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?.