IMPROVEMENTS IN THE PRODUCTION OF ALKALI CARBONATES AND IN APPARATUS THEREFOR
Year: 1884

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I, PETER JENSEN of 33. Chancery Lane, in the County of Midlesex Fellow of
the Institute of Patent Agents do hereby declare the nature of said Invention for
IMPROVEMENTS IN THE PRODUCTION OF ALKALI CARBONATES AND IN APPARATUS
THEREFOR" (a communication to me from abroad by Adolph Vogt and August
Figge, both of Westerhausen, near Magdeburg Germany Civil Engineers) and
in what manner the same is to be performed. to bo particularly described and
ascertained in and by the following statement:-
Chloride of potash and gypsum in a finely powdered state are intimately mixed
with caustic magnesia, kneaded moist, and then dried. The resulting porous mass
is broken up into small granules, of about as nearly the same size as possible, and
then treated with. superheated steam in the sulphating furnace at a bright red heat,
which furnace is to be described below.
All chlorine will thereby be driven out in the form of hydrochloric acid, while a
mixture of sulphate of potash, and oxides of calcium and of magnesium remains in
the furnace; the hydrochloric acid thus produced as a by product is either
condensed as such or transformed into chlorine in a special apparatus heated by the
surplus heat of the furnace according to known methods and utilized. The cost of
this conversion of the hydrochloric acid into chlorine.in a special apparatus may
however be avoided by mixing with steam used for driving out the hydrochloric
acid a corresponding quantity of free oxygen; the porous mixture of chloride and.
sulphate which is traversed by the mixture of E CI and O then acts as a Deacon's
contact substance and no more HCl gas flows out of the furnace, but Cl and H₂O.
This moist chlorine gas which of course contains some hydrochloric acid may
be freed from HCl and H₂O and in the ordinary manner be made into chloride
of lime.
All the chloride of potash in the aforesaid mixture having been converted into
sulphate of potash, the so produced mixture (which after removal from the sulphate
furnace is in just as porous and loose a state as that of the other) is now placed
into vertical cast iron retorts which are constructed and fired similarly to the
sulphate retorts.

page_text: In order to reduce this sulphate mixture preheated carbonic oxide gas is
introduced into the mass from above and caused to flow through it. The carbonic
oxide gas combines with the oxygen contained in the sulphates forming carbon
dioxide, which flows off at the lower ends of the retorts.
The flow of carbonic oxide is continued at as constant a temperature as possible
until the sulphate is converted into sulphide. The supply of carbonic oxide is then
interrupted, the fire lowered and a mixture of CO, and H₂O passed through the
retort the opposite way which the carbonic oxide took. The sulphur in the sulphide
will thereby be converted into H, S and the sulphide itself into carbonate. This
conversion completed, the gas supply is interrupted and the retort emptied.
Where in this description potash is named soda may be substituted and of course
also a mixture of both. Besides the alkali chlorides, alkali sulphates may also be
admixed; these latter remain unchanged in the sulphating operation.
As the caustic magnesia used as an addition only serves the purpose to render
the chloride mass porous and fusible by the temperature used, silicious acid, clay or
lime may be substituted.
The alkali chlorides may also, instead of being mixed with gypsum and caustic
magnesia be mixed with sulphate of magnesia (MgSO) and caustic. magnesia or
lime, as by the latter mixture the alkali chlorides when treated with steam or
moist air are also converted into sulphates. All sulphates produced in any of the
aforesaid mixtures according to the above method, or such which are rendered by
other and known methods may, in case they are in a porous state and not fusible
by red heat be converted into carbonates according to the above described mode of
reduction and then of carbonisation, in the manner of the sulphate of potash
produced from chloride of potash.
These carbonates are then lixiviated cold, and soda or potash produced therefrom,
in the known manner all according to the alkali chlorides or alkali sulphates
employed. In the carrying out of these processes the following has to be observed.
For the sulphate process the steam employed must be heated as much as possible.
The pipes and valves for the carrying away of the HCl may be of cast iron, as the
retorts; these must however always be heated so much, that the HCl mixed with
steam shall not condense.
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The carbonic oxide is produced by working a generator fed with coke with pure
oxygen; this is however not absolutely necessary for instead of the oxygen dry air
may be used as nitrogen in the carbonic oxide does not hurt, and is only
inconvenient because, of the increase in the bulk of gas,
But it is important that the carbonic oxide should be free from hydrogen or
hydrogen compounds, wherefore also a coal as free as possible from hydrogen should
be used for the forming of the carbonic oxide. The temperature of the latter
should in the beginning of the reduction operation be raised in order that the upper
layers of the materials to be reduced should keep the proper temperature, whereas
it is well towards the close of the operation to admit the CO gas in a cooled state,
because the upper layers have already been reduced and become cooled down by the
cold stream of gas and thus become sufficiently prepared for the following
carbonizing process.
The CO₂ formed by the reduction is used for this latter process. This may in
continuous working be effected directly with a battery of connected retorts or by
storing it in a gas holder. The mixture of the CO, with steam, as required for the
carbonizing process may be done by forcing it into the retorts by means of a well
regulated steam injector or by passing it through warm water of a certain
temperature.
The apparatus required for carrying out this process is shown on a much reduced
scale on the accompanying two sheets of drawings.
Sheet I represents the sulphating furnace, Figure 1 being a vertical central
section. Figure a cross section through upper part of furnace on line x, y and
Figure 3 a cross section through the lower part on line w z.

page_text: Sheet II shows the reducing and carbonizing furnaces, Figure 1 being a central
vertical section through such a furnace Figure 2 a plan Figure 3 a cross_section
through upper part on line u, x, and Figure 4 a cross section on line y z. Figure 5
is a vertical longitudinal section through a battery of several such furnaces and
Figure 6 a cross section near the top.
Referring now to Sheet 1 the sulphating apparatus consists of a furnace heated
either by generator gas as indicated in Figure 1 or by direct firing. It contains a
large retort A and a small retort a both of cast iron.
The retort A serves for the sulphating proper, while the retort a serves for
preheating the material.
The retort A constructed of separate superposed cast iron tubes the bottom one
of which has an end piece that can be closed tightly and that serves for emptying
the sulphated mass, and which also contains the inlet pipes D₁ D₂ D, D₁ for the
gases and rests on the brickwork, the uppermost tube has a large sliding hopper for
charging the retort and a small shank for outlet of the gases.
The uppermost tubes are by means of rods S, levers H with fulcrum brackets T
resting on the brickwork and counterweights G suspended in such manner that
only a very small part of its weight comes on the next lower tubes. That part of
the rods S which is exposed to the beat of the fire is protected by a tube of
fireproof material.
If this suspension arrangement were dispensed with and the lower part of the
brickwork made stronger the high heat to which the brickwork and the cast iron
are exposed would by the greater expansion of the cast iron cause it to bulge.
The preheater a is arranged over the retort A in such manner that the discharge
opening of the former is over the charging opening of the latter, and the contents
of a can be dropped direct into A for which purpose the slides fu and Fo are
provided. The preheater a as well as the retort A are set in brickwork and
heated by the heat and flame escaping from the latter. When for sulphating, the
alkali chlorides are treated with steam and free oxygen instead of with steam
alone the inner metallic surface of the retort A must be protected by a lining of
silicious enamel against the chlorine produced.
The retort A for reducing and carbonizing shown on sheet II consists similarly
of one or more cylindrical tubular parts which are placed on the top of each other
and set in brickwork. At the top it has a charging hole with cover and below it
has two slanting discharge openings with covers; q is a flap grate above same.
The retort is heated equally by generator gases from top to bottom, the gas entering
by the pipes C and the air by the pipes L and the holes e and passing into the
combustion chamber F so that the flame can play round the retort A everywhere
in the annular space f. The products of combustion pass down through the flue D
into the chimney flue B. Or the retort may of course if desired be heated from
bottom to top by gas or direct fire in the ordinary manner.
When the retort consists of several pieces of tube, these are, as in the case of
sulphating retorts, suspended by rods levers and counterweights as seen in Figures
1 and 2 Sheet II.
The use of the valves and pipes shown in Figures 5 and 6 will be best understood
from the following description of the action.
Beginning with the sulphating process and supposing the work in full operation
the preheater a Sheet I is supposed to be filled with preheated chloride mixture,
the retort A filled with red hot chloride mixture and the inlet and outlet openings
for all the gases, and steam closed, while the mass contained in the lower part of A
is perfectly sulphated.
The discharging lid Fu at bottom of A is now opened and a volume of sulphate
mixture equal to the contents of the preheater a is discharged into the cart W
placed below it. The lid Fu is then closed, and the slides Fo and fu opened
when the contents of the preheater a will drop into and refill the retort A. These
slides being again closed the lid fo is opened and the preheater a filled with fresh
material. The outlet pipe R for the hydrochloric acid (or chlorine) is now opened

page_text: so also the inlet pipes D₁ D₂ D D for steam, whereupon H Cl will be generated
(or for steam and air, whereby chlorine generated). The retort works periodically
that is to say at certain intervals a certain quantity of preheated material is
entered, and an equivalent quantity of made sulphate mixture drawn off below.
This mode of action is continually repeated and as regularly as possible.
We now come to the reducing and carbonizing process illustrated on Sheet II.
Supposing the retort A sheet II is freshly charged with sulphate mixtures or
sulphates and the outlet openings and all the valves are closed and the fire for
some time in such a state that the contents of the retort are red hot. The inlet
valve K₁ Figure 5 for the CO gas and the outlet valve. V 6 Figure 6 for the
generated CO, are opened, and the supply of the CO gas is kept up until the
sulphates are quite converted into sulphides, during which operation towards its
close the CO₂ mixed with CO escapes by the valve V Figure 6.
The fire is now lowered, the valve K₁ and V, Figures 5 and 6 closed and the
inlet valve K, Figure 5 for the mixture of CO₂ and steam opened the outlet valve V
Figure 6 for the generated H. S is also opened and kept open till the carbonisation
of the mass is completed.
The retort is then emptied and charged afresh and the operation commenced
again.
It is clear that in such working only a small part of the generated CO₂
and of H, S could be applied. It is therefore necessary to combine a number of
retorts into a battery, and to work them so, that the only incompletely oxidised CO
may in a second retort containing fresh sulphate mixture be oxidised into an again
applicable CO and so also that the H, S passing off from the first carbonizing
retort may be quite freed from CO₂ by passing through a second retort. The value
of this arrangement therefore does not only consist in that the supplied gas-
comes into full action, but that the gases obtained as by-products may be further
utilized.
The mode of combining several retorts to a battery is illustrated by Figures 5
and 6, where the pipes R, R. R. form the connection between the retorts for
conveying further the unused CO gases and the pipes R R R R for conveying.
further the incompletely used carbon dioxide.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed I declare that what
I claim as the invention communicated to me is :—
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First-The mode of uniting the sulphuric acid with alkalis by treating the
gypsum mixed with alkali chlorides at red heat in an unmelted state with steam
with or without the admixture of free oxygen substantially as set forth.
Second-The employment of magnesia clay silicious earth or lime, separately
or in conjunction with a mixture of gypsum and alkali chlorides for the purpose of
rendering the latter infusible at red heat and porous for the treatment with steam
or moist air substantially as set forth.
Third: The employment of caustic magnesia or lime, separately or combined
with a mixture of alkali chlorides and sulphate of magnesia for the purpose of
rendering the alkali chlorides infusible at red heat and porous for treatment
with steam or moist air for sulphatizing the chlorides, substantially as set forth.
Fourth The apparatus for converting the alkali chlorides into sulphates
consisting mainly in the sulphating retort A the preheater a and the connecting
slides Fo and fu between A and a substantially, as set forth.
Fifth-Enamelling the inner surface of the iron sulphating retort by means
of silicates for the purpose of protecting it against the dissolving influence of the
chlorine developed in the retort.
Sixth-The mode of converting alkali sulphates into carbonates consisting in
reducing the sulphates in a porous loose state and broken into small granules of
about the same size at red heat by passing through them dry carbonic oxide as free
as possible from hydrogen and converting the sulphides in the same retort but at
a sensibly lower temperature into carbonates by passing a mixture of carbon

page_text: di-oxide and steam through the same, the carbonic oxide being passed in from
above and the carbon di-oxide and H, O from below substantially as set forth.
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Seventh-The apparatus for carrying out the method sixthly claimed viz :-
a system of upright retorts which are connected with each other by pipes and by
the following valves:-the valves K, for the inlet of the carbonic oxide into the
retorts, the valves V, V, and V. for conducting further the incompletely used
carbonic oxide gases from one retort to the other, the valves Ve Ve for carrying off
the pure carbon dioxide, the valves K, K₂ for letting in the mixture of CO₂
and H, O, the valves V₁ V₁ and V2 V₂ for carrying further the incompletely used
mixture of CO, and H, O, and the valves V, V, for carrying off the pure H, S all
substantially as set forth.
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Eighth The mode of taking the weight of the upper parts of the retorts from
off the lower parts by means of counterweights G rods S and levers H (sheets 1
and 2) which are supported by the brickwork substantially as set forth.
Dated this fourteenth day of October 1884.
BREWER & JENSEN,
For the Applicant.