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Basic Concepts of Surface Mining
Minerals are the basic raw materials for manufacturing the goods required for fulfilling the needs of the developed society. Fossil fuels like coal and lignite are still the major sources of energy in the world. The minerals and fossil fuels occur in the earth at different places of the earth under different situations. Mining is the process by which these earth resources are made available for human welfare. Earth scientists i.e. the geologists and geophysicists explore the occurrences of mineral resources and provide the necessary information regarding how particular mineral deposits exist under the earth surface. Mining engineers use this information to determine the amount of economically mineable resources considering the grades of the deposits, processing needs, market demands and the technology available for m ining the deposit. Thus it is essential for the mining engineers to understand the basic terminology the geologists use for describing the occurrence of mineral deposits. These are covered in the course of Geology that is compulsory for any undergraduate mining engineering course. The important definitions are discussed below for quick recapitulations.
Ore The earth materials from which metals are extracted economically are called ores. Ores occurs in many different kinds of rocks and in many different geological environments.
Deposit
The metalliferous compound compound from which metals are extracted is concentrated by geologic processes to form commercial deposits at specific locations. Types of deposits vary with metal to metal. Gold deposits are of two principal types: lode (primary) deposits and placer (secondary) deposits.
Hypothesis of formation of Gold Deposits One widely accepted hypothesis proposes that many gold deposits, especiall y those found in volcanic and sedimentary rocks, formed from circulating ground waters driven by heat from bodies of magma (molten rock) intruded into the Earth's crust within about 2 to 5 miles of the surface. Active geothermal systems, which are exploited in parts of the United States for f or natural hot water and steam, provide a modern analog for these gold-depositing systems. Most of the water in geothermal systems s ystems originates as rainfall, which moves downward
through fractures and permeable beds in cooler parts of the crust and is drawn laterally into areas heated by magma, where it is driven upward through fractures. As the water is heated, it dissolves metals from the surrounding rocks. When the heated waters r each cooler rocks at shallower depths, metallic minerals precipitate to form veins or blanket-like ore bodies. Another hypothesis suggests that gold-bearing solutions may be expelled from magma as it cools, precipitating ore materials as they move into cooler surrounding rocks. This hypothesis is applied particularly to gold deposits located in or near masses of granitic rock, which represent solidified magma. A third hypothesis is applied mainly to gold-bearing veins in metamorphic rocks that occur i n mountain belts at continental margins. In the mountain-building process, sedimentary and volcanic rocks may be deeply buried or thrust under the edge of the continent, where the y are subjected to high temperatures and pressures resul ting in chemical reactions that change the rocks to new mineral assemblages (metamorphism). This hypothesis suggests that water is expelled from the rocks and migrates upwards, precipitating ore materials as pressures and temperatures decrease. The ore metals are thought to originate from the rocks undergoing active metamorphism. Placer deposits represent concentrations of gold derived from lode deposits by erosion, disintegration or decomposition of the enclosing rock, and subsequent concentration by gravity. Classification of Deposits
Basis
Types
Description
1. Shape
Isometric
Extending in all directions, e.g. massive deposits, bosses, nests
Bedded, flat
Stretched in two directions, layers
Pipe-like and
Extended in one direction
columnar Intermidiate
Lens, vein, folds, bends, tectonically dislocated strata
2. Surface
Slope
Relief
Hill 3. Position
Surface type
OB thickness of 20-30 m
Deep
OB thickness 40-250m
High Type
Above the prevailing surface
High-Deep
Partially above and partially below the prevailing surface
Gently dipping
Dip upt 8-10
Dipping or inclined
Dip between 8-10 to 25-30
Steeply dipping
Dip more than 25-30
Steep
Dip within 56-90
with respect to surface
4. Angle of
0
inclination
5. Complex bedding
0
0
0
0
Anticlinal or synclinal folds, faults, variable dip
When mining horizontal and gently dipping deposits, it is possible to locate waste dumps in the mined out area of a quarry. This is sometimes possible in the mining of dipping and steeply dipping stretched deposits.
I I I
II
II III
III
Hq
II III III
What is surface mining? Surface mining can loosely be defined as extraction of valuable minerals, coal or lignite by fo rming pits. Surface mining basically involves three specific tasks. These are stripping, mining proper and development.
DEVELOPMENT
OB
STRIPPING
REMOVAL TRANSPORTATION DISPOSAL
Road MINERAL EXPOSED
MINERAL
MINING PROPER
Pumping
EXTRACTION HAULAGE STORAGE RECLAMATION
Trenching Figure 1 Broad groups of surface mining operations.
Stripping includes removal, haulage and disposal of over burden. Mining Proper means extraction, haulage, storage and unloading of valuable minerals. Development tasks are manifold. All other activities necessary to stripping and mining proper are categorised as development activities. Trenching, pumping, road construction, etc. are some of the important development tasks.
Schemes of Opencast Mining of Deposits
NON-WORKING BENCH INTERNAL WASTE DUMP
MINED OUT SPACE
WORKING BENCH
ULTIMATE PIT CONFIGERATION
Hq
EXTERNAL INTERNAL WASTE
WORKING
ULTIMATE PIT CONFIGERATION
EXTERNAL DUMPK
Hq
WORKING BENCH MINED OUT SPACE
WORKING BENCH
Hq Grade Control ULTIMATE PIT CONFIGERATION
ULTIMATE PIT CONFIGERATION
BERM
The mining operation is an integration of number of tasks arranged in sequence. These are often referred to as unit operations. Site preparation, Drilling and blasting, Excavation and Loading, Transportation, Stock Piling or Spreading and Reclamation are such unit operations required to be carried out as surface mining unit operations. There are numerous ways of performing these tasks. These methods depend on the characteristics of deposits, expected rate of extraction and life of the mine, scheme of completion of the unit operations. Table 1 shows the main unit operations that are sequentially carried out in a surfac e mine. Following a system approach the operations mentioned in
Table 1 are carried out and thus the whole opencast mining can be considered as comprised of well defined unit operations or mining subsystems. Each of these subsystems is characterised by the type of equipment deployed and subsequent methodology followed. The selection of equipment and design of work organisation are dependent on the characteristics of the deposit, market demand and available technological know-how.
Table 1 Operations at different phases of surface mining. Phases
Preparation
Construction phase
Development phase
Operations Clearance of wood Timber felling and stumping Drainage network construction Top-soil excavation and storage Infra-structure development Construction of erection yard Approach road construction Electricity supply system construction Temporary and permanent building construction
Removal of overburden Drilling Blasting Excavation Loading Transportation Dumping Dump yard construction Levelling Environmental Protection Measures Infrastructure Development Overburden removal Mineral/ore excavation Drilling Blasting Excavation Loading Transportation Storage Reclamation (Work is similar to construction phase with additional machinery and more work loads)
Exploitation phase
As in Development Phase. However, full set of machinery is deployed for targeted production.
Reconstruction phase
Replacement of old machines or technology
Extinction phase
Restoration of site for alternative uses
Types of Surface Mines and Quarries Depending on the geo-technical and economic consideration surface mines and quarries are operated by various ways. Figure 2 shows various types of surface excavations. Surface type of mining is suitable for horizontal or gently dipping deposits, placer deposits and stone quarries. Deep-surface type of mines is more practical in mining ore deposits and steeply dipping coal deposits. These mines may be as deep as 800 metres. On-slope type surface mining is applicable for deposits lying at a level higher than the prevailing surface level. Some deposits lie under the river bed, sea bed or lake bed. The mining type used in these cases is under-water type of mining. Each of these methods deploys different set of machinery. Figure 3 shows examples of surface mining using different machinery. Vast mines are characterised by depth up to 100 metres and occupying a large surface area. The elongated mines are characterised by larger dimension along the strike length several times larger than the dimension across the strike length. For columnar type of deposits and for deep deposits rounded mines are constructed. Rzhevsky (1985) classified opencast mines as shown in Table 2. Continuous mining is a system of mining in which there is no time delay between extraction and loading and loading and transport. The excavation continues without stopping and loading to the transport system is done simultaneously. For example when a bucket wheel excavator is continuing to excavate loading to the conveyor is also simultaneously done. However, in a shovel operation the shovel does not excavate while the bucket is carrying the excavated material to load on a dumper. That is why the shovel-dumper system is not a continuous system but a BWE-conveyor is a continuous mining system.
TYPES OF SURFACE EXCAVATION Surface Excavation
Position
e s e p p e y p y y T T T e e e c p c a a l o f r f S u r u n S S O p e e D
Shape and Size
e p t y s a T r V e t a W r e d n U
d e t a g n o l E
d e d n u o R
Mining Method
s u o u n i t n o C
Figure 2 Types of surface mines
c i l c y C
n o i t a n i b m o C
Figure 3 Different types of surface excavation
Table 2 Classification of opencast mines (Rzhevsky, 1985). Field Size
Very small Small
Type of OCM
Open pit Area (Km2)
Open- Pit Depth (m)
Surface
up to 0.4
up to 20
On-Slope
up to 0.3
up to 40
Surface
0.4 ---- 2.0
up to 40
On-Slope and
0.3 ---1.5
40 ---100
Surface
2.5 --- 6.0
up to 60
On-Slope and
1.5 ---5.0
100 --- 200
Surface
4 --- 20
up to 80
On- Slope and
4 --- 12
100 --- 250
Volume of Rock(m3)
Quarry Life (Years)
up to 10
up to 10
10 ------ 100
10 ---- 25
100 --- 500
25 --30
500 --- 2000
30 --- 60
Deep Medium
Deep Large
Deep Very Large
Surface
10 ---40
up to 120
Deep
10 --- 30
200 ---800
2000 ---10,000
Common Types of surface mining methods include 1. 2. 3. 4.
open pit mining quarrying, glory holing strip mining placer mining.
1. Open pit mining is a surface mining method in which nearly all of the deposit and ore is removed in terrace-like working areas on the side of a pit. Grade and tonnage of materials available determine the size and limits of the pit developed as well as the size and configuration of waste rock dumps. In this type of mining, it is often necessary to blend different ore types to maintain character and grade of the mill feed, or different types of ore (i.e., oxide verses sulfide and low-grade ore) may need to be managed and processed differently (Lacy, 1999). Oxide and sulfide ores require different types of beneficiation and processing, and some low-grade oxide ores may be processed in a leach pad facility. Open pits are often closed or reclaimed by simply allowing the pit to develop into a pit lake and waste rock dumps are usually closed and reclaimed in place.
2. Quarrying is similar to open-pit mining, however, it is usually restricted to mining dimension stone or prismatic blocks of marble, granite, limestone, sandstone, etc.
3. Surface Glory Hole method is generally performed on hillsides and often used to define irregular deposits of the surface. The method has a mine o pening at the surface and ore is removed by gravity through raises connected to adit haulage ways. Ore is transported to the surface or side-hill using tramways (Lacy, 1999). This method generally results in smaller volumes of waste rock removed and deposited in surface dumps.
4. Strip mining is surface mining where reclamation is contemporaneous with extraction. It is applicable to shallow, flat-lying deposits of coal, oil-shale, clay, sand, gravel, and some uranium, phosphate and placer deposits. As the overburden is removed from one portion of a mineral deposit, it is used to fill in the trench left by the previous removal. In this manner, the overburden is continuously refilled to the adjacent previously mined area and reclaimed.
5. Placer mining is a method for the recovery of heavy minerals using water to excavate, transport, and or concentrate the mineral being mined (Lacy, 1999). Placer methods vary greatly depending on the size and characteristics of the deposit being mined. However, placer mining in general, usually affects large areas because the ore bodies are in large alluvial deposits with low-grade, but a high volumes of mineral. The method can be highly visible and create large areas of disturbance. Many historic placer operations created serious impacts to stream channels, hydrologic systems and aquatic habitats.
Ref: http://www.epa.gov/ORD/NRMRL/Pubs/600R01043/600R01043AppA.pdf
Classification of Surface Mining Systems. Classification of mining systems may be based on different operational features. Systems with machines capable of excavating continuously and loading the excavated material simultaneously to a means of continuous transport are known as continuous mining system. Bucket Wheel Excavator (BWE) with belt conveyor is such a system. Direct hydraulicking of soft solid without ground preparation is also in this category. All other mining systems are non-continuous mining system. Systems with shovel and truck or excavating with dragline follows a definite working cycle. That is why such systems are also referred as cyclic system. Based on the mode of movement of excavated material surface mining systems can be transportless or direct casting type. Mining with dragline or stripper shovel falls under this category.
In the semi-continuous system the excavation is carried out by conventional non-continuous or cyclic machine but the transportation is by belt conveyors. Figure 4 shows the classification of surface mining system. SURFACE MINING
TRANSPORT-LESS
WITH TRANSPORT MACHINES
•
DRAGLINE
•
STRIPPER SHOVEL
CONTINUOUS
BUCKET WHEEL EXCAVATOR
NON-CONTINUOUS
SEMI-CONTINUOUS
SHOVEL-BELT CONVEYOR
SHOVEL-TRUCK FRONT END LOADER-TRUCK
BUCKET CHAIN EXCAVATOR DREDGER
Figure 4 Classification of surface mining system. Mining system may also be classified based on method of face advance. There are two principal methods applicable to stratified deposits, which may be applied separately or in combination. One is the parallel advancing of faces called as parallel advance system. The other is pivotal advance system. In the former transport arrangements are to be advanced at regular intervals, while in the latter, permanent transport arrangements from the pivot i s easily arranged.
A surface mine being highly mechanised the performance of any mining venture depends mainly on the selected equipment for the system. Table 3 shows the equipment complexes in different unit operations of various opencast mining systems. Table 3
Equipment complexes in different unit operations of various opencast mining systems. Unit Operations
Systems Cyclic
Drilling and
Excavation and
Blasting
Loading
1. Drill
Electric Shovel
Transport Dump Truck
Storage and
Auxiliary
Dumping
Equipment
Dozer
Dozer, Crane, Grader
Semi-Cyclic
2. Drill
Hydraulic Shovel
3. Drill
Dragline
1. Drill
Shovel,
Dump Truck --------Conveyor Belts
Mobile Crusher
Dozer
Do
------Do-----
Do
Tripper,
-----Do-----
Spreader, Dozer
2. Drill
Shovel,
Dumper and
-----Do----
Conveyor Belt
-----Do----, Semi-Mobile or In-Pit Crusher,
Continuous
1. Drill
Tripper,
Dozer, Track-
Excavator, Mobile
Bucket Wheel
Spreader,
Shifter, Crane,
Transfer
Dozer,
Grader, Mobile
Conveyor,
Reclaimer
Crusher
Transfer Feeder
Conveyor Belts
2. Drill
Bucket Chain
------Do----
-----Do----
----Do----
-----Do-----
-------Do----
------Do----
Excavator 3. -------
Continuous Surface Miner
Surface Mining Operations Surface mining operations involve the following operations: 1. Performing basic earth moving operations: The loose or loosened earth materials or broken rock mass are separated from the massif and moved for further handling. The basic earth moving operations are carried out during site preparation as well as during production and site restoration. These operations include dozing, ripping, l evelling, spreading, stacking etc. a.
Operations with dozers
b. Operations with scrapers 2. Haul road construction and maintenance operations a.
Operations with motor graders
b. Operations of compactors c.
Operations of water truck for haulroad dust control
3. Drilling and blasting operations : To produce broken rock mass from the insitu rock blast holes are drilled for placing explosives to blast the rock. Surface mining involves blasting of the overburden or waste rock and the minerals or coal separately ensuring that the grade of the ore is not diluted by mixing of more overburden with the ore or loosing ore with the overburden. 4. Operations of excavators: The loosened rock mass is excavated by using excavators suitable for the operations under the site specific geo-mining conditions and production requirements. Different systems used in surface mining include:
a. Operations with electric rope shovel b. Operations with hydraulic excavators and back hoe c.
Operations with front end loaders
d. Operations with dragline e. Operations with bucket wheel excavators f.
Operations with bucket chain excavators
g. Operations with surface miner h. Operations with auger miner i.
Operations with high wall miner
5. Transporting operations in surface mines a. Bulk material transport by truck b. Conveyor operations: shiftable, mobile and slew conveyors c.
Bridge conveyor operations
d. Slurry transport operations
6. Dewatering operations in surface mines 7. Stacking and reclaiming operations 8. Operations for dump formations
Mining Industry in India India is one of the important mineral producing country in the world. Mining industry in India plays an important role in Indian economy. Production and use of minerals in India has a very old history. Coal, iron-ore, copper, lead-zinc were mined in India from the dawn of civilisation and does not have any systematic records. Records of mining activities in India is found in the Kautilya’s
Arthasastra which indicates taxation on mineral produced in the 4
th
century. After India was
captured by the British, East India Company permitted a English Company to undertake mining operation at Raniganj Coal field in 1774. In 1880, M/s John Taylor & Sons Ltd. started gold mining in Kolar Gold Fields. Oil production started in India in 1866 and coal production in Makum Coal field of Assam started in 1882. Mining industry in India started developing in the 20
th
century and was
predominantly to serve the interest of the British Government. After independence, the mining industry is being continuously shaped to serve the National interest and welfare of Indian People. In 1971 coal mines were nationalised. Subsidy was given to the industry so that basic raw materials for Nation building could be made affordable. National investment for mining is planned in every Five Year Plans and the activities inn this industry are governed by National Mineral Policy, which has been recently modified to encourage more International investment and welfare generation in the country.
Surface Mining in India
India produces both fossil fuel and ores from surface mines. Number of surface mines are operating in different parts of India. A brief overview of the occurrence of mineral deposits are presented below:
Coal Deposits in India
Today’s coal mining in India exploits coal seams up to a depth of about 600m. However, coal seams
are available up to a depth of 1000-1200m. The mineability of these deeper seams is yet to be properly evaluated. The major coal f ields are discussed below:
Raniganj Coalfield This coalfield spreads in the states of West Bengal and Jharkhand. This is the easternmost field of the Damodar valley. It is a synclinal basin and its southern side is bounded by faults. It covers an area of 1550 sq km. The coal seams in this coalfield belong to Raniganj & Barakar formations (Table 1). There are 10 major coal seams in Raniganj formation, thickness ranging from 1-11m and 7 major seams in Barakar formation, thickness ranging from 1- 24m. The coal seams dip to the south at angles between 3˚- 11˚. In some places they are invaded by igneous sills and dykes and faults. Total in situ coal reserve of this coal field has been estimated as 22 Gt. The gas content is about 5 – 7 3
m /t. It covers an area of 1550 sq. km.The geothermal gradient v aries from 25 ˚C -52 ˚C for 1 km. Coal of Barakar formation is of coking type with low moisture and low to medium volatile mater content. Coal of Raniganj formation is non-coking type with high moisture and high volatile matter.
Table 1 Geologic succession of Raniganj Coalfield Age
Formation
Recent
River alluvium
Sub-recent
Laterite
Jurassic or Tertiary
Rajmahal traps or Deccan traps
Jurassic
Rajmahal traps or Earlier
Upper Triassic
Supra-panchet
Thickness ( m)
305
------------------UNCONFORMITY---------------Lower Triassic
Panchet formation
610
Upper Permian
Raniganj formation
1035
Middle Permian
Ironstone Shale
365
Lower formation
Barakar formation
610
Upper Carboniferous
Talchir formation
375
------------------UNCONFORMITY---------------Crystalline archaeans (basement rocks)
Figure 1 shows the geological map of this coalfield.
Figure 1 Geological sketch map of the Raniganj coalfield showing major structural features and various localities mentioned in the text. Note numbered squares denoting Poradih (1), Jemua (2), Jaideb (3) and Dishermohan (4) (S.C. Ghosh / Sedimentary Geology 147 (2002) 155 –176)
Subsidence is common phenomena in coal mining areas of this coalfield. The coal seams are of shallow depth. There are two sets of major faults with trends NNE-SSW in the Western part and NNW-SSE in the eastern part traverse the area. The latter one has better potential for ground water.
The Jharia Coalfield It is the most important coalfield in India with the sole deposit of the coking coal. It is situated in the heart of the Damodar valley along the north of Damodar River. It covers an area of 450 sq km in the state of Jharkhand. The coalfield is bound by major faults towards SSW direction. The stratigraphic succession at the coalfield is given in Table 2.
Table 2 Stratigraphic succession of Jharia Coalfield Age
Formation
Maximum thickness
Litho-type
Jurassic or Tertiary
Dolerite dyke
Lower Jurassic
Mica lamprophyre, dykes & sills
Upper Permian
Raniganj
Fine grained feldspathic sandstone, Shale with coal seams
800 m
Middle Permian
Barakar measures
Buff
730 m
coloured
sandstone,
Shale
&
carbonaceous shale Lower Permian
Barakar
Buff coloured sandstone, carbonaceous shales & coal seams
Grits,
Upper Carboniferous
Talchir
Greenish shale & fine- grained sandstone
1250 m 245 m
-----------------UNCONFORMITY------------------Archaean
Metamorphics (Basement complex)
The structure is a half graben bounded by major faults towards SSW direction. In this coalfield (Figure 2) there are a total of 42 coal seams present upto a depth of 1200m, which belong to B arakar formation (individual seam thickness varies from 0.3 – 33.0 m) and 10 – 20 coal seams are present in Raniganj formation (thickness varies from 0.1 – 4.7 m). It covers an area of 450 sq. km. The total 3
reserve estimated as 17 Gt. The gas content of these coal beds is estimated as 7 – 26 m /t.
Figure 2 Geological map of Jharia Basin, India The CBM production initiatives in this coalfield have successfully implemented to have the f irst CBM well in the country. These coal field is one of the oldest coalfields in India. The multiple seams occur to a greater depth ( Barakar formation).
Talcher Coalfield It covers an area of 1815 sq km in Orissa. Structurally it is a broad synclinal basin with a dip varying from 3˚ - 7˚. No igneous intrusion has taken place. The total reserve estimated is around 36 Gt with
huge quantity of inferior grade non-coking coal in thick seams, lying at comparatively shallow depths. The degree of faulting varies across the field. The coal seams belong to Karharbari (12 seams) & Barakar (1 seam) formation (Table 3). The thickness of the coal seams varies from 1- 60 m. Barakar formations are of low quality with high ash, high volatile and high moisture content. The total reserves were estimated 28 Gt in 1993. Structurally it is a broad syncline. The degree of faulting varies across the field. No igneous intrusion has taken place.
Table 3 Stratigraphic succession of the Talchir Coalfield Age
Formation
Recent
Upper Permian to Triassic
Lithology Alluvium & Laterite
Kamthi
Fine to medium grained sandstone, Carbonaceous shale, coal bands with greenish sandstone and pink clays
Barakar
Medium to coarse grained sandstone, Shale, coal Seams with conglomerate (500 m thick)
Karharbari
Medium to coarse sandstone, shale & coal seams (270 m thick )
Talchir
Dimictite, fine to medium grained green sandstone, Shale, Rhythmite (170 m thick )
Lower Permian
---------------------UNCONFORMITY--------------------Precambrian
Granite Gneisses, Amphibolites, Migmatites
A study conducted by CIMFR, Dhanbad based on their theoretical model and geological information estimated that there are 1017 Mt of unmineable coal reserve in this coal field and noted that the 3
average adsorption capacity of CO 2 is 20.4 m /t. The extension of coal beds below 1200m depth cover in coking and superior grade non coking coal have not been explored even though the continuity of the coal beds was well indicated within the lineament. The coal beds of such zones beyond mineable limit have been classed as Grey Area reserve. For the inferior grade non coking coal, the limit is 600m for Son Mahanadi Valley coal fields.
It has been reported that the grey area coal reserve in Talcher coalfield is 2.41 Bt and the cumulative coal seam thickness is 120 m.
There are 13 coal seams are occurred in this field with individual seam thickness vary from 1 to 80 meters with a cumulative thickness vary from 80 to 160 meters. A lot of f aults are present across the field with different orientations. Power grade non-coking coal is occurred here. Unmineable coalbeds are identified in this field below 600m depth. Proximate analysis of Talcher coalfield shows 35-45% of volatile mater and 79-82% of f ixed carbon ratio and 0.50-0.55% vitrinite reflectance. Figure 8.21 and 8.22 shows geological map and coal fields map of the area in Talcher coalfield. This area has been explored by GSI for the production of CBM.
Figure 8.21 Geological map of Talcher coal field showing explored area by GSI for CBM production (Web 21)
The Talcher coalfield is now explored by GSI under Indo-US collaboration programme for the production of coal bed methane (CBM) as and could be used in future for enhanced coal bed methane production using CO 2 injection.
Figure 8.22 Talcher coalfield map (Web 22) This coal field is of shallow depth without having proper caprock and thus not suitable for CO 2 storage.
Ib Valley Coalfield It covers an area of 1375 sq km in the state of Orissa. Structurally the coalfield is a half-graben bounded by large fault in the SW direction. Coal seams belong to Karharbari and Barakar formation. Coal seams belong to Karharbari & Barakar formations (Table 8.15). A total of 6-7 coal horizons (seams) are present. Thickness of coal seams under Barakar formation vary from 20 – 60 m with banded structure and high ash, high moisture and volatile content and therefore coal is of low rank. Seams under Karharbari formation are 1 – 7 m thick and are of better quality. Total reserve estimate was 22.23 Gt in 2002 ( IPICOL, 2002).
Table 8.15 Stratigraphic succession of the Ib Valley Coalfield Age Recent
Formation
Lithology Thick alluvium, laterite, recent gravel & Conglomerate bed
Upper Permian
Kamthi
Conglomerate, Fe-sandstone, Red shale ( 300 m thick )
to Lower Triassic
Barakar
Fine sandstone with conglomerate bands, Carbonaceous shale, Fine clay, coal seams (600 m thick)
Karharbari
Coarse grained sandstone with 1 thin coal seam (90 – 125 m thick)
Talchir
Dimictite, greenish sandstone, olive chocolate colored needle shaped rhythmite ( 130 m)
Lower Permian
---------------------UNCONFORMITY--------------------Precambrian
Granite Gneisses, Amphibolites, Migmatites
Figure 8.23 gives the geological map of this coal field.
Figure 8.23 Geological map of Ib-Valley coalfield (Web 23) This coalfield is overlaid by formation with conglomerate which will not be suitable for limiting any upward movement of pressurized gas if injected underneath.
Singrauli Coalfield This coal field is located in the northern Madhya Pradesh near to the Ganga Basin. High capacity thermal power stations are located in this coal field. The area has number of large point sources of CO2. However, the sequestering capabilities are not yet fully established. Figure 8.24 shows a geological map of the area showing large number of fault lines.
Figure 8.24 Geological map of Singrauli coalfield (Web 24) This coalfield is situated on the border of Uttar Pradesh and Madhya Pradesh and covers an area of 2
about 2300 km . Most part of the coalfield lies in M.P. while a small part of it is situated in the Mirzapur district of U.P. The coals of this field are of non coking type. The total coal reserve of this field 12.41 Bt. The Barakar and Raniganj formations are the coal bearing measures. Dolerite dykes and sills are invaded in the west and south of the basin. The faults are very rarely present even these are along the boundary. The dips of the strata vary from 2˚ to 5˚.
Stratigraphy The stratigraphic succession of the Singrauli coalfield has written in Table 8.16.
Table 8.16 Stratigraphy of Singrauli Coalfield. Age
Group
Formation
Recent Upper Permian
Lithology Alluvium
Damuda
Raniganj
Fine grained sandstone, shales, carbonaceous shales, white to grey clays, with thick coal seams
Middle Permian
Barren Measure
Very coarse grained to ferruginous sandstones, shales with red green clays
Lower Permian
Barakar
Medium to coarse grained sandstones, shales, carb, shales, white to pink clays, and coal seams
Upper carboniferous
Talchir
Tillite, sandstones, needle shales, siltstones, boulder conglomerates
………….Unconformity…………..
Precambrian
Bijawar
Phyllite, quartzite, schists and gneisses
Pranhita-Godavari Valley Coalfield 2
The Godavari valley coalfield comprises of 16000 km area extends over a length of about 320 km with an average width of about 55 km. The total coal reserve in this coalfield are estimated as 8.5 Bt of which 2.129 Bt is under proved category. It is a bituminous coal bearing coalfield in India. The Gondwana sediments attain a thickness of more than 3000 m. Linear and discontinuous patches of coal measures are occurred in this Godavari rift basin. The coalfield consists of numerous faults e.g. strike fault, oblique fault or dip fault etc. The general trend of the coal measures is NW-SE with dips varying from 10˚ to 25˚ in NE direction except some places. In this coalfield, Barakars and Kampthi
formation are coal bearing formation. The coalfield is devoid of igneous intrusion. The Barakar formation contains 3 to 10 coal seams out of which 2 to 4 seams are of considerable thickness. The thickness of the coal seams varies from few centimetres to as much as 30 m. The coals are noncoking, high moisture, high ash and high volatile type. The lower seams are of better quality than the upper seams. (R. D. Singh, Principles and Practices of Modern Coal Mining) . The stratigraphy of this coalfield has shown by Table 8.17 below. Figure 8.25 shows the geological map o f this coalfield.
Table 8.17 Stratigraphy of Pranhita-Godavari valley coal field (Modified from Sengupta, 2003 and Chandra, 2000)
Age Holocene
Upper Cretaceous Upper JurassicLower Cretaceous Lower-Early Jurassic
Formation
Lithology
Alluvial sand and clays
Thickness(m) 25+
…….Unconformity…
Deccan Tap
65
……..Unconformity….
Chikiala Sandstone …….Unconformity………
Kota ………Unconformity…
Conglomerates and ferruginous sandstone
300
Sandstone, Siltstone, Clays, Limestone bands
675
Middle-Upper Triassic
Maleri
Red or purple clays and sandstone
1000
Upper PermianLower Triassic
Kamthi
Sandstone, ferruginous, purple siltstone, coal
600
Upper Permian
Barren Measures
Sandstone, Ironstone and clay bands
500
Upper part of Lower Permian Lower Permian
Upper Proterozoic
Lower Proterozoic
Archaean
Barakar Talchir …….Unconformity……
Sullavai ……Unconformity………
Pakhal …….Unconformity……….
Granites, Banded gneisses, Biotite gneisses, Hornblende gneisses, Quartz magnetite schist, Biotite schist, Quarz and pegmatite veins
Feldspathic sandstone, Carbonaceous shale and coal
300
Tillite, Greenish shale
350
545
3335
Figure 8.25 Geological map of the Pranhita –Godavari Valley (Source: S. Sengupta, Gondwana sedimentation in the Pranhita –Godavari Valley: a review, Journal of Asian Earth Sciences 21 (2003) 633 –642
Risk associated As the coals in this field occur in fo rm of discontinuous patches, so it is difficult to identify a suitable potential site. The presence of numerous different type of faults make the probability of leakage occurrence is more. Though faults can be proved as suitable traps for sequestration, In that case also a greater monitoring and verification is needed for leakage.
Korba coalfield The Korba coalfield situated around Korba town of Madhya Pradesh state. It occupies an area of 2
about 520 km . The coal reserves in Korba coalfield is estimated as 10,000 Mt. The coal in this field is of sub-bituminous non-coking type of coal. The Barakar formation is the coal bearing measureswhich overlies the Talchir formation. The lithology of Barakar formation consists mainly of sandstone, shale and coal seams. The thickness of the Barakar formation is more than 800 m. The general strike of the rocks of Barakar formation is E-W and beds dip to the south below 10˚. There are 21 coal seams are occurred in this coalfield out of which nine seams are belong to lower barakarwith individual seam thickness are less than 4 m. But the upper Barakar formation consists of thick seams with a thickness range from less than one meter to over 30 meter than the lower Barakar formation (Chandra, 2000).
East Bokaro coalfield The Bokaro coalfield is situated in Hazaribagh and Giridih districts of Jharkhand state extends over an 2
area of 237 km . The total coal reserve in this field is about 5.6 Bt. Out of which 2.8 Bt of coal occur below 300 m depth.. This coalfield has been divided into two distinct zones namely East Bokaro coalfield ansd West Bokaro coalfield by the Lugu hill. The East Bokaro coalfield is the eastern zone of the main Bokaro coalfield. A number of faults are are traversed across the coalfield. Igneous intrusions are invaded into the coalfield. There are 21 coal seams in Barakar and 8 coal seams in Raniganj formation are present. Total coal reserve was estimated at 5.6 Gt in 1993. The coal seams of East Bokaro coalfields are bituminous to sub-bituminous in nature with high gas contents. So these seams have potential for CBM. The maturity of gas contents increases with increasing depth due to increase in temperature and pressure conditions. It has experienced igneous intrusions like dykes, sills & faults. Three coal bearing formations are present. These are i.
Karharbari formation consisting of 4 seams
ii.
Barakar formation consisting of 21 seams
iii. Raniganj formation consisting of 8 seams
Stratigraphy The stratigraphy of the East Bokaro coalfield is shown in the Table 8.18. The deep lying sedimentary strata may have sequestration potential and should be investigated in detail.
Table 8.18 Generalized stratigraphic succession of the East Bokaro coalfield (Pophare et al., 2008)
Age
Formation
Lithology
Lower Cretaceous
Intrusive
Lamprophyre and dolerite dykes and sills
Supra-Panchet
Coarse grained ferruginous sandstone, pebbly sandstone and red clay
Upper Triassic
Thickness (m)
600
..…Unconformity……
Panchet
Greenish micaceous sandstone, buff fine-grained sandstone, red and green shale
500-600
Raniganj
Medium to coarse grained calcareous sandstone, fine grained greenish sandstone, grey shale, carbonaceous shale and thin coal seams
600
Barren Measure
Flaggy, fine grained ferruginous sandstone, micaceous sandy shale and black shale with siderite band
500
Lower Permian
Barakar
Coarse grained arkosic sandstone, fine grained laminated sandstone, grey shale, carbonaceous shale and coal seams
900
Upper Carboniferous to Lower Permian
Talchir
Tiliite, greenish sandstones and needle shale
Lower Triassic
Upper Permian
Middle Permian
…..Unconformity…...
Pre-Cambrian
Granite gneisses, amphibolites and mica schist
Figure 8.26 shows the geological map of this coal field.
Figure 8.26 Geological map of the East Bokaro coalfield (Pophare et al., 2008)
Detailed site evaluation of the coal beds would be necessary to establish their candidature, because following features make these formations unsuitable for sequestration. 1. The site location is within the moderate seismic zone and is adjacent to the high seismic zone in the north. 2. Mining activities in the overlying seams may induce cracks and fissures in the cap rock of the underlying potential CO2 storage coal beds 3. The deeper seams are yet to be designated as Unmineable Therefore, future initiatives for exploitation of coal bed methane need to be investigated prior to establishing the storage potential. The permeability, porosity, injectivity, storage ca pacity as well as the geochemical properties etc needs to be evaluated.
The resources reported by GSI and other agencies have been classed as mineable and unmineable on the basis of the following factors (Singh and Sinha, 2007).
Exploration limit of coal has been to 1200m depth cover.
Coking and superior grade non coking coal up to the explored limit has been classed as mineable.
Inferior grade non-coking coal (Grade E-G) up to 900m depth cover in Damodar and Mahanadi Valleys have been taken as within mineable limit.
Mineable limit for inferior grade non coking coal of Godavari and Wardha Valleys have been taken as 800m due to premium pricing structure.
More scientific study and detailed analysis would be necessary to designate these seams as unmineable. Future development of technology, pricing, alternative exploitation techniques will have to be considered in such studies.
Neyveli Lignite Field This is one of the lignite deposit in India with a total reserve 3300 Mt. The lignite field covers an area 2
of more than 480 km . Within the lignite field the overburden thickness varies from 45 to 150 m and the thickness of the lignite bed varies from 2 to 20 m and it is persistent throughout the field.
Stratigraphy The stratigraphic succession of Neyveli lignite field is summarized in Table 8.19. (Source: Modified from Geology and tectonics of India: an overview, M. N. Balasubrahmanyam; and D. Chandra et al., Text Book of Coal (Indian Context), 2000, Tara Book Agency Publisher, Varanasi) Figure 8.27 and Figure 8.28 shows the map of the site and the cross section of the area.
Table 8.19 Stratigraphy at Neyveli Lignite field Age
Formation
Sub-Recent to Recent
Mio-Pliocene
Cuddalore formation
Lithology
Thickness (m)
Alluvium or soil
37
Mottled sandstone and clay
20-140
Lignite
0.2 - 28
Aquifer sand
376
………………………….. Unconformity…………………..
Eocene to Oligocene
Neyveli formation
Black clays or shales, grey coloured sandstones, calcareous sandstones, shales and siliceous limestones with fossils
…………………………Unconformity………………………..
Mesozoic
Cretaceous
Shell limestones, siliceous limestones, marls etc.
………………………Unconformity……………………
Archaean Intrusives
Dolerite, pegmatites, quartz veins, granitoid gneisses
Figure 8.27 Geological plan of Neyveli lignite field (Web 25)
Risks Associated Semi-confined and confined aquifers are occurred above and below the lignite bed and so there will be contamination. Moreover, the deeper strata must be evaluated for its potential retention capacity. There is no suitable cap rock above the lignite deposit, thus adsorbing CO 2 on lignite seams will not be feasible.
Figure 8.28 Geological cross-section along one mine in Neyveli lignite field (Web 26)
Wardha Valley coalfields The coalfield is situated in the Valley of Wardha River lying in the Chandrapur district of Maharastra. 2
The coalfield extends in NW-SE direction covering an area of 4130 km .The coals of this coalfield are non coking type of coal. The coal bearing Barakar formation are 76 m thick and occur in patches. The estimated reserve of this coalfield 5.7 Bte, out of which 4020 Mt occurred above 300 m from the ground.
Stratigraphic Succession The generalized geological succession of the Wardha valley coalfield is given as follows in Table 8.20. Geological map is shown in Figure 8.29.
Figure 8.29 Geological map of Wardha valley coalfield (Web 27) Table 8.20 Stratigraphy of Wardha Valley Coal field(reference) Age
Formation
Recent Eocene
Lithology Black soil
Deccan trap
Basalts
………….Unconformity…………
Upper Triassic Upper Permian to Lower Triassic
Maleri formation (Only in the southeastern extrimity
Fine to medium grained sandstone and red shales
Kamthi formation
Red, brown and variegated sandstones, reddish siltstones and variegated shales
……………Unconformity………………
Lower Permian
Barakar formation
Light grey to white sandstones, shales and coal seams
Lower carboniferous to Lower Permian
Talchir formation
Tillites turbidites, varves, needle shales and sandstones
……………Unconformity……………
Precambrian
Sullavai sandstones
White to light brown quartzitic sandstones, conglomerates
……………..…Overlap…………………
Precambrian
Grey, bluish or pinkish limestone and cherts
Pakhal limestone ………………Unconformity…………..
Archaean
Quartzites, Granites
Rajmahal coalfields There are five coalfields are occurred in this area extending for a distance of about 160 km in N-S direction from Suri. The coalfields of this basin are 1. B rahmani, 2. Mahuagarhi, 3. Pachwara, 4. Chuperbhita and 5. Hura. Brahmani coalfield lies in the southern side containing six seams varying in thickness from 1.4 to 1.9 m. The coal seams in Mahuagarhi are lens shaped with individual seam thickness as much as 10 m. There are ten coal seams have been reported in Pachwara coalfield.Chuperbhita coalfield contains 13 coal seams which are of inferior quality. There are 3 coal seams are present at Hura. At places the seam thickness attains 37 m. Coals of this region are subbituminous to high volatile bituminous in rank. The coal seams are trending W to E in the western part of the field, becoming WNW to ESE in the central part, gradually changing to NW to SE and even N to S in the eastern part.
Stratigraphy The stratigraphic sequence of Rajmahal basin is given in Table 8.21.
Table 8.21 Stratigraphic succession of Rajmahal basin (Tripathi, 2008) Age
Formation
Lithology
Recent to subrecent
Alluvium
Loose soil, silt and clay
Upper Tertiary
Coarse to medium grained sandstone, gravel, pebble beds ………………Unconformity………………
Lower Cretaceous
Rajmahal formation ( Traps and intertrappeans)
Flows of basalt, pitchstone, and intertrappean beds
Lower Cretaceous to Lower Triassic
Dubrajpur formation
Pebbly and coarse to medium grained sandstone, siltstone, clay, Grey to pink shale
…………….Unconformity……………..
Upper Permian Lower Permian
Coal, shale, sandstone Barakar formation
Coarse to medium grained and
pebbly sandstone, grey shale, clay and coal Talchir formation
Tillite, fine to medium grained sandstone, olive green shale
………………Unconformity………………..
Precambrian
Basement rock amphibolites, quartzite, gneiss and granite
Vindhyan Basin The geological map of the Vindhyan basin has shown in the Figure 8.30 .
Figure 8.30 Geologic map of the Vindhyan basin, central India (Bengtson et al., 2009 ) The depositional sequence of the Vindhyan succession has also given in the Figure 8.31.
Figure 8.31 Inferred depositional sequences of the Vindhyan succession. (Chakraborty, 2006)(Not to scale )
India’s major workable coal deposits occur in two distinct stratigraphic horizons - Permian, commonly known as “Gondwana” coals and the Tertiary. About 99% of the country’s coal resources are found
within a great succession of fresh water sediments. The major coalfields are represented by isolated basins which occur along prominent present day river valleys, viz., Damodar, Koel, Sone-Mahanadi, 2
Pench-Kanhan, Pranhita-Godavari. Nearly 50 coalfields, varying in size from a few km to as much as 2
1500 km are known today, barring the small and lenticular occurrences of coal along the Himalayan foothills. Coals of practically all ranks occur in India except peat and anthracite. The share of lignite, however, is insignificant as compared to sub-bituminous and bituminous coal. Indian bituminous coals are broadly divided into two categories, coking and non-coking. Coal exploration in India even today is largely being carried out by conventional methods of systematic geological mapping followed by drilling, core drilling playing a dominant role. However, in the recent times modern exploration techniques like photo-geology, remote sensing, non-coring drilling, geophysical surveys etc. are being increasingly used for detailed and precise exploration.
Coal Reserves
The total coal reserves of the country have been estimated from time to time. * Proved Reserves: In this case, the reserves are estimated from dimensions revealed in outcrops, trenches, mine workings and boreholes and the extension of the same for reasonable distance not exceeding 200m on geological evidence. Where little or no exploratory work has been done, and where the outcrop exceeds one km in length, another line drawn roughly 200m in from outcrop will define a block of coal that may be regarded as proved on the basis of geological evidence.
* Indicated Reserves: In the case of indicated reserves, the points of observation are 1,000 m apart,
but may be 2,000 m for beds of known geological continuity . Thus a line drawn 1,000 to 2,000 m from an outcrop will demarcate the block of coal to be regarded as indicated.
* Inferred reserves : This refers to coal for which quantitative estimates are based largely on broad knowledge of the geological character of the bed, but for which there are no measurements. The estimates are based on an assumed continuity for which there is geological evidence, and more than 1,000 to 2,000 m from the outcrop.
Statewise and depthwise Coal reserves are given in the following table,
In Million Tonnes State
0-300m
300-600m
600-1200m
Total
West Bengal
11999
8933
4191
25123
Bihar
40079
17626
6666
64371
Madhya Pradesh
32638
7433
14
40085*
4590
1686
-
6276
Maharashtra
Orissa
35015
11167
37
46219
5245
3876
1717
10838
710
155
-
865
130276
50876
12625
193777
67
26
7
100
Andhra Pradesh North Eastern Region Total Percentage
* includes 1062 Million. Tonnes in UP The following table gives the Statewise reserves indicating different categories, State
Proved
Indicated
Inferred
Total
Percentage of total reserve
West Bengal
10590
10867
3666
25123
13
Bihar
28993
28801
6579
64373
33
9387
20480
9156
39023
20
Uttar Pradesh
662
400
-
1062
1
Maharashtra
3170
1179
1927
6276
3
Orissa
5714
22120
18384
46218
24
Andhra Pradesh
6079
916
3843
10838
5
257
149
458
864
1
64852
84912
44012
193777
100
33
44
23
100
Madhya Pradesh
North
Eastern
Region Total Percentage
Thus, India’s total coal resources now stand at a level of a little over 194 billion tonnes in coal seams
of thickness 0.9m and above and upto a depth of 1200m. This is a little over 1% of the global coal resources. Of the total coal reserves of 1 94 billion tonnes, 85% is of non-coking variety and only 15% is of coking variety. Further, 33% of the reserves fall under ‘Proved’ category 44% in the ‘Indicated’ category and 23% in the ‘Inferred’ category. The coal occurring between 600m and 1200m depths, which may be economically tapped for development in future, may be grouped as “Resources” and the rest as “Reserves”.
Lignite Resources
The total lignite deposit of the country is estimated at about 2800 million tonnes, out of which the major deposit is occurring in Tamilnadu ( 2500 million tonnes). The remaining lignite deposits are found in Gujrat, Jammu & Kashmir and Rajasthan. Further exploration activities indicate availability of additional lignite resources in Rajasthan, Gujrat and Tamilnadu.
Indian coal mining and metal mining sector both have large number of opencast mines. There are 205 billion tonne of coal reserve in India of which 15% is coking coal. The reserve of lignite is estimated to be 27 billion tonne. Out of 571 coal mines in India there are 137 surface mines and 369 underground mines. There are 65 mines with both surface and underground operations.
The trends of coal production in India from underground and surface mines are shown in Table 4 and Figure 5.
Table 4 Trends of coal production in India from underground and surface mines. Year
Total
Opencast
Opencast
U/G
U/G
% by
(x1000 t)
(x1000 t)
OMS
(x1000 t)
OMS
Opencast
% by U/G
Overall OMS
1951
34983
4784
0.54
30199
0.59
13.67521
86.32479
0.35
1956
39911
4786
0.52
35125
0.64
11.99168
88.00832
0.39
1961
55709
10822
0.64
44887
0.68
19.42595
80.57405
0.45
1966
70387
13387
0.99
57000
0.76
19.01914
80.98086
0.56
1971
75642
17090
1.46
58552
0.86
22.59327
77.40673
0.67
1976
104639
28440
1.48
76199
0.91
27.17916
72.82084
0.69
1981
127325
51120
3.02
76205
0.82
40.14922
59.85078
0.81
1986
170159
95132
4.89
75027
0.77
55.90771
44.09229
1.01
1987
187179
111777
5.69
75402
0.78
59.71663
40.28337
1.11
1988
198349
122104
6.16
76245
0.79
61.56018
38.43982
1.19
1989
206947
133043
6.78
73904
0.77
64.28844
35.71156
1.23
1990
212741
143208
6.95
69533
0.73
67.31566
32.68434
1.26
1991
237757
167026
8.05
70731
0.73
70.25072
29.74928
1.4
1992
249941
178879
8.3
71062
0.75
71.56849
28.43151
1.47
1993
260607
186935
8.75
73672
0.77
71.73061
28.26939
1.57
1994
267522
196878
9.22
70644
0.77
73.5932
26.4068
1.63
1995
284586
216074
10.07
68512
0.78
75.92573
24.07427
1.8
1996
304097
233970
10.69
70127
0.8
76.93927
23.06073
1.91
350 300 ) t M ( 250
Total (Mt) Opencast Underground
n o 200 i t c 150 u d 100 o r P
50 0 1940
1950
1960
1970
1980
1990
2000
Figure 5 Trend of coal production in India. Besides coal about 22.2 Mt of lignite is produced in India from 5 lignite mines. Out of these 2 located at Neyveli in Tamilnadu provide 17.6 Mt of lignite per year. The rest 4.6 Mt come from 3 mines in Gujrat. India also produces iron ore and bauxite mostly from opencast mines. Figure 6 shows the output per manshift achieved in Indian coal mining. This shows that the OMS at opencast mines have been considerably improved. However, the OMS of underground mining have been continuously decreasing after 1988.
12 10 Underground OMS Opencas t OMS
8
S M6 O
Overall OMS
4 2 0 1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
Figure 6 Output per manshift (OMS) in Indian coal mining. In the metal mining sector opencast mining plays an important role in India. All our iron ore mining is from opencast mines. Bauxite mining is also purely surface mining.
History of Indian Surface Mining The share of surface mining in total coal production in India has continually increased from the 1960s. At the time of nationalisation it was only 25.4 % of the total coal production. In 1983-84 it was 45.4% and it is expected to be 65 % by 2000. First mechanised surface mining in India started during world war II at East Bokaro. In 1958 NCDC (National Coal Development Corporation) started opencast mining in their new areas such as Karanpura, East Bokaro, Chirimiri, Bisrampur, Korba and Talcher.
Table 5 List of some important opencast mining projects (Coal Mining) Sl. No
Names
Annual Capacity (Mt)
Average Stripping Ratio
Total Excavation 3
Total Capital Investment (1983
(Mm )
pricing, MRs) 1
Rajmahal
5.0
1.94
8.81
870
2
Sonepur Bazari
3.0
5.45
1137
1130
3
Jambad
2.25
7.00
472
1130
4
Mukunda
12.0
4.5
-
1300
5
Bina
4.5
2.21
309
1390
6
Dudhichua
10.0
3.29
1356
3410
7
Jayant
10.0
2.6
1132
3130
8
Khadia
10.0
4.28
1457
6550
9
Amlohri
4.0
4.30
1579
4370
10
Nigahi
14.0
3.75
2163
8360
11
Bharatpur
3.5
0.80
243
540
12
Rajarappa
3.0
2.91
456
1060
13
Gevra
10.0
1.0
1039
1730
14
Kusmunda
6.0
1.41
760
770
15
Manuguru
2.75
3.68
16
Ramagundam-I
2.0
3.36
17
Ramagundam-II
2.75
5.61
18
Piparwar 3 -1
The overburden to coal ratio in the earlier mines using truck and shovel was about 2 m t . In mines 3 -1
with draglines the ratio was 5 m t . With the increase in the size of equipment mines with larger stripping ratios were planned. Till mid 50s average over burden thickness was about 50 m in mechanised surface mines having shovels and dump trucks as predominant machinery. The thickness of coal seam in such mines was about 20 m with seam dip of 1in 6 to 1 in 12. At present in India there are opencast coal mines deeper than 100 m. Seam with gradient upto 1 in 3 are also being operated. There are number of mines in Jharia Coalfield and Singrauli Coalfield where opencast mining exploits multi-seams. Some opencast mines are opened over developed seams to excavate the abandoned coal locked in the partially exploited pillars, that is not operable by underground mines. Table 5 shows example of few of the major opencast projects of India. Except Piparwar all the mines listed above are cyclic in nature. Dragline and shovel are the primary mining machinery and dump trucks are used for coal transport. Lignite mining in India is an excellent example of India,s successful implementation of continuous surface mining. Piparwar is an example of semi-cyclic opencast mining. In this mine shovels carry out excavation and the transportation of the excavated material is by conveyor belts. Such system with inpit crushing is also being practiced at Padmapur (Western Coalfields Limited, WCL) and Ramagundam (Sigarenni Collieries).
COAL RESERVES IN INDIA (As on 1.1.2007)
(in billion tonnes)
.
TOTAL
PROVED
INDICATED
INFERRED
COKING
NONCOKING
TOTAL
RESERVE
RESERVE
RESERVE
RESERVE
32
17
13
2
255
98
119
36
287
115
132
40
Production RAW COAL PRODUCTION (in Million Tonnes)
OFFTAKE OF COAL (in Million Tonnes)
DESPATCH TO POWER SECTOR (in Million Tonnes)
OVERBURDEN REMOVAL
MAN PRODUCTIVITY
MAN POWER (As on)
Growth & Production (In Million Tonnes) Terminal Year
Five Year Plan
Avg. Annual Growth
Production
over previous year.
(India)
1955-56
First
6.95
38.13
1960-61
Second
4.00
55.72
1965-66
Third
0.93
67.74
1973-74
Fourth
7.52
78.17
1978-79
Fifth
6.28
101.97
1984-85
Sixth
6.38
147.43
1989-90
Seventh
5.16
200.91
1996-97
Eighth
7.74
285.66
2001-02
Ninth
4.19
327.79
Companywise Production
Company ECL
7475
84-85 94-95
2001-02
2002- 2003- 2004- 2005- 200603
04
05
06
07
U/G
20.50 16.67
13.61
11.66
10.95
9.91
9.45
9.34
8.27
O/C
2.66
6.44
11.24
16.89
16.23
18.09
17.80
21.78
22.20
Total
23.16 23.11
24.85
28.55
27.18
28.00
27.25
31.11
30.47
U/G
15.64 13.34
11.49
7.59
7.29
6.74
6.38
5.47
4.90
O/C
2.10
8.50
17.26
17.66
16.86
15.94
15.94
17.84
19.30
Total
17.74 21.84
28.75
25.25
24.15
22.68
22.32
23.31
24.21
U/G
5.97
5.48
4.01
2.74
2.76
2.75
2.65
2.31
1.96
O/C
12.34 33.52
27.19
31.07
34.22
34.58
34.74
38.20
39.36
Total
18.31 39.00
31.20
33.81
36.98
37.33
37.39
40.51
41.32
32.50
42.46
45.10
47.03
49.95
51.52
52.16
BCCL
CCL
NCL O/C
-
-
WCL U/G
15.73 24.57
9.60
9.49
9.39
9.51
9.65
10.04
9.92
O/C
3.53
21.48
17.64
27.52
28.43
30.02
31.76
33.17
33.30
Total
19.26 46.05
27.24
37.01
37.82
39.53
41.41
43.20
43.21
SECL U/G
-
-
14.55
15.91
16.16
16.36
16.58
16.52
16.20
O/C
-
-
35.45
48.21
50.44
54.65
61.97
66.50
72.30
Total
-
-
50.00
64.12
66.60
71.01
78.55
83.02
88.50
MCL
U/G
-
-
1.94
1.65
1.76
2.05
2.18
2.02
1.97
O/C
-
-
25.39
46.16
50.47
58.00
63.90
67.59
78.03
Total
-
-
27.33
47.81
52.23
60.05
66.08
69.61
80.00
U/G
0.38
0.44
0.40
0.18
0.11
0.12
0.15
0.12
0.11
O/C
0.14
0.37
0.79
0.46
0.52
0.61
0.48
0.98
0.94
Total
0.52
0.81
1.19
0.64
0.63
0.73
0.63
1.10
1.05
U/G
58.22 60.50
55.60
49.22
48.42
47.44
47.04
45.82
43.32
O/C
20.77 70.31 167.46
230.43
242.27 258.92 276.54 297.57 317.59
Total
78.99 130.81 223.06
279.65
290.69 306.36 323.58 343.39 360.91
NEC
COAL INDIA LTD.
Overall CIL
OBR (MCum)
2006-07 2005-06 2004-05 2003-04
OMS (Tonnes)
537.65 533.95 516.11 496.90
3.54 3.26 3.05 2.82
MINERAL INFORMATION
ALL INDIA DISTRIBUTION OF MINING LEASES (AS ON 31/3/2005) MINERALWISE | STATEWISE
MINERALWISE Sl.No.
Mineral Code
Mineral
No. of Leases
Lease Area (hect.)
1
01
AGATE
2
45.58
2
65
AMETHYST
5
40.64
3
03
APATITE
1
13.29
4
04
ASBESTOS
39
1846.89
5
05
BALL CLAY
40
1976.19
6
06
BARYTES
128
2542.09
7
07
BAUXITE
289
26531.07
8
08
CALCAREOUS SAND
14
151.75
9
09
CALCITE
63
1627.34
10
10
CHALK
167
677.99
11
67
CHINA CLAY
412
17774.31
12
11
CHROMITE
30
9163.70
13
12
CLAY (OTHERS)
44
945.33
14
14
COPPER ORE
18
10747.16
15
16
CORRUNDUM
12
145.41
16
17
DIAMOND
2
576.51
17
18
DIASPORE
11
80.11
18
19
DOLOMITE
454
17575.85
19
82
DUNITE
1
4.45
20
69
EPIDOTE
1
5.00
21
21
FELSITE
4
80.79
22
22
FELSPAR
184
5196.12
23
23
FIRECLAY
240
16676.52
24
24
FLUORITE
18
1807.41
25
26
GARNET
83
1899.80
26
27
GOLD
10
6702.62
27
28
GRAPHITE
137
4792.00
28
29
GYPSUM
52
17853.27
29
86
IOLITE
8
76.97
30
30
IRON ORE
505
78238.44
31
31
JASPER
5
211.70
32
33
KYANITE
30
3170.50
33
75
LATERITE
131
1463.48
34
34
LEAD & ZINC ORE
13
8225.18
35
36
LIME KANKAR
24
891.14
36
37
LIMESHELL
29
3752.89
37
38
LIMESTONE
1544
113376.15
38
39
MAGNESITE
29
2546.06
39
40
MANGANESE ORE
231
22313.54
40
41
MICA
249
7816.08
41
42
MOULDING SAND
45
898.40
42
44
OCHRE
107
3439.06
43
72
OPAL
1
200.00
44
81
PERLITE
1
144.65
45
46
PHOSPHORITE
15
3490.57
46
47
PYRITES
1
647.50
47
48
PYROPHYLLITE
86
2835.99
48
85
PYROXENITE
8
78.70
49
49
QUARTZ
909
12817.61
50
50
QUARTZITE
59
757.48
51
87
ROCK PHOSPHATE
1
2.20
52
51
ROCK SALT
3
53.86
53
52
SAND (OTHERS)
49
4940.64
54
77
SHALE
30
408.54
55
54
SILICA SAND
483
20205.90
56
55
SILLIMANITE
5
9945.84
57
56
SLATE
17
868.47
58
58
STEATITE
426
20736.83
59
60
TIN
60
62
VERMICULITE
61
63
WOLLASTONITE
Sum
7
128.83
11
212.55
4
202.49
7527
472577.43
STATEWISE
1567
Lease Area (hect.) 54634.12
ASSAM
11
981.33
BHR
BIHAR
10
2030.16
4
CHG
CHHATISGARH
294
26406.26
5
GOA
GOA
250
18165.99
6
GUJ
GUJRAT
1094
23783.54
7
HPR
HIMACHAL PRADESH
60
1998.70
8
HRN
HARYANA
142
15267.21
9
J&K
JAMMU & KASHMIR
19
730.35
10
JHK
JHARKHAND
331
36990.92
11
KAR
KARNATAKA
425
38627.29
12
KRL
KERALA
108
2213.44
13
MAN
MANIPUR
2
610.17
14
MEG
MEGHALAYA
14
1660.16
15
MPR
MADHYA PRADESH
758
19536.80
16
MSH
MAHARASHTRA
252
17154.41
17
ORI
ORISSA
447
77410.59
18
RAJ
RAJASTHAN
1088
103913.78
19
SKM
SIKKIM
4
86.00
20
TMN
TAMIL NADU
435
6292.91
21
UPR
UTTAR PRADESH
93
9424.33
Sl.No.
State Code
State
1
APR
ANDHRA PRADESH
2
ASM
3
No. of Leases
22
UTL
UTTARANCHAL
70
3079.72
23
WBL
WEST BENGAL
53
11579.25
7527
472577.43
Sum
The trend of productionof Iron Ore in India is shown in Table 6 and Figure 7.
Table 6 Trend of iron ore production in India. Year Production (Mt)
1951
1971
1991
1994
1995
1996
3.7
33.0
60.0
65.0
73.0
71.6
80
) t 70 M ( 60 n 50 o i t 40 c u 30 d 20 o r P 10
0 1940
1950
1960
1970
1980
1990
2000
Year
Figure 7 Trends of production of iron ore in India.
6
) t 5 M (
5.35 4.7
n 4 o i t 3 c u d 2 o r 1 P 0 1940
3.86
1.45
0.05
1950
1960
1970
1980
1990
2000
Year
Figure 8 Trend of production of bauxite in India. India exports about 32 Mt of iron ore every year mainly to Japan and South Korea. Figure 8 shows the trend of bauxite production in India.
The National Aluminium Co. (NALCO) is the main producer of bauxite in India. The bauxite production is expected to go up in the country with the capacity enhancement of Panchpatmali Mines (NALCO) from its existing 2.4 Mt capacity to 4.8 Mt capacity. Figure 9 shows production of some other minerals in Indian surace mines during 1996. Besides these there was 120 Mt of limestone produced by surface mining in India during 1996.
5
4.75
4.5 4 ) t 3.5 M ( 3 n o i t 2.5 c u d 2 o r P 1.5
2.06
0.72
1 0.5 0 Copper
Gelena and Sphelarite
Granite
Figure 9 Production of minerals from surface mines in 1996 (Mt).
1000
s l e v o h S f o r e b m u N
500 450
900
400
0 350 0 0 1 300 x 250 P H 200
800 700
Number of Shovel
600
HP x 1000
500
150
400
100 1989
1990
1991
1992
1993
1994
1995
1996
Figure 10 Trend of deployment of shovels in surface coal mines.
Usage of Opencast Machinery As mentioned earlier Indian surface mining is mainly cyclic in nature. With the increase in demand from surface mining, the machinery populations have also increased. The installed horsepower has also increased about 1.5 times during the last ten years. Figures 10-14 show the trend of population increase of shovel, dumper, dozer and dragline in Indian coal mining.
1000
500 450
900 s l l i r D 800 f o r 700 e b m 600 u N 500
0 0 400 0 1 350 x P 300 H d e 250 l l a 200 t s n I 150
Number of Drill HP x 1000
400
100 1989
1990
1991
1992
1993
1994
1995
1996
Figure 11 Trend of deployment of drills in surface coal mines.
100
s e n i l g a r D f o r e b m u N
120
Number of Dragline
90
112.565
110
HP x 1000
104.15
103.298
80
93.085
91.013
70
0 0 100 0 1 x 90 P H 80 d e l l a 70 t s n 60 I
102.718
60
59 70.784
50
47 60.669
40
41
44
43
41
42
36
30
50 1989
1990
1991
1992
1993
1994
1995
1996
Figure 12 Trend of deployment of dragline in surface coal mines. 1189
1180
405
401.93 396.887
r e 1130 z o D f 1080 o r e b 1030 m u N 980
395
392.867 1123
1117
382.058
1071 352.302 1020
355.221 1018
Num ber of Dozer
9 83
0 385 0 0 1 375 x P 365 H d 3 5 3 . 7 4355 1 e l l a 345 t s 98 9 335 n I
HP x 1000 930
325
318.139
1989
1990
315 1991
1992
1993
1994
1995
1996
Figure 13 Trend of deployment of dozers in surface coalmines.
4400
4437
2231.879
2115.855
4291
4385
4223
4200 s r e p m4000 u D f o 3800 r e b m3600 u N
2200 2114.45
2063.683
4038
1902.232 1830.898 1755.192
3846
3663
3400
1486.111
Number of Dumper
3406
HP x 1000
2000 0 0 0 1 x 1800 P H d e l 1600 l a t s n I 1400
3200
1200 1989
1990
1991
1992
1993
1994
1995
1996
Figure 14 Trend of deployment of dumpers in surface coalmines. Table 7 shows the population of HEMM in Indian Surface coal mining.
Table 7 Population of HEMM in Indian surface coal mining. Year Shovels Dumpers Draglines
Drills
Dozers Scrapers Graders Payloader s
Crane
1989
717
3406
36
635
983
106
140
227
187
1990
787
3663
41
703
1020
100
142
243
227
1991
864
3846
41
703
1018
54
161
208
236
1992
892
4223
47
829
1189
65
169
271
269
1993
910
4385
44
802
1117
16
167
179
283
1994
946
4437
43
822
1123
19
186
195
288
1995
956
4291
42
871
1071
18
189
179
317
1996
961
4038
59
864
989
15
172
171
266
In the non-coal sector, surface mining operations involve in producing bauxite, copper, gelena and sphalarite, Granite, Iron Ore, Limestone, Mica and stone. There are number of state government undertakings and private companies working in these areas. Table 8 shows the trend in HEMM used in the non-coal mines.
Table 8 Trend in HEMM used in the non-coal mines. Year
Number of Mines
Electric Shovel
Diesel Shovel
Dumper
Dozer
Loader
Tractor
1980
188
76
331
1160
296
139
119
1981
184
71
333
1259
288
139
124
1982
202
80
328
1291
316
146
119
1983
209
86
326
1309
306
148
117
1984
220
96
349
1355
314
157
104
1985
236
168
329
1434
334
163
118
1986
274
161
358
1590
355
189
138
1987
293
165
418
1784
391
240
141
1988
255
164
364
1748
336
234
116
1989
286
88
455
2391
374
214
108
1990
300
80
474
2263
359
205
108
1991
368
92
553
2744
433
279
134
1992
397
99
566
3067
425
393
144
1993
438
92
697
3221
432
384
145
1994
479
103
720
3416
428
424
166
1995
448
97
753
2814
425
399
146
1996
457
68
841
3409
448
446
150
Manufacture of Surface Mining Machinery in India In collaboration with foreign companies Heavy Engineering Corporation (HEC), Bharat Earth Movers Limited (BEML), Hinduastan Motor (HM), TELCO manufacture number of surface mining machinery in India. Table 9 shows a list of some machinery manufactured in India.
Surface Mining Machinery Manufactured in India.
