I 104
T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol.
T.Sanderson, “A Study of the Variation in Weight of a Fifty-Pound Sack of Flour during Storage,” No. Dakota Station, Spdcial Bulletin 3 (1914), 14; “A Further Study of the Variation in Weight of a Fifty-Pound Sack of Flour in Storage,” Ibid., 3 (1914), 250. W. L. Stockham, “The Capacity of Wheat and Mill Products for Moisture,” No. Dakota Station, Bulletin 120 (1917). C. 0. Swanson, J. T.Willard and L. A Fitz, “Kansas Flours. Chemical, Baking, and Storage Tests,” Kansas Station, Bulletin a02 (1915), (Note p. 119). J. T. Willard, “Changes in the Weight of Stored Flour agd Butter,” Kansas Board of Health, Bulletin 7 (191 l ) , 9
CHANGES IN T H E POLARIZING CONSTANTS OF SUGARS DURING REFINING‘ By A. F. Blake ATLANTICSUGAR REFINERIES,LIMITED,S T . Received June 26, 1920
JOHN,
N. B.
I t is the purpose of this paper t o discuss the changes taking place in the relationship between polarization, true sucrose, and invert sugar during the refining of raw sugar, t o determine, if possible, the causes of these changes, and t o point out their practical significance. As pointed out by Dr. Brownej2 the percentage of true sucrose in a mixture of sucrose with pure invert sugar, consisting of equal parts of dextrose and levulose, will exceed the polarization a t 20’ C. by about three-tenths of the percentage of invert sugar. That is, s-P
= 0.30 I
where S represents the percentage of sucrose, P the polarization, and I the percentage of invert sugar. The factor will vary very slightly with the concentrations of sucrose and invert sugar, but a very small deviation from equality in the proportions of dextrose and levulose in the invert sugar will very greatly alter its value, because of the wide difference in t h e rotations of these two sugars. A value of (S- P ) / I above 0.30 indicates excess of levulose; a value less than 0.30, an excess of dextrose. Dr. Browne discusses the influence of temperature, maturity of cane, methods of manufacture, and length of storage of raw sugar upon the value of this r a t h , and mentions the fact t h a t in the process of refining its value is very materially reduced, and gives analyses of soft sugars and refiners’ sirup, in support of this assertion. EXPERIMENTAL P A R T
I n Table I is shown a n analysis of a cargo of Cuban raw centrifugal sugar of uniform quality and all one mark, together with the average analyses of soft refined sugar and refiners’ barrel sirup produced from it. These particular analyses .are selected for the purposes of the discussion because they are quite typical and because the refinery started melting this cargo following a shutdown from which practically no stock in process was brought forward, and melted this cargo exclusively for a considerable period, so that i t is quite certain t h a t the three analyses are interrelated. Dr. Browne’s observation of the reduction of the value of (S- P ) / I is very strikingly affirmed. 1 Presented a t the 60th Meeting of the American Chemical Society, Chicago, Ill,, September 6 to 10, 1920. a I n a paper entitled “Influence of Conditions upon the Polarizing Constants of Sugar Cane Products ” read a t the 56th Meeting of the American Chemical Socicty, Cleveland, Ohio, September 10 t o 13, 1918
12,
No.
II
TABLEI-ANALYSIS OF CUBANR A W CENTRIFUGAL SUGAR A N D OF SOFT REFINED SUGAR AND REFINERS’ BARRELSIRUP PRODUCED THEREFROM RAW SOFT REFINERS’ SUGAR SUGAR SIRUP ANALYSES WET Polarization a t 20’ C . . . . . . . . . . . 95.87 88.47 38.40 Sucrose Clerrret.. 96.42 88.74 40.60
..............
EX-WATERAND INSOLUBLE Polarization. 97.04 Sucrose Clerget.. . . . . . . . . . . . . . . 97.59 I n v e r t . . ...................... 1.27 Ash. 0.67 Organic.. 0.47
..................
.......................... .....................
IMPURITIES
Invert.. ...................... Ash ........................... Organic.. ..................... RATIOS Invert + Sucrose X 100.. Invert + Ash.. . . . . . . . . . . . . . . . . (S P)/I. . . . . . . . . . . . . . . . . .
......
-
52.7 27.8 19.5 1.30 1.89 0.44
93.41 93.70 3.71 1.31 1.28
47.74 50.48 28.58 10.11 10.83
58.8 20.8 20.4
57.7 20.4 21.9
3.95 2.83 0.077
56.6 2.83 0.096
The value has fallen from 0.44 in the raw sugar to 0.077 in the soft sugar and 0.096 in the sirup. The value of 0.44 is a little above the average. This ratio is subject t o wide variations, as shown by a summary of the results obtained on 3 2 cargoes from various sources. No.
Cargoes 8 6 10 2 6
From Cuba Cuba Demerara Demerara San Doming0
Time Received June-Dec. 1919 Jan.-March 1920 June 1919-Jan. 1920 Dec 1919-Jan. 1920 June-Oct. 1919
-Val.ue MiniCondition mum Deteriorated 0.08 New crop 0.44 Good -0.03 Deteriorated 0 . 4 8 Good 0.23
of ( e P ) / I Maximum Av 0.29 0.20 0.73 0 . 5 5 0.34 0.16 0.55 0.51 0.59 0.37
---
TOTAL-0.03
0.73
0.30
It seems t h a t new crop sugars have higher values than the remnants of the old crop, which in this case were in general more or less deteriorated, although in some instances deterioration may be of such a nature as t o increase the ratio. WAsHIxG-The first process of refining is one of affination or washing. The sugar is mixed t o a magma with its own sirup washings, purged in centrifugal machines, and washed with water. The only result is a separation into a high-purity washed sugar and low-purity washings. I t is hardly t o be supposed t h a t any change in the value of (S- P ) / I would take place here, though i t is possible t h a t it might differ somewhat in washed sugar and washings, since the impurities in the sirup are those of the molasses adhering t o the grain, and those in the washed sugar those in the grain itself. I n the latter the invert is lower and the organic higher. The analyses in Table I1 would indicate t h a t there is no great change of the (S - P ) / I ratio in t h e process of affining. The determination of the ratio with great accuracy is impossible in very high-purity material such as washed sugar, TABLE11-ANALYSIS OF
WASHED
OR
SUGAR
FILTERED SOLUTIONS OF CUBAN RAWSUGAR AND AND
.... .... .......... .... .... .... .......... .... ......... - P)/I*...............
Dry Polarization.. Clerget Invert.. ......... Dry Ash... Organic.
CENTRIFUGAL WASHINGSPRODUCED
THEREFROM Raw Sugar 96.37 96.91 1.20 0.62 1.27 0.45
Washed Sugar 98.77 98.98 0.43 0.19 0.40 0.49
Centrifugal Washings 78.05 80.56 8.35 3.62 7.47 0.30
since a trifling error in polarization or Clerget, say, 0.05 degree, makes a large error in (S-P)/I. The washings, too, being very highly colored, present some difficulties in a Clerget determination, but the
Nov., 1920
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
most approved methods were used and usual sources of error eliminated' as far as possible. DEl."ECATION-After t h e washing process both sugar and washings are defecated with lime and phosphoric acid a t a temperature of 180' F. and left slightly alkaline t o litmus. The concentrated, bone-black filter sweet water, or char water, and the concentrated bag-filter flush water, or scum water, are also thus treated and then filtered through bag filters. Table I11 shows no change for (S - P)/I for washed sugar TABLE111-ANALYSIS O F CENTRIFUGALLY WASHED RAW S U G A R BEFORR DERECATIONAND AFTER DEFECATIONAND BAG FILTRATION Before Afte? Defecation Filtration Brix .............................. 61.25 60.62 98.74 Dry Polarization a t 20' C.. . . . . . . . . . 98.67 Dry Sucrose Clerget., . . . . . . . . . . . . . . 98.81 98.89 Dry Invert.. ...................... 0.43 0.46 Dry Ash .......................... 0.25 0.23 0.5 1 0.42 Dry Organic.. ..................... (S - P ) / I . . ....................... 0.33 0.33
from the time of reaching the blow-ups until through the bag filters. Table IV, however, shows a slight reduction from the defecation for scum and char water, and n greater reduction for the centrifugal washings. OF Low TESTMATERIAL BEFORE AND AFTER DEFECATION Mixed Scum and Char Water Centrifugal Washings
TABLEIV-ANALYSIS
7
Before After Defecation Defecation Alkalinity a t 32' Be.. , (0,001 N Acid) 0.009 N Brix (Diluted and Fil40.70 37.50 tered). . . . . . . . . . . . . 78.67 78.85 Dry Polarization., Dry Sucrose Cleraet.. 78.87 78.99 Dry Invert.. .-. .... 6.24 6.37 4.72 4.80 Dry Ash . . . . . . . . . . . . . 10.17 9.84 Dry Or anic.. . . . . . . . . 0.031 0.021 (S Py/I,. ..........
....
...
.
-
.c___-
Before After Defecation Defecation 0.006N 0.023 N 32.50 17.08 78.83 10.68 3.01 7.48 0.16
30.40 77.53 78.39 10.55 3.13 7.93 0,081
In t h e latter case, t h e material after defecation is rather more than slightly alkaline, and a slight loss of invert sugar is indicated. Heating with lime, of course, is known t o destroy invert sugar, and doubtless the levulose is the ingredient most affected, thus reducing the value of (S - P j / I . From this and other analyses, however, i t is not believed t h a t any great portion of the decrease in (S - P ) / I during refining is attributable t o blow-up defecation. After use, the bag filters are flushed, in this case with hot water only, producing a light material known as scum water. The mud removed from the bags is diluted with water, limed, and heated t o a high temperature, and filter-pressed, yielding press water. TABLE V-ANALYSIS O F CENTRIFUGAL WASHINGS BEFORE DEFECATION SCUM WATER, A N D PRESS X'ATER Centrifugal Scum Press Washings Water Water Brix. ............................. 57.4018.20 5.15 0.014 N Alkalinity by Ca(0H)Z.. 0.004 N 0.010 N Dry Polarization a t 20' C.. . . . . . . . . . 78.56 79.68 67.38 80.38 67.38 Dry Sucrose Clerget.. . . . . . . . . . . . . . . 80.94 7.77 5.65 Dry I n v e r t . , 0.33 4.56 10.25 Dry Ash .......................... 4.10 Dry Organic ....................... 9.41 7.19 22.04 0.31 0.12 (S P)/I ......................... 0.00
............
......................
-
Table V shows comparative analyses of the centrifugal washings last on the bag filters, the scum water, and the press water. A decrease in t h e ratio is t o be noted, the decrease being again accompanied by loss of invert. I n the case of the press water, t h e invert has been practically all destroyed by the liming and heating, and, as would be expected, t h e polarization equals t h e Clerget, and (S-Pj/I is zero. AS only a small
I I O j
portion of the melt is handled as scum water or press water, however, we have t o look further for the main cause of the decrease of the ratio. TABLE VI-ANALYSIS
OF BAG-FILTERED MATERIALBEFORE A N D AFTER TREATMENT WITH FRESH 'BONS-BLACK ' hiostly Scum and -Washed Sugar- -Char W a t e y Before After Before After Treatment Treatment Treatment Treatment Brix. 60.85 57.85 56.70 Dry Polarization.. 98.77 99.17 86.95 91: ii Dry Sucrose Clerget.. 98.87 99.15 87.11 90.80 Dry Invert.. 0.47 0.31 5.91 5.11 Dry Ash 0.24 0.13 2.35 1.26 0.42 Dry Organic.. . . . . . . . . . . . . 0.41 4.63 2.83 Invert Per cent Impurities. . 41 .6 36.5 45.8 55.5 Ash Per cent Impurities. ... 21.2 15.3 18.2 13.7 Organic Per cent Impurities 37.2 48.2 36.0 30.8 (S--)/I ................ $0.21 -0.06 +0.027 -0.076
.................... ........ ..... ............. .................
BONE-BLACK FILTRATION-Table VI shows a change in (S--)/I on washed sugar filtered through boneblack, from 4-0.21 t o -0.06, and on low-test bag-filtered material treated with fresh bone-black in a laboratory It would seem t h a t test from + 0 . 0 2 7 t o -0.076. here is the real cause for the change in (S- P ) / I during refining. I n every test i t has been found t h a t in the case of the material first off the bone-black the polarization always exceeds the Clerget. Table VI1 gives progressive analyses of the various materials going on a bone-black filter and of roughly equivalent portions coming off. The value of (S- P j / I is greatly reduced on the first material, washed sugar, and progressively less so on t h e granulated sirups and char-filtered liquor following. The averages show a considerable loss for the whole operation. It is also t o be noted t h a t low material put on fresh bone-black, as in Table VI, suffers a large decrease in (S- P ) / I , but when put on the end of a used filter the ratio is but little changed. Another point of interest is t h a t invert is absorbed from first material and given up to later material, the whole operation resulting in no loss of invert. I n this test there appears t o be a slight loss of invert, but numerous other tests of like nature have shown a good balance, but always with the same transfer from first material t o later material. The significance of this invert absorption will be treated shortly. The same conclusions regarding the relation of char filtration t o (S--)/I are drawn from the analyses of three grades of soft sugar shown in Table VIII. The light yellows, boiled from liquor early off the char filters, show negative values for (S- P ) / I , the brilliants boiled from later liquor show positive values, and t h e darks still higher values. The average soft sugar of Table I, mostly brilliants with small amounts of light and darks, shows a value in agreement with Table VIII. The high invert per cent of impurities on lights is not because invert has not been absorbed, but because the other impurities, ash and organic, have been absorbed t o a much greater extent. Subsequent t o char filtration there appears t o be no change in (S-P)/I. The average value for all t h e material off t h e filters is not greater than t h e average value i n final soft sugars and barrel sirup. I n Table I t h e value for sirup exceeds t h a t for soft sugars because there is some light yellow, with its negative value of (S - P)/I, mixed into the average soft.
T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol.
I 106
TABLE VII-ANALYSES
MATERIALGOINGON
Washed Sugar
MATERIAL
...........................
Gallons. Solids Per cent of Total on. Brix. Alkalinity.. Color. D r y Polarization.. Dry Sucrose Clerget.. Dry Invert. D r y Ash Dry Organic. Invert Per cent Impurities.. Ash Per cent Impurities. Organic Per cent Impurities. (Invert iSucrose) X 100 Invert -I Ash
........... ............................... ........................ ............................. ..................
(S-
OF
............... ........................ ........................... ....................... ......... ............ ........ .......... ...................... P)/I .........................
13,860 50.54 58.85 0.003 41 0 98.56 98.59 0.46 0.29 0.66 32.9 20.7 46.4 0.47 1 59 0.07
.
AND
COMINGOFF
A
Granulated Sirup
No. I I
BONE-BLACK FILTER CharHeavy Filtered Char Liquor Water
Weighted Average
8,280 30.37 59.35 0.003 N 45.0 90.25 90.47 5.31 1.73 2.49 55.7 18.2 26.1 5.87 3.06 0.044
27,180 100.00 59.54 0.003 N 45.0 94.31 94.44 2.90 1 .05 1.61 52.2 18.9 28.9 3.07 2.76 0.045
Goinn on Filter
.... .... .... ..... ... .... ....
N
12,
3,600 13.91 62.45
0.002 N
45.0 91.59 91.75 5.09 1.38 1.78 61.7 16.7 21.6 5.55 3.70 0.031
....
.... .... ..*.
.... .... ....
.... ....
1,440 5.18 58.35 0.006 N 110.0 85.00 85.36 5.67 3.57 5.40 38.8 24.4 36.8 6.65 1.59 0.063
Corninn off Filler
MATERIAL Gallons. ...........................
...........
Dry Organic. ... Invert Per cent Impurities. .. Ash Per cent Impurities. Organic Per cent Impurities.. (Invert i Sucrose) X 100.. Invert i Ash.. (S-P)/I
.... .........
.
............ ........
Washed Sugar 10,660 38.83 59.55 0.002 N 1 .o 99.45 99.32 0.28 0.13 0.27 41 .O 18.5 40.5 0.28 2.21 -0.48
Mostly Washed Sugar 2,660 9.93 60.90 0.1002 N 5.0 97.78 97.68 1.50 0.31 0.51 64.5 13.5 22.0 1.53 4.79 -0.067
The boiling in vacuum pans does not affect the ratio, if there is no inversion. Inversion, here or elsewhere, would presumably increase the ratio by addition of true invert TABLE
VIII-ANALYSES OF LIGHT,BRILLIANT,A N D DARKSOFT REFINED
SUGARS
M 234 Lot R o .......... M 231 0 271 Light Brilliant Grade. Light Polarization at 23O C ......... 92.50 90.55 87.85 Sucrose Clerget.. 92.48 90.50 88.06 Water.. 5.20 6.35 5.25 Impurities ....... 2.32 3.15 6.69 Invert.. . . . . . . . . 1.32 1.96 3.23 Invert Per cent 48.3 62.2 Impurities ..... 56.9 -0.026 +0.065 (S P)/I.. -0.015
-
..........
0 621 Brilliant
M 197 Dark
0 614 Dark
........
90.00 90.19 3.50 6.31 2.99
85.55 85.96 4.10 9.94 5.02
85.00 85.47 3.40 11.13 5.52
.....
47.4 4-0.063
50.5 49.6 4-0.082 + 0 . 0 8 5
sugar with its normal value of 0.30. T h a t this is t h e case is shown in a n exaggerated manner by the analysis in Table I X of a table sirup made by deliberate inTABLEIX-ANALYSIS
OF A TABLE SIRUPMADEn Y INVERSION OF CHARFILTERED LIQUOR Brix ............................................ 81.25 Polarization a t 2 1.7 C.. 7.10 Sucrose Clerget.. 22.86 Invert 55.87 (S- P)/I 0.282
.......................... ................................ .......................................... .......................................
version of char-filtered liquor. (S- P ) / I is 0.282 or, as would be expected, almost up t o the theoretical value. h less exaggerated case is shown in Table X, where some char-filtered liquor was purposely TABLE X-ANALYSIS
OF CHAR-FILTERED LIQUOR BEFORE AND AFTER ARTIFICIALINVERSION, AND OF THE INVERTED LIQUORAFTER BONE-BLACK TREATMENT Before After After Char Inversion Inversion Treatment 57.80 57.55 Brix 60.00 88.96 88.15 D r v Polarization a t 2 1 C.. . . . . . . . . . 91.08 88.82 89.49 D r y Sucrose Clerget.. ............... 91.20 5.37 3.97 5.69 Dry Invert.. 6.03 4.36 6.4 (Invert iSucrose) X 100. 0.097 0.119 0.029
