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Ion Exchange Process for Beet Sugar RefiningI. Purification of Beet Diffusion Juice

G. ASSALINI AND G. BRANDOLIRece ived to?' publication ;J IJ,-if 29, 1960

Before describing the technique known as the Assalini"A" Process, it is advisable to summarize briefly the conven-tional method for extracting sugar from beets as practiced inmost of Europe. The procedure is outlined in Figure I . Europeanpractice differs chiefly in that a raw beet sugar is produced. Thissugar is remelted and passed through some decolorizing materialand finally crystallized to obtain a refined sugar meeting thespecific chemical and physical requirements of the particularcountry. As in the U.S., the greater demand in the Europeanmarket is for refined sugar.

In the past 10 or 15 years, ion exchange resins hav e arousedconsiderable interest in the sugar industry in genera l, inasmuchas this technique showed considerable promise as a new methodBEET SLICES

DIFFUSION

Figure I .-European beet sugar process.

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342 JOURNAL OF THE A. S. S. B. T.of purification which could be capable of augmenting crystallization as the purifying technique. As a first approach, the application of ion exchange resins was investigated either for thepurification of thin juices to obtain greater sugar recover)' or topurify the molasses to recover the sugar which is otherwise uncrystallizable.

In large measure, the application of ion exchange resins fordeionization has not yet yielded the outstanding results originallyhoped for. The reasons for this have been many and th e difficulties might be summarized as follows:Thin Juice Deionization

vVhen using conventional deionization for the purificationof thin juice , it is necessary to cool the juice from 90 C. downto 10-15 C. wben using a strongly acidic cation exchange resin.This is necessary, of course, to avoid serious inversion of thesucrose during and immediately after the passage of the juicethrough the bed of cation resin in the hydrogen form. Inversion.can be controlled by use of a carboxylic cation exchanger. Additionally, when using strongly basic quaternary ammoniulllanion exchangers, it is necessary to cool the juice to flO C. orbelow to avoid undesirably high degradation of the functionalgroups. "While heat losses may be kept to a minimum, a heatexchange installation adds significantly to the capital investment.

Needless to say, all such expenses both for new plant andprocessing costs must be borne entirely by the additional sucroseextracted beyond that for the conventional method and mustalso cover the value of the molasses no longer produced.Molasses Purification

Ion exchange installations for purification of molasses wouldnot require special cooling since these syrups could he treatedduring the off-season. The major problem encountered ii1 thepurification of molasses is that of dilution. In fact, for the deionization of molasses, it is generally necessary to make successivedilutions. First , the viscosity of the molasses must he reducedby dilution from the point of view of lowering the concentrationof non-sugars S'O that the ion exchange operation is more easilycontrolled. Second , the sligar must be rinsed from the columnsafter exhaustion which entails additional dilution. Because of thehig"h non-sugar content, the cycles are relatively short and thesweetening-on and sweetening-off portion of the cycle becomes aLIl-i2"e percentage of the throughput.

In an attempt to simplify the conventional sug"ar recoveryprocess along with increasing the quantity and quality of sugar

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VOl , XI, ] \ 0 , 'I , 1961

decided of diffusiollmeans or \\'ith the elimination 01

the s t a f 4 e ~ of deiecaliol1 ill lilt:" (,(mventional process, rowanjtlils end. :1 series of were performed. initially illsmall columlls on ju and later ill a pilol plant capableof processing IRO gallons of d iffusiol1 juice pcr cycle, , \ sci lema I i(flow sheet. or ! II is planl is shown in Figure :.!,

of Assalini HA" Process to beet sugar

The ScllCI1W or this process could be summari/,ed as I'ollo\\'s:First

Thistilc measuring hasic anion ex

II This resin01' I as Amberlite JRA40IS or,

The mineral salts present arcII normal iOIl with the ion or the

Zl1l1011 and the ('(JIlye,:rsio[] 01 tile cation to its corresponding

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3[1 lI.;'>.AL OF l I l l : A. S. S. l l . T.hydroxide. Tile dissociated;the pI! due toALHtllJ."Lthe Tile01 the reaches aresin column

of seriolls inversion.Second Stage

(Chemical treatment and juice, whichhas already been panly defecated treatment,is subjected to :t chemical treatment. witiJ an salt whichis able to form a 'floc," and t.hus further defecate and decolorizethe juice. This particular oJ thelarge number of in order tosuitable salls for the Hoc formation which was optimum [romthe point of vie\\ or anal and economic requirements. It was fOlilld that a most eHkiellt flocculation or the or-ganic substances present, with decolorizalion, could be ohtained using a aillminulllsulfate. This treatment llIust be effecteda pH of 5.7 must be obtained to form theHoc. This pH \alut' is optimum from tbeeasiest filtration and minimuminum suUate into the whichthe ash content. Even undn thesetion is rather difficult andcan be obtained

H for ite\"(:'11 al

0/ calcium chloride I"or litis llocculatlOll was als()Tbis has s:,iven vcry guod resulLs f1011I the of

and economy. In tllis case. the juice !rom tile firstcolumn i . ~ lrc;Jted with a solution of calciumI Llw beel juice uncler . it , \ " a ~ found

thal optimum defecation was reached when a Cjllan! ofcalcium chloride ('(Illal to abollt O . O ; ) ( : ~ i or juice was employed.Flocculation was excellent as 11";(, the decolorization. \101 eover.the filtration of the suspension was casier than that rcsulhom tht' ;! lUl1linUIl1 slllfate treatment. : ' \aturalh, tiledefecated in this way undergoes a further i n c r e a ~ e inHmn'ver, it is necessary to avoid using excessin: amounts ofcalcium chluride hecause of the ol)\iolls increase in asll contenlwhich would result from this vcry soluble salt. Ecunomical

http:///reader/full/lI.;'%3E.ALhttp:///reader/full/lI.;'%3E.AL

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VOL. XI. :'\0. 1. 1'lGIthe use of calcium chloride ,vas more desirablethan the aluminum sulfate treatment because of the small

I t was found that sulfate is the salt \vhich theresults from the industrial of Vlew

from the Yiewpoint of lowest cost. amount ofcalcium sulfate which proved to he on the

JUICe was O.fl to 0.4(1;) baseel on juice. .\delition ofthe calcium sulfate was done from a of calcium sulfate.rhe addition was made to a of ~ ) , n . The final Tile

of the prewoule! the lise or thickenersfactory and the filtration or the thickened

slurry diHiculties.Orc! sand filters lJa\e been oyed lor these filtrations

since were found suitahle. It should be noted thal.in the case of the calcium salts, the juice does not reach an acidic

since the formed after the aniollicresin in the stag-e remain either unchangedor are only cOllverted to t he corresponding- sn Ifatf',Third

After the filtration indicatedamounts of soluble minerals andto complete the puriheation andthrong'l! two further beds of ionporous anion exchang-e resin in theAmberlite IRAA02, and the second is a acidic cation exchanger in the /\mberlite IRC-50. Afterthis two-bed iOll, the juice has a very hig'h , is ,irtually colorless and yields equivalent in to theproducts achieved the process used in as (ksnibed

this final ion treatment, the pH never fallsbelow 7 but it is possible to a hnal juice with a pHvalue bv the level of the AmherliteIRe-50,' However, this was found to beentire investig-ation. Since the carboxylic cation ISits consumption lor suHuric add is onlyslightly h theoretical. \Vhile the use 01 a strong-I)'acidic cation resin a higher purity with the removalof betaine, this su wOllld natura!!y rise tocant InverSIOn.

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OI 'HIE S, S, H, C[.

The a1110n Hl the fi.rst witllthe excess canstic recovered trol11 the dillon

in the third This lechn is important,the of view of economy smce it permits a

111 the deiul1l1.aLionslage, ",hidl maximum lile exccss hydroxideion can he utilized in the lirsl to hringabout Ihe necessary pH rise.from rile sec()nd anion cOlluins : lva l inus sod iUIII sa Its in add i tioll to lhe c x c e ~ s which ' iCnTS as r l le actual rcgenerant lor the lirst anion exchangcr.These sodium salts sene to remove rile great hulk (;)1 tilc orgallicIllaterial adsorhed the firsl anioll exchanger which treats lhedilltlsioll juice

The anion ill tllc first need !lot be regeneratedSIllCT e\en il all oj the salts II I the diffusion

converted to the conespondlll)4 thne isincrease in Iy and the pH to a point stich that

Aocculalioll, either with aluminUill or cakinm suliat IShrou)4ht ahout and is quite efficient.~ \ s the analytical and economic data obtained from

lhe various experiments, the 1'011 ~ u m m a r i e s i n d i c a t t ~ theresults obtained using tile process described above.

lYe the anal dala used for the calculation o( tech11 lea I and econOlll icas the sucrose andsugars. The and extractabilities 'I'ere obtained by rneansor direct These resul \Iilh calculations made lormula.

Tahle J.-;\nalytit"aI Data on Assalini "A " Prouss.

regeneration

1 effluenl

10

a

a sol ids halance as

Final juic('Diffusion Juice ,; A ~ ' Procc;

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VOL. Xl. 1\0. 4. 19liincrease ill the purity due to the ren10yal of volatile llonduri evaporation. This resulted in a slight decrease involatilils ,1.92 "U.'ut: ; / 100 lbs. bt'cts: \CI Cost 2.72 n:lIt:-s IOU Ill", hce[sProcessing Co:o;t Pound Sligar (.alllcd

of in ' \ f o [ a ~ s { ' $ Hut ProdHcedCost of Sugar Cained :),(,;) (en15/lb.

S l l c r O S t _ - t / ~

Losses up to I j me proc('s'\ """,,,,- , ' . Ri'"in and mtral iou 1()s'iCS SlIcnhC jn j l l i c l ' - ~ - ~ ) P u r i t ~ - " " ( , ) i ; ' rota! llOIl-'iugar

SUCf{)SC il l rnol

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348 OF THE ;\ . S. S. B. T.Economics

Raw and RefinedThe economics of the "A" Process have been evaluated in

Table 4. Here again the values are hased on Italiall sligar practice.Production of Refined

From a syrup With a of 97.5 to and o.r) Stammerunits per 100 solids. at least of refined sligar is obtained inEurope directly from tbe first massecuite. The second and thirdproducts w()uld be sent hack to tht' . T a k i l l ~ the cost ofrefining at O.7:) we havt'.

T.lhk 5 . -Product io l!-Udil led Sugar.9.4 cents

\ssalini "A " Process

in gtor each lb. of additional OJH cClIts!lb.

The cost for a plant tohas been estimated ill Table fi.agam bct'll based on European2000 lOns of beetsThe economic eva I dayhas

Tahle 6 . ~ P l a n r Economks- .. t\)) } > r O f ( ' S ~ . Basis-2.000 tom heet) per tla)Installation: :SZlO,OOO-RLsins

:-d t:1,OOO-1'.qlliplllLllt

Amortization Rate ;) l.Hnpaign;;-