Prevention of accidents due to explosions underground in coal mines 43005 ILO Codes of Practice Prevention of accidents due to explosions underground in coal mines International Labour Office Geneva ISBN 92-2-101062-7 First published 1974 ILO publications can be obtained through major booksellers or ILO local offices in many countries, or direct from ILO Publications, International Labour Office, CH-1211 Geneva 22, Switzerland. A catalogue or list of new publications will be sent free of charge from the above address. Printed by Atar, Geneva, Switzerland Contents Page Introduction 1 1. General 3 1.1. Definitions 3 1.2. General principle of present code 4 1.3. Other applicable provisions 4 2. Ventilation 6 2.1. General principles 6 2.2. Ventilation plans 7 2.3. Supervision of ventilation systems and equipment 9 2.4. Ventilating fans below ground 10 2.5. Gas emission and ventilation requirements 11 2.6. Stagnant zones and vulnerables places 14 2.7. Ventilation of stable holes 16 2.8. Interruption in firedamp drainage system 16 3. Emission of firedamp 18 3.1. Rapidly advancing faces 18 3.2. Strata control 18 3.3. Cavities 19 3.4. Formation and dispersion of thin gas layers 20 4. Detection of gas 21 4.1. Inspection 21 4.2. Exceptional conditions 22 4.3. Gas plug in roadway 23 4.4. Gas testing and air sampling 23 5. Sources of ignition 26 5.1. General 26 5.2. Restrictions on use of light alloy equipment 26 5.3. Shot-firing 27 5.4. Electrical apparatus 28 5.5. Fires 29 5.6. Flammable materials 31 v Prevention of accidents due to explosions Page 5.7. Flammable liquids 31 5.8. Open or naked lights 31 5.9. Contraband 32 5.10. Inspection 32 6. Coal dnst 33 6.1. General 33 6.2. Application of water 33 6.3. Stone dust or water barriers 34 6.4. Stone dusting at roadbeads of conveyor roadways 34 6.5. Use of hygroscopic salts 35 6.6. Treatment of coal dust in wet conditions 35 7. Human factors . 36 vi Introduction This code of practice, although couched in the language of a set of rules, has no binding force and is not intended to super­ sede national laws or regulations or accepted standards; it is merely a body of practical advice for the use of all those, in both the public and the private sector, who have responsibility for safety in coal mines. The value of the code lies in the fact that it em­ bodies the knowledge and experience of many countries. It has been drawn up to provide guidance for persons who may be framing provisions on this subject, particularly in government, in management and on safety committees, including persons planning new mines or engaged in the alteration or extension of existing mines. The explosion hazard in mines arises from many causes and is erratic in its incidence.1 Research into the underlying problems of the mine environment itself and into the prevention of initiation of explosions has provided a fund of knowledge which can con­ tribute largely to a reduction of such occurrences. Other impor­ tant factors are the human element and the effects of mechanisation and new methods of production. All these factors demand that an ample margin of safety be allowed in planning and that continual vigilance be maintained in all mining operations if explosions are to be prevented. The International Labour Organisation has for many years promoted higher standards of safety and health in underground 1 Among the points that have come to light during the preparation of this code is the question of gassy or non-gassy mines. The classification of mines into these two groups is controversial; however, all coal mines are potentially gassy and this fact should be taken into account both when planning and when operating such mines. Attention is also drawn to the fact that a number of mines other than coal mines in different parts of the world are known to be also subject to firedamp emissions, and that many of the provisions of this code are therefore equally applicable in such cases. 1 Prevention of accidents due to explosions mining, especially for coal. In particular, it published in 1950 a Model code of safety regulations for underground work in coal mines, for the guidance of governments and of the coal-mining industry. Two codes of practice, on the prevention of accidents due to fires and electricity underground in coal mines, were published in 1959 after the Office had consulted a number of experts and had come to the conclusion that it should deal successively with selected branches of mine safety rather than once again endeavour to cover the whole subject in a single comprehensive set of rules. The present code of practice has been prepared in the light of the above-mentioned conclusion. A preliminary draft prepared by the International Labour Office was submitted for comments and observations to the 28 members of an ILO panel of consultants on safety in mines. This panel is composed of consultants spe­ cialising in the various aspects of the subject and includes persons from different countries who reflect the views and experience of governments and of employers' organisations and trade unions in the mining industry. Their observations and comments were embodied in a second draft which was also submitted to the panel, and the present consolidated text has been prepared in the light of that second consultation. This document was approved for publication by the Governing Body of the International Labour Office at its 189th Session (February-March 1973). 2 1. General 1.1. Definitions 1.1.1. In this code of practice— (a) the term "competent authority" means a minister, govern­ ment department or other public authority having powers to issue regulations, orders, decrees or other instructions having the force of law in respect of safety in coal mines, or an authority entrusted with the enforcement of such regulations or instructions; (b) the term "manager" means a duly qualified and appointed person legally responsible for the management and technical direction of the mine, whether he is the mine operator or a person appointed by him; (c) the term "supervisory official" means a person appointed by the manager to supervise or perform certain work, or to supervise the operation of certain machinery, plant, or equip­ ment, and who is competent and responsible for the duties so assigned to him, and has been provided by the manager with the necessary instructions and facilities for their proper performance; (d) the term "authorised person" means a person appointed or selected by the manager to carry out special duties and com­ petent and responsible for the work he has been directed to perform; (e) the term "shot-firer" means a person authorised to fire shots under conditions specified in national laws or regulations; (f) the term "face" means the moving front of any working place, entry, slope or drift; (g) the term "firedamp" means any flammable gas, chiefly meth­ ane, given off from the coal or other strata in a mine; and 3 Prevention of accidents due to explosions (h) the term "auxiliary fan" means a fan the use of which is confined to the ventilation of a localised stagnant zone such as a heading, drift or blind end. 1.2. General principle of present code 1.2.1. In the planning and operation of a coal mine, or any part of such a mine, all practicable precautions should be taken not only to prevent explosions of flammable gas and coal dust but also, in the event of an explosion, to limit its extension or spread. 1.3. Other applicable provisions 1.3.1. Shot-firing, if practised, should be carried on in com­ pliance with the statutory regulations in force at the time in the country concerned, with the relevant requirements of the ILO Model Code of Safety Regulations for Underground Work in Coal Mines 1 (hereinafter called the Model Code), or requirements at least equally strict. 1.3.2. If electrical apparatus is installed, it should be used in accordance with— (a) the statutory regulations in force at the time in the country concerned; (b) the relevant provisions of the Model Code; and (c) the provisions of the code of practice on the prevention of accidents due to electricity underground in coal mines2, or requirements at least equally strict. 1 ILO: Model code of safety regulations for underground work in coal mines, for the guidance of governments and of the coal-mining industry (Geneva, 1950). 2 Idem: Prevention of accidents due to electricity underground in coalmines (Geneva, 1959). 4 General 1.3.3. Precautions against firedamp should comply with— (a) the statutory regulations in force at the time in the country concerned; (b) the relevant provisions of the Model Code; (c) the provisions of the code of practice on the prevention of accidents due to fires underground in coal mines \ or require­ ments at least equally strict; and (d) the relevant provisions of this code of practice. 1.3.4. Precautions against coal dust should comply with— (a) the statutory regulations in force at the time in the country concerned; (b) the relevant requirements of the Model Code; (c) the relevant recommendations 2 of the ILO meetings of ex­ perts on the prevention and suppression of dust in mining, tunnelling and quarrying or requirements at least equally strict; (d) the relevant recommendations and advice to be found in the Guide to the prevention and suppression of dust in mining, tunnelling and quarrying 3; (e) the relevant provisions of this code of practice.