Mining in India - The History and the Present Scenario

7/27/2019 Mining in India - The History and the Present Scenario

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MINING IN INDIA THE HISTORY AND THE PRESENT SCENARIO

Contributed by

Prof. Phalguni Sen

Dept. of Mining Engineering

INTRODUCTION

The history of mineral development is as old as the civilization. In case of India,the mineral production dates back to the ancient times as the mining activitiescan be traced as far back as 6,000 years or so. The importance of mineraldevelopment for the economic growth of a country was realized in India longback. As early as 400 B.C. Chanakya in his Kautilyas Arthasastra mentionedMines are the sources of treasury, from treasury comes the power of

Government and the Earth whose armament is by means of treasury and army.

The remains of some of the old mine workings are a witness to this fact. A few ofthese workings have led to the discovery of a number of significant mineraldeposits, which are being worked in the present time. These include the lead-zinc deposit at Zawar, copper deposit at Khetri, and gold deposits in Karnataka.

HISTORY OF COAL MINING IN INDIA

India has a long history of commercial coal mining covering nearly 220 yearsstarting from 1774 by M/s Sumner and Heatly of East India Company in the

Raniganj Coalfield along the Western bank of river Damodar. However, for abouta century the growth of Indian coal mining remained sluggish for want of demandbut the introduction of steam locomotives in 1853 gave a fillip to it. Within a shortspan, production rose to an annual average of 1 million tonne (mt) and Indiacould produce 6.12 mts. per year by 1900 and 18 mts per year by 1920. Theproduction got a sudden boost from the First World War but went through aslump in the early thirties. The production reached a level of 29 mts. by 1942 and30 mts. by 1946 (www.coal.nic.in/abtcoal.htm).

HISTORY OF GOLD MINING IN INDIA

India has long been the site of gold mining, first from placers and then in moremodern times from the oxidized and primary zones of a variety of auriferousdeposits. Pliny, writing at the beginning of our era in his Historia naturalis,mentions the gold of India, and the land of Ophir mentioned in I Kings 10:11 inthe Old Testament can, according to some authorities, be equated with India. It iscertain that gold placers and the rich oxidized zones of auriferous deposits wereworked in India long before the Christian era, as evidenced by archaeologicaldata and written records. Large-scale mining in India began with the Mauryan


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colonization of the Deccan about the end of the fourth century B.C. Thediscovery of the Kolar field would seem to date from the beginning of theChristian era, probably coeval with that of the Hutti field to the north. The modernmining of the famous Champion Lode in the Kolar field, rediscovered in 1873,began about 1880 and has continued since that date (www.minelinks.com/

alluvial/gold1.html).

HISTORY OF DIAMOND MINING IN INDIA

Diamonds were discovered in India during the 4th century B.C., and India wasone of the first countries to mine the gem. India's diamonds were prized for theirsize and beauty for hundreds of years. "Indian" diamonds were mined innumerous locations that included Borneo (Landak), Golconda, Hindostan, andRaolconda. The majority of India and Borneo's diamond deposits were alluvial asopposed to kimberlite.

India's most prized diamonds are known as the "diamonds of Golconda," and the

most famous Golconda stones include the Hope Diamond, Koh-i-Noor Diamond,Orlov Diamond, and Sanc Diamond. The Darya-i-Nur (Sea of Light) was a rareblue-diamond weighed 186 carats, which was owned by the Nadir Shah of Persiaafter it was plundered from the last 'Great Mughal Emperor,' Aurangzeb's heirs inthe 'sack of Delhi' in 1739.(www.khulsey.com/jewelry/kh_jewelry_diamond_mines.html).

THE POST INDEPENDENCE ERA

After the political Independence came in the year 1947, the importance of role of

mines and mineral development in the countrys economic growth was realized,and an impetus to the development of the mineral sector was imparted in thecountry. Prior to independence, only a few minerals were mined and the countrywas largely depended on imports of commodities such as copper, lead, zinc,sulphur, graphite, petroleum, etc. On the eve of Independence, the annual valueof mineral production was merely Rs.0.58 billion, and the inventory details wereavailable only in respect of few minerals - coal, iron ore, chromite, bauxite,manganese ore and magnesite. The exploration of minerals was intensified andthe Geological Survey of India was strengthened for the purpose. The IndianBureau of Mines (IBM) was established to look after the scientific developmentand conservation of mineral resources. IBM was also assigned the responsibility

of conducting exploration with more of emphasis on coal, iron ore, limestone,dolomite, and manganese ore keeping in view the requirement of the proposedsteel plants. Later, in 1972 when the Mineral Exploration Corporation wasestablished, this function was transferred to it. Coal was the one to have receivedthe maximum attention for being the basic fuel for a whole range of industriessuch as steel, railways and power plants. Capacity for large-scale production ofvarious minerals was created in the public sector - National Coal DevelopmentCorporation (NCDC) 1956, National Mineral Development Corporation (NMDC)


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1958, Bharat Aluminium Company (BALCO) 1965, Pyrites, Phosphates andChemicals Ltd. (PPCL) 1960, Hindustan Zinc Ltd.(HZL) 1966, Neyveli LigniteCorporation Ltd. (NLC) 1957, Hindustan Copper Ltd.(HCL) 1967, Bharat GoldMines Ltd.(BGML) 1972, Steel Authority of India (SAIL), formerly Hindustan SteelLtd 1973.

Coal mining

With the advent of Independence, the country embarked upon the 5-yeardevelopment plans. At the beginning of the 1st Plan, annual production went upto33 mts. During the 1st Plan period itself, the need for increasing coal productionefficiently by systematic and scientific development of the coal industry wasbeing felt. Setting up of the National Coal Development Corporation (NCDC), aGovernment of India Undertaking in 1956 with the collieries owned by therailways as its nucleus was the first major step towards planned development ofIndian Coal Industry. Along with the Singareni Collieries Company Ltd. (SCCL)which was already in operation since 1945 and which became a Government

company under the control of Government of Andhra Pradesh in 1956, India thushad two Government coal companies in the fifties. SCCL is now a jointundertaking of Government of Andhra Pradesh and Government of India sharingits equity in 51:49 ratio.

Right from its genesis, the commercial coal mining in modern times in India hasbeen dictated by the needs of the domestic consumption. On account of thegrowing needs of the steel industry, a thrust had to be given on systematicexploitation of coking coal reserves in Jharia Coalfield. Adequate capitalinvestment to meet the burgeoning energy needs of the country was notforthcoming from the private coal mine owners. Unscientific mining practicesadopted by some of them and poor working conditions of labour in some of the

private coal mines became matters of concern for the Government. On accountof these reasons, the Central Government took a decision to nationalise theprivate coal mines. The nationalisation was done in two phases, the first with thecoking coal mines in 1971-72 and then with the non-coking coal mines in 1973.In October, 1971, the Coking Coal Mines (Emergency Provisions) Act, 1971provided for taking over in public interest of the management of coking coalmines and coke oven plants pending nationalisation. This was followed by theCoking Coal Mines (Nationalisation) Act, 1972 under which the coking coal minesand the coke oven plants other than those with the Tata Iron & Steel CompanyLimited and Indian Iron & Steel Company Limited, were nationalised on 1.5.1972and brought under the Bharat Coking Coal Limited (BCCL), a new Central

Government Undertaking. Another enactment, namely the Coal Mines (TakingOver of Management) Act, 1973, extended the right of the Government of Indiato take over the management of the coking and non-coking coal mines in sevenStates including the coking coal mines taken over in 1971. This was followed bythe nationalisation of all these mines on 1.5.1973 with the enactment of the CoalMines (Nationalisation) Act, 1973 which now is the piece of Central legislationdetermining the eligibility of coal mining in India (www.coal.nic.in/abtcoal.htm).


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THE PRESENT SCENARIO

Presently, India produces as many as 89 minerals comprising 4 fuel, 11 metallic,52 nonmetallic industrial and 22 minor minerals. Their aggregate production in1999-2000 was about 550 million tonnes, contributed by over 3,100 mines(reporting mines) producing coal, lignite, limestone, iron ore, bauxite, copper,lead, zinc, etc. More than 80 per cent of the countrys mineral production comesfrom surface mines and therefore, one must add the quantity of overburden tothat of the mineral production in order to assess the total amount of annualexcavation in Indias mining sector. The mining leases numbering 9,244 arespread over 21 States on about 13,000 mineral deposits occupying about 0.7million hectares which is 0.21 per cent of the total land mass of the country.

The total value of mineral production in 2000-2001was Rs. 568070 million, ofwhich the value of minerals other than petroleum and natural gas was Rs.

306751 million (http://mines.nic.in/imsene.html).

The resources of 64 non-fuel minerals as on April 2005 is given in Table-1.Table- 2 shows the coal reserve of the country as on January 2006,

Table- 1: All India Mineral Resources as on 1.4.2005

Sl..Mineral Unit _ Reserves

RemainingResources

TotalResourcesNo.

1 Andalusite Th.Tonnes 0 18450 18450

2 Antimony Tonnes Ore 0 10588 10588

Metal 0 174 174

3 Apatite Tonnes 6145575 20719133 26864708

4 Asbestos Tonnes 6040544 15695817 21736361

5 Ballclay Tonnes 32529793 46761403 79291196

6 Barytes Tonnes 34312780 39890567 74203347

7 Bauxite Th.Tonnes 899384 2390433 3289817

8 Bentonite Tonnes 25060508 505512899 530573407

9 Borax Tonnes 0 74204 74204

10 Calcite Tonnes 6742030 15831937 22573966

11 China clay Th.Tonnes 222121 2373540 2595661

Table contd.


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Table- 1: contd


RemainingResources

TotalResourcesNo.

12 Chromite Th.Tonnes 66128 146935 213063

13 Cobalt Mill. Tonnes 0 44.91 44.91

14 Copper Th.TonnesOre 369493 1024933.07 1394426

Metal 4383.97 7033.75 11417.72

15 Corundum Tonnes 604 83190 83795

16 Diaspore Tonnes 3125032 2212361 5337393

17 Diatomite Th.Tonnes 634 2251 2885

18 Diamond Carats 1205577 3376336 458191319 Dolomite Th.Tonnes 985156 6547952 7533108

20 Dunite Th.Tonnes 128074 39855 167929

21 Emarald NOT ESTIMATED

22 Feldspar Tonnes 38049836 52731827 90781663

23 Fireclay Th.Tonnes 561805 646393 1208198

24 Fluorite Tonnes 9213831 10951838 20165669

25 Fuller's Earth Tonnes 58200 256593879 25665207926 Garnet Tonnes 20975605 36680028 57655633

27 Gold Tonnes

Ore (Primary) 19253951 371035286 390289237

Metal (Primary) 85 406.12 491.12

Ore (Placer) 0 26121000 26121000

Metal (Placer) 0 5.86 5.86

28Granite (Dimen

stone)*000 cu.m. 1130024 36295977 37426001

29 Graphite* Tonnes 10749908 158025030 168774939

30 Gypsum Th.Tonnes 68658 1168218 1236876

31Iron

Ore(Heamatite)Th.Tonnes 7004168 7626220 14630388

Table contd.

Table- 1: contd


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RemainingResources

TotalResourcesNo.

32Iron

Ore(Magnetite)Th.Tonnes 58504 10560977 10619481

33 Kyanite Tonnes 1374191 101239032 102613223

34 Limestone* Th.Tonnes 12696674 162632240 175328914

35 Lead-Zinc Ore Th.Tonnes

Ore 125754 396826.27 522580

Lead Metal 2590.55 4616.7 7207.25

Zinc Metal 11092.89 13166.79 24259.68

Lead&Zinc Metal 0 118.45 118.45

36 Magnesite Th.Tonnes 76133 261749 33788237 Manganese Ore Th.Tonnes 138152 240418 378569

38 Marble Th.Tonnes 4700 1787938 1792638

39 Mica* Kilogram 48157843 325285576 373443419

40 Molybdenum TonnesOre 1500000 17786732 19286732

Containes MOS2 1050 11589.57 12639.57

41 Nickel Ore Mill. Tonnes 0 188.71 188.71

42 Ochre Tonnes 47867858 45573436 9344129443 Perlite Th.Tonnes 504 1385 1889

44 Potash Mill. Tonnes 0 21815 21815

45 Pt.Grp of Metal Tonnes Metal 0 14.2 14.2

46 Pyrite Th.Tonnes 56726 1617675 1674401

47 Pyrophyllite Tonnes 19489617 14205319 33694936

48 Quartzite Th.Tonnes 98544 1046413 1144957

49Quartz-Silica

Sand* Th.Tonnes 771508 2466703 3238211

50 Rock Phosphate Tonnes 52723492 252585084 305308576

Table contd.

Table- 1: contd

Sl.. Mineral Unit _ Reserves Remaining Total


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Resources ResourcesNo.

51 Rock Salt Th.Tonnes 13530 0 13530

52 Ruby Kilogram 1925.1 3346 5271

53 Sapphire Kilogram 0 450 450

54 Sillimanite Tonnes 11423994 62915875 74339869

55 Silver TonnesOre 115912738 128720729 244633467

Metal 6058 4154 10213

56 Sulphur Th.Tonnes 0 210 210

57Talc-Steatite-

SoapstTh.Tonnes 115526 196810 312335

58 Tin Tonnes 249497 86302812 86552310

59 Titanium Tonnes 25148538 363239828 388388366

60 Tungsten TonnesOre 0 87387464 87387464

Contained WO3 0 142094.35 142094.35

61 Vanadium Tonnes Ore 6318663 18529225 24847888

Metal 10769.78 54620.49 65390.27

62 Vermiculite Tonnes 1763630 674631 2438261

63 Wollastonite Tonnes 8533311 11709141 20242452

64 Zircon Tonnes 3705912 569748 4275660

* Provisional

Source: http://ibm.nic.in/reserves.html

Table- 2: Coal Reserves (in Billion tones) of India as on January 2006

TypeProved

ReserveIndicatedReserve

InferredReserve

TotalReserve

Coking 17 13 2 32

Non-coking 79 106 36 221

Total 96 119 38 253

Source: http://www.coalindia.nic.in/coalreserve.htmIn India, the Public Sector Companies contribute 100% of copper, diamond, lead,silver and zinc and lignite; 98% of coal, 60% of iron ore and 50% of manganese,


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bauxite, chromite and dolomite in the total mineral production. The value ofmineral production during 1999-2000 was estimated at Rs.452.3 billion of whichthe contribution from public sector was Rs.378.4 billion (84%). In the total valueof mineral production, fuel minerals accounted for Rs.372.3 billion (82%), metallicminerals at Rs.34.2 billion (8%) nonmetallic minerals Rs.18.3 billion (4%) and

minor minerals Rs.27.6 billion (6%). The mineral production in 1970-71, 1990-91and 1999-2000 are given in the following table (Table-3). It may be observedfrom the table that there has been a rapid growth in the production of coal andlignite, iron ore and limestone in the past three decades (TERI Report No.2001EE42).

Table-3: Production of some selected minerals in India (by mineral groups)

Mineral Unit 1970-71 1990-91 1999-2000 2005-06

Fuel minerals

Coal Million tonnes 73.7 211.3 300.0 407.22

Lignite Million tonnes 3.5 14.0 21.9 30.05

Crude oil Million tonnes NA 33.0 32.0 32.20Natural gas BCM NA 18.0 26.4 31.22

Metallic minerals

Bauxite Million tonnes 1.4 5.0 6.8 12.33Chromite Million tonnes 0.3 0.9 1.7 3.42

Copper ore Million tonnes 0.5 5.3 3.1 2.64Iron ore Million tonnes 31.4 55.5 73.5 154.43

Manganeseore

Million tonnes 1.7 1.5 1.6 2.00

Lead & zincore

Million tonnes NA NA 2.7 4.79

Gold ore Million tonnes NA NA 0.7 0.51Non metallic minerals

Limestone Million tonnes 23.8 70.1 127.9 170.38Dolomite Million tonnes 1.1 2.6 2.9 4.43Gypsum Million tonnes NA 1.7 3.3 3.14Diamond (000 Carats) 20 18 41 44.17

In 1970s, in India, a purposeful thrust was given towards surface mining to meetthe increasing mineral demand, and since then the countrys mining industry hasexperienced a phenomenal shift from underground to surface mining forproduction of different minerals in general and coal in particular. The upsurge of

the surface mining activities has resulted in establishing large size surface coalmines (Jayant, Nigahi, Dudhichua, Amlohri, Gevra and Dipka, Rajmahal,Piparwar, Ashoka, etc.) and surface metal mines (Kudremukh, Malanjkhand,Rampur-Agucha, etc.), increase in production from existing surface mines,increase in size of conventional mine equipment and introduction of newequipment and new technology.

Of the 89 different minerals that are mined today in India, most are coming fromsurface mines. Some of the minerals, produced exclusively or mainly from


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underground mines earlier, are currently being produced by surface mines also.Presently, in the country, the surface mines contribute the major share (morethan 80%) of the coal & lignite production, more than 50% of copper ore and lead& zinc ore and a considerable amount of manganese ore produced. Chromitecomes from both surface and underground mines. A small portion (about 10% of

the total production) of gold ore is also extracted by surface mining. Very recentlya surface mine has been opened up, and few more are likely to come intoexistence in near future, to extract uranium ore in the country. Only petroleumand natural gas come exclusively from underground mines.

Almost 100% of the countrys production of the minerals other than coal & lignite,copper ore, lead and zinc ore, uranium ore, chromite, gold ore and petroleumand natural gas comes from surface mines. More than 80% of the total mineralproduction, in terms of both volume and value, of India comes from surfacemines, and the same trend is likely to continue for the next few decades.

SURFACE MINING - THE CHALLENGES AND DEVELOPMENTS

The Challanges

The main challenge to the present-day surface mining industry is that ofextracting mineral from increased depth while fulfilling the increasing productiondemand and maintaining the economy of operation.

The average depth of currently operating surface coal mines in the country hasbeen estimated at 80m (Chaudhuri, 2000). The currently operating deepestsurface coal mine is Amlohri where the deep most working bench in Turra Seamhas reached a depth of 160m. The Amlohri mine has been planned to be worked

by surface mine upto a depth of about 300m. A number of other surface coalmines Jayant, Dudhichua, Nigahi and Jhingurda in NCL, Gevra in SECL,Sonepur-Bazari in ECL and Gautam Khani in SCCL- have been planned uptodepths exceeding 200m. Malanjkhand and Rampur-Agncha have been plannedto go to depths beyond 200m. Elsewhere in the world, a number of surface mines(Rossing uranium ore mine in Namibia, iron ore mines is Ural, borax mine of RioTinto in California and gold mine in Finniston, Western Australia) are operating ator planned to go beyond the depth of 350m. The Ekibastas surface coal mine inRussia has been planned upto a depth of 500m. The worlds deepest surfacemine, the Bringham Canyon copper mine in Utah, USA, is reaching a depth of760m (Banerjee, 2006).

In general the deep mines are of larger size, and with the increase in mine sizethe following problems are generally enhanced.

The problem of land acquisition and land clearance if forest areas are

involved.

The problem of resettlement and rehabilitation.


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The problem of increased stripping ratio.

The problem of increased generation of overburden/waste material and

subsequent overburden/waste dump planning -

With the increase in depth of working and increasing stripping ratio, the

quantity of overburden/waste material that is to be handled to produce acertain quantity of mineral/ore increases at a faster rate. Proper placementof the overburden/waste material in dumps, external and/or internal (incase of flat or gauntly dipping bedded deposits), calls for integratedplanning and design of overburden/waste dumps. The dump planningincludes the selection of dump site and dump geometry giving dueconsideration to the foundation competence and inclination, materialproperties (cohesion and effective friction), the likely environmentalimpacts, the hazard potential and the overall economics of dumpformation and maintenance.

The problem of slope stability

Stability of highwall benches and of overburden/waste dumps is of majorconcern in case of deep surface mines. As the depth of mine workingsincreases, the height of highwalls (and that of internal backfills incase ofbedded deposits) increases. To have stable slopes in mines, a properslope stability planning, slope formation and slope stabilization method isof prime importance. The deep surface mines are likely to have largeexternal dumps of greater height, which are more likely to developinstability. To have safe dumps, therefore, proper planning and design,suitable formation (including zonation) and slope stabilization methods(including installation of proper drainage system) are to be followed. Moreover to assess the stability (or instability) condition of slopes, same from ofcontinuous slope monitoring method/system needs to be implemented.

The problem of increased transport cost

As the mines are going to be deeper, the vertical lift from the bottom mostbenches and the average distance of ore and/or waste transport will beincreasing. At comparatively lower depth high capacity dumpers may beused in case of shovel-dumper operation to minimize the overall transportcosts. However, in case of high depth, the cost of dumper transport maybecome prohibitive, and in such cases the use of in-pit crusher conveyor(shiftable and/or high angle) system may have to be adopted.

The problem of blast vibration and air vibration

The problem of increased level of impacts on physical

environment (land, water, air, flora and fauna)

The problem of changes in hydrologic regime.

The problem of accumulation of noxious gasses in the

bottom benches


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In deep mines, the carbon monoxide and carbon dioxide gases producedby the diesel-operated equipment are likely to be accumulated in thebottom benches. In case of deep surface coal mines, there is also likelyhood of accumulation of methane in the bottom benches. If such acondition arises, suitable artificial ventilation measures have to be

adopted. The problem of creation of a large water body at the end of

mining.

The Developments

In the last few decades, a number of developments have taken place in thesurface mining industry of the country. The developments are in terms ofimprovement of conventional equipment, introduction of new equipment,introduction of new system and introduction of new technology.

Conventional equipment

In terms of development of conventional equipment, the power andcapacity have been greatly increased and improved/advanced featureshave been incorporated.

Presently, in India, the largest size electric rope shovel is being used inPiparwar Open Cast Project (OCP) of CCL. The 20m 3 shovel fitted with a25m3 bucket feeds the hopper of a fully mopile crusher. At amlohri OCP ofNCL and Rajmahal OCP of ECL, 20m3 shovel is working in conjunctionwith 170 t dumpers. The use of 10m3 shovel 120 t dumpers is becominga regular feature in the countrys surface mines. Hydraulic shovels ofbucket capacities 3 to 5m3 are used in many of the surface mines. The

draglines that are used in Indian Surface coal mines are mainly of 24m3

96m size. The drills used in dragline benches are of 300 325 mm diarange. In shovel benches drills upto 250 mm dia prevails. With theincrease in size/capacity of the conventional equipment, the modern onesalso incorporate improved features that optimize their operationalefficiency.

The modern day drills have features like auto-positioning, auto-levelling,auto-regulation of thrust and r.p.m., semi automatic handling of drill rodsand automatic recording of drilling data (that may be analysed latter)through the use of sensors and pre-programmed chips (Sen, 1987). Theshovel and draglines are fitted with system that automatically records the

equipment performance data. Some of the models of Volvo dumpers haveindependent elephant foot suspension system, which improves theperformance of these dumpers to a great extent particularly in roughconditions.

It is envisaged that the large size draglines of 45 to 55 m3 bucket size withover 100m dumping radius, 40 to 45 m3 capacity rope shovels, 10 to 15 m3

capacity hydraulic shovels, 850 h.p. dozers and 240 to 320 t dumpers willbe used in some of the large size coal mines in future (Banerjee, 2006).


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Elsewhere in the world, the large mines have increasingly switched over tohigher truck sizes of 290 t (Komatsu 930 E), 328 t (Hitachi EH 5000), 345 t(Caterpillar 797B) and 370t (Liebharr T282) (Banerjee, 2006).

New equipment

The latest equipment that has been introduced in Indian surface miningindustry is the surface miner. The first surface miner was introduced inone of the lime stone mine of Gujrat Ambuja Cement Ltd in Feb. 1995.Since then, the number of surface miners in Indian Surface mines issteadily increasing and the first surface miner in Indian surface coal minewas introduced in Lakhanpur OCP of MCL in June 1999 (Dey, Pathak andSen, 2000; Dey and Sen, 2001).

Presently, most of the surface miners being used in India are of WirtgenGmbh make. Only a very few are of Bitelli type, and very recently L & Tsurface miners have been commissioned in some of the OCPs of MCLand some lime stone mine in the country.

New System

In an effort to optimize the dumper performance, truck dispatching systemhas been introduced in few surface mines (Jayant OCP of NCL, WestBokaro mine of TISCO, etc.) of India. In this system, all dumpers serve allshovels in place of assigning a group of dumpers to a particular shovel.The available dumper is routed to the shovel that is either kept idle formaximum time or is going to be idle first for want of dumper. The systemmay be fully automatic or semi-automatic. This system offers theadvantages of minimizing the waiting time of dumpers thereby improvingtheir productivity and economizing the number of dumpers for a particular

number of shovels thereby lowering the required capital investment.In-pit crushing and conveying offers number of advantages overconventional dumper transport system (such as, high capacity, betterenergy utilization, lower unit transport cost, etc.). The system may beclassified into three main groups system with permanent in-pit crusher,system with relocatable in-pit crusher and system with fully mobilecrusher. In the system with permanent in-pit crusher, the material from allthe faces are transported to the crusher by dumper transport and thecrushed material are transported to destination by belt conveyor network.In case of relocatable crushers, one crusher serves a group of faces. Herealso, the dumpers are used to transport the material from the faces to the

particular crusher and the crushed material is transported to destinationvia belt network. This system offers the advantage of relocating thecrusher at an interval of time (usually 3 to 7 years) depending on themovement of the faces. In case of fully mobile crusher system, theexcavator in the face loads directly on the crusher hopper and thedumpers are totally eliminated from the transport system. The crushedmaterial is transported to destination via belt network.


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In India, a fully mobile in-pit crusher-conveyor system has been installed inPiparwar OCP of CCL for handling the coal from the lower most coal seam(Lowar Dakra) face. The coal is excavated and loaded by a 20m3 shovelfitted with 25m3 bucket to the fully mobile crusher hopper and the crushedcoal is directly transported to the pit head washery via a belt network. The

system handles a production of about 7.5 million tonnes per year(Srivastava, 1998).

Recent steep hike in diesel price may compel the surface mining industryto explore the applicability of non-diesel type of transport systems in themines, particularly in case of deeper mines. In-pit crushing-conveyingsystem is a proven technology and use of high angle conveyors (to takecare of the vertical lift) and trolley wire assisted truck haulage are otheralternatives to the conventional truck haulage system. Trolley wireassisted trucks are operating in many mines in USA, Canada, South

Africa, Zambia and Zimbabwe (Banerjee, 2000).

Extraction of developed coal seams by surface mining method is one of

the challenges to the present day coal mining industry in India. Severalproblems uncertain stripping ratio, dilution of coal quality, inefficientdrilling and blasting and falling of HEMM are generally associated with thismethod, and the method becomes less efficient.

In case, the coal is of low incubation period and/or fire exists in thedeveloped workings of the coal seam(s), the problems are furtheraggravated. To reduce some of these problems and improve the safety ofoperation, the system of integrated blasting of benches in coal seam(s),parting of contiguas seams and the last overburden bench has beenexperimented and adopted in some of Indian surface coal mines (WaniOCP of WCL, Gautam Khani OCP of SCCL) extracting developed coalseams.

New Technology

Blasting is the predominant method of rock breakage in hard rock mines.A lot of improvement has taken place in recent years in the type ofexplosives and the blasting accessories that are used in surface mines.Most of the present-day surface mines use site mixed emulsion explosiveswith the help of pump trucks with bulk loading facility. The uses of non-electric initiation systems are also becoming popular. The electronic delaydetonators have been developed recently and its first trial in an Indiansurface mine was carried out in 2004. These detonators permit high

accuracy in delay timing, large number of delays within the range of 0 to15000 milliseconds and use of centralized networked blasting (Banerjee,2006).

Surveying is an important operation in surface mines for slope monitoring,equipment positioning and preparation of mine plans including that ofdumps apart from day-to-day jobs of measurement of faces, highwall


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benches and dumps. With the increase in mine size and mine depth, itassumes a greater importance.

For the surveying operations, the Smart Stations are gradually becomingpopular and replacing Total Stations. The Smart Stations provide thefacilities of both the GPS and Total Station.

Monitoring of slopes (highwall and dump) is very important to assess theslope stability (or instability) condition in surface mines. The slopemonitoring is important from the points of view of maintaining a safeworking condition for both men and machine, to provide advance andaccurate information about any impending slope failure and to providesuch information that the failure mechanism may be understood and theappropriate remedial or mitigating measures may be adopted.

The various slope monitoring techniques that are available may beclassified into two main categories observational techniques andinstrumentation techniques. The observation techniques include terrestrialsurveying, EDM and automatic surveillance and surveying with GPS. Theinstrumentation techniques include use of movement indicators,convergence meters, strain meters, joint meters, extensometers,inclinometers, deflectometers, etc. (Mohan, Mishra and Sen, 2005).

However, the most effective slope monitoring system is through micro-seismic applications. In this system, network of geophones is used todetect the enhanced micro-seismic activities that may take place in theevent of the slope becomes stressed. This is a continuous monitoringsystem and can provide both the visible and audible alarm system.

SURFACE MINE

DefinitionA surface mine is a mine in which no part of its workings extends below thesuper adjacent ground.

Types

Surface mines may be classified into different types Open-pit mines, Area(modified open-pit) mines, Strip mines, Contour mines and Mountain top removal(full or partial) mines.

Open-pit and area mines are associated with extraction of thick deposits. Thesejustify mining of deeper overburden/cover rock. They are typically multiple benchtype operations with special consideration required for the vertical lift

requirements of the haulage system.

Strip mines are associated with extraction of flat (dip 1 in 20) bedded deposits

(seams) commonly under shallow cover. The seam/seams is/are extracted innumber of long strips of predetermined width after getting released by theremoval of the overburden/cover rock. The strips are generally laid along thestrike direction. Single or multiple seams may be extracted by this method. Directoverburden disposal techniques are utilized as much as possible.


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Contour and mountain top removalmining permit the extraction of deposits invery hilly or mountainous terrain. Benching and direct disposal techniques areused individually or in combination for overburden removal and replacement.Contour mining permits the extraction of bedded deposits, and mountain topremoval mining is generally used for extraction of massive or cap type deposits

(Martin et. al., 1982).

MERITS AND DEMERITS OF SURFACE MINING

Surface mining methods offer a number ofadvantages over underground miningmethods. Most important of them are

Higher production

Greater safety and better Workingenvironment

No support problem

No limitation on head room

Possibility of high degree ofmechanization

Higher recovery

Low grade ore can also beextracted profitably

Higher flexibility of operation

Greater concentration of alloperations and simplifiedmanagement of men and machines

Higher productivity (output)

No/very less ventilation problem

No roof problem

Lighting/illumination problem is less

Less limitation on the size andweight of equipment

Less cost of production

Better grade control

Less gestation period

Lower specific investment, (i.e.lower capital cost per tonne perannum production)

After-mining land-use potential maybe increased by proper reclamation

Surface mining methods also have some disadvantages in comparison tounderground mining methods. The most prominent ones are

Workings are exposed to open weather

Problems of maintaining slopes and roads during rainy season

Handling of large quantity of unproductive material (overburden/waste rock)

Problems of ground vibration and air vibration (noise) due to blasting

A large land area is affected

Adverse effects on ecology and environment land, water and air pollution

Emplacement of large quantity of overburden/waste material in spoil piles/wastedumps/overburden dumps

Maintenance of mechanical and environmental safety of the wastedumps/overburden dumps

Monitoring of waste dumps/overburden dumps and their stabilization in case ofoccurrence of any sort of instability

Capital intensive


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High reclamation/closing cost

Documents

Mining in India - The History and the Present Scenario