BAILADILA IRON ORE MINES
National Mineral Development Corporation Limited (NMDC) is a fully owned public enterprise under the administrative control of the Ministry of Steel, Government of India. The company was established in the year 1958 with an objective of mineral exploration & exploitation, primarily to support the demand of raw materials for iron & steel industry of the country as well as to meet the requirement of export of high grade iron ore. In addition to iron ore, the company has been involved in development of wide range of other minerals such as copper, rock phosphate, limestone, dolomite, gypsum, bentonite, magnesite, diamond, tin, tungsten, graphite, beach sands etc.
The large operating mines like Kiriburu, Megahatuburu iron ore mines in Jharkhand, Khetri Copper deposit in Rajasthan, Kudremukh Iron Ore Mine in Karnataka, Phospha te deposit in Mussorie, etc. were initially developed by NMDC, which were later, handed over to other companies in public sector.
Presently, NMDC is India’s single largest iron ore producer and exporter, producing 22.9 million tonnes (FY – 06) of iron ore from fully mechanised mines viz., Bailadila Deposit-14/11C, Bailadila Deposit 5,10/11A & and Donimalai Iron Ore Mines, which are ISO 9001-2000 – certified. It also operates the only mechanised diamond mine in the country producing around 80,000 carats at Panna (Madhya Pradesh). With the strong and long experience in iron ore mining, the Corporation is poised to further extend their acivities by developing large capacity iron ore mines at Bailadila’s 11 B deposit and Kumaraswamy deposit in Bellary Sector – the engineering activities for which have already been initiated. The downstream value addition in form of iron/steel making, utilizing their own iron ore mines, has also been actively considered.
Bailadila range of hills are located at a distance of about 40 Kms south west of Dantewada, the district headquarters in Chhattisgarh State. The area falls in Toposheet No. 65 F/1, F/2, F/5 & 65 F/6 and is located between latitude 18 degree 35 minute 48 second and 18 degree 38 minute 30 second and longitude 81 degree 13 minute 22 second and 81 degree 16minute.
Bailadila is easily accessible and well connec ted to Raipur, Visakhapatnam and Hyderabad by all-weather roads. It can also be reached by rail from Visakhapatnam. Raipur is located at a distance of about 425 Kms from Kirandul by road while Visakhapatnam is about 450 Kms away. The project can also be reached by road from Hyderabad which is about 700 Kms away. There is regular iron ore movement from this sector to Visakhapatnam port by rail. The railway line, known as KK line runs at the foothills of Bailadila – 14, 11C, 11B.
Bailadila region enjoys mild summer and win ter is not severe. The maximum temperature in summer rises up to 40 degree celsius between May & June whereas minimum temperature in win ter drops to 10 degree celsius. The area receives heavy rains during monsoon from June to October. Weather during rainy season is stormy accompanied by gales and the hilltops are covered with thick clouds and dense fog, which reduces visibility.
There are number of perennial streams flowing from the hills and the entire region is a part of Godavari Basin.
The Bailadila iron ore range extends for a length of 40 km with width of about 10 km mostly along the top of hill, constitute of the richest concentration of iron of world. The range contains 1200 million tonnes of high grade iron ore distribu ted in 14 deposits. The entire area was brought to the mainstream of civilisation by the spectacular effort of NMDC by opening-up of mines. Today, Bailadila is a name to reckon with in the world iron ore market because of its super high-grade iron ore. Bailadila complex possesses the world’s best grade of hard lumpy ore having +66% iron con tent, free from sulphur and other dele terious ma terial and the best physical properties needed for steel making.
The Commercial discovery of Bailadila dates back to 1955-56 when Prof. Euemura of Japanese Steel Mills Association, studying the memories of Geological Survey of India, draw the attention of the Japanese Steel Mills to the richness of the vast deposits of iron ore and its proximity to the Eastern Coast of India. Later an agreement has been signed with the Japanese Steel Mills in 1960. An approval of the project report prepared by NMDC has been given in 1964 and the Mine Plant has been inagurated in November 1968.
Deposit number 5 is the southern most deposit in the western ridge of Bailadila iron ore range. The deposit has strike length of 3500 m and the width varying between 100 m to 400 m. The western side of the mine is marked by a cliff, which goes almost vertically down for about 300 m. The ore body strikes N37 O and has the dip varying between 45 degree to 60 degree towards east. The south block has a strike length of 1 km, where as the central and north-west blocks have a strike length of 1 km and the north block occupying the rest of the area.
Bulk density of major ore types
|S.N||Ore type||Fe%||Bulk density, (t/m 3)|
|1||Steel Gray Hematite||69||4.5|
|2||Blue Gray Hematite||68||4.2|
|4||Lateritic/ Limonitic Ore||60||3.2|
|5||Flaky Ore/ Blue Dust||66||3|
Bulk density of major waste rocks
|S.N||Rock type||Fe%||Bulk density, (t/m 3)|
Deposit 10 is located in the middle of eastern limb of the folded mountain range of Bailadila iron ore reserves. The general trend of the ridge is N – S direction. The country rock dips to east. The total length of ore body is 2600 m out of which about 1100 m forms the south block. Average width of ore body is about 400 – 500 m normally extending up to 600 – 750 m, in East – West direction. Ore occurs from 1203 MRL upto 1000 MRL. The ore concentration is mostly towards east of the central axial line comprising outcrop of massive ore, laminated ore and lateritic ore. The ore body is divided into two blocks on the basis of geology and ore characteristics.
Deposit 11A occurs immediately to the north of deposit 11B on the eastern ridge of folded mountain range of Bailadila. The deposit is bounded by deposit 10 in the north. Towards the east, the deposit slopes steeply towards Bacheli and to the west the deposit slopes towards Galli Nalla. The ore deposit is confined to an elongated hill running almost North – South for a strike length of 2500 meters. The ore body is divided into two parts viz. North Block and South Block. The North Block ore shows scanty and poor development of iron ore. The south block consists of ore of better grade. Average Fe content is 65.81% and the width of ore body is 50 to 250 m.
Deposit-11C falls under the mining lease area of Deposit-14 Non Mineralized Zone (NMZ) and Deposit-11. Deposit-14 NMZ mining lease, measuring 506.742 ha covers major part of Deposit-11C and only 106.412 ha area of deposit 11C falls under the mining lease of deposit 11. The deposit is located in the southern extension of the eastern ridge of Bailadila range. The iron ore in this area predominantly comprises of hematite ore forming the ridge and is underlain by banded hematite quartzite and tuffaceous ferruginous shale, which is underlain by a sequence of clastic and mixed tuffaceous and clastic formations.
The ore body of Deposit-11C trends roughly in N-S direction and extends for a length of about 2.3 km with width varying from 125m to 750m. The area under present mining operation, however, has a length of about 1.7 km. The deposit in the central part is relatively shallow, the bottom formation of BHQ or ferruginous shale bearing horizon encountered within a depth of 50-66m. Deposit-11C ore is predominantly powdery in nature being constituted mainly of blue dust with occasional pockets of massive ore. At present, the deposit is being worked at the top benches which contain a large proportion of low grade laterite. There are only a few intercalated shale bands within Deposit-11C ore body. However, pockets of BHQ have been encountered in bore holes and mine faces which will assume larger proportion in the later period of mining operation.
The Mining Lease area of deposit 14 (14ML) covers 407.55 hectare of land in Bailadila reserve forest which was obtained for a period of 30 years in September 1965 and commenced production from 1968 with integrated infrastructure facilities for processing, transportation and loading of ore into railway wagons. Deposit 14 is the last deposit at the southern end of the eastern ridge of Bailadila range and trends roughly NNW-SSE with a length of almost 1.5 km and width of about 400m. The dip of hard ore strata varies from 80 degree to 85 degree east and 60 degree to 65 degree east in soft ore zone. The north-western part of the deposit comprises of predominantly blue dust while the rest of the deposit is constituted by massive ore and mixed massive ore and blue dust. The Deposit is divided into three longitudinal segments by two major shale bands parallel to the strike. The western most segment occurring along the cliff is constituted entirely by massive ore with the compaction increasing towards south east and decreasing towards north west. The intermediate segment is constituted by mixed massive ore and blue dust, the south eastern end being almost entirely massive ore. The eastern most segment is predominantly powdery ore with some admixture of massive ore. In addition to the two major shale bands, there are numerous small intercalated shale bands within the deposit. There are also a few pockets of BHQ generally occurring within the blue dust zones. The lithological units found in areas outside the ore boundary include BHQ, ferruginous shale, green chloritic-phyllitic and banded magnetite siltstone. These are underlain by low grade metamorphic rocks such as phyllite-quatz-actinolite-schist etc. Laterite capping however covers almost all rock types and the formations can be observed only in deep man-made or natural cuttings. All formations including the iron ore boundary show structural conformity with. prevalent strike in NNW-SSE.
Ore types and average Fe content
|Sl. No.||Ore Type||Average Fe (%)|
|1||Steel Grey Hematite||68|
|4||Lateritic / Limonitic||62|
|5||Blue Dust / Flaky Ore||67|
|6||Banded Hematite Quartzite (Waste)||42|
Bailadila Deposit – 14 mine is a fully mechanized opencast mine deploying Heavy Earth Moving Machinery. Bench height in the hard ore horizon is 12 m with 12 m wide berm left at pit limit while 10 m high bench having a berm width of 20 m has been maintained in Blue Dust & Laterite. The bench slope angle recommended by CMRI for hard & compact ore like massive Steel Grey Hematite, Blue Grey Hematite, Blue Hematite & BHQ, for soft & friable ore like Laterite, Limonite, Flaky ore & Shale and for Blue Dust Zone are 50 degree, 40 degree and 30 degree respectively. The different bench slopes for different ore type could not be maintained as the ore is intermixed at each bench. However, a berm width of 12 – 15 m was maintained in Blue Dust benches.
DRILLING- There are three nos. of IDM – 70 E rotary drills having 250 mm (10″) diameter & two no. of 150 mm (6″) rotary percussive drills. All drills are electrically operated. Primary drilling is done by 225 – 250 mm rotary drills & 150 mm rotary percussive drills. These drills are capable of drilling upto 16 m. Secondary drilling is done by two nos. of crawler mounted 4 ½” rotary percussive drills working on compressed air & powered by diesel engine. Blast holes are drilled in the staggered pattern. For 12 m high benches 10″ drills are used while for 10 m high benches 6″ drills are preferred.
BLASTING- In Bailadila Deposit – 14 mine, hole depth in 12 m high benches varies from 13 – 14 m & that for 10 m high bench it varies from 11 – 12 m depending upon rock type. The holes are charged with either Site Mixed Emulsion (SME) explosives or Site Mixed Slurry (SMS) explosives. Average charge per hole varies from 400 – 500 kg and 175 – 225 kg for 250 mm & 150 mm diameter hole respectively. Cast booster used per hole is 0.2% of total column charge. Detonating Cord of 10 g/m core load is used for trunk-line and EXCEL of 400 ms & 450 ms delay is used as down-line for initiation. Staggered V pattern of initiation is used for firing of explosives. Row to row delay is kept to be 50 ms while delay of 400/450 ms is used down- the-hole. Stemming height varies from 5 – 6 m depending upon the type of strata. Powder factor varies from 5.5 – 6.0 T/kg, which is very low due to high strength of the ore. Details of blasting practice of Bailadila Deposit – 14 mine is presented below.
Blasting Practices at Bailadila Deposit – 14 mine for 12 m high bench/250 mm diameter hole
|Sl.No.||Parameters/Rock Type||Very Hard Ore||Hard Ore||Medium Hard
Ore / Shale
|Soft Ore/Soft Shale|
|1||Bench Height, m||12||12||12||12|
|2||Blast Hole Diameter, mm||250||250||250||250|