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• Mineral mining pollutes the environment
• Large-volume of waste
• Tailings
• Energy use
• Air pollution
• Water pollution
• Abandoned mines sites
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Mineral mining pollutes the environment

People have always used metals and minerals and products made from or with minerals in a nearly infinite number of ways. With the increase in population and real per capita income, the demand for mineral commodities is likely to rise in the future.

Yet, the extraction of metals is a violent process which may have a great impact on the environment. In some of the World's most famous regions, it is hard to argue that mineral production, processing and use generally benefits the local ecosystems concerned or make them more productive. Overall, the ability of local ecosystems to provide biological benefits has often been seriously impaired by mining and mineral processing. In the most modern mines, smelters, refineries, recycling centers and landfills, there may be a considerable reduction in the damage done to natural capital per unit of output than in the past. But growing demand for minerals also means that total output is higher and so in absolute terms the damage function may be increasing.
Source : IIED - Mining, minerals and sustainable development

The most important potential environmental impacts of mining results from :
Large-volume of waste
Tailings
Energy use
Air pollution
Water pollution
Abandoned mines sites

 Large-volume of waste

Large-scale mining operations inevitably produce a great deal of waste. But, contrary to the idées reçues, mining waste are not inert, they are not simply earth from topsoils and gangue from ores. They often contain toxic chemicals, such as cyanide, added to the ore in order to extract the metal. In addition to loss of productivity, these wastes can have a profound effect on the surrounding ecosystems. Where they are not physically stable, erosion or catastrophic failure may result in severe or long-term impacts. Where they are not chemically stable, they can serve as a more or less permanent source of pollutants to natural water systems.

These impacts can have lasting environmental and socio-economic consequences and be extremely difficult and costly to address through remedial measures

Tailings

Tailings are finely ground host rocks resulting from the chemical extraction of the wanted minerals. This residual slurry contains at least 50% water, but also large amount of chemical reagents and heavy metals.
Tailings are usually discharged into storage facilities and retained by dams or embankments; they can be very large engineering works.

Energy use

The International Institute for Environment and Development estimates that between 4 and 7% of energy demands in the world is used in mining but this varies significantly among countries.

Air pollution

Dust caused by digging, earth and ores manipulations is an important cause of air pollution.
Smelting (heating up ore to separate it from the gangue) produces very large amounts of air pollutants, notably as SO2 (sulphuric oxide, responsible for acid rain).
Between 4 and 7% of energy demands in the world is used in mining but this varies significantly among countries, estimates the IIED . Consequently, mines are also a source of greenhouse gas emissions.

Water pollution

Acid mine drainage is caused by many mining operation, in particular the extraction of nickel, copper, iron, zinc, cadmium, lead and coal ores. When chemically reactive minerals are extracted and exposed to the air, they spontaneously react with water and oxygen to produce sulphuric acid and metal ions, responsible for pollution by heavy metals. The combination of acids and metals can have severe effects on the ecology of local watercourses and the metals can enter living organisms and bio-accumulate up the food chain. This phenomenon can last long after the mine closed down. This acidic reaction can also occur with tailings.

Tailing dams are prone to seepage and can seriously contaminate water as a result. In the worse cases, they might collapse catastrophically as it occurred in 2000 in the Romanian gold mine of Baia Mare.

Highly toxic chemicals (sulphuric acid, cyanide, organic reagents) are used to separate minerals from their gangues and could contaminate water.

Solid particles from waste, ore or surface installations, when going into water, could affect aquatic flora and fauna and physically choke local waterways and lakes.

Further to water pollution, excavation can also influence the hydrology around the excavated area: nearby-streams or wells could become dry. Underground work could cut across aquifers.

Abandoned mines sites

The environmental issues of current and prospective mining operations are daunting. But some of the continuing effects of mining and smelting that occurred over past decades, centuries, or even millennia, are far more worrying. These sites have proved that mining has serious long-term impacts. Society is still paying the price for natural capital stocks that have been drawn down by past generations.

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