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Also in Heating oil explained Heating oil Where our heating oil comes from Use of heating oil Prices and outlook Factors affecting heating oil prices. Hydrocarbon Gas Liquids. Natural gas. Also in Hydrocarbon gas liquids explained Hydrocarbon gas liquids Where do hydrocarbon gas liquids come from? Miners face great physical risk due to accidents, explosions and mine collapses. In China, roughly 4,, workers die from underground mining accidents each year.
Miners are also directly exposed to toxic fumes, coal dust and toxic metals, increasing their risk for fatal lung diseases such as pneumoconiosis and silicosis. The toll on the physical landscape is severe. One of the most serious impacts of coal mining is acid mine drainage. Acid mine drainage contaminates ground and surface water with heavy metals and toxins exposed by mining. This destroys aquatic ecosystems and water supplies that communities depend on for drinking and agriculture.
During mining operations, enormous amounts of groundwater are drained from aquifers so mining companies can access coal seams — up to 10, litres per tonne of coal.
This extraction will drastically lower the water table, rendering local wells unusable and impacting nearby rivers. Open cut mines also result in massive erosion and sedimentation of streams, wetlands and rivers. Today communities around the world — in countries as diverse as China, India, the United States, Indonesia, Australia, Colombia and South Africa — are rising up to oppose new coal mines and demand reparations and restoration for the impacts to their livelihoods and the natural environment.
Mechanical and chemical processes are used to grind up rock into a fine sand to extract the valuable mineral or metal from the rock ore. All the unrecoverable and uneconomic remnants from this process are waste. They include finely ground rock particles, chemicals, minerals and water.
Depending on the type of mining, tailings can be liquid, solid or a slurry of fine particles. Tailings dams are used to store water and waste that come as by products from the mining process.
It is estimated there are at least 3, tailings dams around the world. But as there are around 30, industrial mines, the number of tailings dams is likely to be much higher. Tailings dams can be huge in size, as big as lakes, and reach metres high. As the slurry of waste is piped into the dam, the solids settle to the bottom and the water is recycled to be used in the separation process again.
Rather than reinforced concrete, tailings dams use earth or rock to create a barrage. However, most tailings dams use the cheaper but more dangerous upstream method of construction, using the tailings themselves to create a barrier.
The dam is then continually raised to accommodate more waste. These dams are more unstable and more prone to leakage. Tailings dams need regular maintenance and monitoring to ensure that there is sufficient drainage and the dam is strong enough to contain the mining waste. Tailings dams can pose a threat to local wildlife as birds and animals bathe in and drink from the contaminated waters.
Leakage of toxic substances from tailings dams can also cause damage to the immediate environment. In Canada, the Mount Polley copper-gold mine dam collapse in released 25 million cubic metres of wastewater and tailings into adjacent water systems and lakes.
In , the Samarco dam collapse in Brazil released 33 million cubic metres of iron ore tailings slurry into the environment, killing 19 people, displacing families and contaminating waterways for km downriver until it reached the ocean. It is feared that precious ecosystems and fish life that support indigenous communities will never recover.
There are also grave concerns for the safety of legacy tailing dams that are no longer used but still pose a considerable threat to life and the environment if they fail. Traditional storage facilities, such as the ones involved in the Brumadinho and Samarco tragedies, are used by the mining industry simply because they are cheap.
New technologies are available that substantially reduce or mitigate the risk associated with potential dam failures, such as the filtered tailings process, which reduces the amount of water to minimize volume and improve stability. Dry tailings disposal is another alternative that offers significant benefits in terms of environmental sustainability, as well as worker and community safety. What can be done to improve tailings dam safety?
Tailings dam failures are not inevitable and can be prevented. Mining companies must listen to workers and unions, who are frequently the first to flag safety issues but too often ignored. The mining industry must urgently adhere to these standards to prevent future disasters.
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