Extreme PLCs to boost Lapland goldmine uptime 12 February 2014

Eight large PLCs rated for extreme conditions are being commissioned at Agnico Eagle's gold mine – the largest in Europe – in Lapland, as ABB upgrades automation systems that have been causing problems.

The PLCs will control the sedimentation process of the concentrating mill in northern Finland, 150 km inside the Arctic Circle, near the town of Kittila.

Standard industrial grade PLCs, supplied by other unnamed vendors and housed in freeze-protected cabinets outdoors, had been suffering stoppages – some due to power outages, but others caused by condensation on the PLC modules, which happens in seconds if the cabinet doors are opened at temperatures down to -40 C.

That led to process stoppages resulting in serious consequences, including frozen and blocked pipelines.

Hence, ABB – which had won the original contract for the main automation system at the gold mine, and installed electrical automation based on its 800xA Extended Automation system – was asked to propose a solution based on its XC 'extreme conditions' PLC, a variant of the AC500.

Risto Haavisto, of ABB Finland, explains that this PLC has built-in protection against threats including high and low temperatures, high humidity, low air pressure, salt mist, hazardous gases, and vibration and shock.

In this case, the ABB XC PLCs will be installed at the mine's above-ground processing centre, with I/O modules located at a remote water pumping location and connected using ProfiNET.

"Ruggedised PLC technology opens up new design possibilities, allowing automation to be sited right where the control I/O is needed – in many cases without high-specification environmental protection," comments Haavisto.

Agnico Eagle's gold mine has an estimated lifetime to 2037: Kittila's reserves are estimated at almost 33 million tonnes.

Ore was originally mined from two open pits, starting in 2008. Since 2010, mining has moved underground. Some 3,000 tonnes of ore is currently transported daily to the surface crusher, using underground haul trucks via a 3km ramp access system.

Brian Tinham

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