SOUTH AFRICAN TECHNOLOGY AND SERVICES
The Balama plant, which was the largest footprint project yet tackled by Zest Energy, will initially run with seven 2,200 kW generators; six running and one on standby, and will later be expanded to include 11 generators, of which two will be standby units
Resources as a low cost, high grade open pit mining operation. Its first gold production is targeted for 2017. Zest WEG Group is supplying an energy efficient solution to drive the mill.
Following close collaboration with the mill OEM, Zest WEG Group provided an optimum solution which will meet the performance parameters of the milling circuit while ensuring cost efficient operation.
David Claassen, Executive at Zest WEG Group, says that this is a good example of where the group is able to leverage not only its extensive expertise in electrical solutions for mill circuits, but its access to a comprehensive range of quality products.
Zest WEG Group is the South African subsidiary of leading Brazilian motor and controls manufacturer WEG. The group’ s product line-up includes low and high voltage electric motors, vibrator motors, variable speeds drives, soft starters, power and distribution transformers, MCCs, containerised substations, mini-substations, diesel generator sets, switchgear and co-generation and energy solutions as well as electrical and instrumentation construction and project execution services. Claassen says that the company is able to exercise absolute control over the packaged solution including shortening lead times and offering customers the flexibility in meeting exact application requirements.
The electrical solution for Yanfolila includes a 2,000 kW, 6 pole, 6,6 kV squirrel cage WEG electric motor, a medium voltage WEG Variable Speed Drive and a dry type phase shift transformer. The VSD and transformer will be housed in a custom engineered and manufactured sub-station. The sub-station will be manufactured and fully tested at Zest WEG Group’ s sub-station and panel facility in Johannesburg.
“ Another very important advantage to the customer is that in dealing with a single OEM, the fully completed electrical solution will be shipped to site as a plug-and-play solution,” Claassen says.
The electrical solution is scheduled for delivery to site in the first quarter of 2017 and Zest WEG Group will be responsible for all interfacing between the VSD and upstream MV switchgear, output isolation and complete control and protection system including frozen charge protection.
Another Zest application is at the remote operation to mine one of the world’ s largest finds of high grade graphite – the Balama deposit in Mozambique – which will be powered by a generator plant being constructed through Zest Energy, part of the Zest WEG Group.
According to Alastair Gerrard, Managing Director of Zest Energy, the plant will begin producing electricity during the first quarter of 2017, with an initial capacity of 12.5 MW from an installation of seven 2,200 kW diesel generators.
“ The isolated location of the Balama mine – over 250 km west of Pemba in northern Mozambique – means that while the operation does have access to power from the national grid this will need to be supplemented to ensure an adequate supply for full plant demand,” Gerrard says.“ We are therefore required by the customer to ensure 100 % availability, and have consequently designed the plant with substantial standby capacity to allow for maintenance and repairs without affecting the continuous supply.”
“ One of the challenges of the mine environment is the presence of graphite dust, which is highly conductive and must not be allowed to enter the power generation units,” Gerrard says.“ For this reason, a filter system was designed that could accommodate the high volumes of moving air required to cool the engines, while also requiring as little maintenance as possible.”
A local solution was designed, in the form of a custom-engineered, self-cleaning cartridge type ventilation and pressurisation fan unit, comprising four WEG 7.5 kW fan motors. IM
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52 International Mining | JANUARY 2017