IMPROVEMENTS IN OBTAINING FROM ALKALI WASTE EITHER FREE SULPHUR, OR FREE SULPHUR AND SULPHUROUS Acm OR IND AN art
Year: 1883

page_text: LETTERS PATENT to Carl Friedrich Claus, of Mark Lane in the City of
London Chemist. for an Invention of "IMPROVEMENTS IN OBTAINING FROM
ALKALI WASTE EITHER FREE SULPHUR, OR FREE SULPHUR AND SULPHUROUS
Acm OR IND AN art bas
PROVISIONAL SPECIFICATION left by the said Carl Friedrich Claus at the
Office of the Commissioners of Patents on the 31st December 1883.
CARL FRIEDRICH CLAUS of Mark Lane, in the City of London, Chemist,
"IMPROVEMENTS IN OBTAINING FROM ALKALI WASTE EITHER FREE SULPHUR, OR
FREE SULPHUR AND SULPHUROUS ACID, OR FREE SULPHUR AND SULPHURETTED
HYDROGEN
»
This invention consists in a method of obtaining from the residual product of the
manufacture of soda by the Leblanc process, without the use of hydrochloric acid,
either free sulphur, or free sulphur and more or less sulphurous acid, or free sulphur
and more or less sulphuretted hydrogen.
The said residual product, commonly known as "alkali waste," consists
essentially of calcium sulphide, and the first of the two operations which
collectively constitute the present invention consists in mixing the said residual
product with water, charging the mixture into closed vessels, and injecting thereinto
carbonic acid gas, mixed or not with other gases, whereby the calcium sulphide
of the said residual product is converted into calcium carbonate and its sulphur
is driven off as sulphuretted hydrogen. If pure carbonic acid gas be used in this
operation, the operation may be so conducted that the resulting sulphuretted
hydrogen shall be free or nearly free from admixture with other gases; but it will
frequently be more convenient to use in this operation the gases from limekilns, or

page_text: products of combustion, in which case the sulphuretted hydrogen obtained will be
diluted by other gases.
The second of the said two operations consists in adding to the sulphuretted
hydrogen, or mixture of sulphuretted hydrogen and other gases, obtained as just
said, such quantity of air that there shall then be present with the resulting
mixture of gases either just the quantity of free oxygen, or something more or
something less than the quantity of free oxygen, necessary to burn the hydrogen of
the sulphuretted hydrogen, according to the reaction:
H, SO H₂O + S,
=
and in then passing the mixture of gases now containing sulphuretted hydrogen
and free oxygen in the said proportions through a bed or layer of pieces or
fragments or powder of solid material maintained at a suitable temperature either
by the heat of the resulting reaction of the oxygen of the said mixture of gases
upon either more or less of the hydrogen only or upon the hydrogen and also more
or less of the sulphur of the sulphuretted bydrogen of that mixture of gases, or by
heat from other sources, or partly by the one and partly by the other, as will be
explained below. The result is, according to the proportion of air used, that either
the whole of the sulphur of the sulphuretted hydrogen is set free, or that part of it
is set free, the remainder of the sulphuretted hydrogen either passing off in the free
state, or being burned into sulphurous acid and vapour of water, as may be
preferred in each case.
"
The first of the two operations which collectively constitute the present invention
may conveniently be performed (though I do not confine myself to such apparatus)
in cylindrical iron vessels, similar to what are known as Weldon Oxidizers," but
differing therefrom in this, that whereas Weldon Oxidizers are open at the top,
the vessels in which the first of the said two operations is to be performed must be
closed at the top, except that each such vessel must communicate with a pipe or
pipes for conveying away gases therefrom.
It is quite possible to perform the first operation of the process constituting the
present invention in a single vessel such as I have just indicated; but I believe that
it will usually be better, in order that a maximum proportion of the carbonic acid gas
employed may be absorbed, and that the sulphuretted hydrogen obtained may be
mixed with a minimum proportion of other gases, to employ a series of such vessels,
conducting the gases which pass off from the first vessel of the series to the bottom
of the second vessel of the series; and so on.
When thus employing a series of vessels for the first operation of the process
which constitutes the present invention, the vessels employed need not be so tall
as when only a single vessel is used for that operation, and the arrangements should
preferably be such that one vessel shall always be isolated for discharging and
recharging. Thus supposing a series of four vessels, A, B, C, and D, to be employed,
A, B, and C should be at work while D is being discharged and recharged, the
carbonic acid gas, or mixture of carbonic acid gas and other gases, being injected
into A, the gases which pass off from A being conducted to the bottom of B, those
which pass off from B being conducted to the bottom of C, and those which pass
off from C being conducted to the apparatus in which is performed the second
operation of the process. When the charge in A has been sufficiently decomposed,
A will be isolated for discharging and recharging, the carbonic acid gas, or mixture
of carbonic acid gas and other gases, now being injected into B, the gases which
pass off from B being conducted to the bottom of C, those which pass off from C
Leing conducted to the bottom of D, and those which pass off from D being
conducted to the apparatus in which the second operation is performed.
vessels at work will thus be successively A, B, and C, then B, C, and D, then C, D,
and A, then D, A, and B, then A, B, C again; and so on continually.
:
The
In the second of the two operations which collectively constitute the present
invention, sulpburetted hydrogen or a mixture of sulphuretted hydrogen and other
gases obtained as above described, is mixed (unless a sufficient quantity of free

page_text: oxygen be already present in the mixture of gases containing the sulphuretted
hydrogen) with air in the proportions above indicated, accordingly as it is desired
to obtain a maximum proportion of the sulphur of the said sulphuretted hydrogen
in the free state, or a smaller proportion of its sulphur in the free state and the
remainder thereof either as sulphurous acid or as sulphuretted hydrogen, for
application to whatever purpose, and the resulting mixture of gases is then passed
into a vessel or kiln containing a bed or layer of powder or fragments or pieces of
any not too readily fusible solid substance, or mixture of two or more such
substances, and is caused to pass through such bed or layer thereof. In thus passing
through the said bed or layer of powder or fragments or pieces of solid material
the oxygen of the mixture of gases combines with either a part of the hydrogen of
the sulphuretted hydrogen contained in that mixture of gases, or with the whole
of the hydrogen of the said sulphuretted hydrogen, or with the whole of its
hydrogen and also with a part of its sulphur, according to the proportion of free
oxygen contained in the mixture of gases employed. The vessel or kiln containing
the said bed or layer of solid material or mixture of solid materials must be
completely closed, except that it must communicate with a pipe or pipes by
means of which the mixture of gases containing sulphuretted hydrogen and free
oxygen may be fed into it, and with a pipe or pipes for conveying away the
mixture of gases and vapours passing off from it. The said vessel or kiln may
conveniently (though I do not confine myself to that form of apparatus) be an iron
box lined with brick or fire-clay, or merely a brick chamber not clothed exteriorly
with iron, and it should preferably be furnished with a false bottom pierced with
holes, or with a grid, or analogous appliance, upon which the bed or layer of powder
or fragments or pieces of solid material may be spread. The mixture of gases
containing sulphuretted hydrogen and free oxygen may be fed into the kiln either
above the said bed or below it, the mixture of gases and vapours resulting from the
reactions which take place in the interstices of the material, of which the said bed
is composed passing out of the kiln in the opposite direction.
The bed or layer of solid material or mixture of solid materials contained in the
said vessel or kiln may consist of any not readily fusible solid substance. The
more porous the material of which the bed is formed the better, and the smaller
the fragments of which it is composed also the better, provided only that such
fragments be not too small to permit of the mixture of gases passing sufficiently
freely through the bed or layer of them. In my experimental operations I have
obtained good results when using the material or mixture of materials forming the
said bed in the state of powder, and also when using it in lumps or pieces of very
various sizes. The depth of bed which I have employed has varied from a few
inches to several feet, and in practice it may vary according to the state of division
of the material or mixture of materials of which it is composed, and also according
to the rate at which the mixture of gases is fed into the kiln containing it. Except
in the case which will be mentioned below, the bed must always be heated up, by
any convenient means, before the mixture of gases is first admitted into the kiln
containing the said bed; but the heat of the reaction taking place in the
interstices between the fragments or pieces of solid material or of mixture of solid
materials of which it is composed will afterwards maintain its temperature
sufficiently, if the operation be conducted continuously, if the mixture of gases
upon which it is performed be not too poor in sulphuretted hydrogen and free
oxygen, and if the rate at which the mixture of gases is fed into the kiln be not
too slow. In other cases it will be necessary to supplement the heat of the reaction
in question either by heat from some other source, applied to the bed or layer of
powder or fragments or pieces of solid material or mixture of solid materials either
externally or otherwise as may be most convenient in each case.
Among the almost innumerable substances of any one of which, or of a mixture
of any two or more of which, the bed in question may be formed, I would indicate,
as perhaps the cheapest and most convenient (though I do not confine myself to

page_text: these substances) fragments of brick, oxide of iron, oxide of manganese, asbestos
(coated or impregnated or not with a metal, an oxide, or a salt) alumina, oxide of
zinc, carbonate of zinc, lime, and calcium carbonate.
When the bed contained in the aforesaid kiln is composed either wholly or in
part of hydrated oxide of iron, hydrated oxide of manganese, or analogous
substance, it need not be beated up before commencing to pass into the kiln the
mixture of gases containing sulphuretted hydrogen and free oxygen. Such hydrated
oxides can start the required reaction or reactions at ordinary temperatures, and
though the heat developed by that reaction or those reactions soon renders the said
hydrated oxides anhydrous or nearly so, it at the same time heats the bed which at
first consisted wholly or in part of such hydrated oxide or oxides to such
temperature that, if the conditions otherwise be as above indicated, it can henceforth
maintain such reaction or reactions, notwithstanding that the said oxide or oxides
have become nearly or completely dehydrated.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Carl Friedrich Claus in the Patent Office on the 30th June 1884.
CARL FRIEDRICH CLAUS, of Mark Lane, in the City of Loudon, Chemist,
'IMPROVEMENTS IN OBTAINING FROM ALKALI-WASTE EITHER FREE SULPHUR, OR
FREE SULPHUR AND SULPHUROUS ACID, OR FREE SULPHUR AND SULPHURETTED
HYDROGEN
"
This invention consists in a method of obtaining from the residual product of the
manufacture of soda by the Leblanc process, without the use of hydrochloric acid,
either free sulphur, or free sulphur and more or less sulphurous acid, or free sulphur
and more or less sulphuretted hydrogen.
The said residual product commonly known as " alkali-waste" consists essentially
of calcium sulphide, and the first of the two operations which collectively constitute
the present invention consists in mixing the said residual product with water,
charging the mixture into closed vessels and injecting thereinto carbonic acid gas,
mixed or unmixed with other gases, whereby the calcium sulphide of the said
residual product is converted into calcium carbonate, and its sulphur is driven off
as sulphuretted hydrogen. If pure carbonic acid gas be used in this operation, the
operation may be so conducted that the resulting sulphuretted hydrogen shall be
free, or nearly free, from admixture with other gases; but it will frequently be
more convenient to use, in this operation, the gases from lime-kilns or products of
combustion, in which case the sulphuretted hydrogen obtained will be diluted by
other gases.
The second of the said two operations consists in adding to the sulphuretted
hydrogen, or mixture of sulphuretted hydrogen and other gases obtained as
aforesaid, such quantity of air that there shall then be present with the resulting
mixture of gases either just the quantity of free oxygen, or something more or
something less than the quantity of free oxygen, necessary to burn the hydrogen of
the sulphuretted hydrogen, according to the reaction :-
H, S + OH₂ O + S,
and in then passing the mixture of gases, now containing sulphuretted hydrogen
and free oxygen in the said proportions, through a bed or layer of pieces of
fragments or powder of solid material maintained at a suitable temperature either
by the heat of the resulting reaction of the oxygen of the said mixture of gases
upon either more or less of the hydrogen only, or upon the hydrogen and also more
or less of the sulphur of the sulphuretted hydrogen of that mixture of gases, or by
heat from other sources, or partly by the one and partly by the other, as will be
explained below. The result is, according to the proportion of air used, that either
the whole of the sulphur of the sulphuretted bydrogen is set free, or that part of it
is set free, the remainder of the sulphuretted hydrogen either passing off in the free
state, or being burned into sulphurous acid and vapour of water, as may be
preferred in each case.
The first of the two operations which collectively constitute the present
invention may conveniently be performed (though I do not confine myself to such
apparatus) in cylindrical iron vessels similar to what are known as "Weldon
oxidizers," but differing therefrom in this, that whereas Weldon oxidizers are open
at the top, the vessels in which the first of the said two operations is to be per-
formed must be closed at the top, but each such vessel must communicate with a
pipe or pipes for conveying away gases therefrom.
It is quite possible to perform the first operation of the process constituting the
present invention in a single vessel such as I have just indicated; but it will
J.

page_text: usually be preferable (in order that a maximum proportion of the carbonic acid gas
employed may be absorbed, and that the sulphuretted hydrogen obtained may be
mixed with a minimum proportion of other gases) to employ a series of such
vessels, conducting the gases which pass off from the first vessel of the series to the
bottom of the second vessel of the series; and so on.
When thus employing a series of vessels for the first operation of the process
which constitutes the present invention, the vessels employed need not be so tall as
when only a single vessel is used for that operation, and the arrangements should
preferably be such that one vessel shall always be isolated for discharging and
recharging. Thus, supposing a series of four vessels, A, B, C, and D to be
employed, A B and C should be at work while D is being discharged and recharged,
the carbonic acid gas or mixture of carbonic acid gas and other gases, being injected
into A, the gases which pass off from A being conducted to the bottom of B, those
which pass off from B being conducted to the bottom of C, and those which pass
off from C being conducted to the apparatus in which is performed the second
operation of the process. When the charge in A bas been sufficiently decomposed,
A will be isolated for discharging and recharging, the carbonic acid gas, or mixture
of carbonic acid gas and other gases, now being injected into B, the gases which
pass off from B being conducted to the bottom of C, those which pass off from C
being conducted to the bottom of D, and those which pass off from D being
conducted to the apparatus in which the second operation is performed, The
vessels at work will thus be successively A, B and C, then B, C, and D, then C, D,
and A, then D, A, and B, then A, B, C again; and so on continuously.
In the second of the two operations which collectively constitute the present
invention, sulphuretted hydrogen, or a mixture of sulphuretted hydrogen and other
gases obtained as above described, is mixed (unless a sufficient quantity of free
oxygen be already present in the mixture of gases containing the sulphuretted
hydrogen) with air in the proportions above indicated, according to whether it is
desired to obtain a maximum proportion of the sulphur of the said sulphuretted
hydrogen in the free state, or a smaller proportion of its sulphur in the free state
and the remainder thereof either as sulphurous acid or as sulphuretted hydrogen,
for application to any purpose; the resulting mixture of gases is then passed into
a vessel or kiln containing a bed or layer of powder or fragments or pieces of any
not too readily fusible solid substance, or mixture of two or more such substances,
and is caused to pass through such bed or layer. In thus passing through the said
bed or layer of powder or fragments or pieces of solid material, the oxygen of the
mixture of gases combines with either a part of the hydrogen of the sulphuretted
hydrogen contained in that mixture of gases, or with the whole of the hydrogen
of the said sulphuretted hydrogen, or with the whole of its hydrogen and also with
a part of its sulphur, according to the proportion of free oxygen contained in the
mixture of gases employed. The vessel or kiln containing the said bed or layer of
solid material or mixture of solid materials must be completely closed, except that
it must communicate with a pipe or pipes by means of which the mixture of gases
containing sulphuretted hydrogen and free oxygen may be fed into it, and with a
pipe or pipes for conveying away the mixture of gases and vapours passing off
from it. The said vessel or kiln may conveniently (though I do not contine myself
to such apparatus) be an iron box lined with brick or fire-clay, or merely a brick
chamber not clothed exteriorly with iron, and it should preferably be furnished
with a false-bottom pierced with holes, or with a grid, or analogous appliance, upon
which the bed or layer of powder or fragments or pieces of solid material may be
spread. The mixture of gases containing sulphuretted hydrogen and free oxygen
may be fed into the kiln either above the said bed or below it, the mixture of gases
and vapours resulting from the reactions which take place in the interstices of the
material of which the said bed is composed passing out of the kiln in the opposite
direction.
The bed or layer of solid material or mixture of solid materials contained in the
said vessel or kiln may consist of any not readily fusible solid substance. The

page_text: more porous the material of which the bed is formed the better, and the smaller
the fragments of which it is composed also the better, provided only that such
fragments be not too small to permit of the mixture of gases passing sufficiently
freely through the bed or layer of them. In my experimental operations, I have
obtained good results when using the material or mixture of materials forming the
said bed in the state of powder, and also when using it in lumps or pieces of very
various sizes. The depth of bed which I have employed has varied from a few inches
to several feet, and in practice it may vary according to the state of division of the
material or mixture of materials of which it is composed, and also according to
the rate at which the mixture of gases is fed into the kiln containing it. Except
in the case which will be mentioned below, the bed must always be heated up, by
any convenient means, before the mixture of gases is first admitted into the kiln
containing the said bed; but the heat of the reaction taking place in the interstices
between the fragments or pieces of solid material or of mixture of solid materials
of which it is composed will afterwards maintain its temperature sufficiently, if the
operation be conducted continuously, if the mixture of gases upon which it is
performed be not too poor in sulphuretted hydrogen and free oxygen, and if the
In other
rate at which the mixture of gases is fed into the kiln be not too slow.
cases it will be necessary to supplement the heat of the reaction in question either
by heat from some other source, applied to the bed or layer of powder or fragments
or pieces of solid material or mixture of solid materials either externally or other-
wise as may be most convenient in each case, or by heating the air, or the gases
containing the sulphuretted hydrogen, or both, or by admitting combustible gas,
such as carbonic oxide, together with the sulphuretted hydrogen and air.
Among the almost innumerable substances of any one of which, or of a mixture
of any two or more of which, the bed in question may be formed, I would indicate,
as perhaps the cheapest and most convenient (though I do not confine myself to
these substances) fragments of brick, oxide of iron, oxide of manganese, asbestos
(coated or impregnated or not with a metal, an oxide or a salt) alumina, oxide of
zinc, carbonate of zinc, lime, and calcium carbonate.
Such
When the bed contained in the aforesaid kiln is composed either wholly or in
part of hydrated oxide of iron, hydrated oxide of manganese, or analogous
substance, it need not be heated up before commencing to pass into the kiln the
mixture of gases containing sulphuretted hydrogen and free oxygen.
hydrated oxides can start the required reaction or reactions at ordinary tem-
peratures, and though the heat developed by that reaction or those reactions soon
renders the said hydrated oxides anhydrous or nearly so, it at the same time heats
the bed which at first consisted wholly or in part of such hydrated oxide or oxides
to such temperature that, if the conditions otherwise be as above indicated, it can
benceforth maintain such reaction or reactions, notwithstanding that the said oxide
or oxides have become nearly or completely dehydrated.
Having thus fully described my said invention and the manner of performing
the same I wish it understood that I do not claim the herein before described
method of obtaining the sulphur of alkali waste as sulphuretted bydrogen,
otherwise than in combination with the herein before described method of treating
that sulphuretted hydrogen for the obtainment of sulphur therefrom, but that what I
regard as constituting the invention to be secured to me by the herein before in part
recited Letters Patent is the combination, for the purpose of obtaining sulphur from
alkali-waste, of the method of liberating the sulphur of alkali-waste as sulphuretted
hydrogen which consists in treating alkali-waste in presence of water by carbonic
acid gas, such carbonic acid gas being mixed or not with other gases, with the
method of treating the resulting sulphuretted hydrogen or mixture of sulphuretted
bydrogen and other gases which consists in adding to that sulphuretted hydrogen,
or mixture of sulphuretted hydrogen and other gases, air in the proportions
5 indicated in the foregoing specification (unless a sufficient quantity of free oxygen
be already present therewith), and then passing the resulting mixture of gases through
a bed or layer of fragments of suitable solid material, maintained at a suitable

page_text: temperature, either by the heat of the reaction which takes place as the mixture
of gases passes through the said bed or layer of fragments of solid material, or by
heat from any other source applied thereto in any convenient way, in such-wise as
to effect the combustion of either the whole or part of the hydrogen of the said
sulphuretted bydrogen, either the whole of its sulphur being so set free, or a part
of its sulphur being so set free, and the remainder passing off either as sulphuretted
hydrogen or as sulphurous acid gas, as may be preferred in each particular case,
substantially by the means and in the manner which are above described.
In witness whereof I the said Carl Friedrich Claus have hereunto set my hand
and seal this Twenty eighth day of June in the year of our Lord One thousand
eight hundred and eighty four.
CARL FRIEDRICH CLAUS (L.S.)