Protests OVER the expansion of a Sterlite
Copper smelting plant in Tuticorin, Tamil Nadu, which led to
police firing that killed 13 people, have been over pollution concerns. How do
copper and smelting of the metal pollute?
Dr Purnendu Bose of the
environmental engineering faculty in IIT Kanpur explains that copper, while an
essential nutrient, is toxic to animals and humans in high concentrations.
The main pollutants are
released by the process of smelting. Most copper ores are
sulphur-based and smelting releases sulphur dioxide, an air
pollutant known to have many harmful effects. Sometimes, depending on the
quality of the ore, the concentration of sulphur dioxide is so high that
industries are forced to convert it into sulphuric acid, which itself is
a water contaminant.
The other byproduct of smelting is
slag, the waste matter separated from metals. This slag may leach
heavy metals (arsenic, cadmium, lead or mercury depending on the
composition of the ore) into groundwater reservoirs. Water which has a high
heavy metal content is very toxic to humans.
Slag may also increase the
concentration of other, less harmful salts in water resources, which may
change the taste of water.
The proper disposal of these
byproducts can restrict the pollution caused by these factors to within the
limits permitted by the government and other regulatory bodies.
Credit: Indian Express Explained
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