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
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
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.
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."