Motor reliability critical for mine

Cameco Corp. of Saskatoon, SK, is one of the world’s largest uranium producers. Otherwise known as the Canadian Mining and Energy Corporation, Cameco was formed in 1988 by the merger and privatization of two crown corporations.

Cameco’s operations account for about 16% of the world’s uranium production from its mines in Canada and the United States. The corporation produces 11.34 million kg (25 million lb) of uranium a year, with 8.2 million kg (18 million lb) coming from its Canadian facility. Most of the mining takes place in Canada, but there are also facilities in Smith Ranch, WY, Crow Butte, NE, and in the Republic of Kazakhstan.

Mining at the main Cameco facility at McArthur River, located 620 km north of Saskatoon, takes place underground near the Athabasca Basin, which hosts the largest high-grade uranium mines and deposits. Because water is roughly 20 m (65 ft) from the mining location, it is critical that the surrounding water be frozen. If the water is not frozen, then it will flood the mining zone, putting the workers and uranium at risk. To control the temperature of the water, Cameco uses freeze compressors that are controlled by electric motors.

The electric motors are a critical element in keeping the operation running smoothly. Currently, Cameco is running 650 hp, 5,000-volt motors.

Nearly two years ago, Cameco started experiencing maintenance issues with the motors that were powering its compressors. The end bearings were wearing out and the compressors stopped working. While backup motors were available, Cameco began to look for other motor options that would be more reliable and last for a longer period of time.

After consulting with Precision Electro-Mechanical Ltd. (a WEG distributor in Saskatoon and a member of EASA, the Electrical Apparatus Service Association), Cameco made the decision to replace the failing motors and all future motors with WEG electric motors. “WEG’s electric motors greatly surpass the level of quality of other motors on the market,” says Dwight Radloff, the electrical foreman at Cameco.

The compressor-duty motors are designed to meet the high torque requirements of air compressor loads. Special electrical and mechanical features ensure reliable service and long motor life.

Standard features of WEG compressor-duty motors include: single-phase, two-pole, 60 Hz configuration; manual overload protection; start capacitor; squirrel cage rotor; Open Drip Proof (ODP) design; fan cooled (internally); ball bearings; NEMA dimensions; and high starting torque.

In addition to the compressor-duty motors, Cameco is also using several other WEG motors, including 700-hp, 460-volt HGF motors for pumping. WEG’s electric low-voltage H line features simple and compact construction and is manufactured in finned, cast iron frames for severe-duty applications. Internal and external fans are also provided, resulting in an inside temperature balance that helps to extend the winding lifetime of the motor and improves performance.

The compressor-duty WEG electric motor has been operating for over 18 months without any mechanical issues. In the future, Cameco plans to replace any failed motors made by other manufacturers with WEG products. “We expect these motors to last twice as long as those that we were previously used to power our compressors,” says Radloff.

Cameco’s McArthur River deposit, which has ore grades about 100 times the world average, was discovered in 1988 and production began in 1999. The mine has reserves sufficient to sustain production until 2033. MRO

This report was updated and edited by Bill Roebuck based on information provided by WEG, Cameco and other sources.

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