Lime products are used to control pH fluctuations in the runoff. There have been mining operations in many places in Norway over the years. Mining has disrupted the natural state of minerals, making them unstable. This has resulted in leakages of minerals and heavy metals, which have now become a threat to the local ecosystem. In places where sulphur, iron, nickel and copper have been mined, Norwegian watercourses are at risk of being polluted by environmentally harmful substances from the old industry.
For many mining areas, this means that if nothing is done to sanitise the bedrock or the water in the mine is not treated, there will be contaminated runoff for many years to come.
While the pyrite minerals contribute to acidification and increased levels of iron and copper (copper is a heavy metal), the oxidation of iron contributes to siltation of watercourses. In addition, large amounts of heavy metals enter watercourses in the form of copper, nickel, cadmium, zinc and lead, which can pose a threat to ecosystems. Wild salmon is particularly threatened by high copper values.
Depending on the composition of the mining water, the runoff from the mines can be treated by adjusting the pH using lime to control pH fluctuations in the runoff water. Furthermore, heavy metal will precipitate at different pH ranges.