209
ANALYTICAL EDITION
March 15, 1942
Summary TABLE IV.
CODEPOSITION OF IRON AND OTHERMETALS
Weight of Total Weight of Second Weight of DimethylglyMetal Added" Fe Added oxime Test (SHa)2S Test Deposit Error Gram Gram Gram Mg. 0.0126 S i 0 . 1033 Positive Segative 0.1163 - 0.6 0.1116 0.1 0.0084 K i 0.1033 Negative Negative 0.1114 0.3 0.0084 pu'i 0.1033 Segative Negative 0.1077 f 0.2 0.0042N i 0,1033 Segative xegative 0.1091 c o Segative 0.1037 - 6.4 0.1091 C O o.io33 Negative 0.2114 1.0 0.1091 Co 0.2066 Negative 0.3154 0.3 0.1091 Co 0.2066 Negative 0.3159 f 0.2 0.0218 hlo 0.1033 b,c Black 0.0950 -30.1 0,0109 110 0.2066 c Kegatire 0.2181 4- 0 . 6 0.0109 410 0.1033 c,d Negative 0.1144 f 0.2 0,0075 W 0.1033 C,O h-egative 0.1072 - 3.6 0,0075 W 0.1033 C,O Negative 0.1068 4.0 4 Second metals added as Ni804, COSOI. Na2JloO4, and NazN-04 standard solutions to ferric alum before addition of phosphate. Electrolyzed: b 140 d 75, and e 60 min., respectively. e Used 10 mi. of stock phosphate.
-
-
..
-
cobalt alone. Ammonium sulfide is still only a test for iron;
c p to 10 mg. of molybdenum are quantitatively codeposited with 100 mg. or more of iron. Amounts of molybdenum above about 20 mg. depolarize the cathode and prevent complete deposition of iron. The range between 10 and 20 mg. of molybdenum in 200 ml. of electrolyte \vas not examined. In this range, the transition from the platable to the depolarizing concentration occurs' It might be to examine the from a possibility Of plating trolyte containing a very low concentration of molybdate.
Iron can be quantitatively determined as metal by electrodeposition from a hot complex ferric ohosohate-ammonium carbonate solution at a h g h - current density without stirring. The method is accurate and reasonably fast. The highly sensitive ammonium sulfide test is available to prove completeness of deposition. The method may be applied to low manganese iron ores without removal of hydrochloric acid. Small amounts of nickel or molybdenum are quantitatively codeposited with large amounts of iron, and cobalt with a t least twice as much iron. Tungsten must be absent. Large amounts of chloride] sulfate, and phosphate do not interfere. Sitrate and all strong oxidizing agents must be absent.
Acknowledtzment
Literature Cited
s., and Dales, B,, Ber., 32, 64 (1899).
(2) Brand, A,, z. anaz. Chem., 28, 581 (1889). (3) Moore, T., Chem. News, 53, 209 (1886). (4) Willard, H. H., and Furman, N. H., "Elementary Quantitative Analysis", 2nd ed., pp. 194-5, New York, D. Van Nostrand Co., 1935. FROM a thesis presented b y William H. drmistead, Jr., to the Graduate School of Vanderhilt University in partial ful6llmeut of the requirements for the degree of doctor of philosophy.
Determination of Ash in Coals Unusually High in Calcite and Pyrite 0. W. REES, Illinois State Geological Survey, Urbana, Ill., AND W. A. SELVIG, U. S. Bureau of Mines, Pittsburgh, Penna.
I
S D E T E R M I N I N G ash in coals containing unusually large amounts of calcite and pyrite, difficulty in obtaining satisfactory results by the standard A. S. T. RI. procedure (3) may be experienced] because of the varying amounts of sulfur that are retained as calcium sulfate in the ash. Variations in the heating procedure used in the ash determination influence the amount of sulfur retained. Lower ash and lower sulfur in the ash are obtained by slow rates of heating. This paper is a report of cooperative work done by the Analytical Laboratory of the Illinois State Geological Survey and the Pittsburgh Laboratory of the United States Bureau of Mines for the purpose of studying modified procedures for the determination of ash in such troublesome coals.
Experimental Tests For this work five sizes of coal prepared by screening from it large sample of 1 1 / 4 inch X 0 screenings from the KO. 2 bed, Woodford County, Ill., were used. The larger sizes were crushed t o pass a No. 4 sieve and after mixing and riffling all sizes, two 1-quart samples of each were cut out. One set of samples was sent to the U. S. Bureau of Mines Laboratory and one set was retained in the Illinois State Geological Survey Laboratory. The samples are designated as follows: Sample 1 2 3
Sine X 3 1 4 incli x 3/n inch a/'n inch X 10-mesli ll/r 314
Sample
t
Size 10 X 48-mesh - 48-nicsh
Each laboratory prepared its own samples for analysis b y the usual A. S.T. M. procedure ( I ) . Analyses in the two laboratories indicated that the two samples of each size were satisfactory duplicates, with the exception of sample 3. Because the two 1-quart portions differed in ash content by too large a n amount, the ash values reported by the Geological Survey laboratory were obtained on the 60-mesh coal prepared in t h e Pittsburgh laboratory. The coals were analyzed for total sulfur (Eschka method), and for forms of sulfur and carbon dioxide by methods of the U. S. Bureau of Mines ( 7 ) . Moisture at 105' C. mas determined by each laboratory on the samples according t o the A. S. T. 11.standard method ( 2 ) .
Bureau of Mines Determinations METHOD A. The dried samples were heated on the hearth of a hot muffle furnace for 8 minutes t o drive off volatile matter, then heated at 725' C. t o constant weight (within 0.001 gram). METHODB. The dried samples were placed in a cold furnace and heated t o 725" C. in 1.5 hours. The temperature was kept at 725" C. t o constant weight. METHODC (Parr's sulfated ash method, 5 , 6). The dried samples were burned by Method A and after cooling \yere moistened with a few drops of 1 to 1 sulfuric acid and dried on an air bath until the fumes were largely driven off. The samples were then heated at 725" C. t o constant \wight. This treatment produces a sulfated ash in 1% hich it is assumed that all calcium is present as the sulfate. To correct to a calcium oxide basis the percentage of sulfur trioxide, coal basis, determined in the sul-
,
210
Vol. 14, No. 3
INDUSTRIAL AND ENGINEERING CHEMISTRY
fated ash is subtracted from the sulfated ash or 1.82 times the mineral carbon dioxide, coal basis, is subtracted from the sulfated ash. In the latter method of correction it is assumed that the mineral carbon dioxide is a measure of the calcium carbonate present in the original mineral matter of the coal.
TABLEI. SULFURFORMS AND CARBON DIOXIDE Sample Sample Sample Sample Sample 1 3 2 4 5 Sulfate sulfur U. S. B. M. I. G. S. Pyritio sulfur U.S. B. M. I. G. S. Organic sulfur U. S. B. M. I. G. S. Total sulfur U.S. B. M.
%
%
%
%
%
0.06 0.01
0.08 0.02
0.07
0.11
0.12 0.07
METHOD D. The dried samples were placed in a cold furnace and heated to 400' C. in 0.5 hour. They were held at this temperature for a further 0.5 hour, then transferred to another furnace at 725' C. and heated to constant weight. One ash Sam le from each test was analyzed for total sulfur by the sodium carionate fusion method (7). The duplicate ash was tested for sulfide sulfur by the evolution method used for coke (8). Sulfate sulfur was determined in the hydrochloric acid solution from the sulfide tests. Ammonium hydroxide was added in slight excess and the precipitated iron together with any insoluble ash was removed by filtration. The filtrate was made slightly acid and the sulfur precipitated in the regular manner.
Geological Survey Determinations METHOD E. The dried samples were heated on the hearth of a hot muffle furnace for 10 minutes to drive off volatile matter, 0.67 1.03 1.30 2.28 3.14 moved just inside the furnace for 5 minutes, and then moved back 1.02 1.10 2.56 3.50 to the hot portion of the furnace where they were heated to constant weight a t 750" C. 0.72 0.69 0.58 0.55 0.52 METHODF. The dried samples were placed in a cold mufRe 0.53 0.49 0.40 0.19 furnace and heated to 7!0° C. in 1.75 hours. They were heated to constant weight at this temperature. 1.45 1.80 1.95 2.94 3.78 I. G. 9. 1.56 1.61 3.00 3.76 METHODG (Parr's sulfated ash method). The dried samples were burned by Method F and after cooling were treated with Carbon dioxide U.S. B. M. 0.29 0.53 1.59 4.24 3.63 1 to 1 sulfuric acid,"the excess acid was I. G. S. 0.47 0.64 4.10 3.64 fumed off on a hot plate, and the samples were heated to constant wei ht at 750' C. The ashes obtained by a f three methods were analyzed for sulfur trioxide by TABLE11. DETERMINATION OF ASH extraction with dilute hydrochloric acid, (Per cent of dry coal) precipitation and removal of RlOa with Sulfide in SOa- and SSulfide in SOs- and Sammonium hydroxide, with subsequent Ash SOainAsh Ash Free Ash Sample Ash SOainAsh Ash Free Ash precipitation of sulfate with barium chloride in acid solution. Sulfide sulfur deter--Data by Method A D a t a by Method E minations were made on the ashes ob0.46 8.82 9.40 0.29 0.04 9.09 9.28 1 tained by Methods E and F by the 0.40 0:OO 8.87 9.50 0.30 0.02 9.19 9.27 procedure mentioned above (8). 9.14 8.85 9.45 9.28 Av. The effect of using furnaces of different 13.72 0.22 0.02 13.57 0.62 13.80 14.37 2 sizes, in which the rate of chan e of 13.60 0.31 0.03 13.34 0:03 0.57 13.66 14.20 atmosphere varied, for duplicate teter13.66 13.46 13.73 Av. 14.29 minations was studied in the Geological 1.52 17.06 18.06 18.59 .. *. * . 3 Survey laboratory. One duplicate was 17.13 17.87 1.56 0161 18.70 ashed in the larger Hoskins F. D. 204 17.10 17.97 18.65 Av. furnace whose heating chamber is 7l/r 27.61 27.52 1.73 0.02 3.64 29.26 4 31.27 inches wide, 51/4 inches high, and 14 27.64 27.63 3.49 o:i2 1.28 0.02 28.92 31.15 inches long while the other was ashed in 27.63 29.09 27.58 31.21 Av. the smaller Hoskins F. D. 202 furnace 3.14 31.73 34.83 1.86 0.32 32.81 34.93 5 whose heating chamber is 41/1 inches 34.65 32.92 0:06 1.59 0.27 3.03 32.03 35.12 wide, 3 inches high, and l0.inches long. 34.74 31.88 32.87 Av. 35.03 Both furnaces were equipped with Data by Method F D a t a by Method B thermocouples placed loosely through 80s-Free SOrFree the back, so that air flow through the Ash Ash furnace would take place. 8.84 9.32 0.23 0.29 9.09 1 9.13 All tests in both laboratories were 0.24 8.83 9.33 9.09 9.09 0.26 made in electrically heated muffle fur8.84 9.33 9.09 9.11 Av. naces. 13.69 13.77 0.23 13.54 14.09 0.40 2 0.04
7 -
-
Av.
3 Av. 4 Av. 5 Av. 1 Av. 2 Av. 3
Av. 4
Av. 5
Av.
0.34
14.06 14.08 17.87 17.80 17.84 29.04 28.91 28.98 33.19 33.01 33.10
9.12 9.10 9.11 14.03 14.05 14.04 17.58 17.71 17.65 28.53 28.49 28.51 32.95 33.16 33.06
0.85 0.68 1.39 1.07 1.01 0.83 D a t a b y Method D 0.29 0.24
.
0.38 0.34 0.53 0.61 0.86 0.76
1.02 0.95
13.72 13.71 17.02 17.12 17.07 27.65 27.84 27.75 32.18 32.18 32.18
8.83 8.86 8.85 13.65 13.71 13.68 17.05 17.10 17.08 27.67 27.73 27.70 31.93 32.21 32.07
..
13.77 17.53 17.85 17.69 28.81 28.14 28.48 34.73 34.03 34.38
.. .. ..
0.70 0.68 1.45 1.24
..
13.54
.. ..
Results of Tests
Results of analyses of the coals for forms of sulfur and mineral carbon dioxide are given in Table I. Ash values as determined by the various methods, together with amounts of sulfur as sulfur trioxide retained in t h e ashes, are listed in Tables I1 and 111. Sulfide sulfur was found only in ashes obtained by Methods A and E. Table IV presents additional data- showing the effect of a slower rate of heating and ashing in furnaces of different sizes in which air circulation was different. Table V presents a comparison of average results obtained by different. methods. 28.11 27.46 27.79 33.28 32.79 33.04
Discussion The tolerances for permissible differences between ash de-terminations in the same laboratory and between different laboratories by the A. S. T. M. standard method (4) are 0.5
TABLE111. DETERMINATION OF ASH Sample
Sulfated Ash
1 Av. 2 Av.
3 Av. 4 Av. 5 Av.
-Results 9.81 9.82 9.82 15.15 15.18 15.17 20.43 20.49 20.46 35.62 35.68 35.65 39.38 39.59 39.49
(Per cent of dry coal) Sulfated Ash Less 1.82 50s in Sul- 508-Free X Mineral Sulfated fated Ash Ash con Ash by Method C -
1.05 1.00 1.54 1.50 3.43 3.49 8.09 8.15 7.42 7.50
8.76 8.82 8.79 13.61 13.68 13.65 17.00 17.00 17.00 27.53 27.53 27.53 31.96 32.09 32.03
9.28 9.29 9.29 14.22 14.25 14.24 17.56 17.62 17.59 27.88 27.94 27.91 32.78 32.99 32.89
-Results 10.15 10.23 10.19 14.86 14.99 14.93
SO: in Sul-
50s-Free Ash
fated Ash
Sulfated Ash Less 1.82 X Mineral
by Method G 0.76 9.39 0.84 9.39 9.39 1.21 13.65 1.25 13.74 13.70
coz
9.29 9.37 9.33 13.70 13.83 13.77
... ...
... ...
... ... ...
... ... ...
35.95 35.71 35.83 40.68 40.67 40.68
7.85 7.77
28.10 27.94 28.02 33.52 33.46 33.49
28.49 28.25 28.37 34.06 34.05 34.06
...
...
7.16 7.21
OF ASH VALUES TABLEIV. COMPARISON
Obtained b y varying time necessary for furnace t o reach 750' C., b y ashipg in different siced furnaces, and b y , applying [the modified Parr method where first burning off took place in different sized furnaces. D a t a by Illinois Geological Survey. Per Cent Ash, Starting with Cold Per Cent Ash Furnace Heating to Sulfated Modifikd Parr Method Per Cent of Ash 750' C. i'n 1.75 Hours Starting with Cold Large Small Large Small Per Cent Ash, ModiFurnace, Heating furnace furnace, furnace, furnace, fied Parr, Sulfated Ash t o 750' C. Hoskini Hoskins Less 1.82 X MinHoskins Hoskins Sample 1.5 hours 2.25 hours F. D . 204 F. D. 202 F. D. 204 F. D.202 era1 COa
1 2 3 4 5
9.14 14.08 17.89 29.07 33.28
21 1
ANALYTICAL EDITION
March 15, 1942
9.08 14.05 17.60 28.52 32.98
9.00 14.02 17.46 28.66 32.76
9.24 lf:f3 29.91 33.16
9.59 14.76 20.08 35.46 39.16
9.53 14.89 20.15 35.70 39.39
9.03 13.87 17.23 27.87 32.68
TABLEV. COMPARISON OF AVERAGE ASH VALUESOBTAINED BY METRODS A, B, D, E, AND F WITH METHODSC AND G (Per cent of dry coal) by U . S. Bureau of MinesMethod C, Method A, Method B, Method D Parr's -Difference Sample hot muffle cold muffle two muffle; method" Method A 1 9.28 9.11 9.11 9.29 -0.01 14.08 14.04 2 14.29 14.24 4-0.05 3 18.65 17.84 17.65 $1.06 17.59 4 31.21 28.98 28.51 27.91 +3.30 33.10 33.06 5 35.03 32.89 +2.14 -Data
from Method CMethod B Method D -0.18 -0.18 -0.16 -0.20 +0.25 +0.06 4-1.07 +0.60 $0.21 $0.17
-Data by Illinois Geological SurveyMethod E, Method F, Method G, -Difference from Method G-. hot muffle cold muffle Parr's method" Method E Method F 1 9.45 9.33 9.33 fO.12 0.00 2 13.73 13.77 13.77 -0.04 0.00 3 17.97 17.69 17.23 f0.74 $0.46 4 29.09 fO.11 28.48 28.37 +0.72 5 34.74 34.38 34.06 4-0.68 +0.32 Parr's sulfated ash less 1.82 X mineral COz.
and 0.5 per cent, respectively, on coals containing carbonates. For coals with more than 12 per cent ash containing carbonate and pyrite these are 0.5 and 1.0 per cent, respectively. For the most part results obtained by the various methods checked within these tolerances, both in the same laboratory and between the two laboratories (Tables I1 and 111), particularly the results corrected for retained sulfur. I n a few cases the results did not check within these tolerances but, with one exception, these results were for the last two samples (samples 4 and 5) which are high in mineral matter containing large amounts of mineral carbon dioxide and pyritic sulfur. The ash of these samples is considerably higher than would normally be encountered in commercial samples. The ash values obtained by Methods A and E, uncorrected for retained sulfur, are higher than those obtained by other methods with the exception of the Parr sulfated ashes,
Methods A and E correspond to a more rapid rate of heating and the ashes contain considerably greater amounts of retained sulfur than those obtained b y MethodsB, F , a n d D . Resultsobtained by Method D probably show the best agreement between duplicate determinations, with comparatively lower amounts of sulfur being retained in t h e ashes. Results obtained by the Parr sulfated ash method check reasonably well for the most part, but this procedure is rather long and requires mineral carbon dioxide values for use in correcting the sulfated ash obtained. I n Table IV are presented further data on the effect of different rates of heating, not corrected for sulfur retained in the ash. Lower results are obtained with the slower rate of heating. I n addition, information is presented on the use of different sized furnaces for ashing. The higher results obtained in the smaller F. D. 202 furnace indicate that sulfur trioxide a s formed was not removed as rapidly as in the larger furnace and was therefore fixed in the ash to a larger extent. The adequate removal of sulfur trioxide therefore becomes important. Use of the Parr sulfated ash method appears to smooth out these differences to some extent. Table V presents a comparison of average ash values obtained by the procedures tried. For those samples containing larger amounts of ash and mineral carbon dioxide the slower rates of heating give definitely better results when compared to those obtained by the Parr sulfated ash method. However, differences appear which are outside A. S. T. M. tolerances and in such cases the ash values should be corrected for retained sulfur or determined by the modified Parr method. It is not likely t h a t such samples would be encountered in commercial samples but they might be encountered in certain special studies.
Summary The preliminary hearth heating method (A and E) gave results within the A. s. T. M. tolerances for all duplicates obtained in the same laboratory. Checks between different laboratories within A. S. T. M. tolerances were obtained for coals containing up to about 3.6 per cent mineral carbon dioxide, but these ashes contained larger amounts of retained sulfur. The determination of ash by the cold furnace method (B and F) gave duplicate results within A. S. T. M. tolerances for all samples in the U. S. Bureau of Mines laboratory and for samples up to about 1.6 per cent mineral carbon dioxide content in the Illinois Geological Survey laboratory. Checks between average values from the two laboratories were within A. S. T. M. tolerances for all samples.
INDUSTRIAL AND ENGINEERING CHEMISTRY
212
Results obtained by the modified Parr method were all well within A. S. T. M. tolerances for duplicates in the samelaboratory. With the exception of results on one sample ( 5 ) , the checks between the two laboratories were within A. S. T. M. tolerances. The determination of ash by Method D gives duplicates checking within the 0.3 per cent tolerance for all samples. The adequate removal of sulfur trioxide from the furnace during ashing is important. As compared to results obtained by the modified Parr procedure, Methods A and E gave results within the A. S. T. M. 0.3 per cent tolerance for samples containing up to 0.6 per cent of carbon dioxide; Method B for coals up to 3.6 per cent of carbon dioxide; Method F for coals up to 4.2 per cent of carbon dioxide (with one exception); and Method D for coals containing up t o 3.6 per cent of carbon dioxide. Sulfur trioside-free ash values were similar for all methods. The slow heating method starting with a cold furnace appears to be satisfactory for determining ash in commercial samples of coal containing unusually large amounts of calcite and pyrite. Conclusions Methods A and E are not recommended for deterrnining ash in coals high in calcite and pyrite, hecause too much sulfur is retained in the ashes.
Vol. 14, No. 3
Methods B, D, and F give most consistent results, with Method D apparently giving the best results of the three. Methods C and G appear to give good results, especially for coals high in calcite and pyrite where other procedures studied are not so satisfactory. This procedure requires more work than other procedures. Adequate removal of sulfur trioxide from the furnace in which ashing takes place is necessary.
Literature Cited S.T. M.Standards, Part 111,Designation D 271-37, pp. 15-16 (1939). Ibid., pp. 20-1 (1939). Ibid., p. 21 (1939). Ibid., p. 41 (1939). Parr, S.W., Coal Mining Investigations, Ill. State Geol. Survey, Bull. 3, 35 (1916). Rees, 0. W., IND.ENG.CHEM.,ANAL.ED.,9, 307-9 (1937). Stanton, F. M., Fieldner, A. C., and Selvig, W. A., U. S.Bur. Mines, Tech. Paper 8, (1938). U. S.Steel Corp. Chemists, “Methods for Sampling and Analysis of Coal, Coke, and By-Products”, 3rd ed., p. 84, 1929.
(1) A. (2) (3) (4) (5)
(6) (7) (8)
PRESENTED before the Division of Gas a n d Fuel Chemistry a t the 102nd Meeting of the AMERICANCHQXICALSOCIETY,Atlantio City, N. J. Published by permission of the Chief, Illinois State Geological Survey, and the Director, Bureau of Mines, U. S. Department of the Interior.
Measurement of Color and Turbidity
in Solutions of White Granulated Sugars E. E. MORSE AND R. A. MCGINNIS, Spreckels Sugar Company, Woodland, Calif.
and
A practical method for the measurement of color and turbidity in solutions of granulated sugars is presented, a modification of the method of Keane and Brice. The two assumptions on which their method is based are shown to be not entirely justified. Color measurements with the new method are free from the influence of turbidity, and vice versa.
Tr
Tm X Trt
(3)
The notation is obvious. Keane and Brice assume that T,,is constant and equal to 1.00 for solutions of white sugars, stating that there is virtually no light absorption in the red part of the spectrum by the small amount of coloring matter present. From this assumption and Equation 3 they obtain Tr =
(4)
Trt
and set the turbidity index equal to the per cent absorbency of red light:
A
STRONG need for an adequate method for the measurement of color and turbidity in white granulated sugar solutions has been felt for some time. The best practical method has been that of Keane and Brice ( 2 ) , which as presented, however, has suffered from certain errors arising from the basic assumptions made.
They also set the ratio T,t/T,t equal to 1.00, although they state that it is only an approximation. Then from Equations 2 and 3, they obtain
,Mathematical Relationships The transmittancy of a turbidity-free sugar solution will be represented by T , and that of a colorless sugar solution by Tt. For a solution containing both color and turbidity, the transmittancy, T , is given by the fundamental expression
The color index is thus taken as the per cent absorbency of the blue-green light in a turbidity-free solution and by the assumptions above is expressed as I , = l O O ( 1 - Toe) = lOO(1 - Tg/Tr) (7)
T
=
T , X Tt
(1)
If the transmittancy measurements are made with light passed by different filters, say a blue-green and a red filter, then To Tgc X Tor (2)
It = l O O ( 1
- Trt) =
Ta/Tp = Tp/Tm X T,x/T,t
=
lOO(1
- T,)
T d l X 1 = Tu,
(5)
(6)
Sees (3) was not able to substantiate the assumption of Keane and Brice that both T,, and Tat/T,t equal 1.00. Nees suggested that experimentally determined factors be applied to correct the difficulty and proposed expressing color and turbidity in terms of percentage absorption of blue light. Sees’ method is not satisfactory, in that the use of an additive
