Environmental Impacts

Both surface and underground mining can have severe environmental impacts by disrupting the landscape, removing vegetation and topsoil, contaminating the air with dust and toxic substances, and causing toxic compounds in mining spoils to percolate into the groundwater.

Restoration and rehabilitation of sites is becoming more common, but it can also be expensive. The success of restoration depends on the characteristics of the site, the quantity of material removed, the depth of the deposit, the composition of the surrounding rocks, soil and ore, and the type of mineral being mined, as well as environmental regulations and how well they are enforced. The mining industry and conservationists disagree over whether rehabilitation can restore ecosystems to their original state and whether that is necessary in particular cases.

Minerals processing also has environmental impacts. Most deposits generally contain less than 30 per cent of the desired metal and often contain less than 1 per cent. This means large quantities of materials must be dug up and processed to get a much smaller quantity of minerals; inevitably, there are large amounts of waste materials left over. These 'tailings' can cause environmental problems if they are just dumped in piles (which is often the case) or poured back into the hole. The dust and water leaching through this waste can carry toxic materials into the environment if the tailings are not covered and stabilised.

As minerals are used up, miners have to resort to lower grades of ore; and the lower the grade of ore, the worse the environmental impact. An example is copper:

Four centuries ago, copper ores typically contained about 8 percent metal; the average grade is that at least eight times as much ore now must be processed to obtain the same amount of copper. An estimated 990 million tons of ore were mined to produce about 9 million tons of copper in 1990. (Young, 1992, p. 108)

Mining and mineral processing is one of the largest users of energy worldwide, and therefore contributes heavily to air pollution and global warming. One of the most energy-intensive mineral industries is steel-making. While the energy required for processing (per unit of metal mined) has declined in some cases due to technological improvements, the amount of energy used has increased because of lower grades of ore and poorer accessibility of deposits. For example, lower-grade deposits require more energy because greater quantities of material have to be mined and handled, and more energy is needed to process it since there is more of it and the ore has to be ground more finely.

The Commonwealth Government (1990) recognises that, although resource limits may not be met in the foreseeable future through the action of pricing mechanisms, ecological limits may be crossed: 'Biological systems may approach a state of collapse before the market reflects significant ecological stress' (p. 6). However, the government also argues that the exploitation of non-renewable resources should go ahead 'in the most efficient manner possible' (p. 9), taking full account of the need to maintain ecological systems and minimise environmental damage.

Environmentalists argue against the continuing use of non-renewable resources at exponentially increasing rates, which shortens the time span to depletion:

The environmental damage from nonstop growth in mineral production will eventually outweigh the benefits of increased materials supplies&emdash;if it does not already … An alternative goal would be to maximise conservation of mineral stocks already circulating in the global economy. (Young 1992, p. 116)

They argue that it would be better to reduce our use of minerals through using less, recycling and reusing more, and finding substitutes that are renewable, &emdash;for example, by replacing the use of coal and oil for energy with solar, wind and tide energy. Some go further, and argue that economic growth, because it depends on increasing use of minerals and other non-renewable resources, cannot be sustained.

Also, the increasing costs of extending the reserves will have an impact on the distribution of minerals, which in turn will have an impact on equity. It is the high-income nations that seem to be benefiting most from the readily accessible reserves. It is possible that only the expensive and energy-intensive reserves will be left for future generations and for low-income nations to mine in the future.

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