Open cast mines in Jharkhand continues to be a death trap.
What are open cast mines?
Open-pit mining, also known as opencast mining, is a surface mining technique that extracts minerals from an open pit in the ground.
It is the most common method used throughout the world for mineral mining and does not require extractive methods or tunnels.
Generally a traditional ‘cone-shaped’ excavation is done.
The technique is used when mineral or ore deposits are found relatively close to the surface of the earth.
Open-pits are sometimes called ‘quarries’ when they produce building materials and dimension stone.
Dhanbad has 105 mining leases altogether comprising underground, open cast and exhausted mining areas.
Some leases are not operational because of lack of statutory clearances.
How the mining is done?
Opencast mining operations involve the removal of huge quantities of overburden, dumping, and backfilling of the excavated area
Overburden removal refers to the removal of top-soil to expose the coal seams making them ready for mining.
Tailings are a by-product of mining. After ore is processed the resultant waste stream is termed “tailings”.
Backfill typically contains these tailings.
What are the advantages of Open cast mining?
Full visualization of exposed orebody and negligible ore loss
Greater concentration of operations, better grade control and blending,
No need of artificial light with natural ventilation round the clock.
Greater safety, minimum mining hazards like gasification, roof and wall support.
Easy pumping of sub surface water
No restriction of working with heavy and bulky machineries.
Lower capital and operating costs,
Minimum mine development work
Early production and quick return of capital invested.
What are the impacts of such mining?
Ecosystem Damage - The ecosystem that was present at the time prior to mining activity is basically destroyed.
Soil degradation – Various mining activities, particularly open pit, affect the topsoil and subsoil to a great extent by changing the natural soil characteristics. e.g. texture, grain size, moisture, pH, organic matter, nutrients etc.
Overburden differs substantially from previous local soils, and some maybe even toxic for plants.
Loss of agricultural and forestland - In case of open cast mining there will be complete loss of agricultural land and deforestation in and around the pit.
Water pollution - Water pumped into mines can affect local water table depths, resulting in the release of acidic mining water into surface waters.
The damage of natural drains and waste dumps may act as a barrier to the natural flow of rainwater
Water logging and Flash Flood - This will result in water logging and flash floods which will damage the agriculture and to local properties downstream.
The seasonal filling of nearby reservoirs and recharging of the groundwater around the area will be affected.
Landslides - Opencast mining on hill slopes, particularly in areas of heavy rainfall, is vulnerable to landslides causing loss of human life, property and deforestation.
This can be controlled by geo-technically designed slope of the mine and adequate support system.
Affects livelihood - The land owners, often tribal population, and contractual farmers living within the Mining Lease area are affected.
How to overcome these issues?
Loss of Agriculture - New agricultural land is developed and aforestation is done under overall land-use planning.
Soil degradation - Topsoil and subsoil must be removed separately and stockpiled at an easily accessible place.
These soils can selectively be re-laid to reclaim degraded land for agriculture
Water logging and Flash Flood - The changes in the drainage pattern can be anticipated from the expected post-mining surface contours.
Action plan for the surface drainage pattern can be designed accordingly.
Landslides - This can be controlled by geo-technically designed slope of the mine and adequate support system.
Rehabilitated people must be compensated by cash, separate housing, employment, health care, education, and other facilities.
