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Limestone Mining
Limestone mining can negatively impact the environment in several ways. A case study of limestone mining in the Katni River watershed of Madhya Pradesh, India found that: (1) Opencast limestone mines increased calcium levels and total hardness in groundwater, degrading local water quality beyond standards. (2) Mines located in higher elevation areas caused turbid runoff that polluted downstream areas. (3) Within 11 years, calcium levels in the area increased by over 100% and hardness by over 500% due to limestone mining impacts on groundwater. Strict preventative measures are needed to curb further pollution from mining.
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Limestone Mining
- 1. LIMESTONE MINING Environmental Impact:a case study Submitted by: Amritesh 717MN1023
- 2. Contents ■ INTRODUCTION ■ ENVIRONMENTALIMPACTS OF LIMESTONE MINING ■ CASE STUDY: KATNI RIVERWATERSHED, MADHYA PRADESH ■ REFERENCES
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- 4. What is Limestone? ■Limestone is a sedimentary rock composed mainly of calcium carbonate (CaCO3) in the form of the mineral calcite. ■ The two most important constituents of limestone are calcite and dolomite. ■ Limestone altered by dynamic or contact metamorphism become coarsely crystalline and are referred to as 'marble' and 'crystalline limestone’. ■ The limestone which is used by industries in bulk quantity is a bedded type sedimentary limestone. ■ The dimensional limestone is used for building and ornamental stone.
- 5. Resources and Reservesin India ■ The total reserves/resources of limestone of all categories and grades as per NMI database based on UNFC system as on 2015 has been estimated at 2,03,224 million tonnes, of which 16,336 million tonnes (8%) are placed under Reserves category and 1,86,889 million tonnes (92%) are under Resources category. ■ Karnataka is the leading state having 27% of the total resources followed by Andhra Pradesh & Rajasthan (12% each), Gujarat (10%), Meghalaya (9%), Telangana (8%) and Chhattisgarh & Madhya Pradesh (5% each). Grade-wise, cement grade (Portland) has leading share of about 70% followed by Unclassified grades (12%) and BF grade (7%). The remaining 11% is shared by various other grades.
- 6. Production (in 2017-18) ■The production of limestone in India is recorded at 338.55 million tonnes from 711 reporting mines. ■ About 97% of the total production of limestone was of cement grade and the remaining 3% was of other grades. ■ Rajasthan is the leading producing state accounting for (22%) of the total production of limestone, followed by Madhya Pradesh (13%), Andhra Pradesh & Chhattisgarh (11% each), Karnataka (9%), Telangana (8%), Gujarat (7%) and Tamil Nadu (6%). The remaining 13% is contributed by Maharashtra, Himachal Pradesh, Meghalaya, Odisha, Uttar Pradesh, Assam, Jharkhand, Jammu & Kashmir, Kerala and Bihar.
- 7. Mining method ■ InIndia, limestone mines are worked by opencast method. ■ Some mines have well-laid road-cum-rail routes. ■ The large mines are developed by forming benches in overburden and limestone bed. ■ The face length, width and height of the benches correspond to the mining machinery deployed and production schedule. ■ Heavy earth-moving machinery like 3.3 to 4 m3 capacity hydraulic excavators in combination with 10-35 tonnes dumpers are normally used. ■ Other mines are mainly worked by semi-mechanised and manual opencast mining methods. As per MCDR reports, drilling is done by Jack hammer & Wagon drill and blasting is done byANFO, Slurry explosives, emulsion explosives etc.
- 8. Uses of limestone ■The principal use of limestone is in the Cement Industry. ■ Other important uses are in: 1. Manufacture of quicklime (calcium oxide), slaked lime (calcium hydroxide) and mortar 2. Medicines and Cosmetics. 3. Glass making 4. Suppress methane explosions in underground coal mines 5. In blast furnaces, limestone binds with silica and other impurities and facilitates their removal from iron
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- 10. Groundwater ■ Groundwater qualitycan be affected by quarrying limestone by increasing sediment and accidental spills directly into the aquifers. ■ These contaminants can also include material like oil and gas from mining equipment. ■ Contaminants in ground water move faster through limestone than other types of rocks. ■ Pumping water out of underground mines changes the direction and the amount of groundwater flow. ■ When the operation of a quarry or mine ends, the direct impacts on groundwater quality may decreased but the long-term contamination can persist.
- 11. Subsidence ■ Limestone isoften mined by opencast working. ■ In humid climates, limestone dissolves quickly and is carried away by water. This creates caves which can become weak and collapse. ■ Underground mining of limestone can cause a cascading environmental impact. It can lower the water table, which removes the support of rock that overlies water-filled caverns, which can create sinkholes.
- 12. Habitat Destruction ■ Asrock is removed by quarrying, any cave passages and the habitat it provides are destroyed. ■ Animals that inhabit these areas that are mobile will be able to find new habitats to survive. ■ Those species that have adapted to such deep cave zones will simply perish.
- 13. Dust ■ Dust isone of the most visible impacts associated with limestone quarrying due to the drilling, crushing and screening of the rock. ■ The mine site conditions can affect the impact of dust generated during extraction, including rock properties, moisture, ambient air currents and prevailing winds, and the proximity to population centres. ■ Fugitive dust can escape from trucks traveling on excavation haul roads and from blasting.This airborne dust can travel long distances from a mining site and affect urban and rural residential areas downwind.
- 14. CASE STUDY Limestone miningin Katni river watershed, Madhya Pradesh
- 15. Abstract ■ Katni riverwatershed covering an area of 1480.4 km2, extends between 23° 34' 53" N to 24° 06' 07 " N latitudes and from 80° 10' 29" E to 80° 41' 38" E longitudes. ■ The limestone is of high grade, rich in calcium content and good for extraction of lime. ■ Several small opencast mining activities have developed in this area in past few years. ■ These mines are located in the Pedi plains situated at the foothills of linear ridges along the northern boundary of the watershed. ■ The underlying rocks are soft and permeable therefore the rainwater filled in these opencast mine pits percolates and degrade the ground water quality by increasing the calcium content and total hardness.
- 16. Study Area Madhya Pradesh,the geographic heart of India, extended between latitude 21° 04' and 26° 52' N and 74° 01' and 82° 48' E. Katni district is situated in the east central portion of Madhya Pradesh, surrounded by Jabalpur, Damoh, Panna, Satna and Umaria districts. Katni river is the main river passing through the district, gave the name to the district. Katni river watershed extends from 23° 34' 53" N to 24° 06' 07" N latitudes and from 80° 10' 29"E to 80° 41' 38" E longitudes covering an area of 1480.4 km2. Climate of the study area is sub-tropical and sub humid. The mean annual temperature is 37.8° C with a mean maximum temperature 41.3° C and a mean minimum temperature 12.5°C. The study area enjoys good monsoon rains with an average annual precipitation of 1368 mm.
- 17. Impact on lithologyand geomorphology ■ This area is well known for its limestone which is of very high grade. ■ Most of the limestone quarries are situated in northern part of the study area which is higher in elevation in comparison to the other parts of the watershed. ■ Therefore, during the rainy season the water filled up in these open mining pits percolates downwards an also increases the turbidity of streams originating from these high elevation areas.
- 18. Lithological and geomorphologicalmaps of the study area
- 19. Impact on slopeand drainage ■ Major part of the study area is having level to gentle slope supporting the dendritic drainage pattern. ■ The major stream is Katni river flowing in the central part of the area. It meets Mahanadi river in north west. ■ In Northern part of the area streams are originating from linear ridges of shaly sandstone, limestone with porcellinite which belongs to Vindhyan supergroup. Most of the limestone mine quarries are situated in this area. ■ These streams originate from high slope area and run almost parallel to each other. These streams pass through the limestone belt and the mining pits and carry a huge load of silt with them in rainy season.
- 20. Slope and drainagemap of the study area
- 21. Impact on waterquality ■ In the study area, the water quality data for 72 observation wells in different villages were collected for the period of October – November 1995 and 2006. ■ Analysis of this data reveals that the calcium concentration in the study area was ranging between 11 to 44 mg/l, in the year 1995. In a period of eleven years i.e. in 2006 calcium concentrations in these observation wells increased to the range of 36 to 114 mg/l. ■ Similarly, the total hardness, which was ranging from 24 to 74 mg/l increased to 115 to 500 mg/l. ■ The spatial distribution of calcium concentration indicates that the area near to opencast limestone mines is having higher concentration. ■ The calcium concentration is above the desired limit in almost entire study area, whereas total hardness is above the desirable limit of Indian standards in almost 30% of the total geographical area.
- 22. Calcium concentration andtotal hardness in the study area
- 23. Conclusion ■ It isseen that the water quality is degrading very fast in the study area. In a short period of eleven years the calcium content and total hardness of groundwater has reached from the normal limit to a higher side of desirable limit of Indian standards (BIS) and crossed the limits of international standards. ■ The Calcium and total hardness concentration are high in downstream areas of limestone mine quarries. ■ Therefore, it can be concluded that the opencast mining pits of limestone mining are the major source of pollution of ground water, which is the main source of drinking water in this area. ■ Therefore, it is necessary to take the preventive measures in the study area to check the pollution in this area.
- 24. References ■ Indian MineralsYearbook (2018), Limestone and other calcareous materials, Indian Bureau of Mines, Ministry of Mines, Government of India. ■ Bhatnagar Devanu Et Al. (2014), Impact of opencast limestone mining in Katni river watershed, Madhya Pradesh, India – A geoinformatics approach, Journal of geomatics, Vol.8 ■ https://sciencing.com/weathering-erosion-harmful-23923.html ■ https://education.seattlepi.com/environmental-hazards-limestone-mining-5608.html