MechChem Africa February 2018

⎪ Plant maintenance, lubrication and filtration ⎪

Gearless mill drives assembled for Cobre Panamá project

M arthinusen & Coutts (M&C), a division of ACTOM, recently executed the sub-assembly of six gearless mill drives for inera Panamá’s remotely situated Cobre Panamá project in record time, and as a result could hand the machine over to the mechanical teams for professional assembly well ahead of schedule. Minera Panamá, the Panamanian subsid- iary of First Quantum Minerals, is currently developingtheCobrePanamáproject,located inColónprovince. Themine life has been esti- mated atmore than30years andwill produce around300000 t/y copper, 100000oz/y gold and 2 500 t/y molybdenum. M&Chas a proven track recordpartnering with customers on similar complex projects, while still being able to offer a cost-competi- tive solution. This leading repairer of rotating machineryhas anestablished reputationas an expert in gearless mill drive refurbishment, winding termination and testing of motor segments. Of the six ABB gearless mill drives being installed at Cobre Panamá, four will power ball mills and the other two will drive SAG mills. Thesemassivemachines are among the largest ever installed in the world and were transported in quartered sections to site for assembly in situ. The sheer size of themachines, with an in- sidediameterof14m,presentedchallengesof its own, with each segmentweighing approxi- mately 80 t. Work was done in four different positions on the machines simultaneously, at 3 o’clock, 6 o’clock, 9 o’clock and 12 o’clock. Commenting on the role thatM&Cplayed in thisproject, divisional CEO, RichardBotton, says that a team of six highly competent and skilled technicians was responsible for the completion of the project within extremely tight time schedules. Work on the machines was performed back-to-back and this was accomplished using induction-brazing equip- Marthinusen & Coutts, part of ACTOM, is a leading repairer of rotating machinery with a proven record in gearless mill drive refurbishment. Through the level of skills and expertise that reside within this service provider, the company has established a strong reference base and reputation.

The Marthinusen & Coutts team that successfully executed the sub-assembly of the six gearless mill drives (back from left): Wesley Ludeman, assistant winder; Chico Bernades, field service technician; Shepard Chigmwa, senior winder and Keith van den Heever, assistant winder. (Front from left): Rico Coertze, assistant winder and Wynand Willemse, senior field service technician.

ment, andabar-woundwindingwith separate upper and lower stator bars, as opposed to set diamond lap-wound, formed-type coils. Another major challenge that the team had to contendwithwas the adverseweather conditionsatthelocation.Thisregionreceives 5-7 m of rain per year, with ambient tem- peratures often exceeding 35 °C with daily humidity levels above 80%. Botton says that working closely with the OEM ABB on this project was vital to its success. He pointed out that it is not unusual for M&C to partner with OEMs on projects such as this. Massive mill motor refurbished The largest AC electric motor operating in Zimbabwe drives a reduction mill, and this synchronousmotorwas recently refurbished by M&C. Estimated to be around 30 years old, the 2150 kWsynchronousmill motor, whichwas in operation at Freda Rebecca Gold Mine, suffered a catastrophic failure caused by its age and metal fatigue. The main hub of the electrical rotor component had sheared off. Following preliminary repair work under- taken by the mine, M&C was called to site by

themine to investigate further and toprovide a long-termworld-class solution. Afull assess- ment undertakenby theM&C’s teamresulted in themotor being takenback to thedivision’s facility in South Africa. Itwas decided, followingnegotiationswith the mine, to do a design modification instead of replacing the hub. Botton explains that this option was chosen as it would save costs and reduce the lead-time without sacrificing the performance of the refurbished motor. “Our team’s extensive experience and understanding of large rotating machinery enabled us to offer an alternative to themine that would ensure optimum reliability in the future. One of the solutions was to use the existing rotor superstructure with a bolt-on hub on the motor,” Botton says. Acompleterewindofthestatorwasneces- sary due to the extensive damage causeddur- ing the failure at themine. Acompeteupgrade and modification to the sleeve bearings also brought these back to OEM specifications. The scope of work included the on-site commissioning of themotor, whichwas facili- tated by the M&C Zimbabwe operation with technical support from the division’s centre of excellence in Johannesburg. q

February 2018 • MechChem Africa ¦ 11