MINING METHOD

Dangers in blasting in hot strata                          * Danger of   premature blasting of explosives. *Danger of misfire                          Precautions : DGMS permission shall be obtained.Only slurry or emulsion shall be used. Blasting shall be done with detonating fuse down the hole, Detonator shall not be placed in the hole. Temperature at bottom of blast holes shall be measured and recorded after drilling and every shift thereafter .If temperature of hole exceeds 80° C,it shall not be charged.All holes shall be kept filled with water.A hole traversed by cracks and fissures shall not be charged unless it is lined with an asbestos pipe and the hole filled with water.In addition,bentonite shall be used for sealing cracks at the bottom of holes. Before loading explosives,the detonating fuse shall be cut from the reel.Stemming shall be commenced...

METHOD OF SUPPORTING WEAK SHALE ROOF                  When shale roof can be supported by special type of roof stitching recently designed by CMRI, Dhanbad.Two holes 1.5m deep shall be drilled on two sides at the roof level at an angel of 45° using ordinary coal drills.Three more holes of the same depth shall be drilled vertically in the roof at equal intervals in the same alignment.A piece of old haulage rope 20-22mm dia shall be cut with a length=depth of two holes+width of gallery.One end of the rope shall be fixed in one of the side holes with cement   grout and a wooden plug shall be hammered to prevent the rope shall be fixed in corresponding inclined hole with the cement grout.Now there j-bolts shall be fixed with cement capsule and wooden plugs in the three vertical holes.While fixing j-bolts,there lower end shall be anchored to the rope.When cement is set, wooden sleepers shall be placed between two adjacent rope as ...

  After a slice or stook has been extracted,stowing shall be done as soon as possible.The entire area shall be stowed,no gaps shall be left.Stowing shall be tight upto the roof.As stowing progresses,only one stowing pipe shall be opened at a time.The pipe shall be kept supported and it's end shall not be allowed to get buried in sand.At the end a flexible hose shall be used to fill gaps near the roof.If work is done by level slicing,at intervals barricades of half height shall be erected.Boxing shall be made strong so that it does not burst.Frequent starting/stopping shall be avoided.Stowing Shall be commenced only after ensuring adequate stock of sand and water in the sand bunker,water tank respectively. Support shall be withdrawn timely and any odd material lying inside the boxing shall be removed.Proper arrangment shall be made for drainage of stowing water.Pipe range shall be cleaned by runing only water for 5-7minutes at the beginning and end of stowing.Goad edge shall be kept...

Pneumoconiosis - This is a lung discase caused by inhalation of coal dust laden air over long periods of time(Some years) When a man breathes dusty air, coal dust particles coarser than 7 micron size(1 micron =1/1000mm)are held up in the upper respiratory tract but various percentage of particles of other sizes reach the lung.Some of these cling to the lung surface forming nodules and render some area inactive.On repeated inhalation in such air over extend periods of time,more and more area is involved,causing shortness of breath and weakness.Grandually the man loses total energy to work.It renders the man prone to bronchitis and T.B.also. So far no satisfactory cure of this disease could be found.Hence the only option is prevention.As per the Mines Rules mine workers are subjected to initial and periodic (5years)medical examination,and the X-ray plates are checked to detect the disease in early stage.If necessary his work place is changed to limit the exposure to dust.Under the Mi...

  In any Under ground coal mine,even at normal temperature some oxidation of coal takes place.In this process,some O2 is consumed and CO is produced.The ratio CO produced/O2 consumed,known as Graham's Ratio or Graham's Index,for a mine remains more or less constant.If spontaneous heating occurs there is steady rise of the ratio with increase of temperature.The ratio can,therefore be used as a guide to detect heating.     Regulation prescribe that the return air of every depillaring distt.Shall be analysed at least once in every 30days to determine the Graham's Ratio.If successive tests show steady increase in the ratio,steps shall be taken to determine the site of heating and to deal with it.      Incubation period : This is the period between the time when coal is first subjected to condition favourable for heating develop when the first Major roof fall occurs, because fallen/Crushed coal starts heating but the heat does not escape as coal...