Improvements in the Treatment of Raw Sugar for Purifying and Drying the same.
Year: 1892

page_text: Date of Application, 30th Nov., 1892-Accepted, 14th Jan., 1893
COMPLETE SPECIFICATION.
Improvements in the Treatment of Raw Sugar for Purifying and
Drying the same.
A communication by FEDERICO SCHIAFFINO, of the Ligure-Lombarda Sugar
Refinery of Sampierdarena, in the Kingdom of Italy, Director.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool and 6 Bank Street, Manchester,
both in the County of Lancaster, and 323 High Holborn in the County of
Middlesex, Civil Engineer, 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 :-
This invention has for its object an improved process for purifying and cleaning
raw sugar.
In sugar in general, and more particularly in beetroot sugar, the crystals are
coated with impurities and colouring matters, whilst inside they are almost absolutely
pure. In fact, by submitting raw sugar, and more particularly beetroot sugar to a
steam centrifugalling or to a systematic clarification, there is obtained on the one
hand a discoloured and impure syrup and on the other hand white crystals almost
entirely freed from foreign matters. This object is at present attained by a
clarification by means of steam, or water or more or less rich or concentrated
syrups.
By this invention it is proposed to obtain these results in an even more perfect
manner. The invention consists in the intimate mixture of raw sugar with a
substance, either in a fine powder or in small particles acting by absorption and
friction.
Wheat flour, starch or the like may be employed for this purpose, but it is
preferable to make use of wood sawdust, cork, bran or other like very absorbent
substance which may be separated from the sugar and very easily cleaned by
washing.
The mixing is performed by means of an ordinary mixing apparatus, care being
taken to avoid breaking the sugar crystals by friction.
After having remained a certain time in contact, the impurities adhering to the
surface of the crystals are absorbed by the substance mixed with the sugar and
the crystals are obtained perfectly pure and polished. The above mentioned
substance may then be easily separated by means of an arrangement of sieves or
fans or even by these two kinds of apparatus combined according to the nature of
the mixing substance employed.
The residue (sawdust, cork, etcetera) is then washed preferably in a turbine, or
in a filter press in order to separate the molasses therefrom and to cleanse them in
order that they may serve for another operation after having been suitably dried
and so on continuously. The word suitably is made use of to show that it
is not always necessary to completely dry the substance employed, but on the
contrary it may sometimes be preferable to leave a certain amount of moisture
therein.
The quantity of the detergent substance to be used should be proportionate to
the purity and degree of moisture of the raw sugar which it is intended to treat
and it may vary between somewhat wide limits.
After the two operations above described, namely, 1st. the intimate mixture of
the sugar with a solid pulverised or granulated substance, 2nd. the separation of
the substance which has been mixed with the sugar, the result will be an almost
complete separation of the molasses, which by other methods of treatment is only
obtained at greater expense and less thoroughly.

page_text: The sugar thus cleaned may be refined more cheaply and with a greater effective
return.
If it be desired to obtain directly a sugar fit for consumption, it is necessary and
it will suffice to pass the' sugar, cleaned in the manner hereinbefore described,
through one of the many brushing or scrubbing machines commonly used in mills
for polishing rice, seeing it is only a question of rubbing the sugar crystals in
order to remove the dust with which they are still coated.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is-
1. The cleaning of raw sugar crystals by means of intimately mixing therewith
a heterogeneous solid substance, in a fine powder, or in small particles, which
removes by friction and absorption the impurities of the sugar crystals, rendering
them almost absolutely pure and dry.
2. In the treatment of raw sugar as specified in Claim 1, separating the hetero-
geneous solid substances, extracting the molasses and again drying the residue
substantially as hereinbefore described.
3. The various processes constituting in their entirety the improvements in the
treatment of raw sugar substantially as hereinbefore described.
Dated this 29th day of November 1892.
WM. P. THOMPSON & Co.,
Agents for the Applicant.