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PRICE 25 CENTS
Sold only by the Superintendent of Documents, U. S. Government Printing Office

Washington, D. C.

UNITED STATES
GOVERNMENT PRINTING OFFICE

WASHINGTON

1928

PREFACE

This handbook, Safety in Coal Mining, has been prepared at my request by the chairman of the mine safety board of the Bureau of Mines. The purpose of the handbook is to make available in convenient form a concise statement of practices and methods recommended by the bureau for the increase of safety in coal mining.

Rapid growth in the use of machinery for cutting and loading coal, longer haulage ways, and the wider use of mechanical haulage have contributed toward economy in mining by making possible a larger output of coal without a corresponding increase in the number of workers. At the same time this mechanicalization of the mines has been accompanied by increased hazards from falls of roof and coal and from accidents in transporting the coal from the face to the tipple. Incidentally, also, the machines have introduced new hazards peculiar to themselves, although these hazards can not be classed among the major causes of mine accidents.

Progress in accident prevention is indicated by either a larger output per accident or fewer accidents per employee; double progress is realized when increased production per accident accompanies a reduction in the accident rate per employee.

It is hoped that this publication will prove helpful to safety engineers, mine owners, mine employees, and others in their endeavor to obtain the Nation's necessary fuel at a minimum cost in life and limb. The bureau plans to revise the handbook from time to time as developments in the industry, and further study and research, seem to warrant.

Scott TURNER, Director.

I

CONTENTS

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Preface------------------------

Introduction----

Acknowledgments-------

Accidents in coal mines, by causes-------

Comparison of accident rates in mines---

Accident rates of mining and of surface industries-----

Chief causes of coal-mine accidents

Organization, administration, and regulation.--

Explosions of gas or coal dust-

Methods of preventing mine explosions-

Ventilation

Constituents of mine air---------

Humidity -------------------------

Need of ventilation---

Coal-mine gases classified by origin-----

Physiological effects of mine gases--------

Testing the quality of mine air--

Approved instrument and apparatus for determining prin-

cipal mine gases_---

Detailed description of principal methods and instruments

for testing the presence and determining the proportions

of gases in mine air.

Sampling and analysis-------

Analytical apparatus_-----

Analysis of hydrocarbon gases by fractional distillation at

low temperatures and pressures---

Effect of inert gases on inflammability limits.

Amount of air required to ventilate a coal mine_-------

Gassy or nongassy mines---------

-----------------

Classification of coal mines by gas content-----

Notes on classification of mines by gas content_-.

Measuring the volume of mine air--

Methods of ventilating coal mines.---------

Arrangements for ventilation in shafts, slopes, or drifts-

Ventilating shafts or compartments------

Arrangements for ventilation at slope and drift mines.

Fans------

Underground fans-----

Electrically driven booster and auxiliary fans_

Coursing the air current in a coal mine_------

Layout of ventilation system.-----------

Main entries or slopes------

Branch entries or levels in pitching beds---

Longwall ventilation --

Overcasts, doors, regulators, and stoppings---

Sealing old workings----

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Explosions of gas or coal dust-Continued.

Explosibility of coal dust..

Relative explosibility of coal dusts_----

Rock-dusting as a preventive of coal-dust explosions.

Tentative Bureau of Mines specifications for rock-dusting to

prevent coal-dust explosions in mines_.

American Engineering Standards Committee recommended stand-

ard practices for rock-dusting--------

Liability-insurance underwriters approve rock-dusting ---

Methods of applying rock dust-------

Rock-dusting machines for use in gassy mines...

Rock-dusting on slope roads---

Rock-dust barriers -------

Purposes of rock-dust barriers--------

Rock-dusting versus watering-------

Summary of facts regarding coal-dust explosions and their prevention.

Coal-dust explosions in tipples and shafts_

Ignition of gas or bituminous coal dust by explosives---

What are permissible explosives?---

Specifications for a permissible explosive---

Conditions prescribed for use of permissible explosives----

· Conditions under which a permissible explosive should not

be used ----

Recommendations on preventing ignition of gas or coal dust...

Electric shot firing from surface_-

Explosives accidents other than those causing ignition of gas or

dust--------------

---

Summarized recommendations on the transportation, storage,

and use of explosives in coal mines_-

Mine lights as a cause of explosions---

Safety lamps --------

Permissible flame safety lamps_-

Miners' permissible electric lamps_-

Explosions caused through ignition of gas by open lights_-

Bureau of Mines policy regarding miners' lamps----------

Stationary lamps in coal mines--------

Lighting in and around the return exits of gassy mines--

Electrical machinery --------

Electric power lines in gassy mines.

Portable storage batteries for mining machinery ---

Electric circuits in coal mines_

Circuits leading underground ----

Underground power, lighting, and miscellaneous circuits.

Liability of electrical machinery and circuits to ignite gas-----

Explosions caused by electric circuits in haulage ways.

Limiting use of trolley locomotives to avoid ignition of gas and

coal dust ---

---------

Combination trolley locomotives, including trolley ----------

Permissible storage-battery locomotives

Explosions and fires from leakage of natural gas and oil wells

through coal mines.-

----------

Size of pillars around wells---

Precautions recommended for gas and oil wells driven through

coal mines------

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Explosions of gas or coal dust-Continued.

Barricades and refuge chambers-----

Barricades.----

Refuge chambers_-

Falls of ground ---------------

Timbering to minimize falls--

Discussion-------

Timbering in rooms for roofs of average strength------

Entries

Timbering in pillar workings and retreating longwall..

Recommendations for prevention of accidents from falls.

Haulage accidents

Precautions----

Installations recommended for safety-----

Electric shocks_

Mine fires --------

Classification of mine fires--------

Discussion of different types---

Prevention of mine fires-----

Illinois laws governing fire prevention at mines.-

Fire-fighting equipment and organization ------

Discussion of fire-fighting equipment----

1. Water-------

2. Fire-fighting appliances ---------

3. Brattice material for building fire stoppings----

4. Telephone and alarm apparatus---

5. Emergency fire doors_-

6. Breathing apparatus---

7. Arrangement of ventilating fan---

8. Fire-fighting organization and maps--

Gas-analysis apparatus.

Fire-fighting procedure_-----

Sealing a mine fire.

Recovering a sealed fire area----

Miscellaneous underground accidents-----

Accidents from haulage animals_-.

Inrushes of water and sand--------

Prevention of accidents.

Other miscellaneous accidents.---

Accidents in shafts and along slopes-----

Safety measures --------

Speed of hoisting and lowering men in shafts and slopes

Shaft-hoisting signal devices.

Surface accidents at coal mines---

Accidents from surface inflammations of coal dust.

Organization, administration, and regulation --------

Organization at coal mines to prevent accidents---

Mine rescue and fire-fighting organization -

Crews-training and apparatus------

Federal mine rescue activities__

State mine rescue organizations_------

Local and central mine rescue stations----

Character of apparatus at rescue stations-

Gas masks-----

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