Going underground: Middleton Mine
Cost and safety considerations means that almost all limestone extracted in Britain comes from surface quarries. The only limestone worked underground in Britain comes from Middleton Mine near Wirksworth. This mine produces around 120 000 tonnes a year of very high quality limestone which is a vital ingredient used in manufacturing plastics, rubber and glass. Middleton Mine has been driven into the hillside from an exisiting surface quarry and follows a particularly pure limestone horizon known as the Bee Low Limestones. Overlying this pure limestone is a bed of impervious volcanic lava that helps to keep the mine dry by acting as a natural barrier to the passage of water.
|
Mining is carefully controlled, with large pillars of limestone measuring 17 by 17 metres left in place to support the roof of the mine, which may be up to 15 metres high. Undergound mining of limestone has clear environmental advantages, in that most of the operation is out of site and there is a reduction in impacts such as noise and dust. The main barrier to the wider use of underground mining of limestone is its high cost. Health and safety, and mining regulations are expensive to implement underground, and the need to leave limestone pillars to support the roof means that a significant proportion of the valuable mineral goes unused. The high quality of the limestone worked at Middleton Mine means that its market price offsets the higher costs of going underground.
|
