Mining and the Environment

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A world’s leading producer

The Australian minerals sector is in the top five producers of most of the world’s key minerals commodities. Mine production has been increasing steadily during the last decades and went up by 20% from 2002 to 2007.

Australia is the world’s leading producer of bauxite and alumina, ilmenite, rutile and zircon, synthetic rutile and tantalum. It is the second largest producer of gold, iron ore, lead, uranium, diamonds (by weight) and zinc; the third largest producer of silver and nickel; the fourth largest producer of black coal and manganese; and the fifth largest producer of aluminium, copper and lignite.

An overview of advanced minerals and energy projects (April 2007). Source: Minerals industry factsheet

Mining is a key contributor to Australian economy

In the 1900’s, mining contributed to 10% of the Gross Domestic Product (GDP) and was dominated by gold production with smaller contributions from copper, lead and coal. It declined at the end of the gold rush and began to increase again in the late-1960s.

Between 1961 and 1971, production of iron ore increased from 5 to 57 million tons while production of coal increased from 41 to 73 million tons.

Production of iron ore and coal continued to grow through the 1980s, principally driven by export demand. Today mining contributes about 5.6% of Australia's GDP.

Australia is the world's largest exporter of coal, aluminia, iron ore, lead, zinc and the second largest of uranium. About two thirds of exportations head towards Asian countries. In 2007, mineral resource exports contributed around 60% of Australia's total commodity trade. From 2002 to 2007, minerals industry exports have totalled over A$300 billion.

Most major Australian commodities can sustain current rates of mine production for many decades.

Australian mineral exploration is still growing: spending in 2007 rose by 41% to A$2061 million. This increase reflected strong growth in prices for many commodities on the back of anticipated strong and growing demand, particularly from China.

Source: Australian Mineral statistics, June quarter 2008, ABARE 2008

The environmental cost

All mining extraction obviously involves altering the natural environment in some way. Several aspects of mining affect the immediate environment while others have a more global effect such as contributing to greenhouse gases emissions.

Soil pollution and biodiversity

Firstly, the waste materials which are produced from the mine may flow into waterways or leach into soil, heavily polluting the ecosystem. Many tailings deposits are not built as engineered structures, but simply through piling up of tailings slurries. Depending on the nature of the mining operation and extractive processes, these tailings may contain acidic or caustic material, heavy metals or cyanide, generally rendering the land unsuitable for any other future land use. Mine pits may become contaminated due to acidic water, potentially carrying high levels of dissolved heavy metals, infiltrating the pit. They are likely to remain contaminated in the absence of extensive rehabilitation measures.

Secondly, mining activities can be a threat to biodiversity. The removal of both flora and fauna from the mine site leads to gaps in the food chain for those fauna remaining, as well as problems with succession of plants after the mining has ceased.

Landscape impact of mining at the Argyle Diamond Mine, Kimberley, Australia - Source

Environmental Impacts Statements and rehabilitation measures

To minimise the damage mining companies are now required to conduct Environmental Impact Statements (EIS) and look towards rehabilitation of the site.

An EIS is a report aimed at decision makers outlining the predicted environmental effects of a planned action or project. Any action which endangers the existence or would impede the recovery of a native species is considered to be undesirable.

Rehabilitation of a mined site is generally a multi-step process. First, extensive research has to be conducted prior to mining. Seeds need to be collected for replanting at a later stage. After the mining phase, the regrowing vegetation is removed and landscape is mechanically reshaped to contours similar to those before mining. Topsoil is often respread, treated with fertilisers and planted with a cover crop of graminaceous plants and endemic legumes. Once the topsoil is deemed stable, dominant native trees and shrubs can be planted at densities related to pre-mining densities. 
If rehabilitation is successful, there will be little visual evidence that mining ever took place. However, a long natural development will always be required to ensure that abundance and richness of plant species fully resemble the unmined areas.

Greenhouse gas emissions per capita for selected industrialised countries,
measured in millions of tonnes of carbon dioxide equivalent. 
Data source: Turton (2004) - Source: State of the environment

Source : National Inventory by Economical Sector 2006

Mining contribution to greenhouse gas emissions

Australia contributes around 1.5% of global greenhouse gas emissions, but it is the greatest emitter in the industrial world on a per capita basis.

Although mines account for less than 0.02% of total area, the mining sector contributes around 8.40% to the total greenhouse emissions in Australia.

This figure is worse in the state of Western Australia where mining is a major economy contributor. In 2002, the mining and resources sector contributed around 17.5% to the total greenhouse emissions of the state. This is due to a number of new mines, mine expansions and the opening up of new offshore gas fields in the North West. 
Most of the state's emissions (74% in 2004) came from the energy sector - which includes a large number of energy-intensive industries linked to the mining and resources sector, such as oil and gas, minerals, bauxite refining, and iron and steel production. Emissions from the energy sector increased by 58% between 1990 and 2005.

As a result of the anticipated continued growth in the sector, the total contribution of the Australian mining and resources sectors to greenhouse gas emissions is likely to rise in the next few years despite government policy to reduce greenhouse emissions.

Sources
Australia's Identified Mineral Resources 2008 (AIMR 2008)
Year Book Australia, 2005 - 100 years of change in Australian industry
Minerals industry factsheet , Australian Bureau of Agricultural and Resources Economics, 2007
National Land Use Summary Statistics 2001/2002
National inventory by economic sector (2006)
Australian mineral statistics (quarterly) June 08
State of the environment, Western Australia, report 2007
HSC CSU Earth and Environmental Science

Links
Sunrise Dam Goldmine (NASA Earth Observatory) “Super Pit” Mine, Kalgoorlie, Western Australia (NASA Earth Observatory)