Maurliden
We are working continuously to develop new reclamation alternatives, and many of the measures implemented in older decommissioned mining areas hence involve complementing yesterday's reclamation techniques with today's. Reclamation is also carried out continuously throughout the operating lifespan of the mine. Maurliden Östra, which was opened as recently as August 2010, is one example of this. Successive reclamation of the waste rock dump will be carried out there every year with the help of composite till cover. A similar process of reclamation is also being carried out on the waste rock dump at Aitik.
Gillervattnet
A total of 38 million tonnes of tailings sand from the Boliden Area concentrator has been stored in the Gillervattnet tailings pond over the years. The tailings pond, which has been in operation since 1958, was replaced in the autumn by the Hötjärn tailings pond. The reclamationwork will commence in 2012 and a number of different techniques will be used to minimise the oxygen transport to the tailings sand. The Hötjärn tailings pond can provide a total of 1,300,000 m³ of composite till for the cover work. This approach offers several advantages, including eliminating the need to remove the composite till from undisturbed land and increasing the deposit capacity of the Hötjärn tailings pond. Stabilisation materials will be taken from a variety of sites, including the waste rock pile at Kankberg.
This is how it works
The biggest surface area in Gillervattnet − approximately 190 hectares − will be covered with water, and the dam level has been set at 221.5 m above sea level. 47 hectares will be covered with water to a depth of max. 1 metre.
Areas with a water depth of between 1.0 and 1.5 m will undergo bottom stabilisation, using composite till cover to ensure that waves do not disturb the tailings sand. Areas with a water depth of between 0.5 and 0 m will be covered with composite till to ensure that an elevated groundwater level is achieved.
Tailings sand above the surface of the water will be covered using a packed layer of dense composite till and then a protective layer of composite till.