DALLI IRON ORE MINE
It is located in southern Durg district .The preparations for mechanizing the Dalli mine began
in 1977.The mine area covered 14 ha. This mine contorolled by Steel Authority Of India Ltd. The Dalli Rajhara
iron ore mines feed into the Bhillai Steel Plant.
The occurrence of gold in the Banded Iron Formation has been established in Dalli-Rajhara area of Durg district.
The actual production in Dalli mine of Bhilai Steel Plant (BSP) exceeded the rated capacity during the
year 1992-93 to 2002-03 by producing on an average 97.4 per cent (85.5 per cent for lump and 112 per cent for fines)
of the capacity.
Iron ore in Dalli covered area about 85 square kilometers.Iron ore in Dalli are bandes of hematite and quartzite.
Iron ore are lentiform and it seen in various size.
Chemical composition of dalli iron ore is as follows-
It is well known that the iron and steel industry is one of the fundamental industrial sectors of the national economy
in most countries in the world, as well as a key material base for the development of an integrated national industry
complex and rapid growth of the national economy.
RAJHARA IRON MINE
The Rajhara Iron Mine is situated approximately 90 km south of Durg in the Indian state of Chhattisgarh
and supplies iron ore (haematite) to the Bilhai Steel Plant near Durg, to which the mine is connected by
dedicated railway. The orebody (seen above) is a Precambrian banded iron formation and is worked on a very
large scale in a highly mechanised opencast mine.
Rajhara Mechanized Mine is one of the 2 principal sources of iron supply to the Bhilai Steel Plant. The mine
was started in 1960, with commissioning of its processing plant in 1960.
Location 95 km from Bhilai in Bhalod Tehsil of Durg Distt (CG).
Latitude 20° 33’00” to 20°35’00” N
Longitude 81°00’45” to 81°07’00 E
It is a hilly terrain. The general ground level is located at 425 mRL and the peak old benches
are at 543 mRL The drainage of the region is controlled by Jharan nallah and cutting across Rajhara and Dalli hills.
General strike is in East West direction with a varying dip of 40 to 60 degrees due N to N-E. The resistant
outcrops of iron-ore in Rajhara area form conspicuous hillocks and ridges in the general peneplane giving rise to a saddle type of topography.
The iron deposit of the Dalli Rajhara range are associated with the BIF(Banded Iron Formatitions) belonging to the Chilpi formation of Pre-Cambrian age, generally known as iron-ore series of Dharwarian system. The lithology of this area is dominantly of the sedimentary-metamorphic type. Hard massive and abrasive BHQs (banded hematite quartz) and
soft phyllites/shales respectively constitute the footwall and the hangwall. The iron ore is extremely rich and is hard and massive in nature at the upper horizons with the gradual softening at the depth.
The starting reserves were 112 MT. The ore body continues down to 330mRL where it bifurcates into 2 distinct parts, finally pinching out at 250 mRL. The current reserves are as follows (fig. as on 1.04.2006).
As per the study conducted by METCHEM Inc, Canada . the minerable reserves occur upto 273 mRL. Due to its very rich iron ore, this is the principal sweetener for feed ore to Bhilai and needs to be mined out over the life of the Iron Ore Complex.
A unique features of this mine is the high stripping Ratio, which is normally very marginal in other iron-ore mines in the country. The overall stripping ratio for the deposit is 1.5(waste:ore), whereas, it is as high as about 4.6 for the upper horizons, i.e for + 423mRL.
The mine is being worked with the standard open-pit technology deploying a combination of 50 T rear dump dumpers and 4.6/5 cubic meters electric rope shovels and 4.5 cubic meter diesel hydraulic shovels operating 10 m high benches in ore and waste.
Drilling and Blasting
Primary drilling is done with 152 mm dia IDM-30 E electrically powered (6.6 kv) down hole drills.
The general parameters are as below.
|Burden||3.5-4.5 m||4-4.5 m||5-6 m|
|Spacing||4-4.5 m||4-5 m||6-7.5 m;|
|Sub-drill||0.3-0.4 B||0.3-0.35 B||0.1-0.2 B|
Blasting is carried out by using Acquagel and Emulsion cartridge slurries of various manufacturers.
Initiation is carried out by using EXEL shock-tube non-electric detonation system of in case of ore and BHQs.
Det fuse of 10 g/m with cord relays is used for initation of blasts in soft rock.
All the benches in ore and waste are kept 10 m high with minimum 20 m width for operating benches.
|Footwall||463,453,443,433,423,413;||473||483 and above|
|Hangwall||453,443,433,423,413||453,463,473,483,493||503 and above|
In footwall area, benches 483 and above and 473 (excluding west flank) have already been pushed for their ultimate pit position In h/wall area, 503 and 513 benches are at their ultimate position. The dormant benches, 453 to 573 mRL, will be excavated after the upper horizons have gone to their ultimate limits. The existing pit bottom is at 418 mRL and the sump at 418 mRL.
The ground water occurs at about 430 mRL. In addition to the ground water, the precipitation catchments of the pit also get collected during the monsoons. Average dewatering qty (based on the pumping avgs. For 97-98 and 98-99) is around 1050cum/day. A sump of around 2000 m2 area with top at 418 mRL and bottom at 414 mRL has been given. Pontoon mounted pumps (2×45 Kw, 150 cum/hr per pontoon) are available for dewatering. 2 pontoons are kept afloat of which 1 pontoon is normally operated. However, no mining is being carried out below 443 mRL due to MMR-108 restrictions and as such; pumping is not being made to save electricity. The water logged area of 418 mRL has been fenced off. Dewatering is continuing below 418 mRL is commenced.
At present, the water conserved at the pit bottom is being used for reticulation /dust suppression of the haul roads. Temporarily it is discounted due to relocation of pipeline that is under process. Hydro-geological study is under progress by CMRI, Dhanbad.
MetChem in their study had recommended an overall ultimate pit slope of 45 degrees in h/wall,
with an FS greater than 2 and slope coplanar with the f/wall area. Excerpts of the study are enclosed.
Subsequently, a final pit design has been made by CET, SAIL in 2001. In this design, the overall f/wall slopes come to around 450 and the h/wall slopes ranges between 38-42 degrees. The flattening in h/wall slopes has resulted from inclusion of haul road berms for optimizing the haulage. Pit slope study is under progress by CMRI, Dhanbad.
The manpower includes the persons deployed in open cast workings and those deployed in above ground operations both. However, the above figure excludes the executives.
Principal Mining Equipment
|No.||Equipment||Type||Total fleet||Under major b/d or o/haul||Physical fleet|
|2||Electric shovels||EKG 4.6B, 4.6/5 cuM;||7;||0||7|
|3||Hydraulic Shovels||Demag H121, 4.5 m3||3||2||2|
|4||Track Dozers||BEML D-155
|5||Wheel Dozer||BEML G-30D||1||1||0|
|6||Motor Graders||BEML G-605 R2||2||1||1|
|7||Primary Drills||152 mm dia IDM-30 E electrically powered (6.6 kv)||4||1||3|
|8||Secondary Drills||IR ICM-20, LM-100 105/115 mm dia.||2||2|
|9||Diesel compressors||CPS 450, IR XHA400||2||1||1|
|10||Water Spriklers||BEML28 KL, pressurised||2||1||1|
Production at Rajhara Mechanised Mine 2007-08 : 1 MT
Processing of ROM ore is done in the crushing and screening plant, Rajhara which is a dry circuit plant having 3 stage crushing and double check screening. Primary crushing of the 0-1200 mm ore is done in 2 no.s of 1600 x 2400 double toggle, 250 KW, avg 750 TPH jaw crushers with OSS of 1500 mm and CSS of 180-190 mm.
Secondary crushing is made in a KKD2200 Cone Crusher at a CSS of 52-56 mm. The secondary crushed ore is screened at Double Deck Screens, 40 x 40 mm/10×10 (or 10×16 PU), 3 nos Linear Motion and 4 nos of Inertia Screens.
The +40 size is subjected to a tertiary Crusher, Short Head Hydrocone, 200 TPH, operating at 10-22 mm CSS.
The +10-40 mm size , BF lumps are stored in 10 nos of 120 T loading bins or 6 nos of 35 KT capacity bays .
The -10 mm sinter fines are stored in 3 nos. of 35 KT Bays . A little quantity of +40-100 mm lumps, OH lumps, about 5000 T/Month is bypassed and stored in a 35 KT bay for use in open hearth furnaces.
Rated capacity of the plant is 3.5 MT in 3 shift, 6 days operation. No washing is being done since the alumina content is nominal and does not warrant any washing or classification etc.
The finished ore is loaded into rakes of 45 BOBS wagons with CC of 63 T at the Bottom Station. Lumps are loaded through Bins and shovels at the BF bays. Fines and OH lumps are exclusively loaded by shovels. The sliding has an average capavity of 3.3 rakes/day in 3 shifts, 365days/yr.
The deposit is worked in benches to produce very large excavations. In the mine reclamation plans, the excavation above will be partly filled with water. The benches themselves will be difficult to revegetate.