decomposition of the bicarbonate and dispersion of the carbon dioxide
before it has had time to react upon the sulphide) until it boils and containing
until the whole of the sulphur (or such a percentage thereof as may be economically
obtained by the treatment) be eliminated as hydrogen sulphide which is to be
collected for use the same as that obtained in any other manner. The quantity of
water (200 parts) is-about-sufficient (at 100°-F.) to dissolve the whole of the sode
(when reduced to monocarbonate which results from the treatment, when the
re actions are complete) and the solution, cleared by settling, may be drawn off and
the residuum washed in the usual manner and similarly in the usual manner the
solution and washings may be evaporated concentrated and crystallized or otherwise
disposed of
In the case of "alkali waste" which is a crude sort of sulphide a portion of
unlixiviated "black ball" may be added to it, the contained alkali of which (with
water) will dissolve out and obviate the addition of other intermedium, or the
"black ball "
may be only partially lixiviated, or the calcium sulphide (waste) in
"black ball" may be subjected to the re-actions hereinmentioned (in suitable
vessels) during any stage of the usual process of lixiviation.
It will be observed that in the foregoing the sulphur is mentioned as being
separated from the sulphide. in combination with hydrogen that is as hydrogen
sulphide, a well known mechanical chemical compound and the base (calcium or other-
wise) converted into a carbonate which with any foreign matter (if any) constitutes
the insoluble residuum; the intermedium (soda or otherwise) being soluble can be
separated by solution and used again or otherwise disposed of and the carbonated
base may be burned into lime or otherwise utilized if to be burned into lime it
should be previously mixed with a littly little clay just sufficient with water to give it
coherence in the form of blocks and then dried for the kiln. If the sulphide to be
desulphured be "alkali waste "with an admixture of "hlack ball" or if it be
"black ball" wholly which has not been lixiviated in the usual manner then the
resulting products that is to say the solution and the lime carbonate sediment will
generally have associated with them compounds such as in the usual treatment
would have passed out with the lixivium of the "black ball" & such lixivium
usually contains (besides other saline compounds) much caustic alkali which
becomes carbonated in the desulphuring tank, I in such case use the solution if
desired as an intermedium but only so often or until the accumulation of saline
compounds has become objectionable. I then add the washings of the sediment
evaporate to dryness dissolve and cystallize in the usual manner.
The washed lime carbonate sediment from the said "black ball" treatment I
prefer to treat with alkaline hydrate in the tank S** or other suitable vessel to

page_text: dissolve up alumina hydrate (if any) that may have become insoluble by the
carbonating process and may have deposited and the solutions may be concentrated
in the usual manner and disposed of as aluminate of soda for instance or otherwise.
The hydrogen sulphide may be burned or heated in contact with atmospheric air
or oxygen, the resulting sulphurous acid may be utilized in the vitriol chamber or
for other purposes or the hydrogen sulphide may be converted or reduced to free
sulphur by the well known method or re-action of sesquioxide of iron similar to
the practice at gas works or by the reaction (as known) of sulphurous acid or be
otherwise treated or utilized in any known manner.
I now proceed to give a general explanation of the manner of conducting the
processes and a description of the kind of apparatus to be employed either of
which may be variously modified as I do not restrict myself to the precise details
mentioned.
The vessels to be employed may be conveniently designated "tanks" but may
be of any suitable form dimensions and material and be fitted with closely fitting
covers (a manhole and cover will answer) pipes taps and connections as will be
understood to be requisite and of obvious use, the arrangement being very much
after the manner of the well known "Woulfes" apparatus and some of them (to be
specified) preferably fitted with an agitator or stirrer of any suitable kind and by
preference provided with a source of heat (steam pipes or otherwise) each inlet
pipe (for the gases) to be of such form and position as to have its delivery ends
below the surface of the fluid in the tank (3 or 4 feet or more) each foot of depth
requiring rather less than half a pound per inch pressure force applied to the gas
which pressure may be obtained from a "blower" (or fan or otherwise). If the
gus be driven into the tanks with considerable force the commotion caused thereby
may supply the use of and dispense with mechanical stirrer but generally the
latter will be the more advantageous of the two. Each pipe for the conveyance
of gps out from the vessels or tanks (the gas exit pipes) to have its opening (to
receive the gas) in the upper part of the tank above the contained fluid, the
arrangement being generally characterised as being of pipes with one leg longer
than the other (or syphon pipes) the longer leg descending beneath the surface of
the fluid for the delivery of the gas into the fluid in the manner well understood
and it is obvious that the exit pipe of the first tank (of a series) will (in its longar
leg) be the inlet pipe ie. the delivery pipe of the gus to the second tank (of a
series) and so on in the order of the direction of the course of the gas through
them, that is, if there be a series of tanks which is preferable (2 or more). rather
than one tank of larger size. In addition to the tanks mentioned and which may
be named "desulphuring tanks" there are to be provided subsidiary vessels for
uses hereinafter described. The gas liberated in the vessels (hydrogen sulphide) is
to be directed in its course from the several vessels to the utilizing receptacle and
as much as possible the access of air to the sulphides and the escape of the hydrogen
sulphide into the atmosphere to be prevented.
If the carbon dioxide gas be pure the "blower".receives it from its source and
forces it into the first desulphuring "tank," if a Beries, each of which has been
charged thus, partly with sulphide in powder or condition to disintegrate and then
quite filled up with solution of supercarbonated alkali (the more it is carbonated
the more accelerative to the re-nation), from a contiguous store tank or reservoir
and the cover made tight, the connecting tube with the store tank (which should
be about the summe level or a little higher) being loft open the top of the gus exit
tube closed and the top of the gas delivery tube open the first effect of the gas
pressure should be used to force a little of the solution hack into the store tank so
as to have a stratum of gas at the upper part of the desulphuring tank the con-
nection with the store tank or reservoir baing then closed the gus exit pipe opened
and the agitator put into motion the process goes on and the quicker if the tanks
are heated (moderately as no apparent advantage is to be derived from the
generation of a large quantity of steam) such as by any available waste heat, most
of the carbon dioxide is absorbed, liberating hydrogen sulphide which with the
B

page_text: unabsorbed if any carbon dioxide passes out at the exit pipe into the second (of a
series) desulphuring tank in which more of the carbon dioxide is absorbed and
more hydrogen sulphide eliminated which passes into the next tank and so forth
through the series of tanks until the carbon dioxide is absorbed (or nearly all
absorbed in fact 1 find that very little carbon dioxide escapes absorption in the
first tank and so two tanks will generally be sufficient and it may be economical
to allow a small percentage to escape and hydrogen sulphide only (or with a small
percentage of carbon dioxide) passes out at the exit pipe of the last tank of the
Beries to the utilizing receptacle whether it is to be burned for vitriol or otherwise.
When the contents of either of the desulphuring tanks (say the first of the series)
have completed the reaction all the sulphur, by the process being eliminated from
the calcium (lime) or practically so much of it as may be economically suitable to
recover, arrangements are made for emptying and recharging it, first altering the
connections of the pipes; thus the gas inlet pipe and the gas exit pipe are closed
and the current of the gas conducted direct to the second tank (of a series) by a
pipe or pipes provided and adjusted with taps and connections suitable for that
purpose then the contents of the first tank are run out by a pipe provided for the
purpose into a contiguous settling tank which pipe is then closed tight and the
desulphuring tank again charged as before and the previous pipe arrangements
resumed it may however be convenient in practice to alter the arrangement of the
opened and the closed taps so that alternately each tank (supposing there are two)
is made to be the first of the series in a manner easily understood. After the
settling tank" contents have subsided the clear liquor may be drawn off and the
sediment be washed in the usual or any suitable manner all the liquors being run
into a reservoir of some kind to be used again or for concentration by evaporation
or otherwise and the insoluble residuum in the settling tank (which it is better to
work moderately heated) removed and disposed of. As all the liquors usually
retain a little hydrogen sulphide (less if hot) they may be cleared by a little
litharge or in any other known manner or any exhalation of hydrogen sulphide
may be conducted into the general receptacle of that gas or the vapours of
evaporation and such like as hydrogen sulphide exhalation may be conducted by a
flue or pipe to some adjacent furnace. In washing the sediment in the settling
tanks, in practice it may be well to use the water for the first washing (if several
washings be preferred) previously to wash out the desulphuring tank as the whole
contents will not at once be run out clear.
66
In the case of alkali waste it may be convenient to arrange the desulphuring
tanks for the double service of lixiviating and afterwards treating the insoluble
residuum (sulphide) therein or the lixiviation may be made in the usual manner in
tanks contiguous to the desulphuring tanks and the residuum afterwards
transferred.
If the carbon dioxide gas be obtained from fuel as previously alluded to burned
with excess of air, the oxygen present should be reduced to a minimum and it may
be well to wash the gases in the usual manner by first passing them through water
The gases then may be considered to be a mixture of nitrogen carbon dioxide and
oxygen the presence of which latter gas requires particular attention so that the
quantity admitted to the sulphide may be reduced to a minimum (in order as
much as possible to avoid the oxidation of the sulphide) or be entirely got rid off
It is well known that chalk &c treated with acid yields an approximately pure
carbon dioxide but its expense is an objection to its use. I however obtain an
approximately pure carbon dioxide (by a process hereinafter described) which may
be used for eliminating the hydrogen sulphide without introducing to the sulphide
an appreciable quantity of oxygen. But advantage mar if desired be taken of the
tendency of some metallic oxides (iron for instance) to absorb and combine with
more oxygen when presented to them to diminish the presence of oxygen in ganes
of combustion to a minimum ; such oxides for instance protoxide of iron in the
presence of oxygen oxidises to cesquioxide which in the presence of hydrogen
sul, hide becomes again protoxide iron; reactions well understood and practised at

page_text: some gas works by alternately foreing in atmospheric air and the sulphuretted gases,
an application of which principle I employ as follows. I provide a tank or a series
of tanks, into and through which the flue gases are passed or forced previous to
their entering the desulphuring tanks and the arrangement of them may be in the
following manner; the tanks to be about square in transverse section and to be in
length about twice the width, to be provided with a tight fitting cover and at
about mid length a transverse partition or diaphragm projecting about half way
down the tank and be fixed airtight to the top and sides (that the tank may de
double service without removing the contents or chifting the connections) the
contents of each tank to be iron (a mixture of protoxide and sesquioxide will do)
and in quantity suitable to the capacity of the tank (about one sixth in bulk) and
nearly filled with water or weak ooid. The construction of each tank to include
manhole or otherwise for filling and pipes for gases and an exit pipe for emptying
as occasion may require and also some contrivance for continually (whilst the gases
are being passed through) transferring the contained iron oxides from either one
division to the other. I prefer two revolving screws arranged horizontally
longitudinally the entire length of the tank (or thereabouts) in the lower part
thereof and just passing free and beneath of the aforementioned diaphragm the
screws to be connected with gearing (outside the tank) by axles or spindles passing
through stuffing boxes and arranged to revolve in contrary directions the one
moving the contents (iron oxides) from left to right the other from right to left and
this will be assisted by a longitudinal vertical part division between the two screws
but to control the direction longitudinally rather than sideways The conduct of
the operation is as follows: the gases are forced into one division of the tank (one
of the divisions seperated by the diaphragm) by a pipe passing below the fluid and
delivering the gases near the bottom of the tank and any similar arrangement for
distributing the gas as that hereinafter-mentioned in respect of the desulphuring
eylinders may be adopted. The diaphragm (which must be sufficiently-deep)
together with the fluid in the tank "traps" the gases and prevents them from
passing to the other division of the tank the protoxide of iron absorbs oxygen and
becomes sesquioxide, the residual gases (which may be considered to be nitrogen
carbon dioxide and a diminished proportion of oxygen) pass out by a pipe at the
top of the tank (in the division of the tank whereat they entered) and then
similarly through a division of each tank (if a series) to the last tank whence the
gases pass into the desulphuring tank or tanko (if a series) through which they
pase in the usual manner entering by a pipe delivering the gas beneath the fluid
end the gas escaping by an exit pipe in the upper part. Thence (from the last of
the desulphuring tanke by a "return pipe" they re-enter the tank (or tanke if a
series) which has a diaphragm for forming two divisions therein and contains iron
oxides as explained above The gases enter (below the fluid), and being similarly
as before trapped " by the diaphragm and the fluid their passage to the other
division of the tank is prevented, but they are allowed to pass out in the usual
manner from the upper part of the tank by an axit pipe. The gases returned from
the desulphuring tanko (to the tank or tanks having diaphragm divisions and
containing iron onides); and having therein parted with carbon dioxide (to the
sulphide) and become (by the substitution) chiefly hydrogen sulphide and nitrogen.
In order to separate the sulphur from the hydrogen by the forementioned fron
reactions the gases are passed into the second division of the tank (containing iron
omides) that is to say into the division of the tank that was avoided by the gases
when in the first instance they were passed through the tank (or tanks) and in
practice it will be well to regulate the admission of the games forced through the
apparatus by the use of a top or valve or by adjusting the motion of the blower to
the absorbing or decomposing rate or capacity of the iron oxides (provided for the
purpose of effecting the well known decomposition or reactions) so that no
hydrogen sulphide be allowed to escape at the exit pipe to the atmosphere as the
presence of hydrogen sulphide can be easily detected chemically for instance, paper
moistened with lead acetate becomes dark coloured. The rate of the reaction of the

page_text: sesquioxide of iron upon bydrogen sulphide has generally been found to diminish
as free-sulphur accumulates.
The sulphur of the hydrogen sulphide is thus as free sulphur all or nearly-all
retained, the residual gases chiefly nitrogen passing out at on oxit pipe to the
atmosphere or may be utilized if any suitable manner presents itself. The office
or use of the fluid in the tanks is with the diaphragm to form a gastight trap to
the gases, so that in passing through a series of tanks the operation of the oxygen
of the admixed atmospheric air may be limited as much as possible to the half of
the tank which they are-directed through, in order that the iron protexide should
freely absorb oxygen and become sesquioxide in the one division, and then by a
sufficient motion of the "serowe" or "other stirring action, the sesquioxide, being
transferred to the other division may be acted upon by the hydrogen sulphide and
redneed to protonide again. Manganese or other suitable metal may be used with
or in lieu of iron. The contents of each tank will require to be occasionally run
out at a piro or otherwise to separate the free sulphur from the iron oxides which
may be done by solution of the sulphur in bisulphide of carbon (as is a well known
method)-recovering the sulphur and the bisulphide of carbon separate, by distillation
or separate the sulphur from the iron oxides by sublimation or other convenient
method.
The method for obtaining for use approximately pure carbon dioxide as referred
to above from gases of combustion or lime kilns is as follows:-1 pass the gases
through a suitable vessel (or a series) in which there is an absorbent of carbon
dioxide such as a strong or saturated cold solution of mono-carbonate of soda or
potash or a mixture, the vessels being kept cool by running water round them or
otherwise during the passage of the flue gases, the carbon dioxide is absorbed and
the super-carbonated soda or other alkali being less soluble deposits, the oxygen
nitrogen, &c. escaping by an exit pipe the fluid may when the process is completed
be drawn off (to be used to dissolve more soda or otherwise) and about half of the
carbon dioxide gas driven off by heat or this may be varied by the accumulation
of supercarbonate from several successively treated solutions (of mono carbonate
with carbon dioxide) before it is heated for driving off free carbon dioxide, or the
carbon dioxide may be driven off by heat without drawing off the solution from
the vessel a process that requires no particular directions to a chemist.
In the accompanying drawing some parts are shown single and some parts are
shown in pairs and in the explanation thereof the description corresponds but they
are not thereby necessarily limited thereto as it will readily occur to the
manufacturer that some of the parts may be varied in number or otherwise
modified in details dimensions proportions or in any other manner that circum-
stances may require or suggest and any suitable materials may be employed it
being simply my aim to plainly indicate that which according to the best of my
judgment I consider to be the best manner or method of carrying into effect the
aforementioned process or processes more particularly and fully that which I
consider to be a main feature or central element of the same namely the
dissociation of sulphur from its base as hydrogen sulphide by the treatment with
carbon dioxide And similarly to eliminate complexity as much as possible 1 omit
from the drawing such parts as gearing and other parts the use and arrangement
of which can be obviously apprebended and the form position, and relations of
which can be readily supplied by ordinary engineering experience and may be
adapted to suit any existing plant.
Regarding the most economical source of carbon dioxide (CO2) to be flue gases
or lime kiln vapours their heat may be utilized to eliminate carbon dioxide (derived
from a previous operation) in the manner about to be described i.e. I first use any
available heat of such gases and then when sufficiently cooled (in any manner)
I obtain from them as supply of carbon dioxide. The gases from the flues or such
like (which may be regarded as a mixture of carbon dioxide nitrogen and air) pass
into a purifying tank or apparatus illustrated at Figures 1. 2. 3 and 34, figure 1
being a vertical cross section half on line 2 x and half on line y y and figures 2

page_text: with
an
and 3 longitudinal vertical section of the carbon dioxide purifying tank, the one
showing the horizontal flue pipes in full lines with the vertical pipes dotted, the
other showing the vertical in fall lines with the horizontal dotted and Figure 84
being a horizontal section at a b (the horizontal flue pipes being arranged somewhat
after the manner of a locomotive boiler) The gases pass by the pipe A into the
being a close
space B beneath D (which forms the bottom of the tank proper
vessel with the exception of the pipe openings and is provided with tapped
apertures for pouring in and for drawing off fluid) and in the direction of the
arrows the gases follow along E F G and out at H whence the flue gases may be
conducted through a second of a series of such vessels to warm the tank and
contents and to further lower the temperature of the gases; and the gases may be
used alternately with a series of carbon dioxide purifying tanks the partially cooled
gases being used to warm a tank to be followed by fresh hot flue gases to heat it
to the requisite temperature or the gases may in succession be passed through
more than two tanks after which they may be further cooled in any manner such
as by passing them through a pipe (or worm) in water to the temperatue of the
air, or cooler being desirable, and then (when sufficiently cooled) the gases may be
oonducted through the several divisions in one of the tanks shown by the vertical
lines (Figure 3) entering the tank at J and out of the first division by the bent
pipe at K and into the second division and so forth in succession through each
division and the gas delivery pipes may have the same arrangement for
distributing it as is mentioned hereafter in relation to the desulphuring
cylinders (which may be of any convenient number) to the exit at M (or
in a similar manner through several such tanks). In connection
blower may
to act in part as
pipe J
be conveniently placed
exhaust from the horizontal flues E F G and to force the gases through the tank
as described. The gases at J being carbon dioxide nitrogen and air the tank is to
be nearly filled with a strong or saturated solution of soda monocarbonate (or
other absorbent of carbon dioxide or potash or a mixture nor need they be
chemically pure) which by absorbing the carbon dioxide becomes a less soluble
super-carbonate and subsides from solution, little less than the nitrogen and the
air escaping at pipe M into the atmosphere. During the time the carbon dioxide
is being absorbed it is desirable to keep the temperature of the tank low, which
may be done in various ways and it may be convenient for that purpose to connect
the flue pipes E F and G by suitable taps and pipes with a source of cold water
to be run through them. When all or nearly all the soda in the tank has become
supercarbonate the solution may be run out and may be again used to dissolve
soda monocarbonate (which may be the monocarbonate reduced by a previous
treatment of supercarbonate or otherwise) to be similarly supercarbonated and the
residuum in the tank of subsided supercarbonate have about half its carbon
dioxide driven off by heat (the temperature of boiling water to about 300° F.
I consider to be suitable but generally the extraction of carbon dioxide is
accelerated by increase of temperature) from any source or preferably in the manner
specified above by the flue gases being passed through the tubes E F G the soda
supercarbonate being reduced to monocarbonate thus the monocarbonate is super
carbonated by passing the cooled flue gases through tank by pipas J to M then
the carbon dioxide is driven off by the heat of the hot gases or flame being passed
through pipes E to H then the solution from a previous operation may be run
into the tank to dissolve up the soda reduced to monocarbonate and so on round.
It may however be a desirable modification in some cases to obtain an accumulation
of supercarbonate in a tank by treating, with carbon dioxide in the manner
described, several successive solutions of monocarbonate and then (when sufficient
is obtained) as precipitated or subsided supercarbonate) driving off the carbon
dioxide as described.
Figure 4 is a plan and Figure 5 a side elevation and part section through the
centre excepting that for plaiuness the pipe B1 is shown as though it was in the
same straight line instead of being at an angle, and R' is wide of the central line

page_text: of parts generally corresponding. When the carbon dioxide is to be driven off as
described from tank (Figures 2 and 3) the pipe M is connected with pipe N
(Figures 4 and 5) at which point a blower may be conveniently adjusted and the
carbon dioxide forced in the course indicated by the arrows along pipe O whence
it descends by the two vertical pipes P P placed in the margin of the desulphuring
cylinder Q¹ and passing to nearly the bottom of the cylinder. Figure 6 is a part
section on a larger scale showing the relations of the pipes 00 with the bottom
portion of the cylinder where the carbon dioxide passes into the cylinder at which
place the smaller ring of the cylinder passes a little distance within the larger and
bottom ring of the cylinder (at a Figure 6) so as to form a vertical rim projecting
downwards all round the cylinder providing a kind of reservoir for the carbon
dioxide so that it may enter the body of the cylinder at any part of its circum-
ference. The carbon dioxide may however be conducted into the cylinder at any
other part and any other method favourable to its distribution may he adopted in
connection with the construction of the gas delivery tubes. The tanks Q¹ and Q*
being charged with sulphide (as hereinafter described) carbon dioxide is absorbed
and hydogen sulphide eliminated which with any unabsorbed carbon dioxide
passes to the upper part of the tank and out by the pipe S Figures 4 and 5 into
pipe V (Figure 4) thence by pipe W to pipe X whence it descends by two pipes
(similar to pipes P P in Q¹) into Q where any carbon dioxide present will be
further absorbed and hydrogen sulphide liberated the course of the gases will
thence he (similarly to Q¹) by an ascending pipe to Z whence the course is by B
and B to Y where it is directed downwards into a tank or vessel d which is
similar to Figure 3 but without the horizontal flue pipes and is fitted with one or
more vertical divisions and syphon pipe or pipes to contain an absorbent of
carbon dioxide (soda monocarbonate solution for instance) adapted to retain all
or nearly all of any carbon dioxide that may be remaining mixed with the gas or
gases passed through it; thence the approximately pure hydrogen sulphide issues
from e and may be conducted into any suitable receptacle to be reduced to free
sulphur by any known manner or process or as herein described or otherwise
utilized or disposed of.
The taps, pipes and connections are so arranged that the current of the gases can
be directed in such a manner that each tank may alternately have the priority the
taps turned on and the taps turned off regulating the course as may be observed
by an examination of the drawing (Figure 4) and also whilst either of the tanks
is being recharged with sulphide it can be shut off or isolated from the current of
the gases. When a tank (say Q) is to be charged with sulphide the taps b, c, d, e, f, g
Figure 4 and Figure 5 are closed (such other taps being opened as will direct the
course of the gases from N (Figure 4) to tank Q, and through B and B¹ to Y and
out at e) a conveniently working quantity of sulphide is then put in at the
manholes j, Figure 4 upon the false bottom o Figure 5 which is preferably but not
necessarily curvilinear, the manholes ; are then to be closed tight and the taps g
and Figure 4 and Figure 5 opened so that the intermedium may flow from
the reservoir R¹ to fill up the tank expelling the air at tap p Figure 5 (or a pipe
having a tap may connect the top of the cylinder with the top of the reservoir)
the pipe p is also to shew when the cylinder is full by fluid instead of air escaping
thereout when it is to be immediately turned off, the gas from N Figure 4 is then
turned into the cylinder by tap (tap being turned off) until the gas pressure
forces a portion of the intermedium back into the reservoir R¹ and the surface in
the cylinder depressed about two inches to be ascertained by a gauge in the
cylinder similar to that used for steam boilers (not shown in the drawing); the
tap g is then turned off and the other taps turned so as to direct the gas through
first one tank then through the other and so forth out by the usual course, the
agitator is then put in motion and rotated until the sulphide is desulphured to
the extent required, which a little experience will generally inform of the requisite
time but a sample may be drawn at tap m Figure 4 (provided for that purpose)
and tested chemically.

page_text: When the contents of a tank is considered to be sufficiently desulphured (say Q¹)
the gus is turned off by taps e Figure 4 and Figure 5 (the course of the gas being
rectified by the other taps) and tap p Figure 5 opened, the contents are well stirred
up (by a rapid motion of the agitator) and then run by tap f Figure 4 into the
settler Sx and the tap f closed the other taps being adjusted, the tank Q can be
recharged. When the contents of settler Sx have subsided, the clear liquor is to
be pumped up into reservoir R¹ and then water (better if warm) run into the
settler and the whole well agitated by a stirrer (provided for that purpose) run
out at pipe n Figure 5 into settler Sxx and allowed to subside. The clear liquor
being drawn off may be used as a washing, several times and then added to one
of the Reservoirs R¹ to compensate for waste by evaporation &c. and the sediment
shovelled out into barrows to be dried or otherwise disposed of, or the bottom of
the settler Sxx may be provided with openings having close fitting sliding covers
which by being drawn aside will allow the sediment to fall into barrows or trucks
for removal. The sediment may however be dried in the settler if preferred.
When 'black ball" sulphide is treated as above described the manner of settling
and washing is modified as mentioned above.
Taps and u are provided that any exhalation of hydrogen sulphide from the
settlers may be admitted to the general channel of the gas and test taps for
obtaining samples of the passing gases may be placed at any requisite place.
o, Figure 5 is a false bottom, or grating, or perforated division (about midway I
prefer) on to which the sulphide is charged, the opening of the perforations or
distance between the gratings may be about half an inch. Down the centre passes
through a stuffing box the shaft or axle of the agitator carrying from its upper
part, projecting arms, from which swing suspended and moving freely (hinge-like)
distributors A which in revolving gradually abrade (chiefly by their weight) the
heaps of sulphide and distribute it about the tank, the smaller particles passing
from time to time beneath, the dimensions and form of the distributors being
regulated to allow them to pass freely within the tanks when swinging horizon-
tally. At the bottom are stirrers A' firmly attached to the shaft or axle, these
are of two forms the one moulded something after the fashion of a screw propeller,
by its revolution as a sort of scraper, stirs up the subsiding sulphide, tending by
its scythe-like form (in plan) to gather the sulphide about its middle (where it has
less altitude and in passing deposits it thereabouts, some counteracting effect to
the tangential force of revolution being thereby obtained) the form of the other
stirrers may be described as being a strong frame carrying "louvre boards
(preferably metal) at an angle of about 60°, the tangential force of revolution being
to the circumference, the deflecting operation of the "louvre boards" is towards
the centre. Figure 7 is a horizontal section or plan of the two forms of stirrer
arms and Figure 8, shows vertical sections of the scraping stirrer as made at either
end and at midway.
"
I prefer to arrange all the pipes (so far as is possible or desirable) with movable
covers to openings provided at those parts of the pipes where their direction is changed
(angles &c) so that examination may be had and any obstruction easily removed.
Figure 6 is a plan view and figure 10 a part section on line Y, Z, and part side
elevation of an apparatus for peroxidizing protoxide of iron and for reducing or
decomposing hydrogen sulphide to free sulphur. Figure 11 is vertical transverse
section of one of the tanke, and, Figure 12 plan section, also for peroxidizing the
protoxide of iron. TT-T &e are tanks each having a vertical diaphragm a in the
upper part and pipes for inlet and outlet of the gases. The inlet pipe reaches nearly
as low as the diaphragm, U. U are serowe provided in the bottom of each tank and
receiving revolving motion for the purpose of effecting a constant change e
tente from either one part of the tank to the other as stated above. V is a partition
between the screws for preventing them interfering with the action of each other.
of the con
The construction uses and arrangement of the other parts of the apparatus so far as
shown are similar to that described with reference to figures 1 to 8 with exception of
the "return" pipe shown at E, and the parts not shown must obviously be supplied.

page_text: The pipe A receives the flue gases and conducts them into one division of the
tanks TT &e which tanks are charged with iron oxide and water or weak noid
the gases descend by the syphon leg inlet pipe A' passing out by the outlet ripe A
then descending by the syphon leg end of the latter and so on through the whole
series; passing out by the pipe C which conducts it to the desulphuring urstem of
pipes and tanks Q'Q' from which the gases by the return pipe E pass to the tanke
TT &e and through the second divisions of same by ripes B and B passing
shecessively through the series.
The arrangement of the syphon inlet pipes A' and of the outlet pipes A' is
opposite, on the two opposite sides of the tanks T T &o the inlet pipes A being on
the left, on the upper or further side, and on the right, on the lower or nearer aide
as indicated by the lettering. The gases entering consist mainly of nitrogen,
carbonic acid and air; while traversing the series of first divisions they part with
oxygen thus converting the iron protoxide into sesquioxide; they then during their
passage through the desulphuring tanks Q1 Q3 part with their carbonic acid
eliminating hydrogen sulphide which letter together with the other remaining
gases by the return pipe E pass into and traverse the second division of the tanks
TT &e by the pipes B'B'.
During this passage the hydrogen sulphide re acts on the sesquioxide of iron
liberating free sulphur and reducing the sesquioxide into protoxide. The screws
UU during the process are operating so as to transfer the protoxide which has been
produced in one division of a tank T into the other division of the tank to be there
peroxided by the atmospheric air passing through it and similarly the peroxide is
passed back into the other division to be there reduced to protoxide and free
sulphur by the hydrogen sulphide reaction
I claim-
First: The combined process for converting certain sulphates into hydrogen-
sulphide consisting in first reducing the sulphate into a sulphide such as stated by
heat and by contact with the reducing agent or mixture in a closed vessel pre-
cautions being taken for excluding the air and thereupon treating the sulphide so
obtained with carbon dioxide in a closed vessel containing an intermedium precautions
being taken for excluding the air and with agitation all substantially as set forth.
Second: The process for producing hydrogen sulphide from a sulphide such as
stated consisting in treating the latter with carbon dioxide in a closed vessel con-
taining an intermedium precautions being taken to exclude the air and with agitation
all substantially as set forth, also the alternate process in which the carbon dioxide
is combined beforehand with on alkaline intermedium
Third The construction and combination of parts forming the improved apparatus
for purifying crude carbonic acid gas and utilizing its heat or not all substantially
es described with reference to Figures 1, 2, 3 and 34,
Fourth-The construction and combination of parts forming the apparatus for
obtaining hydrogen sulphide from a sulphide all substantially as described with
reference to Figures 4 to 8.
Fifth The construction and combination of parts forming the apparatas for
treating hydrogen sulphide with iron oxides for obtaining free sulphur, substantially
as described with reference to Figures 9 to 12.
Sixth The use of the products and of the byo products obtained by the processes
or treatment substantially as herein set forth and described.
In Witness whereof I the said Francis Bristow Rawes have hereunto set my
hand and seal this Twenty second day of September in the year of our
Lord One thousand eight hundred and eighty two.

page_text: LETTERS PATENT to Francis Bristow Rawes of Stratford in the county of
Essex for an invention of "IMPROVEMENTS IN AND IN APPARATUS FOR
OBTAINING SULPHUR AND SOME OF ITS COMPOUNDS AND IN THE TREATMENT
THEREOF AND ALSO OF THE ASSOCIATED PRODUCTS
13
PROVISIONAL SPECIFICATION left by the said Francis Bristow Rawes at
the Office of the Commissioners of Patents on the 22nd March 1882.
"IMPROVEMENTS
FRANCIS BRISTOW RAWES of Stratford in the County of Essex
IN AND IN APPARATUS FOR OBTAINING SULPHUR AND SOME OF ITS COMPOUNDS
AND IN THE TREATMENT THEREOF AND ALSO OF THE ASSOCIATED PRODUCTS,"
There are several compounds both natural and artificial, of sulphur with bases
such as gypsum, sulphate of lime, heavy spar, alkali waste, and many others to
which the processes hereinafter described or some or them are applicable as will be
well understood by chemists, reference is made, however, more particularly to
compounds of sulphur with lime (calcium) as a base they being generally more
abundant and available, at the same time including other such bases in combination
with sulphur to which this invention can be applied.
If the compound be a sulphate (gypsum for instance) or in any other state of
combination than that of sulphide and capable of being reduced to the state of
sulphide. I first reduce it to that state (of sulphide) by any known process for
instance in the case of gypsum pulverising and intimately mixing it with carbon
(coal or otherwise) in the proportions of 30 parts carbon or a little in excess thereof
which is desirable to every 100 parts of gypsum and then strongly heating the
mixture in a crucible or a retort or other suitable apparatus for 2 or 3 hours or
longer if the quantity operated upon being large requires it in order that the heat
may permeate the whole mass.
If the compounds operated upon contain any material other than sulphur
and its combined base or bases (calcium or otherwise) such as any accidental or

page_text: occasional admixture or as is ordinarily incident to natural minerals if it be
desirable to separate it because of its value or its detrimental presence, I obtain a
solution from the crude compound (sulphide) in any suitable menstruum-hydro-
chloric acid for instance and according to what may happen to be present in the
compound in any known manner obtain and utilize the bye products, recovering
the base (lime or otherwise) as sulphate by the well known reaction of sulphurio
acid collecting in the usual manner and utilizing the hydrochloric acid driven off.
The sulphate may then be treated as specified in the preceding paragraph.
Calcium chloride a bye product in many chemical operations may be similarly
converted (by sulphuric acid) into sulphate of lime and then be treated as other
sulphates.
To displace the sulphur from combination with its base (calcium or otherwise) I
employ carbon dioxide (carbonic acid) conjointly with an intermedium as a contact
agent and agitation to bring successive particles of the sulphide (in powder in a
suitable vessel) within the influence of the reactions of the carbon dioxide and the
intermedium. The reaction of carbon dioxide upon sulphides is well known but
the use of an intermedium and the employment of agitation (which latter may be
caused by the gas being driven in with sufficient force or by the use of any kind of
commotion from a mechanical stirrer or otherwise) are important aids to the
operation of the affinities bringing the comparatively dense sulphide-molecule by
molecule as it were-into contact with the carbon dioxide gas liberating hydrogen
sulphide and they (intermedium and agitation) are essential features of this invention
as without either one of them the reaction of carbon dioxide gas upon a dry sulphide
is difficult, imperfect and only slightly partial. As intermedium I preferably use
an alkali (as soda) carbonated or supercarbonated and in solution to exclude
atmospheric air, and it is better if the water has been previously boiled to the
intent that the oxidation of the sulphur should be as much as possible avoided.
The carbon dioxide (CO) may be obtained from any source and particularly
from lime kilns or from the combustion of fuel or from both, a sufficient access of air
having been provided to prevent the presence of carbon monoxide (CO) instead of
carbon dioxide any excess of oxygen as far as it is practicable being absorbed
afterwards in any suitable manner preferably by protoxide of iron the resulting
peroxide of iron being afterwards reduced to protoxide by hydrogen sulphide
similar to the processes used at gas works or by any other process and it will be
well by a little attention to the admission of air to the fuel and management by
control of a damper or the like to regulate the supply of air to the fires so that
the excess of oxygen supplied in the air may be easily reduced to a minimum
afterwards. The heat of the gases of combustion may be utilized in cooling them
down to about the temperature of the atmosphere.
As an abundance of carbon dioxide can be obtained at a cheap rate, in some
cases it may be convenient to have a prepared supply of alkali supercarbonated and
so use the requisite quantity of carbon dioxide in a combined form (with the alkali
intermedium) applied to the "sulphide" with agitation and sufficient water to
exclude the air and prevent oxidation. For instance instead of presenting the
carbon dioxide in the state of gas to the "sulphide" and intermedium for the
reactions I may use it in combination with the alkaline intermedium thus to every
72 parts of calcium sulphide (or for other sulphide in the quantity of its chemical
equivalent) take 168 parts of bicarbonate of soda (if that be the intermedium alkali
used) with agitation in a suitable vessel a convenient method being to dissolve in
200 parts of water so much of the soda bicarbonate as that quantity of water will
take up mixing the residue with the sulphide in powder in a suitable vessel of
capacity about equal to contain the mixture and the solution (in 200 parts water)
agitating and heating the whole gradually to boiling until the whole of the sulphur
(or such a percentage thereof as may be economically obtained by the treatment)
be eliminated as hydrogen sulphide. The quantity of water (200 parts) is about
sufficient (at 100° F) to dissolve the whole of the soda when reduced to mono-
Carbon to which results from the treatment, when the reactions are complete the

page_text: solution cleared by settling may be drawn off and the residuum washed in the
usual manner and similarly the liquors may be evaporated and crystallized or
otherwise disposed of.
In the case of alkali "waste" which is a crude sort of sulphide a portion of
unlixiviated black ball" may be added to it, the contained alkali thereby
furnishing the intermedium it may be only partially lixiviated or the calcium
sulphide ("waste") in the black ash may be subjected to the reactions herein
mentioned before or at any stage of the usual lixiviation.
It will be observed that in the foregoing the sulphur is mentioned as being
separated from the "sulphide" in combination with hydrogen, that is, as hydrogen
sulphide and the base (calcium) or otherwise) converted into a carbonate which
with any foreign matter constitutes the insoluble residuum; the intermedium (soda
or otherwise) being soluble can be separated by solution and used again or otherwise
disposed of and the carbonated base may be burned into lime or otherwise utilized;
if to be burned into lime it should be previously mixed with a little clay just
sufficient, with water, to give it coherence in the form of blocks for the kiln. The
hydrogen sulphide may be burned for the vitriol chamber or reduced to free sulphur
by the well known reaction of sulphurous acid or be otherwise utilized in any
known manner.
I now proceed to give a general explanation of the manner of conducting the
processes and a description of the kind of apparatus to be employed, either of
which may be variously modified as I do not restrict myself to the precise details
mentioned.
The vessels to be employed may be conveniently designated "tanks" but may
be of any suitable form dimensions and material and be fitted with closely fitting
covers (a man-bole and cover will answer) pipes, taps, and connections as will be
understood to be requisite and of obvious use, the arrangement being very much
after the manner of the well known "Woulfe's" apparatus and some of them (to
be specified) preferably fitted with an agitator or stirrer of any suitable kind and
provided with a source of heat (steam pipes or otherwise) each inlet pipe (for the
gases) to be of such form and position as to have its delivery end below the surface
of the fluid in the tank (2 or 8 feet) each foot of depth requiring rather less than
half a pound per inch pressure force applied to the gas to be obtained from a
blower" (or fan or otherwise), if the gas be driven into the tanks with con-
siderable force the commotion caused thereby will supply the use of and dispense
with mechanical stirrer, but generally the latter will be the more advantageous of
the two.
The pipe to convey the gas out of the tank (the gas exit pipe) to have its
opening (to receive the gas) in the upper part of the tank, above the contained
fluid the arrangement being generally characterised as being of pipes with one leg
longer than the other and it is obvious that the exit pipe of the first tank will be
the inlet pipe of the second tank and so on in the order of the direction of the
course of the gas through them, that is, if there be a series of tanks which in
preferable (2 or 8 or more) rather than ane tanks of larger size. In addition to the
tanks mentioned and which may be named "desulphuring" tanks there are to be
provided subsidiary vessels. The gas liberated in the vessels (hydrogen sulphide)
is to be directed in its course from the several vessels to the utilizing receptaclo
and as much as possible the docess of air to the gulphides to be prevented.
If the carbon dioxide gas be pure, the "blower" receives it from its source and
forces it into the first of a series "desulphuring tank" each of which has been
charged thus, partly with sulphide in powder and then quite filled up with solution
of super-carbonated alkali (the more it is carbonated the more accelerative to the
reaction) from a contiguous store tank and the cover made tight the connecting
tube with the "store tank" (which should be about the same level) being left open
and the gas exit tube closed the first effect of the gas pressure should be used to
force a little of the solution back into the store tank so as to have a strutum of gas
at the upper part of the desulphuring tanks, the connection with the store tank

page_text: being then closed the gas exit pipe opened and the agitater put into motion the
process goes on and the quicker if the tanks are moderately heated such as by any
available waste heat most of the carbon dioxide is absorbed liberating hydrogen
sulphide which with the unabsorbed carbon dioxide passes out at the exit pipe
into the second desulphuring tank in which more of the carbon dioxide is absorbed
and more hydrogen sulphide liberated which passes into the next tank and so forth
through the series of tanks until the carbon dioxide being completely absorbed
hydrogen sulphide only passes out at the exit pipe of the last tank of the series to
the utilizing receptacle whether it is to be burned for vitriol or otherwise when
the contents of either of the desulphuring tanks (say the first of the series) have
completed the reaction. All the sulphur by the process being eliminated or
practically so much of it as may be economically, suitable arrangements are made
for emptying and recharging it. Altering the connections of the pipes, thus the
gas inlet pipe and the gas exit pipe are closed and the current of the gas conducted
to the second tank direct, by a pipe provided and adjusted for that purpose, the
contents of the first tank are then run out by a pipe provided for the purpose into
a contiguous "settling" tank which is then closed tight and the desulphuring
tank again charged as before and the previous pipe arrangements resumed. After
the settling tank contents have subsided the clear liquor may be drawn off and
the sediment be washed in the usual manner all the liquors being run into a
reservoir of some kind for concentration by evaporation to be used again or
otherwise, the insoluble residuum in the settling tank (which it is better to work
moderately beated) to be dried off and removed for use. As all the liquors usually
retain a little hydrogen sulphide (less if hot) they may be cleared by a little
litharge or other known manner or the vapours of evaporation and such like may
be conducted by a flue or pipe to some adjacent furnace. In washing the sediment
in the settling tanks in practice it will be well to use the water for the first
washing previously to wash out the desulphuring tank, as the whole contents will
not at once be run out clear.
In the case of Alkali waste it may be convenient to arrange the desulphuring
tanks for the double service of lixiviating and afterwards beating the insoluble
residuum (sulphide) or the lixiviation may be made in the usual manner in tanks
contiguous to the desulphuring tanks and the residuum afterwards transferred.
"3
If the carbon dioxide gas be obtained from fuel as previously alluded to, burned
with excess of air the oxygen present should be reduced to a minimum. And it
may be well to wash the gases in the usual manner by first passing them through
water, the gases then may be considered to be nitrogen, carbon dioxide, and
oxygen wbich latter renders a modification of the foregoing process desirable in order
to avoid the oxidation of the sulphide namely I provide a tank, (or a series) into
which the gases are passed previous to the "desulphuring tanks
and the arrange-
ment of the tank may be in the following manner, the tank longer than wide with
a tight fitting cover provided with a transverse diaphragm or partition projecting
about half way down the tank joined to the top and sides, air tight the tank to do
a double service preferably to two tanks, the tank to be supplied with as much
iron oxides as its capacity and the operation will conveniently admit of and then
dilute acetic acid or other weak acid poured in to nearly filling it, the structure of
the tank includes a man hole or otherwise for filling and an exit for occasionally
running out the contents, with pipes (similar to the desulphuring tanks) for
passing in the gases and their passage out and also some contrivance for continually
(when working) transferring the contents from each division to the other for this
purpose two helical revolvers or screws may be arranged longitudinally the whole
length of the tank or thereabouts in the lower part of the tank passing beneath
the diaphragm from the cover, so that one screw continuously moves the contents
of the tank from left to right the other from right to left the operation then will
be the gases being forced into one division of the tank (below the fluid) by a pipe,
the diaphragm (if sufficiently deep) and the fluid prevents them from passing to
the other diyision, the iron absorbs oxygen. And the residual gases pass out at

page_text: the top of the tank division and then into the desulphuring tanks through which
they pass from the last of the desulphuring tanks by a return pipe to the other
division of the tanks (with iron contents) which they enter (below the fluid) and
similarly the diaphragm and the fluid prevent their passage to the other division,
the gases returned from the desulphuring tanks, bave become hydrogen sulphide
and nitrogen and being passed into the second division of the (iron oxides) tank
the sulphur of the hydrogen sulphide is retained the nitrogen passing out at an
exit pipe to the atmosphere or may be utilized The intention of the fluid is to
form with the diaphragm an air tight trap to the gases and the acid slightly
tending to solve the iron and prevent the formation of lumps.
Manganese or other metal may be used with or in lieu of iron. The tank should
be occasionally cleared of the sulphur by a pipe or other suitable means.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Francis Bristow Rawes in the Great Seal Patent Office on the
22nd September 1882.
FRANCIS BRISTOW RAWES of Stratford in the County of Essex
"IMPROVEMENTS
IN AND IN APPARATUS FOR OBTAINING SULPHUR AND SOME OF ITS COMPOUNDS
AND IN THE TREATMENT THEREOF AND ALSO OF THE ASSOCIATED PRODUCTS
"
This Invention refers to a new process and apparatus for treating certain
sulphates for obtaining sulphur in the condition of hydrogen sulphide; also to a
new process or processes and new apparatus for treating compounds namely certain
sulphides and to new apparatus for treating another compound obtained therefrom
viz bydrogen sulphide; also to new apparatus for treating associated products
namely an intermedium liquid and an alkaline solution which results in certain
cases and also carbonate of lime sediment.
There are several compounds, both natural and artificial, of sulphur with bases,
to which the processes hereinafter described or some of them are applicable as will
be well understood by chemists, particular reference being made to the more
abundant compounds of sulphur with lime (calcium) as a base such as “alkali
waste" and lime sulphates.
If the sulphur compound be a sulphate (gypsum for instance) which however is
rarely pure more or less of other matter being present, or in any state of com-
bination with sulphur other than that of sulphide and which nevertheless is capable
of being reduced to the state of sulphide (old "alkali waste" is an example as the
sulphur present in it is generally found to be in a variable state of oxidation some
parts or parcels being oxidated to higher degree than others) I first reduce the
sulphur compound to that state (of sulphide) by any known process for instance;
in the case of gypsum, pulverizing and intimately mixing it with carbon (bituminous
coal for instance in the proportions of 30 parts Bituminous coal or a little in excess
thereof which may be desirable (although in some cases the presence of other
matter such as carbonate of lime may be sufficient in quantity to diminish the
proportion of coal as mentioned which however any chemist will understand how
to regulate) and it may be remarked that the proportion of reducing agent (carbon)
mentioned, is what I consider to be preferable from the tendency of carbon under
the conditions of the reducing process to combine to form carbon monoxide
rather than carbon dioxide) to every 100 parts of gypsum and then strongly
heating the mixture avoiding the contact of air in a crucible, or a retort or other
suitable apparatus for 2 or 3 hours or longer if the quantity operated upon being
large requires it in order that the heat may permeate ithe whole mass or the gypsum
or other sulphur compound may be reduced to the state of sulphide in any other
known manner.
If the compound to be operated upon contains any material other than sulphur
and its combined base or bases (calcium or otherwise) such as any accidental or
occasional admixture or such as is ordinarily incidental to natural minerals which
it is desirable to separate because of its value or because of its detrimental
presence I obtain by any known process a solution from the crude compound
(sulphide and admixture) in any suitable menstruum (bydrochloric acid for instance) 4
and according to what may happen to be present in the compound I in any known
manner obtain and utilize any bye products that may be of value or suitable and
recover the base (lime or otherwise) as "sulphate" by the well known reaction of
treatment with sulphuric acid and heat collecting in the usual manner and
utilizing the hydrochloric acid driven off. The sulphate may then be treated as

page_text: specified in the preceding paragraph. Calcium chloride a bye product in many
chemical operations may be similarly converted (by sulphuric acid) into sulphate
of lime and then be subjected to treatment as other sulphates as mentioned above
for reduction to sulphides.
To displace the sulphur from combination with its base (calcium or otherwise) I
employ carbon dioxide (carbonic acid) conjointly with intermedium (such as will
be mentioned further on) as a contact agent and apply agitation to bring successive
particles of the sulphide (in a suitable vessel the sulphide preferably being in a
pulverous condition or capable of becoming disintegrated in the process) within the
influence of the reactions of the carbons dioxide and the intermedium which
(intermedium) should fill the vessel to the exclusion of atmospheric air.
That carbon dioxide reacts upon sulphides eliminating hydrogen sulphide is
known but the use of an intermedium and the employment of agitation (which
latter may be caused by the carbon dioxide gas being driven in with sufficient
force to disturb the sulphide and to maintain it in a state of commotion in the
intermedium fluid but preferably by a mechanical stirrer any such as will provent
or disturb the aggregation of the particles and cause a constant change of their
place keeping them disturbed about the containing vessel or suspended in the fluid
in such a manner as will mechanically favor the action of affinities and the re-action
of carbon dioxide) are important aids to the operation of the affinities by bringing
the comparatively dense sulphide molecule by molecule as it were into contact with
the carbon dioxide gas to liberate the sulphur (from its base) which entering into
combination with hydrogen forms the well known chemical compound "bydrogen
sulphide"; I also to assist the process prefer to heat the containing vessel any
available heat being used as a temperature of about 100° F. appears to be sufficient
but may be higher.
The operation of carbon dioxide gas upon a mass or bulk of a sulphide (either
dry or moist) is found to be in the processes heretofore tried only partial and very
imperfect and also the presence of atmospheric air (from its oxidating effect) is
most objectionable and therefore the exclusion of atmospheric air and the use of an
intermedium and the employment of agitation are distinguishing features in my
process for treating sulphides with carbon dioxide and each of them is respectively
contributive, but the conjoint use and employment of all in the aforesaid treatment
is the more complete process.
For the intermedium I preferably use an alkali (as for instance soda for soda
waste potash for potash waste) carbonated or supercarbonated and in solution to
exclude atmospheric air from contact with the sulphide during the process, as it is
important to obviate the ready tendency of sulphides to oxidation. The solution
may be a saturated solution or thereabouts of super carbonate and it is better if
the water for the solution has been previously boiled so as to eliminate the air to
the intent that oxidation of the sulphur should be as much as possible avoided.
The carbon dioxide (00) may be obtained from any source and particularly from
Hme kilns or from the combustion of fuel or from both, a sufficient access of air
having been provided to prevent the presence of carbon monoxide (CO) instead of
carbon dioxide the remaining or uncombined oxygen being as far as is practicable
afterwards absorbed or otherwise got rid of or reduced to a minimum in any suitable
manner; such a mixture of gases passed through protoxide of iron yields some of
its oxygen to the iron, it becoming sesquioxide which may be again reduced to
protoxide by hydrogen sulphide according to reactions practised at gas works, or
the carbon dioxide may be separated from such mixed gases and be afterwards
utilized in the manner and apparatus hereinafter described and it will be well by
a little attention to the admission of air to the fuel and management by control of
a damper or the like to regulate the supply of air to the fires so that no more
excess of oxygen be supplied (in the air) than is requisite for perfect and complete
combustion of the fuel so that afterwards it may be the more easily reduced to a
minimum. The heat of combustion of the gases may be utilized while cooling
them down to about the temperature of the atmosphere,

page_text: As an abundance of carbon dioxide can be obtained at a cheap rate it may be
convenient in some cases to have a prepared supply of alkali supercarbonated so as
to use the requisite quantity of carbon dioxide in a state of combination (with the
alkaline intermedium) applied to the sulphide with agitation in a close vessel and
sufficient water to exclude the air in order to prevent oxidation the process being
assisted by heat. For instance instead of presenting the carbon dioxide in the
state of gas to the sulphide and the intermedium, for the re-actions, it may be used
in combination with the alkaline intermedium, thus to every 72 parts of calcium
sulphide (or for other sulphide in the quantity proportionate to its chemical
equivalent) take 168 parts of bicarbonate of soda (if soda be the intermedium
alkali used, any other alkali in quantity proportionately to its chemical equivalent)
with agitation in a suitable vessel arranged so that it may be heated, a convenient
method being to dissolve in 200 parts of water so much of the soda bicarbonate
(the before mentioned 168 parts) as that quantity of water will take up mixing
the residue of the soda bicarbonate (the mentioned 168 parts) with the sulphide in
powder in a suitable vessel of a capacity about equal to contain the mixture and
the solution (in 200 parts water) agitating and heating the whole (gradually to
obviate the decomposition of the bicarbonate and dispersion of the carbon dioxide
before it has had time to react upon the sulphide) until it boils and containing
until the whole of the sulphur (or such a percentage thereof as may be economically
obtained by the treatment) be eliminated as hydrogen sulphide which is to be
collected for use the same as that obtained in any other manner. The quantity of
water (200 parts) is about sufficient (at 100° F.) to dissolve the whole of the soda
(when reduced to monocarbonate which results from the treatment, when the
re-actions are complete) and the solution, cleared by settling, may be drawn off and
the residuum washed in the usual manner and similarly in the usual manner the
solution and washings may be evaporated concentrated and crystallized or otherwise
disposed of.
In the case of "alkali waste" which is a crude sort of sulphide a portion of
unlixiviated "black ball" may be added to it, the contained alkali of which (with
water) will dissolve out and obviate the addition of other intermedium, or the
black ball" may be only partially lixiviated, or the calcium sulphide (waste) in
"black ball" may be subjected to the re-actions hereinmentioned (in suitable
vessels) during any stage of the usual process of lixiviation.
It will be observed that in the foregoing the sulphur is mentioned as being
separated from the sulphide in combination with hydrogen that is as hydrogen
sulphide, a well known mechanical compound and the base (calcium or otherwise)
converted into a carbonate which with any foreign matter (if any) constitutes the
insoluble residuum; the intermedium (soda or otherwise) being soluble can be
separated by solution and used again or otherwise disposed of and the carbonated
base may be burned into lime or otherwise utilized if to be burned into lime it
should be previously mixed with a littly clay just sufficient with water to give it
coherence in the form of blocks and then dried for the kiln. If the sulphide to be
desulphured be "alkali waste" with an aimixture of "black ball" or if it be
"black ball" wholly which has not been lixiviated in the usual manner then the
resulting products that is to say the solution and the lime carbonate sediment will
generally have associated with them compounds such as in the usual treatment
would have passed out with the lixivium of the "black ball" & such lixivium
usually contains (besides other saline compounds) much caustic alkali which
becomes carbonated in the desulphuring tank, I in such case use the solution if
desired as an intermedium but only so often or until the accumulation of saline
compounds has become objectionable. I then add the washings of the sediment
evaporate to dryness dissolve and crystallize in the usual manner.
"
The washed lime carbonate sediment from the said black ball" treatment I
prefer to treat with alkaline bydrate in the tank S** or other suitable vessel to
dissolve up alumina bydrate (if any) that may have become insoluble by the
carbonating process and may have deposited and the solutions may be concentrated

page_text: in the usual manner and disposed of as aluminate of soda for instance or otherwise.
The hydrogen sulphide may be burned or heated in contact with atmospheric air
or oxygen, the resulting sulphurous acid may be utilized in the vitriol chamber or
for other purposes or the hydrogen sulphide may be converted or reduced to free
sulphur by the well known method or re-action of sesquioxide of iron similar to
the practice at gas works or by the reaction (as known) of sulphurous acid or be
otherwise treated or utilized in any known manner.
I now proceed to give a general explanation of the manner of conducting the
processes and a description of the kind of apparatus to be employed either of
which may be variously modified as I do not restrict myself to the precise details
mentioned.
The vessels to be employed may be conveniently designated "tanks" but may
be of any suitable form dimensions and material and be fitted with closely fitting
covers (a manhole and cover will answer) pipes taps and connections as will be
understood to be requisite and of obvious use, the arrangement being very much
after the manner of the well known "Woulfes" apparatus and some of them (to be
specified) preferably fitted with an agitator or stirrer of any suitable kind and by
preference provided with a source of heat (steam pipes or otherwise) each inlet
pipe (for the gases) to be of such form and position as to have its delivery ends
below the surface of the fluid in the tank (3 or 4 feet or more) each foot of depth
requiring rather less than half a pound per inch pressure force applied to the gas
which pressure may be obtained from a "blower" (or fan or otherwise). If the
gas be driven into the tanks with considerable force the commotion caused thereby
may supply the use of and dispense with mechanical stirrer but generally the
latter will be the more advantageous of the two. Each pipe for the conveyance
of gas out from the vessels or tanks (the gas exit pipes) to have its opening (to
receive the gas) in the upper part of the tank above the contained fluid, the
arrangement being generally characterised as being of pipes with one leg longer
than the other (or syphon pipes) the longer leg descending beneath the surface of
the fluid for the delivery of the gas into the fluid in the manner well understood
and it is obvious that the exit pipe of the first tank (of a series) will (in its longer
leg) be the inlet pipe ¿.e. the delivery pipe of the gas to the second tank (of a
series) and so on in the order of the direction of the course of the gas through
them, that is, if there be a series of tanks which is preferable (2 or more) rather
than one tank of larger size. In addition to the tanks mentioned and which may
be named "desulphuring tanks" there are to be provided subsidiary vessels for
uses hereinafter described. The gas liberated in the vessels (hydrogen sulphide) is
to be directed in its course from the several vessels to the utilizing receptacle and
as much as possible the access of air to the sulphides and the escape of the hydrogen
sulphide into the atmosphere to be prevented.
If the carbon dioxide gas be pure the "blower" receives it from its source and
forces it into the first desulphuring "tank," if a series, each of which has been
charged thus, partly with sulphide in powder or condition to disintegrate and then
quite filled up with solution of supercarbonated alkali (the more it is carbonated
the more accelerative to the re-action), from a contiguous store tank or reservoir
and the cover made tight, the connecting tube with the store tank (which should
be about the same level or a little higher) being left open the top of the gas exit
tube closed and the tap of the gas delivery tube open the first effect of the gas
pressure should be used to force a little of the solution back into the store tank so
as to have a stratum of gas at the upper part of the desulphuring tank the con-
nection with the store tank or reservoir being then closed the gas exit pipe opened
and the agitator put into motion the process goes on and the quicker if the tanks
are heated (moderately as no apparent advantage is to be derived from the
generation of a large quantity of steam) such as by any available waste heat, most
of the carbon dioxide is absorbed, liberating bydrogen sulphide which with the
unabsorbed if any carbon dioxide passes out at the exit pipe into the second (of a
series) desulphuring tank in which more of the carbon dioxide is absorbed and

page_text: more hydrogen sulphide eliminated which passes into the next tank and so forth
through the series of tanks until the carbon dioxide is absorbed (or nearly all
absorbed in fact I find that very little carbon dioxide escapes absorption in the
first tank and so two tanks will generally be sufficient and it may be economical
to allow a small percentage to escape and hydrogen sulphide only (or with a small
percentage of carbon dioxide) passes out at the exit pipe of the last tank of the
series to the utilizing receptacle whether it is to be burned for vitriol or otherwise.
When the contents of either of the desulphuring tanks (say the first of the series)
have completed the reaction all the sulphur, by the process being eliminated from
the calcium (lime) or practically so much of it as may be economically suitable to
recover, arrangements are made for emptying and recharging it, first altering the
connections of the pipes; thus the gas inlet pipe and the gas exit pipe are closed
and the current of the gas conducted direct to the second tank (of a series) by a
pipe or pipes provided and adjusted with taps and connections suitable for that
purpose then the contents of the first tank are run out by a pipe provided for the
purpose into a contiguous settling tank which pipe is then closed tight and the
desulphuring tank again charged as before and the previous pipe arrangements
resumed it may however be convenient in practice to alter the arrangement of the
opened and the closed taps so that alternately each tank (supposing there are two)
is made to be the first of the series in a manner easily understood. After the
settling tank" contents have subsided the clear liquor may be drawn off and the
sediment be washed in the usual or any suitable manner all the liquors being run
into a reservoir of some kind to be used again or for concentration by evaporation
or otherwise and the insoluble residuum in the settling tank (which it is better to
work moderately heated) removed and disposed of. As all the liquors usually
retain a little bydrogen sulphide (less if hot) they may be cleared by a little
litharge or in any other known manner or any exhalation of hydrogen sulphide
may be conducted into the general receptacle of that gas or the vapours of
evaporation and such like as hydrogen sulphide exhalation may be conducted by a
flue or pipe to some adjacent furnace. In washing the sediment in the settling
tanks, in practice it may be well to use the water for the first washing (if several
washings be preferred) previously to wash out the desulphuring tank as the whole
contents will not at once be run out clear.
In the case of alkali waste it may be convenient to arrange the desulphuring
tanks for the double service of lixiviating and afterwards treating the insoluble
residuum (sulphide) therein or the lixiviation may be made in the usual manner in
tanks contiguous to the desulphuring tanks and the residuum afterwards
transferred.
If the carbon dioxide gas be obtained from fuel as previously alluded to burned
with excess of air, the oxygen present should be reduced to a minimum and it may
be well to wash the gases in the usual manner by first passing them through water
The gases then may be considered to be a mixture of nitrogen carbon dioxide and
oxygen the presence of which latter gas requires particular attention so that the
quantity admitted to the sulphide may be reduced to a minimum (in order as
much as possible to avoid the oxidation of the sulphide) or be entirely got rid of.
It is well known that chalk &c treated with acid yields an approximately pure
carbon dioxide but its expense is an objection to its use. I however obtain an
approximately pure carbon dioxide (by a process hereinafter described) which may
be used for eliminating the hydrogen sulphide without introducing to the sulphide
an appreciable quantity of oxygen. But advantage may if desired be taken of the
tendency of some metallic oxides (iron for instance) to absorb and combine with
more oxygen when presented to them to diminish the presence of oxygen in gases
of combustion to a minimum; such oxides for instance protoxide of iron in the
presence of oxygen oxidises to sesquioxide which in the presence of hydrogen
sulphide becomes again protoxide iron; reactions well understood and practised at
some gas works by alternately forcing in atmospheric air and the sulphuretted gases,
pp application of which principle I employ as follows. I provide a tank or a series

page_text: of tanks, into and through which the flue gases are passed or forced previous to
their entering the desulphuring tanks and the arrangement of them may be in the
following manner; the tanks to be about square in transverse section and to be in
length about twice the width, to be provided with a tight fitting cover and at
about mid length a transverse partition or diaphragm projecting about half way
down the tank and be fixed airtight to the top and sides (that the tank may do
double service without removing the contents or shifting the connections) the
contents of each tank to be iron (a mixture of protoxide and sesquioxide will do)
and in quantity suitable to the capacity of the tank (about one sixth in bulk) and
nearly filled with water or weak acid. The construction of each tank to include
manhole or otherwise for filling and pipes for gases and an exit pipe for emptying
as occasion may require and also some contrivance for continually (whilst the gases
are being passed through) transferring the contained iron oxides from either one
division to the other. I prefer two revolving screws arranged horizontally
longitudinally the entire length of the tank (or thereabouts) in the lower part
thereof and just passing free and beneath of the aforementioned diaphragm the
screws to be connected with gearing (outside the tank) by axles or spindles passing
through stuffing boxes and arranged to revolve in contrary directions the one
moving the contents (iron oxides) from left to right the other from right to left and
this will be assisted by a longitudinal vertical part division between the two screws
but to control the direction longitudinally rather than sideways The conduct of
the operation is as follows: the gases are forced into one division of the tank (one
of the divisions separated by the diaphragm) by a pipe passing below the fluid and
delivering the gases near the bottom of the tank and any similar arrangement for
distributing the gas as that hereinafter mentioned in respect of the desulphuring
oylinders may be adopted. The diaphragm (which must be sufficiently deep)
together with the fluid in the tank "traps" the gases and prevents them from
passing to the other division of the tank the protoxide of iron absorbs oxygen and
becomes sesquioxide, the residual gases (which may be considered to be nitrogen
carbon dioxide and a diminished proportion of oxygen) pass out by a pipe at the
top of the tank (in the division of the tank whereat they entered) and then
similarly through a division of each tank (if a series) to the last tank whence the
gases pass into the desulphuring tank or tanks (if a series) through which they
pass in the usual manner entering by a pipe delivering the gas beneath the fluid
and the gas escaping by an exit pipe in the upper part. Thence (from the last of
the desulphuring tanks by a "return pipe" they re-enter the tank (or tanks if a
series) which has a diaphragm for forming two divisions therein and contains iron
oxides as explained above The gases enter (below the fluid), and being similarly
as before "trapped" by the diaphragm and the fluid their passage to the other
division of the tank is prevented, but they are allowed to pass out in the usual
manzer from the upper part of the tank by an exit pipe. The gases returned from
the desulphuring tanks (to the tank or tanks having diaphragm divisions and
containing iron oxides), and having therein parted with carbon dioxide (to the
sulphide) and become (by the substitution) chluffy bydrogen sulphide and nitrogen,
In order to separate the sulphur from the hydrogen by the forementioned iron
reactions the gases are passed into the second division of the tank (containing iron
oxides) that is to say into the division of the tank that was avoided by the gases
when in the first instance they were passed through the tank (or tanks) and in
practico it will be well to regulate the admission of the gases forced through the
apparatus by the use of a tap or valve or by adjusting the motion of the blower to
the absorbing or decomposing rate or capacity of the iron oxides (provided for the
purpose of effecting the well known decomposition or reactions) so that no
bydrogen sulphide be allowed to escape at the exit pipe to the atmosphere as the
presence of hydrogen sulphide can be easily detected chemically for instance, paper
inoistened with lead acetate becomes dark coloured. The rate of the reaction of the
sesquioxide of iron upon hydrogen sulphide has generally been found to diminish
as free sulphur acoumulates.

page_text: "
The sulphur of the hydrogen sulphide is thus as free sulphur all or nearly all
retained, the residual gases chiefly nitrogen passing out at an exit pipe to the
atmosphere or may be utilized if any suitable manner presents itself. The office
or use of the fluid in the tanks is with the diaphragm to form a gastight trap to
the gases, so that in passing through a series of tanks the operation of the oxygen
of the admixed atmospheric air may be limited as much as possible to the half of
the tank which they are directed through, in order that the iron protoxide should
freely absorb oxygen and become sesquioxide in the one division, and then by a
sufficient motion of the "screws or other stirring action, the sesquioxide, being
transferred to the other division may be acted upon by the hydrogen sulphide and
reduced to protoxide again. Manganese or other suitable metal may be used with
or in lieu of iron. The contents of each tank will require to be occasionally run
out at a pipe or otherwise to separate the free sulphur from the iron oxides which
may be done by solution of the sulphur in bisulphide of carbon (as is a well known
method) recovering the sulphur and the bisulphide of carbon separate, by distillation
or separate the sulphur from the iron oxides by sublimation or other convenient
method.
The method for obtaining for use approximately pure carbon dioxide as referred
to above from gases of combustion or lime kilns is as follows:-I pass the gases
through a suitable vessel (or a series) in which there is an absorbent of carbon
dioxide such as a strong or saturated cold solution of mono-carbonate of soda or
potash or a mixture, the vessels being kept cool by running water round them or
otherwise during the passage of the flue gases, the carbon dioxide is absorbed and
the super-carbonated soda or other alkali being less soluble deposits, the oxygen
nitrogen &c. escaping by an exit pipe the fluid may when the process is completed
be drawn off (to be used to dissolve more soda or otherwise) and about half of the
carbon dioxide gas driven off by heat or this may be varied by the accumulation
of supercarbonate from several successively treated solutions (of mono carbonate
with carbon dioxide) before it is heated for driving off free carbon dioxide, or the
carbon dioxide may be driven off by heat without drawing off the solution from
the vessel a process that requires no particular directions to a chemist.
In the accompanying drawing some parts are shown single and some parts are
shown in pairs and in the explanation thereof the description corresponds but they
are not thereby necessarily limited thereto as it will readily occur to the
manufacturer that some of the parts may be varied in number or otherwise
modified in details dimensions proportions or in any other manner that circum
stances may require or suggest and any suitable materials may be employed it
being simply my aim to plainly indicate that which according to the best of my
judgment I consider to be the best manner or method of carrying into effect the
aforementioned process or processes more particularly and fully that which I
consider to be a main feature or central element of the same namely the
dissociation of sulphur from its base as hydrogen sulphide by the treatment with
carbon dioxide And similarly to eliminate complexity as much as possible I omit
from the drawing such parts as gearing and other parts the use and arrangement
of which can be obviously apprehended and the form position, and relations of
which can be readily supplied by ordinary engineering experience and may be
adapted to suit any existing plant.
Regarding the most economical source of carbon dioxide (CO₂) to be flue gases
or lime kiln vapours their heat may be utilized to eliminate carbon dioxide (derived
from a previous operation) in the manner about to be described i.e. I first use any
available heat of such gases and then when sufficiently cooled (in any manner)
I obtain from them a supply of carbon dioxide. The gases from the flues or such
like (which may be regarded as a mixture of carbon dioxide nitrogen and air) pass
into a purifying tank or apparatus illustrated at Figures 1. 2. 3 and 34, figure 1-
being a vertical cross section half on line & a and half on line y y and figures 2
au 3 longitudinal vertical section of the carbon dioxide purifying tank, the one
showing the horizontal flue pipes in full lines with the vertical pipes dotted, the

page_text: other showing the vertical in full lines with the horizontal dotted and Figure 34
being a horizontal section at ab (the horizontal flue pipes being arranged somewhat
after the manner of a locomotive boiler) The gases pass by the pipe A into the
space B beneath D (which forms the bottom of the tank proper it being a close
vessel with the exception of the pipe openings and is provided with tapped
apertures for pouring in and for drawing off fluid) and in the direction of the
arrows the gases follow along E F G and out at H whence the flue gases may be
conducted through a second of a series of such vessels to warm the tank and
contents and to further lower the temperature of the gases; and the gases may be
used alternately with a series of carbon dioxide purifying tanks the partially cooled
gases being used to warm a tank to be followed by fresh hot flue gases to heat it
to the requisite temperature or the gases may in succession be passed through
more than two tanks after which they may be further cooled in any manner such
as by passing them through a pipe (or worm) in water to the temperature of the
air, or cooler being desirable, and then (when sufficiently cooled) the gases may be
conducted through the several divisions in one of the tanks shown by the vertical
lines (Figure 3) entering the tank at J and out of the first division by the bent
pipe at K and into the second division and so forth in succession through each
division, and the gas delivery pipes may have the same arrangement for
distributing it as is mentioned hereafter in relation to the desulphuring
cylinders (which may be of any convenient number) to the exit at M (or
in a similar manner through several such tanks). In connection with
pipe J
a blower may be conveniently placed to act in part as an
exhaust from the horizontal flues E F G and to force the gases through the tank
as described. The gases at J being carbon dioxide nitrogen and air the tank is to
be nearly filled with a strong or saturated solution of soda monocarbonate (or
other absorbent of carbon dioxide or potash or a mixture nor need they be
chemically pure) which by absorbing the carbon dioxide becomes a less soluble
super-carbonate and subsides from solution, little less than the nitrogen and the
air escaping at pipe M into the atmosphere. During the time the carbon dioxide
is being absorbed it is desirable to keep the temperature of the tank low, which
may be done in various ways and it may be convenient for that purpose to connect
the flue pipes E F and G by suitable taps and pipes with a source of cold water
to be run through them. When all or nearly all the soda in the tank has become
supercarbonate the solution may be run out and may be again used to dissolve
soda monocarbonate (which may be the monocarbonate reduced by a previous
treatment of supercarbonate or otherwise) to be similarly supercarbonated and the
residoum in the tank of subsided supercarbonate have about half its carbon
dioxide driven off by heat (the temperature of boiling water to about 300° F.
I consider to be suitable but generally the extraction of carbon dioxide is
accelerated by increase of temperature) from any source or preferably in the manner
specified above by the flue gases being passed through the tubes E F G the soda
supercarbonate being reduced to monocarbonate thus the monocarbonate is super-
carbonated by passing the cooled flue gases through tank by pipes J to M then
the carbon dioxide is driven off by the heat of the hot gases or flame being passed
through pipes E to H then the solution from a previous operation may be run
into the tank to dissolve up the soda reduced to monocarbonate and so on round.
It may however be a desirable modification in some cases to obtain an accumulation
of supercarbonate in a tank by treating, with carbon dioxide in the manner
described, several successive solutions of monocarbonate and then (when sufficient
is obtained) as precipitated or subsided supercarbonate) driving off the carbon
dioxide as described.
Figure 4 is a plan and Figure 5 a side elevation and part section through the
centre excepting that for plainness the pipe B1 is shown as though it was in the
same straight line instead of being at an angle, and R' is wide of the central line
of parts generally corresponding. When the carbon dioxide is to be driven off as
described from tank (Figures 2 and 8) the pipe M is connected with pipe N

page_text: .
(Figures 4 and 5) at which point a blower may be conveniently adjusted and the
carbon dioxide forced in the course indicated by the arrows along pipe O whence
it descends by the two vertical pipes P P placed in the margin of the desulphuring
cylinder Q and passing to nearly the bottom of the cylinder. Figure 6 is a part
section on a larger scale showing the relations of the pipes OO with the bottom
portion of the cylinder where the carbon dioxide passes into the cylinder at which
place the smaller ring of the cylinder passes a little distance within the larger and
bottom ring of the cylinder (at a Figure 6) sa as to form a vertical rim projecting
downwards all round the cylinder providing a kind of reservoir for the carbon
dioxide so that it may enter the body of the cylinder at any part of its circum-
ference. The carbon dioxide may however be conducted into the cylinder at any
other part and any other method favourable to its distribution may be adopted in
connection with the construction of the gas delivery tubes. The tanks Q¹and Q
being charged with sulphide (as hereinafter described) carbon dioxide is absorbed
and hydrogen sulphide eliminated which with any unabsorbed carbon dioxide
passes to the upper part of the tank and out by the pipe S Figures 4 and 5 into
pipe V (Figure 4) thence by pipe W to pipe X whence it descends by two pipes
(similar to pipes P P in Q¹) into Q where any carbon dioxide present will be
further absorbed and hydrogen sulphide liberated the course of the gases will
thence be (similarly to Q¹) by an ascending pipe to Z whence the course is by B
and B' to Y where it is directed downwards into a tank or vessel d which is
similar to Figure 3 but without the horizontal flue pipes and is fitted with one or
more vertical divisions and syphon pipe or pipes to contain an absorbent of
carbon dioxide (soda monocarbonate solution for instance) adapted to retain all
or nearly all of any carbon dioxide that may be remaining mixed with the gas or
gases passed through it; thence the approximately pure hydrogen sulphide issues
from e and may be conducted into any suitable receptacle to be reduced to free
sulphur by any known manner or process or as herein described or otherwise
utilized or disposed of.
The taps, pipes and connections are so arranged that the current of the gases can
be directed in such a manner that each tank may alternately have the priority the
taps turned on and the taps turned off regulating the course as may be observed
by an examination of the drawing (Figure 4) and also whilst either of the tanks
is being recharged with sulphide it can be shut off or isolated from the current of
the gases. When a tank (say Q') is to be charged with sulphide the taps b, c, d, e, f, g
Figure 4 and h Figure 5 are closed (such other taps being opened as will direct the
course of the gases from N (Figure 4) to tank Q, and through B and B¹ to Y and
out at e) a conveniently working quantity of sulphide is then put in at the
manholes j, Figure 4 upon the false bottom o Figure 5 which is preferably but not
necessarily curvilinear, the manholes jare then to be closed tight and the taps g
and k Figure 4 and p Figure 5 opened so that the intermedium may flow from
the reservoir R¹ to fill up the tank expelling the air at tap p Figure 6 (or a pipe
having a tap may connect the top of the cylinder with the top of the reservoir)
the pipe p is also to shew when the cylinder is full by fluid instead of air escaping
thereout when it is to be immediately turned off, the gas from N Figure 4 is then
turned into the cylinder by tap 6 (tap & being turned off) until the gas pressure
forces a portion of the intermedium back into the reservoir R' and the surface in
the cylinder depressed about two inches to be ascertained by a gauge in the
cylinder similar to that used for steam boilers (not shown in the drawing); the
tap g is then turned off and the other taps turned so as to direct the gas through
first one tank then through the other (and so forth out by the usual course, the
agitator is then put in motion and rotated until the sulphide is desulphured to
the extent required, which a little experience will generally inform of the requisite
time but a sample may be drawn at tap m Figure 4 (provided for that purpose)
and tested chemically.
When the contents of a tank is considered to be sufficiently desulphured (say Q')
the gas is turned off by taps o Figure 4 and Figure 5 (the course of the gas being

page_text: rectified by the other taps) and tap p Figure 5 opened, the contents are well stirred
up (by a rapid motion of the agitator) and then run by tap f Figure 4 into the
settler Sx and the tap f closed the other taps being adjusted, the tank Q¹ can be
recharged. When the contents of settler Sx have subsided, the clear liquor is to
be pumped up into reservoir R¹ and then water (batter if warm) run into the
Bettler and the whole well agitated by a stirrer (provided for that purpose) run
out at pipe n Figure 5 into settler Sxx and allowed to subside. The clear liquor
being drawn off may be used as a washing, several times, and then added to one
of the Reservoirs R' to compensate for waste by evaporation &c. and the sediment
shovelled out into barrows to be dried or otherwise disposed of, or the bottom of
the settler Sxx may be provided with openings having close fitting sliding covers
which by being drawn aside will allow the sediment to fall into barrows or trucks
for removal. The sediment may however be dried in the settler if preferred.
When "black ball" sulphide is treated as above described the manner of settling
and washing is modified as mentioned above.
Taps t and u are provided that any exhalation of hydrogen sulphide from the
settlers may be admitted to the general channel of the gas and test taps for
obtaining samples of the passing gases may be placed at any requisite place.
o, Figure 5 is a false bottom, or grating, or perforated division (about midway I
prefer) on to which the sulphide is charged, the opening of the perforations or
distance between the gratings may be about half an inch. Down the centre passes
through a stuffing box the shaft or axle of the agitator carrying from its upper
part, projecting arms, from which, awing suspended and moving freely (hinge-like)
distributors A which in revolving gradually abrade (chiefly by their weight) the
heaps of sulphide and distribute it about the tank, the smaller particles passing
from time to time beneath, the dimensions and form of the distributors being
regulated to allow them to pass freely within the tanks when swinging horizon-
tally. At the bottom are stirrers A' firmly attached to the shaft or axle, these
are of two forms the one moulded something after the fashion of a screw propeller,
by its revolution as a sort of scraper, stirs up the subsiding sulphide, tanding by
its scythe-like form (in plan) to gather the sulphide about its middle (where it has
less altitude and in passing deposits it thereabouts, some counteracting effect to
the tangential force of revolution being thereby obtained) the form of the other
stirrers may be described as being a strong frame carrying "louvre boards "
(preferably metal) at an angle of about 60°, the tangential force of revolution being
to the circumference, the deflecting operation of the "louvre boards" is towards
the centre. Figure 7 is a borizontal section or plan of the two forms of stirrer
arms and Figure 8, shows vertical sections of the scraping stirrer as made at either
and and at midway.
I prefer to arrange all the pipes (so far as is possible or desirable) with movable
covers to openings provided at those parts of the pipes wheir their direction is changed
(angles &o) so that axamination may be had and any obstruction easily removed.
Figure 8 is a plan view and figure 10 a part section on line Y, Z, and part side
elevation of an apparatus for peroxidising protexide of iron and for reducing or
decomposing hydrogen sulphide to free sulphur. Figure 11 is vertical transverse
section of one of the tanks, and, Figure 12 plan section, also for peroxidizing the
protoxide of iron. T T T &c are tanks each having a vertical diaphragm a in the
upper part and pipes for inlet and outlet of the gases. The inlet pipe reaches nearly
as low as the diaphragm. U U are screws provided in the bottom of each tank and
receiving revolving motion for the purpose of effecting a constant change of the con-
tents from either one part of the tank to the other as stated above. V is a partition
between the screws for preventing them interfering with the action of each other.
The construction uses and arrangement of the other parts of the apparatus so far as
shown are similar to that described with reference to figures 4 to 8 with exception of
the "return" pipe shown at E, and the parts not shown must obviously be supplied.
The pipe A receives the flue gases and conducts them into one division of the
tanks T T &c which tanks are charged with iron oxide and water or weak acid;

page_text: the gases descend by the syphon leg inlet pipe A¹ passing out by the outlet pipe A³
then descending by the syphon leg end of the latter and so on through the whole
series; passing out by the pipe O which conducts it to the desulphuring system of
pipes and tanks Q'Q' from which the gases by the return pipe E pass to the tanks
TT &c and through the second divisions of same by pipes B¹ and B' passing
successively through the series.
The arrangement of the syphon inlet pipes A¹ and of the outlet pipes A* is
opposite, on the two opposite sides of the tanks T T &o the inlet pipes A¹ being on
the left, on the upper or further side, and on the right, on the lower or nearer side
as indicated by the lettering. The gases entering consist mainly of nitrogen,
carbonic acid and air; while traversing the series of first divisions they part with
oxygen thus converting the iron protoxide into sesquioxide; they then during their
passage through the desulphuring tanks Q'Q' part with their carbonic acid
eliminating hydrogen sulphide which latter together with the other remaining
gases by the return pipe E pass into and traverse the second division of the tanks
TT &c. by the pipes B¹ B³.
During this passage the hydrogen sulphide re-acts on the sesquioxide of iron
liberating free sulphur and reducing the sesquioxide into protoxide. The screws
UU during the process are operating so as to transfer the protoxide which has been
produced in one division of a tank T into the other division of the tank to be there
peroxided by the atmospheric air passing through it and similarly the peroxide is
passed back into the other division to be there reduced to protoxide and free
sulphur by the hydrogen sulphide reaction
I claim-
First: The combined process for converting certain sulphates into hydrogen-
sulphide consisting in first reducing the sulphate into a sulphide such as stated by
heat and by contact with the reducing agent or mixture in a closed vessel pre-
cautions being taken for excluding the air and thereupon treating the sulphide so
obtained with carbon dioxide in a closed vessel containing an intermedium precautions
being taken for excluding the air and with agitation all substantially as set forth.
Second: The process for producing hydrogen sulphide from a sulphide such as
stated consisting in treating the latter with carbon dioxide in a closed vessel con-
taining an intermedium precautions being taken to exclude the air and with agitation
all substantially as set forth, also the alternate process in which the carbon dioxide
is combined beforehand with an alkaline intermedium
Third: The construction and combination of parts forming the improved apparatus
for purifying erude carbonic acid gas and utilizing its heat or not all substantially
as described with reference to Figures 1, 2, 3 and 3ª.
Fourth-The construction and combination of parts forming the apparatus for
obtaining hydrogen sulphide from a sulphide all substantially as described with
reference to Figures 4 to 8.
Fifth-The construction and combination of parts forming the apparatus for
treating hydrogen sulphide with iron oxides for obtaining free sulphur, substantially
as described with reference to Figures 9 to 12.
Sixth-The use of the products and of the bye products obtained by the processes
or treatment substantially as herein set forth and described.
In Witness whereof I the said Francis Bristow Rawes have hereunto set my
hand and seal this Twenty second day of September in the year of our
Lord One thousand eight hundred and eighty two.