Thrust Area : Mining and rehabilitation of mined areas

Title of the Project: ECO-DEVELOPMENT IN EASTERN GHATS WITH SPECIAL REFERENCE TO GRAPHITE MINING AREAS IN ORISSA

Keywords: Mining, Rehabilitation, Selected Plant Species

Orissa is the leading producer of graphite in India. The graphite deposits of Orissa are confined to Precambrian Eastern Ghats Complex and are found in the district of Bargarh, Bolangir, Kandhamal, Boudh, Kalahandi, Koraput, Rayagada, Nayagarh and Angul But the majoprity of the graphite deposits are located in the districts of Bargarh and Bolangir. Graphite occurs as disseminations, schists and lodes/veins. The graphite schists and lodes which are mined economically pinch and swell both in the strike and dip directions and taper towards both ends. Graphite mining is an important activity in the Western Orissa. This reports incorporates the findings on the lithology, structure, mode of occurance, graphite mining practice and the assessment of eco-degradation in and around graphite mines in Bargarh, Bolangir and Kandhamal districts of Orissa.

The findings embody information on the graphite mining, the associated environmental problems in parts of the Eastern Ghats complex of Orissa and possible remedial measures. The data includes distribution of graphite in Orissa , the modes of occurrence of graphite, controls of graphite localisation, associated mineral impurities and the genesis of graphite. The Bargareh-Bolangir zone is very important from the point of view of graphite production and the number of mines. Graphite occurs as dissemeniations, schists and lodes/veins. Khondalites, calsilicate granualte and pegmatite are the lithological controls while the foliations, fold hinges are the structural controls. The graphite lodes in many cases are controlled by folds of different generations. The mineral impurities identified in the graphite ores are quartz, orthoclase, calcite, microcline, plagioclase, perthite, biotite, muscovite, kaolinite, wollastonite, garmet with minor to trace amounts of sericite, chlorite, sphene, epidote, zoisite, apatitte and zircon. Pyrite, chalcopyrite, pyrrhotite, magnetite, henatite and geothite are also associated in some cases. The graphite mining and benefication practices in Orissa have been described.

Poor geological knowledge, irregular distribution, structural complexities and short term planning have led to a very unscientific and unsystematic open graphite mining in Orissa. As a result, the entire graphite resources can not be mined out and ecological disturbances are caused with respect to soil, water and plant species. The grade of graphite is low and requires beneficiation before marketing. The beneficiation units are invariably located by the side of small rivers and the rejects including slimes and effluents are directly discharged to these rivers

without any treatment. These affect the quality of water. The mineralogical, physical and chemical characteristics including nutrients of the different graphite mine dump samples of Bargarh and Bolangir districts have been reported. The mineralogy, and the major and minor elements of the dumps samples vary widely depending on the rock types, weathered products, soil and their proportions. The dump samples are very poor in nutrients contents. The physical, chemical and minerological characteristcs of soil samples collected from various graphite mining areas in the districts of Bargarh,Bolangir and Kandhamal have been described. Generally, the soil types vary in PH from 5 to 6.67 and are sandy loam type. Minerologically, the soil samples are constituted of quart, orthoclase, plagioclase, garnet, illite, kaolinite, biotite, chlorite, sillimanite, wollastonite, sacapolitre, graphite, zircon, diopside and goethite.The minerological and chemical characteristcs of the soils derived from different parent rock types have been established. The chemical variation from soil to parent rocks through intermediate weathered products are also established.There is no remarkable variation in the major and minor elements in top soil samples of different areas but, their trace element concentrations are highly variable. The available N, K, P in soil vary from 0.049 to 0.148 mg/g, 0.033 to 0.44 mg/g and 0.001 to 0.017 mg/g respectvely indicating low to medium N, low to high and low to medium P. Organic carbon and sulphur contents of the soil samples vary from 0.089 to 1.48 and 0 to 0.27 % respectively.

The crop choice around different graphite mines indicates that crops adopted at mining areas of Bargarh and Bolangir disrcits are Green gram (Mung), Til, Groundnut, Horse gram (Kolatha), Fox tail (Gulji), Rice , Ragi(Mandia),Vigna (Kesar dal),Sunflower and Black gram (Biri) whereas around Tumudibandha mining area, Kandhamal district Zinger, Tobacco, Turmeric (Haladi), Til, Kandula etc. are growing well. The difference in crop pattern appears to be due to variation in some of the trace elements.

Water samples were collected from different graphite mining areas in Bolangir and Bargarh districts during summer and winter seasons and analysed for Ph,DO,BOD,GPP,NO2,NO3,NH3,T.H..SO4,P,Ca,Mg,Na,K,Fe,Co,Ni,Cr,Mn,Cd,Pb,Zn,Cu,As. The majority of the water samples are either within the desirable limits or within the permissible limits in view of the absence of alternate source of water for drinking purpose. The mine water from Tumudibandh, Kandhamal district and the beneficiation plant effluents are highly acidic and contain much higher amounts of Fe, Mn, Ni, and Cu above the specified limit indicating their unsuitability. The discharge of the beneficiation plant effluent to the Raul nadi add impurities like Fe, Ni, Mn, SO4, P, NH3, NO3, and NO2. However, except Fe and Ni all the parameters are well within the specified limits of drinking water. However, the samples from the near by tube and dug wells are suitable for drinking purposes.The graphite mine water quality data obtained from the present studies are also very important for the health of people living in those areas.

The mining has resulted in reducing the fertility of the nearby soils due to spreading of overburden material. The fine generation has obviously increased due to mechanisation of graphite mines. Leaf injuries leading to necrosis, death or degeneration of epidermal cells are some of the symptoms encountered in some cases. The trees have lost their arboreal identity and present themselves as highly degraded, much branched, stunted and crooked stems. The shrubby elements dominate the floristic composition.

Out of 26 species (10 exotic and 16 indogenous) tried in the laboratory experiments, the successful plant species, viz. Grevillea pteridifolia, Sapindus trifoliatus, S. mukorossi, Simarouba glauca, Azardirachta indica, Emblica officinalis, Calophyllum inophyllum indicated by the laboratory experiments were transferred to mine sites at Temerimal, Bargarh district and Ganjaudar, Bolangir district for the reclamantion programme. Among these Grevillea pteridifolia has shown excellent growth performance and regeneration.

Period of study: 1995-1999.

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Principal Investigator: Dr. B.C. Acharya, Mineralogy & Mettalography Division,Regional Research Laboratory,Bhubaneswar-751013.