AN IMPROVED PROCESS FOR SEPARATING SUGAR FROM SACCHARINE FLUIDS
Year: 1885

page_text: I D* LOTHAR STERNBERG of the town of Brunswick in the Empire of Germany,
Chemist, do hereby declare the nature of my Invention for "AN IMPROVED PROCESS
FOR SEPARATING SUGAR FROM SACCHARINE FLUIDS” and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement :-
This said invention relates to an improved process for separating sugar from
saccharine fluids or from fluids or semi-fluids containing sugar crystals and is based
on the following hitherto unknown fact that if ammonia N H, be added in excess
or surplus to a solution of sugar saturated with quick lime or oxide of calcium
Ca O a precipitate is obtained consisting chiefly of a combination of sugar with
lime i.e. a lime saccharate.
The precipitation of the sugar is the more perfect according to the amount of
quick lime originally in solution that is to say the better the solution is saturated
with lime the more sugar will be precipitated or separated out of the fluid. This
precipitation or separation is facilitated by energetic stirring or shaking.
In order to render the precipitation or separation of the sugar from the non-
saccharine matter as perfect as possible an excess of the precipitant is necessary_80
that the entire fluid will contain about 10 to 15 per cent Ammonia N H.-The
precise chemical composition of the precipitate is of no importance to the present
process but it must be remarked that as a rule the same will contain 2 or 3
molecules of lime to 1 molecule sugar.
In order to carry this present invention into effect, proceed as follows:-
A saccharine solution (juice of plants, syrup, molasses etc) which if necessary is
so far diluted that it contains at the outside 12 per cent or what is best about
10 per cent sugar is, as is well known from the so called "Substitution process" or
other process for obtaining the sugar from molasses, saturated with quick lime or
oxide of calcium Ca O in such manner that powdered lime in finely divided form
is continuously stirred into the solution until the same is fully saturated (to
100 parts sugar 40 to 60 parts lime).
It is a matter of course that the saturation can be effected in other manner for
instance by employing diluted hydrate of lime or a concentrated solution with
subsequent dilution etc but the above-mentioned method by means of which the
largest quantity of lime can be most readily dissolved is decidedly to be preferred.
By careful manipulation 30 to 40 parts quick lime (Ca O) are dissolved per
100 parts sugar.
It will in most cases appear opportune to separate the surplus lime and the
impurities contained in the same (such as silicio acid, oxide of iron etc) by means of
anitable devices Hilter nregges etc from the solution but it is not necessary

page_text: The sugar solution which is saturated with lime is contained in appropriate
vessels with stirring device into which ammonia gas is introduced whilst the stirring
operation is continuously carried out.
The precipitation will soon commence will increase with the increase of ammonia
introduced into the solution and will be ended as soon as a sufficient quantity of
ammonia has been absorbed.
A fixed rule as to the quantity of ammonia to be employed cannot be given as
the same must be varied according to the nature of the saccharine fluid, the
concentration of the same, the amount of lime contained in the fluid etc and must
in each case be ascertained by a previous trial operation.
The completion of the precipitating operation can be ascertained by taking a
small sample of the fluid, filtering the same and adding a large percentage of
ammonia in solution to the same and if the fluid does not become turbid the supply
of ammonia must be continued. In general the process will be ended when the
fluid has absorbed 10 to 15 per cent Ammonia N. H,
The precipitate must be separated from the lye in appropriate manner for
instance by means of filter presses with closed canals and is then preferably washed
with a 10 per cent solution of ammonia.
The ammoniac gas is produced. at the beginning of the process by any known
method but during the working the ammoniac can be reused by recovering the
same from the waste lye which is for this purpose warmed so that only such
quantity of ammonia which is lost by becoming volatilized has to be replaced.
The mechanical devices must as a matter of course be so constructed and arranged
that as little ammonia as possible be lost.
Instead of feeding ammonia gas into the saccharine solution a concentrated
solution of ammonia can be added to the fluid so that the entire mass of fluid will
contain about 10 to 15 per cent ammonia, but the employment of ammonia in gas
form is decidedly preferable as a more concentrated spent lye and smaller and
simpler apparatus can be employed.
Similar precipitates to those produced by employing ammonia can be obtained by
using caustic potash or caustic soda in excess, but the technical application, of these
bases for precipitating or separating out sugar is not advantageous as they are on
the one hand too expensive and their recovery costs too much, and on the other
hand the purifying of the saccharate so obtained is attended with considerable
difficulties.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
The process for precipitating or separating out sugar from saccharine fluids (the
juice of plants, molasses, syrups, spent lyes from processes for obtaining sugar from
molasses etc) as lime saccharate in such manner that ammoniac in the form of gas
or aqueous solution (or caustic potash or caustic soda) is added to a saccharine fluid
previously thoroughly saturated with lime substantially as described.
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Witnesses,
EDWIN A. BRYDGES.
ANTHONY STEFFEN.
DR LOTHAR STERNBERG.