Environmental impacts of iron ore mining

The exploration, exploitation and associated activities of iron ore mining directly infringe upon the environment and affect air, water, land, flora & fauna. These important natural resources need to be conserved and extracted optimally to ensure a sustainable development.

Iron ore mining and processing of ore, affects the environment in myriad ways causing:

  • Land disturbance and change in land use pattern
  • Affecting floral and faunal habitat
  • Disturbing the natural watershed and drainage pattern of the area
  • Disturbing the aquifer causing lowering of the water table
  • Air pollution due to dust and noxious fumes
  • Water pollution due to surface run off from different areas of mines, spoil dumps, seepages/overflow from tailings dam leads to siltation of surface water bodies and blanketing the agricultural fields.
  • Noise and ground vibrations due to blasting.
  • Socio-economic impacts

environmental Impact of iron ore mining on Land

Mining is a temporary land use of the area. Being a site specific industry there is no choice in siting a mining project, a luxury available to most other industries. Land is required not only for the mine excavation proper and laying approach / haul roads, but also for beneficiation plant, ore handling & dispatch units, waste dumps, tailing ponds etc. Land is also required for ancillary facilities and statutory buildings (workshops, stores, offices, canteen, and crèche).

The major impact on the land use during the pre-mining phase is removal of vegetation and resettlement of displaced population. During mining and post-mining phases, drastic changes in landscape with landform take place. The major associated impacts are soil-erosion, loss of top soil, creation of waste dumps and voids, disposal of wastes, deforestation etc. These impacts of iron ore mining on land can be minimized by careful planning the surface layout of the mining areas and by integrating the environmental aspects of each and every unit operation of mining activity. Another important aspect of the land management is the planning and design of the land reclamation programme right from the inception, including the development of the post mining land use planning for optimum utilisation of land in an efficient manner and for overall improvement in environmental scenario.

Impacts on Water Regime

Mining and associated activities have quantitative and qualitative impacts on the water regime in and around the mines. Therefore, it is necessary to plan the mining and associated activities in such a manner that their impacts on the water regime are as minimum as possible.

Air Pollution

The air quality in the mining areas mainly depends on the nature & concentration of emissions and meteorological conditions. The major air pollutants from mining include:

  • Particulate Matter (Dust) of various sizes
  • Gases, such as, Sulphur Dioxide, Oxides of Nitrogen, Carbon Monoxide etc. from vehicular exhaust.

Dusts are the single largest air pollutant observed in the iron ore mines. Diesel power stations, diesel operating drilling machines, blasting and movement of HEMM/vehicles produce NOx, SO2 and CO emissions, usually at low levels. Dust can be a significant nuisance to surrounding land users and potential health risk in some circumstances. Dust is being produced from a number of sources and through number of mechanisms such as land clearing, removal of top soil (during opening up of new areas), removal of OB/ore, drilling, blasting, crushing & screening, processing of ore, loading & unloading of material on site & subsequent transport off the site etc. In addition to this, wind action affecting stockpiles, dry tailings, exposed mining areas and waste dumps also generate significant amount of dust. Dust emissions from these operations manly depend on moisture content of the ore and type of control measures adopted.

Environment protection

As mechanised open cast iron ore mines becoming larger, deeper and more capital intensive, continuing efforts should be  made to improve upon the open cast mining activities through advances in the equipment size / design and practices and also through introduction of innovative techniques. The application of high capacity continuous surface mining techniques to harder formations, new concept of high angle belt conveying system, in-pit crushing systems (mobile and semi-mobiles), high capacity dumpers, automatic truck dispatch system, non-electric blast initiation systems etc. and developments in the area of bulk explosive systems hold out almost unlimited opportunities for upgrading the performance of opencast iron ore mining in India, while minimising the environmental impacts. In addition, the following proved cleaner technologies are need to be implemented in Indian iron ore mines, considering the suitability to the particular site:

  • Adoption of Wet drilling
  • Use of ripper dozer as an alternative to drilling and blasting
  • Use of hydraulic hammer/rock breaker as an alternative to the secondary boulder blasting
  • Use of opti blast technology and split charge blasting techniques wit air decking by the gas bags
  • Use of non electric(NONEL) initiation devices (EXEL of ICI and RAYDET of IDL)
  • Application of in-pit crushing and conveyor transport system as an alternative to all dumper transport system in deep mines
  • Dry Fog dust control system at the crushing, screening & material handling/processing plant as an alternative to de-dusting system with bag-house
  • Use of Hydro-cyclones and Slow Speed Classifiers in the wet

Iron ore mining

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