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Jan’ 7’
` F. N. RAWLINGSA En;
_2,413,784
ION-IG EXCHANGE OPERATIONS
Original Filed Jan. 14, 1942
4 sheets-sheet
_tlkmowviœhì
Rlu»AnBitT_ lbk
INVENTORS
y
FRANKLIN IY. Ra w1. mas
_
5Y
Lows of Gear-nov
ATTORNEY
.
7, 1947~
l
F. N.- RAwLlNGs nm.
Ionic
ExcHANGE
OPERATIONS
original Filed Jan. 14,194.2l
»@.QS3_um9Nkèäb6t.iQlkä//muhßw.
2,413,784 '
l
'
'
'
4 sneets'fsneet :s
Jan. 7, 1947.'
’ F. N. RAwLlNGs‘Ei-AL
IoNIc EXCHANGE o?ERATIoNs
f Original Filed‘Jan. 14, 1942
2,413,784
4 Sheets-Sheet 4_
FIG‘.v 4.
j C» T/oN ExcH/INGER SM1-10N
'
-
SnruRfvrlo/y PHASE) ^
ATTORNEY .
„Patented Jan.- 7, 1947
» :2,413,784
UHTED STATES- PÀTEN T OFFICE
2,413,784
'
> IONIC EXCHANGE OPERATIONS
_Franklin N. Rawlings, Westport, Conn., and
Louis deGeofroy, New York, N. Y., assignors to
The Don- Company, New York, N. Y., a corpora
tion of Delaware
Original application January 14, 1942, Serial No.
426,718. Divided and this application vDecem
ber 4, 1943, Serial N0. 512,894
_
l
This is a division of my
3 Claims.
patent application
»
(Ci. 127-55)
2
_ bed ready for operation in the next cycle, while
the Ca leaves the system in the spent auxiliary
parent application relates broadly to ionic ex- ' , regenerant
liquor.
change operation, and speciñcally to a manner of
There
now
regenerating a bed of cation exchanger material 6 application: follows an exact copy of the parent
which operates in the H-ion cycle and requires
This invention relates to improvements in the .
H2SO4 as a regenerant solution. The parent ap
conduct of ionic exchange operations. More spe
plication covers the procedure of treating the ex
ciiically, this relates to the use ofkcation exchang
hausted or saturated bed of exchanger material
ers
operating in the hydrogen ion cycle. That
with an auxiliary regenerant solution prior to ap
is to say, it relates to the treatment of solutions
plying the HzSOi regeneration. 'I'his auxiliary
from which cations are to be removed by means
step is for the purpose of displacing from the
of a cation exchanger in exchange for H-ion,
saturated bed those cations (for instance Ca)
which exchangers must be regenerated after their
that are precipitable insofar as they would form
exchange
capacity has been exhausted and they
with the H2804 regenerant solution insoluble re
-action products. In this Way, the precipitable 16 have become- saturated with cations from the
solution being treated.
«
.
ions are replaced with the molar equivalent of
An
ionic
exchanger
is
usually
represented
in
the
cations that are non-precipitable (such as Na and
form
of
a,
unit
or
cell
containing
a
bed
of
the
K) insofar as they will form with the HzSO-l
regenerant solution soluble reaction products. 20 exchanger material proper which is usually gran
ular. An exchanger has the ability to absorb from
’I‘his procedure including‘the auxiliary treatment
the solution an ion of an ionized solute and to
step makes it possible to avoid undesirable pre
give off into the solution in exchange anion of
cipitations in the exchanger bed coincident with
another kind even though of like electric charge.
the msm regenerations.
Therefore, cation exchangers as a class exchange
Reference is also had to a copending patent
charged ions, whereas anion exchangers
application Ser. No. 376,717, ñled January. 31, 25 positively
as a class exchange negatively charged ions.
` 1941, by Franklin N. Rawlings, who is one of the
vAs the solution is passed through and contacted
co-inventors in the present application. The co
with the ion exchanger bed, the direct exchange
pending application describes an ionic puriñcation
process for sugar bearing liquids or sugar juices, 30 of respective ions between the solution and the
exchanger continues until the exchanger is .satu
»in which the juice is subjected ñrst to a cation ex-‘`
rated
with the ions being removed from the solu
change, and then to an anion treatment step.
tion and its exchange capacity thus exhausted.
In describing a complete operating cycle this co
The exchange capacity cari then be restored by
pending patentapplication recommends for thev
regeneration of a 'synthetic resinous exchanger 35 treatment of the exchanger with a suitable regen
erant solution. The saturation on the one hand,
bed an H2SO4 solution of a concentration on the
and the regeneration on the other hand, represent
order of 5%.
»
'
the main phases of the operating cycle of an ex
The present divisional application covers the
changer, whereby the exchanger may be used over
procedure of treating a solution containing both
' the precipitable and the non-precipitable `kind of 40 and over again. The chemical reactions involved
in the operating cycle are reversible'equilibrium
cation, first in one bed to which the precipitable
reactions.
-
Serial No. 426,718, filed January .14, 1942. The
kind becomes ñxed in exchange for non-precipi
table cations. As a result of this auxiliary treat
ment step, eiliuentsolution leaving the ñrst bed
More particularly the invention has to do with
such beds that make use of granular exchanger
` material that is of organic
nature and acid re
contains only non-precipitable cations. It is then 45
sistant to the extent that it Will remain bodily
treated in a second bed where H-ion exchange
stable in the presence of certain strong acids (for
may take place without the danger of sulphate
instance,ìHCl and H2SO4) by means of which they
precipitation in the bed. In this way. the pre- `
are to be regenerated. 'I'his belongs to a class
'
cipitable cations are removed from the' solution
in a separate step or bed which isolates the unde 50 ' of exchangers now newly called organolites in
distinction from the inorganic base exchangers `
sirable cations, and which auxiliary bed is regen
known
as zeolites. Organolites are being used
erable with an inexpensive regenerant solution
currently in sugar making, that is to say, in the
such as NaCl. By the auxiliary regeneration with
puriñcation phase of the sugar juice treatment, a
NaCl the isolated cations such as Ca are replaced
with non-precipitable Na rendering'the auxiliary
use that will be described herein as an example
by which to convey an understanding of the ionic
2,418,794
environnient of this invention. The essence cf
the method of purifying the juice or sugar bearing
.
4
and “B” indiscriminately in exchange for its own
cations until it is substantially saturated with
solution through ionic exchange treatment is that
the juice is sent through a sequence of cation and
anion exchangers, with the net result that dis
solved salts in the juice are removed in exchange
for the molar equivalent of pure and evaporable ,
Áwater. The mechanism of this ionic substitution
in the treatment of sugar juice -will be described
10
more completely further below.
A cation exchanger of the organolite type, be
ing of organic nature and acid resistant, can be
regenerated with one of the commonly known.
strong acids of which HC1 and H2504 are well
known examples. While the sulphuric acid, be 15
ing a cheaper one, may be considered preferable
absorbed cations, that is until its exchange ca
pacity is exhausted. This period is herein called
the, primary period of' ionic exchange of the ex
changer.
If the sa-me fresh solution is continued
to be passed through the `saturated exchanger, the
latter will begin to manifest its selective char
acteristics by releasing the previously absorbed
cation of the salt “B” in exchange for preferred
cations of the salt “A" in the solution. This will
continue until the exchanger is saturated with
only the preferred cations of the salt “A.”
for reasons of economy, we have found its use to
be impractical in the exchange treatment of solu
- Cation exchangers such as herein contemplated
have a. preferential action for I'the alkaline earths
such as Ca and Mg over the alkaline metals such
as represented :by K and Na, all of which cations
are found to ~be present in varying degrees in
sugar juice.
'
tions from which the cation exchanger has re-`
That is to' say, it has been found that ionic
moved and collected cations among which are 20 exchange
materials operating in the hydrogen ion I
some that form with the regenerant sulphuric
cycle have a preferential actiony or avidity for
acid a poorly soluble or insoluble sulphate. Such
calcium on the one hand over potassium and so
a precipitate or deposit or coating upon the gran
dium on _the other hand. Thus, if an exchange
ules of the exchanger material presents an ob
stacle to the proper exchange function of the ex 25 bed is started operating on a solution containing
all these cations, it will iirst remove all of them
changer, and greatly reduces its eiîectiveness. In
from the solution flowing through the exchanger
the specificv case-of ionic exchange purification
treatment of some sugar bearing juices or syrups,
bed. But when the bed reaches saturation, that
insoluble calcium sulphate precipitate to deposit
upon the exchanger material during regeneration
with HzSO4.
The object of this invention is to overcome this
sium for calcium in the incoming juice, and con
tinue in this preferential exchange until substan
is the exhaustion of its hydrogen exchange ca
calcium may be present in them to an objection
able degree _and under ordinary conditions of ex 30 pacity, it will discontinue removing sodium and
potassium from the solution and begin to ex
change treatment, may collect in the exchanger
change the already absorbed sodium and potas
to an extent that will cause undue quantities of
tially all of the sodium and potassium it has pre
viously absorbed is replaced by calcium, whereby
finally the exchanger bed is left~Ca-saturated.
diñiculty and to propose a process which makes
possible the .use ,of sulphuric acid as an inex
In this secondary or preferential exchange reac
tion, the exchanger is, so to speak, operating in
pensive regenerant, without the occurrence of the
the
sodium and potassium _cycle instead of in the
objectionable precìpitaes from the H2804 reac 40
former hydrogen ion cycle. '
tion with such ’trouble causingcations as calcium
or others.
’
Ali‘or the same reason, if an exchanger is as
sumed to have been saturated with a series of
`
The invention proposes to isolate the undesir
able or precipitate forming cations by means of se
lective or preferential ionic exchange, prior to ap
cations of different amnities, it is possible to dis
45 place from the exchanger some of these ions,
which have a weaker afñnity to the exchanger
than the displacing ion. In this way all ions
tion exchanger. It is proposed to utilize certain
can be displaced excepting the ion or ions having
selective or preferential exchange characteristics
equal or greater affinity to the exchanger than
of the exchanger material. Such characteristics
displacing ion.
i
_
.
are in the nature of a certain order of exchange 50 theForexampl
, if a cation exchanger were satu
lying HzSOi as a regenerant to an exhausted ca
affinity possessed by the exchanger with respect to
a variety of ionic substances present in the solu
tion. that is being treated by the exchanger. In
other words, the cations in the solution form a
sequence or series as regards their exchange af 55
iinity with respect to the exchanger. I But it
should also be understood that this nautral se:quence is modifiable in effect by a deliberate
change of the concentrations of the respective
ions in the solution. That is to say, the natural
preference of the exchanger for‘one cation can
be overcome or suppressed by another cation even
rated with Ca and K-ions, one could treat the
exchanger with a Cach-solution and thereby dis
place thev K-ion with Ca-ion because of the 'nat
ural preference of the exchanger for Ca. The so
lutiorr‘is thereby changed to potassium chloride.
Assuming all the K-ions to have been thus dis
placed, ‘the exchanger would be- left saturated
with Casàons exclusively because of its preference
for Ca o' er K. However, this natural preference
of the exchanger for Cafmay be overcome or sup
pressed by a suitable choice of concentration of
a cation of lower afñnity in solution, such as KCl,
That is to say, with the K in 'sufficient concen
though of weaker añlnity with respect to the ex
changer, provided it is allowed to act upon the
exchanger in a sufficiently strong concentration. 65 tration, when the Ca saturated exchanger is con- v
tacted with the KCl solution, all the Ca-ion in
The aiiinity characteristics of an exchange mayI
turn may be replaced with K-ion, whereby then
be explained by way of general example as fol
the exchanger will be left all K-saturated.
In order to attain the object of this invention,
Assuming a solution contains a mixture of two
the cation exchanger is allowed to become satu
salts “A” and “3" as solutes, and that the ex
lows:
.
Y
changer l‘las a preference or aillnity for the cation
of the salt "A” over the cation of the sait “B,” if .
rated with a variety of cations from a solution,
including those >ions that are potentially capable
of forming undesirable precipitates on the ex
the solution is passed through the exchanger bed
vchangermaterial, when in reaction with HzSOi
that has been freshly regenerated, that bed wil1
during the subsequent regeneration of the ex
absorb all the cations from both the salts “A” 75
.
2,413,784
changer with that acid. However._according to
the invention, before applying this regenerant
left in the exchanger. Thus„the acid or positive
ions oi’ the juice are re»A oved from it while pass~
ing through a cation exchanger bed and the nega
tive or acid forming ions are removed from it
acid, the exchanger is ñrst subjected to an ionic
displacement operation by way of treating it with
an auxiliary solution, whereby the precipitate
forming ions are replaced with the molar equiv
alent of ions that will not form H2504 reaction `
while passing through> a subsequent anion ex- y
changer bed.
This cation and anion exchange mechanism products as precipitates. For example, a calci
will be more precisely understood from the fol-`
um containing cation exchanger may be treated
lowing example:
,
.
A
_
v
with NaCl solution of suiiicient strength until all 10
Sugar ,'luicev containing KCl goes in the cation
the Ca in the exchanger yhas been replaced with
bed, in, passing through which KCl and.l HX
Na, whereupon it may be regenerated with H2SO4
in the hydrogen ion cycle, whereby soluble so- ,
(X being the structure ofthe cation exchanger)
of the bed become IQ! and HC1. 'rhe HC1 that_
dium sulphate is produced. The spent regener
ñows from the cation bed with the juice is then
ant liquor thus passes from the exchanger with
out leaving behind any harmful sulphate deposits. 15 passed through the anion bed and, in so doing, the ,
incoming HC1 and the OHY (-Y being the struc
Inasmuch as the ionic puriñcation treatment of
ture of theanion exchanger of the anion bedr
sugar juices is herein chosen as an example em
become ClY and water, so that sugar juice flows
bodying this invention, and so that the environ
from the anion bed minus its intial V content of l
ment of the invention thus embodied may be
clearly understood, there now follows a brief de 20
During the regeneration in the cation bed, if
scription of the chemical exchange mechanism
HC1 is-used as a, regenerant, that acid reacts'
whereby ionic impurities or dissolved salts in the
with the residual KX to form HX and KCl, the
sugar juice are subtracted therefrom and re
latter iiowing from the cation bed leaving the bed
placed with the molar equivalent of pure and
25 regenerated. If H2804 be usedas regenerant acid,
evaporable water. ’
KCl.
In extracting non-sugars and especially salts
from sugar-making juice or syrup, two main types
of exchanger beds are used. One is called the
cation exchanger bed that is characterized by its
`
‘
~
the spent regenerant liquor would accordingly
contain the K as K2SO4 which is a soluble sul
phate. During regeneration of the anion bed,
the incoming regenerant NaOH reacts with the
.use of exchanger material that operates on the l30 ClY to `form OHY _ and NaCl, which >latter flows
hydrogen-ion cycle and is adapted to collect from
the juice plus or positively charged ions repre
sented generally by calcium,vmagnesium, sodium
and potassium. That is, as juice is supplied to
the cation exchanger bed (or cell that contains
the bed) so as to ñow through it and out there
from, cations of the juice exchange themselves
for the hydrogen ions of the exchanger until
from the bed, leaving the anion bed regenerated.
Again, the problem lies with regeneration of '
the cation exchanger in view of the possibility
of sulphate deposits on the exchanger material.
Sulphuric acid being fromv one-third to one
fourth the price of hydrochloric acid, it is
preferable naturally, _to use sulphuric acid.
Cane juice, for instance, contains suiiicient cal
cium so that when sulphuricV acid is`used for
the exchanger bed becomes exhausted of its exe
change capacity and so saturated with vthose ca 40 regeneration, calcium sulphate is found or yielded
, in such concentration as to precipitatein‘the
tions that it ceases substantially’ to exercise fur
ther hydrogen> exchange activity.
Thereupon
the cation bed must be regenerated by contact
with a regenerant in the form of an ionized strong
acid such as hydrochloric or:‘sulphuric acids.
exchanger .bed during regeneration.
'I‘his pre
cipitation tends to block mechanically the normal
exchange function'of the exchanger bed, caus
ing a marked reduction in the exchange capacity
of the regenerated cation exchanger.
During regeneration, the reverse process takes
This invention proposes, therefore, a method
place in the exchanger, namely, » the residual
cations exchange with hydrogen ions of the acid
regenerant so that the cations »iiow from the bed
until the bed is recharged with hydrogen ions. 50
used in the regeneration of those exchangers.
Juice that passes from the cation bed has had
The remedy according to this invention lies in
its impurity content- of basic ions substantially
subjecting the exchanger to an intermediate
removed, but it yet contains chlorides, sulphates
treatment or conditioning step whereby the Ca
and other such negative ionic impurities. So the
juice, substantially rid of its positive ionic or 55 or precipitate forming cations are displaced from
the exhausted exchanger by actions whose po
cation impurities that have been left in the ex
changer, is passed to and through an anion ex
changer bed or cell that operates‘on a hydroxyl, '
cycle. In passing through the anion bed, the
chloride and sulphate, etc., ions of the juice are
exchanged for the hydroxyl ions of the bed until
theanion bed becomes saturated with chlorides
and sulphates, etc. Thereupon the saturated
anion bed must be regenerated by contact with
tential sulphates will remain dissolved in `the
spent regenerant liquor. This comprisestreat
e ingl an exhausted action exchanger bed with a
suiiiciently strong solution of common salt (or its
equivalent) to replacev the Ca of the vexchanger
bed with Na from the salt. This auxiliary treat
ment step leaves the exhausted exchanger sat
' urated mainly with Na 'and K, such being `the
- some ionized alkali hydroxide or carbonate, espe-' 65 representatives of the alkali metals and the al
cially sodium hydroxide. or carbonate. During
regeneration, the reverse process takes place,
namely, the residual chloride and sulphate,- etc.,
ions in the bed exchange with hydroxyl ions of
kaline earths respectively in the sugar juice. The
exhausted cation exchanger bed thus conditioned
or pre-regenerated in the Na cycle, can be safely
regenerated in the H-ion cycle, that is, with sul
the basic regenerant so that the negative ions or 70 phuric acid. Due to the absence of Ca in the
exchanger, no insoluble calcium sulphate will "
anions `iiow from the bed untilthe anion bed is
form. The sulphates of Na and K that will form,
recharged with hydoxyl ions. In passing through
are soluble and thus harmless to the proper func
the anion bed, the juice is substantially rid of its
tioning of the operating cycle of the exchanger
negative or salt-forming ions since they have been 75 bed.
v
2,418,784
7
changer body. Hence, there exists, yapproxi
According to one embodiment, or mode of op
eration of this invention, the total exchange op
mately speaking, a dividing line or relatively nar
row zone of transition between the upper ex
erating cycle is performed in two exchanger
stages. That is to say, the Juice is pamed through
a ñrst cation exchanger stage operating in the
auxiliary or Na regeneration cycle where all the
Ca from the juice is selectively collected by, and
then displaced from exchanger, whereupon the
thus conditioned juice is passed through a sec
i
hausted or saturated portion of the exchanger
body -and the lower non-exhausted or non-satu
rated portion of that body. This dividing line or
zone keeps shifting downwardly through the ex
changer body as the vcontinuously through-flow
ing solution leaves an increasing exhausted ex
changer portion behind as it advances through
a correspondingly decreasingv portion of non-ex
exchange stage operating in the H-ion re
generation cycle, where cations are removed that
do not form insoluble Rasoi-reaction products.
In this connection it is to be remembered from
`the foregoing, that all the Ca from the juice can
be selectively collected in the first exchanger
stage because the cation exchangers have a much
greater affinity for the calcium ions than for the
sodium or potassium ions. -That is to say, if the
exchanger becomes first exhausted with a variety
- of any such cations collected in it, then if addi
hausted or still active exchanger.
However, as
the dividing line is not necessarily a `sharp one, l
there will be- noticed a slowing down of the ex
change intensity as the “break-through” point
of the exchanger is being approached. _ This is
a warning that the fresh or regenerated ex
changer should be substituted for the one nearing
saturation. The regeneration of a bed proceeds
20 in asimilar manner through' the bed.
tional juice is contacted> with it, the exchanger
will, by reason of its preference, remove the Ca
_from the additionally flowingjuica-yielding in
Y ‘
One of a variety of organic- cation exchangers
considered suitable for the present purpose is of
the resinous type such _as exempliñed in the
United States patent to Holmes No. 2,191,853,
’exchange an equivalent quantity of sodium or
where the exchanger is described as a synthetic
'potassium which, it had previously removed and 25 resin of the polyhydric phenol formaldehyde type
collected.
'
which is sulphited to adegree such that its sul
If a suñlcient proportion of the cation ex- .
pur content is not less than 2.4%. An organic
changer (representing the ñrstexchanger stage)
anion exchanger considered suitable for the «pres
is left in the circuit after the exchanger has
ent purpose is also of the resinous type and is f
become exhausted with respect to hydrogen ion
exemplified in the United States patent to Adams
exchange, and if this is followed by other cation
„exchanger not exhausted with respect to hydro
gen ion exchange (this is the second exchanger
stage) the exhausted exchanger stage will selec
tively take up ‘all of the Ca while the non-ex
hausted exchanger stage will take up the K> and
Na. The first exchanger stage having become
all Ca saturated, can be treated with a solution
of sodium chloride (NaCl) of sufdcient concen
tration in order to substantially remove the Ca
from the exchanger by displacing it with Na.
and Holmes No. 2,151,883, describing the ex
changer as an insoluble .resin-like product ~ob
tained by the reaction of formaldehyde with an
aromatic amine. Exchangers of the type contem
plated for use inv connection with the present
invention, are substantially stable in the presence
of acids and alkalis.
- Other suitable organolite exchangers are: The
cation exchanger produced by the Resinous Prod
ucts Corp. of Philadelphia under the name or
After washing out -the residual NaCl from the
identification of Amberlite IR.1, and the anion
bed, the exchanger can again be used to take
These are‘exchanger materials of synthetic res
inous nature, and more specifically materials
which are prepared by the condensation of a dis
solved organic chemical of a group comprising
sulfonated phenols and aromatic amines, with
up more Ca from the juice, and the Ca-free juice
_then vbe passed through second stage exchanger
material active in the H-ion cycle in order to
remove the K and Na. The exhausted second
. stage exchanger bed containing the K and Na is
exchanger Amberlite IRA from the same source.
regenerated with HzSOs because it doesn’t con
an aldehyde.
',
, remove the Ca alone from the juice.
for convenience, but they are intended to beas
generic in their application to similar parts as
The invention possesses other objects and fea- Y
tain precipitate forming impurities, and after 50 tures
of advantage, some of which, with the fore
washing out the residual acid from the bed, this
going, will be set forth in the following descrip
second` stage exchanger- can' again be used to
tion. In the following description and in the
effect Na-and K-removal, in sequence to the_ claims, parts will be identified by specific names
first stage exchangerA bed or beds employed to
In the course of a complete operating cycle,
each of these exchangers, if exhausted, is to have
the art will permit. In the accompanying draw
ings there have been illustrated the best embodi
the residual juice therein displaced from the
ments vof the invention known to nie, but such
exchanger bed with wash water, and if deposits
have collected on the exchanger granules they 60 embodiments are to be reg'arded as typical only
of other possible embodiments, and the inven
' are toy be washed out,- before the exchanger if
subjected to contact with the regenerant solu
tion is not to be limited thereto.
The novel features considered characteristic
tion, Again, if regeneration is completed, the
residual regenerant is to be displaced and washed
of my invention are set forth with purticularity
out from the exchanger with water, before the 65 in the appended claims. The invention itself,
exchanger is again contacted with the juice, In
however, both as to its organization and its meth
this way undesirable reactions between ionic con
od of operation,'together with additional objects
stituents of the juice and regenerant solution
and advantages thereof, will best be understood
in the exchanger bed can be avoided and the
exchanger be kept in regular cyclic operation
with substantially undiminished efliciency.
The exhaustion or saturation of a fresh ex
changer bed with the solution flowing down
wardly» therethrough proceeds in continuous
fashion from the top to the bottom of the ex--
from the following description of a speciñc em
bodiment when read in connection with the ac
companying drawings in which:
Fig. 1 is a diagrammatic illustration of the
cyclic operation of the cation exchanger operat
ing as a single exchanger stage, in which the
2,418,784'
intermediate or auxiliary regeneration step
in the K cycle.
-
eration proper with H2SO4~of suitable concentra
tion, that is, regeneration in the H-ion cycle,
rig. 2 is similar to Fig; 1, except that the
intermediate regeneration is in the Na-cycle,`
as represented in the following equation: ‘
Lleaving Na and K to be removed from :the ex-`
changer by H-ion cycle'regeneration.A
__
(3)
lFig. 3 illustrates the two-stage method in which
the intermediate >or auxiliary regeneration is per
formed in the Na cycle in the iirst exchanger
stage, and- the H-ion regeneration (using I-IaSO4)
is performed in the second exchanger stage.
K
.
H
K-x-x + maso __. H-x-H + zmso
___.
__
’ That is to say, Hzsoi is started flowing through
_ 10
the K-saturated'exchanger bed, andv the condi
tion of the bed at the beginning of this phase is
designated as C5. This continues until all K-ion
are replaced with H-ion, the K being- yielded'by
ing an intermediate conditionjinthe operating
the exchanger and' therefore present in the spent
phases of the two cation exchanger beds, namely,
when the two-beds are partly exhausted during 15 regenerant liquor as K280i, that is, potassium
the saturation phase (see Fig. 4), and partly'- v sulphate that is soluble. Thereupon the exregenerated in the regeneration phase (see Fig. , changer can be re-used in the initial condition
C1 of the saturation phase, that is, at the begin
Figs. 4 and 5 illustrate the mode of operation
or operating cycle shown in Fig. 3, by represent- "
5)
_
,
,
.
.
' ning of the total operating cycle. Because ofthe
' absence of calcium sulphate deposits on the ex-`
the juice containing as chlorides Ca as well as 20
changer granules, this cycle can be maintained
K (as representatives of the _alkali metals and
In practicing the _invention according to Fig. 1,
of the alkaline earths respectively) is started
ñowing through a cation exchanger bed which is
freshly regenerated in the H-ion cycle, a condi
tion herein designated as Ci.
repetitively in smooth operation. .
_
However, sodium chloride (NaCl) is a suitable
and inexpensive auxiliary regenerant substance,
25 and its use as such is embodied in the two ymeth
The saturation of ‘
this bed by the through-ñcwing juice with Ca> „ .- ods of operation'accoi‘ding to Fig. 2 Vand Fig. 3
respectively.
and K proceeds according to the following equa- ‘
tion:
(1) H
l
Sugar juices and `
.
_
_
-
_
_
In Fig. _2, the saturation phase of the total
operating cycle comprises starting the iiow of
juice containing Ca `and K as chlorides, through
a suitable cation _exchanger which has been
freshly regenerated in the H-ion- cycle and there
`
Sugariuices and
X=Ca + syrups contain
H-J_i--H + Syrups
' containing __»
CaCliand2KCl
. _ ~.|
.
ingiHCl
fore has positive or H-ions available for exchange.' '
' This condition of the exchanger is designated as
the exchanger will become exhausted, as Ca and 35 C7. As the ñ'ow of juice is continued the exchange ,
reaction- between the available H-ion in the ex
K from the juice accumulate therein in exchange
changer withjthe Ca and K-ion in the juice pro
for the, available H-ion, this exchange reaction _
ceeds according to the Equation 1 as above. If
resulting in the formation of 4HCl (hydrochloric
acid) in the juice. ’I'he exhausted or saturated >lthis is continued until the available H-icns in
condition of the exchanger at the end of the .satu 40 the exchanger have been replaced with Ca -and
K-ion, the exchanger will have assumed the con
ration phase is designated as C2. AThe juice that
In due course the H-ion exchange capacity of
is having its Ca and K removed by the exchanger,
having thus becomes acidified in the process, is
ldition Cs in Whichit is all Ca-
and K-saturated.4
" The juice leaving the exchanger is thus rendered
free of Ca and K, although it becomes corre
then passed on to and through an anion exchange
treatment station Where the negative ion of the 45 spondingly acidiiìed since it contains the com
bined Ca and K equivalent in hydrochloric acid.
acid is replaced with OH-ion which combines
with the positive or H-ion of the acid to form
The thus acidiiied juice is passed to an anion y
treatment station (not shownin the drawings)
pure water (HOI-I or H2O). The dissolved salts
where the acid is converted into the molar equiv
or impurities (CaClz and 2KC1) originally present '
in the juice, are thus replaced by the molar 50 alent of H2O, as was described in connection with
the removal of cations _from the juice during the
equivalent of pure water. Since this invention
saturation phase in Fig. 1.
_ l
`
is concerned lwith improvements relating to the
_ The exchanger is vthen subjected to interme
cation exchange treatment phase, the anion ex
change station is not particularly shown in the
drawings.
~
'
'
_ The exchanger having become satuî'äte’d‘iwlth
Ca and K is then subjected to intermediate treat
ment or conditioning by auxiliary regeneration `in
the K-cycle. This proceeds according to the
following equation:
diate vor auxiliary regeneration, namely,- regen
55- eration in the Na-cycle, with NaCl solution as
-
'
‘
the auxiliary regenerant. The condition of the
exchanger bed at the beginning of this interme
diate phase is designated as C9, andit proceeds
according to equation'60 v(s)
_
«
Na
This is- continued until- all lthe Ca-ion in the
This means that the exchanger is treated with
65 exchanger will have been replaced with sodium
KCl solution of suiîìcient strength to displace and
replace the Ca, the initial condition of the ex
ion. The condition of the bed atthe end_of this
regeneration phase is designated as Cip.
Then begins the 'regeneration proper of the ex
changer during this treatment phase being desig
nated as Cs. This-is continued until all the Ca _in
the exchangerhas been replaced with-K, placing »
the exchanger in the condition designated as C4.
Thus the exchanger is .all K-saturated, as the Ca
is contained in the spent liquor as CaClz.
The exchanger can _now be subjected to regen-l
changer in the H-ion cycle by means of HzSOi,
which proceeds according to equation
à
'
2,413,794..
The condition of the exchanger at the begin
' ning of this iinal regeneration
12
exchanging H-i'on from the exchanger against
the Na and K-ion from the juice.
At the beginning of this saturation phase the
condition of the exchanger is designated as Cn.
phase is designated
as Cn. The exchange according to Equation 5
is continued until all Na and K-ion in the ex
changer have been replaced with H-ion from the
acid, when the exchanger bed will have reached
its fully regenerated condition designated as C12.
The saturation proceeds according to the equa
tion-_.
8
-
'
No
-
-
>
êizgar solution
l
Sugar solution
Consequently, the displaced Na and K are present
NaCl & 2K0] + H-X-H __» K-X-K -i-y containing
in the spent regenerant liquor as N2SO4 and
(from 6)
Iii
Na
21101
K2SO4. The exchanger bed is then ready to be 10
re-used at the beginning of the operating cycle
The Na and K saturation oi the exchanger ac
Where its condition was designated as C1.
cording to Equation 8 proceeds by continuing to
In Fig. 3 the invention is embodied in a two
iiow juice through the exchanger until substan
stage operating system, permitting the auxiliary
tially all available H-ion therein have been ex.
(Na-cycle) regeneration to be performed in the
changed against the Na and K-ion from the juice.
first exchanger stage, while the H-ion regener
when the exchanger will have become Na and
ation (using H2804) is performed in the second
K-saturated, a. condition herein designated as
exchanger` stage. That is to say, the juice is
Cia. 'I'he juice treated vduring this saturation
passed sequentially through both stages, while
phase emerges freeof Na and K, although con
each stage is regenerated in its own respective
taining the combined Na and K equivalent in hy
. cycle. In the first stage the juice is conditioned,
drochloric acid. The thus acidiñed juice is then
. by virtue of selective Ca-removal, for H-ion ex
passed on for treatment in an anion exchange
change treatment in the second stage period.
station (not shown in the drawings) where the
Because of the conditioning action of the iirst
stage, the cations present in the juice entering 25 acid in the juice is converted to pure water, as
above explained in connection with the operation
into the H-ion exchange phase, are of such a
according to Fig. 2 and Fig., 3.- .
kind that their H2504 reaction products will not
The second stage exchanger bed can now be
form objectionable precipitates during H-ion re
regenerated
in the H-ion cycle by means of treat
generation of the second stage exchanger. bed.
ing it with H2S04 of suitable concentration. The
For this purpose, the first stage exchanger bed
condition of the bed, when the regenerant acid
may be assumed to have been regenerated in the
starts entering it, is designated as Cin. - The ex
Na-cycle, so that it is saturated with Na-ion when
change whereby the Na and K in the exchanger
juice containing Ca and K as chlorides is started
are replaced with H-ion from the acid, proceeds
flowing through it at the beginning of the oper
ating cycle. The condition of the bed, when the 35 „ according to equation
juice begins to flow into it, is designated as C13.
(o) ` Ne
`
1‘1
- Since the exchanger has a preference for Ca
over Na, it will absorb the Ca` from the juice, re
x-X-K '+ 2H=so4 ___» H-x-H + Naso. + xiao.
No
`
leasing Na instead into the juice, rendering the
juice thus treated free oi.' Ca but leaving in it Na 40
This is continued until all the N_a and K will
and K according to the following exchange‘re
have been replaced with H-ion; when the ex
action equation
changer will have reached its regenerated condi
(6)
Na
tion herein designated as C». _ Spent regenerant
Sugar Solution + Na-- -Na -v Susar S olutlon -l- X=Cn 45
KCl 6c 208C):
Na
KCl & 4NaC l
a
,
liquor flows from the exchanger, containing the
displaced Na and K as NaaSO4 and K130i, both
-of which are ~soluble, and therefore harmless,
since they leave no objectionable and obstructive
This exchange is continued until all Na-ion in
deposits upon the exchanger material, whereby
the exchanger have been replaced with Ca-ion
from the juice, that is, until the exchanger is all 50 its exchange effectiveness might be interfered
with. The thus regenerated exchanger can then
Ca-saturated, a condition herein designated as
be re-used at the beginning of the H-ion regen--l
C14. The Ca-free juice is then passed on to the
eration cycle, where the condition of the bed is
second cation exchanger stage, while the first
stage exchanger bed is being subjected to Na
identified as Cio.
Another way of illustrating the method of iso
.cycle regeneration which proceeds according to
iating Ca from the juice according to Equations
equation
6, 7, 8, 9 is shown in the diagrams of Figs. 4 and 5.
(7)
Na
Instead of showing the initial and nnal condi
tion of the exchanger beds (as shown in Fig. 3),
Figs. 4 and 5 show an intermediate condition of
Ca
l
Na
the beds in their saturation and regeneration
phase respectively.
That is to say, NaCl solution of suiiicient strength
Fig. 4 shows the saturation of the two cation
is started to be passed through the bed then in a
condition designated'as C15. The NaCl solution
is of a strength suiiicient to suppress the initial
Ca preference vof the exchanger and to eiIect dis
placement of the Ca-ion therefrom. Consequent
ly,- when all the Ca has been replaced with Na.,
exchanger stages. The juicewhich is assumed
to contain appreciable amounts of Ca and K in
'the form of chlorides and as representing the al
kali metals and the alkaline earths respectively,
is shown to have passed through the first cation
exchanger stage long enough to have placed it
the exchanger is all Ca-saturated and in a con
into the condition designated as Cn. This bed
dition herein designated as Cie. The displaced 70 -was
originally regenerated in the Na cycle where
Ca is present as CaClz in the spent liquor flowing
by it has adsorbed N_a-ion, but in the condition -'
from the bed.
Cn the upper portion a thereof has become satu-_
Meanwhile the juice having been freed of Ca,
rated withv Ca in exchange for Na-ion because
'but containing 'Nal and K. is passed through the
of the preference or affinity of the exchanger for
75
second cation exchanger. bed for the purpose of
i3
2,413,784
i4
Ca. while the lower portion b of the bed still
contains available Na-ion. Consequently, the
The spent regenerant liquor iiowing from this bed
contains Na2SO4 and K2SO4 as a result of the ex
juice leaving the bed is free of Ca but contains Na
change. After the auxiliary regeneration of the
ñrst bed with NaCl, and the H-cycle regenera
tion with HQSO». of the second bed have been
changer stage or bed the intermediate condition
completed, these beds are then in a condition to
of which is designated as C22. Originally this bed
be re-used in the saturation phase, that is, in the
was regenerated in the H-ion cycle whereby it
treatment of the juice, an intermediate condition
has adsorbed H-ion available for exchange, but
of which phase is shown in Fig. 4.
in the intermediate condition C22 the upper por 10
We claim:
tion c of the bed is saturated with Na and K-ion
l. vIn the ion exchange treatment of sugar
in exchange for H-ion yielded, while the lower
bearing
solution containing Ca-ions adapted to
portion d still contains H-ion available for ex
form with H2504 regenerant solution precipitable
change.` The juice leaving the bed is free of Ca,
K and Na, but contains the molar equivalent of 15 reaction products, and also containing cations
adapted to form with H2804 soluble reaction
these ions in hydrochloric acid formed as the
products, in which the solution is passed through
net result of this cation exchange. 'I'he hydro
a bed of organic granular _cation exchanger ma
chloric acid in turn can be replaced with its molar
‘ terial operating in the H-ion exchange cycle and
equivalent of H2O by means of treating the juice
in a subsequent anion exchanger station (not
regenerable with H2804 regenerant solution, the
and K.
The juice then enters the second cation ex
shown).
20
method for minimizing Ca-sulfate coating form
Fig. 5~ shows the regeneration of the two cation
ing in situ on such exchanger granules, which
exchanger stages or beds after the same have be
comprises the steps of conditioning the sugar
come exhausted due to the saturation of the iìrst
bearing solution prior to its treatment in the H-l
bed with Ca, and of the second bed with Na and
ion exchange material to eiîect removal of ,said
K. A suitable auxiliary regenerant solution such 25 Ca~ions by passing the solution through a bed o'f
as NaCl is sent through the ñrst bed in order to
cation exchanger material whereby the bed is
restore Na-ion therein- in exchange for Ca. The
saturated with Ca-ions from the solution in ex
condition of the bed, as shown in Fig. 5, is an
change for non-precipitable cations going into
intermediate'one and designated as C22. That is
to say, the upper‘portion e of the bed in that con 30 the solution, regenerating said bed with an auxil
iary regenerant solution containing in suitable
dition is regenerated with Na-ion, while the lower
molar concentration non-precipitable cations to
portion still contains the previously adsorbed Ca
exchange with the preclpitable cations in the bed
ion. The spent liquor :lowing from this bed con
whereby there is discharged from the bed spent
tains CaC12 as a result of the exchange of Na for
Ca. The intermediate condition in the regenera 35 regenerant liquor containing said precipitable ca
tions.
tion phase of the second stage or exchanger bed
2. The method according to claim 1, in which
in Fig. 5 is designated as C24. H2804 is the re
the auxiliary regenerant solution comprises at
generant solution whereby H-ionl are being re
least one of the alkali metal salts.
stored in the exchanger by way of the H-ion
3. The method according to claim 1, in which
cycle. In this condition the upper portion g 40
the auxiliary regenerant solution comprises a
of the bed is shown to have been regenerated
sodium salt.
with H-ion, while the lower portion h still con
tains the previously adsorbed Na and K-ion.
-
FRANKLIN N. RAWLINGS.
LOUIS un GEORG?.
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