IMPROVEMENTS RELATING TO THE RECOVERY OF SULPHUR FROM ALKALI WASTE AND TO THE APPLIANCES AND DISPOSITIONS TO BE USED FOR THAT PURPOSE
Year: 1882

page_text: LETTERS PATENT to Walter Weldon, of Rede Hall, Burstow, in the County
of Surrey, for an Invention of IMPROVEMENTS RELATING TO THE RECOVERY
OF SULPHUR FROM ALKALI WASTE AND TO THE APPLIANCES AND DISPOSITIONS
TO BE USED FOR THAT PURPOSE Communicated to him from abroad by
D Max Schaffner and Wilhelm Helbig, both of Aussig, in the Empire of
Austria,
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the
Office of the Commissioners of Patents on the 6th July 1882.
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey, IMPROVE-
MENTS RELATING TO THE RECOVERY OF SULPHUR FROM ALKALI WASTE AND TO
THE APPLIANCES AND DISPOSITIONS TO BE USED FOR THAT PURPOSE, a communi-
cation from Dr Max Schaffner and Wilhelm Helbig, both of Aussig, in the Empire
of Austria,
The present invention consists in certain improvements upon a former invention
for which the Letters Patent numbered 955 of the year 1878 have been granted.
The said former invention relates to the separation from alkali waste of sulphur
in the state of sulphuretted hydrogen, which sulphuretted hydrogen is then either
wholly burnt into sulphurous acid, or treated for the obtainment of free sulphur
from it by burning a part only of the sulphuretted hydrogen into sulphurous acid,
and causing the sulphurous acid so obtained to react upon the other part of
the sulphuretted hydrogen in presence of a solution of a metallic chloride or
other salt.
The improvements constituting the present invention are as follows:
First. The combustion of sulphuretted hydrogen has been found to be accom-
panied by the production of an appreciable proportion of sulphuric acid, the whole
of the sulphur of which is lost when the whole of the products of the combustion
of sulphuretted bydrogen are mixed with free sulphuretted hydrogen in contact
with a solution of a metallic chloride. To avoid losing this sulphuric acid, and
at the same time to avoid the inconveniences which are occasioned by its reaction
upon the metallic chloride, by the present invention the products of the combustion

page_text: of that portion of the sulphuretted hydrogen treated which is burnt to give
sulphurous acid to react upon the other portion of the sulphuretted hydrogen are
passed through a condensing apparatus in which they are deprived of some or all
of their sulphuric acid before being brought into contact with the other portion
of the sulphuretted hydrogen in presence of a solution of a metallic chloride. The
said condensing apparatus may be a tower packed with coke or flints or other
material down which either water or weak sulphuric acid is kept trickling. The
condensing apparatus may thus serve also as a cooler, to bring down the tem-
perature of the sulphurous acid to the degree to which it ought to be cooled before
entering the apparatus in which it is to react on sulphuretted hydrogen.
Second. When the sulphur of alkali waste is driven off by means of hydro-
chloric acid, the resulting sulphuretted hydrogen is contaminated by carbonic acid
gas, which interferes with its combustion, and is prejudicial in other ways. By
the present invention, before burning the said sulphuretted hydrogen, it is treated
for the separation of carbonic acid from it. This is effected by bringing the
mixture of sulphurous acid and carbonic acid gases into intimate contact with
either milk of lime or a solution of sulphide of calcium, or with a solution of
baryta or of barium sulphide, or with either of these bodies in the solid state.
Third. When alkali-waste has been heated with solution of magnesium chloride
and as much as possible of its sulphur has been thereby driven off as sulphuretted
hydrogen, there remains in the apparatus in which the operation has been per-
formed a solution of chloride of calcium holding magnesia and other matters in
suspension, and holding some sulphuretted hydrogen in solution. Under the
present invention, to prevent this dissolved sulphuretted hydrogen being given off
into the atmosphere during the transference of the said residue into the apparatus
in which the next operation of the process is to be performed, neither apparatus
is allowed to communicate with the atmosphere during such transference. The
"Decomposer," or apparatus in which the alkali-waste is heated with solution of
chloride of magnesium, is of course a closed vessel, from which the sulphuretted
hydrogen disengaged in it is conveyed by a suitable pipe to the apparatus in which
it is treated for the utilization of its sulphur. This pipe should be closed by a
valve during the discharge of the decomposer, another valve or cock being at the
same time opened for the admission of air into the Decomposer. The contents of
the Decomposer should then be drawn off into another closed vessel, which may
conveniently be the Converter, or the apparatus in which the next operation of
the process is performed, a valve first being opened for the escape from this vessel
of the air displaced by the admission into it of the contents of the Decomposer.
The air thus displaced from the Converter, and also, during the first portion of the
subsequent injection of carbonic acid into the Converter, the mixture of gases
passing off therefrom, should either go direct to a furnace or to a chimney, or be
passed through water holding oxide of iron in suspension, or holding either in
suspension or in solution any other body suitable for absorbing and retaining the
sulphur of sulphuretted hydrogen.
Fourth. By the present invention a filter or screen, preferably contained in a
closed vessel, may be placed between the Decomposer and the Converter, in such
wise that the contents of the Decomposer shall pass through this filter or screen
before reaching the Converter.
Fifth. By the present invention, instead of performing the reaction of sul-
phuretted hydrogen upon sulphurous acid in presence merely of a solution of
a metallic chloride, the two gases are made to react on each other in presence of, a
mixed solution of a metallic chloride and free hydrochloric acid.
Sixth. By the present invention, when the alkali-waste is decomposed, not by
solution of magnesium chloride, but by free hydrochloric acid, the waste and the
acid are treated together in Decomposers more or less like Weldon chlorine stills,
built of stone, clamped with iron, and provided with pipes of either stone earthern-
ware, ebonite, or other material sufficiently inattackable by hydrochloric acid, by
means of which steam may be injected into them. These steam-pipes may enter

page_text: either through the sides or through the top of the said Decomposers. They should
preferably descend not quite to the bottom of the Decomposers, though this is not
essential. The Decomposers may be furnished with hoppers, each hopper being.
provided with a mechanical appliance permitting waste to be fed into the
Decomposers without sulphuretted bydrogen escaping from them. Several modes
of proceeding may be followed. By one mode, acid may be run into the
Decomposers first, and then waste added gradually until the acid is completely
neutralized by a slight but sufficient excess of waste. The contents of the
Decomposer should then be allowed to settle in the Decomposer itself, after
which the supernatant solution should be run off by a cock placed sufficiently
above the bottom of the Decomposer to permit of the clear solution running off
leaving the deposit undisturbed. When the clear solution has been run off, tho
Decomposer will be ready for the commencement of the next operation. By
another mode, the Decomposer may be charged first with waste, the acid being
run in afterwards. Or both acid and waste may enter the Decomposer simul-
taneously. Whatever mode of working be followed up to nearly the end of the
operation, however, at the end of it an excess of waste must be present, in order
to secure that the acid be neutralized completely, and at the end of the operation
the undissolved excess must be allowed to settle out, as aforesaid. The settling
should preferably take place in the Decomposers themselves, though separate
vessels may also be used for it. It will be well to inject steam into the Decom-
posers towards the latter part of the operation in them. In running off the
residue of the operation performed in them the same precautions should be
observed and similar dispositions should be employed as when running off
the residual product of the decomposition of waste by solution of magnesium
chloride.
Seventh. The present invention provides another method of admitting the waste
into the Decomposers, this other method being equally applicable whether the
waste be treated for the decomposition of its calcium sulphide by solution of
magnesium chloride or by hydrochloric acid. This other method consists in
grinding the waste to a mud with water or with a saline solution and then
admitting the mud so formed into the Decomposers through an opening closed
by a hydraulic lute, the mud being kept constantly agitated until it enters the
Decomposers.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Walter. Weldon in the Great Seal Patent Office on the 5th January
1883.
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey, "IMPROVE-
MENTS RELATING TO THE RECOVERY OF SULPHUR FROM ALKALI WASTE AND TO
THE APPLIANCES AND DISPOSITIONS TO BE USED FOR THAT PURPOSE," a Communi-
cation to me from Abroad from D Max Schaffner and Wilhelm Helbig, both of
Aussig, in the Empire of Austria,
The present invention consists in certain improvements upon a former, invention
for which Letters Patent numbered 955 of the year 1878 have been granted.
The said former invention relates to the separation from Alkali waste of sulphur
in the state of sulphuretted hydrogen, which sulphuretted hydrogen is then either
wholly burnt into sulphurous acid, or treated for the obtainment of free sulphur
from it by burning a part only of the sulphuretted hydrogen into sulphurous acid,
and causing the sulphurous acid so obtained to react upon the other part of the
sulphuretted hydrogen in presence of a solution of a metallic chloride or other salt.
The improvements constituting the present invention are as follows:
First. The combustion of sulphuretted hydrogen has been found to be accom-
panied by the production of an appreciable proportion of sulphuric acid, the whole
of the sulphur of which is lost when the whole of the products of the combustion
' of sulphuretted hydrogen are mixed with free sulphuretted hydrogen in contact
with a solution of a metallic chloride. To avoid losing this sulphuric acid, and at
the same time to avoid the inconveniences which are occasioned by its reaction
upon the metallic chloride, by the present invention the products of the combustion
of that portion of the sulphuretted hydrogen treated which is burnt to give
sulphurous acid to react upon the other portion of the sulphuretted hydrogen are
passed through a condensing apparatus in which they are deprived of some or all
of their sulphuric acid before being brought into contact with the other portion of
the sulphuretted hydrogen in presence of a solution of a metallic chloride. The
said condensing apparatus may be a tower packed with coke or flints or other
material down which either water or weak sulphuric acid is kept trickling. The
condensing apparatus may thus serve also as a cooler, to bring down the temperature
of the sulphurous acid to the degree to which it ought to be cooled before entering
the apparatus in which it is to react on sulphuretted. hydrogen.
Second. When the sulphur of alkali waste is driven off by means of hydrochloric
acid, the resulting sulphuretted hydrogen is contaminated by carbonic acid gas,
which interferes with its combustion, and is prejudicial in other ways. By the
present invention, before burning the said sulphuretted hydrogen, it is treated for
the separation of carbonic acid from it. This is effected by bringing the mixture
of sulphurous acid and carbonic acid gases into intimate contact with either milk
of lime or a solution of sulphide of calcium, or with a solution of baryta or of
barium sulphide, or with either of these bodies in the solid state.
Third. When alkali-waste has been heated with solution of magnesium chloride
and as much as possible of its sulphur has been thereby driven off as sulphuretted
bydrogen, there remains in the apparatus in which the operation has been
performed a solution of chloride of calcium holding magnesia and other matters in
suspension, and holding some sulphuretted bydrogen in solution. Under the
present invention, to prevent this dissolved sulphuretted hydrogen being given off
into the atmosphere during the transference of the said residue into the apparatus
in which the next operation of the process is to be performed, neither apparatus is

page_text: allowed to communicate with the atmosphere during such transference. The
"Decomposer," or apparatus in which the alkali-waste is heated with solution of
chloride of magnesium, is of course, a closed vessel, from which the sulphuretted.
bydrogen disengaged in it is conveyed by a suitable pipe to the apparatus in which
it is treated for the utilization of its sulphur. This pipe should be closed by a.
valve during the discharge of the Decomposer, another valve or cock being at the
same time opened for the admission of air into the Decomposer. The contents of
the Decomposer should then be drawn off into another closed vessel, which may
conveniently be the Converter, or the apparatus in which the next operation of the
process is performed, a valve first being opened for the escape from the vessel of
the air displaced by the admission into it of the contents of the Decomposer. The
air thus displaced from the Converter, and also, during the first portion of the
subsequent injection of carbonic acid into the Converter, the mixture of gases
passing off therefrom, should either go direct to a furnace or to a chimney, or be
passed through water holding oxide of iron in suspension, or holding either in
suspension or in solution any other body suitable for absorbing and retaining the
sulphur of sulphuretted hydrogen.
Fourth. By the present invention a filter or screen, preferably contained in a
closed vessel, may be placed between the Decomposer and the Converter, in such
wise that the contents of the Decomposer shall pass through this filter or screen
before reaching the Converter.
Fifth. By the present invention, instead of performing the reaction of
sulphuretted hydrogen upon sulphurous acid in presence merely of a solution of a
metallic chloride, the two gases are made to react on each other in presence of a
mixed solution of a metallic chloride and free hydrochloric acid.
Sixth. By the present invention, when the alkali-waste is decomposed, not by
solution of inagnesium chloride, but by free hydrochloric acid, the waste and the
acid are treated together in Decomposers more or less like Weldon chlorine stills,
built of stone, clamped with iron, and provided with pipes of either stone,
earthenware, ebonite, or other material sufficiently unattackable by hydrochloric
acid, by means of which steam may be injected into them. These steam-pipes
may enter either through the sides or through the top of the said Decomposers.
They should preferably descend not quite to the bottom of the Decomposers, though
this is not essential. The Decomposers may be furnished with hoppers, each
hopper being provided with a mechanical appliance permitting waste to be fed into
the Decomposers without sulphuretted hydrogen escaping from them. Several
modes of proceeding may be followed. By one mode, acid may be run into the
Decomposers first, and then waste added gradually until the acid is completely
neutralized by a slight but sufficient excess of waste. The contents of the
Decomposer should then be allowed to settle in the Decomposer itself, after which
the supernatant solution should be run off by a cock placed sufficiently above the
bottom of the Decomposer to permit of the clear solution running off leaving the
deposit undisturbed. When the clear solution has been run off, the Decomposer
will be ready for the commencement of the next operation. By another mode, the
Decomposer may be charged first with waste, the acid being run in afterwards.
Or both acid and waste may enter the Decomposer simultaneously. Whatever
mode of working be followed up to nearly the end of the operation, however, at
the end of it an excess of waste must be present, in order to secure that the acid be
neutralized completely, and at the end of the operation the undissolved excess must
be allowed to settle out, as aforesaid. The settling should preferably take place in
the Decomposers themselves, though separate vessels may also be used for it. It
will be well to inject steam into the Decomposers towards the latter part of the
operation in them. In running off the residue of the operation performed in them
the same precautions should be observed and similar dispositions should be
employed as when running off the residual product of the decomposition of waste
by solution of magnesium chloride.
Seventh. The present invention provides another method of admitting the waste

page_text: into the Decomposers, this other method being equally applicable whether the
waste be treated for the decomposition of its calcium sulphide by solution of
magnesium chloride or by hydrochloric acid. This other method consists in
grinding the waste to a mud with water or with a saline solution and then
admitting the mud so formed into the Decomposers through an opening closed by
a hydraulic lute, the mud being kept constantly agitated until it enters the
Decomposers.
What my correspondents claim as the invention to be secured to them by the
herein before in part recited Letters Patent is the improvements relating to the
recovery of sulphur from alkali-waste and to the appliances and dispositions and
modes of procedure to be employed for that purpose which are set forth in the
foregoing specification.
"
In witness whereof I, the said Walter Weldon, have hereunto set my band
and seal this fourth day of January in the year of Our Lord One
thousand eight hundred and eighty-three.
T&T MAD THAT DAY