Gypsum Mining in Cumbria
Gypsum (hydrated calcium sulphate) has been quarried or mined at Kirkby Thore for over 200 years. The gypsum is ground to a powder and heated to evaporate water. Heating to approximately 160ºC drives off a limited amount of water and Plaster of Paris is produced. The most important use of this type of gypsum is in the production of plaster and plasterboard. Heating to above 200ºC drives off all the water to produce the anhydrite which is used in the production of Portland Cement. More recently synthetic gypsum (desulphogypsum) has been derived as a by-product of the desulphurisation of flue gases at coal-fired power stations (Drax, Ratcliffe-on-Soar, and West Burton).
The British Gypsum plant at Kirkby Thore is a major source of plaster building materials and also hosts a training centre for their uses. Large amounts of desulphogypsum are transported via the Settle to Carlisle railway to Kirkby Thore for processing. This traffic is a significant factor in keeping the line open.
In Cumbria, several gypsum/anhydrite beds occur in mudstones of late permian age in the Vale of Eden. Gypsum and anhydrite mining is now confined to the Kirkby Thore area, where two beds ‘A’ bed and ‘B’ bed are worked for plaster, plasterboard and cement manufacture. The ‘A’ bed is worked at the Birkshead Mine [Long Marton NY665256], and anhydrite forming the ‘B’ bed is extracted at the Newbiggin Mine.
In the Eden Valley gypsum was also mined at Cocklakes and Cotehill, near Carlisle, and from under Long Meg and her Daughters, near Little Salkeld. Remains of the Long Meg mine (operational till 1976), railway sidings and Long Meg signal box can be seen along the footpath from Little Salkeld to Lacy’s Caves.
- British Gypsum
- Wikipedia – Gypsum
- Wikipedia – Desulphurisation
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