EXPLORATION ’93 — Boliden works copper mine in Sweden’s

Some 27 million tonnes of material are moved annually at the open-pit Aitik copper mine of Boliden in northern Sweden, Mannesmann Demag reports.

The equipment manufacturer has two large hydraulic shovels working at the mine, which lies north of the polar circle, at the small town of Gallivare, 900 km north of Stockholm.

Copper deposits were uncovered in northern Sweden as far back as the 1930s but the low grade (0.35% copper) of the material left it untapped for many years.

Development at Aitik began in 1965, with production initiated in 1968. Almost 13 million tonnes of overburden and 13.5 million tonnes of mineralized material are moved each year.

Large-hole drill carriages are used to drill through the extremely hard and abrasive rock before blasting. Demag’s super shovels then dig out the pre-blasted rock directly from the face and load it on to dump trucks. The material is transported 600-800 metres to an in-pit crusher, from where it is moved via underground steep-gradient belt conveyors to the concentrator at the edge of the mine.

A 4-stage flotation plant produces about 190,000 tonnes of concentrate each year, which yields about 54,000 tonnes of pure copper. Some 44 tonnes of silver and 1.9 tonnes of gold are produced each year as byproducts. The mine is 2.5 km long, 700 metres wide and 250 metres deep. It is projected that reserves will keep the mine operational well after the turn of the next century, at which time the mine will be 400 metres deep.

Temperatures at the mine site vary between minus 40C and plus 30C during the year. Changes in excess of 20C can occur within a few hours. Boliden is part of the Trelleborg group of companies and operates 14 mines, four concentrators and a copper smelter in Sweden. In Canada, Trelleborg is a 50% owner of Falconbridge, a producer of nickel and other base and precious metals.