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Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
Extraction of developed pillars.doc1
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Extraction of developed pillars.doc1

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  • 1. Tikeshwar Mahto, Dy. Dirctor Mines Safety, Bilaspur Region tikeshwarmahto@yahoo.co.in SAFE EXTRACTION OF DEVELOPED PILLARS BY OPENCAST METHOD – A CHALLENGE FOR MINING ENGINEERS : A Case Study ABSTRACT Dependency of our energy requirement on coal in future will still continue till the technology advancement in the field of renewable energy. Presently 60% of the total energy demand is fulfilled by coal. The coal production of country in the financial year 2012-13 is around 557 Mt. The share of opencast mines is more than 70%. Opencast mines are shrinking day by day due to exhaustion of virgin coal. Extraction of coal by Underground mining is very uneconomical. In future there will not be any virgin coal seam for opencast mining and only alternative for coal production will be by open casting of developed pillars of underground mines. There are nearly 3 to 3.5 BT of coal reserves in standing pillars in the country. In SCCL there are 15 open opencast mines and mostly working on developed pillars of old underground mines. Upcoming opencast projects are being planned on old underground mines. And future of mining engineers will be very- very challenging. In this paper the author is expressing his experience about the challenge to extract the coal from the underground developed pillars. Introduction The author has worked in RG OCP-I, a big opencast mine (5Mt) of SCCL, running on old developed pillars and goved out areas of GDK. NO.-9 Incline & GDK.NO.- 10 Incline Mines. The mine is having a Dragline, Rope Shovels & 12 Cum Hydraulic Shovels (Diesel version). Dip side of the underground mines are separated from rise side workings by constructing dams and underground mines are running still on dip side of the property by making alternative approaches. Standing pillars & goaved out areas in Rise side of the old underground mines are being worked by opencast method. Working in this mine is challengeable as far as ground control & fire are concerned. Extraction of Developed Pillars by Opencast Mining Extraction of U/G developed pillars by opencast method is very challengeable for mining engineers. Blasting operation on developed pillars is very critical activity of the mining operation. There are chances of Premature detonation of explosives in fiery holes, if proper precautions are not observed. Such type of accidents have already occurred in opencast mines operating on underground developed pillars. There is history of Coal dust explosion due to blown through shots. Pot holing is also a notorious name in underground converted opencast mines. Earlier in a mine accident, one Assistant manager fell in a pot hole having active fire and couldn’t be recovered. Recently in an opencast mine a 1
  • 2. Dumper operator jumped from the dumper after seeing heavy inrush of smoke from a pot hole in front of dumper and fell into the pot hole and died instantly. DGMS Circulars issued time to time regarding extraction of developed pillars 1. Precaution against danger of coal dust explosion while extracting pillars by opencast method (Cir. Tech. 4/1980)-Attention is invited to DGMS (Tech) Circular No. 11/1979 in which it was stipulated that LOX shall not be used for blasting in overburden within 15m of the underground workings in the coal seams immediately below or in the vicinity. It was also suggested that: No shot hole shall be drilled in O/B above underground galleries.  A parting of at least 3m between the bottom of a shot hole and the coal seam shall be left intact. The above precautions have to be observed not only with LOX but With all other types of explosives used in opencast mines. After were to be • a coal dust explosion in an opencast mine, the previous guidelines elaborated to prevent a recurrence of the accident. The Precautions taken in this connection are listed belowSurvey, Cleaning and dusting: Where the U/G workings are accessible, the same shall be surveyed and cleaned of all coal dust and thickly stone dusted before commencement of extraction of pillars. • Withdrawal : All persons from U/G in the same workings seam or any other seam or section connected therewith shall be withdrawn before commencement of blasting operations in the quarry and the work persons shall not be permitted into the said U/G workings unless and until the same have been inspected by a competent person OR The U/G workings to be quarried shall be isolated by explosion proof stoppings or by any other approved manner from any active working area either in the same seam or different seam or section as the case may be, so as to prevent transference of danger to the said working areas. • Location of holes: The spacing of holes in the bench lying immediately above the coal seam (referred to hereinafter as last OB bench) shall be so adjusted that the holes do not lie immediately above the galleries as far as possible in order to ensure that the blast holes do not directly fire into the U/G workings. • Safe parting: The depth of the hole in the last OB bench shall be such as to leave at least 3.0 m thickness of OB above the coal seam, and to ensure compliance with this requirement a pilot hole be put for each round of blasting to determine the total thickness of OB over the coal seam. 2
  • 3. NOTE: - This condition has been modified in subsequent DGMS Circular, which is as follows?  No person or machinery shall be deployed or permitted to be deployed in any portion of the quarry lying over U/G galleries, free from water, where the thickness of parting is less than 6 m in coal or 4 m in O/B.  To comply this conditions parting of at least 4 m thick immediately above the developed pillars shall be blasted at once including thickness of coal seam to prevent any sinking of HEMM and persons into any U/G galleries during extraction of coal. • Filling sand in holes: Where there is any doubt and particularly where there is any cracks and crevices, the bottom 2m length of the hole shall be filled with sand. • Delay detonators not to be used: Unless otherwise permitted by DGMS, no delay detonators shall be used in coal and the manner of extraction of pillars shall be by drilling & blasting holes in coal pillars only from top downwards. • Workings developed in more than one section : Where more than one section of the seam had been developed on pillars, the shot holes shall not be drilled 3m of a lower section, and care shall be taken that, as far as possible the blast hole do not directly fire into any U/G gallery. To ensure compliance with requirement, a pilot hole shall be put for each round of blasting. • Use of water ampoules/moist sand: All holes in the last OB bench and/or in coal shall be charged with water ampoules or with moist sand of at least 0.6m in length at the bottom of the hole. • Shelter: No person including shot firer take shelter within 100m of the quarry openings, and such shelter shall be of an approved design. • Administrative control: The opencast working over U/G part of working shall be under the administrative and technical direction and control of the Manager and Agent. 2. Blasting in Fire areas (Cir.Tech.2/1985 & 2/1990): A number of fires are known to be active in different Coalfields. Any attempt to win coal from these areas involving blasting is fraught with danger. In a major accident, 6 persons were killed when a NG- based explosives was being used in an opencast coal mine where fire existed. Some trial were carried out by R&D wing of DGMS in collaboration with CMPDIL and CMRS in extraction of coal from fiery opencast mine and recommended the following precautionary measures:3
  • 4.  (a) No explosives other than slurry and emulsion explosives shall be used. (b) Blasting shall be done with detonating fuse down the hole.  Temperature inside the blast holes shall be measured (before filling with water) and, if the temperature exceeds 800c, in hole, such hole shall not be charged. Records of measurements of temp. in each hole shall be maintained in a bound paged book.  All blast holes shall be kept filled with water. When any hole is traversed by cracks or fissures, such hole shall not be charged unless it is lined with asbestos pipe and the hole filled with water. In addition, bentonite should be used for sealing any cracks at the bottom of the holes.  Detonating fuse shall not be laid on hot ground without taking suitable precautions, which will prevent it from coming in contact with hot strata.  The charging and firing of the holes in any one round shall be completed expeditiously and in any case within 2 hours.  Blasting operations shall be carried out under the direct supervision of an Assistant manager. It is however, clarified that permission/relaxation under different regulations, which may be applicable (e.g. using more than one type of explosives etc.) shall invariably be obtained before carrying out blasting operations. 3. Firing of shots in fire areas/in vicinity of hot strata in opencast Coal mines [DGMS (Tech) Circular 4/2006]:Recently, in a mechanized opencast coal mine, where extraction of developed pillars by deep hole blasting was being carried out, one of the shot hole left charged, prematurely detonated after a lapse of two and half hours. Fortunately no person was involved as the holes were unstemmed and there was no one in the vicinity. The following additional precautionary measures shall be taken over and above the measures stipulated vide DGMS (Tech.) circular 2/1985.  The blasting officer shall ensure accurate measurement of temperature at bottom of the shot holes drilled in coal benches and in O/B benches immediately above the coal seam and other fiery areas to determine whether fire exists. The measurement shall be recorded in a bound paged book kept for the purpose. For this purpose the temperature shall be measured initially after completion of the hole and thereafter at least once every shift. No hole shall be charged, if the temp. in the hole exceeds 800C.  As a precaution against presence of pocket fires in coal benches in developed seams, O/B benches immediately above the coal seams and other fiery areas in the mine, the explosives charged shall be fired by detonator attached to the detonating cord at the surface and not within the shot hole.  All explosives, cast boosters, detonators, detonating cord and shock tubes shall be subjected to proper testing in an approved laboratory in 4
  • 5. respect of temperature sensitivity and impact sensitivity for safe handling in mines. A certification to that effect shall be supplied for each batch.  Sleeping of holes shall not be permitted in coal benches, where fire or Spontaneous heating has been detected and in O/B benches lying immediately above such seam and at all places where there is likelihood of fire or Sp. Heating.  No PETN/TNT based cast booster shall be used for initiating non- cap sensitive slurry/emulsion explosives in coal benches and O/B benches of a fiery coal seam. Processes before starting extraction of developed pillars by Opencast methods are as follows: • • • • The U/G workings to be quarried shall be isolated by explosion proof stoppings or by any other approved manner from any active working area either in the same seam or different seam or section as the case may be, so as to prevent transference of danger to the said workings area. Before intended to close the U/G mine for conversion to O/C, a detailed off set survey has to be conducted by using latest survey equipments like Total Station etc. and the position of workings including the disturbances and falls should be clearly demarcated on the plan.. The U/G mine Manager should see that the plan prepared for handing over to Opencast mine manager is flawless, because once the U/G mine is abandoned, the O/C operation becomes blind folded and only guidelines remains with the O/C management is U/G plan submitted by the surveyor of U/G Mine. It should clearly picturise the each and every detail of U/G workings. Cleaning of all coal dust and thick stone dusting before commencement of extraction of pillars. Retaining of key personnel of U/G mine, like Surveyor, Overmen and Officers for safe and effective operation of O/C mine. After completion of all legal and statutory formalities, the mine is developed as per the permission conditions of DGMS. For safe and systematic excavation, the mine is divided into four zones viz. A. SAFE ZONE. B. CRITICAL ZONE C. DANGER ZONE AND; D. COMPACTED ZONE (A) SAFE ZONE: It is the zone of safety, where the parting is over U/G galleries is more than 15m. In this zone all activities can be carried out and the zone is to be demarcated with `White` flags. (B) CRITICAL ZONE: It is the zone, where proper precautions are required for 5
  • 6. excavation. In this zone, the parting of working O/B benches over U/G galleries is more than 4m and less than 15m. Whenever, the plan parting reaches 15m to u/g galleries, further reduction shall not be done unless it is proved physically. After proving the physical parting, further parting is reduced to 4m hard O/B. In this zone the excavation is done by Back hoe shovel in level loading. This zone is demarcated with `Yellow` flags. (C) DANGER ZONE: Danger zone means, the area where the parting over U/G galleries is 4m hard O/B or less. No work shall be done in this zone except dozing and drilling for compaction. The dozing and drilling shall be done under proper supervision. Danger zone is to be demarcated with `Red` flags. (D) COMPACTED ZONE: When danger zone is converted to safe zone by Compacting the U/G galleries by drilling and blasting (4m O/B and coal seam combindely), it is termed as `Compacted` zone. This zone is permitted for normal extraction of coal/OB, as it is safe. It is demarcated with White flags. Note: As per DGMS guideline, the extraction of O/B in Critical zone should be done upto 4m parting over galleries, but 4m hard O/B parting is not safe for running HEMM and formation of pot- hole can’t be avoided. Hence for extra precaution, Critical zone is assumed between 6-15m. When the working in critical zone reaches to 6m, it is treated as danger zone. Safe Zone 18m Critical Zone 15m 12m Danger Zone O/B Compacted Zone 6m Coal Seam with Developed galleries O/B Parting over the Galleries in different zones Fig: 1 6
  • 7. Working in different zones: I. Whenever the area reaches to critical zone as per plan parting observed by the Surveyor, test holes shall be drilled at demarcated places to prove the physical parting. The critical area is demarcated with `Yellow` flags. II. Based on the proved parting, O/B benches shall be lowered upto danger zone. III. Whenever the area reaches to danger zone, the area will be leveled for drilling under proper supervision. Then the surveyor will mark the position of U/G galleries and drill hole pattern on the benches with stone dust as per the approved plan. The surveyor will display the play cards at the junctions mentioning the place and plan parting on it. IV. The Surveyor will hand over the notice of the galleries and parting with sketch to the Overman, Under Manager, Blasting In-charge, General shift In-charge and to the Manager of the mine, before operating in Critical and danger zone. V. General shift In-charge will give the necessary instruction in writing to the concerned Shift persons regarding drilling and extraction in critical and danger zone. VI. Test holes shall be drilled to ascertain the parting before commencement of actual drilling operation. VII. Based on the above test hole report, the termination of holes over the galleries will be ascertained. In O/B, the holes above the galleries shall be terminated 1.5- 2m before touching the galleries and in coal 2-3m for providing proper confinement of explosives column around the holes and to avoid blown through shots in the galleries. VIII. The drilling on pillars and galleries shall be done as per the pattern shown in the sketch provided by the Surveyor and under the supervision of an Overman. IX. The Overman and Under Manager In-charge will record the proved partings and pattern of drilling with depths and will be kept for the purpose. Compaction of Galleries a critical activity of the U/G converted Open cast mine: When the operation of the mine falls in the danger zone (i.e. parting over galleries is less than 6.0m), it needs careful progress to expose the developed coal seam. As per DGMS guideline, at least 4m thick O/B parting (here 6m) immediately above the developed galleries shall be blasted at once including thickness of coal seam to prevent any sinking of HEMM and persons in to the U/G galleries during extraction of coal. Here, 7
  • 8. O/B and coal are blasted simultaneously by drilling holes from O/B to floor of the galleries in coal to compact the galleries is called combined blasting. (A)Drilling pattern for combined blasting when the galleries are developed in single section: F R E E A A` F A C E O/B Coal Seam with Developed galleries Section along A –A` showing depth of holes on pillars & galleries 8
  • 9. (B) Drilling pattern for combined blasting when the galleries are developed in two sections with superimposed galleries: F R E E A A` F A C E O/B Coal Seam with Developed galleries 9
  • 10. Section along A –A` showing depth of holes on pillars & galleries Fig: 2 (C) Drilling pattern for combined blasting when the galleries are developed in two sections and parting between two sections is more than 6 mtrs: If the parting between two sections is more than 6 mtrs, the combined drilling & blasting should not be done in the fashion as shown in the Fig.2. The author has experienced that, if the combined blasting is done in the fashion as shown in Fig.2, there is coal loss of around 10-20% in the form of contamination. The economical aspect is also taken into account in addition to safety factor. DGMS has permitted to maintain minimum parting of 6m in coal or 4m in O/B. Therefore, combined blasting can be done separately for both the sections, when the parting between the two sections is nowhere less than 6 mtrs. First combined blasting is done in 6m (O/B) and 3m Coal (i.e upto the bottom of the top section gallery). After exposure of Coal, the above procedure is repeated separately for gallery compaction in bottom section. The exposed coal is leveled with dozer and demarcation of bottom section galleries is made with stone dust. Drill is engaged under proper supervision to test the parting of bottom section gallery. Then pattern of drill holes are marked for drilling & blasting. After blasting in coal, again it is compacted with dozer before lifting the coal. The drilling & blasting pattern in both the sections separately are shown in figure below. O/B Parting between two sections is more than 6mtrs Fig.3 10
  • 11. Section along A –A` showing depth of holes for compacting only top section galleries Exposed Coal O/B Fig.4 Section along A –A` showing depth of holes for compacting bottom section galleries in coal after exposure. Another disadvantage of combined blasting at a time of both sections is fire. When full depth of coal is blasted combindely and left for few days, the fire spreads more rapidly throughout the depth of coal due to more area of contact with air and some times it becomes very difficult to control the fire. (D) Drilling pattern for combined blasting when the galleries are developed in two sections and both the sections are not superimposed (i.e. staggered ): When the galleries are staggered and parting between two sections is less than 6m, then drilling & blasting activities become very critical. The author has applied many trial and error techniques and finally established a system, which is being continued in the mine. Both the galleries are marked with different colours. Top section gallery with white stone dust and Bottom section with black coal dust, so that we can easily distinguish both the sections. Then holes marking are done with reference to the top section gallery. Only care is taken that the drill holes, which are close to the bottom section gallery, are terminated 3m before touching the gallery and remaining holes are drilled upto floor of the bottom section gallery as shown below.. 11
  • 12. O/B Parting between two sections is Less than 6mtrs with staggered gallery Fig.5 Section along A –A` showing depth of holes for compacting both galleries when parting is less than 6m. (E) Drilling pattern for combined blasting when the galleries are developed in two sections with parting more than 6m, in the intention to reduce the number of holes for making charging and blasting comfortable on the same day: 12
  • 13. B F R E E A A` F A C E B` Fig.6 O/B Coal Seam with Developed galleries Section along A –A` showing depth of holes on pillars & galleries for compacting top section galleries. 13
  • 14. Fig:7 1.5- 2,0m Above the gallery O/B D I P Section along B –B` shown in fig:6 in Strike direction, showing depth of holes on pillars & galleries Fig:8 When the O/B bench immediate to the galleries is tested and declared for danger zone, a stringent care should be taken till the compaction of galleries. A First class Certificate holder should be the In-charge of the compaction of galleries. He will monitor everything starting from drilling to compaction of the galleries. Precautions while drilling over galleries: o Code of Practice shall be framed and implemented before starting the extraction in the mine and following will be the salient features: a) While marching the drill, it should not be marched over the U/G galleries. b) Drill should not be marched over the gallery junctions. c) Drilling should be carried out by placing the drill over the pillar. d) Whenever any hole is inadvertently punctured into the gallery a fresh hole shall be drilled 1.0 m adjacent to the hole. 14
  • 15. o After leveling the danger area carefully by an experienced Dozer operator, the position of the junctions and galleries edges shall be marked with play cards and stone dust respectively by the Surveyor. Play cards will show the Plan parting. o The In-charge for galleries compaction will arrange drill under personal supervision of an Overman to prove physically the parting over the galleries. After proving physical parting, the Surveyor will circulate the report to all officers and supervisors and the same will be recorded for compliance of the statute. As per the physical parting report, drilling pattern shall be decided. o If the galleries are developed in single lift and the depth of hole on pillar is less than 10m, a drill of 150 mm diameter is adequate to compact the galleries. But, if the galleries are developed in double lifts (Top & Bottom), the depth of the hole on pillar will be more than 20m. For this, small diameter (150mm) drill will not be capable to compact the galleries perfectly. For this purpose, larger drill of diameter 250mm will be required. o If 250mm dia. Drill is used for drilling over the gallery, as shown in Fig. 1,2 &3, single row is sufficient to collapse the gallery. But, in case of drill of 150mm dia, two rows will be required. 4m For 250mm drill 4m 2m For 150mm drill o Holes over the galleries shall be terminated 1.5m – 2.0 m before touching the gallery and this will be decided on the basis of test holes report, drilled at junctions and galleries. o A survey person shall be deployed, while drilling on galleries and pillars to guide the drill operator and record the depth of the holes as per the hand sketch prepared by the Surveyor. o Holes on the pillars shall be drilled upto floor of the gallery (in case of two sections, the holes should touch the floor of the bottom section gallery as shown in Fig.2 &3). 15
  • 16. o Pattern of holes on pillars:  For 10 m hole depth, the burden & spacing pattern shall be 5m X 6m for 150mm diameter drill and 6m X 7m for 250mm diameter drill  For 10m – 15m hole depth, the pattern of burden & spacing shall be 6m X 8m for 250mm diameter drill.  For more than 15m depth of the hole, the burden & spacing pattern shall be 7m X 9m for 250mm diameter drill.  The distance between first line of holes and edge of the gallery should be 2.5 to 3.0m, as shown below; D I P 2.5- 3.0 m FREE FACE Charging & Blasting operation: • After completion of drilling, Blasting In-charge shall inspect the area and shall make estimation of explosives required on the basis of depth of holes. As far as possible, the drilled holes shall not be left for long time to avoid catching fire. As per DGMS circular mentioned above, no slurry or emulsion explosives shall be used in fiery holes and we can’t avoid fire in holes drilled for combined blasting purpose. Hence, only LDC explosives with detonating Cord shall be used for blasting to compact the galleries. • Temperature of the holes shall be measured with Infrared based thermometer and if it exceeds 80 0C, the charging shall be stopped. Charging and blasting in fiery holes shall be done as per the DGMS circular Tech.2/1985 & 2/1990 mentioned above. 16
  • 17. • Charging of holes on pillars :  If the galleries are developed in single lift in Top section of the Seam as shown in Fig. 1, the depth of holes on pillars shall be in range of 9m to 13m, in which O/B parting will be 6m to 10m and 3m coal (upto gallery height). Charge columns in O/B and Coal shall be separated by a Deck of 2-3 m height. Stemming in OB (3- 3.5m) OB (6-10m) Charge column in OB (2.- 5m) Deck column (2.5 - 3m) Coal (3m) Charge column in Coal (1.5m) Charging pattern of 150mm diameter hole Explosives charge in Coal = 31.25 Kgs.(four Cartridges, each of 6.25 Kgs) Explosives charge in OB = 62.50 to 93.75 Kgs. Total charge in a hole = 93.75 to 125 Kgs  If the galleries are developed in single lift in Bottom or Middle section of the Seam and Coal parting above the galleries is more than 6m, then combined Blasting is not required. Coal will be exposed in a normal way and after exposure of coal seam; total thickness of coal will be blasted at a time taking all necessary precautions narrated above. Only extra precaution to be taken is that, the advance test holes at junctions shall be drilled in OB benches to know the coal parting above the galleries.  If the galleries are developed in double lifts or sections as shown in Fig. 2 & 3, the depth of holes on pillars shall vary as per the thickness of coal seam. Let us assume that, the thickness of coal seam is 16m, then depth of holes on pillars will be in the range of 22 to 26m, because OB parting will increase along Dip direction. 17
  • 18. Stemming column in OB( 3 - 4m) OB (6 to 10 Charge column in OB (2- 5m) Decking in Coal & OB (3m) T/S Charge column in Coal (5m) C O (16m) A L Decking in Coal (4m) Charge column in Coal (5m) B/S Charging pattern of 250mm diameter hole Explosives charge in Coal In Ist Deck In IInd Deck Explosives charge in OB = 250 Kgs. (LDC each of 6.25 Kgs) = 250 Kgs = 100 to 250 Kgs. Total charge in a hole = 600 to 750Kgs. If the total number of holes on pillars is 32 (16 on rise side and 16 on dip side), as shown in Fig.3, the amount of explosives required is = 600 X16 Kgs + 750 X 16 Kgs =9600 Kgs + 12000 Kgs = 21600 Kgs  Charging of holes on Galleries: Parting above gallery in OB varies between 6- 10 m. Hence, depth of the holes above the gallery in OB will be 4- 8m, term inating the hole 2m before puncturing into the gallery. The amount of explosives required will be 62.5 Kgs to 125 Kgs. 18
  • 19. If, the total number of holes above the galleries in OB is around 23(10 in dip side and 13 in rise side), as shown in Fig.3. Then the total amount of explosives required will be = 62.5X13 Kgs + 125 X 10 Kgs = 812.5 + 1250 Kgs = 2062.5 Kgs. Hence, total amount of explosives for on one round of blasting is = 21600 +2062.5 =23662.5Kgs. So, in one round of blasting 23-24 tonns of explosives is required. Compaction of gallery after blasting: Immediately after blasting, a dozer (minimum of 355 H.P.) with experience operator shall be engaged under proper supervision for leveling & compaction of the blasted galleries. After proper compaction, the area will be marked with `White` flags to treat as safe zone for extraction. Precautions while extracting in compacted zone: After proper compaction of the area, again gallery and junction shall be marked with stone dust and with`White` flags. Also a limit line shall be marked for the excavation. Excavation will be done under personal supervision of an Overman. Coal should not be left exposed for long time. After exposure of coal, it should be dispatched immediately; otherwise a serious risk of fire will be created. Precaution against fire: Spontaneous heating & Fire is a common phenomena in the Opencast Mine excavating the developed pillars. If the fire is not handled properly, it will create a serious problem to health of human beings and the environment. To control the fire in the exposed galleries, following arrangements shall be made in advance and with the progress of the excavation.  The blasted galleries shall not be kept exposed unnecessarily.  Fire fighting ranges (water pipe lines) shall be laid in an advance in de-coaled area along the strike direction and it will be shifted as per the movement of the extraction.  High pressure water Jets shall be used for quenching the fire and flames arising from coal bench.  If fire is not controlled by water spraying, it shall be completely blanketed with O/B or dispatched immediately after wetting with water. 19
  • 20. SAFETY EDUCATION AND PROPAGANDA: Safety education is very important for making awareness to all workmen, Supervisors and Executives regarding the danger associated with the extraction of developed pillars and precautions to be taken while operating HEMM and other equipments. Recently, in one Opencast Mine, one dumper Operator jumped from the dumper by seeing heavy inrush of smoke in front of dumper and fell into the pot hole and died. If, he had well trained regarding the danger with pot hole and precautions to be taken while working on the gallery, he could have saved his life. He could not differentiate, whether the smoke arising in front of dumper was due to the fire in dumper engine or it was blowing out of Pot- hole formed with tyre of the dumper. Here, in author’s view a special training program should be arranged for all workmen and supervisors at VTC. Every month, In-charge for compacting galleries will conduct a safety meeting on gallery compaction and danger with the operation. Suggestions will be invited from the supervisors/ executives and workmen. All the minutes shall be recorded in a bound paged book kept for the purpose. Conclusion To avoid collapsing of under ground galleries and bogging down of men and machinery, effective compaction of galleries will be done to extract coal from standing pillars by opencast method. Surveying is very- very important in U/G turned O/C mine. The plan submitted by the U/G mine manager should be very handy and informatic. Surveying should be conducted with latest instrument like, Total Station etc. A dynamic leader and enthusiastic team work is required to take all these challenges smartly. Declaration All the observations and comments made by the author in this paper are personnel and not necessarily to the organization. Date 26-1-2014 Tikeshwar Mahto Dy.Director of Mines Safety, Bilaspur Region 07898033693 Email – tikeshwarmahto@yahoo.co.in 20

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