Name: Kristineberg mine.

Location: Skellefteå Municipality, Västerbotten County, Sweden.

Mine Owner/s: Boliden Mineral.

Brief Description: The Kristineberg mine has been in production for the past 80 years and has a production capacity of about 750 000 t/y.

Brief History: The mine has been in operation since 1940, comprising four smaller openpits before the development of underground infrastructure.

Until 1991, there was a mill and concentrator on site. The tailings from the concentrator were deposited in five tailings facilities in the valley below the mine. All the tailings facilities, with the exception of Magazine 4, have been closed and reclaimed or are being reclaimed.

Magazine 4 functions as a settling pond after water treatment with slaked lime. A small quantity of waste rock is temporarily stored in the footprint of Magazine 2; this rock will be used as fill under the life-of-mine.

Primary Metals/Minerals: Copper and zinc.

Secondary Metals/Minerals: Gold, silver and lead.

Geology/Mineralisation: The Kristineberg mine’s camp and surrounding mineralisation of the Rävliden, Rävliden North, Rävlidmyran, Hornsträsksviken and Kimheden areas are considered examples of volcanogenic-hosted massive sulphide mineralisation.

The mineralisation of the Kristineberg Camp are situated on separate stratigraphic horizons, which relate to differing ages and mineralisation events. The Kristineberg mine mineralisation and the Kimheden mineralisation are located on the Kristineberg Horizon, and the Rävliden North deposit is  located on the Rävliden Horizon, along with the Rävliden and Rävlidmyran mineralisations.

The Rävliden North mineralisation and Kristineberg mine mineralisation are located within local antiformal structures. Rävliden North comprises two major first-order antiforms and an intervening synform, or major shear zones, according to Boliden Mineral.

The Kristineberg mine mineralisation is located within multiple layers of stacked lenses of intensely chlorite-altered schists, which have been accumulated by thrusting and associated crustal shortening in a north-north-east to south-south-west direction.

Reserves: Total proven and probable reserves as at December 31, 2020, were estimated at 2.45-million tonnes grading 0.6 g/t gold, 36 g/t silver, 0.6% copper, 5.4%zinc and 0.3% lead.

Resources: Total measured and indicated resources as at December 31, 2020, were estimated at 6.64-million tonnes grading 0.4 g/t gold, 65 g/t silver, 0.8% copper, 4.6% zinc and 0.5% lead. Inferred resources were estimated at 7.77-million tonnes grading 0.3 g/t gold, 60 g/t silver, 0.8% copper, 3.4% zinc and 0.5% lead.

Mining Method: Cut-and-fill, and drift-and-fill.

Major Infrastructure and Equipment: Trucks transport the mined mineralised material to the underground crusher through underground transport drifts.

The material is transported to the surface by the skip hoist, which has a capacity of 160 t/h. Material is stockpiled at the surface materials handling station, where it is then trucked 95 km to the BAO process plant. The route from Boliden to Kristineberg is by an all-weather road.

Underground and surface materials handling are outsourced to contractors.

Tailings facilities exist at the mine site and at the process plant, but are currently decommissioned.

Cut-and-fill operations are conducted at facilities and infrastructure for filling mined rooms. Such infrastructure includes a fill mixing station and all other ancillary vehicles necessary for the filling of completed mining rooms.

Other site infrastructure includes offices and meeting rooms, as well as a core logging and sampling facility.

Prospects: Boliden has decided to invest SKr1.25-billion in expanding the Kristineberg mine towards the Rävliden mineralisation. Most of the investment is conditional on a permit being received for an increase in production. The expansion is expected to contribute to an increase in milled volumes in the Boliden Area to 1.8-million tonnes.

Contact Details:
Boliden Garpenberg
Tel +46 225 360 00
Website https://www.boliden.com/ 

Sources:

Boliden Mineral. https://www.boliden.com/ (accessed: July 17, 2021).