IMPROVEMENTS IN TREATING SODA WASTE TO OBTAIN SULPHUR THEREFROM.” SODA WASTE TO OBTAIN SULPHUR THEREFROM
Year: 1865

page_text: LETTERS PATENT to Max Schaffner, Director of the Chemical Works
of Aussig, in Bohemia, for the Invention of "IMPROVEMENTS IN TREATING
SODA WASTE TO OBTAIN SULPHUR THEREFROM.”
SODA WASTE TO OBTAIN SULPHUR THEREFROM.”
Sealed the 13th March 1866, and dated the 23rd September 1865.
PROVISIONAL SPECIFICATION left by the said Max Schaffner at the
Office of the Commissioners of Patents, with his Petition, on the 23rd
September 1865.
I, MAX SCHAFFNER, Director of the Chemical Works of Aussig, in Bohemia,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
TREATING SODA WASTE TO OBTAIN SULPHUR THEREFROM," to be as follows:-
My Invention consists of the three following parts.
1. In a method or system of exposing the soda waste in contact with atmo-
spheric air, so that soluble polysulphurets and hyposulphites are formed in
constant proportions to each other.
2. In methods of treating the liquid obtained from soda waste so exposed
by which the polysulphurets and the byposulphites are caused to assist in
decomposing each other, from which decomposition a deposition of sulphur
results.

page_text: 3. In a method or renning the sulphur obtained and rendering it fit for the
market.
The mode of proceeding is as follows:-The soda waste is tipped into large
and high heaps, which I prefer to be from 8 to 10 feet high; in this state
I allow the soda waste to remain for about 2 months or longer; I do not con-
sider the soda waste fit for further treatment until a sample cut out of the
heap with a pickaxe shews a dark yellowish green colour, or at all events
assumes such a colour after a few hours' exposure to the air. When this
stage of decomposition has been reached the soda waste is lixiviated, and the
liquor obtained is composed principally of polysulphurets of calcium with
some hyposulphites. After the lixiviation is finished the waste is exposed to
another oxidizing process, and this is effected in pits which are somewhere
about 6 feet deep, and of considerable breadth, being sunk into the ground so
that the heat generated by the oxidation is retained effectually through the
whole mass. The waste now is no longer so compact as at the commencement,
but it is more granular, and allows the air to penetrate more easily into the
interior, hence this oxidization is finished in a few days. The waste is now
washed out again with water, and the liquor obtained is much richer than the
first in hyposulphites, and contains the polysulphurets to but a very subordinate
extent. After this second lixiviation a third oxidation in contact with air and a
third lixiviation follows, conducted in a similar way to the second, and the liquor
obtained is the richest in hyposulphites and the poorest in polysulphurets
of the three washings. All the liquors are collected in the same reservoir,
and the mixture will contain a pretty even per-centage of polysulphurets and
byposulphites.
2. The decomposition of the polysulphurets and byposulphites contained in the
lixiviated liquor is effected by means of muriatic acid employed in such a manner
that the result of the process is sulphur only. Two closed vessels connected
together by pipes are filled with sulphur liquor, and muriatic acid is added to the
liquor; in the first of these two vessels sulphuretted hydrogen will at the com-
mencement be set free, owing to the decomposition of the polysulphurets, and
later sulphurous acid is liberated, owing to the decomposition of the hyposulphites,
sulphur of course is simultaneously precipitated. Both gases are passed into the
second vessel through a pipe which reaches well down into the liquor of this
second vessel. The sulphuretted hydrogen gas occasions no alteration of the
liquor and it is allowed to escape; but the sulphurous acid decomposes the
polysulphurets in this vessel and converts them with the formation of sulphur
(which. is precipitated as a granular powder) into hyposulphates. The liquor
from the first vessel, which is composed of chloride of calcium and precipitated

page_text: sulphur, is now emptied, and this first vessel is filled again with fresh sulphur
liquor. Muriatic acid is then added to the liquor in the second vessel, and
the gases evolved are conveyed by the pipe into the sulphur liquor in the first
vessel. Much less sulphuretted hydrogen will be produced than was obtained in
the first operation just described, because the polysulphurets had been already
almost completely transformed into hyposulphites by means of the sulphurous
acid previously sent over from the first filling of the first vessel, for this reason
a much larger quantity of sulphurous acid gas will be formed, and this amount
of sulphurous acid is now quite sufficient to transform all the polysulphurets
in the first vessel entirely into hyposulphites. The second vessel is now
emptied and refilled with fresh sulphur liquor, and muriatic acid is added to
the first vessel. The product in the shape of gases is now only sulphurous
acid, which is again fully sufficient to decompose all the polysulphurets in
the liquor of the other or second vessel into byposulphites. Sulphuretted
hydrogen is thus formed only at the commencement of operations, and its forma-
tion entirely ceases afterwards for any length of time, during which the two
decomposing vessels may be kept at work uninterruptedly, because at the time
when the muriatic acid is added there are only hyposulphites left to deal with,
which with muriatic acid produce sulphurous acid simultaneously with the
formation and precipitation of sulphur. This sulphurous acid gas again decom-
poses a fresh quantity of polysulphurets in the other vessel, also with the pre-
cipitation of sulphur, and it thus prepares the liquor in this other vessel for
the decompositiou with muriatic acid.
The decomposition of the sulphur liquor by means of muriatic acid may be
also accomplished by pouring the boiling sulphur liquor into a vessel charged
with muriatic acid, when the polysulphurets and hyposulphites mutually
decompose each other, the result being sulphur, and there are no gases lost.
But this modification of the manipulation is somewhat less perfect than the
one just described.
3. The precipitated sulphur by either of the preceding operations obtained in
a granular form and mixed with impurities, such as gypsum, is melted under
water and under a pressure of 1 atmospheres, by which means it is perfectly
refined and may be cast into any of the usual salcable forms. The sulphur is
first drained of the chloride of calcium solution on a filter, and it is then
removed to a cylindrical steam boiler, and clean water is added to it in the
proportion of one of sulphur to two of water, so that it forms a fluid mass,
which is kept in constant motion by means of a stirrer. The boiler may be
heated either by direct fire or else by steam from another steam boiler. In a
short time the whole of the sulphur will be melted; it settles, and is then

page_text: allowed to run off through a cock, and can be cast into any form desired. The
small crystals of gypsum which previously had been mixed with it remain
suspended in the water, standing on the surface of the sulphur, and this water
is run out after the whole of the sulphur has been removed.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Max Schaffner in the Great Seal Patent Office on the 23rd
March 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Max
SCHAFFNER, Director of the Chemical Works of Aussig, in Bohemia, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-third day of September, in the year of our
Lord One thousand eight hundred and sixty-five, in the twenty-ninth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Max Schaffner, Her special licence that I, the said Max
Schaffner, my executors, administrators, and assigns, or such others as I, the
said Max Schaffner, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "IMPROVE-
MENTS IN TREATING SODA WASTE TO OBTAIN SULPHUR THEREPROM," upon the
condition (amongst others) that I, the said Max Schaffner, my executors
or administrators, by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Max Schaffner, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say :-
Many attempts have before been made to recover the sulphur from soda
waste, but which have not, so far as I am informed, been beneficial.

page_text: My mode of treatment, which is hereafter described, differs from all others,
and is performed in the following manner :-The soda waste is subjected to a
process of twice, or better thrice repeated exposure in contact with atmospherio
air, as hereafter explained. The products thus obtained are lixiviated with
water in such manner that a highly concentrated lye is obtained, and such lye
is then subjected to the action of muriatic acid, by which the polysulphurets
and the byposulphites are caused by mutual decomposition to deposit sulphur,
which by the process hereafter described is purified.
The mode of proceeding is as follows:-The soda waste is tipped into large
and high heaps, which it is preferred should be from 8 to 10 feet high; the
heaps should not be small. In this state the soda waste is allowed to remain
for about two months or longer, depending very much on the mechanical
condition of the soda waste and on the state of the weather, warm weather
tending to accelerate the required change. When a sample from the interior
of a heap shows a dark yellowish green color, or assumes such color after a
few hours' exposure to the air, as much of the heap as is intended to be treated
the following day is removed from the heap and thrown up in the shape of a
small conical heap, where it heats, and in about 4 hours it becomes fit for the
lixiviating process, in which process apparatus such as that now in general
use for the lixiviation of black ash is employed, but with this difference, that
the apparatus is of larger dimensions, the vats being by preference constructed
of common masonry, but other material may be employed in their construction.
The liquor obtained is composed principally of polysulphurets of calcium with
some hyposulphites. The washing process is .continued until such time as the
liquor running off shews, on testing, no perceptible trace of sulphurets. The
weak liquors are employed in the lixiviation of a fresh quantity of the pre-
pared soda waste. The strong liquor generally tests 15 to 18° Beaumé, or
1-116 to 1-141 specific gravity. After this lixiviation is finished the soda
waste is exposed to another oxidising process by exposure to the atmosphere,
and this is effected in long pits, which are sunk into the ground close to the
lixiviating apparatus. These pits are preferred to be from 4 to 6 feet deep,
8 to 10 feet wide, and from 30 to 40 feet long. The soda waste after the
first lixiviation is altered, not being so slimy and compact as it was at the
commencement, but more granular and sandy, and consequently it allows the
air to penetrate more easily into the interior; hence this second oxidation by
the atmosphere progresses much more rapidly than the first. The dark
yellowish green color is again the test by which the progress of the process
and sufficient preparation of the soda waste are judged of. The second
oxidation of the soda waste could be effected in heaps, but pits sunk into the

page_text: ground are preferred, as the heat (which is produced by the oxidation, and
which is very essential for a uniform progress of the process,) is retained more
perfectly, and the whole mass thus operated upon becomes ready at or about
the same time. The soda waste is again washed, and the liquor obtained is
much richer than the first in byposulphites, and contains the polysulphurets
to a lesser extent than the first. After this second lixiviation the soda waste
is subjected to a third similar oxidation by contact with atmospheric air in
pits, and then to a third lixiviation conducted in a similar way to the second.
The soda waste, when exposed to this third oxidation, is still less slimy than
in the second, it is more granular (or like gravel), which enables the atmo-
sphere to permeate it more freely. The liquor obtained is the richest of the
three liquors in byposalphites and the poorest in polysulphurets. It is found
desirable thus to conduct the three several oxidising and lixiviating processes,
and that there should be at all times three distinct oxidations of soda waste
and lixiviations going on simultaneously. The liquors of the three lixiviations
are collected together in a large stone cistern, from which they are pumped
as required to the decomposing process. The lye thus obtained consists of a
mixture of polysulphuret of calcium. and hyposulphite of lime, and it is
important that these two salts should be in the proportion to each other which
results from the three different processes of oxidation and lixiviation above
described.
The decomposition of the polysulphurets and hyposulphites contained in the
lixiviated liquor is effected by means of muriatic acid, which acts in the
following manner:-When muriatic acid is added to a liquor composed of
polysulphuret of calcium and hyposulphite of lime, the polysulphuret is acted
upon in the first instance and in preference to the hyposulphite, sulphur is
precipitated, and sulphuretted hydrogen is liberated, and it is only after the
whole of the polysulphuret has been decomposed that the muriatic acid begins
to net on the hyposulphite of lime. Sulphurous acid gas is evolved simul-
taneously with a precipitation of sulphur and chloride of calcium is formed,
and it should be stated that if a stream of sulphurous acid gas is introduced
into a liquor containing polysulphuret of calcium, precipitation of sulphur and
the formation of byposulphite of lime will result.
Thus, supposing that two closed vessels A and B, shown in the Diagram X,
be filled with lye from the large store cistern, if muriatic acid be then poured
into the vessel A, sulphuretted hydrogen will at the commencement be set
free, as just described, owing to the decomposition of the polysulphuret. If
the tap His shut and the tap h.open the sulphuretted bydrogen will pass over
through the piper into the liquor contained in the vessel B, and thence it

page_text: will escape through the tap h and the waste pipe p into the open air. After
the polysulphurets in the vessel A have thus been decomposed a further
addition of muriatic acid occasions the decomposition of the byposulphites;
sulphur is precipitated and sulphurous acid gas is liberated, which also flows
over through the piper into the liquor in the vessel B, where the sulphurous
acid decomposes the polysulphurets, and converts them into hyposulphites,
whilst sulphur is precipitated. The last portions of sulphurous acid gas are
driven off from the vessel A by an injection of steam. The contents of the
vessel A are now emptied, the sulphur is separated from the solution of chlo-
ride of calcium in which it was suspended by filtration, the vessel A is filled
with a fresh lye from the stone cistern. The tap h is shut, whilst the tap H
is opened on muriatic acid being added to the contents of the vessel B, which
liquor now contains but a small per-centage of polysulphurets, they having
been to a great extent transformed into hyposulphites by the sulphurous acid
previously sent over from the vessel A, and thus, when adding muriatic acid
to the liquor in the vessel B, much less sulphuretted bydrogen will be pro-
duced than was obtained in the operation just described. This small portion
of sulphuretted hydrogen passes through the pipe R into the fresh liquor in
the vessel A, and it escapes through the tap H by the pipe p into the open
air. On the other hand, when adding further quantities of muriatic acid to
the liquor in the vessel B, a by far larger amount of sulphurous acid gas, us
compared with that from the first decomposition in the vessel A, will bo
produced through the decomposition of the byposulphites. This sulphurous
acid gas will pass through the pipe R into the liquor in the vessel A, and will
be found sufficient to transform all the polysulphurets in the vessel A into
byposulphites. The contents of the vessel B are now to be emptied, the
precipitated sulphur is collected on a filter, the vessel B is to be again filled
with fresh liquor or lye from the stono cistern. Afterwards muriatic acid is
added to the liquor in the vessel A, the tap H being shut and the tap h
opened, when, besides the usual precipitation of sulphur, the liquor in the
vessel A. will produce only sulphurous acid gas, because in the preceding
operation all the polysulphurets had been converted into hyposulphites. The
sulphurous acid gas will flow from the piper into the fresh liquor in the
vessel B, and decompose the polysulphurets into hyposulphites, and any small
excess of sulphurous acid gas can escape through the pipe p. The vessel A is
now, in its turn, again to be filled with fresh liquor or lye, and the liquor in
the vessel B is in like manner to be decomposed by muriatic acid, and so on.
It will thus be evident that only at the commencement of the operations will
sulphuretted bydrogen be formed, and its formation will afterwards entirely

page_text: cease for any length of time during which the two decomposing vessels A
and B may be kept in work uninterruptedly, because there is always more
than a sufficient quantity of sulphurous acid present for the transformation of
the whole of the polysulphurets (contained in the next fresh quantity of liquor
or lye) into hyposulphites. From the above statement, aided by a description
of the apparatus employed, a workman will readily be enabled to carry out
this part of the process.
In the Drawings, Figures 1 to 7 shew the details of the apparatus employed
in carrying out the process above described. A and A¹³ are two cast-iron
bottom pans, each of which is closed by a similarly shaped cover B and B'.
The covers and bottoms are joined together by means of flanges and screws,
so that they form two closed vessels. The crown of each cover is provided
with four openings with flanges m, l, h, and o (Figure 4, Figure 5, and
Figure 7). On m and the pipes R and R¹ are screwed, which lead the
gases from one vessel to the other. The opening his furnished with an
earthenware pipe, through which the muriatic acid is introduced into the
decomposing vessels, and this earthenware pipe is protected by an outside iron
pipe against injury. The openings o, o, (Figure 4 and Figure 5)'serve to
connect the valves or taps H and H' with the respective covers; and these
valves or taps give the means alternately of escape to any excess of gases
through the pipe r. The pipes R and R' are furnished with heads, as shewn,
by means of which the pipes R, R', and r may be readily cleaned. The
descending or longer leg of the piping R, Figure 1, descends down into the
pan A, whilst the shorter leg of this pipe is screwed to the cover of A¹. This
arrangement is reversed with the pipe R, its longer or descending leg descends
into the pan A', and the shorter leg is screwed to the cover of A.
Figure 3 is a front view of the apparatus. m* is a man-hole to facilitate the
cleaning the inside of the vessels; L is the opening through which the liquor
or lye is charged into the vessels, it is closed by a plate with a bridge and
screw. After the decomposition in the vessels has taken place the precipitated
sulphur, together with the chloride of calcium liquor, is run off through the
opening O (Figures 3 and Figure 5), which is closed in the same manner as a
gas retort, clay being used as a luting or packing.
Figure 6 shews detached views of O on a larger scale than in the other
Figures. In the cover O of this opening, and near the lowest part of it, a
hole n of about 14 inches in diameter is left, which is usually closed with a
wooden plug. When the liquor and the sulphur are to be drawn off from the
vessel this wooden plug is to be removed, and most of the liquid will pass off
through this opening, after which the cover O is to be removed. On the front

page_text: part of each of the vessels a valve V (Figure 3 and Figure 7) is introduced,
which connects the vessels by meaus of pipes with a steam boiler.
From the description of the process above given with reference to the
Diagram X, a workman will understand the process to be carried on in this
apparatus; and in the further description of the working I will assume that
the whole process is in full operation, and that the polysulphurets in the vessel
A had just been completely transformed into hyposulphites by means of the
sulphurous acid gas which had been set free in the other vessel A', and also
that this latter vessel A¹ had just been refilled with fresh liquor or lye. The
valve H is shut, and the valve H¹ (Figure 7 and Figure 4) is opened, and
muriatic acid is run through the earthenware pipe T into the vessel A.
Sulphurous acid gas will be at once formed, and flows through the pipe R,
Figure 2, into the liquor of the vessel A², where it will decompose the poly-
sulphurets. Any small excess of sulphurous acid gas can escape through the
tap Hand by the pipe r¹. As soon as a sufficient quantity of muriatic acid
has been introduced into the vessel A the steam valve V is opened, and thus
the last particles of sulphurous acid gas are forced over into the vessel A'.
The sulphur, together with the liquor from which it has been precipitated, is
run out from the vessel A, and that vessel A is to be supplied with liquor or
Iye from the large stone cistern. The tap H is now to be opened, and the
tap H shut, and the contents of the vessel A are treated in a similar manner
with muriatic acid. The sulphurous acid which is liberated flows through
the pipe R into the vessel A and decomposes the polysulphurets, and any
excess of it escapes through the tap H, and gets away by the pipe r.
the requisite quantity of muriatic acid has been run in for the decomposition,
steam is to be allowed to enter into the vessel A through the valve V, in order
to drive off any sulphurous acid gas remaining in the liquor or lye. The
sulphur with the liquor is afterwards removed from the vessel A through O,
and the vessel A is to be supplied with fresh liquor or lye. The position of
the taps Hand H¹ is to be reversed, and the decomposition with muriatic acid
will next take place in the vessel A', and in like manner to that just described,
and in this manner is the process continually carried on in the apparatus.
The vessels A and A¹ are supplied with the liquor or lye up to the line of the
flanges, which connect with their covers B and B¹. e¹ and e" (Figure 3) on
the front side of the vessels are taps through which samples. are taken, in
order to ascertain whether or not a sufficient quantity of muriatic acid has been
used. To ascertain how long steam from the steam boiler ought to be passed
through the liquor in order to insure that the whole of the sulphurous acid
gas is carried over to the other vessel, another small trial tap e (Figure 3) is
After

page_text: fixed into the front side of the apparatus, and steam is blown in till on
opening the tap e no more smell of sulphurous acid gas is perceptible. The
precipitated sulphur when run off from the apparatus is collected in a cistern,
which is furnished with a false double bottom serving as a filter. The liquor
in which the sulphur was kept suspended, and which is composed of chloride
of calcium, drains off, leaving the sulphur on the filter in a granular or gritty
state, and the same is washed with a small quantity of water.
The decomposition of the liquor or lye produced as above described, and
which contains a uniform and proper proportion of polysulphurets and of hypo-
sulphites in relation to each other, may be also accomplished by pouring boiling
liquor or lye into a vessel charged with muriatic acid until the acid has been
neutralized by the lime basis of the polysulphurets and hyposulphites, which
is tested in the usual manner. The polysulphurets and hyposulphites instantly
decompose each other, the result being sulphur, and there are no gases lost.
But this modification of the manipulation is less perfect than when carried out
in my decomposing apparatus just described.
In order to obtain the sulphur in a solid state, and in a refined and almost
chemically pure form, the sulphur collected on the filter as before described,
and whilst it is in a still moist state, is introduced into a steam boiler capable
of sustaining and working under a pressure of one and a half atmospheres.
The grains of sulphur are mixed with as much water as will reduce the whole
to a thin and fluid mass, and as a precaution a little slaked lime is added in
the state called milk of lime, in order to neutralize any free muriatic acid.
The boiler it is preferred should be heated by steam from another boiler, in
place of the direct action of fire, and so as to maintain a pressure in the
boiler of about one and a half atmospheres. The mass in the boiler is to be
kept in constant motion by a stirrer worked by any suitable power. In a
short time the sulphur will be melted; after being allowed to settle it is to be
drawn off through a valve, and it may be cast into any form desired. After
the whole of the sulphur has thus been removed from the boiler the water
containing the crystals of gypsum is to be run off. The boiler is to be
furnished with a manometer, in order to read off at any moment the pressure
of steam, and if the boiler be heated by direct fire it is to be provided with
safety valves.
I claim the process first herein-before described of treating soda waste so
as to obtain sulphur therefrom.
I also claim the decomposing soda waste liquor containing polysulphurets
and byposulphites in suitable proportions, as herein described, by pouring it
whilst hot into muriatic acid.

page_text: I also claim the refining the crude sulphur obtained from soda waste by
melting it under water heated in a close vessel with pressure, as herein-
before described.
In witness whereof, I, the said Max Schaffner, have herennto set my
hand and seal, this Fifth day of March, in the year of our Lord One
thousand eight hundred and sixty-six.