With its world-class expertise in rotating electrical and mechanical machines, Marthinusen & Coutts (M&C) recently changed out a large ball mill motor at a gold mine in Kyrgyzstan.

The planning and work to replace the 36t synchronous motor with a brushless exciter was conducted in just 16 days over the December 2019 shutdown. According to Andries de Lange, Field Service Technician at M&C, this was done to reduce any impact on production.

“The ball mill is at the heart of the mine’s plant, and the customer chose to use M&C as they could rely on our quality workmanship and our ability to meet agreed deadlines,” said Andries. deadlines,”  “The contract followed extensive engagement with the mine on various project options and included our taking responsibility for sub-contracting certain aspects of the work.”

M&C was required to conduct the motor replacement as well as ancillary work related to the mill and infrastructure, including a new base frame. This meant that among the project team that headed to Kyrgyzstan in December 2019 were eight specialised subcontractors from South Africa.

“After a period of pre-shutdown preparation, we were able to move the 40t overhead crane into position, removing covers and other components in readiness for moving the motor,” Andries said. “After the motor was lifted out, the existing base frame could be removed and a new one installed in line with stringent OEM procedures and specifications.”

The new motor was retrieved from storage and thoroughly inspected before installation on a new base frame. Following this, the full range of checks and adjustments were made. Electrical fitment and alignment then followed, with the inspection and testing of the stator, rotor, exciter rotor, exciter stator and all components.

“Our running checks included testing for vibrations on the drive-end and non-drive-end bearings, and bearing temperature measurements,” he said. “With our combined experience in both motors and mills, we were able to leave the customer well-assured that the new equipment would run productively and reliably.”