IMPROVEMENTS IN THE PURIFICATION OF THE JUICES, SYRUPS, AND MOLASSES FROM BEET-ROOT AND SUGAR CANE
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Charles Denton Abel at the Office of
the Commissioners of Patents on the 6th December 1880. A communication
from abroad by Auguste Pierre Dubrunfaut, of Paris, France, Manufacturing
Chemist.
«
CHARLES DENTON ABEL, of No. 28, Southampton Buildings, Chancery Lane, in
the County of Middlesex. "IMPROVEMENTS IN THE PURIFICATION OF THE JUICES,
SYRUPS, AND MOLASSES FROM BEET-ROOT AND SUGAR CANE." [A communication
from abroad by Auguste Pierre Dubrunfaut, of Paris, France, Manufacturing
Chemist.]
It has been found that the impure syrups or juices of beet-root heated or boiled
with lime are subject to changes, giving rise to the formation of salts of lime;
these salts come from two sources, namely, first, from the reaction of the alkaline
earth on the organic matter of the syrups, and, second, from a similar reaction
upon the organic salts. In both cases soluble or insoluble salts of lime are
formed.
"
It has also been observed that in carrying out the system of purification termed
the "calco-carbonic process the soluble salts of organic acids (that is, salts on
which there is no osmose action) are eliminated, at least partially, in a single
operation.
It has furthermore been observed that the osmose process applied at raised
temperatures to syrups strongly alkalised with lime completes the transformation
which has been produced by the boiling with lime, so that this mode of operating
realises with the greatest perfection the osmosic purification which eliminates the
mineral salts with occlusion of the sugar at the same time that it generates in the
syrups the greatest proportion of the calcic salts which it is the object of the calco-
carbonic purification (which follows this process) to eliminate.
These diverse processes more or less known and badly carried out at present can,
by being coordinated systematically, furnish all the elements useful for the solution,
at least partial, of a problem often proposed but never solved, namely, the manufac-
ture of beet sugar without residue of molasses.
These processes carried out as will now be described, have the great advantage of
being exceedingly simple, easily applicable in all manufactories, and to all systems
of manufacture.

page_text: for plant or cost or manufacture.
In specifying the various modes of application I will begin with the most simple,
that is to say, the process most generally used.
RASPING AND PRESSING PROCESS.
In order to apply the new process the usual normal process of defecation (which
is in reality only an imperfect carrying out of the calco-carbonic process) is carried
on for some days. In this case it is useful to alkalise slightly with lime the waters
thrown on the rasp, or those which serve for the second pressing when mechanical
presses are used. The lime used in this case has for its object to transform the
pectine of the pulp or pectate and the albumen into insoluble compounds. The
products of this process maintained slightly alkaline, and either filtered or not
through granular animal charcoal, are boiled, crystallised, and subjected. to
centrifugal action as usual. After some days of operating, that is to say, as soon
as by the centrifugal action on the primary sugars the discharge liquor therefrom
has been rendered available, the processes which constitute the present improve-
ments are carried out. The discharged syrup, mixed moderately with milk of lime,
is heated to a temperature which may vary from 60° to 100° centigrade, according
to the requirements of the process; it is then subjected to the hot osmose process.
In most cases it is sufficient to produce a moderate osmose action, that is to say, to
reduce the density of the syrup to 25° Beaumé. This simple operation already
realises the useful effect afforded by the calcic ebullition; and this effect, which is
continued during the entire duration of the osmose action, shows its intensity and
utility by the alkaline character which it imparts to the liquor of exosmose, which
character is due exclusively to the soluble caustic alkalies (potass and soda) derived
from the organic salts of the syrups. Under these circumstances the osmosised
syrup which comes out at a temperature of from 50° to 80° cent. is mixed with the
cold juices from the presses, which readily reduce the temperature to 30° or
35° cent., at the same time that the density of the juices is raised to from 10° to
12° Beaumé, which conditions are exclusively the most perfect for usefully carrying
out the calco-carbonic process. This mixture is saturated with lime, and introduced
into the boiler for defecating by agitation, where it must be methodically subjected
to gaseous action, the following being the best mode of operating:-The syrup is
subjected to the gaseous action in a cold condition (at about 25° to 30° cent.),
employing the usual precautions for preventing frothing, and the operation is a
stopped when the syrup shows a decided tendency to thicken, without attaining an
actual solid consistency. This point is important in the operation, because upon it
depends the greater or less elimination of the organic calcic salts, that is to say, the
purification effected by the calco-carbonic process. This purification is the only
useful object of the defecation by agitation, as ordinarily carried out. In this case,
in effect, the phenomena of thickening can never be obtained, which requires a
density of the mass of at least 10° to 12° Beaumé; also the purifying effect of the
defecation by agitation is very variable and uncertain in the various manufactories.
It can be practically ascertained whether the gasified syrup approaches the
thickening stage by its very opaque appearance; it may be still better determined
by heating small samples to 100° centigrade, when if the syrup is at the desired
point of density it will solidify. If this operation is well carried out it should
effect the elimination of at least from one half to two thirds of the salts of lime by
one operation, which is readily ascertained by means of the hydrotimeter. When
the above treatment has been brought to the desired point, ascertained by the means
above set forth, the supply of gas is stopped, and the mass is heated to boiling
point; this operation clarifies the syrup, which when at rest gives an abundant
heavy deposit, readily separated by the filtering presses. The syrup, which is very
alkaline, is decanted and placed in the boiler for double carbonisation, where it is
saturated with carbonic acid gas while hot. If this process is efficiently carried out

page_text: PROCES
This process, which is becoming general in sugar mills, offers no obstacle to the
application of the new processes; on the contrary, the more complete exhaustion of
the residues resulting in a greater yield of molasses, there is on this account a
greater need for the application of such processes which are essentially for the
purification of the molasses. The process will besides require but slight changes in
its application. Thus the calcic discharge liquors osmosised, nearly pure and hot
or even boiling may with advantage be put together with the beet-root, cut in
slices or pieces, in order to raise their temperature to that which is useful for
diffusion, and this operation may with advantage be effected in the diffusers them-
selves. Under these conditions besides the heating, of the roots and the cooling of
the syrup an osmotic exchange will be effected between the two products, that is
to say, the syrup will become richer in sugar and poorer in salts at the same time
that it will become diluted while the roots will be affected in the opposite manner.
Lastly, when the circulation of the syrup over the roots will have reduced its
density to from 10° to 12° Beaumé, at the same time that the temperature will have
been reduced to 20° to 25° cent., it is removed for proceeding to the defecating
process.
On the one hand the roots of which the juice will have increased in density
through its diffusion with the discharge syrup will be exhausted by the ordinary
processes, that is to say, by means of water, and the syrup at the head of the
diffuser having attained the maximum density will be transported to the defecating
boiler with the discharge from the first operation. There the two syrups, having a
mean density of 10° to 12° Beaumé and a temperature of 30° to 40° cent., are
saturated with lime in order to be subjected to the calco-carbonic purification,
precisely in the same manner as described in the first process. The roots coming
from this operation will retain with greater certainty the pectic products in the
form of pectates and the albuminous products, as their contact with the discharge
syrups facilitates the reaction that produces this effect.
OPERATION WITH MOLASSES AND SYRUP.
All products to which the osmotic purification is applied are susceptible of being
subjected to the new processes, on condition that they do not contain large propor-
tions of glucose. These syrups calcified in the heating boiler as previously described
for the discharge from the first extraction may be perfectly subjected to the hot
calcic osmose action, and there they realise the useful effects for transforming the

page_text: diverse impurities into calcic salts. In the case under consideration, that is to say,
for products much more impure than the discharge from the first extraction, the
osmose action should be thorough, that is, from 10° to 12° Beaumé.
To prevent the inconveniences of too hot a calcic osmose action cold or luke warm
water may be used so that the osmose action may be effected at from 50° to 70° cent.
The osmosed syrups are cooled by any known means to from 35° to 40° cent., are
saturated with lime and subjected to the calco-carbonic purification, such as has
been previously described.
Good molasses subjected to this purifying process, which might if necessary be
repeated, as calco-carbonic treatment with feeble osmose action followed by filtra-
tion on a thick layer of granular charcoal will without fail be capable of subjection
to the process of boiling for granulation. And it is to be observed that this mode of
operating destroys the compound of sugar and alkali, which has been found to be the
main cause of the double saccharimetric character of the calcic syrups and molasses.
This effect is produced by the elimination by means of hot calcic osmose action of the
caustic alkali which characterises the uncrystallisable sugar having the double
character, and the uncrystallisable sugar in regaining its normal constitution at the
same time becomes crystallisable, which constitutes a new and important purification,
due entirely to the novel process of hot calcic osmose action.
It has also been found by experiment that this process is applicable to all products
containing more or less glucose derived from beet or from sugar cane, either at the
sugar mills or the refineries.
It has been considered necessary to except those products of this kind that
contain large quantities of glucose, as in treating these in the hot state with lime
a glucate of lime is formed as the initial product of the reaction, which is soluble
and indifusible, and resists the method of calco-carbonic purification.
It has been observed that when the alkaline reaction is prolonged so as to transfer
all the glucose into apoglucic acid, and consequently into apoglucate of lime, this
salt undergoes complete elimination by the calco-carbonic purification. Con-
sequently all syrups and molasses of beet-root subjected to the new processes
undergo the purification above mentioned and lead to the preparation of syrups
with these products purified to such a degree that they can be subjected to the
process of boiling for granulation, and yield white sugars differing little in quality
from the sugars of first extraction.
It will be readily understood that under these conditions the new processes are
also applicable in refineries even where sugar cane is operated upon, as also in sugar
mills operating with sugar cane.
The glucosic products require an addition of lime such as will bring to the trans-
formation into apoglucate the glucose combined with the products to be operated
upon. Caustic soda and potash, in effecting the transformation in question more
rapidly, can be utilised for the products of a very glucosic nature, such as those of
the sugar mills and refineries for cane sugar.
The high colouring produced in the syrups by this transformation does not
matter, as these products, transformed into salts of lime by the calcic osmose action,
being eliminated by the calco-carbonic purification give syrups of only slight
coloration on which animal charcoal has a considerable action. Thus in England
where large quantities of animal charcoal are employed for decolorising, the use of
the new processes will reduce this quantity to a minimum.