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This article provides general information about the Ravindrakhani New Tech Inc. mine, including its location, opening date, number of seams, and targeted production. It also discusses the events leading up to a fire occurrence and the measures taken to deal with it.
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General Information about the Mine • Name of the mine : Ravindrakhani New Tech Inc • Location of the mine : Mine is situated 14kms from Manchiryal Rly. Stn inAdilabad,Dist,(A.P) • Opening of the Mine : 19-10-1983 • No.of Seams : 2 (No.1A, 1 seam) • Parting between both :16 mtrs to 20 mtrs. • Seams • Average Gradient : 1 in 4.2 • Mine take Area : 344 Ha. • Targeted Productin :4.62 Lakh Tonnes. • Worked out panels by Caving :1A-N1,1A-N2,1A-1,1A-2,1A-3,1A-4 :1-N1,1-N2,1S-1,1S-2,1S-3 • Working districts : 1A-6,1A-5,1S-6, 1S4 caving depillaring panels. Contd..
About the mine • 8 SDL’s were worked with pony belt conveyor system in 4 depillaring caving panels. • Men on roll of the mine was 1622 • The mine was provided with Chair Lift Man riding system from surface to 39 L/1A seam for a distance of 1.16KMs.
Works engaged on playday in I Shift (13.07.2008) • Gear box drain plugs and Gear oil changing work to S8 SDL at 1S6 panel. (Welding work Engaged) • Track roller changing work to S5 SDL at 1A6 panel. (Welding work Engaged) • Cable changing work to S3 SDL at 1A6 panel. • 3 Lakh fan and 150 HP hauler maintenance • Hauler Rope re-coiling work at 1AS/33R
Events prior to the occurrence of fire : • In 1A-6 panel in 31 LN gallery S5 SDL right traction rollers replacement was arranged. They have completed the gas welding work by 11.30am, stopped the work at 1.30pm and came to surface by 2.20 pm. This work was done by Sri. Sadaiah, Fitter with the help of gas cutting by Sri SIAA Saleem, Welder. • In 1A-6 31A LN gallery trailing cable changing work was done for S-3 SDL by 1.45 PM, by Sri Venkatrajam, Electrician with his crew. • In 1S-6 panel S-8 SDL oil filling in traction gear box was done by Sri Vijaya Rama Rao, Fitter and SDL Canopy welding work has carried out by Sri Venugopal Raju, welder with his crew. completed the work at about 11:15am
Events prior to the occurrence of fire : • In panel 1S-4 for S-7 SDL restoration of remote control work was done by 12:30 pm. • After the completion of cable changing work at 31 A LN /34 dip it is reported that they were coming up along 33 dip and they reported that some smoke was noticed in 30 LN/33 dip. It is also reported that traction rollers changing work was completed by 1.30 pm. This crew has observed smoke coming from in bye of the 36 dip/ 31L, they have escaped along 31 level along belt section.
Chronology of Events prior to the occurrence of fire : • 12.30 PMFan operator observed the smell. • 1.10 PMFan stopped by Sri V. Venkata Rao, Electrician for planned repairs of MOCB, at RK-NT sub-station by work shop. • 2.15PMPower restored. • 2.20 PM Fan started • black smoke noticed • 2.50 PM All persons were removed from Under Ground.
Rescue Events in Initial Hours • 3.30PMIncharge MRS, MM, Supt. MRS, RG have reached to the spot. • 5.05 PM Rescue team collected Samples from Fan Evasee • 6.00 PM Rescue team inspected main return at 3L/1A Seam, CO found 1200 ppm and main return 0L/1Seam, CO found more than 2000. • 6.00 PM Established control room on surface at RKNT. • 8.40 PM Two rescue teams proceeded to Underground to short circuit the 1A seam & 1Seam. ventilation circuit. Samples collected from 1Seam & 1A seam. observed dense smoke and CO more than 2000 ppm • 8.50 PM Decision was taken to seal off the Mine entries
Closure of Mine Entries • 9.00PM to 10.30 PMAir shaft (intake) was temporarily closed. • 11.00PM TO 6.00 AMClosed Manway and Main Incline • 6.05AM300hp Main Fan stopped • 6.15 AM to 11.20AMUpcast Shaft and Down cast Shaft were closed on 14/07/08
Dealing/ Monitoring of Fire • Surface Bore holes(18 Nos) plugging done. • Crack Filling over goaved out panels was done. • Mine air samples not obtained due to negative pressures after closing of mine entries and with establishment of pressure balance chambers (sliding doors with auxiliary fans) at Manway, Main Incline on 18/07/08 and Fan shaft on 21/07/08 and Air samples were collected.
Dealing/ Monitoring of Fire • Surface Bore holes(3 nos) were drilled to 1A Seam and 1Seam for inertisation and monitoring of gas samples. • 372 ( each 7000 lit) nos. of CO2 cylinders were flushed through to surface bore holes and Air shafts. • 10 tonnes of liquid CO2 was flushed through return air shaft. • Air samples were collected from surface bore holes, mine entries and inter seam bore holes from RK-7. • Bore holes temperature was monitored. • Regular inspection and monitoring was done. • All the works were carried out under Rescue cover.
Interpretation of Mine Air samples Interpretation of mine air samples from 14.07.08 to 05.08.08 revealed the fire has died down. Details are as below. • Oxygen was dropped to 0.961% from 17%. • Carbon monoxide was dropped to 0 from 4.440%. • Methane dropped to 0.725% from 1.360%. • Hydrogen was dropped to 0% from 3.180%. • Effective combustibles were dropped to 0.72 from 6.710. • CO/O2 ratio was dropped to 0 from 64. • Effective inert was increased to 99 from 11. • Carbon dioxide was increased to 8 % from 2.3 %. • R value was increased to 1 from 0.1 resulted in reduction of explosive mixture area.
RE-OPENING OF MINE Re-opening of mine is under taken from 06/08/08 and still continuing. The sequences are as below • Initial openings were made at main incline, man way and intake air shaft and ventilation circuit was established with 20HP auxiliary fan and explored the workings up to 4L and air intake air shaft. • Stoppings were built at entries to 1 Seam at main incline, man way and 5L tunnel to cut off air supply to 1 Seam workings. • Opening was made at return air shaft and ventilation circuit was established with 50HP Fan. • Explored return Air shaft in 1A seam and cut off return air ways with temporary stoppings in 1 seam return shaft. • Explored the workings in 1A seam up to 40L including working districts and found normal environmental conditions.
RE-OPENING OF MINE • Explored the 1S 6 panel of 1 seam through 33D tunnel and 31 ½ tunnel. • During the Exploration 1.Roof falls noticed between 18AL to 20 L 2.Cables, belt conveyor and coal burnt in 1S6. 3. 2 SDLs were covered under roof falls in 1S 6. 4. 2 SDLs were drowned in 1S4. 5. Burnt ash was found in 25LN/1S6.
RE-OPENING OF MINE • Isolating of 1S-6 panel from 26L to 13L between 37R and 36R is planned and the stoppings at 26L, 25L, 38R, 37R of 24L,18LN, 14LN, 13LN and 12LN were completed and partially constructed at 23LN/36R. • Due to Intense heat and smoke along 36R further rescue work could not be taken up and decision taken to seal off entire 1 Seam at inter seam tunnels and Up cast shaft below 1 seam. • Accordingly all the entries to 1 seam and Up cast below 1 Seam were closed. • Drilling of up ward bore hole from RK-7 workings to RKNT is under progress for de-watering. • High capacity pumps are being installed for de-watering the mine energizing of the power is under progress.
