Perhaps the best way to understand Dalradian’s project is to compare it to a hi-tech, highly regulated, precision led quarry – only one that is based underground with some processing on the surface.
There are six stages to Dalradian’s approach. The third is ‘rock management’.
A best in class approach
Operations at Curraghinalt will mine two-types of rock – ‘ore’ which contains metals and ‘non-ore bearing rock’ which doesn’t.
The project is designed to retain as much non-ore bearing rock underground as possible. The remainder will be stored above ground in a Dry Stack Facility (DSF).
Rock is first processed underground through a crusher and an ore sorter. Ore is transported by an electric, covered conveyor to the surface for further processing. Non-ore bearing rock will be used to help backfill tunnels and leave mine workings in a stable condition. Some of this material will also help form the DSF’s outer shell.
On the surface ore is further processed, creating a concentrate containing valuable metals to be shipped overseas. The left-over rock is known as ‘tailings. Just over half of these tailings will be pumped underground and mixed with cement to
backfill cavities. The remaining tailings will have most of their water removed before being sent to the DSF.
Traditionally, tailings would have been stored as a semi-liquid in ‘wet tailings dams’. By using the latest DSF technology (acknowledged by the EU as a best available technique) there will be no ‘wet tailings dams’ at Curraghinalt. Scotland’s new gold mine in the Trossachs National Park (similar climate and topography to the Sperrins) also uses DSF technology.
The DSF is an engineered, designed feature which is smoothed, shaped and compacted safely and securely. Over the c.25-year life of mine, it will have an average thickness of c.17m and won’t contain acid-generating rock.
Located in a natural hollow, the DSF will be contoured and progressively planted during operations to help it further blend in with the surrounding area, much like a landscaped embankment. Dalradian’s Environmental Statement contains detailed plans for the DSF which are being reviewed by planners and their expert consultants.
Water draining from the DSF (typically rainwater) or any water which comes into contact with mine operations will be captured and treated in a state of-the-art, reverse osmosis water treatment plant in line with strict regulatory standards.