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Mine waste heaps

Enormous volumes of waste are left over after burning

of oil shale or separation of ore from unwanted solid

matter. It is stocked in gigantic spoil heaps reaching by

places (Kivioli) ahundredmetres high,which sometimes

contain enough natural hydrocarbons for spontaneous

combustion to occur occasionally through natural

oxidation processes. Precipitation, and oxidation

phenomena, also carry sulphates down into the

water table.

Ash

After oil shale has been separated from the unusable

matrix, it is reduced to a powder to fuel electricity

generating stations or thermal power stations, or

used to produce hydrocarbons and solvents for the

chemicalindustry.Thequantityofunusableashproduced

is equivalent to around a third of the weight of the

raw fuel. The Eesti and Balti power stations produce

four million tonnes of ash each year.

Cracking residues

When oil shale is distilled to produce fuels or solvents,

the residues left over from the cracking process are

also deposited on the spoil heaps. They sometimes

ignite spontaneously in contact with the air. Over the

past fifty years, 170million tonnes of cracking residues

have been generated, and these contain large

amounts of organic compounds, phenols in particular.

Rain causes these to leach downwards to the water

table and watercourses. Some drainage ponds at the

foot of the spoil heaps contain reddish-coloured

water, indicating the presence of this pollution.

Spoil heaps of oil shale ash (Estonia).

Terrils de cendres de schistes bitumineux (Estonia).

Source :Enn Käiss

(http://www.galerii.ee/panoraam/eesti/e_sisu.html?id=59)

sustainable water resource management

Spoil heap of ash and mine waste at Kivioli mine (Estonia).

Un terril de cendres et de stériles à Kivioli (Estonia).

Source :Kadriann Sossar

(http://france-estonie.org/

)

Over the past fifty years, 170 million tonnes of

cracking residues have been generated, and these

contain large amounts of organic compounds,

phenols in particular. Rain causes these to leach

downwards to the water table and watercourses."

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