EIACP (PC-RP) on Environmental Problems of Mining

New Moghla Colliery

New Moghla coal mine is situated at a distance of about 120 km from Jammu and about 26 km from Kalakot in the Rajouri district of Jammu & Kashmir State.

The upper coal measures in this coalfield have some thin coal beds varying in thickness from 10 cm to about 1.5 m and are mostly unworkable. The lower coal measures contain one workable coal seam of I m to 9 m thickness. Due to intense geo-tectonic movements, the strata are folded and affected by small and large faults. The coal is semi-anthracitic with low volatile matter (around 13%) and high sulphur content (1.8 to 2.9%). Small opencast mines are worked manually at several places along the 80 km long coal belt. A few underground mines are worked through inclines which have mostly been opened out from the opencast workings. The underground mines are developed on the bord and pillar system with square or rectangular pillars ranging from 20 m to 30 m in size. No depillaring is done except in one mine where splitting of pillars is done as the final operation. The coal is soft and no explosives are used in belowground mines. The overlying strata are weak and need extensive support. Cross-bars on vertical props with laggings are the standard support used in mine roadways.

New Moghla mine had two separate sets of belowground workings. One set of workings, made through Incline Nos. 5,6 and 7, had extended upto a distance of 60 m along the dip whereas the second set, worked through No.1,2 and 3 Inclines, had extended upto the 14th level where the depth from the surface was about 100 m. The galleries are 2 m to 2.5 m in width and 2 m in height. At places, the height had increased due to roof falls and cavities had formed in the roof. The coal seam in the area is gassy but no gas survey had ever been carried out at New Moghla mine. However, it was declared a gassy seam of the second degree on the basis of gas emission in the adjoining Metka Colliery.

Coal production at New Moghla was done in two shifts: 8 a.m. to 4 p.m. and 4 p.m. to 12 mid night. The weekly day of rest was Sunday. The average daily production was 60 t and average employment below ground was 200.

The accident occurred in the workings made through Incline Nos.l, 2 and 3. These workings were ventilated by a 25 H.P. axial flow fan, locally made and fitted at the mouth of Incline No.3 which was the main return airway. It was exhausting about 430 m3/min of air at a pressure of 25 mm of water gauge. An auxiliary fan was installed in 12th level north, close to the 1st rise, for conducting air to the working faces through tubings made of brattice cloth. Inflammable gas had been detected in the workings by overmen with methanometers from time to time; the maximum concentration reported being 1.5%. At the time of the accident 123 persons were present belowground.

A gas explosion occurred at about 1.15 p.m. on 3.3.1997 (Monday) in the 121 level north workings. 4 workers were burnt to death and 5 workers were trapped in a blind gallery due to a fall of roof triggered by the explosion. 3 workers in the main dip near 12 level received burn injuries while 10 others were injured by debris thrown by the explosion. One worker, partly buried beneath the roof fall, was extricated alive but he succumbed to his burn injuries on 10.3.1997. The 5 trapped miners could be reached only at 4 p.m. on 7.3.97 by which time they had died due to asphyxiation.

After the explosion, detailed investigations were carried out by officers of the DGMS to ascertain the emission of inflammable gas from the seam, the likelihood of gas layering with the auxiliary fan running and accumulation of gas in blind headings with long stoppage of the auxiliary fan. It was found that the seam contained substantial quantities of methane and its rate of emission was calculated to be at least 0.21 m3/minute and 5.04 m3/t of coal produced. Even with the main fan and auxiliary fan running, layering of methane was severe in inbye galleries. Two hours after stoppage of the auxiliary fan, high concentration of methane was found in roof cavities in the blind headings.

From these studies it was concluded that when the auxiliary fan was kept stopped for 32 hours (from 00 hours on Sunday, the 2nd March to 0815 hours on 3rd March) a large quantity of gas at a high concentration had accumulated in the blind galleries and this gas was gradually diluted when the auxiliary fan was started at 0815 hours on 3.3.97 bringing it within the explosive range and spreading it to other parts of the workings. The brattice partition erected at the junction of 12 LN in the main dip was removed by the loaders, either fully or partly, to facilitate coal loading and as a result the air flow was short circuited and only a small quantity of air was reaching the auxiliary fan. Consequently, the fan re-circulated the methane- air mixture till it became explosive and was ignited to cause the violent explosion.

As to the source of ignition, the experts considered all the possible sources. There was no evidence of any underground fire. No explosives were being used and therefore shotfiring as a possible source of ignition was ruled out. ; The coal was soft and no hard band was present in the section of the seam being developed. Moreover, no worker was engaged in cutting coal at or near the origin of the explosion, Hence sparks from cutting picks could not be the source of ignition. There was no evidence of the presence of any naked light or anybody smoking. All the flame safety lamps from belowground were examined and found to be in order. Ten electric cap lamps, some worn by the deceased, were recovered from the underground workings. One of the cap lamps was severely damaged. All these cap lamps were examined by scientists at CMRI who reported that there was no possibility of any of these lamps causing the explosion. The only electrical equipment near the site of explosion was the motor of the auxiliary fan. The motor with its terminal box was run in an explosive gas chamber at CMRI and there was no ignition of the gas. Thus electric spark was also ruled out. The auxiliary fan was run in the explosive gas chamber and the gas exploded. It was concluded that frictional sparks from the fan blades caused the ignition of the gas. At the rated r.p.m. of over 3000, vibration of the fan resulted in active friction between the stationary steel duct and the rotating- aluminium alloy blades to cause frictional sparks which ignited the inflammable mixture. Tests conducted on coal samples and mine dust samples indicated that coal dust did not take part in the explosion. Due to the wet floor and pillar sides, participation of coal dust was averted; otherwise, the explosion would have been much more devastating and caused many more deaths.

Conclusion

A large volume of methane at high concentration had accumulated in the development workings on the weekly day of rest due to stoppage of the auxiliary fan. When the auxiliary fan was started the next day, the accumulated mixture was diluted till it came within the explosive range. Frictional sparks created by the auxiliary fan blades rubbing against the metallic duct ignited the gas to cause the explosion.

Observations

The general standard of management of the mine was very poor. There was severe shortage of proper electrical cables, switchgear, proper type of auxiliary fan and even building materials for construction of ventilation stoppings. Despite repeated reminders by DGMS, no rescue room had been established at the mine. Self rescuers were not provided to belowground workers as required by the CMR. Although inflammable gas had been detected in the mine from time to time, no effort was made to conduct a gas survey in the seam and no precautions were taken to deal with the problem of gas. There was a shortage of statutory personnel at the mine. No engineer had been appointed. The surveyor was appointed on part time basis and regular survey of the mine workings was not being done. Mine roadways were being driven in an unplanned manner forming irregular sized pillars. Long blind headings were being driven without making inter-connections at fixed intervals resulting in poor ventilation and accumulation of methane in the headings. There was no proper system of exercising supervision, control and management of the operations. Supervisors were not writing their daily reports regularly and nobody seemed bothered about checking the work of the supervisors.

The entire ventilation system of the mine was defective. The main fan was too small for the mine and was incapable of producing adequate ventilation in the workings. The auxiliary fan was improper in that its hub and blades were made of light aluminium alloy the use of which was prohibited by CIM because of the possibility of incendive sparks being given off when struck. There was excessive leakage of air through ventilation stoppings and doors. Adequate quantity of fresh air was not reaching the auxiliary fan with the result that it re-circulated the air. The ventilation duct was improper and could not be kept extended to within 4.5 m of the face as required. In fact, in 12 LN working areas, the ends of the ducts were as much as 35 m away from the faces. Quite often, brattice partitions were removed to facilitate coal loading thereby further depleting the air supply to the workings.

Because the mine was owned by the State Government, an attitude of taking things easy seemed to have developed at all levels. Scarcity of funds was always put forth as the reason for not implementing safety directives. On the whole, matters of safety did not receive the attention they deserved. Unless the management develops greater concern for the safety of its workers, such accidents cannot be prevented.