METHANE EMISSION RATE STUDIES 

IN A NORTHERN WEST VIRGINIA MINE 
METHANE EMISSION RATE STUDIES IN A NORTHERN WEST VIRGINIA MINE 

by 

Stephen Krickovic, Charles Findlay, and W. M. Merritts 

Bureau of Mines Methane Control Program 

Technical Progress Report - 28 

August 1970 

U. S . DEPARTMENT OF THE INTERIOR 
CONTENTS 

Page 

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

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

Acknowledgments ......................................................... 3 

Description of study area ............................................... 3 

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

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

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

Reconnaissance ..................................................... 5 

Location of instruments ............................................ 5 

Instrumentation .................................................... 6 

Results ................................................................. 6 

Conclusions ............................................................. 11 

ILLUSTRATIONS 

1 . Location of study area .............................................. 2 

2 . Location of faces and monitoring instruments and arrangement of 

ventilation and face haulage at start of study .................... 3 

3 . Air velocities in heading 1 showing location of average air 

velocity .......................................................... 4 

4 . Air velocities in heading 8 showing location of average air 

velocity .......................................................... 5 

5 . Sequence of mining . ................................................. 8 

6 . Methane emission rates and air volumes in the left air split on 

shift 3. April 14. 1969 ........................................... 9 

7 . Methane emission rates and air volumes in the left air split on 

shift 2. April 15. 1969 ........................................... 9 

8 . Methane emission rates and air volumes in the right air split 

on shift 2. April 17. 1969 ........................................ 10 

TABLE 

1 . Summary of results .................................................. 
METHANE EMISSION RATE STUDIES IN A NORTHERN WEST VIRGINIA MINE 

by 

Stephen Krickovic, Charles ~indla~,~ and W* M* Merritts 

ABSTRACT 

Methane emission rates were studied in a Pittsburgh coalbed mine in 

northern West Virginia. A fullface boring-type continuous miner, equipped 

with a methane monitor, was used in the development of a set of eight main 

headings, one side of which was near old workings; the other side abutted 

virgin coal. Two air splits ventilated the section. Air volumes and methane 

percentages were recorded, and time studies of the miner were made during five 

consecutive operating days, during which a complete cycle of mining the headings and one line of related breakthroughs was accomplished. 

Methane emission rates increased significantly as mining progressed from 

the side near old mine workings toward the virgin area, and generally 

increased with coal extract ion. 

I Mining in the heading immediately adjacent to virgin coal was interrupted 

quite frequently, owing to excessive methane concentrations at the face, 

despite adequate air volumes and acceptable methane concentrations in the 

immediate return airway. 

INTRODUCTION 

Methane is contained under pressure within the micropores, joints, and 

fractures of gassy coalbeds. Breaking down the coal from solid faces tends 

to steepen the pressure gradient in the coalbed and exposes considerable area 

in the mined coal and in the newly exposed solid coal surfacesY4 all of which 

increases the emission of methane. This condition is particularly severe with 

the fullface boring-type continuous miner because coal is usually mined in one 

=Research manager, Environmental Control Technology, Pittsburgh Mining 

Research Center, Bureau of Mines, Pittsburgh, Pa. 

2Mining engineer, Pittsburgh Mining Research Center, Bureau of Mines, 

Pittsburgh, Pa. 

3~ining engineer, Coal Mine Safety Subdistrict Office, District A, Bureau 

of Mines, Wilkes-Barre , Pa. 

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

%in. Cong. J., v. 53, July 1967, pp. 52-57. 
FIGURE 1. - L
.t[K "'"'7" SZOPDOg 0 .RII ".I? IF. . * lmtk 

Bet conveyor 

m 

C 

uIW ZW 

, , . reel 

FlGU RE 2. - Location of Faces and Monitoring Instruments and Arrangement of Ventilation 

and Face Haulage at Start of Study. 

b~ervik, Joseph. Behavior of Coal-Gas Reservoirs. BuMines Tech. Prog. Rept. 

10, April 1969, 10 pp. 

Deul, Maurice. Methane Drainage From Coalbeds: A Program of Applied Research. 

Proc. 60th Ann. Meeting of the Rocky Mountain Coal Min. Inst., Estes Park, 

Colo., June 28-July 1, 1964, pp. 54-60. 

Perkins, J. H., and Joseph Cervik. Sorption Investigations of Methane on 

Coal. BuMines Tech. Prog. Rept. 14, May 1969, 6 pp. 
instruments at the beginning of the study. A continuous boring-type fullface 

miner, equipped with a methane monitor located 5 feet back of the rotors, was 

used to drive the headings 14 feet wide (between semicircle ribs at center) 

and 7 feet high, with 6 to 10 inches of roof coal left in place for protection. 

Coal was discharged onto the floor for subsequent loading with a conventional 

loader into shuttle cars, which trammed the coal to a conveyor-belt loading 

station. 

As shown in figure 2, the four middle headings served as air intakes to 

the last complete line of breakthroughs where, by canvas stoppings and a check, 

air was confined into heading 5 for splitting into left and right air splits, 

both of which were regulated. 

During mining, the faces of the headings and breakthroughs were ventilated by a portable 10,000-cubic-foot-per-minute, free-flow capacity, auxiliary fan equipped with 16-inch-diameter reinforced tubing. The fan was 

relocated progressively for each working place, to prevent recirculation of 

air and interference with haulage; the end of tubing always was maintained as 

far ahead of the operator as practicable and safe. Upon completion of mining, 

the miner was trammed out of the place, line brattice was installed immediately to maintain ventilation, and the auxiliary fan was moved to the proper 

location for mining at the next working face. 

Rib 

Bottom 

Note: 

Cross-sectional area=88 sq ft 

Average air velocity = 359 ft /min 

FIGURE 3. - Air Velocities in Heading 1 Showing Location of Average Air Velocity(Circled). 
Rib 

Bottom I 

Note: 1 

Cross-sectional area- 88 sq f t 

Average air velocity = 331 ft/min 

FIGURE 4. - Air Velocities in Heading 8 Showing Location of Average Air Velocity (Circled). 

MONITORING 

Reconnaissance 

After the study area was selected, Bureau mining engineers examined the 

area with the company's representative to note details of the arrangement of 

temporary s toppings, line brattice , canvas checks, auxiliary fan, and haulage 

routes. 

Location of Instruments 

To simplify monitoring, the return air of each split was confined to one 

heading instead of the two normally used. Locations for instrumentation in 

these headings were selected to obtain reasonably uniform air velocities in 

the cross-sectional areas. A grid system of vertical and horizontal strings 

to form 1-foot squares was set up in each of the two headings. Air velocities 

were then measured with a handheld vane-type anemometer iq each square, and 

the square in which the air velocity most closely approached the average for 

the total cross-sectional area was determined. Figures 3 and 4 show the air 

velocities in the 1-foot squares and the average air velocity in headings 

1 and 8, respectively. I 
Instrumentation 

The sensing heads of the continuously recording methanometer and anemometer developed by the ~ureau' were installed in the average velocity square in 

each cross-sectional area in headings 1 and 8. Due to interference from haulage equipment, handheld anemometers and methanometers were used to measure air 

velocities and methane concentrations in the intake air heading just outby the 

point where the air was split. 

The methane monitoring team consisted of a mining engineer and an engineering aid on each shift. The engineer studied the continuous miner to 

record the operating and idle times, feet of mining advance, and production 

per shift, to secure data on all mining, ventilation, and haulage equlpzsnt, 

and to observe any unusual conditions relating to the study. 

The engineering aide was responsible for the adjustment and replacement 

of instruments and the changing of batteries as required. He also took periodic check measurements of the air velocities and the methane concentration 

near the "average squares" with handheld instruments to ascertain the accuracy 

of the recording instruments. These check measurements and the times taken 

were recorded on the respective instrument charts. 

RESULTS 

Figure 5 shows the sequence of cuts made with the continuous miner by 

dates and shift numbers. The first shift is 8 a.m. to 4 p.m., the second is 

4 p.m. to midnight, and the third is midnight to 8 a.m. 

Table 1 summarizes the results of the study. For example, the first 

table entry shows that on shift 3 (midnight to 8 a.m.) on April 14, 1969, the 

continuous miner extracted coal in the breakthrough between headings 2 and 1 

and in heading 1, worked 120 minutes and was idle 360 minutes, advanced 74 

feet, and produced 258 tons of coal. Sixty-eight cubic feet of methane per 

minute flowed into the left split of air (35,600 cfm), resulting in a methane 

concentration of 0.19 percent; 112 cubic feet of methane per minute flowed 

into the right split of air (28,700 cfm), resulting in a methane concentration 

of 0.40 percent; the total methane flowing into the section inby the instruments was 180 cubic feet per minute, resulting in 0.28 percent concentration 

of methane in 64,300 cubic feet of air per minute flowing through the section. 

During the 13 operating shifts, the continuous miner was operated 46 percent of the available time, advanced an average of 98 feet per shift, and 

produced an average of 339 tons of coal per shift. 

GLaScola, J. C., and Joseph Cervik. Development of Recording Methanometers 

and Recording Anemometers for Use in Underground Coal Mines. BuMines Tech. 

Prog. Rept. 15, May 1969, pp. 9-14. 
TABLE 1. - Summary of results 

Date 

(1969) 

Apr. 14. .... 

Apr. 15... .. 

Apr. 16..... 

Apr. 17... .. 

~pr. la... .. 

Shift 

No. 

3 

1 

2 

3 

1 

2 

3 

1 

2 

3 

1 

2 

3 

1 

2 

Working face 

2-1,l 

1,2 

2,3,4 

4 

4,5 

5-4,5-6 

- 

- 

5-4,5-6,6-7 

6-7,7-8 

7-8,8 

8 

7,6 

6,4-3 

3-2,2-1,4-3 

Face 

advance, 

ft 

74 

142 

133 

50 

120 

83 

- 

- 

118 

42 

63 

70 

135 

80 

158 

Average ......................... 98 

Minutes 

Working 

120 

226 

180 

120 

153 

175 

- 

- 

130 

225 

240 

210 

165 

245 

240 

Coa 1 

production, 

tons 

258 

49 4 

46 3 

174 

418 

2 89 

- 

- 

410 

146 

219 

244 

47 0 

27 8 

550 

Idle 

360 

254 

300 

360 

327 

305 

- 

- 

350 

255 

240 

270 

315 

235 

240 

187 3 39 293 

split 

Air, 

cfm 

35,600 

35,600 

34,000 

32,700 

7732,200 

32,000 

32,200 

32,200 

7432,000 

32,000 

29,500 

6327,300 

27,400 

32,000 

33,400 

Left 

32,000 

Methane 

Percent 

0.19 

.23 

.24 

.23 

.24 

.28 

.23 

.23 

.23 

.23 

.24 

.23 

.23 

.20 

.30 

.24 

s3lit 

Air, 

cfm 

28,700 

28,700 

28,300 

27,800 

28,000 

31,300 

31,300 

30,000 

29,500 

32,200 

13032,000 

32,200 

Cfm 

68 

81 

81 

75 

88 

74 

74 

74 

71 

63 

63 

100 

1 75 

Right 

29,900 

Methane 

Percent 

0.40 

.41 

.40 

.40 

.40 

.37 

.37 

.43 

.51 

.42 

.40 

.40 

.41 

Cfm 

112 

117 

113 

114 

.3910727,500 

111 

114 

114 

.4012030,000 

130 

151 

.5216131,000 

137 

129 

124 

M

P

c

0
FIGURE 5. - Sequence of Mining. 

The effect of the proximity of old workings on methane emission rate is 

clearly shown by the fact that during the two idle shifts on April 16, 74 cubic 

feet per minute flowed into the left split of air, while 114 cubic feet per 

minute flowed into the right split. This is further substantiated by the fact 

that during the study period, 541,000 cubic feet of methane flowed into the 

left air split during the production of 2,646 tons of coal, while 893,000 

cubic feet of methane flowed into the right split during the production of 

1,767 tons of coal. Thus, the methane emission rate was 204 cubic feet per 

ton of coal mined in the left split compared with 505 cubic feet per ton of 

coal mined in the right split. 

The effect of coal production on methane emission rate could not clearly 

be shown. While periods of high coal production were generally accompanied 

by increased gas emissions, the fact that different amounts of coal were not 

mined under similar circumstances precluded a clear assessment of this factor. 
FIGURE 6. - Methane Emission Rates and Air Voiumes in the Left Air Split on Shiii 3, 

April 14, 1969. 

t IIIIII 

----------__________ - Methane emission - 

d In cD -0 o Q d N 

= 3 

93 

80- 

64 

llllllllllllllllllllllllllllli~~l~~~

I0p.m. I l p.m. Midnight 

TI ME 

Midnight 4 a.m. 5 a.m. 6 a.m. -a.m. 

TIME 

E rr) 

Z90L' 'I I" " I I1 

; e0 ---- ---------------------- -N Methane emission 

g 64-a, 

ro 

0, 

m 

E - \Air-split volume -31 -1 

r 0 

W llll,111,,1 ,IIIII,Il IIII lIII11I > 

7p.m. 8p.m. 9 p.m. I0p.m. Iz 

- 

FIGURE 7. - Methane Emission Rates and Air Volumes in the Left Air Split on Shift 2, 

April 15, 1969. 

W 

5 

1 3 

y36 9: 

-35 kn 

-3420 

Y' 

[L 

a 

cD t- 03 r'Q Q cD a OD ot- 

- 

- Air -split volume 

- KEY - Work time 

---- Idle time 

11111111111 11111111~11 11,I I, IIIII 

ago 

I- 74- 

W 

I 

Table 1 shows weighted average methane emissions over an 8-hour shift. 

Figures 6, 7, and 8 show fluctuations in methane emission during a shift as a 

function of production. 

- 

Figure 6 shows the methane emitted during the third shift on April 14. 

Mining was in the breakthrough between headings 1 and 2 and in heading 1. 

Although the weighted shift average was 68 cubic feet per minute, periods of 

coal extraction were accompanied by sharp increases in methane emission 

11 Ill I I 

- 

lllll~llll~~llrll~llllllllll~~lllll

87-------------- -------- - ---------- 

7M;thane emission 

- 

\Air-split volume KEY 

- 

lllllllllll Illllllllll 

-1 

a 

-T 

E 

-33 a 

32 

Work time - ---- - Idle time 

IIIIII 

-----------~ --___ '~efhone ---r1,y E 8 8 cv a, 

- 'Air-split volume - 

31 

=33 

32 

31 
W Ill[lI[lll[ 11111111111 I111111 

174- 

I6 I :-]-..-/\ /' .---- 1- -----/ 

52 \ \ 1 I\\ \\ \ I"] \Methclne emssion KEY 0 

> 

140>m Nrnernm o 00 -* 

.t,n W"'91"'D gk 2 

- Work time 

- 

- 

--- ------ Idle t~me (due to gas) -1 

a 

m 

Air-split volume 32 

30 

174 

161 

152 

E 140- '4- 

0 

i 

0 - 

m 

5' 

z 

W 

Midnight 

FIGURE 8. - Methane Emission Rates and Air Volumes in the Right Air Split on Shift 2, 

April 17, 1969. 

W M 

5 4 p.m. 5 p.m. 6 p.m. 

0 7p.m. - I 

t- h W 

I~1IrIIIII1 )IIlIIIIIlI1 lllllllllll - 

- 

' --------------------- ---- - a 

followed by less sharply declining emission rates following cessation of 

extraction. 

Figure 7 shows the fluctuation in methane emission with production while 

mining in the breakthroughs between headings 4 and 5 and between headings 5 

and 6 on the second shift, April 15. As in figure 6, increased methane emission accompanied coal production. 

32 

3 1 

30 

E 

'4- 

0 

Methane emission - - 

- ! 

Air-spl i t volume - 

Figure 8 shows methane fluctuations during mining in heading 8 on the 

second shift, April 17. This heading abuts virgin coal, and it was anticipated that maximum methane emissions would be encountered in this heading. 

The methane emitted during the shift ranged from 152 (0.50 percent) to 

174 cubic feet per minute (0.56 percent). The methane emission rate was 

responsive to mining, increasing rapidly during mining and decreasing only 

slightly less rapidly immediately following the cessation of mining. Usually 

after mining had progressed for less than 10 minutes, the concentration of 

methane at the face exceeded safe limits and caused the methane monitor 

mounted on the continuous miner to cut off the power so that mining ceased. 

Power was restored and mining resumed after the concentration of methane 

reached a safe level. Thus, coal was mined for only 20 percent of that shift, 

and three-fourths of the idle time was caused by excessive methane concentrations at the face. 

Illllllllll Illllllllll Illlllllll 1 
While figures 6, 7, and 8 are generally similar, the amount of methane 

produced during idle periods and during production periods increased as mining 

progressed from the left headings near old workings to the right headings near 

virgin coal. 

CONCLUSIONS 

While all the causes of variations in methane emission rates are not 

known, some general conclusions may be drawn from this study: 

1. The rate at which methane flowed into the section ranged from 180 to 

229 cubic feet per minute and averaged 199 cubic feet per minute over the 

study period. 

2. Analyses of average emission rates during periods of production and 

periods of idleness showed that coal production caused a maximum increase in 

methane emission of 54 cubic feet per minute. 

3. The effect of mining adjacent to virgin coal compared with mining 

adjacent to old workings (heading 8 versus headings 1 and 2) is evident when 

244 tons of coal produced in heading 8 during shift 17-2 resulted in the 

emission of 32 cubic feet per minute of methane more than when 494 tons of 

coal was produced in headings 1 and 2 during shift 14-1; total mining time 

during both shifts was approximately the same. 

4. The fact that the methane monitor, mounted 5 feet outby the cutters 

on the continuous miner, frequently sensed excessively high methane concentrations, while the air split of 31,000 cubic feet per minute at the monitoring 

station contained only 161 cubic feet of methane per minute (0.52 percent), 

shows the difficulty of ventilating a boring-type continuous miner to control 

methane . 

5. This study shows that it is possible to predict the magnitude of the 

methane problem that might be encountered during future development and that 

some qualitative inferences can be made as to the effect of time on the lessening of methane emission rates.