The lignite seam was first exposed in August 1961 and regular mining of lignite commenced in May 1962. German excavation technology in open cast mining, using Bucket Wheel Excavators, Conveyors and Spreaders were used for the first time in the country in Neyveli Mine-I. The capacity of this mine was 6.5 MT which met the fuel requirement of TS-I. The capacity was increased to 10.5MT of lignite per annum from March 2003 under Mine-I expansion scheme and at present meets the fuel requirement for generating power from TPS-I and TPS-I Expansion.
MINE - II:
In February, 1978 Government of India sanctioned the Second Lignite Mine of capacity 4.7 MT of lignite per annum and in February `83, Government of India sanctioned the expansion of Second Mine capacity from 4.7 Million Tonnes to 10.5 Million Tonnes. Unlike Mine-I, Mine-II had to face problems in the excavation of sticky clayey soil during initial stage. The method of mining and equipment used are similar to that of Mine-I. The seam is the same as of Mine-I and is contiguous to it. The lignite seam in Mine-II was first exposed in September 1984 and the excavation of lignite commenced in March, 1985.
GOI sanctioned the expansion of Mine-II from 10.5 MTPA to 15.0 MTPA of lignite in October 2004 with a cost of Rs. 2295.93 crore. Mine-II Expansion project was completed on 12th March 2010. The lignite excavated from Mine-II meets the fuel requirements of Thermal Power Station-II and Thermal Power Station–II Expansion under implementation.
Government of India sanctioned the project Mine-I A of 3 million tonnes of lignite per annum at a sanctioned cost of Rs. 1032.81 crores in February'98. This project is mainly to meet the lignite requirement of M/s ST-CMS for their power plant and also to utilize the balance lignite to the best commercial advantage of NLC. The project was completed on 30th March 2003 within time and cost schedule.
GOI sanctioned implementation of Barsingsar mine with a capacity of 2.1 MTPA of lignite per annum at an estimated cost of Rs. 254.60 crore in December 2004. Both overburden and lignite production has been outsourced. Lignite excavation commenced on 23rd November 2009 and production attained the rated capacity on 31st January 2010.
UNIQUE FEATURES OF NEYVELI LIGNITE MINES
A. Occurrence of Ground Water Aquifer below lignite Bed :
A huge reservoir of ground water occurs below the entire lignite bed, exerting an upward pressure of 6 to 8 kg/cm2. Unless this water pressure is reduced before mining, it will burst the lignite seam and flood the Mines. This problem was overcome by continuously pumping out water round the clock through borewells located at predetermined points and thereby reducing the water pressure at the lignite excavation area. Over the years, through continuous study and implementation of new methods, the quantity of water pumped out has been reduced from 50,000 GPM to 32,000 GPM. (For mining one tonne of lignite, about 13 tonnes of water has to be pumped out). The water level is continuously monitored through observation wells for proper ground water management.
B. Higher Ratio of Overburden to Lignite :
The overburden to lignite ratio at Neyveli Mine-I is 5.5 to 5 M3: 1 tonne. This requires huge quantity of overburden to be removed (11 T. of overburden is to be removed for mining 1 tonne of lignite). High capacity excavators are used for handling large volume of overburden, after forward preparation.
C. Hard overburden strata :
The highly consolidated overburden stratum consists mainly of Cuddalore sandstone and is hard and abrasive in nature. This problem was overcome by carrying out suitable modifications in the bucket wheel teeth and by instituting a systematic drilling and blasting programme.
D. Cyclonic area :
The Mine is located in a predominantly monsoonic and cyclonic area. The average rainfall in a year comes to about 1200 mm and the wind velocity goes upto 160 KM per hour. Every year, an Action Plan for monsoon is prepared well in advance in detail.