Characterization of Coal Macerals by Fluorescence Microscopy - ACS

Jul 23, 2009 - ... or discriminated both petrographically and statistically using various spectral parameters, specifically the wavelength of maximum ...
1 downloads 0 Views 1MB Size
3 Characterization of Coal Macerals by Fluorescence Microscopy JOHN C. CRELLING Department of Geology, Southern Illinois University at Carbondale, Carbondale, IL 62901 DAVID F. BENSLEY Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

Coal Research Section, The Pennsylvania State University, University Park, PA 16802 The use o f fluorescence microscopy to c h a r a c t e r i z e c o a l macerals is a s u c c e s s f u l recent innovation. Compared to conventional w h i t e - l i g h t a n a l y s i s , fluorescence microscopy r e v e a l s a greater number and v a r i e t y of macerals, as w e l l as, c h a r a c t e r i s t i c textures and s t r u c t u r e s . Although the s p e c t r a of f l u o r e s c e n t macerals are broad-peaked and, a t t h i s time, not s u i t a b l e f o r chemical s t r u c t u r e a n a l y s i s , they are c h a r a c t e r i s t i c of maceral types and rank. S p e c t r a l a n a l y s i s of the liptinite macerals in s i n g l e c o a l s of the Illinois Basin shows that the macerals can be grouped or d i s c r i m i n a t e d both p e t r o g r a p h i c a l l y and statistically using v a r i o u s s p e c t r a l parameters, specifically the wavelength of maximum i n t e n s i t y (λ max) and the red/green quotient (Q = i n t e n s i t y 650nm/500nm). In a num­ ber of cases the s p e c t r a l data r e v e a l the pres­ ence of more than one v a r i e t y of a given maceral type i n some samples. Maceral groupings on the b a s i s of i n c r e a s i n g λ max and Q c o n s i s t e n t l y show the same order: fluorinite, resinite, sporinite, cutinite. For example, i n the B r a z i l Block Seam (Indiana) the f o l l o w i n g maceral groups can be d i s ­ tinguished: f l u o r i n i t e (λ max = 520 nm, Q = 0.58), s p o r i n i t e type I (λ max =550 nm, Q = 0.85), s p o r i ­ n i t e type I I (λ max = 590 nm, Q = 1.00), c u t i n i t e (λ max = 610 nm, Q = 1.47). In a d d i t i o n , a l t e r e d (weathered) forms o f s p o r i n i t e (λ max = 690 nm, Q = 1.22) and c u t i n i t e (λ max = 650 nm, Q = 2.27) were a l s o observed. Studies on other c o a l samples of d i f f e r e n t ranks i n d i c a t e that the fluorescence p r o p e r t i e s are very s e n s i t i v e t o changes in rank. One of the major problems of c o a l science i s that very l i t t l e i s known about the b a s i c p r o p e r t i e s of the v a r i o u s macérais that make

0097-6156/84/0252-0033$06.00/0 © 1984 American Chemical Society

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

34

COAL

MACERALS

up c o a l . Two of the main reasons f o r t h i s l a c k of knowledge are that they are extremely d i f f i c u l t to separate from c o a l and that they are n o n - c r y s t a l l i n e organic compounds and, t h e r e f o r e , not good subjects to analyze with such standard methods as x-ray d i f f r a c t i o n or electron-microprobe a n a l y s i s . Some of the most succ e s s f u l c h a r a c t e r i z a t i o n of c o a l macérais to date has been done by pétrographie methods, i n which the i n d i v i d u a l macérais do not have to be separated. In the s t e e l i n d u s t r y , f o r example, pétrographie techniques have proven so s u c c e s s f u l i n allowing the p r e d i c t i o n of the coking p r o p e r t i e s of c o a l that most major s t e e l companies have now e s t a b l i s h e d pétrographie l a b o r a t o r i e s . Another pétrographie technique that has only r e c e n t l y been a p p l i e d to c o a l a n a l y s i s i s q u a n t i t a t i v e fluorescence microscopy. With t h i s technique, the v i s i b l e f l u o r e s c e n t l i g h t e x c i t e d from the macérais r e v e a l s shapes textures, and c o l o r s not v i s i b l e i n normal w h i t e - l i g h t viewing. The technique a l s o y i e l d s q u a n t i t a t i v e spectra that are charact e r i s t i c of both the i n d i v i d u a l maceral type and the rank of the coal. I t i s now a l s o w e l l e s t a b l i s h e d that a l l of the l i p t i n i t e macérais (coal components derived from the resinous and waxy plant m a t e r i a l ) and many of the v i t r i n i t e macérais (coal components derived from woody t i s s u e of p l a n t s ) w i l l f l u o r e s c e , and that some r e c e n t l y discovered l i p t i n i t e macérais can only be i d e n t i f i e d by t h e i r fluorescence p r o p e r t i e s . Some of the f i r s t measurements of the absolute i n t e n s i t y of fluorescence of c o a l macérais at s p e c i f i c wavelengths were made by Jacob (1,_2). R e l a t i v e i n t e n s i t y measurements of f l u o r e s c e n t spect r a of modern plant m a t e r i a l s , peats and coals have been reported by van G i j z e l (_3,_4,J>). Teichmuller (6,_Z,_8) described three prev i o u s l y u n i d e n t i f i e d members of the l i p t i n i t e group of macérais i n part by demonstrating t h e i r d i s t i n c t i v e s p e c t r a l p r o p e r t i e s . Ottenjann et a l (9.), Teichmuller (10). and Teichmuller and Durand (11), i l l u s t r a t e d the c o r r e l a t i o n of changes i n fluorescence spect r a of s p o r i n i t e with rank, and C r e l l i n g and others (12) and C r e l l i n g (13) have demonstrated the use of fluorescence spectra to d i s c r i m i n a t e macérais. In a d d i t i o n , Ottenjann et a l , F i s h e r (14), Teichmuller (10), and Teichmuller and Durand (11) have been able to r e l a t e the fluorescence spectra of v i t r i n i t e macérais to the t e c h n o l o g i c a l p r o p e r t i e s of c o a l . These studies have shown the p o t e n t i a l of using fluorescence measurements i n the study of l i p t i n i t e and v i t r i n i t e macérais. The o v e r a l l o b j e c t i v e of current fluorescence s t u d i e s at Southern I l l i n o i s U n i v e r s i t y at Carbondale i s to determine the kinds and r e l a t i v e amounts of f l u o r e s c e n t macérais i n various coals and to c l a s s i f y and d i s c r i m i n t e them on the b a s i s of t h e i r fluorescence s p e c t r a . A d d i t i o n a l o b j e c t i v e s are to d e f i n e the manner i n which the f l u o r e s c e n t macérais vary with c o a l rank, and to determine which of the macérais are of primary and secondary origin.

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

3.

CRELLING A N D BENSLEY

Fluorescence

Microscopy

35

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

Equipment and Methods The f l u o r e s c e n c e microscopy system used f o r t h i s study i n the SIUC Coal C h a r a c t e r i z a t i o n Laboratory i s a L e i t z MPV I I r e f l e c t a n c e microscope which i s f i t t e d with a 100 watt mercury arc lamp, a Pleom i l l u m i n a t o r and a L e i t z o i l immersion 40X o b j e c t i v e with a 1.3 numerical aperture. For s p e c t r a l measurements the l i g h t from the mercury a r c passes through a UG1 u l t r a - v i o l e t f i l t e r to a TK400 d i c h r o i c m i r r o r which r e f l e c t s l i g h t with wavelengths l e s s than 400 nm to the sample. The f l u o r e s c e n t l i g h t e x c i t e d from the sample i s passed through a 430 nm b a r r i e r f i l t e r to a motorized i n t e r f e r e n c e wedge i n f r o n t of the photometer. The i n t e r f e r e n c e wedge c o n t r o l s the wavelength of the f l u o r e s c e n t l i g h t h i t t i n g the photometer so that the i n t e n s i t y v a r i a t i o n s from 430 to 700 nm can be scanned and recorded i n about 20 seconds. The s p e c t r a l data are then fed from the microscope system i n t o a computer and d i g i ­ t i z e d , c o r r e c t e d , and analyzed. Each spectrum i s c o r r e c t e d f o r the e f f e c t s of background f l u o r e s c e n c e and f o r the e f f e c t s o f the microscope system, e s p e c i a l l y the s e n s i t i v i t y o f the photomultip l i e r tube, f o l l o w i n g c o r r e c t i o n procedures described by van G i j z e l (13). For comparison, the v a r i o u s s p e c t r a a r e normalized and reduced to a number of parameters such as: 1) the wavelength of maximum i n t e n s i t y peak (λ max); 2) the red/green quotient (Q) where Q = r e l a t i v e i n t e n s i t y a t 650 nm/relative i n t e n s i t y a t 500 nm; 3) the area l e s s than λ max; 4) the area greater than λ max; 5) area blue (430 to 500 nm); 6) area green (500 to 570 nm); 7) area yellow (570 to 630 nm); and 8) area r e d (630 to 700 nm). Results and D i s c u s s i o n In c o a l s of the I l l i n o i s Basin, standard w h i t e - l i g h t pétrographie methods g e n e r a l l y r e v e a l three types of l i p t i n i t e macérais; r e s i n i t e , s p o r i n i t e and c u t i n i t e . These macérais a r e i d e n t i f i e d on the b a s i s of t h e i r pétrographie p r o p e r t i e s such as r e f l e c t a n c e , s i z e , shape and t e x t u r e . When f l u o r e s c e n c e microscopy i s used, the fluorescence c o l o r s and i n t e n s i t i e s r e v e a l the presence of l a r g e r amounts of these macérais plus the presence of the new maceral, fluorinite. The combined r e s u l t s of maceral analyses i n both w h i t e - l i g h t and f l u o r e s c e n t l i g h t as w e l l as the r e f l e c t a n c e value for the H e r r i n (No. 6) B r a z i l Block and Hiawatha c o a l s a r e given i n Table 1. F l u o r i n i t e was f i r s t defined by Teichmuller (6) and i s chara c t e r i z e d by a very high f l u o r e s c e n c e i n t e n s i t y . I t commonly occurs i n most c o a l s of the I l l i n o i s Basin and i s shown i n F i g ures 1 and 2 along with photomicrographs of s p o r i n i t e and c u t i n i t e . When f l u o r e s c e n c e s p e c t r a l a n a l y s i s i s used on these samp l e s , the r e s u l t i n g s p e c t r a l data d i s t i n g u i s h these four types of l i p t i n i t e macérais plus a d d i t i o n a l v a r i e t i e s of r e s i n i t e , s p o r i n i t e and c u t i n i t e . For example, s p e c t r a l a n a l y s i s o f the v a r i o u s l i p t i n i t e macérais i n samples of H e r r i n (No. 6) c o a l seam with a

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

36

COAL MACERALS

Figure 1. W h i t e - l i g h t ( r e f l e c t e d ) photomicrographs o f l i p t i n i t e macérais. Diameter of frames i s 300 urn. l a (upper l e f t ) v e r t i c a l zones o f l i p t i n i t e (dark gray) a t l e f t and center. Bright spot i n center i s a p y r i t e c r y s t a l , l b (upper r i g h t ) some s p o r i n i t e lenses (dark gray) i n center of frame, l c (lower l e f t ) - l a r g e l i p t i n i t e mass a t center and some s c a t t e r e d spores (dark gray), Id (lower r i g h t ) - some l i p t i n i t e s t r i n g e r s running from top l e f t to bottom r i g h t .

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

3. CRELLING AND BENSLEY

Fluorescence

Microscopy

37

Figure 2. B l u e - l i g h t photomicrographs of l i p t i n i t e macérais. Diameter of frames i s 300 urn. 2a (upper l e f t ) same frame as l a , center zone of f l u o r i n i t e showing intense yellow f l u o r e s c e n c e , s p o r i n i t e with l e s s intense range f l u o r e s c e n c e i s seen a t l e f t , green at lower r i g h t i s the f l u o r e s c e n c e from the mounting medium, 2b (upper r i g h t ) same frame as l b - f l u o r e s c e n c e r e v e a l s spore (yellow ovoids) and a mass of granulated l i p t i n i t e i n center of frame, 2c (lower l e f t ) same frame as l c - f l u o r e s c e n c e r e v e a l s l a r g e mass a t center as a spore sac (sporangium), yellow ovoids are s p o r i n i t e and yellow s t r i n g e r s a r e c u t i n i t e . 2d (lower r i g h t ) same frame as Id - fluorescence r e v e a l s two d i f f e r e n t types of c u t i n i t e - a b r i g h t e r t h i c k e r v a r i e t y on the l e f t and a darker thinner v a r i e t y on the r i g h t .

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

38

COAL MACERALS

Table 1.

Results

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

Coal Seam Reflectance ( i n o i l a t 546 nm) Vitrinite Pseudovitrinite Fluorinite Resinite Sporinite Cutinite Amorphous Liptinite Semi-fusinite Fusinite Micrinite

of Combined White-Light and Fluorescent Pétrographie Analyses

H e r r i n (No, 6) S a l i n e Co,, IL 0.65%

B r a z i l Block Parke Co., IN 0.58%

Light

Hiawatha Carbon Co., UT 0.52%

65.1 19.8 0.3 0.1 3.0 0.4

56.3 8.7 0.2 0.7 14.1 2.0

73.7 7.8 0 6.9 0.5 0.8

1.8 5.7 2.1 1.7

4.2 4.9 3.4 5.5

1.0 4.2 1.3 3.8

r e f l e c t a n c e of 0.65% ( i n o i l at 546 nm) showed d i s t i n c t i v e spectra f o r the macérais f l u o r i n i t e , r e s i n i t e , s p o r i n i t e and c u t i n i t e . In t h i s case (Herrin No. 6 ) , the s p e c t r a were assigned to maceral groups on the b a s i s of the pétrographie i d e n t i f i c a t i o n of macérais from which the s p e c t r a were obtained. When the groups of s p e c t r a l data f o r each maceral type were subjected to d i s c r i m i n a n t f u n c t i o n a n a l y s i s of the eight d i f f e r e n t parameters f o r each spectrum, the maceral types were w e l l separated. From t h i s a n a l y s i s i t was e a s i l y seen that there are two d i f f e r e n t groups of r e s i n i t e macérais. Thus, the s t a t i s t i c a l a n a l y s i s of the s p e c t r a l parameters of the macérais revealed two v a e t i e s of the r e s i n i t e maceral group that could not be r e a d i l y d i s t i n g u i s h e d by normal pétrographie means. The average s p e c t r a of the v a r i o u s maceral types d i s t i n g u i s h e d by the d i s c r i m i n a t e f u n c t i o n a n a l y s i s are p l o t t e d i n Figures 3-6. A d d i t i o n a l study of these samples i n d i c a t e s that there are a l s o two v a r i e t i e s of f l u o r i n i t e present. The average s p e c t r a l data f o r a l l of the v a r i e t i e s of the f l u o r e s c e n t macérais i n these samples are given i n Table I I . In a study of the fluorescence p r o p e r t i e s of the B r a z i l Block seam (Parke Co., IN), a somewhat d i f f e r e n t approach was used. In t h i s case, about a hundred i n d i v i d u a l spectra were taken on a v a r i e t y of f l u o r e s c i n g l i p t i n i t e macérais. Although the macérais from which the spectra were tkane were not i d e n t i f i e d at the time of measurement, photomicrographs i n both normal w h i t e - l i g h t and f l u o r e s c e n t l i g h t were taken f o r documentation. The s p e c t r a l parameters f o r each spectrum were c a l c u l a t e d and these data were subjected to c l u s t e r a n a l y s i s to t e s t the degree to which the

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

450

500

550

Wavelength

600

650

700

(nm)

Figure 3. Average fluorescence s p e c t r a f o r two v a r i e t i e s o f f l u o r i n i t e i n the H e r r i n (No. 6) seam. The r e f l e c t a n c e of the seam i s 0.65%.

450

500

550

Wavelength

600

650

700

(nm)

Figure 4. Average fluorescence s p e c t r a f o r two v a r i e t i e s of r e s i n i t e i n the H e r r i n (No. 6) c o a l seam. The r e f l e c t a n c e of the seam i s 0.65%.

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

40

COAL MACERALS

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

Relative Intensity (%)

450

500

550

Wavelength

600

650

700

(nm)

Figure 5. Average f l u o r e s c e n c e spectrum f o r s p o r i n i t e i n the H e r r i n (No. 6) c o a l seam. The r e f l e c t a n c e of the seams i s 0.65%.

450

500

550

Wavelength

600

650

700

(nm)

Figure 6. Average fluorescence spectrum f o r c u t i n i t e i n the H e r r i n (No. 6) c o a l seam. The r e f l e c t a n c e of the seam i s 0.65%.

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

Fluorescence

3. CRELLING AND BENSLEY

Microscopy

41

Table I I . S p e c t r a l Parameter of the Average S p e c t r a l of Maceral V a r i e t i e s i n the H e r r i n No. 6 Coal Seam ( S a l i n e Co. - R = 0.65%)

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

Q

Parameter

Fluorinite I II

Resinite I II

Peak (nm)

500

524

553

Red/Green Quotient

0.47

0.57

0.94

Sporinite

Cutinite

604

657

682

1.67

1.63

2.99

groups could be separated on the b a s i s of t h e i r s p e c t r a l parameters. I t was found that seven groups could be d i s t i n g u i s h e d . The b a s i c pétrographie data f o r the B r a z i l Block c o a l seam are given i n Table I and the average s p e c t r a l parameters f o r each maceral group are given i n Table I I I . When the macérais from which the spectra were taken were i d e n t i f i e d from the photomicrogrphs, i t was found that each group corresponded to a separate maceral type or a v a r i e t y of a maceral type. There wae type of f l u o r i n i t e , one type of r e s i n i t e , three types of s p o r i n i t e and two types of c u t i n i t e . While t h i s correspondence o f maceral types and v a r i e t i e s to s t a t i s t i c a l groupings of s p e c t r a l data was not unexpected, i t i s f u r t h e r c o n f i r m a t i o n that the s p e c t r a l parameters of macérais are unique to maceral type and v a r i e t y . Table I I I .

Parameter

S p e c t r a l Parameters of Average Spectra of the B r a z i l Block Coal Seam

Fluorinite

Peak (nm) 480 Red/Green 0.32 Quotient Area Blue (%) 37 Area Green (%) 38 Area Yellow 15 (%) Area Red (%) 10 Area L e f t 21 of Peak (%) Area Right 79 of Peak (%)

Sporinite II III

Cutinite I II

Resinite

I

520 0.58

550 0.85

590 1.00

690 1.22

610 1.47

650 2.27

19 43 23

16 36 25

14 34 28

13 31 26

12 32 28

7 29 29

15 33

23 40

24 53

30 93

28 59

35 60

67

60

47

7

41

40

An i n t e r e s t i n g r e s u l t of t h i s a n a l y s i s i s that one of the

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

42

COAL

MACERALS

s p o r i n i t e v a r i e t i e s (II) and one of the c u t i n i t e v a r i e t i e s (II) d i s t i n g u i s h e d by s t a t i s t i c a l means showed pétrographie evidence of a l t e r a t i o n (weathering). Because the c o a l sample i t s e l f was c o l l e c t e d from a f r e s h exposure at an a c t i v e mine, i t appears that the weathered maceral v a r i e t i e s were weathered before they were incorporated i n t o the peat that was l a t e r c o a l i f i e d . The r e s u l t s of these two s t u d i e s show that fluorescence s p e c t r a l a n a l y s i s can d i s t i n g u i s h , on a q u a n t i t a t i v e b a s i s , the v a r i o u s types of l i p t i n i t e macérais and, indeed, even v a r i e t i e s of each type. That the v a r i o u s spectra are unique to the i n d i v i d u a l macérais i s f u r t h e r i n d i c a t e d by the recurrent order of the spect r a l parameters, e s p e c i a l l y the wavelength of maximum i n t e n s i t y (λ max) and the red/green quotient i n any given c o a l . For example as shown i n Figures 3-6 f o r the H e r r i n (No. 6) seam and as seen i n Table I I I f o r the B r a z i l Block seam, the order of the maceral types on the b a s i s of i n c r e a s i n g λ max and Q i s f l u o r i n i t e , r e s i ­ n i t e , s p o r i n i t e and c u t i n i t e . I t should be noted, however, that as the rank of c o a l i n c r e a s e s , a l l of the s p e c t r a l peaks s h i f t toward longer wavelengths and d i m i n i s h i n i n t e n s i t y and are, thus, even­ t u a l l y d i f f i c u l t or impossible to d i s t i n g u i s h from each other. Weathering of the macérais has a s i m i l a r e f f e c t . The p r e l i m i n a r y r e s u l t s of s t u d i e s now underway suggest that the s p e c t r a l peak (λ max) of some macérais, i s more s e n s i t i v e to v a r i a t i o n i n c o a l rank than p r e v i o u s l y b e l i e v e d . In the high v o l a t i l e bituminous c o a l s s t u d i e d , an increase of 3 V-types (0.45 0.75% r e f l e c t a n c e ) r e s u l t e d i n about a 50 nm increase of λ max. Even when macérais have been a l t e r e d by l a r g e increases i n rank, or weathering, or other processes, fluorescence microscopy can s t i l l be q u i t e u s e f u l i n c h a r a c t e r i z i n g c o a l macérais. For example, some c o a l seams i n the western U.S. have an abundance of r e s i n i t e which i n some cases i s being extracted and commercially e x p l o i t e d as a chemical raw m a t e r i a l . The r e s i n i t e i n these seams most o f t e n occurs as a secondary m a t e r i a l , f i l l i n g f i s s u r e s and voids i n the c o a l . Numerous flow t e x t u r e s , i n c l u s i o n s of c o a l i n r e s i n i t e v e i n l e t s , and i n t r u s i v e r e l a t i o n s h i p s throughout c o a l seams i n d i c a t e that the r e s i n i t e was m o b i l i z e d at some point i n i t s h i s t o r y . These secondary r e s i n i t e s are o f t e n d i f f i c u l t to detect i n normal w h i t e - l i g h t viewing; however, they a l l tend to f l u o r e s c e s t r o n g l y d i s p l a y i n g a v a r i e t y of c o l o r s and are theref o r e , q u i t e amenable to fluorescence a n a l y s i s . When samples of the Hiawatha seam from Utah were examined by C r e l l i n g et a l (12) four types of secondary r e s i n i t e s , each w i t h a d i f f e r e n t f l u o r e s cence c o l o r - grren, yellow, orange, red-brown - were seen. Each r e s i n i t e type has a spectrum that i s d i s t i n c t i v e and the v a r i o u s types can be s t a t i s t i c a l l y separated on the b a s i s of t h e i r spect r a l parameters. The average spectra of the four r e s i n i t e types are shown i n Figure 7 and the b a s i c pétrographie a n a l y s i s of the sample from the Hiawatha seam i s given i n Table I. I t should be noted t h a t , at t h i s time, the only way to d i s t i n g u i s h the v a r i o u s types of secondary r e s i n i t e i s with fluorescence microscopy.

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

3.

Fluorescence

CRELLING A N D BENSLEY

o I

i-H 450

Microscopy

43

1

1

1

1

500

550

600

650

Wavelength

\ 700

(nm)

Figure 7. Average fluorescence s p e c t r a f o r four v a r i e t i e s of r e s i n i t e from the Hiawatha Seam, Utah. V a r i e t i e s 1, 2, and 3 have a d e f i n i t e shape and a b r i t t l e f r a c t u r e while v a r i e t y 4 occurs only as a v o i d f i l l i n g . The r e f l e c t a n c e of the seam i s 0.65%.

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

44

COAL MACERALS

Work i s now underway to separate these v a r i o u s r e s i n i t e types using d e n s i t y gradient techniques and to chemically c h a r a c t e r i z e the separated r e s i n i t e f r a c t i o n s .

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

Summary Although the c h a r a c t e r i z a t i o n of c o a l macérais on the b a s i s of t h e i r f l u o r e s c e n c e s p e c t r a i s a recent innovation, i t has already proven to be an e x c e l l e n t f i n g e r p r i n t i n g t o o l f o r the v a r i o u s macérais. In some cases, i t i s even more s e n s i t i v e than normal pétrographie a n a l y s i s . The i n i t i a l r e s u l t s of fluorescence spect r a l s t u d i e s show that the v a r i o u s f l u o r e s c e n t macérais i n s i n g l e c o a l s can be s t a t i s t i c a l l y d i s c r i m i n a t e d on the b a s i s of t h e i r s p e c t r a l parameters and that even v a r i e t i e s of a s i n g l e maceral type can be d i s t i n g u i s h e d . Although the spectra obtained at t h i s time are r a t h e r broad and not s u i t a b l e f o r chemical s t r u c t u r e a n a l y s i s , the p o t e n t i a l f o r s t r u c t u r a l a n a l y s i s e x i s t s and may be r e a l i z e d with improvements i n instrumentation. Acknowledgments Much of t h i s work has been supported by the Gas Research I n s t i t u t e under Grant No. 5082-260-0618 and a l s o by the Coal Research Center at SIUC. This support i s g r a t e f u l l y acknowledged. Literature Cited 1.

2.

3.

4.

5.

6.

7.

Jacob, Η., Neue Erkenntnisse auf dem Gebiet der LumineszensMikroskopie f o s s i l e r Brennstoffe. - F o r t s c h r . Geol. Rheinld. u. Westf. 1964, 12, 569-588. Jacob, Η., Mikroskop-Photometrie der organischen S t o f f e von Boden I. Organopetrographische Nomenklatur und mikroskop­ -photometrische Methodik. -Die Bodenkultur, 1972, 23, 217226. van G i j z e l , P., Autofluorescence of fossil p o l l e n and spores with s p e c i a l reference to age determination and coalification. Leidse Geol. Meded., 1967, 50, 263-317. van G i j z e l , P., Review of the UV-fluorescence microphotometry of f r e s h and fossil exines and exosporia. "Sporopollenin"; Brooks, J . , Grant, P. R., Muir, M. D., van G i j z e l , P., and Shaw, G., Eds.; Academic Press: New York, 1971, pp. 659-685. van G i j z e l , P., Polychromatic UV-fluorescence microphotometry of f r e s h and fossil p l a n t substances with s p e c i a l reference to the l o c a t i o n and i d e n t i f i c a t i o n of dispersed organic m a t e r i a l i n rocks, i n "Petrographic Organique et P o t e n t i a l Pétrolier"; Alpern, B., Ed.; CNRS: P a r i s , 1975, pp. 67-91. Teichmuller, M., Uber neue Macerale der L i p t i n i t - G r u p p e und d i e Entstehung von M i c r i n i t . F o r t s c h r . Geol. Rheinld. u. Westf., 1974a, 24, 37-64. Teichmuller, M., Entstehung and Veranderung bituminoser Sub-

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

3.

8.

9.

Downloaded by UNIV OF SYDNEY on September 29, 2015 | http://pubs.acs.org Publication Date: May 8, 1984 | doi: 10.1021/bk-1984-0252.ch003

10.

11.

12.

13.

14.

15.

CRELLING AND BENSLEY

Fluorescence

Microscopy

45

stanzen i n Kohlen i n Beziehung zur Entstehung and Umwandlung des E r d o l s . F o r t s c h r . , Geol. Rheinld. u. Westf., 1974b, 24, 65-112. Teichmuller, Μ., Generation of p e t r o l e u m - l i k e substances i n c o a l seams as seen under the microscope. Advances i n Organic Geochemistry-1973. Ottenjann, Κ., Teichmuller, Μ., and Wolf, Μ., S p e c t r a l f l u o r e s c e n c e measurements i n s p o r i n i t e s i n r e f l e c t e d l i g h t and t h e i r a p p l i c a b i l i t y f o r coalification s t u d i e s , i n "Petro­ graphic Organique et P o t e n t i e l Petolier"; A l p e r n , Β., Ed.; CNRS: P a r i s , 1974c, pp. 379-407. T e i c h m u l l e r , M a r l i e s , Fluoreszenzmikroskopische Anderungen von L i p t i n i t e n und Vitriniten mit zunehmendem Inkohlungsgrad und i h r e Beziehungen zu Bitumenbildung und Verkokungsverhalten. Geologischer Landesamt Nordrhein-Westfalen, K r e f e l d , 1982, pp. 1-119. Teichmuller, M., and B. Durand, Fluorescence m i c r o s c o p i c a l rank s t u d i e s on liptinites and vitrinites i n peat and c o a l s and comparison with r e s u l t s of the r o c k - e v a l p y r o l y s i s . Int. Jour. of Coal Geology, 1983, 2, pp. 197-230. C r e l l i n g , John C., Dutcher, R u s s e l l R., and Lange, R o l f V., Petrographic and f l u o r e s c e n c e p r o p e r t i e s of r e s i n i t e macerals from western U.S. c o a l s . Proceedings of the Fifth Symposium on the Geology of Rocky Mountain Coal., 1982, pp. 187-191. C r e l l i n g , John C., Current uses of f l u o r e s c e n c e microscopy i n c o a l p e t r o l o g y . J o u r n a l of Microscopy, 1983, 132, p t . 3, 132-147. Ottenjann, Κ., Wolf, M. and W o l f - F i s c h e r , Ε., Beziehugen zwurischen der Fluoreszenz von Vitriniten und den t e c h n o l o g i schen Eigenschaften von Kohlen. Proc. I n t e r n a t i o n a l Conf. of Coal Science, 1981, pp. 86-89. van Gijzel, P., Manual of the techniques and some g e o l o g i c a l a p p l i c a t i o n s of f l u o r e s c e n t microscopy. Workshop sponsored by Am. Assoc. of S t r a t . P a l y n o l o g i s t , Core L a b o r a t o r i e s , Inc., D a l l a s .

RECEIVED January 1, 1984

In Chemistry and Characterization of Coal Macerals; Winans, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1984.