Historical Development of technologies for Controlling Methane 

in underground Coal Mines 

Charles D. taylor 

NIOSH, Pittsburgh, Pennsylvania, United States 

C. Özgen karacan 

NIOSH, Pittsburgh, Pennsylvania, United States 

aBStraCt: For 100 years, a major emphasis has been placed on controlling methane in underground coal 

mines in order to improve worker health and safety. This emphasis and related research, as well as legislative 

actions, have led to new mining equipment and methods which have changed methane control practices in coal 

mines. The U.S. Bureau of Mines (USBM), and more recently the National Institute for Occupational Safety 

and Health (NIOSH), have been an integral part of many of these developments which have improved mining 

health and safety, either by initiating research programs or by collaborating with the U.S. mining industry. Two 

primary goals of this research have been to reduce underground methane explosions by controlling methane 

emissions from the coal bed and the gob, and diluting methane gas that has been liberated in the face areas. The 

decreased number of fatalities due to methane explosions clearly shows the success of this program. This paper 

discusses several milestone events that show the progress of this methane control research. 

introDuCtion 

Most explosions in coal mines occur when an 

explosive methane-air mixture is present. Since its 

inception in 1910, the U.S. Bureau of Mines and the 

National Institute for Occupational Safety and Health 

have conducted research to help prevent methane 

explosions. Some of this methane research has been 

in direct response to underground explosions. Other 

research has been the result of applying new technologies to reduce the likelihood of underground explosions (for example, degasification with directional 

drilling). This paper examines several of the major 

technologies that the USBM and NIOSH developed 

for controlling methane in underground coal mines. 

The technologies are grouped and discussed according to the decade(s) of their development. 

BaCkGrounD 

In 1907, following the explosions in four mines 

that killed over 600 miners, the United States coal 

mining industry gained an international reputation as “...being the most backward of the civilized 

nations” and was characterized as “...callous where 

financial interests have weighed against human 

lives.”(Colliery Guardian 1908). Responding to 

the large loss of life in the mines, the United States 

public demanded that safety in U.S. coal mines be 

improved. In 1910, the existing U.S. Geological 

Survey department was used to form the basis for the 

U.S. Bureau of Mines. 

CHronoLoGiCaL DEvELoPMEnt of 

MEtHanE ControL tECHnoLoGiES 

1910 to 1950 

In the early 1900s, it was a common belief that most 

mine explosions were the result of unsafe practices 

that occurred throughout the mines. Early USBM 

research, therefore, emphasized education of the 

mining industry. It was assumed that a more educated mining community would act in a way that 

would result in safer mines. 

In 1910, the Bureau of Mines opened an experimental mine in Bruceton, PA. From 1914 to 1925, 

the Bureau focused almost exclusively on the causes 

of explosions and ways to prevent them. Explosion 

demonstrations conducted at Bruceton for the public did not explain why methane ignitions occurred, 

but graphically showed the effects of igniting dust or 

methane gas in a coal mine (Figure 1). 

Early Ventilation Studies 

Only limited ventilation research was conducted in 

the early 1900s because there was a common belief 

that explosive methane-air mixtures would accumulate in face areas regardless of the quantity of air 

provided by the ventilation system. The emphasis 

of the research was on removing sources of methane 

ignitions, such as explosives and open flame lights, 

rather than improving ventilation. 

The quantities of air normally provided in 

mines were considered adequate (Harrington and 

Denny 1938). As long as coal was loaded by hand, 

relatively small amounts of fresh air were needed to 
dilute the quantities of methane released at the face. 

Health requirements of the workers and animals, not 

methane control, usually determined the amount of 

air provided to the working places (Miller 1940) 

(Figure 2). In the 1930s and 1940s, airflow quantities 

increased as more mines began to use mechanical 

fans for ventilation. 

figure 1. Early explosion test at the u.S. 

Bureau of Mines 

figure 2. Mining conditions at a work place 

Ignition Sources 

Permissible Explosives. The USBM played 

an important role in the development and testing 

of permissible explosives which, when used properly, would not ignite methane. As mines began to 

use permissible explosives, the number of ignitions 

decreased; however, at some mines with less gassy 

seams, people continued to think permissible explosives were not necessary. Opposition to use of the 

permissible explosives also came from miners who 

said they were too expensive and broke coal into 

pieces that were too small. That is, the miners who 

were paid for lump coal saw their incomes decrease 

when they used permissible explosives. 

Open Flame Lights. Use of open flames for 

underground illumination was known to be hazardous, but there were few alternatives until the Bureau 

helped to develop the electric cap lamp (also known 

as a “closed light”). The Bureau issued the first permit for an electric light in 1914 (Fieldner 1950), 

but the use of open flame lights continued in many 

less gassy mines where they were considered safe. 

Initially, mines were not required to use the electric 

lights. Mines were often identified as either “open 

light” or “closed light” depending on whether they 

were considered non-gassy or gassy, respectively. 

Some miners preferred open lights because they 

provided more light than early electric lights, and the 

electric lights had heavy batteries that often leaked 

electrolyte (Figure 3). 

figure 3. thomas Edison with early electric 

cap lamp 

Some workers opposed the 

use of electric cap lamps because they believed ventilation would be neglected in mines that used electric lights. There were reports that some companies 

tried to force workers to mine in gassy areas of the 

mine while wearing the electric lights. 

Early Coal Bed and Gob Degasification Studies 

The potential benefits of using boreholes to drain gas 

from coal in advance of mining were recognized in 

the early 1900s, especially when mining deeper and 
more gassy seams (Diamond 1994). However, the 

quantities of methane removed by drilling short horizontal holes in the mine ribs were small (Lawall and 

Morris 1934). From the early 1930s until 1950, some 

mines tried methane drainage technologies developed in Europe, with some success. Two methods 

used were drilling holes in broken sandstone above 

gassy coal seams (Coal Age 1938), and using crossmeasure boreholes to drain the gas and move it to 

surface (Diamond 1994). 

1950 to 1969 

In the 1950s and 1960s, the introduction of new mining equipment and mining methods had a big effect 

on how ventilation was used to control methane 

concentrations. 

Continuous Mining Machines 

One USBM researcher noted that the continuous 

mining machine (Figure 4) revolutionized coal mining (Stahl 1958). 

figure 4. Early continuous mining machine 

Methane liberation rates during 

continuous mining were much higher than during 

conventional mining, due to the faster coal extraction 

rates. Methane concentrations during continuous 

mining sometimes exceeded 5% (the lower explosive limit for methane gas) at distances as far as 20 

feet from the face (Stahl 1958). Ventilation practices 

available at that time were inadequate for controlling 

methane during continuous mining. 

Face Airflow Control 

Although the increased use of mechanical fans 

resulted in more airflow underground, much of the 

air was lost before it could reach the working faces 

due to leakage through doors and curtains. Tests 

examined ways to improve delivery of air to the face. 

•		 Curtains— Most curtains were made of jute 

fabric. Air leakage increased with increasing 

porosity. Less porous materials, such as plastics, along with better installation techniques 

that allowed less leakage between the curtain 

and roof were recommended (Dalzell 1966). 

•		 Tubing— When permissible auxiliary fans 

became available for underground use, studies examined factors affecting the delivery of 

air to the face using fans with attached tubing. 

Tubing materials and construction techniques 

were tested to determine how airflow shock 

losses could be reduced and airflow quantities 

increased (Peluso 1968). 

•		 Blowing versus exhausting ventilation— 

Studies using comparable blowing and exhausting face ventilation systems with curtains measured methane levels near the mining face for a 

range of operating conditions. The blowing systems were on average more than 5 times more 

effective for diluting methane in the face area 

(Luxner 1969). 

Methane Monitors 

Until the 1950s, the flame safety lamp (Figure 5) 

was the primary means used for detecting methane 

in mines (Ilsley 1933). 

figure 5. Miner with safety lamp 

The effectiveness of the ventilation system was determined more by observing 

operating conditions than by measuring gas levels. 

In 1958, the Bureau of Mines initiated programs to 

develop a methane detector system that would provide continuous monitoring of methane at the mining 

face (James 1959). 

Eventually all mining machines had to be 

equipped with these machine-mounted methane 

monitors [(30 CFR § 75.342(a)(1)]. Data from these 

monitors became the basis for evaluating ventilation 
effectiveness for methane control and compliance 

with methane standards. 

Improved Methane Drainage 

•		 Hydraulic stimulation— The efficiency of vertical degasification wells was improved by using 

hydraulic stimulation (Spindler and Poundstone 

1960). In one coalbed, there was more than a 

16-fold increase in gas production. In another 

study, the methane content in the main return 

air currents after stimulation was reduced more 

than 86% (Diamond 1994; Merritts et al. 1963). 

•		 Methane drainage on longwall panels—Use of 

vertical boreholes reduced methane concentrations in the returns while decreasing the level of 

ventilation required for methane control (Elder 

1969). 

1970 to 1980 

1969 Coal Mine Health and Safety Act 

The Federal Coal Mine Health and Safety Act of 

1969 set standards for methane and dust control. 

Several research projects in the 1970s examined 

ways to improve ventilation and reduce airborne dust 

levels to the new required levels. Most of the studies concluded that exhaust ventilation was needed 

for adequate dust control (Kingery 1969; Mundell 

1977). Earlier work had shown that blowing ventilation was better for methane control (Luxner 1969) 

(Figure 6), and some mines wanted to continue using 

blowing ventilation systems. 

figure 6. Data comparing blowing and 

exhausting face ventilation 

These mines began 

cooperative studies with the Bureau to develop a 

machine-mounted dust scrubber (Tomb 1973). The 

flooded bed machine-mounted scrubber was shown 

to lower dust levels when using blowing ventilation. 

Initially, there were concerns that scrubber recirculation would cause methane levels to increase, but tests 

showed that concentrations did not increase as long 

as the scrubber exhaust did not reduce intake air flow 

to the face. 

Developments in Coal Bed Methane Drainage 

In the 1970s, studies examined techniques for removing methane from longwall gob areas. 

•		 Use of an exhauster with a slotted vertical pipe 

allowed faster mining rates and lower ventilation airflow in the mine (Moore and Zabetakis 

1972). 

•		 Isolating panels during degasification improved 

gas removal by 70% (Findlay et al. 1973). 

•		 The best levels for bit thrust and rotational speed 

for rotary drilling of holes were investigated 

to find the optimum combination to stay in 

the coalbed and drill ahead of coal production 

(Cervik et al. 1975). 

•		 Horizontal boreholes drilled from the bottom of 

the shaft in virgin coal reduced methane emissions at the working face by 50% (Diamond, 

1994). 

•		 Hydraulic stimulation had only minimal effects 

on improving degasification of a longwall 

panel (Maksimovic et al. 1977), but boreholes 

stimulated with foam and proppant sands significantly reduced methane emissions (Steidle 

1978). The stimulation treatment did not cause 

damage to roof or floor. 

•		 Water infusion techniques developed by the 

Bureau of Mines were used to move gas away 

from face areas and into the return airways. Use 

of this technique reduced gas emissions in the 

more permeable coal seams by almost 90% 

(Cervik 1977). 
1980 to 1990 

By 1980, the Bureau of Mines had demonstrated 

effective face ventilation techniques for controlling 

both methane and respirable dust on continuous mining operations. Maximum curtain or tubing setback 

distances were usually 10 ft for exhausting and 20 ft 

for blowing ventilation systems. Most mining cuts 

were 20 ft deep and the machine operator sat at the 

rear of the machine. In the 1980s more machines 

were equipped for remote control operation. 

Remote Control 

As more mining machines were equipped with 

remote controls to remove the operator from the 

immediate face area, cutting depths in the 1980s 

increased to 35 ft and greater. Studies examined 

whether available face ventilation practices were 

adequate for controlling methane levels during deep 

cut mining (cut depths greater than 20 ft). 

•		 The benefits of using directional water sprays 

for improving face airflow (spray fan system) had been demonstrated earlier by Kissell 

(1979). With exhausting ventilation and a modified spray fan system, cutting depths could be 

increased to 40 ft with no significant increases 

in methane levels (Ruggieri 1987). 

•		 When using a machine-mounted scrubber with 

blowing ventilation, cutting depths to 50 ft 

could be attained without increasing methane 

levels (Volkwein 1986). 

Most mines employing deep cut mining used scrubbers with blowing ventilation or a spray fan system 

with exhausting ventilation. 

Longwall Methane Control 

Longwall mining does not require curtain or tubing 

to ventilate the face. However, airflow must be maintained along the entire face for good methane control 

(Cecala 1986). Studies showed that: 

•		 The highest methane levels were measured 

during cutting at the headgate. Placement of 

a curtain at the headgate diverted needed air 

flow away from the gob and down the panline 

(Cecala 1986). 

•		 A modified water spray system on the shearer 

(shearer clearer) improved air flow over the 

mining machine by reducing eddy zones where 

methane could accumulate (Cecala 1986). 

Frictional Ignition Suppression 

Past research had eliminated most ignition sources 

from coal mines, but the number of ignitions at the 

mining face increased following the introduction of 

continuous mining machines. These frictional ignitions occurred when the metal machine bit in the 

rotating cutting drum became hot enough, usually 

during cutting in sandstone rock, to deposit a streak 

of hot metal on the rock surface. When the hot metal 

contacted a flammable methane-air mixture, an ignition could occur (Courtney 1990). 

Laboratory tests designed to simulate cutting in 

hard rock (Figure 7) showed that frictional ignitions 

could be reduced by changing bits more frequently 

and/or using bits with larger carbide inserts to reduce 

contact between the steel bit shank and the rock. 

figure 7. Methane frictional ignition test 

Ignitions could also be reduced by cooling the rock 

surface with water directed from a nozzle mounted 

directly behind the bit (Courtney 1990). 

Coal Seam Methane Drainage Research 

•		 The Bureau of Mines developed a “direct 

method” for determining coal bed gas content 

(Diamond and Levine 1981) to make preliminary estimates of ventilation requirements and 

to determine if methane drainage would be beneficial (Diamond et al. 1986). 

•		 A comprehensive report (Diamond 1982) 

detailed geological factors important during the 

drilling of degasification boreholes in order to 

achieve optimum methane control was written. 

Techniques for drilling boreholes from the surface to intercept coal beds were demonstrated 

(Oyler and Diamond 1982). 

•		 Progress was made on developing numerical models for methane control in coal mines 

(Schwerer et al. 1984). The two-dimensional 

mathematical model and accompanying numerical model were used to predict methane influx 

into the coal mines under a variety of mining 

conditions. 
1990 to 2000 

In 1996 certain research programs of the Bureau of 

Mines were transferred to NIOSH. The emphasis of 

most research during this decade was on improving 

the effectiveness of available ventilation techniques 

and providing data needed by the mining industry 

for better implementation of existing technologies. 

A ventilation test gallery (Figure 8) was specially 

designed to evaluate factors affecting face ventilation and methane monitoring techniques. 

figure 8. nioSH ventilation gallery 

Airflow Patterns and Methane Distributions 

Earlier Bureau tests showed that mapping airflow 

patterns and methane concentration near the face 

helped during the design of face ventilation systems 

(Luxner 1969). A surface test facility was used to further study airflow patterns and methane distributions 

in the area between the ventilation curtain or tubing 

and the face. Study results showed that: 

•		 The narrower the entry, the more likely flow to 

the face will be disrupted and methane levels 

will increase (Taylor 2005). 

•		 Operation of machine-mounted water sprays 

and scrubber can increase face airflow by a factor of 5 (Thimons 1999). 

•		 A spray fan system that uses water sprays 

directed toward the return air side of the face 

reduced methane levels by increasing airflow 

across the face. If the water sprays are directed 

straight toward the face methane levels are also 

reduced but concentrations can increase in some 

areas near the face, especially if intake airflows 

are low (Taylor 1997; Chilton 2006). 

instrument location on continuous mining 

machines. In the ventilation gallery, methane measurements made at the face and at multiple locations 

on the machine were compared. Researchers determined that methane concentrations should be measured on the return side of the mining machine, and 

that if alternative methane sampling locations further 

from the face are selected, action levels should be 

reduced to assure protection to worker is not diminished (Taylor 2001). 

instrument location on a roof bolting machine.

Based on results from tests conducted in the ventilation gallery, Taylor (1999) proposed an alternative 

procedure for methane monitoring during roof bolting of deep cuts. The procedure calls for methane to 

be monitored continuously using a bolter mounted 

methane monitor, while a hand held detector with 

extendable probe is used to periodically “sweep” 

the area 16 feet inby the last permanent row of roof 

supports. 

Methane Control Research 

Studies concluded that: 

•		 About 90% of the gas from longwall gobs 

comes from the overlying coalbeds (Diamond 

et al. 1992). 

•		 On longwall panels, 77% more gas came from 

holes drilled at the end of the panels and at 

panel margins where strata were in tension 

compared to holes drilled in the center of the 

panel. Drilling gob vent holes in panel margins has become standard practice in most U.S. 

mines (Diamond et al. 1994). 

•		 Methane emission rates increase as the length 

of the longwall face increases, but not necessarily in the same proportion (Diamond and Garcia 

1999). 

2000 to 2010 

Emphasis was placed on improving the evaluation 

and use of methane monitors. Ultrasonic anemometers were used to plot airflow in face areas in order 

to evaluate factors affecting methane control at the 

face. Computer modeling was used to study the flow 

of methane gas through rock strata and after its liberation at the mine face 

Methanometer Response Time 

Methane concentration rise and fall quickly during mining. In order for instruments to read accurately they must response quickly to these changes. 

Researchers developed test procedures and equipment for measuring methanometer response times. 

Using the new procedures it determined that the 

design of the dust caps used to protect the sensor 

heads was the major factor affecting response times. 

Response data was presented for both machinemounted monitors (Taylor 2004) and hand held 

detectors (Chilton 2005). Tests compared methane 

response times of instruments using infrared and heat 

of combustion sensors. Again, dust cap design was 
the biggest factor affecting differences in response 

times. In the ventilation gallery where face airflow 

conditions were simulated, it was shown that when 

exposed to the same gas concentrations instruments 

with faster response times showed larger peaks and 

dips in concentration (Taylor 2008). 

Methane Measurements Distant from the 

Working Face 

Although regular methane monitoring is required 

near working faces, much less methane sampling 

occurs in areas distant from the face. Small person wearable methane monitors were evaluated. 

Equipped with aural, visual and vibratory alarms, the 

instruments provided alarms to warn workers when 

methane levels exceed preset limits (Chilton 2005). 

Measuring Airflow Speed and Direction 

Researchers developed techniques for using ultrasonic anemometers to measure airflow direction and 

speed in the ventilation gallery (Taylor 2005). The 

anemometers were used to measure air flow direction 

and speed inby the ventilation curtain. Flow profiles 

drawn for different size empty entries showed that 

less air reaches the face when the entry is narrower. 

The same type of flow pattern can occur at the face 

when machine-mounted water sprays or scrubbers 

are not used. Data obtained using the anemometers 

showed an increases in face airflow when the scrubber was used (Taylor 2006). 

Development of Computer Models for Face Airflow 

and Methane Distribution 

Airflow and methane data obtained in the ventilation 

gallery was compared to data generated by a computer simulation model. The flow and the methane 

concentration data from the model were in good 

agreement with the empirical results. 

Methane Control and Degasification Research 

Besides the field work and observations, a special 

emphasis was placed on integrating analytical and 

numerical reservoir simulation techniques. Research 

in this area, based on the mining industry’s need to 

respond to changing mining conditions and economic drivers, produced several outputs and recommendations. Study results showed that: 

•		 The methane emission increase due to a face 

width increase can be controlled by increasing 

ventilation quantities and reducing shearer transit times (Schatzel et al. 2006; Krog et al. 2006), 

increasing the number of gob gas ventholes, and 

drilling boreholes on the headgate side close to 

the start up of the panel. These holes should be 

operated continuously (Karacan et al. 2005). 

•		 Horizontal in-seam degasification boreholes 

can be effectively used for methane drainage 

of the coal bed prior to the start of longwall 

mining. The patterns of the boreholes can be 

optimized by using numerical reservoir simulations. In general, boreholes drilled perpendicular to face cleats produce more methane per 

borehole length and more effectively degasify 

the coal bed. Extension of methane drainage 

duration prior to mining start is also an effective 

way of decreasing methane emissions during 

mining. When this is not possible, the boreholes 

should continue producing until the mining face 

reaches their location (Karacan et al. 2007a). 

•		 Entry development processes can be modeled 

by reservoir simulations. Methane emissions 

into the entries during their development can 

be controlled by using shielding boreholes 

drilled parallel to the entries. These boreholes 

can serve both degasification and shielding purposes (Karacan et al. 2007a; Karacan 2007b). 

•		 Methane emissions during continuous miner 

operation are a function of mining parameters 

(Karacan 2007b) and coal bed reservoir parameters (Karacan 2008a). Optimum methane control strategies can be developed based on these 

two considerations. 

•		 Geological and structural characteristics of 

the coal bed are important to decide where to 

drill the boreholes (Karacan et al. 2008) and 

how they can affect the borehole productivity 

(Karacan and Goodman 2008). 

•		 Expert systems can be used in determining 

and optimizing longwall emissions (Karacan 

2008b), degasification system selection 

(Karacan 2009a) and forecasting the performance of gob gas ventholes (Karacan 2009b). 

•		 Longwall mining changes the hydraulic conductivity of the overlying strata. Hydraulic conductivity of the fractured zone affects the control 

of methane using gob gas ventholes. Hydraulic 

conductivities can be determined using slug 

testing methods (Karacan and Goodman 2009). 

It was determined that the hydraulic conductivities of gob gas ventholes vary based on the 

overburden thickness, the rate of the longwall 

face advance, and their locations over the panel 

(Karacan and Goodman 2009). 

SuMMary anD ConCLuSionS 

Research programs to prevent methane ignitions 

began with the establishment of the U.S. Bureau of 

Mines and remain an important part of the current 

NIOSH mining research program. The substantial 
reduction in the number of injuries and deaths due to 

mine explosions is probably the best indicator of the 

program’s success. Although the potential for explosions resulting from methane in mines still exists 

today, with knowledge gained from Bureau and 

NIOSH research it is now possible to work underground much more safely than previously. Research 

into better ways to utilize ventilation for the control of methane gas by underground ventilation and 

extraction prior to mining continues. 

References provided with this paper give more 

information about past Bureau of Mines/NIOSH 

methane control research. Additional sources of 

information include: 

•		 “Handbook for Methane Control in Mining” 

(Kissell 2006). 

•		 “Guidelines for the Prediction and Control of 

Methane Emissions on Longwalls” (Schatzel et 

al. 2008). 

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drilling holes in coal beds for degasification. 

Bureau of Mines RI 8097. 

Cervik, J., et al. 1977. Water infusion of coal beds 

for methane and dust control. U.S. Bureau of 

Mines RI 8241. 

Chilton, J. E., et al. 2005. Evaluation of person wearable methane monitors. Intl. Conf. of Safety in 

Mines Res Inst., Brisbane, Australia. 

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airflow movement and methane dilution at the 

working face. 11th US/North American Mine 

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bituminous coal mines, performance characteristics of common jute line brattice. Bureau of 

Mines RI 6725. 

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determination of the gas content of coal: procedures and results. Bureau of Mines RI 8515. 

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Bureau of Mines IC 8898. 

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determination of the gas content of U.S. coal 

beds. Bureau of Mines IC 9067. 

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of longwall gob gas: Lower Kittanning coal 

bed, Cambria County, PA. Bureau of Mines RI 

9430. 

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prediction of longwall methane emissions: a 

case study in the Pocahontas No. 3 coal bed, 

VA. NIOSH RI 9649. 

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Mines TPR 13. 

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research and problems yet to be solved. Bureau 

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Bureau of Mines RI 7790. 

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methane emissions and performance of gob 

gas ventholes. International Coalbed Methane 

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2007a. Numerical analysis of the influence of 

in-seam horizontal methane drainage boreholes 

on longwall face emission rates. International 

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importance of coal bed reservoir parameters for 

prediction of methane inflow rates during mining of longwall development entries. Computers 

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Karacan, C.Ö. 2008b. Modeling and prediction of 

ventilation methane emissions of U.S. longwall 

mines using supervised artificial neural networks. International Journal of Coal Geology 

73:371. 

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bed discontinuity effects on the production 

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numerical evaluation on the effects of impermeable faults on degasification efficiency and 

methane emissions during underground coal 

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of a surface borehole for gob degasification. 

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(degasification) from the Pocahontas No. 4 coal 

bed in southern West Virginia. Bureau of Mines 

RI 6326. 

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RI 7657. 

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RI 8640. 

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