Estimating Oil Yield of Lean Oil Shale K. E. STANFIELD Petroleum and Oil Shale Experiment Station, U. S. Bureau of Mines, Lararnie, W j ,
SIMPLE,
rapid method is described for estimating the oil yield
A of lean oil shale by heating a 3-gritm sample for 5 minutes at 600' C. The yield of oil is then estimated by comparison with results obtained by treating oil shale samples of known oil yields to '/,a in the Same manner. The test requires approximately '/x~ the time required for assays by the modified Fischer-retort method and provides a means of detecting lean oil shales which yield insufficient oil to warrant the regular assays. Since the Bureau of Mines synthetic liquid fuels program mm8 initiated in 1944, approximately 17,000 oil shale samples have been assayed by the modified Fischer-retort method ( 1 ) t o determine the richness and extent of oil shale deposits in the United States. Initially, most of the samples were derived from rich oil shale deposits. Recently, many of the samples were drill euttinga from oil and gas wells which were submitted to identify and determine the extent of oil shales in the Green River formation: the majority of these samples yielded very little oil. To evaluate these oil shales, yet avoid assays by the more timeoonsuming modified Fischer-retort method, the rapid oil-yield test was developed. This test is suitable for estimating oil yields up to 3 gallons of oil per ton and ia similar, in principle, to B test proposed by Winchester (2) for evaluating oil shale specimens in the field.
Estimated Yield of Oil, Appearance of Upper k'art oi l e s t l u b e Gallons/Ton after Retorting Period None Trace (0.1 to 0.3) 0.3 to 1.0 Carbon ring and droplets or film of oil I to 3 Carbon ring and considerable oil which More than 3 may distill partly from the test tube DlSCUSSlON
The test is designed to estimate the oil yields of lean oil shales by comparison with results obtained on comparable samples of known oil yield. By the test, absence of oil is readily determined, and ail yields of 3 gallons per ton, or lesa, o m he estimated within the limits tabulated above. Oil yields exceeding 3 gallons per ton can 8180 be estimated, hut the aoouracy decreases with increase in oil yield. Accordingly samples yielding more than 3 gzllons of oil per ton should he assayed.
EQUIPMENT
Electric mume furnace (Figure 1)which consists of a refractorylined chamber 14 inches long by 51/2 inches wide by 4'/, inehee high with a Transite (Johns-Msnville, New York, N. Y.) cover contkining twelve 6/8-inch diameter holes spaced about 2 inches apart. The chamber, exclusive of cover, is insulated from an outside Transite case by Vermiculite high temperature cement (International Vermiculite Co., Girmd, Ill.). The furnace is mnintained manually a t the desired temperature by the use of a 1480watt heating unit (in hottam of furnace chamber), 15 amp., Variae transformer (General Radio Co., 279 Masssehusetts Ave., Cambridge, Mass.) and iron-oonstantan or Chromel-Alumel thermocouple (Hodins Manufacturing Co., Litwton ;U Kinnison Ave., Detroit Mich.) with indicating pyrometer. Sample mea&ng cup with a capacity of approximately 3 grams of ail shale. Borosilicate elass test tubes with lin. outside diameter ~.q/,&mh .. by 5 inches long. Transite tray, inch thick, with twelve holes corresponding to those in the furnace cover. Tray is fitted with legs approximatelv 2 L / r inches hieh to susoend the test tubes in the furnace to a d d h i f 2 inches. "
Figure 1.
Retorting Assembly
The shale oils generally darken and tend to carbonize during the latter part of the retorting period. However, colorless shale oils may he obtained occasionally. For this reason, observation of the shale distihte during retorting should not be omitted. In some instances, particularly on samples yielding approximately 3 gallons or mare of oil per ton, sufficient oil may be farmed t o drain, on cooling, onto the shale residues in the bottoms of the test tubes. Aside from variations in estimates by different analysts, factors affecting the estimated oil yields are (1) Temperature and period of retorting
(2) Weight of shale sample vent deposition of dust on the si& walls of the test tub'es.
(3) Presence of dust on the test tube walls
'
PROCEDURE
By means of the sampling cup and glass sleeve, approximrttely 3 grama of the crushed shales (minus Rmesh per inch, or finer) are placed in the bottoms of the test tubes in the Transite tray. The tray is placed on the furnace, and the test tubes are suspended to a denth of 2 inches into the furnace. which is maintained a t 600'
At retorting temperatures of 600" =t50" C., evolution of oil starts after approximately 3 minutes and, except for very rich oil shales, the evolution of ail is complete within 5 minutes. By the sampling cup, the weights of the minus 8-mesh per inoh samples range from 2.7 to 3.3 grams, depending upon their finene58 and specific gravity: these variations do not affect the estimated oil yields within the limits tabulated above. Deposition of dust upon the side wdllls of the test tubes during insertion of the shale sample should he avoided as the depoait of oil, or carbon ring by the test, tends to be irregular and more difficult to estimate. The time saved by utilizing the test to evaluate lean oil shales, which need not be assayed by the modified Fischer-retort method varies considerably, depending upon the type and number of the shale samples. Based upon retorting time alone, which neglects several other factors effecting a saving in time, the oil yield deter1552
V O L U M E 25, N O . 10, O C T O B E R 1 9 5 3 minations require k/12 to the time required for assays by the modified Fischer-retort method. &W deterioration of the f u r ~ due e to periodic heating and cooling can be minimized by maintaining the furnace at a moderate temperature, a8 100" to 150" C., between tests. Breakapt' of borosilicate glasb test tubes is negligible. In 1000 tests no Lest tubes were broken or cracked duriug - the heating- operation; . however, 3 tubes were broken during the cleaning operation. The test tubes may be cleaned by soaking in benzene, folloned by washing with soap and water and a tube brush or st.eel wool, if necessary.
1553 ACKNOWLEDGMENT
The ashistance of W. S. McAuley, J. C. Curran, and J. J. Cummins, lvho c,onducted most of the experimental lvork, is gratefully acknowledged. LITERATURE CITED
(1) Stanfield. K. E., and Frost, I. C., U. S. Bur. Mines, Rept. Inzest. 4477 (1949).
(2) Winchester, Dean C., U. S. Bur. Mines, B d . 729, 13 (1923). RECEIVED for review .\lay 29, 1953. Accepted July 7 , 1953.
Quantitative Determination of 1,2=Glycolsin Mixtures EDWARD A. ADELBERG Department of Bacteriology, University of California, Berkeley, Calif. URISG
the course of investigations on the biosynthesis of
D isoleucine and valine, it became necessary to determine quantitatively the a,p-dihydroxy acid precursors of these compounds Lvhen present simultaneously in filtrates of Sez~rospora cultures ( 4 ) . The method employed consists of chromatographirig t,he filtrates on paper, eluting the identified dihydrosy compound spots, and determining the eluted compounds colorimetrica1l.y after their conversion to carbonyl-containing fragments by periodate oxidation. I n the present work three compounds were used: o,8-dihSrdroxy--p-eth~lbut?-ric acid, a,p-dihydroxy-pmethylbutyric acid, and tartaric acid. When carried out with the precautions described helou, the method affords 1 0 0 ~ oreof these compounds \vith a maximum error of &lo%. The mcthod should be applicable to any compound ivhich can be cleaved by periodate to carbonyl-containing fragments, including otlicr glycols and such conipounds as serine and threonine.
on thc slicctt, so that each spot could be compared with a blank immetiiatcly adjacent to it. Elutioii Mas accomplished by cutting out each rectangle, wetting one edge ~11thwater, and attaching t o a paper wick down which r a t e r was flowing by capillarity from a chromatography trough. The rectangles were modified to provide a drip tip a t the bottom; Klett tubes were clipped in place below to catch the drops from each rectangle. It was extremely important to wash the wick immediately before use by allowing water t o descend through it, since the watei front coming off the wick repeatedly brought down a concentrated band of carbonyl material, yielding high and variable blanks. The wick must not dry out betaeen washing and attaching the paper to be eluted. Elution n as allowed to proceed until all bromophenol blue color has been washed off the papers; this required 4 to 5 drops.
600 I
EXPERIMEfiTAL
Solutions. Sodium metaperiodate, 40 micromoles per ml. (8.6 nig. per ml.). I'otassiuni iodide, 200 micromoles per nil. in 6 S hydrochloric acicl ( 3 3 nig. per ml.). 1Iake up immediately before use. Sodium thiosulfate, 20 micromoles/ml. ( 5 m y . of sodium thiosulfate pentahvdrate per nil.). 2,~-I)initrophenylhydra~iric, saturated Poiution in 2 -Yhydrochloric acid. 3 S sodium hydroxide. Chromatography. T-ntreated Whatman S o . 1 sheets were used in all cases. For the isoleucine and valine urecursors. the solvent system was a 70% ether-30% benzene mixture, made 3 M with foiniic acid and saturated with water ( 1 ) . In this system the isoleucine precursor has an R, of 0.7 and the valine precursor an ,?i of 0.4. Tartaric acid was found to move satisfactorily in water-saturated n-butanol made 3 with formic acid ( R j = 0.27). It was found essential to treat the solvents with ferrous sulfate solution; otherwise, losses of up to 30% of the glycol oceuried because of peroxide artion during chromatography. Since the compounds used in these experiments were all organic acids, they were detected by spraying lightly with bromophenol blue in ethanol ( S ) , the dye having been found not to interfere with subsequent steps in the procedure. For nonacid g1j cols a method of detection has been described by Buchanan et ai. ( 2 ) . If the procedure described below were to apply in such cases, the spots to be eluted would have to be located in unsprayed areas by comparison with sprayed guide strips. Elution. A modified rectangle was penciled around each spot with the aid of a stencil; use of the stencil ensured the elution of strictly comparable areas of paper in all cases, including areas used as blanks. The size of the rectangle was so chosen that ample margins were left around all spots. Blanks were outlined with the same stencil, at the same R, as the compound being determined. One blank was provided between each two spots
I
"
r\
I
I
500 W
$400 w (L
I-
300
c w
< 200 02
04
06
08
u , M GLYCOL
IO
12
"8"
Figure 1. Glycol Determinations 0 Sample solutions treated with periodate and de-
termined direatly 0 Samples chromatographed, eluted, and detsrmined as described in text A . d-Tartaric acid B. a,p-Dihydroxy+-methylbutyric acid Values plotted are net after subtracting blanks, in caee of chromatographed material
Oxidation. T o each Klett tube, containing the drops of eluted material, 1ml. of water was added. Each tube then received 0.1 ml. of metaperiodate solution a t 30-second intervals, followed at exactly 5 minutes in each case by 0.1 ml. of potassium iodide solution. Preliminary experiments showed that maximum color resulted with an oxidation period of 5 minutes a t room temperature. The addition of the acidified potassium iodide solution stopped
