IMPROVEMENTS IN EFFECTING THE RECOVERY OF SULPHUR FROM SODA WASTE
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I, WILLIAM LLOYD WISE, of No 46 Lincoln's Inn Fields, in the County of
Middlesex, Consulting Engineer and Patent Agent, do hereby declare the nature
of said invention for "IMPROVEMENTS IN EFFECTING THE RECOVERY OF SULPHUR
FROM SODA WASTE" (a communication to me from abroad by Hubert Grouven, of
Dresden, Kingdom of Saxony, Empire of Germany, Doctor of Philosophy) to be as
follows:-
This Invention relates to an improved method of recovering sulphur from soda
waste. Numerous methods have been described and patented with reference to
regaining the sulphur contained in soda waste yet none have hitherto solved the
chief practical difficulty of the question, that is to say, the treatment of these
valuable residual products without the expenditure of too much labour or too much
capital. These methods are mostly based upon the principle of converting the
insoluble sulphide of calcium into soluble combinations by oxidising it with oxygen
obtained from the air that is to say upon the conversion of the insoluble sulphide
of calcium contained in the said residual products into soluble combinations by
ineans of an oxidation effected by the oxygen contained in the atmosphere,
lixiviating the oxidised mass and precipitating the sulphur by means of hydro-
chloric acid.
According to this invention the soda waste either new or old is placed in a
kneading machine and then about 10 per cent of its weight of ordinary sawdust
carefully added. Where sawdust is mentioned it is to be understood that the
expression is intended to include the use in lieu of sawdust of waste coal of every
description, peat, moss, residuums of straw, hemp tan and such like substances.
According as the soda waste is of recent or old date from 10 to 25 per cent of hot
water is poured upon the mass. After a suitable period of time has elapsed this
mass is removed from the kneading machine in the form of a homogenous stiff and
unctuous paste which when the addition of water has been properly regulated can
be easily formed by means of a drain pipe machine into tubes of small calibre,
Irine A1

page_text: have a volume of 90 litres. 2ndly The prepared tubes
water, carbon, carbonic acid, sulphur and saw-dust about
crumbling to dust or apparently decreasing in volume.
heated by steam lose in
of their weight without
This porosity is absolutely necessary for the success of this steam process, as
according to my foreign correspondent's experiments soda waste reduced to the size
of a nut are only partially and superficially desulphurized.
The steam necessary to decompose the sulphide of calcium does not penetrate to
the centre of such pieces.
Heat is an important factor in the above process. Each of the chemical decom-
positions above described commence at a dark red heat but proceed only slowly at
such a heat.
As the temperature increases sulphuretted hydrogen is evolved and
the operation henceforth proceeds. rapidly.
With a suitable heat the process of desulphuration terminates after a lapse of
three hours. The material which is then withdrawn from the retorts presents the
form of a granular and soft mass of yellowish colour, it is moreover a pure mineral
ash in no portions of which are traces of carbon discernable. Observed with a
magnifying glass each granular piece represents a network of small tubes.
When boiled with diluted hydrochloric acid the ash evolves neither carbonic
acid, sulphuretted hydrogen nor sulphurous acids and when fused with potash and
nitre they yield only from 1 to 2 per cent of sulphuric acid which was already
contained in it in the form of sulphate of lime.
This is the best proof of the complete removal of the sulphur.
The residuum of 40 per cent of ash contains from 85 to 90 per cent of caustic
lime. Such a residuum cannot therefore be considered merely a waste product
as it is highly suitable for mortar making purposes or as manure for agricultural
purposes.
When-the sulphur has been completely removed from the soda-waste and all the
sulphur combined in the form of sulphuretted hydrogen gas, the main object of the
process is attained, as the conversion of this gas into sulphur is but a comparatively
easy matter for which several known methods may be employed.
The method invented by Dumas, based upon the following equation 2. H. S. +
S. O, 3 S+ 2 H. O is the one I prefer.
This equation is carried out by burning with a free access of air a third of the
volume of the sulphuretted hydrogen obtained from the retorts in order to produce
sulphurous acid. With the gases obtained in this process half of which consist of
hydrogen which burns easily, this combustion can be easily effected.
The sulphurous acid thus formed and the sulphuretted hydrogen are caused to
act upon one another by bringing them in contact with 10 per cent of the waste
products of salt mines otherwise termed crude carnallite. This carnallite has been
found more suitable than the chloride of calcium proposed for the purpose.
D
1

page_text: I, WILLIAM LLOYD WISE, of No 46 Lincoln's Inn Fields, in the County of
Middlesex, Consulting Engineer and Patent Agent, do hereby declare the nature
of said invention for "IMPROVEMENTS IN EFFECTING THE RECOVERY OF
SULPHUR FROM SODA-WASTE" (a communication to me from abroad by Hubert
Grouven, of Dresden, Kingdom of Saxony, Empire of Germany, Doctor of
Philosophy), and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
This Invention relates to an improved method of recovering sulphur from soda
waste. Numerous methods have been described and patented with reference to
regaining the sulphur contained in soda-waste yet none have hitherto solved the
chief practical difficulty of the question, that is to say, the treatment of these
valuable residual products without the expenditure of too much labour or too
much capital. These methods are mostly based upon the principle of converting
the insoluble sulphide of calcium into soluble combinations by oxidising it with
oxygen obtained from the air that is to say upon the conversion of the insoluble
sulphide of calcium contained in the said residual products into soluble combinations
by means of an oxidation effected by the oxygen contained in the atmosphere
lixiviating the oxidised mass and precipitating the sulphur by means of
hydrochloric acid.
According to this invention the soda waste either new or old is placed in a
kneading machine and then about 10 per cent of its weight of ordinary sawdust
regularly added. Where sawdust is mentioned it is to be understood that the
expression is intended to include the use in lieu of sawdust of waste coal of every
description, peat, moss, residuums of straw hemp tan and such like substances.
According as the soda waste is of recent or old date from 10 to 25 per cent of hot
water is poured upon the mass. After a suitable period of time has elapsed this
mass is removed from the kneading machine in the form of a homogeneous stiff
and unctuous paste which when the addition of water has been properly regulated
can be easily formed by means of a drain pipe machine into tubes of small calibre.
These tubes should preferably have a length of about 250 /m an outer diameter
of, 45/ and an inner diameter of 20 / so that the thickness of their walls
should not exceed from 12 to 13 / as a greater thickness is not advisable.
These tubes are placed upon boards or shelves at the rate of about twenty pieces
on each shelf the said boards or shelves being secured in frames arranged in a shed
to which the air is allowed free access and are left to be acted upon by the oxygen
of the air. This oxidation which takes place throughout the tubes rapidly hardens
them. They were when first laid out on the shelves of a somewhat soft consistence.
After two days they become brittle so that, they can be easily broken into several
pieces without any portion of them falling to powder.
After they have been thus broken into pieces, they form a highly porous material
which by reason of its porosity is not much reduced in weight when ignited
according to the following process.
The retort furnace employed in carrying this process into practice may be of any
suitable construction provided it can be heated to a high temperature and through
which steam can be passed.

page_text: In order to clearly explain the theory of the process, the results of three analyses
of soda-waste are appended.
8.
Soda Waste
6 Months old
1
Soda Waste
Fresh
2.
Soda Waste
Fresh
-
Water (dried at 110°)
25.8%
27.0%
19.4%
chloric acid and then ignited with
oxide of copper, according to a well-
known analytical process
Total amount of sulphur (obtained by } 16.0%
fusion with nitre and potash)
Carbon, extracted with diluted hydro-
15.4%
18.0%
8.1.%
5.7 %
10.0%
"
Ashes. Freed from sulphur by com-
bustion through steam only
-} 39.5%
39.7 %
42.8%
It may be assumed as a general rule that 100 kilos of soda-waste contain 8 kilos
of carbon in the form of coke-dust which together with 4 kilos of carbon contained
in 10 kilos of sawdust added to the above soda-waste amounts to 12 kilos of carbon
which are converted into gas by means of steam. 18 kilos of water in the form
of steam at a high temperature will be required to convert the above 12 kilos of
carbon into gas The high temperature employed will exclude the production of
carbonic acid. The steam will have produced at the end of a couple of hours
sufficient carbonic oxide and hydrogen to thoroughly reduce all the sulphur
compounds such as thionic acid, hypo-sulphurous acid, tetrathionic acid, sulphurous
acid, dithionic acid, and sulphuric acid, nearly all the sulphur being converted into
the form of sulphide of calcium.
The latter is decomposed at a moderately high temperature by means of super-
heated steam, into sulphuretted hydrogen and oxide of calcium.
The sulphide of iron (several per cent of which is always present in the above
products) is even more rapidly decomposed by steam than the sulphide of calcium
and becomes decomposed into sulphuretted hydrogen and black oxide of iron.
The bi-sulphide of calcium which is also generally present in a small quantity in
the above products is decomposed into sulphur vapour and sulphide of calcium.
It has been found advantageous to introduce the steam into the retorts imme-
diately after the latter are filled and for the purpose of obtaining a constant excess
of steam, 35 to 40 kilos are employed per 100 kilos of soda-waste.
The addition of saw-dust acts usefully by increasing the proportion of carbon;
its chief action however is to greatly increase the porosity of the material.
The two following statements will more fully illustrate this action;-1tly 10 kilos
of sawdust have a volume of about 70 litres whereas 100 kilos of soda-waste have
a volume of 90 litres. 2ndly The prepared tubes heated by steam lose in water,
carbon, carbonic acid, sulphur and sawdust about of their weight without
crumbling to dust or apparently decreasing in volume.
This porosity is absolutely necessary for the success of this process, as according
to my foreign correspondent's experiments soda-waste even reduced to the size of
nuts is only partially and superficially desulphurized.
The steam necessary to decompose the sulphide of calcium does not penetrate to
the centre of such pieces.
Heat is an important factor in the above process.
Each of the chemical decompositions above described commences at a dark red
heat but proceeds only slowly at such a heat. As the temperature increases, the
development of sulphuretted hydrogen increases and the operation henceforth
proceeds rapidly.
With a suitable heat the process of desulphuration terminates after a lapse of
three hours.
The material which is then withdrawn from the retorts presents the form of a
granular and soft mass of yellowish colour, it is moreover a pure mineral ash in no

page_text: portions of which are traces of carbon discernable. Observed with a magnifying
glass each granular piece represents a net work of small tubes.
When boiled with diluted hydrochloric acid the ash evolves neither carbonic
acid nor sulphuretted hydrogen nor sulphurous acid and when fused with potash
and nitre they yield only from 1 to 2 per cent of sulphuric acid which was already
contained in it in the form of sulphate of lime. This is the best proof of the
complete removal of the sulphur.
The residuum of 40 per cent of ash contains from 85 to 90 per cent of caustic
lime; Such a residuum cannot therefore be considered merely a waste product as
it is bighly suitable for mortar making purposes or. as manure for agricultural
purposes.
When the sulphur has been completely removed from the soda-waste, and all
the sulphur combined, in the form of sulphuretted hydrogen gas, the main object
of the process is attained, as the conversion of this gas into sulphur is but a
comparatively easy matter for which several known methods may be employed..
The method invented by Dumas, based upon the following equation
2. H. S. + S. O₂. 3. S. 2 H. O. is the one I prefer.
=
--
This equation is carried out by burning with a free access of air a third of the
volume of the sulphuretted hydrogen obtained from the retorts in order to produce
sulphurous acid. With the gases obtained in this process half of which consist of
hydrogen which burns easily, this combustion can be easily effected.
The sulphurous acid thus formed and the sulphuretted hydrogen are caused to
act upon one another by bringing them in contact with 10 per cent of the waste
products of salt mines otherwise termed crude carnallite.
This carnallite has been found more suitable than the chloloride of calcium
proposed for the purpose.
Having now particularly described and ascertained the nature of said invention,
and in what manner the same is to be performed, I declare that what I claim is
In effecting the recovery of sulphur from soda waste:
1 The production of a homogeneous mass of the consistency of stiff paste by
intimately mixing in a suitable kneading or mixing machine, fresh or old soda
waste (a) with about 10 per cent of ordinary sawdust and from 10 to 20 per cent
of water, or (b) with water and a substance or substances the action of which is
chemically and physically similar to that of sawdust, such as waste coal, peat,
moss, residuums of straw, hemp, tan, and the like; substantially as described.
2 Converting a mass such as referred to in Claim 1 into tubes of small calibres
by means of a press and exposing these tubes to the air in such manner as to make
them firm, brittle, and easily breakable into pieces substantially as described.
3 Converting into sulphuretted bydrogen the sulphides and sulphur oxides
contained in a porous mass of pieces such as referred to in Claim 2, by placing the
said mass of pieces in a retort, intensely heating the same and causing the mass to
be acted on by super-heated steam substantially as described.
4 The hereinabove described process of recovering sulphur from soda-waste by
kneading either fresh or old soda-waste with sawdust or allied or analogous
carbonaceous substances, and water into a homogeneous mass, converting this mass
into tubes, air drying them till they are hard and brittle, breaking them up and
heating the lumps in a retort to a high temperature and passing superheated steam
into it so that the combined sulphur is converted into sulphuretted hydrogen from
which the sulphur can be obtained as set forth above.