Saturday, November 28, 2015

Social, Economic, and Environmental Impacts Of Bauxite Mining

Considering the scale of mining activities, it is not surprising that they have a wide range of social, economic, and environmental impacts. A selection of potential effects associated with the open pit mining of bauxite is shown in Figure 1. Impacts of open pit mining have been widely discussed in literature. For further information see (Eggert, 1994), (Sengupta, 1993), (UNEP, 1997), and (Martens, 1998). We distinguish betweenfour mining life cycle stages with respect to the originand nature of effects: exploration, mine development, mining, and mine closure.

Social, economic, and environmental aspects affected by bauxite mining
Figure 1. Selection of potential social, economic, and environmental aspects affected by bauxite mining.

Before a bauxite deposit can be mined, it has to be identified and its economic and technical viability demonstrated. The exploration phase causes almost negligible environmental damage due to drilling, grab and bulk sampling and pilot plant operation. Once a workable bauxite deposit has been identified, mining and processing facilities as well as essential supply systems and an infrastructure have to be set up. The mine development phase is characterised by construction activities which usually cause a significant change in the landscape, ranging froma mere visual impact through to severe deforestation and the destruction of natural habitats. The environmental impacts of mine development are more relevant than those arising from the previouslife cycle stage but much less than those related to bauxite extraction.

Strictly speaking, activities related to bauxite mining following mine development can affect all three environmental medialand, water and air. In general, “open pit operations produce far more waste per tonne of ore than underground operations, where there is no overburden and where someof the removed material canbe used to backfill excavationsas work progresses” (UNEP 1997).

This does not necessarily hold true for open pit bauxite mining due to the shallowness of ore layers, resulting in less overburden and enabling successive excavation and reclamation sequences. Since neither acid rock drainage orpotentially hazardous tailings nor waste material occur, the severest environmental problems related to bauxite mining usually arise fromland degradation. Excavation, extraction and waste disposal canlead to substantial soil degradation, deforestation and destruction of wild life habitats. Fortunately, most ground water levels are below the basic level of superficial bauxite deposits. Consequently, a lowering of the water table is not a major impact question for open pit operations. Water effluents from mine operation include drainage, wastewater from bauxite washing and surface run-off, carrying suspended solids. Significant dust emissions a rise from road transport, ore processing, and wind erosion from uncovered top soils unless appropriate measures are implemented. Gaseous air emissions are mainly caused by fuel combustion.

Due to the non renewable nature of mineral deposits, mines have a finite life span. The mine closure and decommissioning stage directly follows the cessation of mining. The objective of the rehabilitation and reclamation phase consists in creating a productive and sustainable post-mining land use for the site. Simultaneously, a number of goals related to the protection of public health and safety and to the minimisation of the environmental impact associated with seepage and drainage must be pursued. Pits and waste piles have their slopes stabilised and may be revegetated. In addition, plant growth and water quality have to be monitored. The future land use potential is usually dependent upon topography, drainage, vegetative species mixes and surface texture. Further more, the success of the reclamation efforts depends on precipitation patterns and physical and chemical properties of surface and near surface layers.

Apart from environmental impacts, mining activities also have economic and social effects. After successful exploration, changes in land use and land ownership may restrict former access to natural resources for local communities. In this context, a participation of all interested partiesis desirable during the processof social and environmental compliance prior to mining. During mine development, the construction of facilities, roads, settlements, and energy and fresh water supply systems may lead to a noticeable regional development in terms of improved living conditions, including the establishment of medical care and education centres.

In some cases, a relocation of indigenous communities will be inevitable. Further economic and social consequences of mining arise from direct employment opportunities and the following stimulation of local business development due to the increased purchasing power of the local population. The distribution of the economic benefits of mining changes the income distribution and social structure of the surrounding settlements. Education and training as well as improved living conditions may contribute to a profound alteration of cultural values and former life styles. Further more, indigenous people are very sensitive to any disturbance of their local environment. The migration of workers and others taking advantage employment opportunities directly or indirectly related to mining may significantly affect the former local communities.

When mining ceases, a serious economic decline in the area is inevitable unless alternative employment opportunities are available for the redundant mine workers and the related support services. Otherwise,the site and its surroundings dispose of facilities, buildings and infrastructure that may be useful to other industries or business forms. Alternative investment and re-employment programmes stimulated by the mining companies and government can help create new employment opportunities and thus alleviate  the adverse socio-economic impacts of mine closure. In the following, selected social, economic and environmental impacts will be presented and discussed from a global point of view.

Written by:
P.N. Martens, M. Rohrlich, M. Ruhrberg, M. Mistry (Institute of Mining Engineering I University of Technology Aachen, Germany).

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