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:: ABB Commissions the Most Powerful Gearless Mill Drives Ever Built
ABB, the leading power and automation technology group, has commissioned automation and power equipment that increases production at Boliden’s Aitik copper concentrator plant, located near the town of Gällivare in northern Sweden.
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 plant has completely replaced the old grinding plant, which will be closed down later this year.
Two gearless mill drives (GMD) power two new 38-foot (11.6 meter) autogenous grinding mills. At 22.5 megawatts each the mill drives are the most powerful in the world. They drive mills with a capacity to grind about 2,200 tons of ore per hour each, expanding production capacity to 36 million tons of ore per year from 18 million tons.
An autogenous mill uses large pieces of ore to grind down smaller pieces by impact in a large rotating drum. The autogenous mill and its GMD is not only one of the largest installations (the ring motor is almost 20 meters high), it is also one of the pivotal applications in a concentrator plant, grinding the ore into small particles with a combination of brute strength and advanced technologies on both the mill and motor side.
The entire site process - including the concentrator plant, 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 optimized 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 the contract included spare parts, network studies, installation supervision and commissioning.
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