Methane emission from U.S. coal mines : a survey

Abstract

ILLUSTRATIONS . . . . . . . . . . . . . . . . . . . . . . . . C o a l f i e l d s o f t h e c o n t e r m i n o u s U n i t e d S t a t e s 3 Remaining c o a l r e s o u r c e s o f t h e U n i t e d S t a t e s a s d e t e r m i n e d by mapping and e x p l o r a t i o n . J a n u a r y 1. 1967 . b y S t a t e . a c c o r d i n g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . t o t o n n a g e and h e a t v a l u e 4 T o t a l r e m a i n i n g s t r i p p a b l e r e s o u r c e s and r e s e r v e s o f c o a l and . . . . . . l i g n i t e i n t h e U n i t e d S t a t e s . by r a n k . a s o f J a n u a r y 1. 1968 5 Remaining s t r i p p a b l e r e s o u r c e s and r e s e r v e s o f c o a l and l i g n i t e . . . . . i n t h e U n i t e d S t a t e s . by c o a l p r o v i n c e . a s o f J a n u a r y 1. 1968 6 E f f e c t o f a n i d l e p e r i o d on t h e me thane e m i s s i o n r a t e o f a n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . o p e r a t i n g mine i n P e n n s y l v a n i a 7 . . . . . . . . . . . . . . . . . L o c a t i o n s o f a c t i v e m i n e s i n t h e P i t t s b u r g h c o a l b e d 8 Methane e m i s s i o n r a t e and a v e r a g e d e p t h o f m i n e s i n t h e I l l i n o i s Nos . 5 and 6 c o a l b e d s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Methane e m i s s i o n and c o a l p r o d u c t i o n r a t e s o f m i n e s i n t h e . I l l i n o i s Nos 5 and 6 c o a l b e d s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Methane e m i s s i o n r a t e a n d a g e o f m i n e s i n t h e P i t t s b u r g h c o a l b e d . . . . 11 Methane e m i s s i o n r a t e v e r s u s c o a l p r o d u c t i o n r a t e t i m e s d e p t h f o r m ines i n t h e P i t t s b u r g h c o a l b e d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Methane e m i s s i o n r a t e v e r s u s c o a l p r o d u c t i o n r a t e t i m e s d e p t h . f o r m i n e s i n t h e P o c a h o n t a s Nos 3 and 4 c o a l b e d s . . . . . . . . . . . . . . . . . 1 3 Methane e m i s s i o n r a t e v e r s u s c o a l p r o d u c t i o n r a t e t i m e s d e p t h . f o r m i n e s i n t h e I l l i n o i s Nos 5 and 6 c o a l b e d s . . . . . . . . . . . . . . . . . . . 1 4 METHANE EMISSION FROM U.S. COAL MINES, A SURVEY M. C. lraniI1 E. D. ~ h i r n o n s , ~ T. G. Bobickll Maurice ~ e u l , ~ and M. G. zabetakis4 ABSTRACT This su rvey was conducted t o de te rmine t h e magnitude o f t h e methane emiss ion and c o n t r o l problem i n U.S. bituminous c o a l mines. The r e s u l t a n t d a t a i n d i c a t e t h a t t h e emiss ion r a t e f o r any g iven coa lbed depends p r i m a r i l y on t h e c o a l p roduc t ion r a t e and on mine d e p t h , a s w e l l a s on t h e n a t u r e o f t h e coa lbed and t h e su r rounding s t r a t a . An e x c e l l e n t c o r r e l a t i o n was found between (1) t h e methane emiss ion r a t e and (2) t h e product o f c o a l p roduc t ion r a t e and mine dep th f o r t h e mines i n t h e P i t t s b u r g h , Pocahontas Nos. 3 and 4 , and t h e I l l i n o i s Nos. 5 and 6 coa lbeds .This su rvey was conducted t o de te rmine t h e magnitude o f t h e methane emiss ion and c o n t r o l problem i n U.S. bituminous c o a l mines. The r e s u l t a n t d a t a i n d i c a t e t h a t t h e emiss ion r a t e f o r any g iven coa lbed depends p r i m a r i l y on t h e c o a l p roduc t ion r a t e and on mine d e p t h , a s w e l l a s on t h e n a t u r e o f t h e coa lbed and t h e su r rounding s t r a t a . An e x c e l l e n t c o r r e l a t i o n was found between (1) t h e methane emiss ion r a t e and (2) t h e product o f c o a l p roduc t ion r a t e and mine dep th f o r t h e mines i n t h e P i t t s b u r g h , Pocahontas Nos. 3 and 4 , and t h e I l l i n o i s Nos. 5 and 6 coa lbeds . The h i g h e s t t o t a l emiss ion r a t e s found i n U.S. bituminous c o a l mines were a s f o l l o w s , i n m i l l i o n c u b i c f e e t per day: Monongalia County, W . Va., 39; Marion County, W . Va., 30.4; McDowell County, W . Va., 13.1; Washington County, Pa. , 11.9; Greene County, Pa. , 11.4; Buchanan County, Va., 21.6; J e f f e r s o n County, A l a . , 10.3; and F r a n k l i n County, Ill., 6.6 . 1 Methane i n a i r h a s long been a hazard t o mine s a f e t y because o f i t s 1 1 e x p l o s i v e q u a l i t i e s , and t h e Bureau of Mines has engaged i n methane s t u d i e s 1 s i n c e i t s e s t a b l i s h m e n t i n 1910. One o f t h e e a r l i e s t s t u d i e s was a c t u a l l y begun i n 1907 under t h e immediate s u p e r v i s i o n o f D r . J . A. Holmes, who subsequen t ly became t h e f i r s t d i r e c t o r of t h e Bureau o f mine^.^ That s t u d y was made t o o b t a i n i n f o r m a t i o n on t h e o r i g i n o f t h e inflammable gases i n c o a l and t h e c o n d i t i o n s under which t h e y occur . Data were o b t a i n e d from t h e a n t h r a c i t e f i e l d s i n Pennsylvania and t h e s o u t h e r n bituminous f i e l d s i n I l l i n o i s . lMining eng ineer . 2 P h y s i c i s t . 1 3Supervisory g e o l o g i s t . I 4Superv i sory r e s e a r c h chemis t . 1 Dar ton, N. H. Occurrence o f Explos ive Gases i n Coal Mines. BuMines B u l l . 7 2 , 1915, 248 pp. The e x t e n t t o which methane gas emiss ion w i l l be a problem i n t h e f u t u r e , e s p e c i a l l y i n t h e underground mining o f subbituminous c o a l s and l i g n i t e s , has n o t y e t been determined. However, t h e d a t a p resen ted i n t h i s r e p o r t shou ld a s s i s t i n p lanning new mine development i n the v i c i n i t y o f o p e r a t i n g mines f o r which methane emiss ion r a t e s a r e known and i n planning e f f e c t i v e methane c o n t r o l procedures . ACKNOWLEDGMENTS The a u t h o r s e x p r e s s t h e i r a p p r e c i a t i o n t o t h e d i s t r i c t and s u b d i s t r i c t managers, s u p e r v i s o r s , and i n s p e c t o r s of t h e Coal Mine Heal th and S a f e t y branch o f t h e F e d e r a l Bureau o f Mines, who w i l l i n g l y c o n t r i b u t e d t h e i r t ime and exper ience . The s u c c e s s f u l complet ion o f t h i s s t u d y would n o t have been p o s s i b l e w i t h o u t t h e i r c o o p e r a t i o n . F u r t h e r , s p e c i a l c r e d i t i s due Miss Rose Marie Como, who c o l l e c t e d and t a b u l a t e d in format ion from F e d e r a l mine i n s p e c t i o n r e p o r t s , and t o M r . James L. Joyce , who checked t h e t a b u l a t e d d a t a and prepared many of t h e graphs inc luded here . DESCRIPTION OF U.S. COALBEDS Geographical D i s t r i b u t i o n Geograph ica l ly , c o a l i s found i n t h e conterminous Uni ted S t a t e s border ing t h e A t l a n t i c and P a c i f i c Oceans, t h e Gulf o f Mexico, Mexico, and t h e Dominion of Canada; i t i s found i n t h e mountain p r o v i n c e s , t h e C o a s t a l P l a i n s , and t h e n o r t h e r n Great P l a i n s . Although c o a l mining i s commonly known t o be a major i n d u s t r y o n l y i n Appalachia and t h e c o a l b a s i n s of I l l i n o i s I n d i a n a , c o a l i s now being mined i n 24 of t h e 34 conterminous S t a t e s which have s i g n i f i c a n t c o a l r e s o u r c e s . According t o A v e r i t t Y G c o a l b e a r i n g rocks u n d e r l i e about 1 4 percen t of t h e l a n d a r e a of t h e 48 conterminous S t a t e s . F igure 1, f a m i l i a r t o most persons concerned w i t h c o a l r e s o u r c e s , shows t h e geographic d i s t r i b u t i o n o f U . S . c o a l f i e l d s . However, i t i s more u s e f u l t o examine t h i s map i n c o n j u n c t i o n w i t h f i g u r e 2 , a l s o from A v e r i t t Y 7 which shows t h e d i s t r i b u t i o n of t h e remaining c o a l r e s o u r c e s i n t h e v a r i o u s S t a t e s . Coal Resources and Methane Emission A l l coalbeds c o n t a i n methane. This gas i s formed from p l a n t m a t e r i a l s by biochemical and b a c t e r i a l t r a n s f o r m a t i o n s dur ing t h e peat s t a g e of c o a l d e p o s i t i o n and subsequen t ly by metamorphic p rocesses as b u r i e d peat i n c r e a s e s i n rank t o become c o a l . Because of t h e f i n e pore s t r u c t u r e o f c o a l and degraded p e a t , t h e s o r p t i v e c a p a c i t y o f such subs tances i s v e r y l a r g e so t h a t much of t h e methane evolved d u r i n g c o a l i f i c a t i o n i s h e l d i n t h e pea t and i n t h e c o a l . The a c t u a l amount of methane r e t a i n e d i n t h e c o a l depends a l s o G A v e r i t t , Pau l . Coal Resources of t h e United S t a t e s January 1, 1967. U.S. Geol. Survey B u l l . 1275, 1969, 116 pp. ?Work c i t e d i n f o o t n o t e 6 . FI G U R E 1 . C o a lf ie ld s o f th e C o n te rm in o u s U n it e d S ta te s. COAL HESOTTIICES O F T H E UNITED STATES BILLIONS OF SHORT TONS 100 QUADRILLIONS OF BRITISH THERMAL UNITS 1