IMPROVED PROCESSES AND MEANS FOR ABSORBING AND UTILISING ACID GASES AND FUMES, MORE PARTICULARLY SULPHUROUS ACID FUMES
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Clemens Winkler at the Office of
the Commissioners of Patents on the 29th October 1880.
CLEMENS WINKLER, of Freiberg, in the Kingdom of Saxony. "IMPROVED
PROCESSES AND MEANS FOR ABSORBING AND UTILISING ACID GASES AND FUMES,
MORE PARTICULARLY SULPHUROUS ACID FUMES."
According to my present Invention the gas fumes or vapour which it is desired
to deprive of its acid constituents is passed through chambers, towers, or other
suitable closed spaces which contain a suitable metal in any convenient form or
quality, over which water is made to trickle, and which serves to absorb the said
acid constituents of the gas or vapour. For this purpose it is preferred to employ
those metals that effect the decomposition of water, iron being the best suited for
the purpose, and in the following description the use of this metal will be assumed.
In passing in acid gas through a layer of iron moistened with water, the iron
will be acted upon, and the acid, whether in the form of gas, vapour, or spray, will
be retained in the form of a salt of iron. Thus hydrochloric acid will give
protochloride of iron; sulphuric acid, protosulphate of iron, &c., which salts may be
obtained in a solid state by evaporation. If sulphurous acid in any state of
dilution is brought together with iron in the presence of water, a liquid is produced
under violent ebulition, which contains principally compounds of hydrosulphurous
and hyposulphurous acids with ferrous oxides in which, however, other compounds,
such as those formed by tetrathionic, sulphurous and sulphuric acids with ferrous
oxides, appear more or less as secondary products. The carbon of the iron, or when
using tin plate, the tin, remain unchanged. The ferrous solution obtained when
using sulphurous acid, is treated in various ways, according to the products desired to
be obtained; thus according to one method the solution is evaporated to dryness, and
the residuum, with or without addition of a metallic sulphate, such as pyrites, is
calcined or roasted under admission of air; hereby are produced, firstly, again
sulphurous acid gas, but at a degree of concentration available for conversion into
sulphuric acid, and, secondly, ferrous oxide, which is either utilised direct or is
reduced to metallic iron and again used for the above purpose.
According to another method the ferrous solution is placed in a vessel heated by
a steam coil or other suitable means and provided with a discharge pipe, in which
vessel is also introduced either a sufficient quantity of sulphuric acid for the
conversion of the iron contained in the solution into sulphate, or a sufficient quantity

page_text: of hydrochloric acid for converting the iron into protochloride. Three products are
thus obtained: Firstly, pure sulphurous acid, which is either conducted into a lead
chamber to be treated in the usual manner for the manufacture of sulphuric acid,
or which may be converted into sulphites or hyposulphites; secondly, sulphur in
the form of a dense precipitate, which is melted down and run into moulds for
commercial use; thirdly, oil of vitriol, or solution of protochloride of iron, which is
evaporated as far as may be requisite for effecting its crystallisation.
In like manner, as above described, other metals, such as zinc, may be employed
for the removal of the acid constituents from the gases, and the products may be
rendered commercially available by the use of chemical re-actions similar to those
above set forth.