Non-coal mining : Environment Issues
Minerals constitute the back-bone of economic growth of India as it has been
generously endowed with minerals. Mining and quarrying sector accounts for 2.5% of
India’s GDP, as estimated by Central Statistical Organization.
According to Indian Bureau of Mines as on 31.3.2013, there were 3,693 reporting mines
(excluding atomic & minor minerals and petroleum (crude) & natural gas) in India
located in 22 states that reported production during 2012-13. Among them, 575 mines
belonged to coal & lignite, 635 to metallic minerals and 2,483 to non-metallic minerals.
There were 774 mines in Public Sector and the rest 2,919 mines in private sector. The
reporting mines were concentrated mainly in eleven states, namely, Andhra Pradesh,
Chhattisgarh, Gujarat, Jharkhand, Karnataka, Madhya Pradesh, Maharashtra, Odisha,
Rajasthan, Tamil Nadu and West Bengal and these accounted for 94% of the total
reporting mines. Reporting mine is defined as “A mine reporting production or reporting
‘nil’ production during a year but engaged in developmental work, such as, overburden
removal, underground driving, winzing, sinking work, exploration by pitting, trenching or
drilling as evident from the MCDR returns”. States rich in minerals where maximum
number of mining leases were granted are Rajasthan (25%) followed by Andhra
Pradesh (18%), Gujarat & Madhya Pradesh (10% each), Tamil Nadu (8%), Karnataka
(7%), Orissa (5%) and Chhattisgarh, Goa & Jharkhand (3% each). These ten States
together account for about 92% of the total leases executed
Environmental Aspects
The environmental impact of mining includes erosion, formation of sinkholes, loss of
biodiversity, and contamination of soil, groundwater, surface water by chemicals from
mining processes. Erosion of exposed hillsides, mine dumps, tailings dams and
resultant siltation of drainages, creeks and rivers can significantly impact the
surrounding areas, In areas of wilderness mining may cause destruction and
disturbance of ecosystems and habitats, and in areas of farming it may disturb or
destroy productive grazing and croplands. In urbanised environments mining may
produce noise pollution, dust pollution and visual pollution.
Mining operations may be categorized as either surface or underground.
Surface mining may be broadly defined to encompass open pit, open cast,
quarry, strip, dredging and placer (hydraulic) mining. Underground methods
include block caving and long wall mining. Most of these mining operations share
a number of common stages or activities, each of which has potentially adverse
impacts on the natural environment, social and cultural conditions, or the health
and safety of mine workers or communities in the environs of the mine. These
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activities are exploration, disposal of overburden and waste rock, ore processing and
plant site operations, tailings containment, treatment and disposal, infrastructure,
access and energy, and construction work camps and operational town sites.
Mining activities release suspended particulate matters (SPM) and gaseous pollutants
such as CO, NOx, SO2 etc. The air quality analysis is restricted to the determination of
particulate matters concentration i.e. PM10 and PM2.5. The ‘effluent discharge’ from the
workshop is a source of water pollution in these mines. The noise gets produced due to
operations of HEMMs and blasting activity. Thus, all three major pollutants namely air ,
water and noise are present in the mines.
Sources of Fugitive Dust Emissions
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•
•
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•
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Area Sources of Dust Generation / Monitoring Location
Mine face / benches: Drilling, Excavation & Loading
(Not required for benches operating below water tables however applicable for
operating benches above water table)
Haul Roads / Service Roads: Haul roads leading to Ore Processing Plant, Waste
dumps &
Loading areas and Service Roads.
Crushing Plant: Run-off-mine unloading at Hopper, Crushing Areas, Screens,
Transfer Points
Screening Plant: Screens, Transfer Points
Ore Storage & Loading: Intermediate Stock Bin / Pile areas, Ore stock bin / pile
areas,
Wagon / truck loading areas
Waste Dump Areas: Active waste / reject dumps
Air Pollution Management
Potential
Magnitude
Control measures
sources of of
air
air
pollution
pollution
Monitoring
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Drilling
Blasting
High dust
potential,
and risk of
occupational
hazard
High dust
potential,
impact last
for short
period.
Wet drilling technology
Driller shall be equipped
with closed cabin to reduce
occupational hazard. The
operator shall be provided
with masks, helmet, gloves
and earplug.
Environment and safety
department
will
do
surveillance
monitoring
and auditing.
Ambient
air
quality
monitoring
shall
be
undertaken at drilling site
to ensure that drilling
operation
should
not
affect the air quality. The
copy monitoring report
shall be marked to
regulatory agency on
quarterly basic.
By improvising blasting
technique
Water spray prior to
blasting
Mine manger will be
overall responsible and
organise training to
operators and workers
No blasting will be allowed
in the areas close to
human habitation – Rock
breakers will be employed
instead of blasting
Invoice order shall be
marked to statutory body
for EMP compliance.
(ii) Water pollution and waste water management
Water pollution is caused due to higher loads of suspended solids through orewashing at the screening plant, slimes generation in the stockpiles or dumps and
erosion over degraded lands. The main consideration is how to limit the extent of the
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flow of slimes into the natural streams in the area and prevent environmental damage.
The measures usually taken by the mines are the following:•
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•
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Construction of check dams to harvest rainwater and arrest surface runoffs;
Provision of garland drains around major waste dumps;
Provision of settling ponds at suitable locations and channelling flow of water
running down the hill or dumps to settling ponds.
Construction of tailings dams or ponds for left over residue from beneficiation
plants.
Waste Management
Overburden management of Indian mines is extremely poor; in most cases, the
waste is just piled up in huge heaps, and mining companies do not bother themselves
with measures to prevent run-off or fugitive dust from waste piles. The best use for
overburden waste is to backfill the excavated land, but it is rarely done in practice as
companies keep opening different faces of the mines without completely exhausting any
one of them. The result is that Indian mines are characterized by large numbers of pits
surrounded by big dumps all around. Fines from these dumps are carried by rainwater
into nearby watercourses or lands and pollute both. During dry summers, these dumps
become a key source of air pollution for the surrounding areas.
Overburden management
The overburden management and stabilization is important from the environmental and
aesthetic point of view. The most common method of stabilization is by plantation. In
addition, there are other preventive measures to arrest erosion particularly at the initial
stage of overburden management:
•
Excavation from a new pit should begin only after an existing pit has been
exhausted. This would ensure that the overburden and inter-burden generated is
used for backfilling the exhausted pit, instead of being dumped elsewhere.
•
Till a pit is exhausted, the overburden should be properly compacted and stacked
in specified locations in low-lying non-mineralized zones within the lease area.
•
The height and slope of the overburden dumps should be maintained to prevent
accidents.
•
Drainage should be considered to handle heavy rainfall.
•
Sedimentation tanks should be constructed to treat run-offs.
Environment Standards for mining activities.
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Central Pollution Control Board has notified environment standards for iron ore mines,
and is in the process of recommending standards lime stone mines .There is need to
prepare Comprehensive industry document and develop environmental standard for
other mineral.
Pollution Prevention Technologies/Measures Adopted
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Common measures/initiatives for containing pollution adopted by Indian mines are as
below:
• For minimizing dust/air emissions: Water Sprinkler, Black Topping of Roads,
Tarpaulin Cover on ore trucks.
• For managing Over Burden: Following norms for overburden benches as
prescribed by the Director General of Mines Safety (DGMS).
• Technologies used for minimizing pollution: Surface Miners, Wet Drilling, Side
discharge loaders and Load haul dumpers and conveyors, Radar based
monitoring of slope stability of benches in open cast mines, etc.
• Water Pollution Control: STP, ETP, Oil & Grease Separators, etc.
Current Status of Compliance
Open-pit mining is the dominant technique in case of non-coal mining in India. Modern
mining methods and techniques like surface miners, wet drilling, overburden
management codes, etc. help a long way in enhancing extraction and minimizing
pollution. However, activities like on-road transportation of ore; unscientific washing
process, rainwater runoff, etc. demand particular attention so far as environmental
degradation from coal mining is concerned.
Non-Coal mines are located in various parts and many are in very far off locations. The
respective State Pollution Control Boards/Committees carryout regular monitoring of the
mines in their jurisdiction. Central Pollution Control Board also conducts monitoring and
detailed inspection in case of serious complaints, parliamentary investigations and
research studies. Recently, CPCB has taken up the initiative of compiling the overall
status of iron orel mines in India and requested all mining companies to provide certain
relevant information including compliance status. As per conditions of Environment
Clearance given by MoEF, mines has to submit six monthly compliance report which
includes monitoring data for ambient air quality, water quality, and noise to
MoEF/CPCB/SPCB on regular basis. As per the above information, majority of the
mines show compliance to the regulatory air and water pollution standards/limits.
Future Strategies/Proposals
Some important future initiatives CPCB proposes to highlight are- Continuous Ambient Air monitoring at cluster of mining area
- Real time water quality monitoring of nearby water bodies
- Phasing out on-road transport of ore by rail and belt-conveyor based transport
systems.
- Adoption of better house-keeping practices.
- Substantial expansion of plantation and green-belt development.
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Compulsory adoption of automatic surface miners, wet drilling, abundant mine
filling practices.
Compulsory medical check-up and health status reporting for all mine workers.
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