An Improved Process for Treating the By-products of Sugar Works and Sugar Refineries.
Year: 1896

page_text: Date of Application, 16th Jan., 1896-Accepted, 14th Nov., 1896
COMPLETE SPECIFICATION.
An Improved Process for Treating the By-products of Sugar Works
and Sugar Refineries.
I, MARCUS SACHS of 4 Ekaterinenstrasse, Kiew, Russia, Manufacturer,
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:-
In sugar works the boiling of the by-products to string test and the crystallization
thereof has hitherto been carried out, according to the methods employed,
either in jacketed reservoirs or in mixing vessels or pans with jackets in which the
products are cooled and heated and sugar is added to them because it was up till
now impossible to obtain a complete crystallization of the by-products in the
vacuum apparatus. In both cases there is obtained after the crystallization of the
second product resulting from the first crystallization a sugar containing residuum
(3rd product) which is subjected to a third crystallization whenever the normal
yield of sugar is to be extracted from the materials.
According to my invention, which is hereinafter more fully described an equal
or greater quantity of yellow-sugar is obtained from the 2nd product than from
both of the above mentioned crystallizations put together whilst the residuum of
this 2nd product consists of a-molasses which owing to its low percentage of sugar
and to its quotient of purity is in no respect inferior to the residuum of the
crystallized 3rd product of the old methods and is quite as unsuitable for further
crystallization.
(a.) Under my invention the residuum, 2nd product, of the first crystallization of
the mass is boiled in an ordinary vacuum pan along with repeated additions of the
same residuum until a sample thereof, placed on a piece of sheet glass, shows the
When the mass
sugar in the residuum to be in a thoroughly crystallized state.
shows a quantity of crystals of a medium size, about half of the contents of the"
apparatus (ie. down to the surface of the coil pipe) is drawn off into a mixing
vessel of simple construction and non-jacketed for heating and cooling the product
and without the addition of sugar for the purpose of promoting crystallization or of
increasing the size of the crystals.
The quantity drawn off in this manner is replaced by repeated supplies of the
product and the whole mass is kept boiling. The withdrawing and replenishing of
the product is, preferably, carried out continuously and the mass is kept constantly
boiling.
(b.) If, at the commencement of the treatment, i.e. when the vacuum pan is first
filled, the desired crystals are not formed in large quantities by the additions as afore-
said, then half of the contents of the pan in its condition after long boiling is run off
into the mixing vessel whilst new additions are supplied to the vacuum pan whereby
the desired crystallization is obtained, when the treatment proceeds. as set forth in
paragraph a.
(c.) This boiling for crystals, with additions, is continued for from 2 to 5 days as
long as there does not appear with the first crystallization a second one of a mealy
or floury character, as soon as this takes place the whole contents of the apparatus
are run off into a mixing vessel already partially filled with the mass.or into an
empty one, and the treatment is recommenced with boiling and running off the
disposable raw 2nd product as hereinbefore described under paragraphs a and b
hereaf

page_text: (d.) To produce, as quickly as possible, the desired crystallization it is advisable
to keep the additions to be supplied to the apparatus at a higher temperature than
that of the apparatus itself whilst effecting the boiling.
(e.) The mass is left in the mixing vessels for from 3 to 6 days after each vessel
is filled. The duration of the crystallization period depends upon the number of
mixing vessels in the works and upon the quantity of the 2nd product to be
subsequently treated and which should correspond to the capacity of the vessels.
In the place where the mixing vessels are located the temperature should be
about 25° R. although a higher temperature would not be injurious to the
crystallization. The crystallized product can be much more easily treated by the
centrifugal apparatus than masses produced by the usual processes.
Experiments gave the following results:
(f) The run-out mass carried in a heated state to the centrifugal apparatus did
not yield in any single case less than 22% of yellow sugar containing 94% of pure
The yellow sugar polarized therefrom gave 91-84 sugar 92-1 quotient of purity.
The residuum (3rd product) 45.65 sugar and 52.0 Q. of P.
At my sugar works in Prytzki (Kiew Government) where between the
17th September and the 16th November of the last "campaign" or season,
59395 lbs. of 2nd product were treated, a yield of 24468 lbs. of yellow sugar was
obtained, that is to say, 41.2%. The whole production of the works was treated,
by way of experiment, according to my process, but the boiled mass could not be
kept in the mixing vessels for a longer period than 3 days as the vessels available
for a longer crystallization were too small. As a consequence the above results,
although highly satisfactory, do not show to the full extent the advantages to be
derived from the process especially as the crystallization of the 3rd product was
not carried out. The whole residuum (boiled 2nd product) of 59395 lbs. yielded
67-35% of sugar 75-34 Q. of P. The yellow sugar obtained, 24468 lbs., yielded
92-45 sugar 94-01 Q. of P. The residuum obtained from the 2nd product (i.e.
the 3rd product) yielded 48-65% sugar 58.27 Q. of P.
The Prytzki sugar works were supplied throughout the course of the
"campaign" or season with only (1) 1st product (2) 2nd product and (3) feed
molasses. On the 17th December when the treatment of beetroot was terminated
the works were left without a single pound of by-product and with only a small
quantity of yellow sugar which remained from the last mixing vessels and was not
converted into white sugar. The works only produce white sugar.
During the
treatment aforesaid filtration by means of bone black was left off without any
noticeable injury to the quality of the sugar produced.
(9.) The total yield of raw sugar or white sugar is equally great from both the
first and second crystallizations with the improved process, no matter whether the
mass of the first crystallization has been more or less boiled or is of a better or
poorer quality, or whether more or less has been obtained in the centrifugal machine
at the first action.
Filtration by means of bone black can be dispensed with without fear.

page_text: The yield or gain and also if it is possible to carry out a further crystallization is
determined by the quantity of sugar in the residuums of the 2nd product.
With reference to this further crystallization I beg to refer to my tabular
statement herein before given where it is shown, that, from the 7th to 9th day,
there was neither an increase in the yield nor a diminution in the quotient of
purity (52 sugar and 52 Q. of P.). In this statement it will be seen that the
greatest gain from the crystallization occurred on the 6th day when the treatment
was practically finished everything being extracted from the first and second
products that could possibly be extracted in a crystalline form.
The control of the yield during the treatment is very simple; it is sufficient to
have a small automatic weighing machine for the 3rd product in order to quickly
indicate at any time, by a reliable valuation, the minimum stock of the
2nd product (i.e. the amount remaining in the mixing vessels) as well as the
probable loss.
The gain of the Prytzki Sugar Works, amounted during the last season to
12.91% of white crystalline sugar from the weight of the treated beetroot.
B. In sugar refineries the boiling of the last product in accordance with my
invention will save at least one crystallization while a greater total yield of sugar
will be obtained from the products.
The invention is equally suitable for treating the by-products of sugar cane
factories.
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
consider novel and desire to claim is :-
1. The boiling of by-products for crystals along with repeated additions in a
vacuum pan or other like evaporating apparatus and keeping the products to be
supplied to the apparatus at a higher temperature than that of the vacuum
apparatus, substantially as and for the advantages herein before set forth.
2. The process for treating sugar by-products substantially as hereinbefore
described.
Dated this 15th January 1896.
H. D. FITZPATRICK,
70 Wellington Street, Glasgow, Agents.