Date of the Accident – 28.5.1965
Owner – Bokaro & Ramgarh Ltd.
Number of persons killed – 268
Place – East Bokaro Coalfield
On the night between the 27th and 28th of May, 1965, at about 1 a.m. one of the biggest disasters in the history of coal mining took place at Dhori Colliery. It caused tremendous material damage and killed 268 persons, this being the highest number of deaths in an explosion in India.
The Dhori Colliery has a number of seams, namely, Amlo, Upper Kargali, Lower Kargali, Bermo and the Karo group of seams including Phusro seam. At the time of the accident only the Bermo seam was being worked underground. Immediately south of the workings of the Bermo seam there was a big fault known as the Gobindapur-Pichri fault. This fault was represented by a well-defined crushed zone. The northern upthrown area was, however, relatively free from faulting, where active mining operations were carried out. The fault had brought the Upper Kargali seam of the southern downthrown block almost in juxtaposition with the Bermo seam of the northern area. Upper Kargali was known to be a gassy seam.
Upto the time of the explosion, the mine was treated as non-gassy. Naked lights (hurricane lanterns) were used in the mine for the purpose of illumination. There was no mechanical ventilator, the air being circulated by natural ventilation only.
Cause of the accident
Two rival theories had been placed before the Court of Enquiry by the parties. The theory put forward by the Department of Mines purported that there was an accumulation of firedamp within explosive limits in 15 level south of BI.10A incline prior to the accident. It was ignited by the hurricane lantern of a person who entered this gallery. The reason why the person entered the gallery, which was not being worked at the time, could not be definitely fixed. As a result of this ignition, a firedamp explosion was caused, and as there was enough fuel in the form of coal dust in all parts of the mine, a coal dust, explosion was initiated by the gas explosion which soon propagated to all the other parts of the mine.
The management, however, repudiated the above theory and held that the explosion was the result of an act of sabotage. This idea probably had its origin in the 45-day strike which was called off only a week before the day of the explosion. The Management’s theory set forth that (i) there was no gas in the mine prior to the explosion; (ii) the seat of ignition was the blind dip gallery in the 9th level east in Amlo Incline; and (iii) the explosion in the aforesaid gallery was due to a coal fire intentionally ignited by human agency which came into contact with some kind of explosive substance such as gunpowder or gelatine placed in a container.
The management’s theory was completely demolished during the cross-examination of the manager and other witnesses. Moreover, the seat of the explosion as suggested by the management did not fit in with the general direction of propagation of the explosion. The Court therefore supported the theory put forth by the Department of Mines and accepted the cause of the accident as firedamp explosion initiating a series of coal dust explosions, the seat of ignition being near the dead body in 15 south level of BI.10A incline. The contributory causes of the accident were (i) lack of ventilation, (ii) the use of naked lights in the mine, and (iii) presence of coal dust and the failure to treat it properly.
As a result of the findings, the Court of Enquiry made the following recommendations:
- Even in non-gassy mines, all workers below-ground should be provided with electric cap lamps.
- All the mining sirdars, shotfiring sirdars and overmen must be trained to detect the presence of methane in the mine atmosphere. Endorsement for gas-testing on the certificates of all the mining sirdars, shotfiring sirdars and overmen should be revalidated periodically.
- Some common precautions should be introduced in all the mines, gassy or non-gassy, especially in the working faces. Every mine must be required to test for gas in each working face and also in all places within a distance of say 100m, from the working face by means of a more accurate and more sensitive instrument than a flame safety lamp or by analysis of samples of air. This should be done by the manager or an under-manager.
- Even in non-gassy mines, steps should be taken to ensure better ventilation. Regular measurements of air should be taken in all mines.
- The distance to which a gallery can be driven “blind” must be enforced. Normally, it should be obligatory to make ventilation connections as soon as the gallery is driven a pillar-and-a-half length or 50 m from the last ventilation connection, whichever may be more.