'AN IMPROVED PROCESS OF AND APPARATUS FOR THE PURIFICATION AND DECOLORIZATION OF SUGAR
Year: 1885

page_text: Decolorization of Sugar..
I, WILLIAM ROBERT LAKE, of the firm of, Haseltine, Lake & Co Patent Agents,
Southampton Buildings, in the County of Middlesex, do hereby declare the nature
of my invention for " 'AN IMPROVED PROCESS OF AND APPARATUS FOR THE
PURIFICATION AND DECOLORIZATION OF SUGAR "and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement :-
This invention relates to an improved process of, and apparatus for, removing
impurities from raw sugar.
In certain processes of manufacturing refined cane sugar, heretofore practised,
the raw sugar is first washed, by which some of its impurities are removed,.and is
then dissolved in water and filtered through bag filters, by which other impurities
are removed, preparatory to the filtration of the sugar solution through bone black.
The syrup resulting from the washing of one lot of raw sugar is sometimes
repeatedly used for mixing with other lots of raw sugar to prepare them for
washing, as described in the specification of United States Patent No 191,539,
issued to Franz O. Matthiessen, June 5, 1877, according to which the syrup is used
over and over for mixing with raw sugar until it becomes so charged with impurities
that it ceases to be useful for that purpose.
Some raw sugars of high grade contain so small a proportion of impurities that
they do not require to be washed, but may at once be dissolved in water and filtered
through filter bags for the removal of their mechanical impurities, preparatory to
filtration through bone black.
By the present invention in the process of refining raw sugar, the preliminary
filtration through bag filters is dispensed with, and the mechanical impurities are
removed from the raw sugar by mechanical means in connection with the bone
black filter itself, and while the process of filtration through bone black is being
continuously carried on.
The process embraces the following steps:-First, the raw sugar, if of low grade,
is washed to remove a portion of its impurities. Secondly, the washed raw sugar

page_text: is dissolved in water; or; if of high grade, the raw sugar is dissolved in water
without having been previously washed. Next, the sugar solution, obtained in
either of these ways, instead of being filtered through filter bags is at once filtered
through bone black, by the process of upward filtration through a column of bone
black contained in a filtering chamber, provided at the bottom with a scraper or
discharger for removing the successive strata from the base of the column, with
which the sugar solution first acquires contact, as rapidly as may be required by
the exhaustion of the decolorizing power of the bottom stratum and the presence
of mechanical and other impurities which may collect at that point.
Any suitable apparatus may be employed for washing the raw sugar, such as, for
example, that described in the specification of United States Patent N° 303,443,
dated Aug 12, 1884, granted to F. O. Matthiessen and George Dinkel.
Starting with a raw sugar from which a portion of the impurities have been
removed by washing, or with a raw sugar containing only a moderate proportion of
impurities, which therefore has not needed washing, the raw sugar is dissolved in
water, forming a solution of say 30° Beaumé, and then filtered upwardly through
bone black contained in a filtering chamber provided at the bottom with a scraper,
or other instrumentality, which, by its operation while the process of filtration is
being continuously carried on, gradually removes the exhausted bone black and the
impurities which collect at the place where the sugar solution is first brought into
contact with the bone black.
The syrup resulting from the washing of the raw sugar may also be diluted with
water and filtered in the same way.
The speed with which the scraper or other discharging instrumentality is
operated for the removal of the impurities and exhausted bone black from the
filtering chamber will of course be varied according to the quantity, and also
according to the character of the impurities present in the solution which is to be
filtered.
Among the mechanical impurities present in raw sugar are sand, clay, and
Bometimes fibre. A certain portion of them having, when necessary, been removed
by washing the raw sugar, the remainder is removed by the bone black, and 'is
collected with the exhausted bone black discharged by the scraper or discharger
from the surface of the mass of bone black with which the sugar solution is first
brought into contact.
Similarly, the impurities contained in the syrups produced by washing the raw
Bugar are removed by diluting the syrup and filtering it through a bone black filter
provided with the scraper or discharger, and it therefore results that the impurities
from the raw sugar are concentrated in a comparatively small quantity of bone
black; that is, the exhausted bone black which is removed, from time to time or
continuously, by the operation of the discharging instrumentality.
By means of the improved apparatus forming part of the present invention
provision is made for carrying on a continuous decolorizing operation, in which all
the sugar liquor which is forced through the filtering chamber is subjected to
uniform conditions with respect to the duration of its contact with a fixed quantity
of bone black, the decolorizing power of which is maintained substantially
unchanged by the gradual removal of the exhausted bone black and collected
impurities from the bottom of the filtering chamber and the concurrent feeding of
fresh bone black, to the top of the filtering chamber.
In its essential features the apparatus consists of First; a filtering chamber into
the top of which the fresh bone black is fed as required; Secondly, of a supporter
and discharger or scraper, for supporting the column of bone black contained in the
filtering chamber and for effecting at a prescribed rate the gradual removal of bone
black from the base of the column as the bone black at that point becomes exhausted
and charged with impurities separated from the sugar liquor, which enters the
filtering chamber at the bottom; thirdly, of a receiving chamber beneath the
filtering chamber for receiving the exhausted bone black and collected impurities
discharged from the filtering chamber; fourthly of means for removing the exhausted

page_text: bone black and collected impurities from the receiving chamber; and, finally, of a
conduit for introducing into the receiving chamber, under suitable pressure, the
sugar liquor which is to be decolorized, and an outlet or outlets for the discharge
from the upper part of the filtering chamber of the sugar liquor which has been
forced upward through so much of the column of bone black as is below the level
of the said outlet or outlets.
The supporter and discharger constitutes the movable bottom of the filtering
chamber, and is a diaphragm provided with perforations or slots of such shape and
dimensions that while they will not permit the superincumbent bone black to fall
through them continuously under the influence merely of its own gravity, they
will serve, when the diaphragm is appropriately moved, to effect the removal and
discharge from the base of the column of a stratum of bone black of prescribed
thickness.
In the accompanying drawing illustrating the said improved apparatus,
Figure 1 is a central vertical section of the filtering chamber, the receiving
chamber, and other appurtenances of the apparatus.
Figure 2 is a horizontal section taken through the line on Figure 1, affording
a top view of the movable diaphragm which constitutes the movable bottom of the
filtering chamber, and which by reason of its functions is herein called the supporter
and discharger or scraper.
.
Figure 3 is a vertical section of the scraper taken through the line y, y on.
Figure 2.
The apparatus represented in the drawing consists, substantially, of a vertical
cylinder A for containing a column of bone black B; a movable slotted diaphragm
or scraper C; and a receiving chamber D having an inclined bottom D¹, by means
of which the exhausted bone black and impurities removed by the scraper are
conducted by their own gravity into the bottom of the well E, from which they
o are elevated by means of the bucket and chain elevator E¹ and discharged at the
mouth of the well upon the inclined chute E.
The saccharine liquor to be decolorized is introduced into the well by means of
the pipe F, from a suitably elevated reservoir. The sugar liquor thus introduced
falls into the bottom of the well, and rises by hydrostatic pressure through the
mass of bone black B contained in the filtering chamber, and escapes therefrom,
through the perforations G in the side wall of the cylinder A, into the external
trough G¹, from which it is conducted. to a suitable depository by the discharge
pipe G'.
The scraper C is circular and is of larger diameter than the cylinder A, so that
its rim C¹ is contained within the circumferential enlargement A¹ of the cylinder A.
The face of its rim is grooved and provided with suitable teeth for engagement by
the driving worm H, by means of which the scraper is rotated upon its central
vertical axis. The hub of the scraper is provided upon its under side with the
trunnion I, which is journalled in the box I¹ arranged upon a beam fixed horizon-
tally across the receiving chamber, and having its central portion i supported by ·
the inclined braces 12 and I³.
The scraper is provided with radially slotted openings C*, C*, &c. The upper
edges c and c¹ of the side walls of each of the slots C form, respectively, the one
an acute and the other an obtuse angle with the upper surface of the diaphragm,
substantially as shown in Figure 3. The acute edge c is the cutting edge, and
being somewhat higher than the obtuse edge c', operates, when the scraper is
rotated, to cut away from the base of the column of bone black a helical chip or
shaving of uniform thickness, which falls down the inclined bottom D¹ of the
receiving chamber D to the bottom of the well E, and is caught and carried upward
by the buckets e, e &c.
The buckets ee &c, are made of wire gauze, or are finely perforated, and the
well tube is prolonged considerably above the level of the mouth of the inlet
pipe F, in order that the sugar liquor may have an opportunity to drain out of the

page_text: buckets during the latter part of their upward journey before they discharge their
contents upon the chute.
+
Having now particularly described and ascertained the nature of the said
invention 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
-
First. The herein described process of removing the impurities from raw sugar,
the same consisting in dissolving the raw sugar in water and then filtering it by
forcing it upward through bone black; and, by means of a scraper or discharger,
gradually removing the collected impurities and exhausted. bone black from the
bottom of the mass of bone black contained in the filtering chamber through which
the sugar liquor is forced.
Second. In apparatus for effecting the decolorization of sugar liquor by the
process of upward filtration through bone black; the combination as herein set
forth of a filtering chamber, having a movable bottom for supporting the column
of bone black contained in the filtering chamber and for gradually removing the
bone black from the bottom of said column; a receiving chamber for receiving the
bone black so removed from the filtering chamber; and' means for removing
the bone black from the receiving chamber without interrupting the upward flow
of the sugar liquor through the column of bone black to outlets provided for its
exit from the filtering chamber.
نم
1007
HASELTINE, LAKE & Co.,
For the Applicant.