An Improved Process for the Extraction of Fats and Oils from Substances containing the same by Means of Sulphurous Acid.
Year: 1889

page_text: Date of Application, 11th Dec., 1859-Accepted, 11th Jan., 1890
COMPLETE SPECIFICATION.
An Improved Process for the Extraction of Fats and Oils from
Substances containing the same by Means of Sulphurous Acid.
We, WILHELM GRILLO proprietor of manufactory and Dr. MAX SCHROEDER,
Chemist, both of Neumühl-Hamborn in the German Empire do hereby declare the
nature of this invention and in what manner the same is to be performed. to be
particularly described and ascertained in and by the following statement :-
The process of this invention is based on the hitherto unknown fact that the
compressed sulphurous acid SO2 is a good solvent of fats and oils.
The liquid
sulphurous acid does not in all proportions combine with fats and oils to form a
homogeneous liquid. The proportions of solubility are however such that the
extraction from fatty materials by means of compressed liquid sulphurous acid may
be effected in a manner similar to that by benzine or carbon sulphuret and in a
shorter time.
So long as the relative quantity of the fat or oil is in excess the mixture of
compressed SO² and it, is thoroughly good. It is not so good when the sulphurous
acid is in excess, for then, especially at low temperatures-30° Celsius and under-
which vary according to the nature of the fat or oil, a formation takes place of
liquid columns one over another, the upper ones of which contain relatively more
oil than sulphurous acid whilst the lower heavier liquid consists mainly of SO² with
only a small quantity of oil in solution, however, upon increase of temperature an
intimate mixing takes place in this case also. Accordingly, although the dissolving
properties of the liquid SO2 are not wholly so good for fats and oils as the other
means used for extraction purposes. yet the SO2 has advantages which compensate
for the disadvantage referred to, which in practice is scarcely observable, for instance
with the use of SO³ there is less danger of extracting the works taking fire, and in
consequence of the low temperature-10° Celsius-at which it boils, it may be
removed from the fats or oils and from the material extracted from, much easier
than other inedia of extraction.
The performance of the extraction process by means of SO* does not greatly
differ from that of known processes. It is only to be observed that the extraction,
corresponding to the nature of SO2, must take place under a higher pressure than
that obtaining with the usual solvents, therefore the apparatus is made stronger, as
at an ordinary extracting temperature of from 30° to 40° Celsius a pressure of from
five to six atmospheres has to be taken into account. The process may be per-
formed on the contrary current principle in communicating cylinders or more simply
and with the use of a smaller quantity of the solvent by distillation.
In the latter case we prefer to employ a stationary iron cylinder provided with the
necessary tight closing apertures for the introduction and discharge of the material
and with a grating or sieve for sorting the same. Under the sieve there is a steam
worm apparatus, also apertures closeable by valves for introducing the liquid SO
and for discharging the fat or oil. Provision is also made of safety valve with
discharge pipe, manometer, thermometer, and the top cover has an orifice closeable
by a valve, which orifice is in connection by a pipe with a rising cooling worm
placed above. As, owing to its low boiling point, the liquid SO must be employed
under pressure another valve is required by which the cooling worm may, during
the process, be closed at its upper end.
The apparatus having been charged with material from which fat or oil is to be
extracted, and the apertures closed, the necessary quantity of SO2 in a liquid state
is let into the apparatus under pressure. Simultaneously therewith, the air which
contains SO2 is blown past the upper valve of the cooling worm and rendered
uninjurious in the usual way. The liquid SO2 is then gradually heated by the steam

page_text: worm to 30°-40° Celsius whereby a pressure of from 5 to 6 atmospheres is generated
in the apparatus. The gasifying SO2 ascends into the fat or oil containing material,
is partly condensed therein and flows back mixed with fat or oil. As soon as the
material acquires the said temperature, the further condensation is effected by, and
the continuous backward flow of the SO2 through the worn cooled by water. When
the extraction process is completed which according to the size of the pieces of the
material treated and density of the same, may require from some hours to some
days, the solution of oil or fat in SO2 at the bottom, is, for the purpose of removing
the SO subjected to distillation either in the apparatus direct or in a special vessel.
In the distillation the aforesaid cooling worm is operated in the contrary direction,
the worm at its bottom end being placed in communication with a closed vessel
serving as a reservoir for the liquid SO². A compressor or forcing apparatus is
used for drawing off by suction the SO2 gases present in the apparatus and forcing
them in a liquid form back into the reservoir. The SO2 remaining behind in the
material may be completely removed by means of a steam or air blast. If steam
is used it is requisite for the apparatus in which the operation is effected to be
lined with lead owing to the acid properties of the watery SO² solution formed at
the time.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is:
The employment of liquid sulphurous acid (SO³) as a solvent for fats and oils,
especially the process for extracting fat and oils from materials containing the
same, by means of liquid sulphurous acid anhydride substantially as described.
Dated this 11th day of December 1889.
CAPITAINE & VON HERTLING,
89, Chancery Lane, London, W.C., Agents for the Applicants.