Extraction of metals has been practiced since antiquity. Over thousands of years this exercise has crystallised into the modern commercial mining that we see today. Mining is both a useful and necessary economic pursuit since it contributes enormously at the macro-economic level to the GDP, foreign exchange earnings, taxes and employment in rural areas. Undoubtedly, mining is a large-scale lucrative business and its benefits can be enjoyed by people from various socio-economic strata.
However, this industry functions under the looming shadow of environmental degradation. Mining faces challenges as a result of its social, economic and environmental footprint. Mining operations like drilling, blasting, extraction, transportation, crushing and other associated activities are carried out in underground and opencast mines. Pollution from mine waste rock and tailings need to be managed for decades, even after the suspension of the mine. The level of pollution depends on a variety of elements such as the local geology, the know-how and environmental commitment of the company. There is a need for balance between mining and environmental requirements.
The source of dust in mines can be classified into primary sources that manufacture dust and secondary sources that disperse the dust and carry it to other places as fugitive dust. Drilling, blasting, hauling, loading, transporting and crushing, all central to the mining industry generate dust. Air pollution in mines is mainly due to fugitive emissions of particulate matter and gases including methane, sulphur dioxide, oxides of nitrogen and carbon mono-oxide. Needless to say opencast mining is more liable to cause air pollution than underground mining.
In recent times respiratory diseases such as chronic bronchitis and asthma have seen an unprecedented rise due to high levels of suspended particulate matter thus causing health hazards to the exposed population. Ironically, the unrestrained dust not only creates severe health hazards, it also effects productivity of the mine by hampering visibility, causing ruination of equipment leading to increase in maintenance cost. The dust is also detrimental to agricultural practices since it pollutes nearby water bodies and stunts crop growth by shading and clogging the pores of the plant. Generation of dust also leads to loss of fines which are road surface binders.
Control Measures being put to use:
(a) Water spraying on haul roads by mobile and fixed sprinklers
(b) Dust extractors in Coal Handling Plants and drilling equipment
(c) Black topping of service roads
(d) Avenue plantation
(e) Dust masks
* Acid Mine Drainage
Distinctive types of waste bodies originate from the weathering and leaching of sulphide minerals. Acid Rock Drainage occurs when sulphuric acid is created because sulphides, present in rocks are exposed to air and water. Acid Mine Drainage is the same process occurring on a magnum scale.
When water reaches a certain level of toxicity, thiobacillus ferroxidans, a naturally occurring bacteria sets into action, accelerating the oxidation and acidification process. This acid doesn’t remain in-situ and is carried off the site by rainwater or surface drainage and finds its way into nearby streams, lakes and groundwater. The consequences that such an event has on all things biotic is palpable.
* Heavy Metal Contamination
As in the case of Acid Mine Drainage, when the likes of arsenic, cadmium, lead, cobalt, copper, zinc and silver found in excavated rock, come in contact with water, metals get leached out and carried downstream, thus causing heavy metal pollution.
* Processing Chemicals Pollution
When chemical agents (eg. Cyanide) used by mining companies to separate the target mineral from the ore, spill or leak from the mine site and into surrounding water bodies, they transform into a death knell of humans and wildlife.
* Erosion and Sedimentation
In the absence of mitigation tools and strategies, erosion of loosened, exposed earth may carry sizeable amounts of sediment into streams, rivers and lakes. This excessive sedimentation can clog riverbeds, causing them to change course which may result in flooding of some parts and desertification of others. Sedimentation can also suffocate watershed flora and fauna.
* Water Levels
Mining is largely responsible for depleting surface and groundwater resources. As the water table falls, damage to habitats dependent on these fresh-water sources is inevitable. For example, the amount of water pumped by mines in the northeastern Nevada desert amounts to more than 580 billion gallons of water between 1986-2001, which is estimated to be enough to keep New York taps happy for a year!
Control Measures being put to use:
(a) Industrial effluent treatment plants
(b) Silt arrestors/ Siltation ponds/ Sedimentation ponds
(c) Sewage Treatment Plants
Deforestation, Land pollution and Soil Fertility:
Cutting down of trees in order to increase access to buried mineral resources inevitably results in deforestation. This causes immense imbalance in the ecological structure that exists in the biosphere. The ecosystem that has thrived within these forested areas is compromised and biodiversity is irretrievably lost. Moreover, surface sediment is loosened thus adding to land degradation and the erosion of the fertile layer of topsoil.
Mining causes substantial visible damage to the land irrespective of techniques used. Large scale excavations, cutting of roads, removal of top soil, dumping of wastes and reduction to wasteland are just a handful of examples of what is inflicted upon land by mining. The whole industry is perpetually disinclined to overhaul and handle the waste for economic reasons.
Although underground mining has considerably less impact than opencast mining on land, it causes enough damage through subsidence as observed in Jharia and Raniganj Coalfields. The surface subsidence inflicts severe damages to engineering structures and public works such as highways, buildings, bridges and drainage besides interfering with ground water regime. It is calculated that, together with oil prospecting, mining is threatening 38% of the last stretches of the world’s primary forests.
Sinkhole subsidence is an abrupt depression at the surface that is hazardous to life and property due to its tendency to occur without warning. Sinkholes occur either due to natural factors or due to human tampering. Failure of mine roofs cause overburdened cavities to eventually cave in and make sinkholes appear at the surface. This phenomenon is unpredictable but can be mitigated. Customized designs of mining supports and construction of walls to form a barrier in areas prone to sinkholes can help in controlling sinkholing to a certain extent.
Indian Mineral Industry:
India has an enormous mining industry. India churns out 89 minerals including four fuel minerals, 59 non-metallic minerals, 11 metallic minerals and 22 minor minerals. Bihar and Madhya Pradesh produce more than a quarter of the mineral production of the entire country. Oil and gas make up for another quarter and are procured from offshore sites. Rajasthan, Madhya Pradesh, Orissa, Gujarat and Goa produce the bulk of the metallic and non-metallic minerals while coal resources are confined to Jharkhand, West Bengal, Orissa, Madhya Pradesh, Maharashtra and Andhra Pradesh. With its contribution of about 16 percent in exports and 20 percent in imports, the mineral sector is an important component of India’s foreign trade.
The Centre and the State are both responsible for the management of mineral resources of India. The basic laws governing this sector are The Mines and Minerals (Development and Regulation Act, 1957, (‘MMRD’) and the Mines Act, 1952. All mining activities have to conform to the environmental legislation of India. The relevant acts are Environment Protection Forest (Conservation) Act 1980 (amended in May 1992) and Environment Protection Act and Rules 1986. The Environmental Impact Assessment Notification, 1994 also apply for all the mining projects.
Reconciling the role of mining in the framework of sustainable development has been wrestled with for decades. Keeping in mind the accelerated increase in the need to secure a stable supply of minerals India has to augment its resource base considerably through options such as intensive exploration drive, improving the recovery and production from an existing resource base and warranting supplies through imports.
Technically robust approaches to managing and controlling the environmental impact of mining have been developed and must be further perfected and at the same time socio-economic issues that present unresolved challenges must also be tackled. It is indeed heartening to find that the National Environmental Engineering Research Institute has envisaged a set of policies to ensure primary environmental, social policies and guidelines that include:
- Policy and procedures for environmental assessment, whereby potential impacts are taken into account in selecting, siting, planning, and designing projects.
- Policy to encourage and support borrowing governments to prepare, implement and maintain environmental action plans.
- Policy to promote economically viable, environmentally sustainable and socially equitable water management.
- Policy to ensure that indigenous people benefit from development projects and those projects’ that have potentially adverse effects are avoided or mitigated.
- Policy and procedures towards displaced persons in operations involving involuntary resettlement.
- Policy on forest sector lending to reduce deforestation, enhance the environmental contribution of forests, promote aforestation, reduce poverty, and encourage economic development.
- Policy to support the protection, maintenance, and rehabilitation of natural habitats.
The static location of the mineralized zone of interest controls and limits all aspects of mining development including the method of mining, location of mine facilities, requirements for new infrastructure and services (or conflict with existing infrastructure), and the suitability of waste management or disposal methods. This in turn profoundly influences the environmental, social and health impacts of mining developments, as well as the economic viability of developing a given mineralized zone.
The challenges with environmental assessment of mining projects are two fold. Firstly, environmental, social and health costs should be given adequate consideration while determining the economic viability. Secondly, adequate mitigation measures should be incorporated into the project cycle, including project design, implementation and decommissioning plans.
As Rajah Banerjee of the Makaibari Tea Estate states on his website, “Freedom is the ultimate desire of all human beings. Sustainable impulses are the foundation towards this goal. The impulses released are dynamic in its synergy as it’s holistic. Holistic synergies address and redress economics, politics and the environment, so essential for a healthy planet.”
It is doubtful if a practice of extraction on non-renewable resources can ever be sustainable. They both stand for objectives that are at cross-purposes with each other. However, with the government’s approach to environmental regulation shifting from the ‘Ivory Tower’ policy of centralised decision making, detailed regulations and command and control approaches towards setting clear standards and guidelines there is hope that post operation environmental clean-up and economic accountability to the society and community will be handled with greater competence.