Some 50 km north of the Arctic Circle in the Lapland region of Sweden is a giant hole in the ground. It's 3 km long, 1.5 km wide, and 250 m deep. This is the Aitik copper mine. About 15 km from the town of Gällivare, it is one of the largest open pit mines in Europe.
Owned by the Boliden Group, which operates mines and smelters in Sweden, Finland, Norway and Ireland, the mine recently completed a massive expansion and modernization project. The price tag for Aitik's upgrade was $790 million, but it's enabled the mine to double its production capacity, extend its life until 2030 and add molybdenum to its list of metals produced.
Aitik's ore is not especially high-grade. It's 0.25% copper, 0.1 g gold per ton and 2 g of silver per ton, but still worth the investment in digging it up. It's not just the market value of the minerals that makes the investment worthwhile. The upgrades Boliden has installed are expected to reduce life-of-mine cash costs from $0.80 per pound to $0.43 per pound, and have raised production rates from 4.3 tons per man hour to 5.5 tons per man hour. Efficient, trouble-free operation is crucial to Aitik's long-term success.
Crush, Shake, Stir
Once a week at Aitik, a blast produces enough ore for the operation to process 106,000 tons each day. The unprocessed ore is loaded onto 100-ton trucks, which deliver it to a crusher deep in the pit. The crusher reduces the ore to 30-cm boulders, which are then transported by underground conveyors to a storage area above ground. From there, a 7-km conveyor moves the rock at 4 m/s to the concentrator plant, where two 22.5-MW gearless mills grind it down to sand at the rate of 4400 tons per hour.
Then the sand goes into flotation tanks filled with reagents, foaming agents, compressed air and chalk, where 500,000 liters of water are added each hour. This treatment separates out the valuable copper, gold and silver ore, which floats to the top. The resulting chalcopyrite concentrate, which is 25% copper, is then transported by train to Boliden's smelter in Rönnskär, 400 km away.
An operation this size has a lot of equipment to be maintained. In addition to the new concentrator, surface crusher and the 7-km conveyer between them, the site has pipelines to its water reclamation stations, pumping stations, a welding shop, a truck garage, administration buildings and a recycling station.
Among the goals Boliden had for the system was to increase the number of reported faults in the system. At first glance, this seems counter-intuitive; one would think the goal would be to reduce faults. But in fact, unreported faults don't get addressed. In the past, using the old solution, operators tended to avoid the complicated, time-consuming reporting process and simply didn't report all the faults they observed.
Now, because System 800xA provides a common visual interface for a diverse assortment of systems, applications and equipment, operators simply click on the object shown on their HMI that they want to report, choose "create fault report," input the problem and submit the report, which then becomes available in Maximo, where the maintenance staff can see complete and correct information, and take action immediately.
The integration of Maximo and System 800xA ensures early fault detection, which has increased the number of faults reported five-fold, according to Aitik. It gives operators the ability to inform the maintenance department about problems while they're still small, and before they can cause a breakdown or an unplanned shutdown.
The mine and its equipment runs 24/7 every day of the year in extreme conditions. As is typical in open-pit operations, it's very dusty. It's also very cold and dark much of the year, and outdoor equipment has to withstand temperatures as low as -45 °C (-49 °F) in winter. The reliability of motors, drives and other equipment is paramount in such conditions—another reason early fault detection is critical.
At Aitik, maintenance is supported not only with the EAM system, but also with the document management system, which is integrated with System 800xA. This gives operators access to drawings, instructions, manuals and other documentation to enable quick and correct actions. In March 2011, Aitik also began using the asset monitor function in System 800xA to support its predictive maintenance activities.
The asset monitors focus on critical parts of the operation that are essential for reliable and profitable operation of the mine. One of these is the gearbox of the large mills. Asset monitors signal the need for maintenance on them, detect anomalies, and take corrective action before a critical situation arises.
Aitik uses one of the extensions available for System 800xA, Snapshot Reports, to keep track of maintenance issues. Preconfigured reports are executed on a regular basis to collect process and maintenance data. "The 800xA standard functions and other system extensions like Asset Monitoring can provide general and specific report functionality. The flexibility of Snapshot Reports gives us the ability to create system reports based on practically any personnel group request," says P-O Lundqvist, senior project manager at Boliden.
Boliden plans to implement the Asset Optimization solution at all of its mines when their 800xA systems are upgraded.