Process for Purifying and Decolorising Saccharine Julces and Sugar Solutions.
Year: 1893

page_text: Date of Application, 28th Oct., 1893-Accepted, 27th Oct., 1894
Process for Purifying and Decolorising Saccharine Julces and Sugar
Solutions.
I, CARL STEFFEN, of IV. Heugasse 10, Vienna in the Empire of Austria,
Gentleman, 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:-
In the Specification to my Application for Letters Patent No. 17632 dated
19th September 1893 I have described a process for purifying and decolorising
saccharine juices and sugar solutions generally, this process consisting mainly in
subjecting the juices, obtained in the usual manner by defecation, in some cases
saturated with carbonic acid, and separated from the saturation and defecation
sediments, or in subjecting the sugar solutions which it is desired to purify. after
cooling them to below 60° C. (preferably between 30° and 40°, or lower) to the
action of sufficient quantities of sulphurous acid that the coloring and non-
saccharine matters of the juice should enter, as much as possible, into sulphite
and acid sulphite compounds which remain in solution in the acid-reacting juices
or sugar solutions, whereafter these compounds of the coloring and non-saccharine
matters are removed from the acid juices or sugar solutions by filtering them
through animal charcoal, within the above mentioned limits of temperature;
finally the acid still existing in the filtered juices or solutions is precipitated as
insoluble salt by the action of suitable quantities of lime (or baryta, strontia,
alumina, etc.) in such a manner that the juices or sugar solutions, after being
freed from the precipitate, shew a slightly alkaline or even a neutral reaction,
before they are boiled or evaporated.
Now I have discovered that it is also possible to obtain a satisfactory purification
and decoloration of the juices or sugar solutions treated, as above described, with
sulphurous acid, and showing an acid reaction, by mixing them, without any
previous filtration through animal charcoal, at a temperature lower than 60° cent.
(preferably comprised between 30°-40°, or lower) with sufficient quantites of lime
(or baryta, strontia, alumina, etc.) in order to neutralize and to precipitate the free
acid. The action of the sulphurous acid in sufficiently large quantities (to 100 parts
of cooled defecation juice the percentage of acid should be according to the more
or less good quality of the beetroot or the cane, 0.1 to 0-3, expressed as sulphurous
acid) on the juices cooled to the above mentioned temperatures is of such a nature,
that without any decomposition of sugar taking place, the colouring and other non-
saccharine constituents of the juice undergo in their composition a change that is
favorable to the ulterior transformation of the juices into filling-mass, and enter,
within the acid juice, as far as is possible, into sulphite and acid sulphite com-
binations, part of which are precipitated together with the acid in excess when the
juice is treated for that purpose, previous to the further operations and the heating
same, with lime (or baryta, strontia, alumina, etc.); in this manner it is possible
to obtain very slightly coloured and easily crystallizable filling masses with thin
fluid syrups, without any destruction of sugar taking place during the operations
required for that purpose.
of
The neutralized or slightly alkaline reacting juice, after it has been freed from
the precipitate in the usual way by means of mechanical filters (filterpresses, bag-
filters, etc.) may either be immediately evaporated and boiled to grain, or be
submitted over and over again to the aforesaid treatment with sulphurous acid and
subsequent neutralization such repetition of the process being resorted to at any
stage of the manufacture in order to attain a higher degree of decoloration and

page_text: purification; or finally the said juice may be filtered in the usual way through
animal charcoal.
The above described process is applicable as well to thin juices as, for the
same purpose, to medium and thick juices of all degrees of concentration, and
also to all syrups of the sugar manufactories and to sugar solutions of every
kind, such as the cleares or fine liquors of beet sugar and cane sugar refining
works, and to the syrups thereof.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A process for obtaining decolorised and purified sugar solutions by treatment
of the juices of beetroot and cane-sugar manufacture, defecated in the usual way,
and in some cases saturated with carbonic acid, freed from the defecation and
saturation scum, and cooled down to below 60° cent. (preferably between 30°
and 40°, or lower) with sulphurous acid in such quantities that the coloring and
other non-saccharine matters are as much as possible made to form sulphite or acid
sulphite combinations which remain in solution in the said acid-reacting juices, part
of said combinations being thereafter precipitated together with the acid in excess
by the action of suitable quantities of lime (or of baryta, strontia, alumina etc.)
resulting in a slightly alkaline or even a neutral reaction of the juices when the
same are freed from the precipitate, said juices being afterwards, if desired, filtered
through small quantities of animal charcoal in order to obtain a higher degree of
decolorisation and purification or being further operated upon the usual way.
without any previous filtration through animal charcoal, substantially as set forth.
2. The application of the process referred to in the first claim to medium and
thick juices of any degree of concentration as well as to all syrups of the sugar-
manufacture, as and for the purpose set forth.
3. The repeated application of the process referred to in the first claim to sugar
solutions that have been already partly decolorised and purified by the same
process, said repetition being resorted to at any stage of the manufacture in order
to attain a higher degree of decoloration and purification, as set forth.
4. The application of the above described process to the cleares or fine-liquors
of beet-sugar and cane-sugar refining-works, and to the syrups thereof, substantially
as set forth.
Dated this 28th day of October 1802