ABB, the leading power and automation technology group, has commissioned automation and power equipment that is helping increase production at Boliden’s Aitik copper concentrator, located near the town of Gällivare in northern Sweden. The whole complex is undergoing an expansion to mine 36 Mt/y (IM, Match 2008). The low grade of the ore requires this Boliden mine to be extremely efficient, as will be examined in IM’s December issue.
Aitik is Sweden’s largest mine and has now become a global industry benchmark in mine efficiency since its completion in August 2010. The new copper concentrator (including the world’s largest AG mills) has completely replaced the old one, which will be closed down later this year. TankCell flotation is another important technology in the plant. Two ABB gearless mill drives (GMD) power two new 11.6 m diameter AG mills. At 22.5 MW each the mill drives are the most powerful in the world. They drive mills with a capacity to grind about 2,200 t/h of ore each, helping expanding production capacity to 36 Mt of ore from 18 Mt/y.
The AG mill and its GMD is not only one of the largest installations (the ring motor is almost 20 m high), it is also one of the pivotal applications in the concentrator. The entire site process – including the concentrator, conveyor systems and pumping stations – is controlled by ABB’s award-winning Extended Automation System 800xA. Around 650 ABB high-efficiency motors and variable speed drives power the pebble and regrinding mills, conveyors, crushers, pumps, fans, and process equipment to ensure minimal energy use and maximum process efficiency. Included is the first high speed dual-pinion drive system in this power range with an optimised control system to avoid load unbalance and backlash.
An ABB gas insulated substation feeds electricity from the power grid to Aitik with minimal electrical losses and minimal space requirements, and ABB low voltage systems distribute the power across the entire site reliably and energy efficiently. The harmonic distortions in the grid are kept below the limits given by IEC/local standards and the installed filter and power factor correction system ensure the power factor is equal to or higher than 0.99.
The scope of ABB’s contract included spare parts, network studies, installation supervision and commissioning.