Improvements in and relating to the Manufacture of Refined Sugar from Raw Sugar.
Year: 1892

page_text: Date of Application. 23rd Mar., 1892
Complete Specification Left, 20th Dec., 1892-Accepted, 4th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in and relating to the Manufacture of Refined Sugar
from Raw Sugar.
I, THEODOR DROST, of 8. Gartenstrasse, Breslau in the Empire of Germany,
Merchant, do hereby declare the nature of this invention to be as follows:-
All hitherto known refining processes have, I believe, for their object to divide
up the raw sugar, which is to be refined, in such a way that, on the one hand, only
the pure crystals contained in the raw sugar are obtained, and, on the other hand,
only the green syrup adherent to the raw sugar crystals. Stated in figures: raw
sugar of, for instance, 95 polarisation such as usually handled in commerce, when
refined has in 100 parts of sugar 87-19 pure sugar and 12-81 green syrup with an
approximate purity quotient of 72.
Doubtless such a process would have hitherto been regarded as unattainable by
which the sugar could be decomposed in such a way that, as a matter of fact,
87-19 per cent. of pure crystals and 12.81 per cent, green syrup with a quotient of 72
could be produced in a very short time and with the existing factory arrangements.
At present the purification of raw sugar is effected as a rule by one of two methods,
either, first, by a process where steam is introduced into the rotating centrifugal
containing the sugar crystal mass to be cleansed, or else, secondly, by a process
where the sugar crystals are cleansed in the centrifugal by means of an absolutely
pure colourless solution of sugar. These processes, in practice, yield the following
figures:
1) In the first process, by means of which crystal or block sugar is produced
from raw sugar, for instance, from 100 kilogrammes of raw sugar of 95 polarisation,
to which adheres a syrup of 72 quotient of purity, there are obtained, in favourable
cases, 74 kilogramnies of crystal sugar or 71 kilogrammes of block sugar, and
therefore, as in the 100 kilogrammes of raw sugar of 95 polarisation there were
contained 87.19 kilogrammes of pure crystals, there are dissolved 13.19 kilogrammes
of pure 100 per cent. sugar in manufacturing crystallised sugar, and 16.19 kilo-
grammes in manufacturing block sugar.
2) In the second named process by means of an absolutely pure_colourless
solution of sugar, which only allows crystal sugar exclusively to be produced from
the raw sugar, about 25 kilogrammes of pure sugar, which, when dissolved, yields
about 35 kilogrammes of the sugar solution, must be used for purifying 100 kilo-
grammes of raw sugar. By this process, the whole of the pure sugar crystals
are indeed obtained without loss from the raw sugar, but the whole of the solution
employed for clarifying is rendered impure by the syrupy constituents of the
raw sugar.
Both processes have, therefore, the great disadvantage in common that a
considerable quantity of white sugar must be employed for the purification, which,
being considerably deteriorated by the green syrup of the raw sugar, forms the
residue, which yields, in the further course of the treatment, sugar products of less
value.
This drawback is removed by this improved process of purificatiou, in such a way
that the raw sugar is divided, without loss, into pure crystals and green syrup, and
the residual products may be again favourably introduced into the process without
any further treatment.
Raw sugar is mashed with green syrup, of about 70 to 72 quotient of purity from
a previous working, to a sugar paste resembling a filling mass ("masse cuite"), in
doing which, it should be noted that the green syrup employed for mashing may

page_text: preferably be diluted by the addition of water to about 1.33 specific gravity,
68-70 Ballg.
The green syrup adhering to the raw sugar crystals is thereby somewhat liquefied
and is more easily centrifugaled out. The raw sugar mashed with green syrup
is then introduced into the centrifugal, and, at the commencement of the
centrifugaling, steam is introduced between the case and drum in order, on the
one hand, to assist in the removal of the syrup by means of warming the drum
and side of the case, and, on the other hand, to constantly moisten and keep clean
the inner wall of the case, and thus to facilitate the running away of the syrup
thrown against it by the centrifugaling.
The whole of the mash syrup and the greater part of the green syrup liquefied
but still adhering to the raw sugar are thrown off by the rapid rotation of
the centrifugal, so that a raw sugar of about 97-98 polarisation remains in the
centrifugal.
By this first operation, almost the whole of the green syrup from the raw sugar,
which forms the worst product of the sugar which is to be purified, is entirely
removed from the process, and this syrup forms, as will be hereinafter shown, the
first and sole refuse product of the process which may be treated further in
the usual manner, or, as already stated, may be employed for mashing fresh raw sugar.
Then the actual clarifying process is proceeded with. The clarifying liquid,
employed for this clarifying, is indeed a clear but more or less brown or yellow
coloured solution of raw sugar, which, for a better action, is filtered, before being
used, through bag filters or carbon filters, and possesses a specific weight of 1.325
(66-68 Ballg.).
The raw sugar remaining in the centrifugal is now treated with this clarifying
liquid, which possesses, at least, a degree of purity of 95, whilst the syrup to be
driven off possesses one of 72, and, for each. 100 kilogrammes of raw sugar
treated, about 12-14 kilogrammes of clarifying liquid are employed. After this
clarifying, the sugar is almost white, and has a polarisation of at least 99.2 to 99.8.
In order to economise the clarifying liquid especially for cheap kinds of sugar,
as well as for first or after products having a low percentage of sugar, the
sugar to be treated may be subjected to a preliminary treatment before the
clarifying process above described, in order to render easier the removal of
the particles of sugar firmly adhering to the sugar crystals of the dry sugar,
consists in dissolving the sugar and working the same into a "masse cuite" in
the usual known manner, and then subjecting this "masse cuite," mashed as
described for sugar, or unmashed (the latter is quite possible by reason of this
preliminary treatment) to the clarifying process above described.
which
By this means, half the time and half the clarifying material may be economised.
In consequence of this mode of preliminary treating the sugar, which is to be
clarified, in which the latter is dissolved into thick syrup and then boiled to a
masse cuite," it is possible to employ a raw sugar solution brought by suitable
concentration to correspond to a specific: gravity of about 1.325; to replace this
process.
The solution may also be prepared from, the "masse cuite." or from sugar without
boiling down, equal to about 1-325-specific gravity, and, if necessary, any impurities
may be removed by filtration.
In some cases, such for instance as where a special vacuum apparatus is not
available for concentrating the clarifying liquid, clarifying liquid of the before
mentioned various kinds and even of a degree of concentration, which has not
attained the one mentioned, may be used for the clarifying process; in that case,
the clarifying liquid will receive in the centrifugal itself the requisite strength by
means of the syrup still adherent to the sugar crystals, or even by small quantities
of the sugar itself which is to be clarified.
With this clarifying operation, the second section of the work is thus ended,
namely, the clarifying or purifying with clarifying liquid..
It is evident that, in consequence of the concentration of the clarifying, liquid, no

page_text: dissolving of the sugar crystals can take place, so that all the sugar is obtained
with a polarisation of 99.2 to 99-8. Then the third operation commences, namely,
the employment of steam in the centrifugal of 1 to 2 minutes duration, which has
for its object, on the one hand, to convert the sugar in the centrifugal of 99.2 to
998 per cent. into sugar of 100 per cent. or marketable goods, and, on the other
hand, to dry the sugar or in the case of cube sugar to complete the finishing of the
same.
By this employment of steam, 1 to 1 per rent. of pure sugar is indeed dissolved,
but this solution of sugar is added to the clarifying syrup thrown out by the
previous process.
As then the first refuse liquor from the clarifying process has lost about 3 per
cent. of its purity through the particles of syrup contained therein, but is again
brought almost to its original degree of purity by the subsequent addition of the
almost 100 per cent. solution resulting from the last described employment of steam
for finishing the clarifying process, it is evident that this residue may be conveyed
without further treatment to the vacuum apparatus and there treated in the usual
manner simultaneously with other liquids which are to be boiled down there.
The same may be added to the process before the filtration, or if preferred may
be employed by itself alone for a fresh clarifying. In this case also, when expressed
in figures, there are obtained first by this new process, from 100 kilogrammes of raw
sugar of 95 polarisation, with the thereto adherent green syrup of 72 quotient of
purity and which raw sugar consists of 87.19 kilogrammes pure sugar and 12.81 kilo-
grammes of green syrup, after the first operation-a raw sugar of about 97-98
polarisation. As raw sugar of 98 polarisation only contains 5.13 syrup, there is
removed by the first operation with the mash syrup which is thrown off also
12-81-5.137.68 kilogrammes of green syrup,
By the subsequent clarifying, the whole of the syrup down to imperceptibly
small quantities is centrifugaled out of the raw sugar, that is to say, from the
remaining 13 parts, at least 5 are removed, and there then remains the whole of
the pure sugar contained in the raw sugar plus the still remaining 0.13 parts of
syrup, consequently 87.19 +0.13 = 87.32 sugar of at least 99's polarisation in the
centrifugal. By the employment of steam, almost 1 to 14 per cent. of sugar is
dissolved, thus, by this process, there are obtained at least 855 kilogrammes of
pure marketable sugar at the first throw, which makes approximately 992 per cent.
of the total pure sugar contained in the raw sugar.
It will be unnecessary to here remark that the sugar dissolved by the steam is of
course not lost, but immediately after the boiling down of the residue is recovered
as raw sugar, which, together with fresh raw sugar, is converted again into marketable
sugar. By the above described process, therefore, on the one hand, all the
crystallisable sugar is actually obtained as marketable goods, whilst, on the other
hand, only a single residual product, namely the green syrup, remains, which always
retains its original purity, as the same was separate even at the commencement of
the operation, and therefore did not come in contact either with the clarifying syrup
or with the sugar dissolved in the steam process.
The subsequent employment of steam above described may also be omitted if, for
instance, the sugar, which it is intended to produce by this process, is to be
employed in refineries for producing shaped goods, such as sugar loaves, by
dissolving this high class product, or when the same is to be brought directly into
commerce as moist marketable sugar. In such a case, it may be preferable not to
dry the same by means of the above described final process, but to obtain the same
in a still moist condition, that is, without final use of steam, as moist crystallised
sugar with 992 to 99-8 polarisation.
Dated this 22nd day of March 1892.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.

page_text: '
COMPLETE SPECIFICATION.
Improvements in and relating to the Manufacture of Refined
Sugar from Raw Sugar.
I, THEODOR DROST, of 8, Gartenstrasse, Breslau, in the Empire of Germany,
Merchant, do hereby declare the nature of this invention and in what inanner
the same is to be performed, to be particularly described and ascertained in and by
the following statement :-
All hitherto known refining processes have, I believe, for their object to divide
up the raw sugar, which is to be refined, in such a way that, on the one hand, only
the pure crystals contained in the raw sugar are obtained, and, on the other hand,
only the green syrup adherent to the raw sugar crystals. Stated in figures: raw
sugar of, for instance, 95 polarisation such as usually found in commerce, when
refined, has in 100 parts of sugar 87-19 pure sugar and 12-81 green syrup with an
approximate purity quotient of 72.
Doubtless such a process would have hitherto been regarded as unattainable by
which the sugar could be divided up in such a way that, as a matter of fact,
87-19 per cent. of pure crystals and 12.81 per cent. green syrup with a quotient of
72 could be produced in a very short time and with the existing factory
arrangements.
At present, the purification of raw sugar is effected as a rule by one of two
methods, either, first, by a process where steam is introduced into the rotating
centrifugal containing the sugar crystal mass to be cleansed, or else, secondly, by.
a process where the sugar crystals are cleansed in the centrifugal by means of an
absolutely pure colourless solution of sugar.
These processes, in practice, yield the following figures:-
1) In the first process, by means of which crystal or block sugar is produced from
raw sugar, for instance, from 100 kilogramines of raw sugar of 95 polarisation, to
which adheres a syrup of 72 quotient of purity, there are obtained, in favourable
cases, 74 kilogrammes of crystal sugar or 71 kilogrammes of block sugar, and
therefore, as in the 100 kilogrammes of raw sugar of 95 polarisation there were
contained 87-19 kilogrammes of pure crystals, there are lissolved 13-19 kilogrammes
of pure 100 per cent. sugar in manufacturing crystallised sugar, and 16-19 kilo-
grammes in manufacturing block sugar.
2) In the second named process by means of an absolutely pure colourless solution
of sugar, which only allows crystal sugar exclusively to be produced froin the raw
sugar, about 25 kilogrammes of pure sugar, which, when dissolved, yields about
35 kilogrammes of the sugar solution, must be used for purifying 100 kilogrammes
of raw sugar. By this process, the whole of the pure sugar crystals are indeed
obtained without loss from the raw sugar, but the whole of the solution employed
for clarifying is rendered impure by the syrupy constituents of the raw sugar.
Both processes have, therefore, the great disadvantage in common that a
considerable quantity of white sugar must be employed for the purification, which,
being considerably deteriorated by the green syrup of the raw sugar, forms the
residue, which yields, in the further course of the treatment, sugar products of less
value.
This drawback is removed by this improved process of purification, in such a way
that the raw sugar is divided, without loss, into pure crystals and green syrup, and
the residual products may be again favourably introduced into the process without
any further treatment.
Raw sugar is mashed with green syrup, of about 70 to 72 quotient of purity from
a previous working, to a sugar paste resembling a filling mass ("masse cuite"), in
doing which, it should be noted that the green syrup employed for mashing may
advantageously be diluted by the addition of water to about 133 specific gravity,.
68-70 Ballg.
The green syrup adhering to the raw sugar crystals is thereby somewhat liquefied

page_text: and is more easily centrifugaled out. The raw sugar mashed with green syrup is
then introduced into the centrifugal, and, at the commencement of the centrifugaling,
steam is introduced between the case and drum in order, on the one hand, to assist
in the removal of the syrup by means of warming the drum and side of the case,
and, on the other hand, to constantly moisten and keep clean the inner wall of the
casc, and thus to facilitate the running away of the syrup thrown against it by the
centrifugaling.
The whole of the mash syrup and the greater part of the green syrup liquefied
but still adhering to the raw sugar are thrown off by the rapid rotation of the
centrifugal, so that a raw sugar of about 97-98 polarisation remains in the
centrifugal.
By this first operation, almost the whole of the green syrup from the raw sugar,
which forms the worst product of the sugar which is to be purified, is entirely
removed from the process, and this syrup forms, as will be hereinafter shown, the
first and sole refuse product of the process which may be treated further in the
usual manner, or, as already stated, may be employed for mashing fresh raw sugar.
Then the actual clarifying process is proceeded with. The clarifying liquid,
employed for this clarifying, is indeed a clear but more or less brown or yellow
coloured solution of raw sugar, which, for a better action, is filtered, before being
used, through bag filters or carbon filters, and possesses a specific weight of 1-325
(66-68 Ballg.).
The raw sugar remaining in the centrifugal is now treated with this clarifying
liquid, which possesses at least a degree of purity of 95, whilst the syrup to be
driven off possesses one of 72, and, for each 100 kilogrammes of raw sugar treated,
about 12-14 kilogrammes of clarifying liquid are employed. After this clarifying,
the sugar is almost white, and has a polarisation of at least 99.2 to 99-8.
In order to economise the clarifying liquid especially for cheap kinds of sugar,
as well as for first or after products having a low percentage of sugar, the sugar to
be treated may be subjected to a preliminary treatment before the clarifying process
above described, in order to render easier the removal of the particles of sugar
firmly adhering to the sugar crystals of the dry sugar, which consists in dissolving
the sugar and working the same into a masse cuite" in the usual known manner,
and then subjecting this "masse cuite," mashed as described for sugar, or unmashed
(the latter is quite possible by reason of this preliminary treatment) to the
clarifying process above described.
half the time and half the clarifying material may be economised.
In consequence of this mode of preliminarily treating the sugar, which is to be
clarified, in which the latter is dissolved into thick syrup and then boiled to a
masse cuite," it is possible to employ a raw sugar solution brought by suitable
concentration to correspond to a specific gravity of about 1825, to replace this
process.
$6
By this means,
The solution may also be prepared from the "masse cuite
or from sugar
without boiling down, equal to about 1.325 specific gravity, and, if necessary,
any impurities may be removed by filtration.
In some cases, such for instance as where a special vacuum apparatus is not
available for concentrating the clarifying liquid, clarifying liquid of the before
mentioned various kinds and even of a degree of concentration which has not
attained the one mentioned may be used for the clarifying process; in that case,
the clarifying liquid will receive in the centrifugal itself the requisite strength
by means of the syrup still adherent to the sugar crystals, or even by small
quantities of the sugar itself which is to be clarified.
With this clarifying operation, the second section of the work is thus ended,
namely, the clarifying or purifying with clarifying liquid.
It is evident that, in consequence of the concentration of the clarifying liquid.
no dissolving of the sugar crystals can take place, so that all the sugar is obtained
with a polarisation of 99.2 to 99-8. Then the third operation commences, namely,
the employment of steam in the centrifugal of 1 to 2 minutes duration, which has

page_text: for its object, on the one hand, to convert the sugar in the centrifugal of 99.2 to
998 per cent. into sugar of 100 per cent. or marketable goods, and, on the other
hand, to dry the sugar, or, in the case of cube sugar, to complete the finishing of
the same.
By this employment of steam, 1 to 14 per cent, of pure sugar is indeed dissolved,
but this solution of sugar is added to the clarifying syrup thrown out by the
previous process.
per
As then the first refuse liquor from the clarifying process has lost about 3
cent. of its purity through the particles of syrup contained therein, but is again
brought almost to its original degree of purity by the subsequent addition of the
almost 100 per cent. solution resulting from the last described employment of steam
for finishing the clarifying process, it is evident that this residue may be conveyed
without further treatment to the vacuum apparatus and there treated in the usual
manner simultaneously with other liquids which are to be boiled down there.
The same may be added to the process before the filtration, or when advantageous
may be employed by itself alone for a fresh clarifying. In this case, also, when
expressed in figures, there are obtained first by this new process, from 100 kilo-
grammes of raw sugar of 95 polarisation, with the thereto adherent green syrup
of 72 quotient of purity and which raw sugar consists of 87.19 kilogrammes pure
sugar and 12.81 kilogrammes of green syrup, after the first operation-a raw sugar
of about 97-98 polarisation. As raw sugar of 98 polarisation only contains 5.13
syrup, there is removed by the first operation with the mash syrup which is thrown
5.13 = 768 kilogrammes of green syrup.
off also 12-81
-
By the subsequent clarifying, the whole of the syrup down to imperceptibly small
quantities is centrifugaled out of the raw sugar, that is to say, from the remaining
5.13 parts, at least 5 are removed, and there then remains the whole of the pure
sugar contained in the raw sugar plus the still remaining 0.13 parts of syrup,
consequently 87.19 + 0·13 = 87.32 sugar of at least 99.8 polarisation in the
centrifugal. By the employment of steam, almost 1 to 14 per cent. of sugar is
dissolved, thus, by this process, there are obtained at least 86-5 kilogrammes of
pure marketable sugar at the first throw, which makes approximately 99-2 per cent.
of the total pure sugar contained in the raw sugar.
as
It will be unnecessary to here remark that the sugar dissolved by the steam is of
course not lost, but immediately after the boiling down of the residue is recovered
raw sugar, which, together with fresh raw sugar, is converted again into
marketable sugar. By the above described process, therefore, on the one hand,
all the crystallisable sugar is actually obtained as marketable goods, whilst, on the
other hand, only a single residual product, namely, the green syrup, remains, which
always retains its original purity, as the same was separated even at the commence-
ment of the operation, and therefore did not come in contact either with the
clarifying syrup or with the sugar dissolved in the steam process.
The subsequent employment of steam above described may also be omitted if, for
instance, the sugar, which it is intended to produce by this process, is to be employed
in refineries for producing shaped goods, such as sugar loaves, by dissolving this
high class product, or when the same is to be brought directly into commerce as
moist marketable sugar. In such a case, it may be preferable not to dry the same
by means of the above described final process, but to obtain the same in a still
moist condition, that is, without final use of steam, as moist crystallised sugar
with 99.2 to 99-8 polarisation.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
"
1. The improvements in and relating to the manufacture of refined sugar from
raw sugar or "masse cuite on a continuous system and in centrifugals, characterised
by the following series of operations:
(a) A special centrifugaling of the mash and green syrup with a simultaneous
เ

page_text: 66
warming so as to produce a perfect separation and easy deposition of the
same, thereby avoiding any mixing with the subsequent clarifying.
(6) Clarifying with a raw sugar or sugar solution, or masse cuite" solution,
or thick syrup arising in the process, at a concentration of about 1.325 specific
gravity (66-68 degrees Blg.), or with the specified equivalent, for the
purpose of producing crystal sugar of at least 99.2 to 99-8 polarisation.
(c) Returning the refuse liquor resulting from No. & treatment into the process,
for example, into the vacuum pan for further treatment of the same with raw
sugar.
2. In the process described in Claim 1, the application of steam after the
erations a and b for the purpose of producing marketable sugar (for increasing
sugar mentioned under of 99.2 or 99-8 to sugar of 100 per cent.), and also
the purpose of simultaneously drying the same, whereby the refuse liquor, as
ntioned under 1 c, is returned preferably in combination with the refuse liquor of
operation c into the closed process.
Dated this 19th day of December 1892.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.