An Improved Process for the Manufacture of Sugar.
Year: 1895

page_text: Date of Application, 7th Aug., 1895-Accepted, 28th Sept.. 1895
COMPLETE SPECIFICATION.
An Improved Process for the Manufacture of Sugar.
1. GEORG KASSNER, of 15 Nord-Strasse, Munster, Westfalia, in the Empire
of Germany, Professor, 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 :---
The best process that has been employed hitherto for extracting cane sugar from
sacchariferous solutions in the condition of a compound dissolving with difficulty,
is unquestionably that which consists in turning to account the property which
is possessed by hydrated barium and hydrated strontium of combining with cane
sugar.
This method of utilizing the oxide of alkaline earths is however attended with
three somewhat serious drawbacks which reside in the very nature of the chemical
agents named, and therefore may be neither obviated nor prevented; viz.:
(1) That the hydrates of strontium and barium will only separate cane sugar, or
"raffinose," but have a destructive action upon the various kinds of glucose, so
that the extraction and separation, for manufacturing or commercial purposes, of
glucose, on the one hand, and of cane sugar, on the other, as well as the extraction
of the soluble salts contained in the juices of plants, become impracticable;
(2) That the strontium or barium saccharates are by far too readily soluble to
admit of the foreign salts and colouring agents being separated therefrom by
lixiviation; and
(3) That the process of regeneration of the hydrates of alkaline earths from the
carbonates formed in the saturation stage requires too high temperatures for its
performance, thereby adding very considerably to the cost of the fuel consumed,
while the furnaces which have to be used in carrying it out are liable to speedy
destruction.
Now the process forming the subject of this invention is free from the defects
above enumerated. It involves the employment of oxide of lead as a separating
agent, and is based upon the fact (which is well known to scientists) that it yields
combinations of sugar and lead, which are only soluble with difficulty:
This, as stated, was merely a scientific discovery, as was also the circumstance
which was first pointed out by Dubrunfant-that lead-saccharate forms under the
influence of cold, and that it does so gradually, when hithargyrum is allowed to
stand at rest together with a pure solution of sugar. These scientific data, taken
y themselves, were of no practical value and totally unfit to render any service to the
ade, lacking as they did various features essential to success. And, in truth, it has
theito occurred to no one to attempt to render Dubrumfaut's discovery serviceable
or the trade or market, for extracting sugar from molasses or from any mixture
embodying foreign or impure substances, much less for separating the several kinds
of sugar from each other; all this having been impracticable for want of experience,
nd because the behaviour of oxide of lead, in the different cases alluded to, was
nknown. The applicant, therefore, has assumed the task of ascertaining the
equiements to be fulfilled, which, not having been known before, might not be
omplied with.
The applicant, after numerous trials, partly unsuccessful-has at length succeeded
n devising a really serviceable process, and, what is better still, in imparting to it
he character of a contit uous circular process (or what is sometimes called a "cycle")
herein all the materials or agents employed are brought back to their starting
vints after having performed their respective duties.

page_text: The most important conditions upon which the successful performance of the
process depends are as follows:
(a) The oxide of lead employed should be in the form of a powder which must
be as fine and as uniform as possible;
(b) Between the oxide of lead and the sugar there should be a predetermined
relation of weight, especially when the process is carried on on rational lines, that
is to say, for manufacturing or commercial purposes:
(c) For the purpose of separating the saccharate rapidly and in an even and
uniform manner the action of heat should be brought into requisition.
(d) The concentration of the solutions should be so proportioned that the
resulting combination of oxide of lead with the sugar can be but slowly precipitated
at the bottom of the vessel;
(e) Care should be taken to ensure as close and as uniform a contact as possible
between the heavy insoluble oxide of lead and the solution of sugar. This may be
done. for example, by keeping the mixture in violent motion or briskly stirring it
until the saccharate begins to form ;
(f) The separation of the saccharates should be so conducted that the various
sorts of sugar may be collected separately. This last mentioned result will be
obtained by taking advantage of a fact which the applicant has also had occasion
to ascertain in the course of his labours, namely, that where a mixture of various
species of sugar is dealt with, the oxide of lead will cause the glucose in its various
forms to be precipitated first, while the cane sugar will not precipitate until after-
wards. Attention should also be paid to the desideratum of obtaining the saccharate
of cane sugar in the condition of agglomerated lunips having the shape of small
balls or worts and consisting of radially disposed fine needle-shaped crystals,
inasmuch as it will be found that these spherical crystals are capable of being more
readily washed out or extracted by lixiviation than would be the case if the
saccharate was in a different form.
Another observation of which advantage is taken in the performance of this
process is that the non-sacchiferous substances which may be present in the
vegetable juices (more particularly those possessing the characteristics of acids)
directly they have been precipitated together with the sugar in the condition of a
non-soluble compound of lead, in the subsequent saturation stage do not, (or to a
very slight extent, if at all) become decomposed simultaneously with the saccharate.
As a rule, the saccharate is not separated until the non-sacchiferous substance (if
they be separated at all) reach the separation stage in their turn, so that as a result
of this fact also the separation or extraction and the purification of the sugar are
rendered feasible.
Most of these observations are entirely novel, and by putting them to practical
use, the improved process which forms the subject of this invention is carried out
somewhat on the following lines:
Oxide of lead or hydrated oxide of lead, or mixtures containing oxide of lead,
either hydrated or not and either in a complete or in a nascent form, are triturated
with water and uniformly stirred until they form a thin semi-liquid mass. Among
such mixtures equivalent to oxide of lead and therefore fit to be used as substitutes
therefor, combinations or compounds of lead salts with caustic alkalis or alkaline
earths, and also the plumbites or the like of such alkalis and alkaline earths, may
be mentioned by way of example. After this trituration stage, the sacchariferous
solution (such as a solution of molasses, beetroot juice, or the like) which is to be
precipitated, and which has preferably been freed beforehand from such substances
as will precipitate under the action of milk of lime (lime water) or by lead-vinegar,
are added while being kept in a continual state of agitation by stirring. The
stirring should be so vigorous and the concentration of the sacchariferous juices
should be so high that the oxide of lead may not readily go down to the bottom.
Its descent must in fact be uniform in all parts of the mixture inasmuch as it is
most important for the purposes of sugar extraction and purification that there
should be formed in as many points as possible centres of crystallisation lest the

page_text: proper relation or proportion of the respective atomic weights of lead and sugar
should be disturbed while the oxide of lead is collecting at the bottom. For if
that precaution were not taken the oxide of lead might by being covered over with
insoluble crystal lumps of agglomerations or by becoming itself "baked" into a
lump, be withheld from the proper reaction, with the result that the precipitation
of sugar would be, technically speaking, incomplete.
Or the intimate contact of the sacchiferous solution with the oxide of lead which
is such an indispensable condition for the formation and separation of the saccharate,
may to a certain extent be brought about by causing the sacchariferous liquids to
filter through a suitable number of layers of oxide of lead, say, on the principle of
inverse or counter currents. It is, however, most important that in producing the
mixture directly by stirring, a well defined relation should be maintained between
the oxide of lead and sugar inasmuch as, if the proportion of lead should be too
small, the sugar would remain unseparated, while on the other hand, too liberal an
amount of lead would unduly add to the difficulty of lixiviation, and necessitate
the consumption of too large a quantity of carbonic acid in the subsequent
separation stage. The proper proportion, for example, may be to every one
molecule of cane sugar, a little over two molecules of oxide of lead, and to every
one molecule of "dextrose" or "inverted" sugar, say, from about 1 to 2 molecules
of oxide of lead. While stirring the mixture to make it thorough it should be
slowly heated. Under the joint influence of these several factors, a chemical
combination or "binding" action will in a short time set in, the mixture beginning
to solidify when this point is about to be reached. The stirring is then
discontinued, for at that period of the operation whatever oxide of lead has not
been absorbed in the combination will of its own accord remain in suspension.
The mass under treatment is then allowed to stand at rest in order to afford the
saccharate an opportunity of crystallising out.
Where it is desired to separate the various sorts of glucose from the cane sugar,
there should only be used in the first instance just as much oxide of lead as the
glucoses are capable of binding in the form of insoluble saccharates. After this
the cane sugar (or any other polysaccharides there may be) may be separated in a
filtrate.
The compound of sugar and lead (e.g. a combination of cane sugar and lead, a
combination of glucose and lead, and one of inverted sugar and lead, or the like, or
the mixtures of these combinations) obtained in the manner above described, may
be freed from the parts which have remained in a liquid state, or which are soluble
in water, by removing them by means of suitable (filtering) presses, by suction or
by centrifugal action, and then by either washing them with water, or submitting
them to the dialytic or "diffusion" process. The liquid separated in the first
instance and not yet diluted with water, in the treatment of molasses forms a
valuable (because comparatively concentrated) solution of salt with which little or
no sugar is mixed. But should it be desired to obtain even these slight admixtures
of sugar, if any, the salt solution need only be treated with further quantities of
oxide of lead which will lead to the extraction of the last remnants of sugar just
referred to.
The saccharate having been carefully washed or lixiviated, when it is capable of
any amount of further purification, will dissolve but with great difficulty, the
applicant has found, indeed, that in the case of compounds of cane sugar and lead,
the relation is as 1 to 11,000 parts of water. This saccharate, then, is triturated
and treated with carbonic acid or gases containing carbonic acid (the saturation
gases) until it is entirely decomposed.
There forms an insoluble, mostly basic carbonate of lead (white lead) and free.
sugar, the solution of which is separated from the salt of lead by filtration or the
like and then further treated with a view to obtaining a marketable product. The
lead is eliminated in toto by this process, so that not the slightest trace of it will be
found in a carefully filtered sugar solution. Besides a reliable means of tracing
the presence of and expelling any remnants of lead is afforded by sulphuretted

page_text: hydrogen and the corresponding sulphur compounds-if it should happen that the
operation has not been conducted with sufficient care to eliminate the lead in the
first instance. The muddy deposit resulting from saturation, from which the sugar
has been extracted, mainly consists of basic carbonate of lead. This is then
introduced into regenerating furnaces in which by being slowly heated it is
reconverted into oxide of lead. By keeping the air out during the first heating
stage and, if desired, by conducting a current of steam through the material
heated, there will only be obtained, in the first instance, pure i.e. concentrated
carbonic acid which will return to its proper place in the cycle of operations.
After expelling the carbonic acid air may be admitted to the charge under
treatment, the oxygen of which air will assist the regenerating action of the oxide
of lead while the organic admixtures of lead (the non-sacchariferous substances) will
be entirely burnt.
The advantage which the employment of the sugar extracting process above
described offers over all other existing processes resides in the fact that the
carbonic acid contained in the mud collected in the saturation stage may be
readily recovered in a high degree of concentration, seeing that basic carbonate of
lead will decompose at temperatures not exceeding 250° Centigrade or thereabouts.
Thus not only is the heat required for regeneration very moderate; not only are
the furnaces or retorts protected from rapid destruction (they may be made of
iron); but above all very high highly concentrated carbonic acid is obtained,
which returns to its place in the cycle of operations, a result which it has not
been possible to obtain in any of the extracting processes hitherto known.
Superficial observers might raise this objection to the process herein described,
that in its performance a poisonous substance is made use of, and that consequently
the risk of incompletely separating it from the product of daily consumption would
always remain attached to it. But this is a difficulty which the present state of
industry enables to be very readily disposed of; for it is one of the triumphs of
modern science that it permits the most noxious or dangerous substances to be
handled with the greatest case and with a perfect avoidance of any danger being
involved in the use or consumption of the final product.
Nothing, indeed, is easier than the entire elimination of any lead there may be
still contained in the aqueous solutions. Such lead may as a matter of fact be
separated with far greater facility than the (also poisonous) baryta which as is
well-known, is an important factor in the sugar extracting process known as the
'baryta saccharification" process. Besides, as before stated, sulphuretted
hydrogen forms an excellent means for testing the product as to its absolute
freedom from lead, a means which will be as readily available to the manufacturer
as to the authorities and, indeed, to the consumers themselves.
66
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 employment of oxide of lead, hydrate of lead, or mixtures containing
these bodies either originally or as a result of chemical treatment, such, for
example, as combinations of salts of lead with caustic alkalis, or alkaline earths,
plumbites of alkalies or alkaline earths or the like, for the separation extraction
and manufacture on a large scale (for the trade or market) of various sorts of
sugar from aqueous solutions still containing an admixture of foreign bodies; such
solutions being, for example, the juice of certain plants, beetroot juice, molasses,
the juice or liquor obtained from the treatment of sugar cane, from sorghum, maple
juice or the like.
2. In carrying out the process referred to in the first claim, thoroughly mixing
the oxide of lead or hydrated oxide of lead with the sacchariferous liquor, or
adding it to such liquor in a state of suspension; separating the saccharate
obtained from the soluble bodies (salts or the like) and then decomposing it by
means of carbonic acid or gases containing carbonic acid; it being optional, if

page_text: preferred, to substitute for the mixing or suspending process, an operation
consisting in allowing the sacchariferous liquors to filter through a suitable
number of layers of oxide of lead or hydrated oxide of lead.
3. In carrying out the process covered by the first claim, regenerating the oxide
of lead from the mud obtained in the saturation stage, by treating the same with
carbonic acid, or carbonic acid gas, the carbonic acid being if necessary recovered
by heating the saturation mud with or without the admission of a current of air or
steam.
Dated this 7th day of August 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.