DISASTER IN INDIAN COAL MINES
Mining means the procedures used to extract minerals and other raw materials from the Earth. While extracting such mineral the crust of the earth is disturbed. In other words the equilibrium of the Earth crust is de-established. Virtually it is a “WAR AGAINST MIGHTY NATURE”. To fight such a war against nature is fraught with numerous dangers. Therefore,MINING is the “MOST HAZARDOUS PROFESSION ALL OVER THE GLOBE”. That is why the laws related to safety of workers is much more stringent than laws related to other production units. In spite framing laws and its implementation there is always a probability of an event causing loss of life or injury. However, working mines as per provision of the statute will naturally minimize such unwanted accidents but is impossible to eliminate it altogether.
2. ACCIDENT
2.1. Accident or Disaster has not been defined under the Mines Act , 1952 or under the Coal mines Regulations, 1957 and any other statute related to mining operation.
2.2. “ACCIDENT” may be defined as an unintended happening”. It may or may not cause death or injury to one or more persons. An accident causing loss of life or serous bodily injury or an explosion, spontaneous heating, outbreak of fire, inrush of water or gas, premature collapse of any part of the workings, overwinding of cages etc. will have to be reported whether there is a loss of life or not. This is provided under section 23 of the mines act, 1952 (read with C.M.R 9 and form IV A).
2.3. Accidents may be broadly classified into different categories.It should however, be noted that there is no clear cut demarcation of category of accident but is supported by convention.
(i) Dangerous occurrence – No loss of life or injury but only mishaps.
(ii) Reportable injury – Injury other than a serous injury.
(iii) Minor injury – Any injury other than a serious injury enforcing,absence of 24 hrs. but less than 72 hrs.
(iv) Serious injury – As an injury which involves the permanent loss of any part of the body or permanent loss of or injury to the sight or hearing or permanent physical incapacity or the fracture of any bone or joint, and or absence of 72 hours or more.
(v) Fatal accident – Which results in death of one or more persons.
(vi) Major accident – Which results in death of 4 to 9 persons.
(vii) DISASTER – Which results in 10 or more deaths.
3. DISASTER (GENERAL)
3.1 As spelt under para 2.3, a disaster in a mine is identified when 10 or more persons are killed in an accident arising out of mining operation. There are various causes of ACCIDENTS and they have been codified. However, the disasters are caused by major reasons of accidents. Coal Mines are more prone to Disasters than Mettaliferous mines. The reasons are multifold. Occurrence of inflammable gas, weak and friable strata are the main reasons. The proximity of abundant mines filled with water or gas are the other reasons making the coal mines more prone to Disasters.
3.2 The prescription under the coal mines Regulations, 1957 appears to be adequate. The Chapter (ix) – Regulations 116 to 129 is devoted on “Precautions against dangers from fire, Dust, Gas and Water”. Likewise standard of ventilation and Regulations related to Mine working (both o/c and underground) is quite exhaustive and sufficient. Unfortunately many of the Disasters have taken place before the binding statues in detail came to be the laws of Mining. Even after coming up of Regulations in 1957 and modifications and circulators have not been able to arrest the disasters. Most of the disasters are on account of lack of appreciation of the provisions under stipulated Regulations and also on account of deliberate or inadvertent neglect of the provisions.
3.3 “There is hardly any accident or disaster which is on account of”Act of God”.Severe earthquake causing damage to the mine working or flow of water into mines due to unprecedented rain etc. may sometimes be categorized as an “Act of God” but eventually has not been known so for. An enclosed diagram under the head “Accident Trend- Responsibility wise” would support the stipulation above.
3.4 If we categorize an accident causing death of 10 or more persons, there may be no. of causes of accidents but we are concerned here with the death caused by Mining or its associated activities. The main cause of “Mine Disaster” (based on no. of deaths in past)may be categorized as follows.
3.4.1:- MAIN CAUSES OF DISASTERS:
(i) EXPLOSION – GAS or Gas cum dust explosion or Dust explosion.
(ii) Inundation – In rush of water either from surface or otherwise.
(iii) Fall or collapse of roof/pillar/sides etc.- i.e. GROUND MOVEMENT.
(iv) Fire.
(v) Air blast.
(vi) Miscellaneous.
4. EXPLOSION
Although explosions account for relatively less number of deaths compared to other reasons but it causes an taken as a national calamity. Explosions are a phenomenon of underground coal mining and they may be caused by one of the following:
(a) Firedamp (Methane) alone or
(b) Coal Dust alone or
(c) Both Firedamp and Coal dust.
4.1. FIREDAMP EXPLOSION:
It is known that the “Methane” in the mixture of air between 5% to 15% is within explosive range. However, 10% of Methane exhibits maximum explosive violence. Once the explosive mixture is present in the mine air it may be ignited by any one of the following:
a) Flames from naked lights, match sticks, burning coal and oil.
b) Heated surfaces like incandescent filament of an electric lamp, overheated gauze's of flame safety lamps, bearings, rocks or metal surfaces heated by friction.
c) Sparks from electric cables and apparatus. Flame proof electrical equipments may also cause spark. Some time intrinsically safe apparatus may have induction voltage and may cause spark.
d) Explosives: Flame and hot gases given off by a shot incandescent particles ejected from the shot hole,incompletely detonated explosives continue to burn etc. If P5 explosives are not used in gassy mines there is every likelihood of an explosion.
4.2 COAL DUST EXPLOSION:
Coal dust when suspended as an cloud in the air, is also capable of propagating an explosion, even in the complete absence of Firedamp. A dense cloud of dust is required to initiate an explosion and it may propagate further with little quantity of dust as little as 50 gm of dust in one cubic meter of air space can propagate an explosion. However, it is to be noted that coal dust requires much stronger source of ignition”Coal Dust Explosions”. In such case the Firedamp explosion itself becomes the
source of ignition for coal dust. However,initiation of dust explosion by fire is an record.
4.3 Firedamp and Coal Dust explosion:
As stated earlier that purely coal dust explosion is a remote possibility, all the major disasters arising out of explosions belong to this category. In a “Gas Explosion” the shock waves and “Flame” are usually together. In a Coal dust explosion, the dust must be raised in the mine atmosphere. The shock wave of the gas explosion disperses the dust and the coal dust explosion follows thereafter the stone dust barrier,due to shock wave caused by gas explosion (which moves ahead) causes t5he dust on the barrier to fall in thick concentration and arrest the propagation af coal dust explosion. It is also to be noted that coal dust explosion is more severe than the gas explosion.
4.4 Statistics of Explosion in Indian Coal Mines:
So far 23 explosions have been recorded causing loss of 1184 lives including 50 lives lost on 6th September 2006 at Nagda Incline of Bhatdih Colliery (B.C.C.L). Maximum lives were lost at Dhori colliery on 28.5.1965 numbering 268 followed by Poidih colliery death toll of 209 on 18.12.1936. Another very high toll at 176 was at Chinakuri on 19.2.1958. The most recent incidence of explosion at Nagda, in recent past , is the highest one after Dhori.
4.5 Analysis of Explosions:
Critical analysis of the explosion reveal the following:
a) Most of the explosions are on account of “Methane Gas”.
b) Many gas explosions have assumed severity on account of association of coal dust.
c) There are few gas explosions without association of dust.
d) A few explosions have been caused by ignition of dust alone. Explosion at Karharbaree was caused by ignition of coal dust due to flame from a blown out shot. At Chowrasi colliery outbreak of fire resulted in an explosion in which Coal Dust played a prominent role.
e) Many of the gas explosions have taken place due to defective “Flame safety lamp”.
f) Most of the explosions could have been everted if the extant “Regulations” could have been abided.
An extract from the book entitled “Safety in Mines” by Prof.B.K.Kejriwal, I.S.M.Dhaubeed is enclosed in respect of the following explosions. The details of explosions:
1 Dhori colliery 28/05/65 -268(Mix-Gas/Dust)
2 Chinakuri colliery 19/02/58 -176(Mix-Gas/Dust)
3 Jeetpur colliery 18/03/73 -48(Gas Explosion)
4 Karharbaree colliery 24/07/35 -62(Dust Explosion)
However, it is advisable to go into the details of other explosions also for acquoring indepth study on explosions.
5. INUNDATION
5.1. In addition to water Oozing out of strata at depth inflow of water may either be from surface sources or from underground. The water may rush from the present working or from abandoned working situated on the surface or on the other side of “Barrier”. The inflow of water at work place does not allow time to the workers to move out and such incidence cause DISASTER.
5.2. “Surface water may flow to workings on account of water flowing through river or nallah and stagnant water of tanks and reservoirs”.Accumulated water in old open cast working is also a source of water endangering nearby underground or even opencast mine. Water accumulated in low lying area(above the Mine working) is another source of water endangering the working. Incessant rain may some time cause inundation.
5.3 The stored water in underground lying above the level of working is a source of danger causing inundation. Old water logged workings either in the same seam or in another. Water sump, water logged area in the adjoining mine, highly water- bearing strata over lying the working seam are the sources of water flowing underground working.
5.4 Surface water may drown or inundate the mines through shafts and inclines or broken ground over caved graves, boreholes or Geological disturbances like faults. Another important consideration is collapse of over lying strata by “POTHOLING”, “Subsidence” caused either by inadequate stowing or collapse of pillar. The underground water may flow into workings on account of “Accidental connection” “Development of cracks”, “Fissures and Fractures”, “Failure of barrier pillars or parting”, “failure of dams”etc.
5.5 The most important point to be kept in mind is to be very-very careful wherever mine working approaches any lodgment of water either on the surface of water or underground. Sometimes plan and sections available are not reliable. Reduced level of surface is not properly co-related with the underground R.L.The barriers may be thinned out or robbed but shown intact. Misleading information and undue risks are the most common reasons of the “INUNDATION and RESULTANT
DISASTER”.
5.6. STATISTICS OF INUNDATION DISASTERS:
The first recorded inundation disaster was on 11.07.1912 at Phularitand colliery. It is to be noted that INUNDATION DISASTER OF CHASNALA COLLIERY IS THE GREATEST MINE DISASTER IN THE COLLIERY taking a toll of 375 lives. The total no. of persons killed in Inundation disaster work out to 720 and is next to explosion disaster causing 63 and 28 deaths were at Newton Chikli and Burra Dhemo colliery respectively. Gaslitand disaster is fresh in our mind causing 64 deaths on 27.09.1995.Bagdigi disaster causing death of 29 persons on 02.02.2001 is the latest on record of Inundation Disaster. A list of Inundation disaster is enclosed with this write -up. Detail of Chasnala, Central Saunda and Hurladih Inundation is enclosed.
5.7 Summary of inundation disaster starting from 1912 and till 1983 (extract from the book by Prof.Kejriwal) is enclosed for study by participants and readers of this write-up.
6. ROOF FALL & GROUND MOVEMENT DISASTERS
6.1 “ROOF FALL” and “GROUND MOVEMENT” is the “NUMBER ONE” killer. However, most of such accidents do not cause death of 10 or more number of workers.58% of fatalities and 20% of serious accidents have been recorded on account of Roof Fall and Ground Movement. Therefore , the DISASTERS on the above count is relatively at lower level. All the same undesirable “Roof Fall” and “Ground Movement” must be taken care of.
6.2 Disasters on account of Roof fall and Ground movement: As stated earlier the number of persons killed in such accident is normally less than 10. However, on record there are 3 incidences of roof fall which can be categorized as “Disasters” and is tabulated below:
SI.
No. Name of Mine Date of
occurrence
No. of
persons killed
1 Sitalpur 15/10/10 12
2 Kessurgarh 09/08/75 11
3 Topa 16/07/82 16
The Disasters both at Sitalpur and Topa occurred on account of loaders engaged in loadind coal from “GOAF”.At Kessurgarh colliery the gallery was heightened upto the roof and extraction of a stook had been started. 16 shot holes were blasted in the corner of stook and soon after blasting loaders were engaged to load the coal. As per S.S.R. There should have been at last 20 props and 2 cogs to support the junction of the gallery. The unsupported junction was the source of accident. Sand stone roof measuring about 10m *7m (70 sq.m) and 15 to 30 cm thick fell at the junction killing 12 persons and injuring few others.
6.3. DISASTERS DUE TO FAILURE OF PILLARS:
One of the hazards of Pillar Mining is the possibility of Collapse of pillars.The collapsa of pillars may be gradual or sudden. Sudden collapse causes disasters. In 1960 in “South African Coal Brook North Colliery” an area of over 2.5 sq.km.,standing on pillars have caused subsidence of the surface and have resulted in extensive fire in the coal field due to spontaneous combustion of the crushed coal. They have invariably been associated with severe “AIR BLAST”. The accidents take place because the standing pillar is not capable of sustaining the load of the overlying strata. The Barracks accomodating workers above the developed pillars have collapsed at “Chanda colliery” and also at “Bhowrah colliery”. The list of pillar collapse causing disasters is tabulated below:
DISASTER PILLAR COLLAPSE:
SI.No. Name of Mine Days of
Occurance Death
1 Chanda 31/08/15 10
2 Bhowrah 04/02/16 24
3 Rawanwara 14/04/23 15
4 West Chirimiri 11/04/68 14
Measurement of stress on the pillar should be carried out to detect the probability of collapse of pillars.
6.4. SIDE FALL DISASTERS IN OPEN CAST MINES:
Fall of sides in open cast takes place if the benches are not formed properly. In other words if there is either an “over hang” or “vertical face” there is every likelihood of the fall of the face (side). Depending on the magnitude of the fall and persons around such fall a disaster may be caused. Any Geological disturbance (faults and other ones causing weakness of the strata)will aid to the danger. In such cases the slope of the bench should be minimized. Danger should also be apprehended if the
working by open cast mining method extends towards the developed pillars. The inconsistent strata (say clay or black cotton soil) also demands adequate care and gentle slope of the bench. On 24.06.2000 a disaster took place at KAWADI mine of Majri area (W.C.L) killing 10 persons. This was a result of excessive height of the bench. It had Black cotton soil. The maximum height permitted was only 5 m and for normal strata it was 10m. However, the working was combined and height of the bench was in excess. One of the workers noticed loose debris falling from the top of the benches on the rise (barrier) side. By the time he could raise an alarm, loose debris and boulders started sliding down rapidly into the quarry. 10 persons were trapped but 5 could escape. The total volume of material that slid was more than 20000 cubic metres. There have been many disasters in metaliferrous mines on this count.
7. FIRE – DISASTER
7.1. Fire is one of the most serious hazards in under-ground mining because an
underground fire can fill a mine with deadly Carbon Monoxide gas in minutes.
This rapid rate of contamination coupled with the long period of time needed to
evacuate workers, can make even a small fire a potential source of
“DISASTER”.
7.2. The reasons of fire in underground is well-known. Most of the fires owe their
origin to spontaneous combustion of coal.Precaution against fire has been
detailed under C.M.R 1957 (Regulations 116 A to 122) and are well known to
practicing Mining Engineers. However, it is to be reminded that any fire either
on surface or underground should be taken very seriously. Most important
action to be taken is to detect the symptoms of fire at initial stage and deal with
them promptly.
7.3. The “Disasters” at “Loyabad colliery” on 30.01.1936 killing 35 persons is a
typical example of fire in the underground. The fire prolongs if fresh air with
oxygen reaches the fire. Here, the fire broke out near an “Air crossing”. The
intake and Return air got mined up and the fire became devastative. Many
workers moved out but 35 were killed.
Another disaster due to fire in recent past occurred at “NEW KENDA” colliery
(E.C.L) on 25.01.1994 killing 55 persons . The fire was caused by
spontaneous haeting of roof coal. It could not be detected because of very
efficient ventilation.
The cool aur was flowing but the coal in the roof was the source of fire which
came down and the incoming aur helped burning of such fallen banded Shaly
coal. The “Court of Injury” did not find any body responsible because nobody
had defaulted in his duty in preventing or detecting the fire.
8. AIR BLAST DISASTERS:
8.1. If dipillaring is carried out by “CAVING” method and the roof does not fall as
desired and large area remains hanging even after withdrawl of support there
is a grave danger of “AIR BLAST”. Fall of large area of roof at a tine suddenly
expels huge quantity of air.If only a few outlets are available the speed of air is
even higher than HURRICANE speed. Such speedy air causes all sort of
damages to the underground mine and persons in line with such speedy air
has little chauee to survive.
8.2. The “BEAUFORT” scale of wind force suggests that the air speed between
33m to 60 m. per second is categorized as Hurricane speed. “The BEAUFORT
scale of wind force” is also enclosed under this write up.
8.3. “Air Blast” may be caused by collapse of pillar in Coal Mines. The examples
are “Rawanwara and Wst Chirimiri” collieries.
8.4. Disaster due to AIRBLAST IN COAL MINES are known to have happened at
Jamuria and parascole west collieries.
8.4.1. Jamuria:- 08.10.1943 (12 killed). The overlying roof over the depillaring
district was ”MASSIVE SANDSTONE “ about 26 m thick. The cover
over the panel was 137 cm. The roof in the entire Goaf area measuring
about 120 m *100m had been standing for long. On the day of accident
it fell on a sudden without ant warning. All the persons were blown off
their feet and infrastructure of mine was damaged severely.5 people
died on the spot and rest subsequently. Only 2 lives could be saved.
8.4.2. Parascole West colliery (E.C.L) 06.07,1999- 5 killed.Though it is not
categorized as “DISASTER” it is worth noting that here also the
standing roof came down suddenly. The main roof in the goaf over an
area of 75m * 78 m along 130m *78m of the adjoining sealed off area
fell suddenly.
9. DISASTERS
9.1. Miscellaneous category:
The two disasters namely at Jagarnath colliery (now in M.C.L- at
the time of accident it was in C.C.L) and Central Saunda (C.C.L) should
not be categorized under any head spelt above. Jagarnath colliery(open
cast) has been categorized under “FIRE DISASTER” by Prof.Kejriwal
but I have a different opinion for the reasons explained later. Likewise
recent disaster at Central Saunda can also not be categorized unde” Air
Blast” or “INUNDATION” because there were both. There was an air
blast which caused inundation also. A brief mention on both the
disasters will be necessary.
9.2. Jagarnath 24.06.1989- 10 killed,it has two quarries namely the “Pilot”
and “Main” quarry.The accident occurred in Pilot quarry which was
located in the “THROUGH” of two strike faults. The mine was operated
by “Dragline”, “Shovel Dumpers”, “Pay loaders” etc. at about 52 m
depth. Priorto accident there was heavy rainfall for 4 days. A pump was
being installed by a contractor who had engaged 13 workers. The Coal
seam was prone to “Spontaneous heating”.
There were divergent views on the reasons of the disaster. They were
killed by large/small sized stone/Burnt coal pieces hitting the persons.
The small pieces of 6 to 8 cm. were thrown to a distance of around
60m. The slide might have been caused by fire, heavy rain, presence
of fault plane, water entering through wide cracks on the surface etc. or
more probably by a combination of all these. It was apprehended that
there was an “WATER GAS EXPLOSION”( a mixture consisting mostly
of H2 and CO). Another reason as mentioned by the “Court of Inquiry”
was the possibility of generation of superheated steam at high
pressure. “The court of enquiry” over ruled the possibility of “Water gas
explosion” by mentioning that such explosion cannot cause a throw of
1.5 kg clinker to a distance of 130m. “WHOA-WHOA” sound was heard
immediately after the incident supporting the possibility of generation
of superheated steam.
The facts remain that the actual reason could not be established. It
was a unique DISASTER in open cast mines.
9.3. Central Saunda (C.C.L),15.06.2005-14 lives.
In this very mine there was an Inundation on 16.09.1976 causing
death of 10 persons. The disaster on 15.06.2006 is a mix of Air blast
followed by an Inundation. The detail will be explained through “Plan”
and “Section”.
(ii) Reportable injury – Injury other than a serous injury.
(iii) Minor injury – Any injury other than a serious injury enforcing,absence of 24 hrs. but less than 72 hrs.
(iv) Serious injury – As an injury which involves the permanent loss of any part of the body or permanent loss of or injury to the sight or hearing or permanent physical incapacity or the fracture of any bone or joint, and or absence of 72 hours or more.
(v) Fatal accident – Which results in death of one or more persons.
(vi) Major accident – Which results in death of 4 to 9 persons.
(vii) DISASTER – Which results in 10 or more deaths.
3. DISASTER (GENERAL)
3.1 As spelt under para 2.3, a disaster in a mine is identified when 10 or more persons are killed in an accident arising out of mining operation. There are various causes of ACCIDENTS and they have been codified. However, the disasters are caused by major reasons of accidents. Coal Mines are more prone to Disasters than Mettaliferous mines. The reasons are multifold. Occurrence of inflammable gas, weak and friable strata are the main reasons. The proximity of abundant mines filled with water or gas are the other reasons making the coal mines more prone to Disasters.
3.2 The prescription under the coal mines Regulations, 1957 appears to be adequate. The Chapter (ix) – Regulations 116 to 129 is devoted on “Precautions against dangers from fire, Dust, Gas and Water”. Likewise standard of ventilation and Regulations related to Mine working (both o/c and underground) is quite exhaustive and sufficient. Unfortunately many of the Disasters have taken place before the binding statues in detail came to be the laws of Mining. Even after coming up of Regulations in 1957 and modifications and circulators have not been able to arrest the disasters. Most of the disasters are on account of lack of appreciation of the provisions under stipulated Regulations and also on account of deliberate or inadvertent neglect of the provisions.
3.3 “There is hardly any accident or disaster which is on account of”Act of God”.Severe earthquake causing damage to the mine working or flow of water into mines due to unprecedented rain etc. may sometimes be categorized as an “Act of God” but eventually has not been known so for. An enclosed diagram under the head “Accident Trend- Responsibility wise” would support the stipulation above.
3.4 If we categorize an accident causing death of 10 or more persons, there may be no. of causes of accidents but we are concerned here with the death caused by Mining or its associated activities. The main cause of “Mine Disaster” (based on no. of deaths in past)may be categorized as follows.
3.4.1:- MAIN CAUSES OF DISASTERS:
(i) EXPLOSION – GAS or Gas cum dust explosion or Dust explosion.
(ii) Inundation – In rush of water either from surface or otherwise.
(iii) Fall or collapse of roof/pillar/sides etc.- i.e. GROUND MOVEMENT.
(iv) Fire.
(v) Air blast.
(vi) Miscellaneous.
4. EXPLOSION
Although explosions account for relatively less number of deaths compared to other reasons but it causes an taken as a national calamity. Explosions are a phenomenon of underground coal mining and they may be caused by one of the following:
(a) Firedamp (Methane) alone or
(b) Coal Dust alone or
(c) Both Firedamp and Coal dust.
4.1. FIREDAMP EXPLOSION:
It is known that the “Methane” in the mixture of air between 5% to 15% is within explosive range. However, 10% of Methane exhibits maximum explosive violence. Once the explosive mixture is present in the mine air it may be ignited by any one of the following:
a) Flames from naked lights, match sticks, burning coal and oil.
b) Heated surfaces like incandescent filament of an electric lamp, overheated gauze's of flame safety lamps, bearings, rocks or metal surfaces heated by friction.
c) Sparks from electric cables and apparatus. Flame proof electrical equipments may also cause spark. Some time intrinsically safe apparatus may have induction voltage and may cause spark.
d) Explosives: Flame and hot gases given off by a shot incandescent particles ejected from the shot hole,incompletely detonated explosives continue to burn etc. If P5 explosives are not used in gassy mines there is every likelihood of an explosion.
4.2 COAL DUST EXPLOSION:
Coal dust when suspended as an cloud in the air, is also capable of propagating an explosion, even in the complete absence of Firedamp. A dense cloud of dust is required to initiate an explosion and it may propagate further with little quantity of dust as little as 50 gm of dust in one cubic meter of air space can propagate an explosion. However, it is to be noted that coal dust requires much stronger source of ignition”Coal Dust Explosions”. In such case the Firedamp explosion itself becomes the
source of ignition for coal dust. However,initiation of dust explosion by fire is an record.
4.3 Firedamp and Coal Dust explosion:
As stated earlier that purely coal dust explosion is a remote possibility, all the major disasters arising out of explosions belong to this category. In a “Gas Explosion” the shock waves and “Flame” are usually together. In a Coal dust explosion, the dust must be raised in the mine atmosphere. The shock wave of the gas explosion disperses the dust and the coal dust explosion follows thereafter the stone dust barrier,due to shock wave caused by gas explosion (which moves ahead) causes t5he dust on the barrier to fall in thick concentration and arrest the propagation af coal dust explosion. It is also to be noted that coal dust explosion is more severe than the gas explosion.
4.4 Statistics of Explosion in Indian Coal Mines:
So far 23 explosions have been recorded causing loss of 1184 lives including 50 lives lost on 6th September 2006 at Nagda Incline of Bhatdih Colliery (B.C.C.L). Maximum lives were lost at Dhori colliery on 28.5.1965 numbering 268 followed by Poidih colliery death toll of 209 on 18.12.1936. Another very high toll at 176 was at Chinakuri on 19.2.1958. The most recent incidence of explosion at Nagda, in recent past , is the highest one after Dhori.
4.5 Analysis of Explosions:
Critical analysis of the explosion reveal the following:
a) Most of the explosions are on account of “Methane Gas”.
b) Many gas explosions have assumed severity on account of association of coal dust.
c) There are few gas explosions without association of dust.
d) A few explosions have been caused by ignition of dust alone. Explosion at Karharbaree was caused by ignition of coal dust due to flame from a blown out shot. At Chowrasi colliery outbreak of fire resulted in an explosion in which Coal Dust played a prominent role.
e) Many of the gas explosions have taken place due to defective “Flame safety lamp”.
f) Most of the explosions could have been everted if the extant “Regulations” could have been abided.
An extract from the book entitled “Safety in Mines” by Prof.B.K.Kejriwal, I.S.M.Dhaubeed is enclosed in respect of the following explosions. The details of explosions:
1 Dhori colliery 28/05/65 -268(Mix-Gas/Dust)
2 Chinakuri colliery 19/02/58 -176(Mix-Gas/Dust)
3 Jeetpur colliery 18/03/73 -48(Gas Explosion)
4 Karharbaree colliery 24/07/35 -62(Dust Explosion)
However, it is advisable to go into the details of other explosions also for acquoring indepth study on explosions.
5. INUNDATION
5.1. In addition to water Oozing out of strata at depth inflow of water may either be from surface sources or from underground. The water may rush from the present working or from abandoned working situated on the surface or on the other side of “Barrier”. The inflow of water at work place does not allow time to the workers to move out and such incidence cause DISASTER.
5.2. “Surface water may flow to workings on account of water flowing through river or nallah and stagnant water of tanks and reservoirs”.Accumulated water in old open cast working is also a source of water endangering nearby underground or even opencast mine. Water accumulated in low lying area(above the Mine working) is another source of water endangering the working. Incessant rain may some time cause inundation.
5.3 The stored water in underground lying above the level of working is a source of danger causing inundation. Old water logged workings either in the same seam or in another. Water sump, water logged area in the adjoining mine, highly water- bearing strata over lying the working seam are the sources of water flowing underground working.
5.4 Surface water may drown or inundate the mines through shafts and inclines or broken ground over caved graves, boreholes or Geological disturbances like faults. Another important consideration is collapse of over lying strata by “POTHOLING”, “Subsidence” caused either by inadequate stowing or collapse of pillar. The underground water may flow into workings on account of “Accidental connection” “Development of cracks”, “Fissures and Fractures”, “Failure of barrier pillars or parting”, “failure of dams”etc.
5.5 The most important point to be kept in mind is to be very-very careful wherever mine working approaches any lodgment of water either on the surface of water or underground. Sometimes plan and sections available are not reliable. Reduced level of surface is not properly co-related with the underground R.L.The barriers may be thinned out or robbed but shown intact. Misleading information and undue risks are the most common reasons of the “INUNDATION and RESULTANT
DISASTER”.
5.6. STATISTICS OF INUNDATION DISASTERS:
The first recorded inundation disaster was on 11.07.1912 at Phularitand colliery. It is to be noted that INUNDATION DISASTER OF CHASNALA COLLIERY IS THE GREATEST MINE DISASTER IN THE COLLIERY taking a toll of 375 lives. The total no. of persons killed in Inundation disaster work out to 720 and is next to explosion disaster causing 63 and 28 deaths were at Newton Chikli and Burra Dhemo colliery respectively. Gaslitand disaster is fresh in our mind causing 64 deaths on 27.09.1995.Bagdigi disaster causing death of 29 persons on 02.02.2001 is the latest on record of Inundation Disaster. A list of Inundation disaster is enclosed with this write -up. Detail of Chasnala, Central Saunda and Hurladih Inundation is enclosed.
5.7 Summary of inundation disaster starting from 1912 and till 1983 (extract from the book by Prof.Kejriwal) is enclosed for study by participants and readers of this write-up.
6. ROOF FALL & GROUND MOVEMENT DISASTERS
6.1 “ROOF FALL” and “GROUND MOVEMENT” is the “NUMBER ONE” killer. However, most of such accidents do not cause death of 10 or more number of workers.58% of fatalities and 20% of serious accidents have been recorded on account of Roof Fall and Ground Movement. Therefore , the DISASTERS on the above count is relatively at lower level. All the same undesirable “Roof Fall” and “Ground Movement” must be taken care of.
6.2 Disasters on account of Roof fall and Ground movement: As stated earlier the number of persons killed in such accident is normally less than 10. However, on record there are 3 incidences of roof fall which can be categorized as “Disasters” and is tabulated below:
SI.
No. Name of Mine Date of
occurrence
No. of
persons killed
1 Sitalpur 15/10/10 12
2 Kessurgarh 09/08/75 11
3 Topa 16/07/82 16
The Disasters both at Sitalpur and Topa occurred on account of loaders engaged in loadind coal from “GOAF”.At Kessurgarh colliery the gallery was heightened upto the roof and extraction of a stook had been started. 16 shot holes were blasted in the corner of stook and soon after blasting loaders were engaged to load the coal. As per S.S.R. There should have been at last 20 props and 2 cogs to support the junction of the gallery. The unsupported junction was the source of accident. Sand stone roof measuring about 10m *7m (70 sq.m) and 15 to 30 cm thick fell at the junction killing 12 persons and injuring few others.
6.3. DISASTERS DUE TO FAILURE OF PILLARS:
One of the hazards of Pillar Mining is the possibility of Collapse of pillars.The collapsa of pillars may be gradual or sudden. Sudden collapse causes disasters. In 1960 in “South African Coal Brook North Colliery” an area of over 2.5 sq.km.,standing on pillars have caused subsidence of the surface and have resulted in extensive fire in the coal field due to spontaneous combustion of the crushed coal. They have invariably been associated with severe “AIR BLAST”. The accidents take place because the standing pillar is not capable of sustaining the load of the overlying strata. The Barracks accomodating workers above the developed pillars have collapsed at “Chanda colliery” and also at “Bhowrah colliery”. The list of pillar collapse causing disasters is tabulated below:
DISASTER PILLAR COLLAPSE:
SI.No. Name of Mine Days of
Occurance Death
1 Chanda 31/08/15 10
2 Bhowrah 04/02/16 24
3 Rawanwara 14/04/23 15
4 West Chirimiri 11/04/68 14
Measurement of stress on the pillar should be carried out to detect the probability of collapse of pillars.
6.4. SIDE FALL DISASTERS IN OPEN CAST MINES:
Fall of sides in open cast takes place if the benches are not formed properly. In other words if there is either an “over hang” or “vertical face” there is every likelihood of the fall of the face (side). Depending on the magnitude of the fall and persons around such fall a disaster may be caused. Any Geological disturbance (faults and other ones causing weakness of the strata)will aid to the danger. In such cases the slope of the bench should be minimized. Danger should also be apprehended if the
working by open cast mining method extends towards the developed pillars. The inconsistent strata (say clay or black cotton soil) also demands adequate care and gentle slope of the bench. On 24.06.2000 a disaster took place at KAWADI mine of Majri area (W.C.L) killing 10 persons. This was a result of excessive height of the bench. It had Black cotton soil. The maximum height permitted was only 5 m and for normal strata it was 10m. However, the working was combined and height of the bench was in excess. One of the workers noticed loose debris falling from the top of the benches on the rise (barrier) side. By the time he could raise an alarm, loose debris and boulders started sliding down rapidly into the quarry. 10 persons were trapped but 5 could escape. The total volume of material that slid was more than 20000 cubic metres. There have been many disasters in metaliferrous mines on this count.
7. FIRE – DISASTER
7.1. Fire is one of the most serious hazards in under-ground mining because an
underground fire can fill a mine with deadly Carbon Monoxide gas in minutes.
This rapid rate of contamination coupled with the long period of time needed to
evacuate workers, can make even a small fire a potential source of
“DISASTER”.
7.2. The reasons of fire in underground is well-known. Most of the fires owe their
origin to spontaneous combustion of coal.Precaution against fire has been
detailed under C.M.R 1957 (Regulations 116 A to 122) and are well known to
practicing Mining Engineers. However, it is to be reminded that any fire either
on surface or underground should be taken very seriously. Most important
action to be taken is to detect the symptoms of fire at initial stage and deal with
them promptly.
7.3. The “Disasters” at “Loyabad colliery” on 30.01.1936 killing 35 persons is a
typical example of fire in the underground. The fire prolongs if fresh air with
oxygen reaches the fire. Here, the fire broke out near an “Air crossing”. The
intake and Return air got mined up and the fire became devastative. Many
workers moved out but 35 were killed.
Another disaster due to fire in recent past occurred at “NEW KENDA” colliery
(E.C.L) on 25.01.1994 killing 55 persons . The fire was caused by
spontaneous haeting of roof coal. It could not be detected because of very
efficient ventilation.
The cool aur was flowing but the coal in the roof was the source of fire which
came down and the incoming aur helped burning of such fallen banded Shaly
coal. The “Court of Injury” did not find any body responsible because nobody
had defaulted in his duty in preventing or detecting the fire.
8. AIR BLAST DISASTERS:
8.1. If dipillaring is carried out by “CAVING” method and the roof does not fall as
desired and large area remains hanging even after withdrawl of support there
is a grave danger of “AIR BLAST”. Fall of large area of roof at a tine suddenly
expels huge quantity of air.If only a few outlets are available the speed of air is
even higher than HURRICANE speed. Such speedy air causes all sort of
damages to the underground mine and persons in line with such speedy air
has little chauee to survive.
8.2. The “BEAUFORT” scale of wind force suggests that the air speed between
33m to 60 m. per second is categorized as Hurricane speed. “The BEAUFORT
scale of wind force” is also enclosed under this write up.
8.3. “Air Blast” may be caused by collapse of pillar in Coal Mines. The examples
are “Rawanwara and Wst Chirimiri” collieries.
8.4. Disaster due to AIRBLAST IN COAL MINES are known to have happened at
Jamuria and parascole west collieries.
8.4.1. Jamuria:- 08.10.1943 (12 killed). The overlying roof over the depillaring
district was ”MASSIVE SANDSTONE “ about 26 m thick. The cover
over the panel was 137 cm. The roof in the entire Goaf area measuring
about 120 m *100m had been standing for long. On the day of accident
it fell on a sudden without ant warning. All the persons were blown off
their feet and infrastructure of mine was damaged severely.5 people
died on the spot and rest subsequently. Only 2 lives could be saved.
8.4.2. Parascole West colliery (E.C.L) 06.07,1999- 5 killed.Though it is not
categorized as “DISASTER” it is worth noting that here also the
standing roof came down suddenly. The main roof in the goaf over an
area of 75m * 78 m along 130m *78m of the adjoining sealed off area
fell suddenly.
9. DISASTERS
9.1. Miscellaneous category:
The two disasters namely at Jagarnath colliery (now in M.C.L- at
the time of accident it was in C.C.L) and Central Saunda (C.C.L) should
not be categorized under any head spelt above. Jagarnath colliery(open
cast) has been categorized under “FIRE DISASTER” by Prof.Kejriwal
but I have a different opinion for the reasons explained later. Likewise
recent disaster at Central Saunda can also not be categorized unde” Air
Blast” or “INUNDATION” because there were both. There was an air
blast which caused inundation also. A brief mention on both the
disasters will be necessary.
9.2. Jagarnath 24.06.1989- 10 killed,it has two quarries namely the “Pilot”
and “Main” quarry.The accident occurred in Pilot quarry which was
located in the “THROUGH” of two strike faults. The mine was operated
by “Dragline”, “Shovel Dumpers”, “Pay loaders” etc. at about 52 m
depth. Priorto accident there was heavy rainfall for 4 days. A pump was
being installed by a contractor who had engaged 13 workers. The Coal
seam was prone to “Spontaneous heating”.
There were divergent views on the reasons of the disaster. They were
killed by large/small sized stone/Burnt coal pieces hitting the persons.
The small pieces of 6 to 8 cm. were thrown to a distance of around
60m. The slide might have been caused by fire, heavy rain, presence
of fault plane, water entering through wide cracks on the surface etc. or
more probably by a combination of all these. It was apprehended that
there was an “WATER GAS EXPLOSION”( a mixture consisting mostly
of H2 and CO). Another reason as mentioned by the “Court of Inquiry”
was the possibility of generation of superheated steam at high
pressure. “The court of enquiry” over ruled the possibility of “Water gas
explosion” by mentioning that such explosion cannot cause a throw of
1.5 kg clinker to a distance of 130m. “WHOA-WHOA” sound was heard
immediately after the incident supporting the possibility of generation
of superheated steam.
The facts remain that the actual reason could not be established. It
was a unique DISASTER in open cast mines.
9.3. Central Saunda (C.C.L),15.06.2005-14 lives.
In this very mine there was an Inundation on 16.09.1976 causing
death of 10 persons. The disaster on 15.06.2006 is a mix of Air blast
followed by an Inundation. The detail will be explained through “Plan”
and “Section”.
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