Coal Desulfurization

11 Applicability of the Meyers Process for Desulfurization of U.S. Coal (A Survey of 35 Coals) J. W. HAMERSMA, M. L. KRAFT, and R. A. MEYERS

Downloaded by HARVARD UNIV on June 28, 2014 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0064.ch011

TRW

Systems and Energy, Redondo Beach, CA 90278

The Meyers process (1,2) is a new chemical leaching process which allows many coal-fired power plants and industrial sources to meet federal and state sulfur oxide emission standards without the use of flue gas cleaning. This process uses a regenerable aqueous ferric sulfate leaching unit to chemically convert and remove the pyritic sulfur content of the coal as elemental sulfur and iron sulfate. Although only pyritic sulfur is removed (organic sulfur remains), the Meyers process has wide applicability for converting U.S. coal reserves to a sulfur level consistent with present and proposed governmental sulfur oxide emission standards. Thirty-five mines from the major coal basins were investigated in this study. Because of the relatively high pyritic sulfur and low organic sulfur contents and because of high production of Appalachian coals (70% of current U.S. output), the Meyers process appears to have major impact in this area. In the Meyers process, aqueous ferric sulfate is used at 90°130°C t o oxidize selectively the pyritic sulfur c o n t e n t o f coal t o y i e l d i r o n s u l f a t e and f r e e e l e m e n t a l s u l f u r a s shown i n E q u a t i o n 1. The i r o n s u l f a t e d i s s o l v e s i n s o l u t i o n w h i l e t h e f r e e s u l f u r i s removed f r o m t h e c o a l m a t r i x e i t h e r b y v a p o r i z a t i o n o r s o l v e n t extraction. The l e a c h i n g ( o x i d i z i n g ) a g e n t i s t h e n r e g e n e r a t e d a t a s i m i l a r t e m p e r a t u r e u s i n g o x y g e n o r a i r and i s r e c y c l e d w h i l e p r o d u c t i r o n s u l f a t e s a r e removed b y l i m i n g a n d / o r c r y s t a l l i z a t i o n . 4.6 F e ( S 0 ) 2

4

3

+ 4.8 H 0 + F e S 2

2

10.2 FeSO^ + 4.8 H S 0 2

4

+ 0.8 S ( 1 )

The d e t a i l e d c h e m i s t r y , l e a c h i n g c o n d i t i o n s , r e a c t i o n k i n e t i c s , p r o c e s s e n g i n e e r i n g , and c o s t e s t i m a t e s h a v e b e e n p u b l i s h e d (3,4,5,6,7), and a r e a c t o r t e s t i n g u n i t has been b u i l t . T h i s c h a p t e r p r e s e n t s e x p e r i m e n t a l r e s u l t s and d i s c u s s i o n for: p y r i t i c s u l f u r removal from c o a l , p y r i t i c s u l f u r p a r t i t i o n by f l o a t - s i n k s e p a r a t i o n f r o m t h e same c o a l s , t h e e f f e c t o f t h e Meyers p r o c e s s on t h e t r a c e element c o n t e n t o f t h e t r e a t e d c o a l s , and a p p l i c a b i l i t y o f t h e M e y e r s p r o c e s s f o r m e e t i n g a i r p o l l u t i o n

143

In Coal Desulfurization; Wheelock, T.; ACS Symposium Series; American Chemical Society: Washington, DC, 1977.

144

C O A L DESULFURIZATION

c o n t r o l standards. T h i s w o r k was p e r f o r m e d u n d e r c o n t r a c t t o E n v i r o n m e n t a l P r o t e c t i o n Agency ( 8 , 9 ) .


Sulfur

the

Reduction

A summary o f t h e s u l f u r a n a l y s e s o f t h e r u n - o f - m i n e c o a l u t i l i z e d i n t h i s s t u d y i s shown i n F i g u r e 1. The o r g a n i c and p y r i t i c s u l f u r c o n t e n t s a r e p l o t t e d a l o n g t h e x-and y - a x i s r e s p e c t i v e l y w h i l e t h e sum o f t h e s e v a l u e s f o r a g i v e n c o a l c a n be reaù f r o m t h e diagonal lines. The a v e r a g e c o a l f o r t h i s s u r v e y c o n t a i n e d 2.02% p y r i t i c s u l f u r and 3.05% t o t a l s u l f u r . This corresponds to the U.S. B u r e a u o f M i n e s a v e r a g e f o r 325 raw c o a l s ( 1 0 ) , i n d i c a t i n g that the survey c o a l s r e p r e s e n t r e a s o n a b l y the s u l f u r d i s t r i b u t i o n i n U.S. coal. The r e s u l t s t o d a t e f o r c h e m i c a l r e m o v a l o f p y r i t i c s u l f u r (100-150 μ t o p - s i z e c o a l ) and t h e o p t i m a l r e s u l t s f o r c o n v e n t i o n a l c o a l w a s h i n g ( b a s e d on t h e 1.4 mm, 1.90 f l o a t f r a c t i o n o f a f l o a t s i n k a n a l y s i s ) a r e shown i n T a b l e I , i n t e r m s o f t o t a l s u l f u r c h a n g e s , and i n g r a p h i c a l f o r m i n F i g u r e 2. The t a b l e d e s c r i b e s t h e r e s u l t s o b t a i n e d on c o a l s w h i c h c o n t a i n e d s u f f i c i e n t p y r i t i c s u l f u r f o r a c c u r a t e s u l f u r r e m o v a l d e t e r m i n a t i o n ( i . e . , >0.25% w/w). Three of the mines sampled were below t h i s l i m i t and, t h e r e f o r e , do n o t a p p e a r i n t h e t a b l e . A c t u a l t o t a l s u l f u r v a l u e s b e f o r e and a f t e r c h e m i c a l r e m o v a l a r e shown i n columnsΟ and 4. These may be compared w i t h c o l u m n 5, w h i c h shows s u l f u r v a l u e s w h i c h c a n be o b t a i n e d w i t h f u l l p r o c e s s o p t i m i z a t i o n . T h i s l a t t e r v a l u e was c a l c u l a t e d by a d d i n g t h e a c t u a l r e s i d u a l p y r i t i c s u l f u r and s u l f a t e c o n t e n t s of the c o a l to the i n i t i a l o r g a n i c s u l f u r v a l u e a f t e r c o r r e c t i o n f o r any c o n c e n t r a t i o n e f f e c t s r e s u l t i n g f r o m a s h r e moval. I n the survey program, complete removal of r e s i d u a l e l e m e n t a l s u l f u r and s u l f a t e was n o t a l w a y s o b t a i n e d s i n c e c o n d i t i o n s were s t a n d a r d i z e d but not o p t i m i z e d f o r each i n d i v i d u a l c o a l . T h u s , f o r e x a m p l e , a l t h o u g h 96% p y r i t e c o n v e r s i o n was o b t a i n e d f o r t h e B i r d No. 3 c o a l , t h e t o t a l s u l f u r was r e d u c e d t o 0.80%, n o t t h e t h e o r e t i c a l 0.45% c a u s e d by t h e s e e f f e c t s . These p r o c e s s i n g p r o b l e m s h a v e now b e e n r e s o l v e d as p a r t o f o t h e r p r o j e c t s ( 3 , 9 ) , and t h e v a l u e s shown i n c o l u m n 5 can be c o n s i d e r e d t o r e p r e s e n t the t r u e p o t e n t i a l of the p r o c e s s . Because of the widespread a p p l i c a t i o n of p h y s i c a l c l e a n i n g t e c h n i q u e s f o r removal of nonc o m b u s t i b l e r o c k ( w h i c h i n c l u d e s v a r y i n g amounts o f p y r i t e a l o n g w i t h some c a r b o n ) f r o m c o a l , f l o a t - s i n k f r a c t i o n a t i o n was p e r f o r m e d i n o r d e r t o d e f i n e t h e r e l a t i v e u t i l i t y o f w a s h i n g and chemical d e s u l f u r i z a t i o n f o r each c o a l . The r e s u l t s a r e shown i n c o l u m n 8 and a l s o i n F i g u r e 2. The s u l f u r r e d u c t i o n p o t e n t i a l o f t h e M e y e r s p r o c e s s i s h i g h l y a t t r a c t i v e and i n p a r t i c u l a r i t was found t h a t : (1) The M e y e r s p r o c e s s , a t i t s c u r r e n t s t a t e o f d e v e l o p m e n t , removed 83-99% o f t h e p y r i t i c s u l f u r c o n t e n t o f t h e 32 coals s t u d i e d , r e s u l t i n g i n t o t a l s u l f u r content r e d u c t i o n s o f 25-80%


11.

HAMERSMA

Meyers Process for Desulfurization

E T A L .

APPALACHIAN INTERIOR BASINS WESTERN

Ο Δ •

Ν 24 Ν- 7 Ν -• 4

TOTAL SULPHUR,

% w/w \

\

\


\

Δ

ο

\

Ρ

\

Ο

Δ

\ \

\

\

N

v

ο

° n

Ο Ο

\

v

\ ό

Ο

V , \

^o

OOO

\

S

\ \

co\ L_2 l l _ 0.5

1.0

\

\

_J 1.5

\

\

M . 2.0

2.5

ORGANIC SULPHUR, % W/W

ι

5

6

7

8

Figure 1.

Sulfur forms of sampled U.S. coals

Figure 2. Sulfur content of survey run-ofmine coals (curve a), the same coals physically cleaned (curve c), and chemically de sulfurized (curve b)



Navajo Kopperston No. 2 H a r r i s Nos. 1 & 2 Colstrip Warwick Marion Mathies Isabella Orient No. 6 Lucas Jane Martinka North River Humphrey No. 7 No. 1 Bird No. 3 Williams Shoemaker Meigs Fox Dean Powhattan No. 4 Eagle No. 2 Star Robinson Run

Mine 0..8 0.,9 1.,0 1.,0 1.,4 1.,4 1.,5 1.,6 1.,7 1.,8 1.,8 2.,0 2. ,1 2,,6 3..1 3.,1 3..5 3..5 3,.7 3,.8 4,.1 4..1 4,.3 4,.3 4,.4 0,.6 0,.6 0..8 0,.6 0,,6 0,,7 0,,9 0,,1 0..9 0..6 0,,7 0,.6 0..9 1..5 1..6 0,.8 1..7 1,.7 1,.9 1,.6 2,.1 1,.9 2,.0 2..5 2,.2

0.,5 0..5 0.,6 0.,7 0.,4 0.,6 0.,5 0.,5 0.,8 0.,5 0.,6 0.,8 0.,8 1.,2 1.,4 0.,4 1.,4 1.,5 1,.7 1..2 1,.6 1,.9 1,.9 1,.8 1,.6

% T o t a l S u l f u r w/w i n Coal2 A f t e r Meyers Process Current Revised Initial Results Processing^ 90 92 94 83 92 96 95 96 96 94 91 92 91 91 90 96 96 96 93 89 94 85 94 91 97

25 33 23 30 54 50 36 54 44 64 63 70 55 42 48 75 50 51 48 57 49 53 54 43 50

Meyers P r o c e s s " Pyrite Total S Conv. Decrease (% w/w) (% w/w)

Summary of P y r i t i c S u l f u r Removal Results^(100-150 u t o p - s i z e coal)

Nos. 6,7,8 Campbell Creek Eagle & No. 2 Gas Rosebud Sewickley Upper Freeport Pittsburgh Pittsburgh H e r r i n No. 6 Middle K i t t a n n i n g Lower Freeport Lower K i t t a n n i n g Corona Pittsburgh Mason Lower K i t t a n n i n g Pittsburgh Pittsburgh C l a r i o n 4A Lower K i t t a n n i n g Dean P i t t s b u r g h No. 8 I l l i n o i s No. 5 No. 9 Pittsburgh

Seam

Table I.


1.0 1.2 1.7 1.5 1.4 0.7 0.8 0.8 2.2 1.9 2.3 1.5 2.3 3.6 2.8 2.0 3.0 3.3 2.9 3.0 3.0

0.8 0.9

% Sulfur i n Coal^ After FloatSink


No. 11 No. 9 (W. Ky.) No. 9 Upper F r e e p o r t Meigs Creek Des M o i n e s No. 1 P i t t s b u r g h No. 8

Seam 4.5 4.5 4.8 4.9 6.1 6.4 6.6

Initial

% Total

1.7 2.0 2.8 0.8 3.2 2.2 2.7

1..6 2. ,1 2. ,2 0..5 2. ,7 1. ,7 2. ,1

S u l f u r w/w i n C o a l 2 ~ A f t e r Meyers Process Current Revised Results Processing^ 93 89 91 965 94 92 89

47 55 42 80 47 65 59

Meyers P r o c e s s " Pyrite Total S Conv. Decrease (% w/w) (% w/w) 3,.2 2,.9 3..5 2,.1 4,Λ 3.,9 4.,6

% Sulfur i n Coal^ After FloatSink

moisture-free

Run

using

a t 200 m χ 0.

Calculated

l a t e s t process

improvement.

14 mesh χ 0, i s d e f i n e d

basis.

1.90 f l o a t m a t e r i a l ,

Dry,

here as the l i m i t o f c o n v e n t i o n a l

coal

cleaning.

A 100 g s a m p l e o f c o a l was r e f l u x e d w i t h 2 L o f I N F e 2 ( S 0 4 ) 3 s o l u t i o n . A f t e r 4-6 h r s , t h e r e d u c e d s o l u t i o n was f i l t e r e d f r o m t h e c o a l a n d t h e c o a l was r e f l u x e d w i t h 2 L o f f r e s h I N F e 2 ( S 0 4 ) 3 . A f t e r a t o t a l e x t r a c t i o n t i m e o f 10-24 h r , t h e s l u r r y was f i l t e r e d and t h e c o a l c a k e was washed w i t h 0.2N H2SO4, t h e n w i t h w a t e r t o remove r e s i d u a l s u l f a t e . T o l u e n e (400 m l ) e x t r a c t i o n o f t h e c o a l removed e l e m e n t a l s u l f u r . The c o a l c a k e was t h e n d r i e d i n a vacuum oven a t 100-120°C.

Homestead Camp Nos. 1 & 2 Ken Delmont Muskingum Weldon No. 11 Egypt V a l l e y No. 21

Mine

Table I continued.


148

C O A L DESULFURIZATION

(2)

T w e l v e (38%) o f t h e c o a l s w e r e r e d u c e d i n s u l f u r c o n t e n t to t h e 0.6-0.8% s u l f u r l e v e l s g e n e r a l l y c o n s i s t e n t w i t h t h e F e d e r a l New S o u r c e P e r f o r m a n c e S t a n d a r d s ar»H many s t a t e standards I n a l l c a s e s , t h e M e y e r s p r o c e s s removed s i g n i f i c a n t - t o v e r y l a r g e i n c r e m e n t s o f s u l f u r o v e r t h a t s e p a r a b l e by physical cleaning I n two c a s e s , t h e C o r o n a and M a t h i e s m i n e s , c o a l c l e a n ing a c t u a l l y r e s u l t e d i n a s u l f u r content i n c r e a s e i n the f l o a t product.

(3)

(4)


Rate of P y r i t i c

S u l f u r Removal

The r e m o v a l o f p y r i t i c s u l f u r was measured as a f u n c t i o n o f t i m e a t 100°C f o r 18 A p p a l a c h i a n and 3 e a s t e r n i n t e r i o r r e g i o n coals. The r e s u l t s a r e d i s p l a y e d i n T a b l e I I , w h i c h shows t h e range of r a t e s observed. I t was assumed t h a t t h e e m p i r i c a l k i n e t i c r a t e e x p r e s s i o n (3) w h i c h was d e v e l o p e d p r e v i o u s l y f o r t h i s process i s a p p l i c a b l e to a l l c o a l s i n the survey. The k i n e t i c e q u a t i o n c a n be s i m p l i f i e d by h o l d i n g t h e r e a g e n t c o n c e n t r a t i o n r e l a t i v e l y c o n s t a n t , as was t h e c a s e i n t h i s s t u d y , t o y i e l d E q u a t i o n 2: -d[W ] p

, °τ» 2 _ . = k W = r a t e of p y r i t e D

removal

(2)

dt w h e r e : W = w e i g h t p e r c e n t p y r i t e i n t h e c o a l , and k° = f u n c t i o n of tempeTâture, c o a l t y p e and p a r t i c a l s i z e . By i n t e g r a t i n g E q u a t i o n 2, t h e f r a c t i o n o f p y r i t e removed as a f u n c t i o n o f t i m e i s shown i n E q u a t i o n 3: p

1-F where: F centration, The i n i t i a l f o r WWp ° and n

Ρ

_

(3)

F

f r a c t i o n o f p y r i t e removed, W = i n i t i a l p y r i t e con and t p = t i m e t o r e m o v a l a t T r a c t i o n F. w e i g h t p e r c e n t o f p y r i t i c s u l f u r Sp° may be s u b s t i t u e d E q u a t i o n 3 be r e a r r a n g e d t o E q u a t i o n 4 p

ο k = a c t u a l r a t e constant

(A)

T h u s , a s s u m i n g 80% r e m o v a l as a p o i n t o f c o m p a r i s o n , t h e v a l u e s o f 1/Sp_°_t80% shown i n c o l u m n 6 o f T a b l e I I i n d i c a t e t h e r e a c t i v i t i e s of t h e p y r i t e c o n t a i n e d i n t h e c o a l s t h a t w e r e s t u d i e d . A l a r g e amount o f e x p e r i m e n t a t i o n and e n g i n e e r i n g has b e e n p e r f o r m e d u s i n g r a t e d a t a o b t a i n e d f o r M a r t i n k a (3) c o a l ; t h e r e f o r e , t h e M a r t i n k a c o a l Sp°tftQ% has b e e n s e t e q u a l t o 1 as a b a s i s o f c o m p a r i s o n (as shown i n c o l u m n 7 ) .



Campbell Creek E a g l e & No. 2 Gas Upper F r e e p o r t Middle Kittanning Pittsburgh Pittsburgh No. 9 Corona No. 9 Pittsburgh P i t t s b u r g h No. 8 No. 11 Lower K i t t a n n i n g Pittsburgh Lower K i t t a n n i n g C l a r i o n 4A Lower K i t t a n n i n g Dean M e i g s C r e e k No. 9

Seam 149 149 149 100 149 100 149 149 100 100 75 149 75 149 149 149 100 100 149 0.47 0.49 0.90 1.42 2.19 2.23 2.85 1.42 2.66 1.05 2.75 3.11 3.09 1.07 1.42 2.19 2.87 2.62 3.65

Sp°

forPyritic

Top Size (Microns)

R e l a t i v e Rate Constants

2.0 2.3 3.0 3.25 2.9 3.0 2.5 5.0 3.0 9.0 4.0 3.5 4.5 13.0 10.0 8.5 8.0 10.2 8.0

80% (hrs)

u

Sulfur

1.1 0.89 0.37 0.22 0.16 0.15 0.14 0.14 0.13 0.11 0.091 0.092 0.072 0.072 0.070 0.054 0.044 0.037 0.034

^ % 0 %

1

R e a l t i v e Rate

Removal

16 13 5.3 3.1 2.3 2.1 2.0 2.0 1.9 1.6 1.3 1.3 1.0 1.0 1.0 0.77 0.62 0.53 0.49

Relative Rate

2

Constants

l/S>p_tgQ0£ r e l a t i v e t o v a l u e f o r M a r t i n k a m i n e .

o

As i n f o o t n o t e 1 o f T a b l e I , e x c e p t t o l u e n e e x t r a c t i o n was o m i t t e d . P y r i t e removal r a t e data was o b t a i n e d by p y r i t e a n a l y s i s o f c o a l s a m p l e s o b t a i n e d f r o m s l u r r y a l i q u o t s by c e n t r i f u g a t i o n .

K o p p e r s t o n No. 2 H a r r i s Nos. 1 & 2 Marion Lucas Shoemaker Williams Ken North River Star Mathies P o w h a t t a n No. 4 Homestead Fox Isabella Martinka Meigs B i r d No. 3 Dean Muskingum

Coal Mine

Table I I .


150

DESULFURIZATION


COAL

FLOAT - SINK SEPARATION (FLOAT FRACTION) MEYERS PROCESS

Figure 3.

Trace element removal data


11.

HAMERSMA

E T

AL.

Meyers Process for Desulfurization

151

I t c a n be e a s i l y s e e n f r o m T a b l e I I t h a t t h e r e i s a w i d e band o f r a t e c o n s t a n t s r a t h e r e v e n l y s p r e a d o v e r a f a c t o r o f a p p r o x i m a t e l y 30. The K o p p e r s t o n No. 2 a n d H a r r i s N o s . 1 and 2 c o a l s r e a c t more r a p i d l y t h a n t h e s l o w e s t c o a l s (Dean a n d Muskingum) b y a f a c t o r o f a b o u t 30. T h u s , i t i s a p p a r e n t t h a t r e a l a n d s i g n i f i c a n t r a t e d i f f e r e n c e s do e x i s t b e t w e e n p y r i t e i n various coals. C h a r a c t e r i s t i c s o f c o a l such as pore s t r u c t u r e , s i z e a n d s h a p e d i s t r i b u t i o n o f p y r i t e , e t c . may be t h e p r i m a r y f a c t o r s a f f e c t i n g t h e r a t e c o n s t a n t as r e f l e c t e d i n t h e observed band o f v a l u e s f o u n d f o r t h e r a t e s g i v e n i n T a b l e I I .


T r a c e Element Removals B e c a u s e b o t h c h e m i c a l l e a c h i n g and p h y s i c a l c l e a n i n g p r o c e s s e s c a n remove p o t e n t i a l l y h a r m f u l t r a c e e l e m e n t s f r o m c o a l e i t h e r by l e a c h i n g o r by p h y s i c a l p a r t i t i o n i n g , 50 c o a l s a m p l e s have been a n a l y z e d i n d u p l i c a t e o r t r i p l i c a t e t o determine t h e e x t e n t o f t h e r e m o v a l , i f a n y , o f 18 e l e m e n t s o f i n t e r e s t t o t h e E n v i r o n m e n t a l P r o t e c t i o n A g e n c y . The s a m p l e s i n c l u d e d 20 a s r e c e i v e d , 20 c h e m i c a l l y l e a c h e d , and 10 f l o a t - s i n k t r e a t e d c o a l s a m p l e s . The r e s u l t s a r e shown f o r 12 e l e m e n t s i n F i g u r e 3 i n cumulative fashion. The e x t r a c t i o n p r o c e d u r e was a s i n T a b l e I . S i x e l e m e n t s , B, B e , Hg, Sb, Se, and Sn y i e l d e d n e g a t i v e o r i n c o n c l u s i v e r e s u l t s because of low l e v e l s o r a n a l y s i s d i f f i c u l t i e s and t h u s a r e n o t p l o t t e d . A l t h o u g h t h e r e s u l t s v a r i e d g r e a t l y f r o m c o a l t o c o a l w i t h r e s p e c t t o t h e e l e m e n t s e x t r a c t e d and t h e d e g r e e o f e x t r a c t i o n , some g e n e r a l c o n c l u s i o n s c a n be r e a c h e d . (1) A s , C d , Mn, N i , P b , and Zn a r e removed t o a s i g n i f i c a n t l y g r e a t e r e x t e n t by t h e Meyers p r o c e s s (2) F and L i a r e p a r t i t i o n e d t o a g r e a t e r e x t e n t by p h y s i c a l separation procedures. (3) Ag a n d Cu a r e removed w i t h a s l i g h t p r e f e r e n c e f o r f l o a t - s i n k separation (4) C r a n d V a r e removed by b o t h p r o c e s s e s w i t h e q u a l success. The e f f e c t i v e r e m o v a l o f A s , C d , C r , N i , P b , and Zn f r o m t h e c o a l b y t h e M e y e r s p r o c e s s i s e s p e c i a l l y n o t e w o r t h y a s t h e s e compounds a r e c o n c e n t r a t e d ( a l o n g w i t h Se) i n t h e f i n e p a r t i c u l a t e s e m i t t e d f r o m c o a l - f i r e d power p l a n t s . This f i n e p a r t i c u l a t e matter passes through conventional f l y - a s h c o n t r o l devices.

Literature Cited

1. Meyers, R.A., Hamersma, J.W., Land, J.S., Kraft, M.L., Science, (1972),177,1187. 2. Meyers, R.A., "Removal of Pyritic Sulfur from Coal Using Solutions Containing Ferric Ions," U.S. Patent 3768988, 1973. 3. Koutsoukos, E.P., Kraft, M.L., Orsini, R.A., Meyers, R.A., Santy, M.J., Van Nice, L.J., "Final Report Program for BenchScale Development of Processes for the Chemical Extraction of


152 4. 5.


6. 7. 8.

9. 10.

COAL DESULFURIZATION

Sulfur from Coal," Environ. Prot. Technol. Ser., (May 1976), EPA-600/2-76-143a. Hamersma, J.W., Koutsoukos, E.P., Kraft, M.L., Meyers, R.A., Ogle, G.J., Van Nice, L.J., "Chemical Desulfurization of Coal: Report of Bench-Scale Developments, Volumes 1 and 2," Environ. Prot. Technol. Ser., (February 1973),EPA-R2-173a. Magee, E.M., "Evaluation of Pollution Control in Fossil Fuel Conversion Processes, Coal Treatment: Section 1. Meyers Process," Environ. Prot. Technol. Ser., (September 1975), EPA-650/2-74-009k. Nekervis, W.F., Hensley, E.F., "Conceptual Design of a Commercial Scale Plant for Chemical Desulfurization of Coal," Environ. Prot. Technol. Ser. (September 1975), EPA-600/2-75-051. Tek, M. Rasin, "Coal Beneficiation," in Evaluation of Coal Conversion Processes, (1974) PB-234202. U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC, "Applicability of the Meyers Process for Chemical Desulfurization of Coal: Initial Survey of Fifteen Coals," by J.W. Hamersma et al, Systems Group of TRW, Inc., Redondo Beach, CA. (April 1974), EPA-650/2-74-025, Contract No. 68-02-0647. Hamersma, J.W., Kraft, M.L., "Applicability of the Meyers Process for Chemical Desulfurization of Coal: Survey of Thirty-Five Coals," Environ. Prot. Technol. Ser., (September 1975), EPA-650/2-74-025a. Deurbrouck, A.W., "Sulfur Reduction Potential of Coals of the United States," U.S. Bur. Mines Rep. Invest. (1972), 7633.


Coal Desulfurization

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