Improvements in the Manufacture or Production of Sulphuric Anhydride and Means to be Employed therein
Year: 1899

page_text: 66
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture or Production of Sulphuric
Anhydride and Means to be Employed therein "
I, GEORGE WILLIAM JOHNSON of 47 Lincoln's Inn Fields in the County of London,
Patent Agent, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by the Firm of Verein Chemischer Fabriken in
Mannheim and Adolf Clemm both of Mannheim in the German Empire) to be as
follows:
It has been proposed to convert sulphurous acid into sulphuric anhydride by means
of finely divided platinum but the heat of the reaction of sulphurous acid and oxygen
upon the platinum prevented the perfect combination of the two gases and a further
disadvantage is that the impurities with which commercial sulphurous acid is charged
settle upon the platinum and make it inoperative. To overcome these defects it was
necessary to use cooling apparatus and also to submit the gases before they enter the
contact space to a careful and complicated purifying process. Burnt pyrites have
also been used as contact substance in a process described in the Specification of
Patent 17266 of 1898
This has proved theoretically perfect but difficulties arise in the installation of the
apparatus. The object of this invention is to overcome the objections hitherto
experienced.
According to this invention roaster gases are first conducted over highly heated
burnt pyrites or substances containing ferric oxide and then are subjected to a dry
filtering process and they are then admitted to the platinum contact substance.
The said filtering is conducted mechanically in a receiver containing acid proof and
fire proof material which may be in the condition of grains of a predetermined size
calculated according to the effect desired or in the condition of dry fibrous or felted
material.
is
The resistance of the platinum contact mass to the passage of the gases
overcome by making the platinum or platinized material in the form of a grating
network or fabric which may be carried by a frame or frames within the contact
space the gas current may pass through the contact mass in any desired direction
The formation of sulphuric
horizontally or vertically downwards or upwards.
anhydride takes place in a considerable degree before the gases reach the platinum
substance and therefore excessive heating in the contact space is avoided without the
use of cooling apparatus.
1
1000

page_text: 66 Improvements in the Manufacture or Production of Sulphuric
Anhydride and Means to be Employed therein."
I, GEORGE WILLIAM JOHNSON of 47 Lincolns Inn Fields in the County of London,
Patent Agent, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by the Firm of Verein Chemischer Fabriken in Mann-
heim and Adolf Clemm both of Mannheim in the German Empire) and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
It has been proposed to convert sulphurous acid into sulphuric anhydride by means
of finely divided platinum but the heat of the reaction of sulphurous acid and oxygen
upon the platinum has prevented the perfect combination of the two gases and a
further disadvantage is that the impurities with which technical sulphurous acid is
charged settle upon the platinum and in a short time render it inoperative. To over-
come these defects it has hitherto been necessary to use cooling apparatus to reduce
the heat evolved during the reaction, and it has also been necessary to submit the
gases, before they enter the contact space, or chamber, to a careful and complicated
washing, or purifying process by thoroughly mixing the gases with the washing liquid
until tests shew that all injurious constituents have been removed.
Burnt pyrites or analogous substances containing ferric oxide, have also been used
as contact substance in a process described in the Specification of Letters Patent
No 17266 of 1898 granted to me on a communication from my foreign correspondents
the sulphurous acid being produced by roasting sulphurous pyrites with the admission
of previously dried air, the gases thus obtained being brought into contact with the
burnt pyrites or other substance containing ferric oxide at the same temperature as
that of the roasting chamber. Although this may be regarded to give good results,
for obtaining such results in actual practice complications are necessary in the
installation of the apparatus, because in order to obtain a theoretical yield of anhydride
it is necessary to lead the gases repeatedly over the burnt ore having which-has-
previously absorbed the anhydride formed by the preceding reaction, and it is
desirable to avoid these repeated operations. The object of this invention is to over-
come the objections hitherto experienced and this is done principally by combining
the aforesaid two processes with the interposition of a dry filtering operation.
According to this invention the roaster gases produced from sulphurous pyrites with
the admission of previously dried air are conducted once only over highly heated
burnt pyrites, or other substance containing ferric oxide, and afterwards the said gases
are subjected to dry filtering and they are afterwards admitted to the platinum contact
space, or chamber, by which means the advantages of both methods above referred to
are obtained, whilst their disadvantages are avoided.
While the gases (produced with the use of previously dried air) pass over the burnt
pyrites, or other substance containing ferric oxide, not only is a considerable part of
the sulphurous acid converted into sulphuric anhydride but the gases are also at the
same time purified, partly by mechanical filtration and partly by chemical absorption
so that they do not injure the platinum contact substance subsequently used.
Furthermore, owing to a considerable part of the sulphurous acid being converted
into sulphuric anhydride as the gases pass once over the burnt pyrites, or other
substance containing ferric oxide, the proportion of sulphurous acid still present in
the gases is so materially reduced before the gases enter the platinum contact space,
or chamber, that by the time the said gases come into contact with the platinum the
heat arising from reaction does not increase to a degree necessitating the employ-
ment of special cooling apparatus. As however such gases retain slight traces of

page_text: impurities which unless removed could still injure the platinum it is necessary to
subject the said gases to dry filtration before permitting them to come into contact
with the platinum and this may, if desired, be preceded by absorption of the sulphuric
anhydride already formed.
For the purpose of the filtration, granular porous substances or fibrous or felted
fabrics of acid-proof and fire-proof material, such as pumice-stone asbestos and the
like, are used.
Should the gases on their way to the platinum contact space or chamber, lose so
much of their heat that their temperature is no longer sufficient to start the re-action
with the platinum, the heat is restored to the necessary degree, which may be done
by causing the gases to pass through re-heating apparatus on their way from the
filtering apparatus to the platinum contact space or chamber. This re-heating
apparatus may be heated with advantage by the heat from the roasting furnace.
The platinum contact mass is preferably used in the form of platinized grating, or
net work or platinized fabric which may be carried by a frame, or by frames, within
the contact space, or chamber, the gases passing through the contact mass in any
desired direction, such as horizontally, or vertically downwards or upwards.
The sulphuric anhydride produced may be absorbed by sulphuric acid in the well
known or any suitable manner.
Having now particularly described and ascertained the nature of this invention and
in what manner the same is to be performed I declare that what I claim is :-
In the manufacture, or production of sulphuric anhydride the combined employ-
ment of burnt pyrites, or other substance containing ferric oxide, and of platinum as
contact substances with the interposition of dry filtering substantially as hereinbefore
described.
Dated the 7th day of Art 1000