Orissa Review * July - 2006

Role of Chromite Mineralisation in Orissa

Er. Suryanshu Choudhury

Chromium is one of modern industry's essential Geological Set Up : element. Its strategic importance is attributed Chromite deposit of Orissa region to critical application in Defence, Aero-Space, mainly occur as bands, lenses and pockets in and Aviation among others. Chromite is the the serpentinised dunite peridotite. The only economic source of chromium and ultrabasin rocks are all of Precambrian age has fairly large resources of this mineral mostly parallel or sub parallel to major tectonic zones concentrated in the state of Orissa. of peninsular India and are intrusive into the pre-existing sediments and volcanics, Introduction : subsequently regionally metamorphosed and Chromite is the chief element for the tectonically deformed. The Sukinda ultramafic production of stainless steel, refractory, belt as well as igneous complex of Boula- ceramics, chemicals, electrode, fundry etc. It Nuasahi are intrusive into the Precambrian is the only economic source of chromium and metamorphites, namely the quartzites and Orissa has got large potential resource of this quartz muscovite sericite schists. Both are well mineral. Chromite ore mostly consists of differentiated layered igneous complexes. chromite with subordinate amounts of Chromite deposits of Pre Cambrian (Iron Ore ferrichromite, magnetite, ilmenite and Group and Eastern Ghats) and Tertiary age are secondary silicates like serpentine, talc, distributed in shield and tectonically mobile tremolite, uvarovite and kammererite. Though areas in India. Out of the 11 major chromite deposits distributed in 9 states of India, In the chromite grains are predominantly euhedral Orissa, the two major deposits i. e. Sukinda in nature, they exhibit two fold variations in Ultramafic Belt and Boula Nuasahi Igneous physical, mineralogical and chemical Complex hold around 98% of the total Indian characters which can be correlated with their reserve. Boula-Nuasahi Igneous complex formation at different stages during consists of three rock units i e., the ultramafic crystallization process. In this complex, rocks, mafic rocks and the felsic rocks. The chromites have crystallized in two stages. The ultramafic body, which hosts four chromite chromites from two stages differ in these lodes, occurs as a dyke like pluton of 3 km following aspects. long and 0.6 km width at the central part.

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Besides chromite, the ultramafic-mafic rocks are a suite of dunite-peridotite pyroxenite rocks host PGE mineralisation along with sulphides with less magnesium and pronounced gabbroic (Cu-Ni-Fe-Ag). differentiate, a younger granite and a still The chromite bearing ultramafics of younger swarm of dolerite dykes. Sukinda area have intruded into the The ultramafic body to the west of Precambrian metamorphites in the form of village Nuasahi extends for about 3 kilometers lopoliths. The intrusive has a width of 2-5 in a NNW-SSE direction from phuljhora Huli kilometers and extends for about 20 kilometers down to the village Jauthabahali. This is a dyke in an ENE-WNW direction from Kansa in the like steeply inclined body having distinct east to Maruabil and beyond in the west. The intrusive relationship with the older quartzite ultramafic body consists essentially of and epidiorite hills to the north. The ultramafic magnesite-rich dunite-peridotite with the body has a maximum width of about one chromite bands and subordinate amount of kilometer in the middle tapering gradually pyroxenite devoid of chromite mineralization. towards north and south and mainly consists There are as many as six chromite seams, fairly of a serpentinised dunite peridotite core and a thick and persistent both along strike direction subordinate amount of pyroxinite, almost in of the intrusive and with depth as observed in bysmalith form. The chromite bodies occur in the quarry and bore-hole sections from Saruabil the form of discontinuous bands and lenses, as in the east to Bhimtangar in the west. Further well exposed in the mines at the central part west at Kalarangi, Kathpal, Maruabil the and confined to the altered dunite peridotite. chrome ore bodies do not exhibit any regular these bands have a NW-SE to NNW-SSE alignment, rather these are exposed in strike with moderate easterly dip and an disjointed bands and lenses apparently average width of 5meters1. disrupted by the emplacement of younger Classification of Chromite Ore: granite. The granite is exposed at several places around Maruabil and also encountered in the Chromite deposits have been classified borehole sections at the western part of broadly into two groups as stratiform and TISCO's quarry, Kalarangi and kathpal mines. Alpine type. Stratiform deposits are sheet-like Small exposures of diorite are found in kathpal or lopolith in form, extend over large area and and Bhimatangar. Besides, several dolerite characterized by both rhythmic and cryptic dykes have intruded into the ultramafics, layering, thickness of individual layers varying quartzites as well as the granites. This happens from a few centimeters to meters. This to be the last stage of igneous activity in this accounts for about 90% of the total chromite Precambrian terrain. Soil, alluviam and laterite resources. The Alpine type deposits are of recent origin overlie ultramafics characterized by irregular form such as pods unconformably. or lenticular, limited extension, small reserve The area around Boula-Nuasahi consists and high chromium content. of older quartzites which include massive, Depending on compositional variation, ferruginous and micaceous varieties. The chrome ore can be divided into the following intrusive into these Precambrian metasediments three categories:

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Ore Type % Cr2O3 % Al2O3 Cr:Fe of 78.39sq.kms. Of these fourteen are in High Chromium 46-55 ---- >2 operation. The leasees include TISCO, OMC, High Iron 40-46 ---- 1.5-2 FACOR, ISPAT ALLOYS, IMFA, IDC, Mishrilal Mines, B.C Mohanty & sons etc. High Aluminium 32-38 22-34 2-2.5 Except Kathpal mine of FACOR, all mines in Resources of high aluminum chromites Sukinda sector are open cast. The ore to are negligible. Orissa deposits are overburden ratio ranges from 1t: 3m3 to predominantly stratiform, high chromium and 1t:20m3. Production of chromite in India during high iron types. Sukinda chromite is relatively 2001-2002 is estimated to be 19.67 lakh tonnes rich in chromium and magnesium contents, out of which Orissa accounted for 19.47 lakh does not exhibit pronounced variation in the tonnes (99%) of total production. spinel constituents of different horizons and Uses : invariably has Cr/Fe ratio of more than three. Chromite is the only Commercial ore Reserve and Grade : mineral of chromium. Traditionally, chromium The world resources of chrome ore are ores have been classified as metallurgical, of order 7,500 million tones, of which Republic chemical and refractory grades, according to of South Africa and Zimbabwe account for the expected industrial end uses. However, 85% and 10% respectively. Although India recent technological advances have allowed with a resource of 186 million tonnes account some degree of interchange in the usage of for only 2.5% of world resources, chrome ores these three product categories so that the of Sukinda valley of Orissa State have a distinct classification has become less meaningful. edge over other major deposits of the world in Current nomenclature is based upon chromite terms of quality, large widths of ore bands and composition in addition to end use. High- amenability to simple beneficiation process. chromium ores, defined by high chromium-to- Out of 186 million tones in India, Orissa iron ratios, are used for making ferro- accounts of 183 million tones i.e 98.39% and chromium for metallurgical applications. High- bulk of it are confined to Sukinda ultramafic iron chromites, previously limited almost belt.5 entirely to the production of chromium-based chemicals, are now finding growing usage in Mining : the production of low-quality ferrochromium, Deposits of Chromite in Boula-Nuasahi refractories and foundry sands. High-aluminum area of Keonjhar district was discovered in chromites with relatively low iron and silica 1942 and mining started from 1943. The area have application mainly for refractory around Nuasahi lies at the south-eastern fringe purposes, primarily in the manufacture of of Boula state forest. About 70 Kms. south- magnesite-chromite and chromite-magnesite west of Boula-Nuasahi lies the Chromite bricks3. deposits of Sukinda Ultramafic belt of - The principal use of chromium Dhenkanal district. ferroalloys is in the production of stainless and In Orissa eighteen leases have been specialty steels, such as heat-resistant and tool granted for mining of chromite covering an area steels. Most applications of stainless and heat-

59 Orissa Review * July - 2006 resistant steels or refractory metals are in tanning agents for all types of leather; and for corrosive environments such as petrochemical chromium electroplating, anodizing, etching processing; in high-temperature environments, and dipping. Chromium compounds are also such as turbines and furnace parts; and in used as oxidants and catalysts in the consumer goods, such as cutlery and decorative manufacture of various products such as trim. Chromium is added to alloy and tool saccharin; in the bleaching and purification of steels to increase their hardening ability and oils, fats and chemicals; and as agents to improve their mechanical properties such as promote the water insolubility of various yield strength. Super-alloys containing products such as glues, inks and gels2. chromium has a high degree of resistance to Conclusion : oxidation and corrosion at elevated temperatures and is used in jet engines, gas Orissa is endowed with vast tur-bines and chemical process equipment. mineral deposit of Chrome ore and hosts the Chromium-containing castings are usually used largest chromite reserve of the country. Being in high-temperature applications. The a lion share holder of chrome ore in India, refractory industry uses chromite in the Orissa bears huge industrial potential in near manufacture of refractory bricks, castables, future. This is one of the chief export items of mortars and ramming gun mixes. Refractories the State due to which Orissa enjoys a strategic containing both chromite and magnesite are position in mineral trading in the country and used in furnaces wherever basic slags and dust has appeared on the investment map of India are encountered, such as in the ferrous and with a long list of investment proposals, largely nonferrous metal industries. In the ferrous backed by foreign investors due to this resource industry, a chromite-magnesite brick is used potential. As far as economic benefits of new in electric arc furnaces, while basic oxygen investments and are concerned, the State furnaces, which operate at higher temperatures, government boasts that the new investments require magnesite bricks. In general, refractory will spur growth which, in turn, will help in requirements in the steel industry have changed industrialization of the State. to a higher magnesite-content brick, thereby Reference : decreasing the consumption of chromite in this 1. Geology And Mineral Resources of Orissa; application. However, overall chromite Society of Geoscientists and allied refractory consumption in the steel industry is Technologies;1998. expected to stabilize in the next few years. In 2. www.sci.u-szeged.hu/asvanytan/ acta/ the nonferrous industry, chromite-magnesite acta42fulltexts/AMP_mohantyVol42.pdf bricks are used mainly in converters, while the 3. http://steel.nic.in/chromite_ore.htm glass industry uses a chromite-magnesite brick in the reheating chambers of glass furnaces. 4. www.cyberorissa.com/myorissa/naturesors/ minerals.htm Most chromium chemicals are produced from sodium dichromate, which is manufactured 5. www.nrcan.gc.ca/ms/invest/ind/cwg.pdf directly from chemical-grade chromite. Chromium compounds are used as pigments, Er. Suryanshu Choudhury is the Technical Support mordants and dyes in the textile industry; as Engineer, Surpac Software India Pvt Ltd, Bhubaneswar

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