Improved Process for the Purification of Saccharine Juices and Apparatus therefor.
Year: 1897

page_text: Date of Application, 3rd Dec., 1897
Complete Specification Leit, 2nd Sept., 1898-Accepted, 3rd Dec.,
1898
PREDIONAL DILUITICATION.
Improved Process for the Purification of Saccharine Juices
and Apparatus therefor.
I, JEAN JULES HIGNETTE, of 162, Boulevard Voltaire, Paris, in the Republic of
France, Engineer, do hereby declare the nature of this invention to be as follows:---
My invention relates to the purification of saccharine juices obtained from sugar
cane, beet root, maize or the like, and has for its object in the treatment of juice
coming from the diffuser to enable the ulterior operations of double or treble car-
bonization to be dispensed with whilst obtaining a better operation and rendering
easier the ultimate work in the sugar factory.
The juice coming from the diffuser is mixed by means of stirring apparatus
or agitators with oxide of calcium (quicklime) in the proportion of 2 to 3 thousandths
according to the period of manufacture instead of 25-30 thousandths at present
employed in beetroot sugar factories, the said oxide of calcium being either in the
form of powder or milk of lime. This limed juice (or juice treated with baryta if
preferred) is decanted into a reservoir and the decanted portion allowed to flow
into a number of centrifugals varying according to the size of the factory.
Under the action of centrifugal force and of the lime in solution. in the juice, a
muddy layer of slight consistency is formed on the walls of the drum in each
centrifugal which layer contains a large proportion of the organic substances con-
tained in the diffusion juice of the beetroot. If to the action of lime that of a
current of carbonic acid gas be added simultaneously in the centrifugals, said gas
being derived from the lime kiln, there will be formed a carbonate of lime in a
nascent condition which will be precipitated on the walls of the baskets together
with about 30% of the organic substances contained in the juice. This partially
carbonated mud is blackish and charged with organic material, but relatively poor
in sugar because the sucrate formed is decomposed gradually by the carbonic acid.
Finally, if it be desired to simultaneously bleach the juice, gaseous sulphurous
acid is introduced into the centrifugals and in such case the latter must be pro-
vided with hermetic covers or lids. The juice is discharged emulsioned by the
gas. It is already very fluid and almost entirely bleached and its purification
is completed by a second slight liming whilst cold, in order to precipitate all the
lime in the condition of carbonate and to absorb the excess of carbonic acid.
Finally it is heated to about 80° in order to terminate the elimination of the
gas and to complete the precipitation. It is then filtered and sent to the boiling
down pan.
As the precipitate accumulated in my first experiments on the walls of the
baskets of the centrifugals, increasing in thickness, and when the juice discharged
appeared muddy or turgid, the centrifugals had to be stopped in order to remove
the precipitate. This was the difficulty in all processes having for object the
decantation of limed juice by the use of centrifugals with solid baskets.

page_text: These stoppages in addition to considerable loss of time necessitate an increase
in the number of centrifugals and give rise to a considerable expenditure of labour.
Further the loss of sugar in the mud is somewhat considerable.
In order to avoid these stoppages and the cleaning of the baskets I have im-
proved my previous process and rendered the work of purification continuous by
employing solid baskets divided into two parts of their height by a diaphragm as
in certain milk separators. In the present case the sugar or saccharine juice is
received under the diaphragm and above the diaphragm the liquid mud. This
mud is delivered into an agitator together with that arising from the deposit of
the decanted liquor in the tank for the limed juices. In this mixer or agitator it
is lixiviated and diluted with low saccharine liquor, a few thousandths of lime are
added thereto and the whole is discharged into a centrifugal having a solid basket
but without horizontal diaphragm and at the same time an excess of carbonic acid
is delivered therein.
Then under the action of centrifugal force there is formed carbonate of lime
which renders the scum dryer and enables it to be rejected as worthless because
it only then contains 30 % of moisture and 3-4 % of sugar.
Improved Process for the Purification of Saccharine Juices
and Apparatus therefor.
I, JEAN JULES HIGNETTE, of 162, Boulevard Voltaire, Paris, in the Republic of
France, Engineer, 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:-
All specialists are agreed upon the advantages which would result from a de-
fecation when cold and an immediate separation of the precipitate produced by
the action of lime in cane or beetroot sugar manufacture before the saturation is
effected by means of carbonic, sulphurous or other suitable acids. But the diffi-
culty of filtering defecated juices has hitherto rendered impossible this method of
procedure.
It is precisely this process of defecation whilst cold that I have economically
obtained by means of various improvements which I will now explain and which
enable me to dispense with the operations known as the double or triple car-
bonisation whilst obtaining a better purification of the diffiusion juice and enabling
the ulterior operations for the manufacture of sugar to be more easily carried out.
An apparatus for carrying out the operation is shown in sectional side view in
the accompanying drawings to which reference will be had.
This apparatus comprises two mixing agitators A and B; a decanting tank C;
centrifugals F F¹ having solid drums T T and with and without a diaphragm D
respectively, the former for removing separately and continuously the purified
juice and the liquid mud, and the latter for the treatment of the said mud; a
mixing agitator E receiving the mud arising from the decanting tank C before
said mud is admitted into centrifugals F1 without a diaphragm, and receiving the
mud from the centrifugals F; a mixing vat M serving as a saturation and heating
pan; and a gas container G provided with a blowing engine (which is not shown)
for discharging gas directly into the centrifugals.

page_text: The juice discharged from the diffusion apparatus or the sugar mills is mixed
whilst cold by means of agitators A and B with oxide of calcium (quicklime) in
the proportion of 2-3 thousandths of quicklime according to the period of manu-
facture (instead of 25-30 thousandths at present employed in beetroot sugar
manufacture) or with a quantity of 5 thousandths or more if it is a question of
cane, the oxide of calcium being either in the form of powder or in that of milk of
lime.
The lime acts on the sugar reducers of the cane more particularly by combining
with organic substances other than sugar. These limed juices (or juices treated
with baryta if preferred) are decanted in a reservoir C and the decanted portion
allowed to flow by pipes I and H into a variable number of purifying centrifugals F
according to the size of the factory.
Under the action of centrifugal force and of the lime in solution in the juice,
a muddy layer of slight consistency is deposited on the walls of the drum "T in
each centrifugal F, which layer contains a large proportion of the organic sub-
stances contained in the diffusion juice from beetroots, or in the cane juice,
amounting to about 30 % of the weight of the beetroot in the former case and
more in the case of sugar cane juice because the organic impurities prevail more
in cane juice. If to the action of the lime there be simultaneously added in the
centrifugals that of a current of carbonic acid gas, sulphurous acid or other suit-
able acid, by means of a pipe K leading from the gas container G, there will be
formed at the discharge spout a perfect emulsion of juice and gas which gives rise
to a very rapid reaction. At the same time the organic substances contained in
the juice combined with the lime are precipitated on the walls of the solid drum.
The mud in beetroot sugar making is black charged with organic substances but
relatively poor in sugar because the sucrate formed is decomposed gradually by
the carbonic acid. If it be desired to simultaneously saturate the lime and im-
mediately bleach the juice, gaseous sulphurous acid or hydro-sulphurous acid is
introduced in the centrifugals and in this case the latter must be provided with
hermetically closed lids or covers.
The juice in the centrifugals F which has been emulsioned by the gas or gases
arriving by the pipe K from the container G is then already very fluid and almost
entirely bleached and is discharged from the centrificals through a bent pipe L.
Its purification is completed by a second slight lining whilst cold in order to
precipitate all the lime in the state of carbonate if it be a question of beetroot
juice; or another saturation is formed if it be a case of sugar cane juice.
Finally the juice delivered by the pipe L which runs behind the centrifugal It
is forced by an ordinary pump Q through a pipe S into the mixing and heating
vat M where it is heated to about 80° centigrade in order to complete the elimina-
tion of the gas and finish the precipitations; the juice is then filtered and sent to
the boiling down plant.
The precipitate accumulates in the first stages on the walls of the drums of the
centrifugals F, increasing the deposit, and when the juice is discharged turbid, the
centrifugals are stopped in order to be cleaned of the precipitate. This is a neces-
sity with all processes having for their object the purification of limed juice by
the use of centrifugals having perforated or solid drums. These stoppages in
addition to a considerable loss. of time render it necessary in fact to increase the
number of centrifugals and give rise to and necessitate a large amount of handling
and further the loss of sugar in the mud is very considerable.
In order to avoid these stoppages and discharges of the drums, I have improved
my preliminary process and make the purifying operation continuous by employ-
ing solid drums T divided vertically into two parts by a diaphragm D as in certain
milk separators. In the present case the saccharine juice collects above the
diaphragm D and is discharged through the pipe L as aforesaid, whilst the liquid
mud which is heavier collects below the diaphragm and is forced through a bent
pipe N into an agitator E along with that arising from the deposit of the decanta-
tion of the lime tank C which enters the agitator E by a pipe R. In this agitator

page_text: it is agitated and diluted with the sugar-juice-wash, some thousandths of lime are
added thereto and the whole is discharged by means of an ordinary pump P through
pipes 0 0¹ into a trough Z and thence through pipes 0% into a centrifugal F¹ hav-
ing a solid drum T¹ but without a horizontal diaphragm and at the same time an
excess of carbonic acid is conveyed therein by means of a branch K¹ from the
pipe K aforesaid. There is then formed, under the action of centrifugal force,
carbonate of lime which renders the scum dryer and allows it to be rejected as
valueless because it only contains 30% of moisture and 3-4% of sugar.
The juice from this centrifugal F is discharged through a bent pipe L₁ into the
pipe L leading from the centrifugal F and is forced together with the juice in
the pipe L (which runs behind the centrifugal F) into the pump Q which raises
it through the pipe S to the mixing and heating vat M as before described.
The precipitate formed by centrifugal force in the centrifugal F does not
accumulate in the drum but is removed (as produced) through the pipe N as before
described so that there is no need to stop the centrifugal at certain intervals to
empty it. This continuous working thus effects a considerable saving in time and
labour.
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:-
1. The purification of saccharine juice and the drainings of centrifugals by the
use of very small quantities of lime (2-5 thousandths) said limed juice being then
. introduced with or without carbonic acid or the like into centrifugals having solid
drums revolving at high speed in which, under the action of centrifugal force, the
scum is deposited containing a large proportion of the organic substances, the said
scum being removed in a continuous manner from the saccharine juice, sub-
stantially as hereinbefore described.
2. In the purification of saccharine juice and the drainings of centrifugals, the
separation from the mud or scum hereinbefore mentioned, of the saccharine juice
contained therein, and the drying of the said mud in a centrifugal having a solid
drum under the action of centrifugal force, substantially as herein before set forth.
3. For the carrying out of the herein described process the application and use
in combination of mixing agitators A and B; a decanting tank C; centrifugals F F¹
having solid drums T and with and without a diaphragm D respectively, the former
for removing separately and continuously the purified juice and the liquid mud,
and the latter for the treatment of the said mud; a mixing agitator E receiving
the mud arising from the decanting tank C before said mud is admitted into
centrifugals without a diaphragm, and receiving the mud from the centrifugals F;
a mixing vat serving as a saturation and heating pan M; and a gas container G
provided with a blowing engine for discharging gas directly into the centrifugals;
the whole substantially as herein before described and shown in the accompanying
drawings.
E
1000
WM. P THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.