Prelimer suspended solids can be separated. - ASSBT Proceedings

NORMAN~ LLOYD 1 , GARY GARCIA 2 , VINCE SALZMAN2, FABffiN CABRERA 3 ,
THOMAS CHARBONEAU 4 , and KENNETH STEWART 4 , I Brose Chemical Co, 2309
Lockhaven Dr., Colorado Springs, CO 80909, 2Imperial Holly, PO Box 468, Worland,
WY 82401, 3 Applexion, 264 avenue de Mauldre, 78680 Epone (France), 4Brose
ChemicaJ Co., PO Box 1506, Twin Falls, Idaho 83303 . Prelimer Suspended Solids Can
Be Separated.
Our work with cationic polymers as process addjtives to improve the quaJity of
processed sugar beet juices goes back several years. In 1991 the harvest conditions were
poor in several Rocky Mountain beet growing areas, particularly so at Hereford, Texas
where over half a million tons of beets could not be harvested nonnaUy. As they
struggled to harvest and process these frozen beets, they encountered considerable
difficulty with filtration of 2nd Carb juice with process capacity being seriously reduced.
Use of the cationic Mafloc 2009 improved 2nd Carb fiJtration and helped a great deal in
allowing them to process the great majority oftbe frozen beets involved. The polymer
continues to be used for the same purpose at several sugar plants when deteriorated beets
are encountered.
Since tbe cause of poor filtration was attributed primarily to dextran in the affected beets,
the idea was conceived that dextran elimination at the Prelirner would be helpful.
Carried a bit further, the idea became elimination of all suspended solids at the Prelimer.
Such elimination has been sought for many years. In past years plant scale testing has
been conducted in the U.S. (using proprietary technology) with some success being
achieved; however, the results have not been entirely satisfactory up to the present time.
Whether any European systems are in operation is not known. While our work was
started at the Hereford plant ofImperiaJ Holly, it was continued at a nwnber of other
plants including: the Scottsbluff Fort Morgan and Billings plants of Western Sugar~ the
East Grand Forks plant of American Crystal Sugar, the Renville plant of Southern
Minnesota Sugar, the Wahpeton plant of Minn-Dak Farmers Cooperative, and the
Worland plant ofImperial Holly_
Laboratory testing was conducted at each ofthe plants and, when possible, treatment of
all or part of the plant stream itself was undertaken. The primary obj ective of aU plant
tests was to produce a treated Pre1imer effluent that would be free of suspended solids
and would eventually yield purified thin juice (after main liming and 1st carbonation)
equal to or superior to the purified juice normally produced. All, of course, without
causing a reduction in plant throughput or an increase in plant sugar losses. To
accomplish this one of the most important results must be the ability of the plant to
handle the physical separation of all suspended solids generated in the Prelimer
operation. NormaJly this would mean that concentration of the suspended solids by
sedimentation must provide a small enough volwne with sufficiently good filtration
characteri stics that the existing filtration equipment could keep up without loss in slicing
capacity. Furthermore the wa hability of the filter cake must be such that no additional
sugar would be lost in the waste lime stream, which is now the di scard from the Prelimer
sludge filters instead of the 1 st Carb sludge filters. Because our testing was done in
87

plants that utilize the conventional separation of precipitated suspended solids after 1 st
carbonation, where sedimentation in a clarifier is fo llowed by fi ltration of the
concentrated sludge, testing of OUI system on a full plant scale required an extra piece of
equipment--another clarifier. With proper piping plant operators can gradually switch
filtration from the conventional processing to our new process wi thout additional filters,
but two clarifiers are needed during the switchover. The fonowing list of steps compares
the conventional process with our new Prelimer separation system:
Conventional ] st Carb Separation
l. Raw juice to Pre]jmer
2. Prelimer effluent to Main Limer
"J. MainLimer to 1st Carb
4. 1st Carb effluent to clarifier
5. Underflow to fi Itration
6. Overflow & filtrate to 2nd Carb
7. 2nd Carb to filtration
8. Fihrate to sulfitation
9.
10.
11 .
N w Prelimer Solids Separation
Raw juice to Pre]jmer
Pre]jmer effluent treated
Treated emuent to clarifier
Underflow to filtratIOn
Overflow & filtrate to Main Limer
Main 1imer to 1 st Carb
1 st Carb to clarifier
Underflow recyled to Prelimer
Overflow to 2nd Carb
2nd Carb to flitratlOn
Filtrate to sulfitation
Please note that it very well may be that double carbonation will not be necessary,
because ofthe elimination ofimpurities at the preli mer and the fact that the juice to the
1st carbonation is clear.
Whenever work was done at any ofthe sugar plants, the first order ofbusiness was to do
some lab scale testing. These tests were to establish the effectiveness of the polymer
additions at the glven time and place. All sedimentation tests were conducted using a
500 ml graduated cylinder. A well stirred sample was poured into the cylinder filling
same to the 500 ml mark. Ifany treatment was to be added to the sample it was
introduced into the cylinder prior to adding the juice sample (however, we found Ilttle or
no difference when the treatment was added afterward) The sampJe was then m ixed in
the cylinder using a coited wire stirrer that was passed up and down throllgh the sample
several times. After the stirrer was removed a stop watch was started and the time
requi red for the interface (between the sludge level and the clear supernatant) to reach
the various levels in the cylinder was noted and recorded (for instance, the 450 ml level.
then the 400 mllevel etc.). By graphing the time required versus the cylinder level one
can compare untreated settling rates against various treatments employed. Because of
the turbulence caused by stirring in the cylinder, a sma ll amount oftime is required to get
the interface ofthe sludge level established. This causes a curvature in the upper part of
the time versus interface graph. While this does not cause much of a problem in
comparing graphs, the turbulence effect can be eliminated by extending the constant
settling rate straight line of the curve back ~ard and moving the entire graph till the
extension passes through zero time and 500 ml. Three or four of the settling rate curves
may be superimposed on a single graph fo r easy direct comparison of treatments.
88

In very early \ ork we employed a simple gravity tiltration test. Number two Whatman
filter paper was used to assure best UI iformity ofth filt r medium. Wepo itioned the
filter fun n I and paper above a graduated c. linder. poured a specific volume of mi,'ed
Pr limer underflO\ into the fi lter and timed the collection of a parti cular volume or
filtrate. Thi method gave us easily comparable reo ults, but did not compare with th
plant filtration conditlOUs Therefore."\ e obtained a 0. 1 sq. ft. te~ t fi lter from the jmco
Company so that " e could more nearly simulate plant condition. TIle test leaf consisted
ofa circular flat plate with fi [trat channels on on side and a collection pipe protruding
from the other A screw on cylinder (the diameter of the filter plate) formed the filter
cake r ceptacle \ hich", when tightened against the flat plate, eal d a circle of filter cloth
between the cylinder and the plate.::. At each plant we used circles of fi lter cloth taken
from th type of filter cloth used at that plant on their rotary vacuum filters. To use the
test lea \ve attached a sufficientl. long. flexible plastic tube to the coli erion pLpe with
the other end of the plastiC tube cOIll1ected to a source of vaCULun the same as that lIsed in
the plant. TheIL by submerging the assembled test leaf with its circle of filter cloth in a
contai ner of stirred test ampJes we could appl the com parative vacuum for any given
ti me, collect the resultjng filtrate. and ha e information that could be dJ rectly related to
plant operations. The filtering b me (time test leaf submerg d) was the same as the time
any giv n part of the rotary filter cloth wa subm rged in the filt r tub 'Ne drained all
filtTate from the pia tic tube and mea w-ed the volume ther of. From th time and
vol ume informati on and knowing that the filter area of the leaf was 0.1 sq. f1 we could
calculate the fil tration effectiveness as gallons per minut per square foot of filter media.
This infonnation c uld then be c mpared wi th plant data.
Laboratory analytical info nnation on such important factor as purity, color, clarity, or
any other needed data was provided by the plant laboratory personnel. T heir information
\-vas inval uabl e to us. and \ e especially thank each and very person involved in
gathering this data for their h lp and cooperation.
All samples used in this v.:ork were taken directly from a plant stream and either treated
or 1 ft Lmtreated, as noted ill the text hereof. All were taken as gr b sample and
processed as quickly as possible to avoid spoilage or excessive temp rature drop.
Our first experience \ th addition of the cationic polymer Mafl oe 2009. was in
December, 1992. Grab samples ofPrelimer effluent (treated in the Lab) reacted
favorably up to 30 ppm in both ettlins and filtration tests (using the simple gravity test
procedure. \ e did not ha e the imco t st leaf at that time). The 30 ppm addition is the
limit allowed by the FDA at 10 percent sugar content in the juice. Addition f the 2009
to samples of 1st Carb effl uent gave similar Improvement in settling and filtering. It was
also noted that addition of a small amount of anionic polymer (Mafl oc 834) gave a
synergistic boost.
We were able to treat the plant Prelimer at 20 to 30 ppm for about a day and a half.
During that period then; was the usual mechanical problems that seem to haunt such
89

tests. The variability in operating conditions and the short test time, along with any
changes beet quality and/or testing variations, resulted in enatic result . At times it
appeared that there may have been improvement in settling and filtration, but at ti mes no
improvement was indicated. The plant personnel did not notice any adverse effect of any
kind they could contribute to the test. At any rate we were encouraged by the results.
Over the time frame from the first tests at Hereford in 1992 until the present a numb r of
tests were made at several beet sugar plants: Imperial HolJy Sugar plants at Worland
Wyoming and Hereford, Texas ~ Western Sugar Co. plants at Scottsbluff, Nebraska,
Billings, Montana, and Ft. Morgan Colorado' American Crystal Sugar Co. plant at East
Grand Forks, Minn esota ~ Southern Minnesota Sugar Co. plant at Renville, Mi nn so t~
and Minn-Dak Farmers Cooperative plant at Wahpeton, North Dakota. At Billings, East
Grand Forks, Renville, and Wahpeton only laboratory testing was conducted. Plant tests
were run at all other plants listed, most tests being of short duration (a couple of days or
so). Also, most ofthe tests were only involved with polymer treatment at the Preli mer
and evaluation of the settling and filtration qualities of the resulti ng Prelim r effl uent.
In order to properly evaluate the improvement in pJant operation realized from the
Prelimer treatment it is necessary that the full plant stream must be treated with all of the
suspended solids removed therefrom. To accomplish tIllSthe plant must be capable of
settling and filtering both the Prelimer effluent and also the 1 st Carb effluent. The plant
will nonnaJly run with separation of 1 st Carb soLids, but must be able to switch over to
separation at the Prelimer for the test period. If the plant personnel were willing to risk
starting out with and using the polymer system, only separation equipment at the
Prelimer would be needed. However, that is a risk that few would wish to take.
At any rate, to properly test the polymer technology, tRe plant needs the capability of
settling suspended solids both at the Prelimer and 1st Carb--usually a clarifier, though
other equipment could be utilized. The plant would al so require the capability of
switching on the run from filtering concentrated 1st Carb sludg to filtering concentrated
Prelimer sludge. Since there will continue to be suspended solids generat d at 1st Carb
when the solids are settled and remo ed at the Preiimer, disposition thereof is requir d.
Cone ntrated sludg from 1st Carb couJd either partially or wholJy sent dire tly to the
fIlter supply tank (for Prelimer sl udge) or recycled to the Prelimer to provide seed
crystals and bulk for improved settling and filtration. The latter option is sur Iy the
better, especially when lime addition is cut back to decrease costs. Witb th vast bulk of
precipitable material having been removed from the Prelimer effluent, particular! the
fluffy and sticky colloidal types, about all that is precipitated in 1st Carb is rather pure
calcium carbonate crystals having excellent surface characteristics to help gi e good
settling and filtration. The volume of recycle sludge from 1 st Carb to the Prelimer
should, of course, be minimal.
In all testing at the various plants we consistently found that the use of cationic Mafloc
2009 improved both the settling and filtering characteristics of the suspended solids in
Prelimer effluent. Because of the similar results obtained at each plant, we will no
90

include results from each plant. The data we sho\ \ ill be typIcal From the total
information gathered we have been able to come to severa l general conclusions The
fo llowing list would be incl uded :
1. The addition of cationic pol) mer, MafIoc 20 09, to Prelimer j uice sjgniticantly
im proves both the settling and fi1terin~ characteristics of be suspended solids therem.
2. The brreater the amount of 2009 added the greater the improvement realized.
This relationship is good to at least 300 ppm o f added polymer (ppm on t tal j uice). The
limit of addItion established by the FDA is 15 ppm based upon the amount of sugar in the
juice. Tbis limit translates to 30 ppm on juice \: ith 10 percent sugar content. If the sugar
content is higher or lower, the fDA lim it is increased or decreased proportionally . Sinc
normally the sugar content is well above 10 percent, we chose to use 30 ppm as an
arbitrary li mit to stay well ithjn the allowance. Should the uti lization become
commercial, it \ ould behoove the plant operators to monitor and adj ust the addition as
the sugar content changes, because the greater the addition the greater the effect.
3. The reaction of the 2009 with the soli d particles is not instantaneous We
found that in Lab tests at least 2 minutes reaction time was needed to get conSIstent
results in lab ratory analy es.
4. The point of addition of polymer is important. In plant tests we tried ceU ], 3,
and 5 in the Brieghel-M ull er prelimer. Becall e of the short duration of all test, we
could not determine the oprrmurn. We e entua lly selected Cell 5 as our preferred point,
since this point gi ves plenty of time for reaction, all particles to be settled are fully
developed, and the results obtained are good. Nevertheless, we believe that we do not
necessarily have the optim um poi nt of addition established.
5. Usually, but not al wa s, addition of small amOLmts of anionic polymers had
ad erse affect upon the settling and filtration of Prelimer suspended solids.
6. However, a si gnificant synergistic boost to the improvement achieved by the
addition of cationic Matloc 2009 was realized when 2 to 5 ppm of anionic polymer was
also add d. here appeared to be no clash or neutralization caused by the unlike charges
on the catio nic and anjonic pol lers.
7. AniOniC polymer Applexion Flo Cap 3 is b~ far the best anionic additive that
we have used The combined results are o ften phenomenal. On occasion I have seen
settling rates too fast to be able to get good readings. The reaction of this polymer
appears to be essentially instantaneous.
8. With removal of the suspended solids at the Prelimer and the resulting solids
generated at 1st Carb being white, nearly pure calcium carbonate we believe that there
would no longer be a need for double carbonation. The alkalinity could be taken directly
to the m111imumlime salts at 1st Carbo Brief testing of this on the Lab scaJe seemed to
verify the premise; however, we have not tried this at the plant level. 2nd Carb gassing
and 2nd Carb filtration could be eliminated with 1st Carb clarifier overflow and filtrate
going directl" to sulfitation and thin juice.
The following Table (Table 1) provi.des typical information regarding the effect ofthe
polymers Matloe 2009 and Applexion Flo Cap 3 upon the settling rates of the suspended
solids in the Prelimer effluent
91

TABLE 1
THE EFFECT OF POLYMERS ON SETTLING RATES
Polymer Additions in Parts Per Million
30-2009 30-2009 30-2009 30-2009
(aIQ n~ ) 5 FC3 +1 FC3 +2 Fe3
30-2009
+3 C3
Sludge L vel
Milliliters
450 38 sec 8 sec 11 sec 8 sec 7 sec
400 62 14 l8 12 12
350 87 18 25 . 16 16
300 111 2J
"")
j", 20 20
250 137 24 39 24
")"
L-'
200 26 49 32 30
175 67 46 41
150 29 108 76 71
First note that no untreated settling rate is presented because the floc formation and
characteristics were such that no sludge-supernatant interface could be determined.
Sometimes fairly decent settling rates for the untreated effluent could be measrrred, but
quite often the mixture fail ed to clarify in a reasonable length of time. There are some
interesting things demonstrated by this table. For the sample treated with 2009 alone it
took over two minutes to settle to the 250 mi lliliter level; however, in most clarifiers the
residence time is at least 30 minutes. I have seen 1st Carb settling rates no better than
this. But look at the rates for those samples treated with both the 2009 and the FC3. in
less then two minutes all had settled to the 150 level with the 2009 plus 5 ppm FC3
reaching that level in less than half a min ute. All of the combinations shown in the table
gave excellent settling. Some interesting things show up in the data. For instance, the 2
and 3 ppm FC3 treatments start out better than the 5ppm, but notice that toward the end
the 5ppm level proves best, as would be expected. As mentioned earlier, the turbuJence
from mixing has to subside so that the solid particles, which are going in all directions
when mixed, can start their downward motion. Only a second OT two is involved
initially, and, as fast as the settling proceeds, an error ofone second in taking the read1l1g
is quite possible. The reading at the 175 ml level for the 5ppm treatment is absent,
because in changing from the 50 ml distance to the 25 ml the reading was missed
entirely. These rates are among the best one can expect, and don' t forget that j ulce
quality and effectiveness of plant operation will affect the rates.
We believe that the best information available upon which to j udge the polymer system
with removal of the suspended solids at the Prelimer is that taken at the Worland plant
during the 1997-98 campaign. Two different test periods ere run: Monday (day ending
at 8:00 AM Dec. 9 till Fr iday (day ending Dec. 13, 1997) and Monday (DE Jan 13 ) till
Wednesday (DE Jan 22, 1998). The entire plant stream was treated at the Prelimer with
30 ppm cationic Mafloc 2009 introduced into the 5th cell of their Brieghel-Muller
Prelimer followed by 2-5 ppm Applexi on Flo Cap 3 anionic polymer added to the
Prelimer overflow trough. Each switch from nonna} processing with nonsugar removal
92

from 1 st Carb ffl u nt to pol) mer proce sing v ith nonsugar removal from the Prelimer
ef1luent was masterfully handl d by the Holly personnel with littl e upset ca used by the
switchover The (i !lowing positi ve statements can be made about plant operation during
testing:
J. T he settling: of the Prelimer sludge in the old Don tank caused little or no
problems as far as clari( o f the rtlO\i was concemd.
2. Plant personnel stated that with the pol_ mer . stem on stream they had better
operation w ith easi r control both on the remainder of the beet end and on the sugar end,
3. With tb principal nonsugar solids ha ing been removed at the PreLlmer, the
precipitate at 1st Carb did, indeed, turn white indicating that the solids consisted of
relati ely pure calcium carbonate--ideal for recycle to the P relimer.
4. To ee whether or n t lime usage could be reduce plant personnel c ut back on
the lime introduced to the Mainl imer--at least 112 for a period of time, 0 adverse
effects could be noted when this was done.
The only real problem encow1tered was tbe illability of the rotary vacuum filters to
handle all the sludge generated at the Prelimer clarifier (the old DOfT tank), Part of the
time they did OK, but th y fo ught this station most of the time, This, of course, caused
excessive los of sugar in the Iime waste, a serious economic problem. The filterability
of the generated sl udge was frequently monitored L1si ng oLlr E imco fi Iter leaf to test the
relative rate of filtration. Throughout the test p riods our Lab tests indicated that the
filtration rate should have been sati sfactory~ - at one period during the run we got Eimco
test Jeaf filtering rates that \vere almo t lll1beJ ievably good; nevertheless, the plant filters
could not keep LIp. One problem V'ias located: Filter leaf tests howed that a much better
filtration rate was fo und for the et11uent stream directly out oftbe PreLimer (before t he
transfer pump) as compared vvith the rat for the feed stream to the fi lter units (after the
transfer pump). S mce a high speed centrifugal pump was used to transfer the effluent
from the Prelimer to the filter supply tank it was apparent that the fraf,rile floc particles
were being damaged by the shearing action of the pump. Replacement ofthat pump with
a variable speed pump helped, but did not sol the problem. It appears evident that
special ha ndling of the eftluent is needed, Table 2 belm shows a comparison of filter
leaf test rates before versus after the high speed centrifugal pump and the improvement
that was made aft r t he variable speed pump was installed.
TABLE 2
LAB FfLTRATION OF PREUMER SLUDGE
High Speed Pump 12111 /97 Variable Speed Pump 12/12/97
Beror Pump After Pump Before Pump After Pump
Vacuum (nun Hg) 18 20 20 20
Milliliters Filtrate 195 100 160 125
GPM per sq. ft 0.34 0,18 0,28 0.22
Cake thickness (mm) 16 4 9 6
93

Note that with the high speed pump the filtrate recovered is nearly doubled when
filtration is ahead of the pump. 1t will also be seen that four times as much susp nded
solids were removed. This is surely strong evidence of degradation of the fragile floc
particles by the shear ofthe high speed centrifugal ptunp. With the variable spe d pump
significant improvement is shown. Still, the filtrate volume is 28% greater before the
pump, and the solids removal is 50 percent greater. The evidence indicates that the
gentlest possible handling ofthe effluent is imperative.
We had one opportunity to check out our theory that, with OUT polymer separation of the
suspended solids at the Prelimer, double carbonation would be unnecessary. We
obtained a large sample ofthe Mainlimer effi uent to 1 st Carb and batch carbonated tl e
sample in the laboratory. As the batch carbonation pro ceded, samples wer removed for
analysis. The pH, Iimesalts. purity. and color was detenn ined for each as shown in the
following Table, Table 3.
TABLE 3
BATCH CARBONATION OF MAfNLIMER EFFLUENT
pH UMESALTS PURITY COLQR
11.9 0. 194 43 L
11 .2 0. 11 ] 93.2 183
10.7 0. 068 92.7 83
10.3 0.064 93.4 91
9.9 0.043 93.2 63
9.4 0.063 93.2 70
Since this is infonnation from only a single laboratory sample, we surely cannot claim
any proof of anything. We can, however say that the data give an indication that we
could indeed eliminate the normal double carbonation. The nonnal 2nd Carb pattern of a
minimum limesalts is indicated, although at a pH of 9.9--higher than the usual 9.2-9.4 or
so. The purity a-ppears to be essentially constant, as it should be with onJy minimal
elimination ofnonsugars. And the color pattern is also about normal. We e en got the
minimal color at minimum limesalts in the test. Hopefully the premise ofthe single
carbonation will soon be resolved at the plant level.
Using assumptions that I felt were reasonable, I made something ofa quick economic
analysis which indicated that, despite the very poor lime waste losses, the periods of
testing may well have been profitable. Obviously, the polymer technology will never be
adopted until good profitability can be demonstrated. 1 would li ke to see some of the
plant people study the economjcs thoroughly. In my opinion tie potential for this
technology is great. It only stands to reason that nonsugars, particularly the fluffy, stick),
ones should be removed from the process stream as quickly as possible. Removal at the
Prelimer is at the first processing step.
94

So. what then remains to be done In order to prove the worth of the technology. I feel
that the tests at Worland in 97-98 show that only a little better filtration i required. A
mode rn automated plate and frame membrane filter station should do the u'ick Just one
supplemental fi lter \. ould do it at Worland, aSSllmll1g that th xtra DOff clarifier is not
dism antled. How much capital money would that tak e') At most other plants a second
clarifier would be needed. unl ess so meone is willing to take the big risk of committing to
the technology completely--such ri ks ha e b en tak en Some improvements can, 1
believe, be made to improve the 97-98 Wo rl and results. For one, it is the volume of the
sl udge that genera lly causes fil trat ion probkms B cause of the most excellent settling
obtai n d at Worland, perhap el os r and more positi ve control orthe sludge volume
could do the tnck. Concentration to 20% ufthe original volume was realized at
Worland. but what was the average percentage--30%-40 o ;o'> Reduction of those vol umes
to 20% reduces the volume to be filtered by :2 '3 and 1/2. How low can ( ne go'> Can one
get to 10%, or is even 200,/0 too thick. They found out at Worland that it can get too thick
when the DOff agitator stuck and an arm was broken \ h-=:n they restarted. A good look at
this area might yield good returns. Then there is Matloc 2012, the same polymer as 2009
but hav1I1g a higher average molecular \veight. Early Lab tests indicated that 2012 was
Just as good and maybe better than 2009. Tb 2009 has been recommended al l along
because it is a liquid that can be directl y metered by pump--the 2012 is more viscous and
doesn ' t pump well. I owever, at Worland thin juice was used to dilute the 2009 before
introduction into the system Such measure might show 2012 superior to 2009. At least
this should be checked out.
Then , looking farther 1I1to the future, ultrafiltration has shown more promise of late. Is
this or other new membrane technology out of the questIOn? It WOULd seem doubtful that
raw.i uice can ever be used in any membrane technology--but how about clarified
Prelimer.i uice')
95

Note that with the high speed pump the fi ltrate recovered is nearly doubled v hen
filtration is ahead of the p ump. It will also be seen that four times as much suspended
solids were removed. Tbis is surely strong evidence of degradation of the fragile tl oc
particles by the shear of the high speed centrifugal pum p. Wi th the variable speed pump
significant improvement is shown. Still, the fi ltrate olume is 28% greater before the
pump, and the solids removal is 50 percent greater. The evidence indicates that the
gentlest possible handling of the effluent is imperative.
We had one opportunity to check out our theory that, with our polymer separation oftbe
suspended solids at the Prelimer, double carbonation would be unnecessary. We
obtained a large sample of the M ainlimer effiuent to 1st Carb and batch carbonated the
sample in the laboratory_ As the batch carbonation proceded, sampl s were removed for
analysis. The pH, limesalts, purity, and color was determined for each as shown in the
following Table, Table 3.
TABLE 3
BATCH CARBONATION OF MAINLIMER EFFLUENT
pH LlMESALIS PURITY COLOR
11.9 0.194 43 1
11.2 0.111 93.2 ] 83
10.7 0.068 92.7 83
10.3 0.064 93.4 91
9.9 0.043 93. 2 63
9.4 0.063 93 .2 70
Since this is infonnation from only a single laboratory sample, e surely cannot claim
any proof ofanything. We can, however say that the data give an indication that we
could indeed eliminate the nonnal double carbonation. The nonnal 2nd Carb pattern of a
minimum limesalts is indicated, although at a pH of 9. 9--higher than the usual 9. 2-9.4 or
so. The purity appears to be essentially constant, as it should be with only minimal
elim ination of nonsugars. And the color pattern is also about norma l. We e en got the
minimal color at mini mum limesalts in the test. Hopefully the premise ofthe single
carbonation will soon be resolved at the plant level.
Using assumptions that I felt were reasonable, I made something of a quick economic
analysis which indicated that , despite the very poor lime waste losses, the periods of
testing may well have been profitable. Obviously, the polymer technology will never be
adopted until good profitability can be demonstrated. I would li ke to see some of the
plant people study the economics thoroughly. In my opinion the potential for this
technology is great. It only stands to reason that nonsugars, particularly the fluffy, sticky
ones should be removed from the process stream as quickly as possible. Removal at the
Prelimer is at the first processing step.
96
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