Bureau of Mines Report of Investigations/ 1973 

Methane Control by Isolation of a Major 

Coal Panel-Pittsburgh Coalbed 

UNITED STATES DEPARTMENT OF THE INTERIOR 
Report of Investigations 7790 

Methane Control by Isolation of a Major 

Coal Panel-Pittsburgh Coalbed 

By Charles Findlay, Stephen Krickovic, and J. E. Carpetta 

Pittsburgh Mining and Safety Research Center, Pittsburgh, Pa. 

UNITED STATES DEPARTMENT OF THE INTERIOR 

Rogers C. B. Morton, Secretary 

BUREAU OF MINES 

John D. Morgan, Jr., Acting Director 

The work upon which this report is based was done under a cooperative agreement between the Bureau of Mines, 

U.S. Department of the Interior, and the Eastern Associated Coal Corp. 
This publication has been cataloged as follows: 

Findlay, Charles 

Methane control by isolation of a major coal panel-Pittsburgh coalbed, by Cha-rles Findlay, Stephen Krickovic, and 

J. E. Carpetta. [Washington] U.S. Bureau of Mines [1973] 

11 p., illus., tables, (U.S. Bureau of Mines. Report of investigations 7790) 

Based on work done in cooperation with Eastern Associated 

Coal Corp. 

1. Methane. 2. Mine gases. 3. Mine ventilation. 1. Krickovic, 

Stephen, jt, auth. 11. Carpetta, John E., jt. auth. 111. U.S, Bureau 

of Mines. IV. Title. (Series) 

TN23.U7 no. 7790 622.06173 

U.S. Dept. of the Int, Library 

* 
CONTENTS 

Page 

Abstract ................................................................. 1 

Introduction ............................................................. 1 

Acknowledgments .......................................................... 2 

Description of the study areas ........................................... 2 

Mining method and equipment .............................................. 3 

Ventilation .............................................................. 4 

Monitoring .......................................................... 5 

Results .................................................................. 5 

Isolated panel ...................................................... 5 

Virgin coal areas ................................................... 10 

Discussion ............................................................... 10 

ILLUSTRATIONS 

Location of study areas .............................................. 3 

Data from study area 1-- isolated panel ............................... 7 

Data from study area 2 - - 2 North mains ................................ 7 

Data from study area 3-. isolated panel ............................... 8 

Data from study area 4-- isolated panel ............................... 8 

Data from study area 5-- isolated panel ............................... 8 

Data from study area 6.. isolated panel ............................... 9 

Data from study area 7-. 2 South mains ................................ 9 

Data from study area 8-- isolated panel ............................... 10 

TABLE S 

1 . Data on mining layout in study areas ................................. 4 

2 . Summary of pertinent data from methane emission studies in the 

isolated panel of coal and in two virgin areas ..................... 6 
METHANE CONTROL BY ISOLATION OF A MAJOR COAL 

PANEL-PITTSBURGH COALBED 

b Y 

Charles Findlay, 1 Stephen Krickovic,2 and J. E. Carpetta3 

ABSTRACT 

As one of its projects for degasification of major panels of coal prior 

to mining within them, the Bureau of Mines conducted methane emission studies 

during development of a set of three headings 1,800 feet in a major coal panel 

(2,700 by 3,500 feet) which had been completely isolated by sets of main headings for 12 months in the Federal No. 2 mine (Pittsburgh coalbed) in northern 

West Virginia. Similar emission studies were conducted in the development of 

two sets of main headings in virgin coal areas nearby. Comparing the two sets 

of data indicated that the isolated coal panel had been degasified by approximately 70 percent. 

INTRODUCTION 

Methane exists under pressure in micropores, joints, and fractures of 

gassy coalbeds. In many mines it is also present in adjacent strata at various distances above and below the coalbed. An in situ gas pressure as high as 

275 psi has bccn measured in the Pittsburgh coalbed, and the permeability of 

the bed is relatively high.4 Because of this high pressure and permeability, 

it is advantageous from the standpoints of safety and productivity to degasify 

the coalbed as completely as possible before mining it. One procedure for 

draining methane from virgin coalbeds is to isolate major coal panels by developing sets of headings around them and to allow bleed-off for at least 1 year 

prior to mining within the panels. 

Some coal companies have achieved and are achieving almost complete isolation without actually planning the technique. The usual reasons for developing sets of headings in areas adjacent to those being mined, and thereby 

obtaining a helpful degree of isolation, are ventilation problems, difficult 

mining conditions, and the need for greater production. In the relatively few 

cases where total isolation is planned, mining within the isolated panel is 

lMining engineer (now retired) . "Supervisory mining engineer. 3 Mining engineering technician. 

4~ervik, Joseph. An Investigation of the Behavior and Control of Methane Gas. 

Min. Cong. J., v. 53, July 1967, pp. 52-57. 
started immediately upon completion of the isolation. Although this does 

improve safety and productivity to some degree, more time should be allowed 

for methane bleed-off. 

In other cases of mining in very gassy coalbeds, sets of headings are 

developed for longwall panels ahead of need to obtain some benefit from isolation, but more importantly to facilitate drilling degasification holes in the 

coalbed on both sides of the established longwall block. 

Isolation of coal panels as a means of degasifying very gassy coalbeds 

adequately in advance of mining within the panels is an essential part of the 

Bureau's comprehensive methane control program. The objective of this study 

was to determine the quantity of methane that had drained from the 2,700- by 

3,500-foot panel of Pittsburgh coal that had been completely isolated for 

12 months in Federal No. 2 mine, Eastern Associated Coal Corp., and to develop 

data that would lead to a well-defined technology suitable for transfer to the 

coal mining industry. 

ACKNOWLEDGMENTS 

The cooperation of Eastern Associated Coal Corp. in conducting the various studies at their Federal No. 2 mine is greatly appreciated. 

DESCRIPTION OF THE STUDY AREAS 

Methane emissions were monitored at eight areas in Federal No. 2 mine 

(fig. 1): 

Area 1 was located in the development of four headings of the 2 South 

mains to complete the set of ten 2 South mains headings of the 2,700- by 

3,500-foot panel which had been totally isolated approximately 12 months 

before mining was started within it. Area 2 was located in six of the projected set of ten 2 North mains headings. The six headings had been developed 

1,700 feet in virgin coal north of 1 East mains and the isolated panel. 

Areas 3, 4, 5, 6, and 8 were located in a set of three headings being 

developed in the isolated block to improve ventilation. Areas 1, 3, 4, and 5 

were approximately 400 feet apart, and areas 5, 6, and 8 were 300 feet apart. 

Thus, the length of the set of three headings studies was 1,800 feet of the 

2,700-foot length of the short side of the block. 

Area 7 was located in seven of the projected ten 2 South mains headings. 

These headings had been developed a distance of 1,000 feet south of the isolated block. 

Development of the four sides of the isolated coal panel had been completed on the following dates: North airways near the coal shaft bottom, 

January 1, 1969; 1 East mains and East airways, January 1, 1970; and 2 South 

mains, April 1, 1971. When mining was started within the panel, the first 

side had been developed for 3-114 years, and the other two sides on the east 

and west courses for 2-114 years. 
FIGURE 1. - Location of study areas. 

MINING METHOD AND EQUIPMENT 

The number of headings in a set, the centers and widths of headings and 

breakthroughs, and the angles of the breakthroughs with respect to the headings in the study areas are shown in table 1. 

The coalbed was 9 feet thick, 7 feet of which was mined. The depth of 

the overburden ranged from 735 to 845 feet. Boring-type continuous miners 

were used in all study areas except area 7, where a full-face ripper-type unit 
was used. Mined coal was discharged from the booms of the miners to the floor, 

transferred by conventional loaders into 10-ton-capacity shuttle cars and from 

there to the tail ends of belt conveyors. Generally, two shuttle cars serviced each continuous miner. The roof was supported by steel bolts with 

expansion shells, installed with a hydraulic drill. 

TABLE 1. - Data on mining layout in study areas 

lStudy areas 1, 2, and 7 had breakthroughs at right angles to the 

heading, while study areas 3, 4, 5, 6, and 8 had breakthroughs 

angled 60 degrees on both sides of the middle heading. 

Study 

area1 

1 

2 

3 

4 

5 

6 

7 

8 

VENTILATION 

Three of the four headings in area 1 were used for intake air, with the 

air splitting in the inby line of open breakthroughs from the middle intake 

heading. The right split returned through the fourth heading toward the 

entrance to the section, and the left split through the existing adjacent 

heading of the set of six headings driven previously. The flow was in the 

oppositedirection from that of the first air split. Total airflow was 38,000 

cubic feet per minute (ch) , with 16,000 cfrn in the left split and 22,000 cfrn 

in the right split. The continuous miner was operated in both splits during 

the study. 

In area 2, four headings were used for intake air, with the flow in the 

belt heading regulated to roughly 3,000 cfm. The total intake of 78,000 cfrn 

was split left and right in the last inby line of open breakthroughs. Single 

headings on either side were used to return the air splits, with an average of 

46,000 c£m in the right split and 32,000 c£m in the left. The continuous 

miner was operated in the lower volume split. The ventilation plan in area 7 

was essentially the same as that in area 2, except that two headings were used 

for return air on the left side (airflow of 47,000 cfm) and one on the right 

side (airflow of 35,000 cfrn), where the continuous miner was operated. 

Number of 

headings in 

a set 

4 

6 

3 

3 

3 

3 

7 

3 

In areas 3, 4, 5, 6, and 8, the left heading was used for intake air and 

the right heading for return air. A belt conveyor was installed in the 

middle heading, where the intake air was regulated to roughly 3,000 cfm. The 

total intake airflow ranged from 29,000 c£m in study area 3 to 35,000 cfrn in 

study area 8. 

Breakthrough 

centers, ft 

90 

80 

8 0 

8 0 

80 

8 0 

9 0 

80 

Heading 

centers, ft 

9 0 

9 0 

100 

100 

100 

100 

100 

100 

Width of headings 

and breakthroughs, 

ft 

13 

13 

13 

13 

13 

13 

14 

13 
In all areas, auxiliary fans and reinforced tubing were used to ventilate 

the heading or breakthrough where the continuous miner worked. After completing mining in one place and tramming to another, line brattice was hung in the 

place just finished in the cycle. Exceptions occurred only when a breakthrough was completed between two adjacent headings, when arrangements were 

made to conduct the air through the breakthrough. 

In preparation for the gas emission measurements, ventilation and haulage 

arrangements were observed in each study area and plotted on the area maps. 

Air and methane monitoring stations were then established. 

In areas 1, 2, and 7, four men were employed as follows: A mining engineer to time study the operation of the continuous miner, note the number of 

shuttle cars loaded, and generally supervise the work; two mining engineering 

technicians to measure the cross-sectional areas of the established stations, 

to measure the return airflows by traversing uniformly the cross-sectional 

areas every hour with an anemometer and to measure with a hand-held methanometer the percent methane at the point of average velocity at 5 to 10 minute 

intervals; and one mining engineering technician to measure the intake airflows and percent methane in the same way as for the return airflows, and to 

note any changes in the ventilation arrangement during each shift. 

To assure the use of the same procedures and thereby eliminate possible 

significant errors, monitoring was conducted by the same personnel in all 

studies. In study areas 3, 4, 5, 6, and 8 within the isolated panel, a mining 

engineer and two mining engineering technicians performed the work described 

above. 

All instruments were checked and calibrated before each study and checked 

again after the study. Duplicate instruments were carried for checking during 

the studies to correct for unavoidable changes in calibration of any 

instrument. 

RESULTS 

The methane content in the intake air and in the immediate returns of 

operating and idle air splits of each study area are shown in figures 2 to 9. 

Pertinent data are summarized in table 2. 

Isolated Panel 

Particularly significant is the trend of methane emission as mining progressed in the isolated panel along a distance of 1,800 feet. Emission 

increased from 2.1 cubic feet per ton of coal mined in area 1 to 14 cubic feet 

in area 4 (800 feet from 2 South mains). At the end of the remaining 1,000 

feet, emission dropped to 6 cubic feet per ton of coal mined. It is anticipated that the rate will be near zero just before cutting through to the 

North airways, where methane had been bleeding off for 3-112 years when 

monitoring was started. 
TABLE 2. - Summary of pertinent data from methane emission studies in the 

of coal and in two virgin areas 

NOTE.--Each area was studied during one operating shift. Air volumes in both activ

were combined in study area 1, to more closely correspond to the three head

split in all other study areas. 

Date of 

study 

2-23-72 

4-13-72 

5-16-72 

6-14-72 

7-20-72 

9-01-72 

3-22-72 

8-07-72 

'~11 study areas except 2 and 7 are in the isolated panel; study areas 2 and 7 are 

2~11 study areas in isolated panel were ventilated with one split air, except area 

four headings . 3~oring-type continuous miner used. Cut cross-sectional area of 80 sq ft. 

40perating air split; two splits in section--total volume 79,000 cfm. 

5 

Operating air split; two splits in section--total volume 82,000 cfm 

'~i~~er-t~~e continuous miner used. Cut cross-sectional area of 100 sq ft. 

Study 

area1 

1 

3 

4 

5 

6 

8 

2 

7 

Average 

total 

air 

volume, 2 

cfm 

38,000 

32,000 

34,000 

32,000 

35,000 

32,000 

432,000 

535,000 

Average methane 

emission volume, 

c fm 

Raw coal 

production, 

net tons 

330 

350 

350 

207 

203 

2 24 

240 

. 88 

Intake 

75 

81 

80 

88 

87 

96 

32 

33 

Continuous 

miner 

operating 

time, 

minutes 

113 

110 

94 

7 6 

104 

6 0 

90 

6 0 

Return 

6 

4 0 

5 2 

30 

17 

2 2 

9 0 

62 

Total 

8 1 

121 

132 

118 

104 

118 

122 

95 

Average 

coal 

production, 

tons per 

minute 

2.92 

3.18 

3.73 

2.72 

1.95 

3.73 

2.67 

1.47 

Aver

meth

emis

cu ft 

ton 

coal 

2

12

14

1

8

6

33

42
KEY 

Mining machine operating; total productlon 330 tons 

0.40 

Methane. cfrn 

Intake air volume 38,000 cfrn 

~~~O~~~~~~JIIIIIJII~II~~~~LII~III~~~I

- 0.40- 0 

n Methane, cfm 

...... .. 

No. I return heading air volume 22,000 cfrn 

IllllllllllllllllllIIIIII~IIIIIIIIIIII11111'11111111111 

No. 5 return heading air volume 16,000 cfrn 

l1111ll11111l11111111111l111111111111/IJ111111111111111 

9:30a.m. 10:OO 10:30 11:OO 11:30 12:00 12:30 1:OO 1:30 2 :00p.m. 

TlME 

FIGURE 2. - Data from study area l-isolated panel. 

KEY 

Gassed out 

M~n~ng mochlne operat~ng:totol productlon 240 tons 

040 7 I 

Intake air Methane, cfm Air vdume, 79,000 cfm 

No. 6 return heading C 

Methane, cfrn 

k? 

Air volume, 47,000 cfm -I 

No. I return heading Methane, cfm Air volume, 32,000 cfm 

Jl~l~~llllllll~l/llIllIIII11l111111lIIIIIIIIIJIIIIIIIIIlIIIII 

9:OOa.m. 930 10:OO 10:30 1 I:OO 11'30 12:OO 12'30 1:Oo I :X) 2:OOp.m. 

TlME 

FIGURE 3. - Data from study area 2-2 North mains. 
KEY 

M~n~ng machlne operatlng: total producf~on 350 tons ncn- - 

Methane. ctm 

T' Intake air volume 32,000 ctm w I0 IllllllllllllllillIIl~l~llll~11~~1111~~~11~~~

lllllllllllllllllllllltl111111lIl/llllllJlll/lllll1ll111l1111 

Return otr volume 32.000 ctm 

830am 900 930 1000 1030 1100 IIX) 1200 1230 100 130 200 2X)pm 

TlME 

FIGURE 4. - Data from study area 3-isolated panel. 

KEY 

::Mining machine operating1 total product~on 350 tons n " 6n. 

U" 

30- 

T' 

w 10 

FIGURE 5. - Data from study area 4-isolated panel. 

Methone, cfm D N 

1 I 

0 - Intake olr volume 34,000 cfm No I Intake heodlng 

I~~~~~I~. Memage,cfrn 0 (0 - - 5 g r) E g ; n 

40- 1 I ! p 0 I - 

KEY 

20- 

M~n~ng mach~ne operatlng: total producl~on 207 tons 

0501- 1 

Return olr volume 34,000 cfm No3 return head~ng - 

111111I11111l11111l11111111111111111111111111111l11111111~11ll11111111111 

Merhone, cfm -1 r 

900am 930 1000 1033 1100 1130 1200 1230 100 130 200 230 300pm 

TlME 

30- I 

FIGURE 6. - Data from study area 5-isolated panel. 

.. 

U 

- 

W 

T 

No I Intake headtng olr volume 32,000 cfm 

WIO.lI1I111II~~IIII~111~~I~~1~ 

- t-zl r;l rq I---- -- N -

40-033~~z~~z-C:~ 3Cp=^Y'*: - 

No 3 return heading olr vdume 32,000 cfm - 

201IiI1IIl1IilIIII~11II1lIII1II~ 

7 

900am 930 1000 1030 1100 I130 1200 1230 100 130 200 230 300pm 

TlME 
KEY 

Min~ng machine operating: total production 203 tons 

0 50 

Methane, cfm 1 C I m 11 

No 3 return alr volume 35.000 cfm 111l1111l11111111l1llllllll/i/ ll 

9:30a.m 1000 10 30 11:OO 11:30 12.00 12-30 1.00 1.30 2:00 2:30 3'00pm. 

TI ME 

30- 

- 

:: 

w-lo 

FIGURE 7. - Data from study area 6-isolated panel. 

1 I - 

- - No I make olr volume 35.000 cfrn IIIII1I1lIIllI111IIIIllIIlI I ,I 

KEY ......... .iiiii.i.it. ......... Mining machine opemting; total production 88 tons 

0.201 

Z 

.......... ....... ........ ....... ...... ..... ... 

lntoke air volume 82,000 cfrn 

..... E ........ :;;:;:;;: ;G$; :>: :; 3 .: .... .:: ..:.:._:_: :.:.: ':':':.:.:.. 

................... .:.:.: ..:. .:.:.: ..:.:. .... ) j:; .33 , .:.:.:..:.:. .I0 .....:..: : ,.. ;:;:;:;:;:; ?;: :; .:. ...... I ............ ,, .:.:.:.:. :.:.:.:.:.:. ..... ... :.:.:. ~ ...... ...... ..... ..... ........... ...... ..... ..:.:.:.:.> .:.: .:.:.:... :.:.:.:.:.:. 

t Methane, cfrn 1 

No. 7 return air volume 35.000 cfrn 

1 No. I return air volume 47,000cfm 

TIME 

FIGURE 8. - Data from study area 7-2 South mains. 

The highest and lowest average methane emission rates were observed in 

areas 4 and 1, respectively (table 2). In area 4 (fig. 5), the equivalent 

maximum methane concentration in the immediate return of the air split was 

0.40 percent (136 cfm) during two different periods (11:OO to 12:00 a.m. and 

1:50 to 3:00 a.m.) with the intake methane included, and 0.21 percent (71 cfm) 

in the first period and 0.10 percent (34 ch) in the second period without the 

intake methane. In area 1 (fig. 2), the maximum concentration occurred during 
KEY 

Mlnlng rnach~ne operat~ng: total productcon 224 tons 

0 60r - I 

Methane, cfrn 

No I intake alr volume 32,000 cfrn 

11llII11.111111~~ 1111111 

.m111IIIl111i1llI1Ill!IlIlI~~~~~

9:30a.m. 10:OO 10:30 11:OO 11:30 12.00 12.30 1:OO 1:30 2:OO 2 30p.m. 

TIME 

a 

I0 60 

FIGURE 9. - Data from study area 8-isolated panel. 

tW 

f 

,othe last 30 minutes of the shift. The methane concentration was 0.24 percent 

(88 cfm) with the intake methane included, and 0.04 percent (12 cfm) without 

the intake methane. 

- Methane, cfm - 

al i=- 

m m -1 p.. ,,,,:,!:; 

N- 

- I - 

- r7J.L / - 

No 3 return air volume 32,000 cfrn 

In area 8 (fig. 9) , 900 feet from the first developed set of headings of 

the isolated panel (North airways), the maximum methane concentration was 0.40 

percent (128 cfm) during one period (12:lO to 2:30 p.m.) with the intake methane included and 0.10 percent (32 cfm) without the intake methane. As already 

mentioned, it is expected that the concentrations without methane from the 

intake air will drop to virtually zero when the North airways are intersected. 

Virgin Coal Areas 

Considering only the operating air split of 32,000 cfrn in area 2 (fig. 3) 

within virgin coal, the highest average methane concentrations for 40 minutes 

in the immediate return airways with and without the intake methane were 0.40 

and 0.30 percent, respectively. Despite this acceptable methane concentration, 

the methane detector mounted on the continuous miner approximately 10 feet 

ahead of the operator stopped the miner 19 times, for a total of 36 minutes, 

at 2.0-percent concentration. 

In the operating air split of 35,000 c£m in area 7 (fig. 8) within virgin 

coal, the highest average methane concentrations for 60 minutes in the imrnediate return airways with and without the intake methane were 0.30 and 0.25 percent, respectively. There were no automatic stoppages of the miner by the 

methane detector such as occurred in area 2, because the long shuttle car 

haulage from the miner resulted in a slow rate of mining. During the period 

of highest methane emission in the operating air split in area 7 (105 cfrn), 

the idle split contained even more methane (110 c£m). Two gas wells nearby 

undoubtedly contributed to the increased flow. 

DISCUSS ION 

Mining within a major panel of coal which had been completely isolated 

for 12 months showed a significant and generally uniform reduction in methane 

emission rates as mining progressed within the panel (table 2). These methane 
reductions are represented both as cubic feet per minute, and as cubic feet 

per ton of coal mined. Comparing the average of 28 cfm (table 2) liberated in 

the six areas within the isolated panel with an average of 76 (90 and 62) cfm 

in the virgin areas 2 and 7 indicates that the methane content in the isolated 

panel had been reduced by 63 percent. Similar comparison of the average of 

9.lcubic feet per ton of coal mined in the isolated panel with the average of 

38 (33.8 and 42.2) cubic feet in the two virgin areas showed a methane reduction of 76 percent. In either case, the weighted average production rate of 

3.00 tpm in the isolated panel could have been doubled without exceeding the 

methane concentration in the immediate return airway. 

It is noteworthy that the methane volume in the intake air conducted in 

all study areas averaged 85 cubic feet per minute (figs. 2-9 and table 2). 

This significant volume bled off from pillars and from mined coal while in 

transit to the shaft bottom from the various operating sections (very low from 

the isolated panel), and from transfer of all coal to the skips, which were 

hoisted in a shaft that served as an intake airway. 

The frequent automatic stoppages of the continuous miner when mining in 

virgin coal (area 2), notwithstanding the acceptable methane concentration in 

the immediate return airway, show the need to develop methods for conducting 

a larger volume of air to the working face. 

Although considerable degasification was obtained in the isolated panel 

made such by development of main headings for haulage and ventilation in a new 

mine, further studies are required to determine the safety and costeffectiveness of mining butt headings in unisolated major panels, to develop a 

set of headings to isolate a major coal panel, and to develop four to five 

butt headings within the panel after 12 months of complete isolation. The 

objective is to obtain a body of pertinent data in predominantly mined, very 

gassy coalbeds that would permit any coal company to decide whether it would 

be practicable to undertake the isolation technique.